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XyZspineZyX
08-31-2003, 02:38 PM
I heard the p47 was heavy, I read about it. But, in FB it's practially immobile. I think the bombers fly better!

Was it really like this in real life???

S!
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XyZspineZyX
08-31-2003, 02:38 PM
I heard the p47 was heavy, I read about it. But, in FB it's practially immobile. I think the bombers fly better!

Was it really like this in real life???

S!
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XyZspineZyX
08-31-2003, 03:14 PM
Actually, with the huge exception of the rollrate, FB's Jug is the best I've seen in a realistic Flightsim yet. What exactly do you mean by "immobile"? We know the rollrate is porked, but you don't expect it to do sustained turnfights against, say, 109s, do you? In the recent Flight Journal Special Issue "P-47 Thunderbolt" you can read some accounts, including one of Zemke. He says he always engaged his targets from an altitude advantage, tried to sneak in on their low six for a surprise kill and zoom back up, almost never cutting back on the throttle. He did not bother to throttle back in order to stay behind the bandit and tangle with him, he said. During escorts, he loved to fly in the most forward flight, which was more or less a fighter sweep, bouncing the bandits which just scrambled to intercept. All that sounds pretty much what I do with the Jug in Online Flightsims http://ubbxforums.ubi.com/infopop/emoticons/icon_wink.gif. It is notable that Jug accounts usually sound very different to Mustang accounts though. However, you can also read that they followed other fighters down to the deck which were trying to escape, doing rolling evasives, but that seemed to be no appropriate tactic against the Jug, unlike here http://ubbxforums.ubi.com/infopop/emoticons/icon_wink.gif. The Jug reacted quickly and light on the controll inputs. And of course again you get the impression that the "hellish" firepower of 8x 50cal heavy machine guns was much higher than here, against 190s or not.

When you read one about the Mustang, you often hear something about turnfights and lots of maneuvering in the horizontal as well as in the vertical. That very much fits to what you can do with the Stang in other sims, like Warbirds e.g. - When you are good, you can tangle with 109s (especially G6/R6) on co-E - but mostly because most 109 pilots suffer from a similar phenomenon like Spit pilots against 109s: Because their craft has superior turn, they TURN HARD. With wise maneuvering, you end up with an E advantage over them and debunk 'em. But still, the Mustang is best used as a B&Zer. It's very similar to the FW-190, with less rollrate and better flat-turn.

=38=OIAE

47|FC=-

XyZspineZyX
08-31-2003, 03:18 PM
Wait, forgot to say: IBTL /i/smilies/16x16_smiley-wink.gif

=38=OIAE

47|FC=-

XyZspineZyX
08-31-2003, 08:39 PM
Yeah, unfortunately many people thinkng that fights of all fighters looks same. They are wrong. Different planes have different tactics of fighting. Once are better in vertical, other not. Some are better at low, other at high alt etc. You must know what is character your favorite plane and use it in fight. Then, for sure, you will shut down even 190D, flight on p47. http://ubbxforums.ubi.com/infopop/emoticons/icon_smile.gif

XyZspineZyX
08-31-2003, 09:39 PM
I don't know what you've been flying. Try flying the P-47. It flies GREAT.
Whatever you've been flying that flies like a bomber was no P-47.
Not in FB anyway.
S!
Chris


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XyZspineZyX
08-31-2003, 11:15 PM
the p-47 roll rate will be fixed it has already been anounced

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XyZspineZyX
09-01-2003, 12:39 AM
Ok, I'm being misunderstood.

1. I'm not asking to turn inside a 109. Never mentioned anything about being able to turn hard or keep a sustained turn.

2. I do know the roll rate will be fixed.


Maybe #2 is causing me to think this way. It isn't 'turning' that I am talking about, simple mobility - it's got a heavy feel for sure, but not very responsive imo.

ie. BnZ dive. Very difficult to compensate for any jink by a bandit. (Especially with this silly sound bug where they hear you coming). Robert Johnson talks of the vector roll, etc.. and I get a sense that a p47 could compensate better on adjustments made in this example.


I used the word immobile to avoid any talk of 'sustained turns', etc..

I'm a bnz oriented pilot and yet still find the p47 lacking in general overall mobility. (I use the p47 D10 model - still find the view to be pretty bad -- almost as bad as the 190's) - granted it climbs better in 1.1b, but still is like flying a 747 :P

S!
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XyZspineZyX
09-01-2003, 12:47 AM
The higher the average speed of combat becomes, the less important the elevators become. Rolling action comes of much higher importance since all turn performances of planes are limited by G-loads, inertia and human physique when the speeds are very high.

It is not surprising you have felt that way when trying a conventional "BnZ" attack.


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XyZspineZyX
09-01-2003, 12:54 AM
Makes sense.

Have to try again when roll rate is adjusted.




S!
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XyZspineZyX
09-01-2003, 12:56 AM
The plane doesn't dive that well either. Even low wing loaded, low power aircraft can easily keep up with it in a dive.

The entire high subsonic flight model in this game seems to be limited to a simple extention of the low subsonic flight model, with no accounting for compresability or other such effects. All planes dive alike here, and it really cripples the Jug.

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XyZspineZyX
09-01-2003, 01:15 AM
The "dive escape" not seeming to be effective, IMO, is due to the differences in game and reality, rather than a 'flaw' of a physics model within the game.

I often clearly see and meet the situation that I am distancing away from a lighter plane by means of dive, in FB. But the problem is, in real life, a pilot would not be so encouraged to chase a target going into a dive with such high speeds. We have to take into account that in real life, even a mere high-speed Split-S was often enough to discourage an attacking plane.

But in the game, we don't have to wrestle around with our stick, grunting and pulling, hoping the controls don't lock up. What we do is casually follow the diving P-47 with a dive with almost full throttle, and enjoy the grand slalom downwards without experiencing any of the unpleasant and fear-striking G-loads and dive speeds.

So what usually happens in a game, is a P-47 distances away from a plane during a dive, but the attacker just does not quit his chase. He follows the P-47 to the ground, and when the P-47 may not dive any longer, the faster plane just catches up.

Maybe there really is something lacking in dives with the P-47, but I think what's happening now, would not stop even if it was corrected. It's more of a circumstantial thing, than a FM issue, IMO.



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XyZspineZyX
09-01-2003, 02:31 AM
HarryVoyager wrote:
- The plane doesn't dive that well either. Even low
- wing loaded, low power aircraft can easily keep up
- with it in a dive.
-
- The entire high subsonic flight model in this game
- seems to be limited to a simple extention of the low
- subsonic flight model, with no accounting for
- compresability or other such effects. All planes
- dive alike here, and it really cripples the Jug.


Dive performance is not a function of wing load or power, it's a function of power loading. Nevertheless the power loading advantage was little in steep dives, where all the planes dive almost the same up to max speed in level flight where the heavier planes and those that have higher critical Mach number dive better. P-47 had a bad power to weight at low altitudes and better than most at altitude - for this reason P-47 was outdived at low altitude and outdived most at high altitude. At medium altitudes it was average. After max speed in level flight was reached P47 dived better than anything for two or three more seconds, then the pilot should pull out fast because P-47 was extremely hard to pull out of dives at speeds over 500mph. This is the reason why it was fitted with dive flaps.


What really cripples the Jug is the bad high altitude model, also the fact that most online fights are at low altitudes.

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Message Edited on 08/31/0308:38PM by Huckebein_FW

XyZspineZyX
09-01-2003, 03:42 AM
Kweassa makes a good point. Something I've disliked for some time now. Basically, due to the nature of how this sim was put together it's impossible to recreate historical situations more often than not. Sometimes I think that inaccuracies need to be implemented to account for things that can't be recreated (like G forces, lack of radio, lack of fear of death, etc).

But that gets into another topic altogether. What I've been finding is that the Jug won't climb, won't dive particularly well, won't roll for crap. has little acceleration or high end speed, bleeds off all speed in a climb at a frightening rate (preventing much in the way of basic ACM), but worst of all, has a gun spread worse than bird shot from a shotgun sawed down to 2 inches on a target 100 yards out.

Correcting the roll rate is welcome. I wonder why it wasn't done in the last long awaited patch, but, it's not all that needs to be done. The gun spread is criminal. There is no reason for it to be as bad as it is. It was also known for great zoom climbs IRL. "Great" meaning in comparison to enemy aircraft. I don't see that at all in FB.

Would really be nice if we got one of the late P-47s, something with some speed, like the J or M. But, at this rate it feels like we are likely to get stiffed on the P-51. /i/smilies/16x16_smiley-indifferent.gif

Basically, it does fly worse than bombers.

Oh, btw - just for kicks I was screwing around online with BP_Machine, who was flying an He-111. He was turn fighting, and I could not get a shot on him at all. Couldn't turn with him, couldn't get an advantage in climb or dive either. /i/smilies/16x16_smiley-indifferent.gif

XyZspineZyX
09-01-2003, 07:44 AM
Salute Huckbein

I'm sorry, but after hearing you spout this nonsense about powerloading being the key to diving for so long its time to call your bluff.

Powerloading is only a factor for the first few seconds. After that, gravity and drag become much more important. And the fact that aircraft very quickly reach their limit dive speed. After a dive of a few thousand feet, all aircraft reach their terminal dive speed. (unfortunately in FB, dive acceleration seems very slow and it takes much longer to reach terminal speed)

All the reports from both sides put in detail the advantages the P-47 had over its German opponents in the dive.

There are many US aircraft which have better powerloading than the P-47 and which were also outdived by it.

XyZspineZyX
09-01-2003, 08:03 AM
Wait till they fix rollrate, before that you cant do vector rolls.
Personally I like P47, best boom zoom plane.

Recon_609IAP wrote:
- Ok, I'm being misunderstood.
-
- 1. I'm not asking to turn inside a 109. Never
- mentioned anything about being able to turn hard or
- keep a sustained turn.
-
- 2. I do know the roll rate will be fixed.
-
-
- Maybe #2 is causing me to think this way. It isn't
- 'turning' that I am talking about, simple mobility -
- it's got a heavy feel for sure, but not very
- responsive imo.
-
- ie. BnZ dive. Very difficult to compensate for any
- jink by a bandit. (Especially with this silly sound
- bug where they hear you coming). Robert Johnson
- talks of the vector roll, etc.. and I get a sense
- that a p47 could compensate better on adjustments
- made in this example.
-
-
- I used the word immobile to avoid any talk of
- 'sustained turns', etc..
-
- I'm a bnz oriented pilot and yet still find the p47
- lacking in general overall mobility. (I use the p47
- D10 model - still find the view to be pretty bad --
- almost as bad as the 190's) - granted it climbs
- better in 1.1b, but still is like flying a 747 :P
-
- S!
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XyZspineZyX
09-01-2003, 08:17 AM
Just a few thoughts of mine as I have flown the P-47 in every sim I have owned and love what we have so far. That being said there are some serious error's in it's FM and DM. Before I get into that I want to point out a few things some may not know about the Jug in FB and how to make her fly a little closer to reality.
1) I know everybody here is full aware of trim, but it is truely one of the most important factors of the Jug we have. If you give her about 2 degrees down trim she accelerates fairly well, and "E" bleed is far reduced.
2) Mixture another component we are all well adjusted to and use in almost all a/c we fly. But keeping tabs on where to change it is very important to the Jug's performance. I drop to 80%@2-2.5k, 60%@6k and 40%@8k. You will hear the difference in the engine and feel the difference in her too(if your sound is pooped out/i/smilies/16x16_smiley-wink.gif )
3) The 8 M2's are greatly improved over the initial release of FB and I have no problems with them, I use a convergence of 250m which allows me to use deflection or hose them down with lead as the say.
4) I have personally found before entering a dive I lower my prop pitch to 80% and let her rip, and nothing other than 262's and other Jug's have caught me. And if you want to zoom climb slowly step up your pitch when on the upward part of the climb you will notice your speed bleed's alot slower this way.
Now the Jug isn't the most nimble plane out there and nobody should expect her to be. But she is a very competent and leathal fighter if flown properly. Now if the top-speed and roll rate get fixed you will see a whole new world and all of us full-time Jug Jocks will be smiling from ear to ear that we finally got her the closest to reality any game could get us. My one and only complaint on the Jug other than the roll rate is the unreliablility of the most reliable engine in a prop fighter. I could not tell you how many time's I have caught the "magic bullet" in a cylinder and had to belly land in enemy territory. This is an engine that is well documented of having returned to base hundred's of mile's with entire cylinders blown off of the block. But I rather doubt that this is only affecting the Jug and think it would be pretty hard to code such things, so I will live with it. If ever I get mad about it, I think to myself how much better the Jug is here compared to other games like CFS1 and I shudder at the injustice the Jug and many other planes were given there. That is just my perspective on the Jug as that is pretty much all I fly and the reason I bought this game, all of the other planes were just a bonus to me.
~S!
Eagle
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XyZspineZyX
09-01-2003, 09:14 AM
Salute

Write Oleg and tell him about the damage issue. Magic bullet, plus the question of the turbocharger being knocked out and killing the engine... didn't happen that way.

XyZspineZyX
09-01-2003, 09:41 AM
"I could not tell you how many time's I have caught the "magic bullet" in a cylinder and had to belly land in enemy territory. This is an engine that is well documented of having returned to base hundred's of mile's with entire cylinders blown off of the block. But I rather doubt that this is only affecting the Jug and think it would be pretty hard to code such things, so I will live with it."

That is an agreeable attitude.

Complex modelling of damage is eternally in a dilemma, since the more variety of situations and damage one receives, the more it tends to be inconsistent. While a certain tendency is to be noted, frankly, the damage model issues are one of the parts which the gamers have no way of proving.

As an opponent to P-47s most of the times, in my case, sometimes they seem to soak up bullets eternally, other times a well placed burst somehow just kills the engine instantly - and same with all planes for that matter, as you have said.

What really would help, would be a statistic report of damage through months of play, indicating rounds, area, and extent of damage to a certain model - and see if that concurs with some statistics on damage reports in real life. But I doubt anyone would go so far as to do that.




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XyZspineZyX
09-01-2003, 11:41 AM
BlitzPig_DDT wrote:
- But that gets into another topic altogether. What
- I've been finding is that the Jug won't climb, won't
- dive particularly well, won't roll for crap. has
- little acceleration or high end speed, bleeds off
- all speed in a climb at a frightening rate
- (preventing much in the way of basic ACM), but worst
- of all, has a gun spread worse than bird shot from a
- shotgun sawed down to 2 inches on a target 100 yards
- out.

The relatively indifferent climb and acceleration are
at least fairly accurate. The climb until late on
with additional power and paddle props was pretty
ordinary. It's not going to be like a 109K4 in terms
of sustained climb.

- The gun spread
- is criminal. There is no reason for it to be as bad
- as it is.

Do we know if it is accurate or not? It might be
accurate?

- Oh, btw - just for kicks I was screwing around
- online with BP_Machine, who was flying an He-111. He
- was turn fighting, and I could not get a shot on him
- at all. Couldn't turn with him, couldn't get an
- advantage in climb or dive either.

The He-111 was nimble for its size, and is also
likely to be going slower than a P47, with turning
more possible. I'm not sure what the power to weight
ratio is unloaded (I presume BP_Machine would have
dumped his bombs). Also the wing design might allow
flight closer to the stall than the P47 with control?

What is tricky about the P47 is that if you yank
the stick in the turn it stalls out. If you sort
of let it find its own way round, the turn isn't
too bad - you just need to make sure the AoA never
gets too high.

XyZspineZyX
09-01-2003, 11:46 AM
RAF74BuzzsawXO wrote:
- Powerloading is only a factor for the first few
- seconds. After that, gravity and drag become much
- more important. And the fact that aircraft very
- quickly reach their limit dive speed. After a dive
- of a few thousand feet, all aircraft reach their
- terminal dive speed. (unfortunately in FB, dive
- acceleration seems very slow and it takes much
- longer to reach terminal speed)

That's my understanding of aerodynamics too. The total
drag on a P47 (lower drag coefficient but larger
wetted area) would have been roughly similar to a 109
at the same high speed (I don't have the numbers to hand)
but the P47 weighs rather more, so gravity is on its side.
This will give more downwards motive power to the P47,
and the drag would balance this out at a higher speed.

Two other planes with good dive performances in WW2
were the 190 and Tempest. All were relatively heavy
planes. The P47 may have outdived the Tempest, although
the Tempest probably had the edge in power:weight ratio,
but the P47 was heavier AFAIK. Certainly low down
the Tempest was faster than the P47D, and the Tempest II
almost as fast as the P47M even at altitude.



Message Edited on 09/01/0310:47AM by AaronGT

XyZspineZyX
09-01-2003, 11:52 AM
Btw, I still suspect that a part of the advantage of the
ruggedness of the P47 may have been due to enhanced pilot
protection rather than any magic in the rest fo the
structure. The RAF did a survey of 845 downed aircraft in
about 1942, and the conclusion was that the injury or death
of the pilot accounted for nearly half of the losses
of aircraft, even if the plane could otherwise have
continued. With excellent pilot protection a P47 could make
it home on the basis that the pilot was still alive, when
in another type of aircraft, he would have been killed.

Another issue might be that if your plane is damaged over
enemy territory then there is an advantage in trying to
make it back. If you are over friendly territory (e.g.
BoB, LW in 1944) then it is easier to return to your home
base, but on the other hand if you bail out, you aren't
going to be captured. It would be basically impossible to
quantify what effect this had on encouraging allied pilots
in whatever aircraft type to try and remain onboard and
make it home.

XyZspineZyX
09-01-2003, 05:15 PM
AaronGT wrote:
- Two other planes with good dive performances in WW2
- were the 190 and Tempest. All were relatively heavy
- planes. The P47 may have outdived the Tempest,
- although
- the Tempest probably had the edge in power:weight
- ratio,
- but the P47 was heavier AFAIK. Certainly low down
- the Tempest was faster than the P47D, and the
- Tempest II
- almost as fast as the P47M even at altitude.

You forgot to mention the F6F and F4-U. /i/smilies/16x16_smiley-wink.gif

XyZspineZyX
09-01-2003, 05:18 PM
RAF74BuzzsawXO wrote:
- Salute
-
- Write Oleg and tell him about the damage issue.
- Magic bullet, plus the question of the turbocharger
- being knocked out and killing the engine... didn't
- happen that way.
-
-

Salute Buzzsaw,

I have written Oleg on this and hope to someday get a reply. /i/smilies/16x16_smiley-happy.gif But as far as the magic bullett is concerned I have too agree that it affects the whole game not just the Jug. But the turbo-supercharger is a blatant error that I have high hopes they are working to address. As far as the ruggedness of the Jug I have to agree that alot of it had to do with pilot protection. Another point on that is the plane had all metal contol surfaces and it's general frame and construction was heavy all metal(Alot to do with her portly weight). I still lover her and if they get these issues worked out that make's it even better.
~S!
Eagle
CO 361st vFG

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XyZspineZyX
09-01-2003, 05:28 PM
AaronGT wrote:
- The relatively indifferent climb and acceleration
- are
- at least fairly accurate. The climb until late on
- with additional power and paddle props was pretty
- ordinary. It's not going to be like a 109K4 in terms
- of sustained climb.

No, nor should it. Nor should just about anything really. lol

I'll put it the way El did. Virutally no pilot in WWII would have preferred the P-39 over the P-47, how does that compare to FB?

The problem isn't that it can't sustained climb with the 109s and La's, its that it can barely get out of it's own way. Yeah, I know it was heavy, I know it was bulky, but it also had a huge 4 bladed prop mated to an engine that, with water injection, was making around 2500hp. I can't help but think that if it had a little more "oomph" it would make things like zooming and ACM easier and more accurate.



-- The gun spread
-- is criminal. There is no reason for it to be as bad
-- as it is.
-
- Do we know if it is accurate or not? It might be
- accurate?

The M2 was accurate. The only thing that could be said was that possibly having 8 of them rocked the boat and threw the spread wide. However, a plane with _that_ much mass? Seems highly questionable.

But, for something more concrete, look at the P-40. Lighter, and only 2 fewer guns. Yet, it's accurate. So....why is the Jug cursed with such a wide spread? Even with only using half it's guns BTW. It's better with 4, but not by much.


- The He-111 was nimble for its size, and is also
- likely to be going slower than a P47, with turning
- more possible. I'm not sure what the power to weight
- ratio is unloaded (I presume BP_Machine would have
- dumped his bombs). Also the wing design might allow
- flight closer to the stall than the P47 with
- control?

Nimble for it's size, yes, however, it's a huge, multi-crewed, multi-engined bomber. One that, aerodynamics aside, almost certainly wasn't engineered for aerobatics from a structural point of view. However, until someone like Kweassa or such can explain to me how such a plane was actually more nimble than a smaller, lighter plane like the P-47, I will remain skeptical of the accuracy of what I experienced (w/r/t realism).


- What is tricky about the P47 is that if you yank
- the stick in the turn it stalls out. If you sort
- of let it find its own way round, the turn isn't
- too bad - you just need to make sure the AoA never
- gets too high.

What constitutes too high? For this plane, in this sim, it really seems to be about 4 or 5 degrees. Even with 500kph it's near impossible to black out in this thing.

XyZspineZyX
09-01-2003, 05:32 PM
Eagle_361st wrote:
- Salute Buzzsaw,
-
- I have written Oleg on this and hope to someday get
- a reply. /i/smilies/16x16_smiley-happy.gif But as far as the magic bullett
- is concerned I have too agree that it affects the
- whole game not just the Jug. But the
- turbo-supercharger is a blatant error that I have
- high hopes they are working to address. As far as
- the ruggedness of the Jug I have to agree that alot
- of it had to do with pilot protection. Another point
- on that is the plane had all metal contol surfaces
- and it's general frame and construction was heavy
- all metal(Alot to do with her portly weight). I
- still lover her and if they get these issues worked
- out that make's it even better.
- ~S!
- Eagle
- CO 361st vFG

Would be nice if we were given manual (including slider) control of the waste-gate too. I can't help but wonder if that was omitted because it might give the plane some capabilities. /i/smilies/16x16_smiley-indifferent.gif

XyZspineZyX
09-01-2003, 05:57 PM
Huckebein_FW wrote:
then the
- pilot should pull out fast because P-47 was
- extremely hard to pull out of dives at speeds over
- 500mph. This is the reason why it was fitted with
- dive flaps.

Of course any plane becomes harder to pull out of a dive as speed increases. But the P-47 was not really any harder to pull out of a dive than any other plane. If it had a problem it was that it could accelerate in a dive very quickly, reaching critical mach in a very short time. This presented a problem in that compressibility sets in sooner at high altitiude than it does at low altitude. So pulling out of a high speed dive at high altitude could present a problem if the plane was traveling in excess of its critical mach. Dive flaps helped with this. Otherwise, the pilot sometimes had to wait until he got to lower altitude, where the air was thicker, to effect his pull out.

Regards,

SkyChimp

http://members.cox.net/rowlandparks/corsairs.jpg

XyZspineZyX
09-01-2003, 06:02 PM
Huckebein_FW wrote:

- Dive performance is not a function of wing load

This is incorrect. Wing loading is absolutely crtitical in dive ability. One of the biggest problems encountered by the Japanaese Zero was it's inability to dive with American planes. The main reason was its very low wing loading.

Regards,

SkyChimp

http://members.cox.net/rowlandparks/corsairs.jpg

XyZspineZyX
09-01-2003, 07:03 PM
In the book THUNDERBOLT!, the stick forces in the P-47 were so great in a high-speed dive that it was compared to being set "in a bucket of concrete."

This would be true of virtually any aircraft of this era that approaches or exceeds it's critical mach in a dive.

In "JG-26 Top Guns of the Luftwaffe" it records how FW190 pilot Peter Crump went into a vertical dive from over 30,000ft. The wings became covered in condensation and the airspeed indicator was pegged. Crump likely exceeded 560 mph in this dive. But he was experienced enough to know not to try a pullout and overload the wings at higher altitudes. At 1,000ft. he was back in level flight.


In FB, it sure does seem like those lightweight Yaks can stay with the heavier fighters quite well in a dive.


<center><img src= "http://www.luftwaffepics.com/LCBW4/FW190-A0-52.jpg" height=215 width=365>

<center>"We are now in a position of inferiority...There is no doubt in my mind, nor in the minds of my fighter pilots, that the FW190 is the best all-round fighter in the world today."

Sholto Douglas, 17 July 1942

XyZspineZyX
09-01-2003, 07:20 PM
Quite many quesses none of them completely correct. You may believe it or dispute it but:

The wing loading has a meaning, anybody with some gliding experience knows it after flying a glider with and without ballast. (In this case the relative wingload increase is, however huge). Thus a big change is notable in the _same_ aircraft. Aerodynamics can just as easily turn it other way around.

It is however, not a) only factor b) the most important factor. Power loading has a big role in the equation as well. According to normal energy principle weight plays no role. However, looking at level flight acceleration different planes, they accelerate differently and this is largely a power loading factor. Level flight acceleration can be just as easily superposed on gravity acceleration.

After level flight top speed has been reached it is a question of how long the prop can produce thrust at all, overrevving is not modeled in the game but is present in RL. Another thing is prop going supersonic, a factor that is not present either,

Summarizing this and loosely projecting on P-47...It has comparably bad power loading at low altitude and bad level flight acceleration due to this (and aerodynamics as well). The only place thus to look for an universal superiority is at high alt where power loading starts being comparable. It has a comparably high level flight top speed and second place to look for a superiority is at dive with a higher speed than this (or rather at speed higher than opponents top speed, after this speed he's effectively bleading E).

At low level with moderate dive speeds (up to some 500-550 km/h) P-47 is not doing very well, compared with for example Yak-3. Furthermore, P-47 diving capabilities are not just simply acknowledged by both sides. These are exactly two most common errors most of the fans do and then come out with FM is wrong criticism. Additionally, some seem to try the diving trick with relatively lower energy level after getting bounced, funny that it does not work.

The game has its shortcomings in the engine modeling, particularly as far as the prop is concerned. In the current version the relative diving performance and limitations are somewhat corrected by low structural limit speeds for some aircraft. This is a factor that places some constrains to diving, real constrain may have been something else, like a runaway prop.

This is I believe what kweassa meant.

However, before "fix this make a realistic prop model", you would just need to know how fast prop turns in each and every aircraft (governor gear ratio), diameter of the prop and of course how fast the control (let it be CS or Kommandoger¤t) can adjust the pitch. Additionally you would need to know the blade design and the efficiency curve. As far as most of the gamers want to have anything from batman to wright flyer integrated into game there is snowball's change in hell to get all of this correct. Once again it is shown that realism is linearly limited with the amount of flyables.

http://people.freenet.de/hausberg/schimpf.gif



Message Edited on 09/01/0308:03PM by Ugly_Kid

XyZspineZyX
09-01-2003, 08:17 PM
Salute 190Fan

Exactly what speed was the P-47's controls reported as feeling like they were in a "bucket of concrete"?

Likely at very high speeds.

You report that the 190 was dived to 500 mph as though this is something impressive. NOT.

The first P-47C (41-6066) was completed on September 14, 1942. Even though the P-47C incorporated strengthened tail surfaces, the P-47C still had some problems in
recovering from the very high dive acceleration and terminal speeds which could be achieved with the P-47. The aircraft was rated capable of diving to 500 mph, (800kph) safely. However because the aircraft accelerated so fast, it could reach speeds beyond 500 mph. Beyond that speed, recovery from power dives was hazardous, with the elevators being unable to respond because of compressibility forces.

(note: Many German or Soviet Fighter aircraft could not even reach 500mph without disintegrating. The fact that the P-47 was able to maneuver up to 500mph is indicative of its excellent high speed characteristics even in the early P-47C model)

The engineers at Republic took a number of steps to improve the aircraft's ability to respond at high speeds.

The P-47C-1-RE production block differed by having an extra 8-inch section added
to the fuselage forward of the firewall to change the center of gravity and giving improved flight characteristics.

Additionally, Bob weights or counterbalance weights were installed in the elevator control system, to help to overcome the compressibility problems that had made high speed dives in the earlier P-47C dangerous.

These bob weights allowed additional leverage to be applied to the P-47's elevators, leverage which was enough to move them, at 500mph or higher despite compressibility effects.

The P-47, like the FW190 also had its aileron, elevator and rudder surfaces moved by control rods, not wire cables. These allowed more leverage to be applied and were no subject to stretching.

On November 13, 1942, Test Pilots Lts. Harold Comstock and Roger Dyar managed to reach airspeeds of 725 mph during high-speed dives in their later model P-47Cs. This was beyond the speed of sound, which, if accurate, would have made them the first pilots to break the sound barrier. However, it is likely that the airspeed readings were inaccurate, since the terminal velocity of the P-47 is about 600 mph. Still it is clear they reached the 600mph range. (960 kph)

The fact that they were able to reach these very high speeds, and recover safely from them, shows the effectiveness of the Elevators on the modified P-47C-1RE.

In some cases P-47's would enter compressibility at high altitudes in a dive, but would ALWAYS recover elevator control when more dense air at lower altitudes was encountered.

The P-47 also had all metal coverings on its control surfaces, ie. ailerons, elevators and rudder. This was an advantage over aircraft with fabric covered control surfaces, which were subject to distortion at high speeds, ballooning etc. The P-47 did not have this problem at high speeds.

The book "America's Hundred Thousand" says that the aircraft had very light controls at most speeds, in fact the stick forces became lighter at higher speeds. According to this source, a modern evaluation gave a stick force of 7.5 lbs per G.

The P-47 had modifications to the elevator controls which designed to give better response at high speeds.

The later mode P-47 from the C-1RE onwards suffered from no serious problems at high speeds.

It had an official maximum allowable dive speed of 550mph IAS (880 kph) below 10,000 ft listed in its manual.

With the advent of the bubble top P-47, and its higher horsepower engine, dive acceleration increased again. Again a redesign with the addition of dive recovery flaps allowed for recovery from even very high speed dives in these models.

Pilots could routinely take their aircraft up to 550 IAS and recover without any problems.

In fact vertical dives from high altitudes up to extremely high speeds were used by P-47 pilots as techniques to catch Me262's. This was well known to the Luftwaffe pilots who flew the jets

Here is a description from Johannes Steinhoff's book, "The Last Chance". Steinhoff flew in JV44 during the last months of the war. Here is an account from his wingman Fahrmann of being shot down by P-47's.

"The black dots in the cruelly bright sky above him were "Thunderbolts". The realization went through him like an electric shock, and while his mouth went dry and his heart began to beat wildly the salt sweat ran out from beneath his helmet and stung his eyes. The Thunderbolts - American fighters we feared because of their extraordinary ability to attack in a nose dive - had spotted an easy prey, and as they immediately pointed their noses to the ground... He flew at high speed into the thin yellowish veiils of mist and realized immediately that his hope of escaping from the pack had been in vain. He was down to a couple of hundred meters when the tracer bullets began reaching for him from behind. It all happened very fast. HIs cockpit was lit by a sudden flash as an inciendary bullet exploded just by his head. He registered a searing pain in the back of his neck, was aware of fields whipping past beneath him, and then he saw the row of giant poplars looming up at him..."

The P-47 had the best diving performance of any U.S. or German prop fighter, and was only exceeded by the Tempest on the British side.


RAF74 Buzzsaw

XyZspineZyX
09-01-2003, 09:15 PM
~S!

Oops, gotta disagree with you Aaron, the P-47 had/has a very clean airframe with a much lower Cl ( drag coeffienct) than the 190 and 109), its not far below the P-51 in ranking.

I think the comparison charts on this are archived by NACA that show a comparsion of many of the WW11 fighters.

Last year I attended a presentation at Oshkosh, where the speaker's talk was about this. Don't have copies or I'd post the link here,

A low Cl has a great deal to do with a machine's acceleration in dive and in the vertical, both the Jug and P-40 as present examples should have heart in the throat acceleration. Compressibility, density altitude,and drag then come into play slowing and stopping acceleration as the machine desends.

All the Best:



BPO5_Jinx
C.O. Replacement Air Group
Birds of Prey. 16th GvIAP
http://www.birdsofprey16thgviap.com
http://www.soaridaho.com/Schreder/RS-15/N50GL.html

XyZspineZyX
09-01-2003, 09:43 PM
1. cl is the lift coefficient, not drag. Depending on the purpose, cd (drag) coefficients can be linked to anything (aircraft weight, front shape, total surface, volume and whatever) and therefore you can make almost any aircraft look better than another one in terms of cd.
2. Drag coefficients are pretty worthless to compare the dive performance of two different aircraft since they're artifical values (see 1.) which only have a direct comparison value if all other paramters are same for both aircraft, which is almost never the case for different aircraft types. Dive performance depends on thrust, weight and drag force, and the latter one only plays a minor role compared to the first two as long as speed is low.
3. Wing loading has little effect on dive acceleration the steeper the dive is, and it has no effect when the dive is vertical (zero-g) since wing loading is a value for estimating induced drag, which is zero in a vertical dive and low at high speed. Furthermore, wing loading alone is also just a rough comparison value for different aircraft since a wing's efficiency re induced drag does not only depend on its area, but also on characteristics like aspect ratio or wing profile, which are not covered by wing loading.
4. It still seems that "good dive performance" of the Jug makes people think it could out-accelerate anything because it is heavy. As has already been stated several times (and should be absolutely obvious with even the most basic knowledge of physics), heavy weight makes dive acceleration in a powered dive (thrust > drag) WORSE. Therefore light aircraft, given similar engine thrust and aerodynamics, accelerate BETTER than heavy ones at speeds lower than max horizontal speed (and a little bit above). So the Yak 3 will out-accelerate a Jug easily. Only at very high speed, the Jug will have an edge, also at very high altitude, simply because most other aircraft lose their thrust there while the Jug doesn't. But the high altitude model is not FB's strength, unfortunately.

XyZspineZyX
09-01-2003, 09:55 PM
Salute

You are wrong Ra.

An aircraft in a dive almost immediately exceeds its normal level speed, at which point powerloading becomes irrelevant and Drag and weight are the only factors.

Your suggestion that a Yak-3 will outdive a P-47 is complete nonsense and bears no resemblance to reality. Why do you think Luftwaffe pilots on the East front who flew 190's were coached to use dives to escape from the lighter better powerloaded Soviet aircraft?


RAF74 Buzzsaw

XyZspineZyX
09-01-2003, 10:03 PM
Hmmmpf.

At the start of a dive, powerloading will rule.

However Force = Mass x Acceleration.

Force -- call it Thrust - Drag
Acceleration -- call it Gravity at 10m/s/s
These are for mostly vertical dives, the less steep the less that gravity affects the dive.

Can anyone say that WWII fighters had anywhere near 1G worth of thrust?

Do the math yourself, if you are capable. The same plane with more weight will dive faster before long, period. In the beginning, no. Later, yes. The more extra weight, the longer it takes but the greater the difference as well.

Drag is the other big element that will overcome all. As it has been pointed out, compression doesn't seem to make so much difference in FB. You go too fast and the plane shakes a bit then breaks up like it's an added feature so I don't expect that prop compression is modelled at all.


Neal

XyZspineZyX
09-01-2003, 10:17 PM
RAF74BuzzsawXO wrote:
- An aircraft in a dive almost immediately exceeds its
- normal level speed, at which point powerloading
- becomes irrelevant and Drag and weight are the only
- factors.

What do you mean with 'normal level speed'? Its maximum level speed? Well you are right that it doesn't take long to reach and exceed that speed, but until that time, the lighter aircraft accelerates faster (given everything else is equal [!!!]), which is a dive advantage. After that point, the heavy aircraft gains an edge (and I also wrote this above) and this is one thing people mean when they talk of good dive performance of a Jug; the other thing would be good overall performance, of course including dive acceleration, at high altitude.
In my post I made clear that it does not mean a Jug could out-accelerate any aircraft anytime, which some people seem to believe.

- Your suggestion that a Yak-3 will outdive a P-47 is
- complete nonsense and bears no resemblance to
- reality.

The term "out-diving" covers overall dive acceleration (slow speed + high speed) and maximum dive speed. I, however, was talking about dive acceleration at speeds lower than max horizontal speed, so note the difference.

- Why do you think Luftwaffe pilots on the
- East front who flew 190's were coached to use dives
- to escape from the lighter better powerloaded Soviet
- aircraft?

You must specify which Yak and which 190. Some 190 variants have better power loading than some Yak variants, some have worse. For example, the 190A5 has better power loading than a Yak1B, yet worse than a Yak 3; the 190A4 is inferior to both in this aspect while the A8 again is superior to both Yaks. So if the 190 pilot has a late Yak on his six and not enough separation to overcome the initial dive acceleration advantage of the Yak, then it doesn't help him much that the 190 accelerates better at high speed.
I was saying that a light aircraft with similar aerodynamics and thrust as a heavy one out-accelerates it as long as thrust > total drag (which is true for any speed lower than max horizontal speed), not that a 190 can't outdive a Yak no matter how they start.

XyZspineZyX
09-01-2003, 10:23 PM
SkyChimp wrote:
- This is incorrect. Wing loading is absolutely
- crtitical in dive ability. One of the biggest
- problems encountered by the Japanaese Zero was it's
- inability to dive with American planes. The main
- reason was its very low wing loading.

No, what is critical is the balance of forces -
thrust, weight, lift, and drag.

Wing loading is not a force. The force that is related
to the wings is the induced drag, and aircraft with
larger wings will, all other things being equal, tend
to have larger induced drag.

Wing loading, though, is a function of weight:wing area.
It is a secondary derivative of wing area (to which
induced drag is related) and the weight, or force
due to gravity.

If you have a lot of lift compared to the inertia
(mass) of the aircraft, you would need to apply more
control forces to keep the plane in the dive, which
will also add to the drag.

So a low wing loaded plane will, all other things
being equal, be less good in a dive, but the wing loading
is not the critical factor, just a ratio of two things
to which critical factors are related.

XyZspineZyX
09-01-2003, 10:26 PM
WWMaxGunz wrote:
- However Force = Mass x Acceleration.
-
- Force -- call it Thrust - Drag
- Acceleration -- call it Gravity at 10m/s/s

No,
"Thrust - Drag = Mass x GravitationalAcceleration"
is mixed up. For a vertical dive, it is
"Thrust - Drag + GravitationalForce = Mass x DiveAcceleration"
with GravitationalForce = Mass x GravitationalAcceleration

The rest is obvious if you solve the equation after DiveAcceleration.

XyZspineZyX
09-01-2003, 10:32 PM
Ugly_Kid wrote:
- It is however, not a) only factor b) the most
- important factor. Power loading has a big role in
- the equation as well. According to normal energy
- principle weight plays no role.

That doesn't make any sense to me.

Making some back of the envelope approximations - the
P47 has about 2000hp to play with (slightly more, but
we're not going to get the whole amount transferred
to the air, and either way it doesn't make much odds),
which means 1.5MW

If it is going straight down at a little less than 500mph
that's 200 m/s, and an approximately 5000kg plane. The
potential energy loss is Fd = mad = 5000*10*200, or
about 10MW.

That seems to suggest that the force of gravity is
providing the greater energy input into the system by
about an order of magnitude over the engine. This
tends to support the idea that the mass of the plane
is an important factor.

XyZspineZyX
09-01-2003, 10:36 PM
BPO5_Jinx wrote:
- ~S!
-
- Oops, gotta disagree with you Aaron, the P-47
- had/has a very clean airframe with a much lower Cl (
- drag coeffienct)


Yes, that is indeed exactly what I said! The TOTAL
drag, however, is larger, though, as it has a larger
wetted area, such that it means a bigger total drag
even given that the 109 has a larger drag coefficient.
(We went through this a few months back in
great detail. Skychimp agreed that the 109 had a lower
total drag at typical speeds).

The fact that the 109 has a lower total drag can be
demonstrated by noting that at sea level (where the
rated horsepowers are achieved) the 109 and P47D
achieved about the same speed (circa 355-360mph) although
the 109 had a less powerful engine.

XyZspineZyX
09-01-2003, 10:41 PM
JG5_JaRa wrote:
- 4. It still seems that "good dive performance" of
- the Jug makes people think it could out-accelerate
- anything because it is heavy. As has already
- been stated several times (and should be absolutely
- obvious with even the most basic knowledge of
- physics), heavy weight makes dive acceleration in a
- powered dive (thrust > drag) WORSE.

I have a degree in physics. That makes no sense to me!
So if I am wrong, I'd honestly appreciate an explanation
(I am not trying to be funny, just to learn).

I did a calculation a little way back showing that the
P.E. lost by a plane (and converted into KE) by simply
dropping in a dive is an order of magnitude greater
than the energy output of the engine in the same time
period, hence my confusion about your above statement.

XyZspineZyX
09-01-2003, 10:57 PM
Ok, a step-by-step explanation. We assume a vertical dive. Then (since lift=0), the only forces acting on the aircraft are:
Thrust force (F_t),
Drag force (F_d),
Weight force (F_w).
With the gravitational acceleration (A_g) of 9.81 m/s/s, Newton's "Force = mass * acceleration" looks like this:
F_t - F_d + F_w = m * A_d
with A_d being the dive acceleration.
Then we solve the equation for A_d,
A_d = (F_t - F_d + F_w) / m
or
A_d = (F_t - F_d) / m + F_w / m
with F_w / m = A_g = constant.
Here you see that for F_t - F_d > 0, or in other words Thrust > Drag (which is true for low speed), dive acceleration A_d is higher than gravitational acceleration (= free fall) whereas for Drag > Thrust (high speed), it is lower. So the term (F_t - F_d) / m, in other words "(Thrust - Drag) / Mass", effectively describes dive acceleration. This term will be low when mass is high which is equivalent to the statement that a heavy aircraft, Thrust and Drag being the same as for the light aircraft, accelerates worse at slow speed and better at high speed than the lighter one.

edit: typo

Message Edited on 09/01/0311:02PM by JG5_JaRa

XyZspineZyX
09-01-2003, 10:59 PM
AaronGT wrote:

- Yes, that is indeed exactly what I said! The TOTAL
- drag, however, is larger, though, as it has a larger
-
-
- wetted area, such that it means a bigger total drag
- even given that the 109 has a larger drag
- coefficient.
- (We went through this a few months back in
- great detail. Skychimp agreed that the 109 had a
- lower
- total drag at typical speeds).
-

Yes, I agree that is has a lower TOTAL drag, but comparing TOTAL drag is virtually irrelevent. Comparing total drag, one could argue the Bf-109 was more aerodynamic than a Boeing 707 because the 707 has more total drag. And we know the Bf-109 was not as aerodynamic as the 707.

Comparing Cds is a much better way for compare the aerodynamic properties of planes because Cd is a non dimmensional value. You can compare two planes of unequal size and get a good idea as to how they compare aerodynamically.



- The fact that the 109 has a lower total drag can be
- demonstrated by noting that at sea level (where the
- rated horsepowers are achieved) the 109 and P47D
- achieved about the same speed (circa 355-360mph)
- although
- the 109 had a less powerful engine.

Saying this means very litte. If one were to increase the size of the Bf-109 to a size that was comparable to the P-47, it would need MORE power to achieve the same speed as the P-47. Because at this point, it would have more drag than the P-47.

So yeas, the Bf-109 had more total drag than the P-47. In if looked at in a ratio of drag to wetted area, it would be higher than the P-47.


====================

Another thing most people tend to forget is that Cd rises as speed increases. Most planes will start to experience a significant increase at Mach .6 with the Cd rising dramatically at .8.

Mach .6 is not very fast for a WWII fighter in a dive. Contemporary WWII fighters with lower Cds will general maintain their rates of acceleration in a dive better than those fighters with higher Cds.


Regards,

SkyChimp

http://members.cox.net/rowlandparks/corsairs.jpg

XyZspineZyX
09-01-2003, 11:24 PM
You're back on this BS again chimp? I've never seen anyone hate the 109 so much. It's sad and funny. lol

Your statements were bordering on the ridiculous about total drag being meaningless. Sorry, but it's true.

Total drag is, essentially, how much air an object has to move to get through it. A smaller, less aero object will move less air, and therefore, accelerate faster with a given amount of energy than a larger, but more aero object, because it has to move more air, it has more drag, so it's burning up more of it's input energy.

Aarons comment about the 109 and P-47 top speeds at sea level relative to engine power pretty much says it all.

XyZspineZyX
09-01-2003, 11:54 PM
BlitzPig_DDT wrote:

- You're back on this BS again chimp? I've never seen
- anyone hate the 109 so much. It's sad and funny. lol

Whatever. BTW, I didn't bring the Bf-109 into this conversation. Or didn't you bother to read the whole thread?



- Your statements were bordering on the ridiculous
- about total drag being meaningless. Sorry, but it's
- true.

Actually, not.



- Total drag is, essentially, how much air an object
- has to move to get through it.

"How much air" it has to move is wrong. Drag is the force that opposes thrust.



- A smaller, less aero
- object will move less air, and therefore, accelerate
- faster with a given amount of energy
- than a larger,
- but more aero object, because it has to move more
- air, it has more drag, so it's burning up more of
- it's input energy.

Maybe.

But still you don't seem to grasp it. To simply say the Bf-109 has less total drag than the P-47 means squat. So what. What's that prove? It proves jack $hit.

The Bf-109's drag is NOT a function of the P-47s acceleration, nor vise versa. Total Drag is relevant only to the plane that is in question.

Consider two planes of equal size, both with the same horsepower, but one with less drag. The one with less drag will accelerate at a higher rate.

Consider two planes of differing sizes. Both with the same horsepower, but the larger one has less drag. They very well may accelerate at the same rate. It depends on more than just size.

You have to look at this on a case by case basis and calculate each planes acceleration, taking the drag of each plane into consideration in it own equation.

So your statement that the smaller, less aerodynamic, plane will accelerate better than the larger, more aerodynamic plane, with a given amount of energy [same horsepower?], is NOT necessarily correct.



- Aarons comment about the 109 and P-47 top speeds at
- sea level relative to engine power pretty much says
- it all.

Here's what he said:
The fact that the 109 has a lower
total drag can be
demonstrated by noting that
at sea level (where the
rated horsepowers are achieved)
the 109 and P47D
achieved about the same speed
(circa 355-360mph) although
the 109 had a less powerful engine.

So it had lower total drag. It also has a smaller wetted area, smaller mass... BUT it needed a higher power/weight ratio to achieve the same speed as the P-47 because is was LESS areodynamic. In otherwords, the Bf-109 had more drag as a ratio of its wetted area than the P-47 did. Therefore, its aerodynamic design was less efficient than that of the P-47.

You don't have to love Bf-109s or hate P-47s to see that. That's just the way it is.


Regards,

SkyChimp

http://members.cox.net/rowlandparks/corsairs.jpg


Message Edited on 09/02/0303:04AM by SkyChimp

XyZspineZyX
09-01-2003, 11:59 PM
Assuming equal mass in order to speak only about drag, my statement is true.

You are telling someone with a degree in physics (Aaron) that he's wrong while spouting nonsense and yet claim I don't grasp it? lol Ok dude. Whatever.

Don't worry man, the evil 109s won't come and get you in the night. lol /i/smilies/16x16_smiley-wink.gif

XyZspineZyX
09-02-2003, 12:09 AM
BlitzPig_DDT wrote:

- Assuming equal mass in order to speak only about
- drag, my statement is true.

What does this mean? It's not clear at all.



- You are telling someone with a degree in physics
- (Aaron) that he's wrong while spouting nonsense and
- yet claim I don't grasp it? lol Ok dude. Whatever.

DDT, dude, I'm not saying Aaron is wrong. In fact, he's absolutley correct, the Bf-109 had less total drag than the P-47.

But I am saying simply comparing the total drag of one plane to the total drag of another really means nothing. To get an idea as to each plane's aerodynamic efficiency you have to do more than that.



- Don't worry man, the evil 109s won't come and get
- you in the night. lol

Sigh.



Regards,

SkyChimp

http://members.cox.net/rowlandparks/corsairs.jpg


Message Edited on 09/02/0303:48AM by SkyChimp

XyZspineZyX
09-02-2003, 12:24 AM
AaronGT wrote:

- So a low wing loaded plane will, all other things
- being equal, be less good in a dive, but the wing
- loading
- is not the critical factor, just a ratio of two
- things
- to which critical factors are related.


Understood.

Regards,

SkyChimp

http://members.cox.net/rowlandparks/corsairs.jpg

XyZspineZyX
09-02-2003, 02:53 AM
RAF74BuzzsawXO wrote:

- Salute 190Fan
-
- Exactly what speed was the P-47's controls reported
- as feeling like they were in a "bucket of concrete"?
-
- Likely at very high speeds.


Caiden(sp?) doesn't state it exactly, but high speed is implied of course. Sorry if the "bucket of concrete" quote in a book about the Thunderbolt hurt your feelings, that was not the intent of my post.


- You report that the 190 was dived to 500 mph as
- though this is something impressive. NOT.


Not sure what your little problem is here Skippy, but you were obviously unable to understand the proper context of my post, which was:

(A) Any aircraft of this era would require a significant amount of stick force to recover from a dive that approaches or exceeds it's terminal mach.

(B) Peter Crump in his 560+ mph dive had the experience and discipline not to overload the wings of his aircraft at _high altitude_ critical mach. Dive recovery was made at lower altitudes.

This was basically in agreement with and in support of SkyChimp's earlier post concerning dive recovery at lower altitudes. The type of aircraft and the fact that it was German was basically irrelevant to the point of the post.

The point was, however, lost on you in your knee-jerk reaction to any percieved, implied, or real slight to the P-47.

The fact is, the recorded speeds reached in a dive for the FW190A(which you write off as unimpressive) is right in line with the terminal mach number listed for the P-47, whether you like it or not. I suppose you don't like this because it is a German fighter though huh?



- The first P-47C (41-6066)...


yada yada yada...thank you for sharing.





<center><img src= "http://www.luftwaffepics.com/LCBW4/FW190-A0-52.jpg" height=215 width=365>

<center>"We are now in a position of inferiority...There is no doubt in my mind, nor in the minds of my fighter pilots, that the FW190 is the best all-round fighter in the world today."

Sholto Douglas, 17 July 1942

XyZspineZyX
09-02-2003, 10:11 AM
SkyChimp wrote:
- Yes, I agree that is has a lower TOTAL drag, but
- comparing TOTAL drag is virtually irrelevent.

Er... it is what resists the thrust from the engines
and stops it going any faster. It is totally relevant!

- Comparing Cds is a much better way for compare the
- aerodynamic properties

Yes, _aerodynamic properties_ but the total drag,
which also depends on the wetted area is somewhat
more relevant for determinations of things like
maximum attainable speeds, since the total drag
is the force that resists the thrust.

- Saying this means very litte. If one were to
- increase the size of the Bf-109 to a size that was
- comparable to the P-47, it would need MORE power to
- achieve the same speed as the P-47.

Exactly! Well spotted. But the 109 is smaller.

- So yeas, the Bf-109 had more total drag than the
- P-47.

I think you mean less, but I think that was just
a typo!

- Another thing most people tend to forget is that Cd
- rises as speed increases.

The drag coefficient is a pretty approximate way
of measuring the aerodynamic properties of an
aircraft. Lots of the equations used to determine
aerodynamic behaviour are also any good for laminar
flows, and at higher speeds you can get detachment
of eddies, and all sorts of other non linear effects.
After all, if Cd was all there was too it, there would
be no need for windtunnels, or 512 node beowulf systems
for doing computational fluid dynamics calculations
for the aero industry.

XyZspineZyX
09-02-2003, 10:19 AM
SkyChimp wrote:
- But still you don't seem to grasp it. To simply say
- the Bf-109 has less total drag than the P-47 means
- squat. So what. What's that prove? It proves jack
- $hit.

It shows how much drag there is on the airframe. It is
a very important factor. I don't know why you don't
understand this.

- Consider two planes of equal size, both with the
- same horsepower, but one with less drag. The one
- with less drag will accelerate at a higher rate.

Yes...

- Consider two planes of differing sizes. Both with
- the same horsepower, but the larger one has less
- drag. They very well may accelerate at the same
- rate. It depends on more than just size.

Yes...

And in the case of the 109 we have a plane with less
drag than the P47, and a bit less horsepower, but
lower weight, and a little less inertia.

The Cd of the 109 is higher than the P47, but its
total drag is lower.

- So your statement that the smaller, less
- aerodynamic, plane will accelerate better than the
- larger, more aerodynamic plane, with a given amount
- of energy [same horsepower?], is NOT necessarily
- correct.

On the whole, as long as the delta v
is relatively small, such that the Cd for each plane
remains relatively constant throughout the speed
increase. The smaller, less aerodynamic aircraft, with
a lower total drag will have a lower force resisting
its movement, as well as lower inertia.

Basically we have F=ma, where F=T-D (thrust - drag).
or T-CdA=ma. So if the total drag CdA is lower, the
thrust is the same, and the mass of a smaller plane
lower then a=(T-CdA)/m would be higher.

- So it had lower total drag. It also has a smaller
- wetted area, smaller mass... BUT it needed a higher
- power/weight ratio to achieve the same speed as the
- P-47 because is was LESS areodynamic.

Absolutely. This is what I said.

- In
- otherwords, the Bf-109 had more drag as a ratio of
- its wetted area than the P-47 did. Therefore, its
- aerodynamic design was less efficient than that of
- the P-47.

But what Blitz Pig said isn't about its efficiency,
just the amount of drag relative to the power put
into the system. The relative efficiency of the
design isn't particularly relevant at sea level,
straight and level, at a steady state.

XyZspineZyX
09-02-2003, 10:26 AM
SkyChimp wrote:
- DDT, dude, I'm not saying Aaron is wrong. In fact,
- he's absolutley correct, the Bf-109 had less total
- drag than the P-47.


I think we are all getting a bit testy and heated about
this. I think half the problem is that it is easy to
misunderstand what people mean on this forum, even for
the native English speakers! It's probably one of those
arguments that could be solved in 10 minutes in the pub
with a pen and a few pieces of paper.

We all need to chill out I think, me included.

- But I am saying simply comparing the total drag of
- one plane to the total drag of another really means
- nothing. To get an idea as to each plane's
- aerodynamic efficiency you have to do more than
- that.

I just wasn't concerned about the aerodynamic efficiency,
just the total drag. I can't remember how it came up exactly
now, but I think was just mentioning that the total drag on
the P47 is about the same as the 109, but given that it
weighs more, we should probably expect it to outdive the 109.
Initially at shallow angles, the 109 has an advantage
in terms of power:weight ratio (engine power balances weight
balances for the P47 at about a 15 degree dive angle).
But then as Cd is a function of v, we'd
expect the 109's total drag to probably increase faster as v
increases as it is a less clean design, with more issues
with boundary layer separation etc, no doubt. In addition
as dive angle increases, the P47 puts more of its brute
weight into the equation, as it were.

So I suppose as v increases, Skychimp is right to be
concerned about aerodynamic efficiency.

XyZspineZyX
09-02-2003, 12:21 PM
AaronGT wrote:
-
- Ugly_Kid wrote:
-- It is however, not a) only factor b) the most
-- important factor. Power loading has a big role in
-- the equation as well. According to normal energy
-- principle weight plays no role.
-
- That doesn't make any sense to me.
-
- That seems to suggest that the force of gravity is
- providing the greater energy input into the system
- by
- about an order of magnitude over the engine. This
- tends to support the idea that the mass of the plane
- is an important factor.
-
-

I am sorry for my formulation which may be hard to follow. Energy priciple, conversion potential to kinetic energy, mass plays no role, the final velocity is v=sqrt(2*g*h) h being the height. However, this would mean leaving aerodynamics and thrust aside. And yes, gravity is much higher than the thrust and the drag BUT gravitional acceleration is g just the same for heavy and for light.
Just as JaRa put it before max. level flight speed thrust>drag and dividing this force balance by greater mass has relatively negative effect. After top speed it has a positive effect. Before top speed dive acceleration > gravity acceleration, after that it's below.


Now Jara put it extremely well. I just hate to make even a slightest correction, the first point about wing loading. Wing loading plays role even in a 90? dive, because profile drag force would be D=0.5*roo*V^2*S*Cd0, thus dividing this with mass to get an acceleration it is linearly dependent on wing loading. On induced drag part he was spot on, this is reduced with dive angle, thus working for a heavier wingloaded plane (which flies in the initial stage with a higher lift factor). This part plays anyway a minor role because the area of induced drag influence is left quite rapidly.

Now if you start at low level at low speed (below 400 km/h) and try to escape Yak-3 by diving you will get hammered. This is a situation where you should never be in the first place. If you let your speed drop below 400-500 km/h you'd better make pretty sure that there's no-one within the approximaty. This applies to FW just as well. If you place criticism on P-47 diving starting from this scenario you're having utopistic expectations. Adding that Yak-3 is about 3 times more efficient than P-47 aerodynamically...

I put couple of equations so that those with interest can play around:

http://people.freenet.de/hausberg/dive.gif


As the second term in acceleration shows, power loading is present. As the the third term shows, wing loading is present. In a glider without engine the second term would be zero leaving an interesting outcome, wing area being equal mass and Cd0 have equally important role.

At level flight top speed second and third term are equal Thus it can be concluded that below that speed with bad aerodynamics (let it be flat plate efficiency), high wing loading and bad power loading you're three times screwed. Yak-3 is probably the most efficient aircraft in all three counts in the game (having also quite a high level flight top speed). Thus outdiving is a relative term having interesting implications.

You also have to note that below top speed acceleration is rapid (greater than from gravity alone), yes but so is the relative change in the speed and so is the relative difference. After that speed the changes are slower (less than gravity acceleration) and so is the relative speed change (speed change per time unit related to the current speed), thus gain at lower speed comes faster.

Whereas the prop efficiency below top speed can be still estimated it is hard to know how good it was above that speed. The open questions are 1) what kind of acceleration did the prop tolerate without overrevving (did P-47 CS react faster than Yak-3?, for example), 2) did they have to throttle back? 3) Did the prop go supersonic at some stage causing a drop of thrust?

-------------------------------------
http://people.freenet.de/hausberg/schimpf.gif



Message Edited on 09/02/0312:22PM by Ugly_Kid

XyZspineZyX
09-02-2003, 01:33 PM
Ugly_Kid wrote:
- Wing loading plays role even in a 90?
- dive, because profile drag force would be
- D=0.5*roo*V^2*S*Cd0, thus dividing this with mass to
- get an acceleration it is linearly dependent on wing
- loading.

Right, total drag is a function of surface and thus also of wing loading since wing loading depends on surface but parasite drag does not depend on mass of course. I was (nit pick...) having wing loading as a term approximately describing induced drag in mind and induced drag is zero in a vertical dive. That's why I was referring to the forces directly and not to values derived from them.
But the word(s) of wisdom in your sig pic describe the whole issue very clearly /i/smilies/16x16_smiley-very-happy.gif

XyZspineZyX
09-02-2003, 02:27 PM
I did not know you mastered physics AND boarisch /i/smilies/16x16_smiley-happy.gif , the quality is raising dramatically - I considered it as an appropriate sig in the very essence of this forum.

Sorry for the nitpicking, your explanations were absolutely great and quite clear. (hopefully I did not add to the confusion with too much blabla/i/smilies/16x16_smiley-happy.gif )

-------------------------------------
http://people.freenet.de/hausberg/schimpf.gif

XyZspineZyX
09-02-2003, 02:59 PM
JG5_JaRa wrote:
- Ok, a step-by-step explanation. We assume a vertical
- dive. Then (since lift=0), the only forces acting on
- the aircraft are:
-
- Thrust force (F_t),
- Drag force (F_d),
- Weight force (F_w).

Weight Force is Mass x Gravity as in F = M x A
Weight is only the effect of Acceleration on Mass, ever.
Weight is the Force.

- With the gravitational acceleration (A_g) of 9.81

oooh, I did round up back there. Good thing I did no math with it!

- m/s/s, Newton's "Force = mass * acceleration" looks
- like this:
- F_t - F_d + F_w = m * A_d
- with A_d being the dive acceleration.

So now you have Thrust - Drag + Mass x G = Mass * Accel

At terminal speed, Accel = 0, the other components cancel each other.

- Then we solve the equation for A_d,
- A_d = (F_t - F_d + F_w) / m
- or
- A_d = (F_t - F_d) / m + F_w / m

And here you are wrong.

=================================================
(thrust - drag + mass x G) / mass

does not equal

(thrust - drag) / mass + (mass x G) / mass
=================================================

If that worked for real then algebra would always be a snap. The terms in the () must be solved before any division by mass takes place. Thrust and drag are related to weight as mass x gravity in full, their effect is scaled to that before dividing by mass in the way of inertia.

- A_d = (F_t - F_d + F_w) / m

accel = ((thrust - drag) + weight) / mass in vertical dive

One more time... will you tell me that any WWII Fighter had enough thrust to equal or come close to holding its own weight? Name for me a WWII prop fighter that could hold itself up by thrust alone?

I really don't believe that you can begin to call mass a non-factor or unimportant in a dive from any speed. You certainly cannot divide it out as you tried.

Thrust/Mass is very important in a dive at least before Drag approaches Applied Thrust, I will not begin to dispute that.

Realities: These dives rarely began as vertical. Gravity assist is smaller with shallowness of dive. These dives, running from another plane, may begin at any speed. Low speed and vertical... from the top of a hammerhead turn? How fast can a plane get into a steep dive without doing something severe enough to bleed speed if it's at all possible to go from level to steep dive that fast? For sure the transition is part of any tests from which data is available? How soon into a dive before anyone would be throttling down to prevent blowing their engine? The faster the plane moves, the less efficient the prop -- how far into the dive before maximum power to weight ratio is meaningless? In a vertical dive, how long before your favorite plane approaches what is high speed for it? i am guessing the answer is pretty damn soon!

Compare the acceleration you get flying level to even a shallow dive. Is the difference due to less induced drag from lift? No. It is due to gravity assist using the mass of your plane. If your plane weighed 20% more, don't you think that you would have more speed increase? Your drag would be the same. The extra mass would only slow down the time to gain that speed and then only the thrust component would truely be impacted with weight (gravity x mass) having a moderating effect even then.

You want to compare planes then you don't need to hoke up some equations. Especially when you don't plug in any values but then when one can dismiss mass in a dive then who needs numbers? How about drag up some data? Perhaps Oleg has some dive data that can be released and maybe he could say how those values compare to what he has accepted without compromising his other sources and agreements? It would be interesting.


Neal

XyZspineZyX
09-02-2003, 03:12 PM
I expect a summary statement when you guys are done, ok? http://ubbxforums.ubi.com/infopop/emoticons/icon_smile.gif

S!
609IAP_Recon

Forgotten Wars Virtual War
Forum: http://fogwar.luftwaffe.net/forums/index.php
Website: http://forgottenwars.dyndns.org
Visit 609IAP at http://takeoff.to/609IAP

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Agnus Dei, Qui Tollis peccata mundi, Miserere nobis. Dona nobis pacem

XyZspineZyX
09-02-2003, 03:19 PM
Neal, no need to get sarcastic here. The equation I set up above is so simple and straightforward that I'm surprised how it can be so confusing. And it is totally accurate by the definition of the forces I used. No here and there, no what if and no approximations are needed. Please read carefully what I wrote.
Let me try to put some things in words again, although formulas are always much more precise and clear to understand, I hope that my sometimes poor english is precise enough for this.
Without thrust and drag (in a vacuum), all aircraft dive at the same acceleration (9,81 m/s/s and btw I didn't write this because I wanted to say your 10 m/s/s are wrong so stay cool - I just think that 9,81 rings a bell for more people).
With air drag but no thrust, a heavy aircraft outdives a lighter one, simply because its higher mass means higher inertia against the air drag force which tries to slow it down.
Once we add thrust and thrust is stronger than air drag (and not stronger than weight as you wrote - I never said that, read carefully!), then the higher inertia of the heavy aircraft will lessen this acceleration effect, just as it lessens the braking effect of drag in a no-thrust dive. Once drag becomes higher than thrust, the high mass will again lessen this braking effect and the heavy aircraft gets an advantage.
If you want to go deeper into drag forces, you can start with Ugly_Kid's equations but in my case, since I assumed same drag for both aircraft, no further investigation is necessary.
For non-vertical dives, the equation has to be modified by introducing induced drag which is, however, very small for high speeds and low g (around 1g in a shallow dive).

XyZspineZyX
09-02-2003, 03:23 PM
by the way,

WWMaxGunz wrote:
- And here you are wrong.
-
- =================================================
- (thrust - drag + mass x G) / mass
-
- does not equal
-
- (thrust - drag) / mass + (mass x G) / mass
- =================================================

You're not serious about this, right?

XyZspineZyX
09-02-2003, 03:44 PM
men do you try late war 109 models like G10,K4,G14,G6/as you will have same problem you seems to fly a truck when boom and zooming and everybody hear you coming from behind because of sound now you'll now what it made to fly LW plane haha and with late war 109 model exept K4 the climb rate is very poor.


Recon_609IAP wrote:
- Maybe #2 is causing me to think this way. It isn't
- 'turning' that I am talking about, simple mobility -
- it's got a heavy feel for sure, but not very
- responsive imo.
-
- ie. BnZ dive. Very difficult to compensate for any
- jink by a bandit. (Especially with this silly sound
- bug where they hear you coming). Robert Johnson
- talks of the vector roll, etc.. and I get a sense
- that a p47 could compensate better on adjustments
- made in this example.
-
-
- I used the word immobile to avoid any talk of
- 'sustained turns', etc..
-
- I'm a bnz oriented pilot and yet still find the p47
- lacking in general overall mobility. (I use the p47
- D10 model - still find the view to be pretty bad --
- almost as bad as the 190's) - granted it climbs
- better in 1.1b, but still is like flying a 747 :P
-


<A HREF=http://www.normandieniemen.firstream.net/</A>pilotes/profils/enigmus.jpg">


NN_EnigmuS.
Normandie Niemen virtuel.
http://www.normandieniemen.firstream.net/

XyZspineZyX
09-02-2003, 03:44 PM
Acceleration in dive or zoom climb is

acc = (T-D)/m - sin(angle)*g

where

T - thrust
D - total drag
m - weight
g - gravitational acceleration
angle - angle of dive/zoom, if it is dive note it with minus in front (like -30 degrees) if it is zoom climb leave it positive.


(T-D)/m is almost acceleration in level flight, just a little bit bigger, because induced drag is smaller in dive;

(T-D)/m in level flight is almost 4.5m/sec^2 on take off, decreases to 2m/sec^2 at 400km/h is 0 at max speed on best accelerating planes like K4 and La7; it decreases almost linearly. Keep in mind that most ww2 fighters had half the acceleration of K4.

Now let's corelate this with dive acceleration - you see that for example at 400km/h and 30 degrees dive a K4 accelerates with 2 + 9.81/2 = aprox 7 m/s^2

The interesting fact is that another plane, with less good acceleration can put the same diving acceleration by symply increasing the dive angle, and this increase is actually quite small - let's say we have a plane with a normal 1 m/s^2 acceleration at 400km/h, now if we put it in a 40 degrees dive we'll get 1 + sin(40)*9.81 = 1 + 0.64*9.81 = slightly more than 7 m/s^2, which means more than K4

In conclusion, if you have a fighter that has a higher max speed or higher critical Mach number but it does not have a good level acceleration, make the dive at a steeper angle than your opponent.


<center> http://www.stormbirds.com/images/discussion-main.jpg </center>

XyZspineZyX
09-02-2003, 04:32 PM
RAF74BuzzsawXO wrote:
-
- (note: Many German or Soviet Fighter aircraft could
- not even reach 500mph without disintegrating. The
- fact that the P-47 was able to maneuver up to 500mph
- is indicative of its excellent high speed
- characteristics even in the early P-47C model)
-

What 'many German or Soviet Fighter aircraft' you are talking about exactly ? Leave the usual generalised BS at home, will ya?

As for German fighters go, dive test with 109F I have show 906 kph (562mph) and Mach .805 reached without the slightest sign of disintagration, and British reports also tell about FW 190A reached 580 mph and didn`t have any problems. Should be mentioned that both planes were relatively lighter and lower powered versions of their kind, hence their dive performance was also worser.



-
- The P-47 had the best diving performance of any U.S.
- or German prop fighter, and was only exceeded by the
- Tempest on the British side.
-

Hmm, Tempest outdiving the P-47 ? I have never saw a reference to that. However, I saw reference between tests with an old 109G-2 regarding dive capabilites vs. the Tempest V :

"Dive
Initial acceleration of the Tempest is not marked, but a prolonged dive brings the Tempest well ahead. "


Which pretty much shows that planes with high weight but low powerloading are pretty much at disadvantage vs. lighter types at the beginning of the dive, and can only take advantage after while.


Note also, that German tests with 109G-6 dived vs. P-47D resulted the latter being "somewhat better" ("etwas besser", exact wording) in dives. If the massive advantage due to weight and thrust alone would exists in dives, this test should show something different, shouldn`t it?

http://vo101isegrim.piranho.com/FB-desktopweb.jpg
'Only a dead Indianer is a good Indianer!'

Vezérünk a Bátorság, K*sérµnk a Szerencse!
(Courage leads, Luck escorts us! - Historical motto of the 101st Puma Fighter Regiment)

Flight tests and other aviation performance data: http://www.pbase.com/isegrim

XyZspineZyX
09-02-2003, 04:49 PM
SkyChimp wrote:

- Comparing Cds is a much better way for compare the
- aerodynamic properties of planes because Cd is a non
- dimmensional value. You can compare two planes of
- unequal size and get a good idea as to how they
- compare aerodynamically.

Which brings us to that most NACA-inspired Cd values are relative to wing area only, which alone makes Cd - or aerodynamic quality - comparisons incompatible. Simply because the amount and percentage of the total drag created by the wings is very different on different designs, ie. a P-51`s wings may be responsible for 15% of the total drag, whears on a, say Spitfire, with very similiar wing area it can be as much as 30%. Yet, you compare ALL DRAG vs. only a selected area which doesn`t share the same "responsibility" for it on different designs.

This being said, you are already comparing incompatible things, and the whole comparision doesn`t makes much sense, unless you are comparing two planes that are exactly the same, EXPECT for their wings.

In fact, the SCIENTIFIC, internationally accepted way of measuring aerodynamic shape is always related to the frontal surface of the object relative to it`s equivalent flat plate drag area.

http://vo101isegrim.piranho.com/FB-desktopweb.jpg
'Only a dead Indianer is a good Indianer!'

Vezérünk a Bátorság, K*sérµnk a Szerencse!
(Courage leads, Luck escorts us! - Historical motto of the 101st Puma Fighter Regiment)

Flight tests and other aviation performance data: http://www.pbase.com/isegrim

Message Edited on 09/02/0305:53PM by Vo101_Isegrim

XyZspineZyX
09-02-2003, 06:03 PM
Huckbein FWs quote ....." P-47 had a bad power to weight at low altitudes and better than most at altitude - for this reason P-47 was outdived at low altitude and outdived most at high altitude"..... ok huckleberrybein gets the award.... please frame this in your trailer in your park huckbein.... "STUPIDEST POST OF THE MONTH AWARD" congrats you deserve it

www.fighterjocks.net (http://www.fighterjocks.net) home of the 11 time Champions Team AFJ. 6 Years Flying http://www.world-data-systems.com/aerofiles/albums/userpics/p47-22.jpg 47|FC=

XyZspineZyX
09-02-2003, 06:33 PM
RedDeth wrote:
- Huckbein FWs quote ....." P-47 had a bad power to
- weight at low altitudes and better than most at
- altitude - for this reason P-47 was outdived at low
- altitude and outdived most at high altitude"..... ok
- huckleberrybein gets the award.... please frame
- this in your trailer in your park huckbein....
- "STUPIDEST POST OF THE MONTH AWARD" congrats you
- deserve it


Oh thanks, and I think you deserve the ban. I'll ask mods to see how it can be arranged fast.


<center> http://www.stormbirds.com/images/discussion-main.jpg </center>

Message Edited on 09/02/0312:50PM by Huckebein_FW

ZG77_Nagual
09-02-2003, 06:50 PM
I gotta say , I like strong, well documented opinions. Doesn't matter if I agree or disagree.
Sure, there's a little America bashing - so what? If it didn't get bashed it wouldn't be America - we'd just go out and crush all oposition while gobbling up resources to buy summer homes for the fat cats running the show...er... uh...like..er... some other...uh ..BAD country.

Anyway - We did build some great planes during WW2 - the Brewster Buffalo - p-39, p63, p38, hellcat, corsair. They're just not the ones everybody thinks are great.


PS - I still think the 109s had some serious problems - but great pilots. Had a great flight last night by the way - against a Blitzpig who really knew his way around the 109g2 - one of those 'no margin' knife fights vs me in the p39 - only lasted a bit over two minutes but whew!

http://pws.chartermi.net/~cmorey/pics/p47janes.jpg

XyZspineZyX
09-02-2003, 07:24 PM
Huckebein_FW wrote:

-
-
- Oh thanks, and I think you deserve the ban. I'll ask
- mods to see how it can be arranged fast.
-
-

You sound more and more like Issy every day./i/smilies/16x16_smiley-very-happy.gif /i/smilies/16x16_smiley-very-happy.gif

http://www.stenbergaa.com/stenberg/taylor-greycap2.jpg


"Only a dead 'chamber pot' is a good 'chamber pot'!"

XyZspineZyX
09-02-2003, 08:09 PM
MiloMorai wrote:
-
- Huckebein_FW wrote:
-
-
--
--
-- Oh thanks, and I think you deserve the ban. I'll ask
-- mods to see how it can be arranged fast.
--
--
-
- You sound more and more like Issy every day


100% troll post. I wonder what is its purpose here.


<center> http://www.stormbirds.com/images/discussion-main.jpg </center>

XyZspineZyX
09-02-2003, 08:31 PM
The only difference you said 'ask' while Issy says 'will'. re. banning./i/smilies/16x16_smiley-wink.gif

I must say I was quite surprised with the civility of some of your later posts in the He177 thread.

http://www.stenbergaa.com/stenberg/taylor-greycap2.jpg


"Only a dead 'chamber pot' is a good 'chamber pot'!"

XyZspineZyX
09-02-2003, 08:52 PM
Huckebein_FW wrote:
- Acceleration in dive or zoom climb is
-
- acc = (T-D)/m - sin(angle)*g
-

Thanks Huckebein, that's more succint and probably
more accurate than the way I put it. I think there
were some errors in my logic previously. But we are
getting there, I think/hope.

An interesting point is that for two planes
with the same thrust to mass ratio diving at
the same angle then T/m and sing(angle)*g are
the same.

T/m isn't the same for the P47 and 109, but for
sake of argument, let's pretend that they are for
a moment, but assume that the total drag (which
is really D(v) of course) for each plane is the same.

This leaves us with a factor ******ing the acceleration
of D/m in each case. Thus the heavier machine (plane
with higher mass) D/m is smaller, and the more massive
plane should pull ahead, if the plane isn't already
at maximum level speed (as at maximum level speed T=D).

As a side note, surface area: mass will tend to be
lower as mass increases, and total drag is somewhat
proportional to surface area.

- In conclusion, if you have a fighter that has a
- higher max speed or higher critical Mach number but
- it does not have a good level acceleration, make the
- dive at a steeper angle than your opponent.

If you are entering the dive at max speed, then T=D
at that point, so dive angle should be the driving
factor for each plane. So if you had a 109 and P47 at
low altitude, at max speed, T=D for both of them, and
dive angle would be the most important factor.

If D(v) increases less quickly for one of the planes, then
we would see that plane win out. I suspect that with a
relatively low Cd, but same D at about 350mph and at
sea level, the P47's drag would probably increase more
slowly as a function of velocity than that of the 109,
and so the P47 would win out.

If the planes aren't at maximum level velocity then
the plane with better power loading will indeed, as others
said (and now makes sense to me, finally) will win out
initially, and maybe indefinitely, depending on how
their drag increases with velocity (and also how well
their airscrew couples at higher speed, and so on).

But the sin(angle)*g term is going to reach parity
with engine thrust for most planes when the dive
angle is over around 15 to 30 degrees, depending on
plane type.

I think there were a lot of us with part of the answer.
Maybe this is the final answer. Maybe it isn't! I might
be completely wrong!

XyZspineZyX
09-02-2003, 09:09 PM
- RedDeth wrote:
-- Huckbein FWs quote ....." P-47 had a bad power to
-- weight at low altitudes and better than most at
-- altitude - for this reason P-47 was outdived at low
-- altitude and outdived most at high altitude"..... ok
-- huckleberrybein gets the award.... please frame
-- this in your trailer in your park huckbein....
-- "STUPIDEST POST OF THE MONTH AWARD" congrats you
-- deserve it

Actually there does seem to be validity in his remarks,
having looked at the equations, at least for initial
acceleration in a dive, and assuming equal dive angle.

Equally my gut feeling that a more massive plane
should do better was somewhat incorrect, except in
the case where the powerloading is equal.

In a vacuum, of course, two objects of any mass
fall at the same rate. It was Gallileo who first
sought to dispel the myth that heavy objects accelerate
more in a fall, although there is debate over whether
he actually did the experiment. The thing is that in
an atmosphere, Gallileo was actually wrong. He used
balls, and the surface area (and thus drag) on the
ball increases with r^2, but the mass with r^3, so
the D/m term is proportional (roughly) to 1/r, so
in face large heavy balls DO accelerate faster when
falling! It is just that for the size of balls he
used g dominates.

So my gut feeling in this case wasn't totally embarassing
due to the prescence of an atmosphere, but I was getting
close to making a total embarassment of myself, physics
degree or not!

Anyway, hopefully it's more sorted out now. There
are lots of niceties over how drag varies with velocity,
airscrew and engine efficiency and the ability to produce
thrust during acceleration in the dive, and so on, though!

XyZspineZyX
09-03-2003, 12:32 AM
AaronGT wrote:

- Er... it is what resists the thrust from the engines
- and stops it going any faster. It is totally
- relevant!

You have to look at the context in which that assertion is offered. My point is this: simply saying one plane has more drag than another means very little.



- Yes, _aerodynamic properties_ but the total drag,
- which also depends on the wetted area is somewhat
- more relevant for determinations of things like
- maximum attainable speeds, since the total drag
- is the force that resists the thrust.

" _aerodynamic properties_", that's what I am talking about.



- I think you mean less, but I think that was just
- a typo!

Yes, a typo.



- The drag coefficient is a pretty approximate way
- of measuring the aerodynamic properties of an
- aircraft.

Exactly what I said.



- Lots of the equations used to determine
- aerodynamic behaviour are also any good for laminar
- flows, and at higher speeds you can get detachment
- of eddies, and all sorts of other non linear
- effects.
- After all, if Cd was all there was too it, there
- would
- be no need for windtunnels, or 512 node beowulf
- systems
- for doing computational fluid dynamics calculations
- for the aero industry.


Agreed.



Regards,

SkyChimp

http://members.cox.net/rowlandparks/corsairs.jpg

XyZspineZyX
09-03-2003, 01:26 AM
AaronGT wrote:

- It shows how much drag there is on the airframe. It
- is
- a very important factor. I don't know why you don't
- understand this.

Again, take my comment in the context that it is offered. I'm quite aware what drag is, why it's important, and how it affects and aircraft.

To simply say one plane has higher drag than another really dives no insight into the aerodynamic efficiency of the aircraft (which was the point I was trying to make). Total drag is a function of many other measurements that does give that insight.



- The Cd of the 109 is higher than the P47, but its
- total drag is lower.

The Bf-109 has less drag than the P-47, but a higher Cd.

Apparently, we agree on this.



- On the whole, as long as the delta v
- is relatively small, such that the Cd for each plane
- remains relatively constant throughout the speed
- increase. The smaller, less aerodynamic aircraft,
- with
- a lower total drag will have a lower force resisting
- its movement, as well as lower inertia.


As long as delta v remains low, such as in level flight. But the speed at which Cd begins to rise dramatically is easily reached in even a short dive.

For instance...

...the Cd of the P-51D was .018 at mach .1 remaining virtually constant to mach .6. At Mach .7 it had risen to .022 (+.004), and at mach .8 it was over .03 (+.012). At mach .85, the near terminal mach of the P-51D, the Cd has risen to .045 (+.027)

Compare that to the Cd of the P-39N, with was .0217 at mach .1, rising ever slighty to mach .6, increasing to .0275 (+.0058) at mach .7, and was .05 (+.0283) at mach .8.

Compared on a curve, the Cd curve for the P-51 remains flatter, longer, and rises at a lesser rate, than it does for the P-39N.

Generally, with very few exceptions, a plane with a lower initial Cd will experience a significant increase in Cd at a higher speed and at a slower rate than one with a higher initial Cd.




- Basically we have F=ma, where F=T-D (thrust - drag).
- or T-CdA=ma. So if the total drag CdA is lower, the
- thrust is the same, and the mass of a smaller plane
- lower then a=(T-CdA)/m would be higher.

I'll have chicken chow mein.



- But what Blitz Pig said isn't about its efficiency,
- just the amount of drag relative to the power put
- into the system. The relative efficiency of the
- design isn't particularly relevant at sea level,
- straight and level, at a steady state.

This is what I said in the post just prior to DDT's comment:

Another thing most people tend
to forget is that Cd rises as speed
increases. Most planes will start to
experience a significant increase at Mach
.6 with the Cd rising dramatically at .8.

Mach .6 is not very fast for a WWII fighter
in a dive. Contemporary WWII fighters with lower
Cds will general maintain their rates of
acceleration in a dive better than those fighters
with higher Cds.

This is the context in which I offered my assertion. I was speaking of dives, and assumed that DDT was offering his comment in that same vein. Later, you say I am correct to concern myself with this.



I completely agree that despite the fact that Bf-109 is less aerodynamically efficient than the P-47, it will accelerate better under ideal circumstances at normal level flight speeds.

But in a dive where speeds exceed mach .6, the rise in Cd will catch up with the Bf-109 sooner, creating insurmountable drag, and at a faster rate, than it will on the P-47.

Ultimately, the P-47 will dive to a high terminal mach than will the Bf-109. This can be seen in tests: the Bf-109F's terminal mach being .805, the P-47's being mach .86.



Regards,

SkyChimp

http://members.cox.net/rowlandparks/corsairs.jpg

XyZspineZyX
09-03-2003, 01:36 AM
Vo101_Isegrim wrote:

- Which brings us to that most NACA-inspired Cd values
- are relative to wing area only, which alone makes Cd
- - or aerodynamic quality - comparisons incompatible.
- Simply because the amount and percentage of the
- total drag created by the wings is very different on
- different designs, ie. a P-51`s wings may be
- responsible for 15% of the total drag, whears on a,
- say Spitfire, with very similiar wing area it can be
- as much as 30%. Yet, you compare ALL DRAG vs. only a
- selected area which doesn`t share the same
- "responsibility" for it on different designs.
-
- This being said, you are already comparing
- incompatible things, and the whole comparision
- doesn`t makes much sense, unless you are comparing
- two planes that are exactly the same, EXPECT for
- their wings.
-
- In fact, the SCIENTIFIC, internationally accepted
- way of measuring aerodynamic shape is always related
- to the frontal surface of the object relative to
- it`s equivalent flat plate drag area.


I agree with this. Comparisons are valid between planes so long as the Cd0 is computated in the same manner for both planes. Using the wing area seems to be universally accepted, though its less telling than when based on the entire wetted area of aircrafts. The difficulty lies in determining the wetted area of an aircraft. Using wing area is much easier. But otherwise, I agree with you.

"The zero-lift drag coefficient, although useful as a measure of comparative aerodynamic refinement, has a basic limitation because the coefficient is based on wing area, and, for a given wing area, many different fuselage and tail sizes may be employed. Thus, differences in zerolift drag coefficients may be interpreted as a difference in aerodynamic refinement when the difference may result from a significant difference in the ratio of wetted area to wing area."





Regards,

SkyChimp

http://members.cox.net/rowlandparks/corsairs.jpg

XyZspineZyX
09-03-2003, 03:00 AM
Top diving A/C of WW2?

Not a soul has mentioned the P-51.

XyZspineZyX
09-03-2003, 03:09 AM
Skychimp, dives at over 0.7 Mach in a ww2 fighter (early war ones at even lower Mach number) are most likely unrecoverable.
Late war fighters Cd is aprox constant up to 0.65 Mach then rises suddenly after. Here the compressibility effects renders the controls ineffective. NACA tried to figure out for years the causes of P-47 diving accidents. Only very well trained pilots who dive according to a plan and are in a shallow dive when passing the 0.65 Mach limit will pull out of dive. Otherways such extreme dives in combat conditions are fatal. You seem to confuse the dive limits in test flights with those in combat situations (this is true for all late war fighters, not only for P-47).


<center> http://www.stormbirds.com/images/discussion-main.jpg </center>

XyZspineZyX
09-03-2003, 03:10 AM
Slickun wrote:
- Top diving A/C of WW2?
-
- Not a soul has mentioned the P-51.

Piston fighter yes, all ww2 fighters Me-262.


<center> http://www.stormbirds.com/images/discussion-main.jpg </center>

XyZspineZyX
09-03-2003, 03:11 AM
Slickun wrote:
- Top diving A/C of WW2?
-
- Not a soul has mentioned the P-51.


I don't think it was. AFAIK, the terminal mach of the P-51D was around .84 to .85. Admittedly those numbers are from anecdotal accounts. But the P-47C-1-RE was dived to mach .86. That's the highest confirmed result I've seen for a WWII prop fighter.

I've seen mach .89 all the way up to mach .92 claimed for various marks of the Spitfire, but I have serious reservations about those numbers, and I've never seen anything, other than anecdotal evidence, to support them.




Regards,

SkyChimp

http://members.cox.net/rowlandparks/corsairs.jpg

XyZspineZyX
09-03-2003, 03:16 AM
By the way I did some dive testing on P-47D-27 and K4 (loaded weights).
Dives from 1500m, starting the dive at 400km/h, two for each aircraft, one at 30 degrees angle the other at 60 degrees, dive until splash into the sea. Here are the results:


K4 / 30deg / 9sec until 600km/h / 17sec until 735km/h
K4 / 60deg / 8sec until 600km/h / 13sec until 735km/h
D27/ 30deg / 10sec until 600km/h/ 18sec until 720km/h
D27/ 60deg / 9sec until 600km/h / 13sec until 720km/h


This results matches perfectly my estimations for 30 degrees (I still have to do the calculations for 60 degrees).




<center> http://www.stormbirds.com/images/discussion-main.jpg </center>

XyZspineZyX
09-03-2003, 03:26 AM
Huckebein_FW wrote:
- Skychimp, dives at over 0.7 Mach in a ww2 fighter
- (early war ones at even lower Mach number) are most
- likely unrecoverable.

What?

They are not. Not even Isegrim will support that. And there is plenty of evidence to prove your statement incorrect.



- Late war fighters Cd is aprox constant up to 0.65
- Mach then rises suddenly after.

That's what I said.



- Here the
- compressibility effects renders the controls
- ineffective.

Not ineffective, LESS effective. But the effects of compressibility were not even severe on most late WWII fighters at mach .65. On the P-51D, the effects of compressibility were not even noticable until mach .74 or .75, even higher on the B/C model.



- NACA tried to figure out for years the
- causes of P-47 diving accidents. Only very well
- trained pilots who dive according to a plan and are
- in a shallow dive when passing the 0.65 Mach limit
- will pull out of dive.

I'm not sure why you think this. Mach .65 (or.70) is not that fast. For instance, the P-47 had a dive speed limit of 500 mph IAS at 12,000 feet. This corresponds to a TAS of 601 mph (mach .82). The plane was routinely dived, in combat, in excess of 500 mph IAS(tons of anecdotal evidence to support this). 500 mph IAS at sea level is mach .65.

Granted, at .82 the effects of compressibility have started, but not to the extent that the plane can not be recovered.


- Otherways such extreme dives
- in combat conditions are fatal.

No, they are not.



- You seem to confuse
- the dive limits in test flights with those in combat
- situations (this is true for all late war fighters,
- not only for P-47).

I think you are the one confused. I think you are confusing dive speed limits and terminal dive speeds. They are not the same thing. A little more research may clear this up. And if Isegrim is the only one you will believe, I'm sure he will explain it to you.


Regards,

SkyChimp

http://members.cox.net/rowlandparks/corsairs.jpg


Message Edited on 09/03/0306:37AM by SkyChimp

XyZspineZyX
09-03-2003, 04:01 AM
Skychimp wrote:

I don't think it was. AFAIK, the terminal mach of the P-51D was around .84 to .85. Admittedly those numbers are from anecdotal accounts. But the P-47C-1-RE was dived to mach .86. That's the highest confirmed result I've seen for a WWII prop fighter.

I've seen mach .89 all the way up to mach .92 claimed for various marks of the Spitfire, but I have serious reservations about those numbers, and I've never seen anything, other than anecdotal evidence, to support them.



Regards,

SkyChimp


Where did you see these confirmed results? We both have the same book, America's 100,000. That volume makes it pretty clear that the P-51 was on a par with the P-47. Anecdotal? You've read the same passages I have. The thing reached 605 mph or mach .83. The Mustang apparently did not go into compressibility until at very high mach numbers compared to other WW2 fighters.

The P-51 apparently accelerated slightly better in the initial dive, then stayed controllable at higher machs. If the P-47 had a slightly higher ultimate diving speed, howling down in an uncontrollable dive, controls locked, a few mph faster than the Mustang, still controllable, so be it, I guess. I'm not convinced of that yet. :-)

If we're talking about "best dive" I think the Mustang is a contender.

XyZspineZyX
09-03-2003, 04:21 AM
Slickun wrote:

- Where did you see these confirmed results? We both
- have the same book, America's 100,000. That volume
- makes it pretty clear that the P-51 was on a par
- with the P-47. Anecdotal? You've read the same
- passages I have. The thing reached 605 mph or mach
- .83. The Mustang apparently did not go into
- compressibility until at very high mach numbers
- compared to other WW2 fighters.
-
- The P-51 apparently accelerated slightly better in
- the initial dive, then stayed controllable at higher
- machs. If the P-47 had a slightly higher ultimate
- diving speed, howling down in an uncontrollable
- dive, controls locked, a few mph faster than the
- Mustang, still controllable, so be it, I guess. I'm
- not convinced of that yet. :-)
-
- If we're talking about "best dive" I think the
- Mustang is a contender.


AHT doesn't talk about TERMINAL mach, it talks about high speed dive tests. The P-51D test referenced doesn't say the plane reached its terminal mach, just that the pilot explored no further. Could it have gone faster? Probably. But who knows how much further.


A USAAF test pilot, however, did push the P-47C-1RE to mach .86 in a July 1943 test at Wright Field.

http://members.cox.net/rowlandparks/MT.jpg



Understand, I am talking in terms of terminal mach, not critical mach.



Regards,

SkyChimp

http://members.cox.net/rowlandparks/corsairs.jpg

XyZspineZyX
09-03-2003, 04:25 AM
BTW, NACA and Republic dive tests summarized in the book "P-47 Thunderbolt: From Seversky To Victory" by Warren Bodie indicate that while elevator forces of the P-47 became heavy in excess of mach .80, even at mach .84 they were very manageable once enough altitude had been shed and the plane entered thicker air.

Regards,

SkyChimp

http://members.cox.net/rowlandparks/corsairs.jpg

XyZspineZyX
09-03-2003, 05:12 AM
JG5_JaRa wrote:
- by the way,
-
- WWMaxGunz wrote:
-- And here you are wrong.
--
-- =================================================
-- (thrust - drag + mass x G) / mass
--
-- does not equal
--
-- (thrust - drag) / mass + (mass x G) / mass
-- =================================================
-
- You're not serious about this, right?
-

I guess I was thinking of something else, not the math and the whole thing just looked wrong. They are equal.

At terminal velocity where the plane is not changing instant velocity.

(thrust - drag) / mass + G = 0

As you say, drag is more than thrust. The more mass, the less the effect of drag.

Something you didn't account for is that as speed increases past medium speeds for a prop plane so does thrust efficiency drop. Once past level max speed the effect of the prop does not vanish, thrust still keeps diminishing and (thrust - drag) becomes a larger negative value even though the prop is still adding some thrust and not become a braking force in itself. Less is less. Power to weight becomes less and less of a factor when prop efficiency is introduced and taken into full consideration? Thrust decreases but mass does not.

I really do wonder if the thrust curves in IL2/FB go beyond level maximum speed? Perhaps that was one thing corrected between 1.0 and 1.1b?

In a dive to less than full level speed (+ some very small amount) then extra mass has no advantage. Does this describe a fighter trying to outdive another? Not for long. Who will win depends more on start conditions and how far the dive is, doesn't it?

I guess that over the USSR in WWII there were less times when a long steep dive was possible? But if that was true then why the accounts of the Finns diving to escape? Ah, but that was before the Yak 3!


Neal

XyZspineZyX
09-03-2003, 05:30 AM
SkyChimp wrote:
- BTW, NACA and Republic dive tests summarized in the
- book "P-47 Thunderbolt: From Seversky To Victory" by
- Warren Bodie indicate that while elevator forces of
- the P-47 became heavy in excess of mach .80, even at
- mach .84 they were very manageable once enough
- altitude had been shed and the plane entered thicker
- air.


No, R. Gilruth the man in charge in NACA with handling requirements for american fighters, and who supervised the NACA investigations about P-47 diving accidents, said that controls heaviness was caused simply by aerodynamic pressure not by compressibility, compressibility caused only controls ineffectiveness.

Also such extreme dives were executed according a careful plan: enter the dive at altitude m and speed x, pull out of dive at altitude n and speed y. There was no room for improvisations. There is absolutely no doubt that such extreme dives could not be performed in combat conditions.





<center> http://www.stormbirds.com/images/discussion-main.jpg </center>

XyZspineZyX
09-03-2003, 06:17 AM
Yawn,

I like the 109G6/AS but hey each to their own.

XyZspineZyX
09-03-2003, 10:12 AM
WWMaxGunz wrote:
- Something you didn't account for is that as speed
- increases past medium speeds for a prop plane so
- does thrust efficiency drop. Once past level max
- speed the effect of the prop does not vanish, thrust
- still keeps diminishing and (thrust - drag) becomes
- a larger negative value even though the prop is
- still adding some thrust and not become a braking
- force in itself. Less is less. Power to weight
- becomes less and less of a factor when prop
- efficiency is introduced and taken into full
- consideration? Thrust decreases but mass does not.

Yes, thrust decreases alone from the fact that engine power stays constant - otherwise, since the power gain of the aircraft is Power = Thrust * TAS, at constant thrust the engine would produce more power at high speed. Other effect like supersonic drag at the propeller tips at high speed add to this thrust decrease.

- I really do wonder if the thrust curves in IL2/FB go
- beyond level maximum speed? Perhaps that was one
- thing corrected between 1.0 and 1.1b?

I think FB uses a convenient extrapolation to high speed without taking particular high speed effects into account, simply because such data are probably not available for most aircraft in the game.

- In a dive to less than full level speed (+ some very
- small amount) then extra mass has no advantage.
- Does this describe a fighter trying to outdive
- another? Not for long. Who will win depends more
- on start conditions and how far the dive is, doesn't
- it?

True, mass is of course not the only factor in a dive. I only discussed the effect of different masses alone, assuming everything else equal. If both aircraft reach their respective Thrust = Drag points quickly, then initial acceleration (slow speed) is not as important as high speed acceleration. Whether or not this is the case depends on the planeset. Estimating this from the little available data alone is difficult since for high speeds, the usual quadratic speed-dependence of drag using drag coefficients as a parameter generally becomes invalid due to rather complex high speed drag properties of the airframe.

- I guess that over the USSR in WWII there were less
- times when a long steep dive was possible? But if
- that was true then why the accounts of the Finns
- diving to escape? Ah, but that was before the Yak
- 3!

I think especially later in the war, when dogfights went to higher altitude, such dives were more common. But dive acceleration was not the only important factor. High speed controllability, which for example was good in the 190, may also have been a reason for such recommendations. Maybe - this is now pure speculation - in the early war, dives to high speed were recommended because of the sometimes poor quality of russian aircraft of that time, remember parts of the skin or even wings detaching already at rather moderate speeds in case of poorly produced LaGGs. Maybe many russian pilots tried to avoid very high speed because of such reasons, not to mention the accounts of russian aircraft flying with open cockpits.
Still, I don't think trying to outdive a Yak 3 at low speed and low alt is a good idea, not only because of the negative effects of low altitude on dive performance.

XyZspineZyX
09-03-2003, 10:15 AM
Tempest dive, AIR 64/32.



http://hometown.aol.co.uk/JStirlingBomber/Temp+dive+1.jpg

XyZspineZyX
09-03-2003, 10:22 AM
R.A.E Farnborough, Drag and trim changes on Spitfire,Mustang and Thunderbolt in flight at high Mach numbers. report no. Aero 1906. DSIR23/13261

http://hometown.aol.co.uk/JStirlingBomber/Spit+drag+1.jpg

XyZspineZyX
09-03-2003, 10:30 AM
SkyChimp wrote:
- I completely agree that despite the fact that Bf-109
- is less aerodynamically efficient than the P-47, it
- will accelerate better under ideal circumstances at
- normal level flight speeds.

after doing some more reading I am inclined to agree
with you.

If we have the same total drag and power loading,
even then the D/m term is lower for a more massive
plane, and even that particular term is going to
be in the P47's favour at maximum level speed.

I was going to do some calculations based on the
relative mass and power of the 109 and P47, but
it became quickly apparent that without figures
on the level acceleration of the planes near
the maximum speed I can't calculate the prop
efficiency near the maximum level speed.

otherwise if I assume a maximum level speed of
about 360mph (i.e 160 m/s - handy to work with),
and a 1850hp engine in a 3600kg 109, then
kxPower=Thrust.speed, or 1850x746=160.F,
1850x746=160.3600.a and we'd get a 2.4g acceleration
from a 109! [Edit: oops - slip with the decimal point -
should have been 0.24g - about right??]

If I can get some level acceleration figures then
I can do some slightly improved back-of-envelope
calculations with correct values of k. Then I can
calculate a little table of initial dive accelerations
for the P47D25 and 109G10 from their maximum level speeds
at sea level, at least.





Message Edited on 09/03/0310:15AM by AaronGT

XyZspineZyX
09-03-2003, 10:39 AM
Huckebein_FW wrote:
- Slickun wrote:
-- Top diving A/C of WW2?
--
-- Not a soul has mentioned the P-51.
-
- Piston fighter yes, all ww2 fighters Me-262.

I remember a comment from the AFDU saying that
they felt the Tempest V was about the best plane
in a dive that they had tested. In the oft quoted
tactical trials, a dive test against the P51B
is about the only thing not tried, however.

XyZspineZyX
09-03-2003, 10:45 AM
Ah - nice to see that the Tempest V might be
king of the dive! Yay for the UK for once.
We may be crap at making baloons now, but we could
make decent planes 60 years ago :-)

XyZspineZyX
09-03-2003, 10:58 AM
AronGT wrote.

"In the oft quoted
tactical trials, a dive test against the P51B
is about the only thing not tried, however."

Mustang a documentary History by Jeffery Ethell contains part of the report as it pertains to the P51B Vrs the Tempest V.

Page 60. Dive.
The Tempest tends to pull away.

Also.

http://hometown.aol.co.uk/JStirlingBomber/Temp+dive+2.jpg


http://hometown.aol.co.uk/JStirlingBomber/Temp+dive+4a.jpg

XyZspineZyX
09-03-2003, 11:53 AM
hmm all this talk of diving yet no one talks of the spitfire XI diving tests after the war, where marcelle reached sumwhere between mark .89 - .91 losing his prop and taking some injuries.

http://ubbxforums.ubi.com/infopop/emoticons/icon_smile.gif

http://lamppost.mine.nu/ahclan/files/sigs/spitwhiners1.jpg

XyZspineZyX
09-03-2003, 01:00 PM
LOL, it seems the *Spitfire, the highest diving Mach reaching aircraft of WW2* hype is here again, and in full-scale attack against sanity. /i/smilies/16x16_smiley-very-happy.gif

Just some notes, regarding the hype:

All the 0,89 and above Mach and co. hypes started with a single accident, when a British pilot went into a dive with a Spit, lost conciousness, and when recovered found himself in a climb.

Now, the Brits managed somehow to conlclude from this that he had reached .89 Mach or so, and, probably to boost morale (at the time many Spits lost wings in dives), improvised a series of *tests* to prove it. Like the one excerpt posted by Neil. The results of test were various, typically they ended the plane breaking up in a dive, shearing off its main propellor gearing, loosing the whole propellor etc. Most important of all, they never did any position error correction to the IAS reading from the pitot tube, simply converting or estimating the air speed, and then converting it to TAS... This is supposed to be comparable to other tests where the planes did not broke up, remained fully controllable, and speeds were measured in more scientific manner...

I also find it interesting that Neil comes up with that article for God-knows how many times now, when frankly, the *results* (more like: beliefs of the author) are closer to the term of a joke. These dive test results on the other hand are conflict with the tests at ADFU, where they tested the worst captured planes agaisnt their best... in particular, the articles dive graph claims that the Spit IX and XVI (the latter being practically the same) outdives both the FW 190A and Me 109G.

However, in the actual trials (which were, and this should be noted vs. an early FW 190A-3 and a Me 109G-6 with gunpods, neither running at their full boost), the Brits got the following results:

***
Spitfire IX vs. FW 190A:

Dive: The FW 190 is faster than the Spitfire IX in a dive, particularly during the initial stage. This superiority is not as marked as with the Spitfire VB.
***

Spitfire IXLF vs. Me 109G:

***
Dive
19.........Comparitive dives between the two aircraft have shown that the Me.109 can leave the Spitfire without any difficulty.
***

Interesting, isnt it? In Neils article, it all turned to be the exact opposite: on that piece of paper, Spits outdive both 109s and 190s, and 190s also manage to outdive 109s, which also conflicts with the results of all German tests !


Now back on the Spit diving hype: good diving properties require a number of qualities. Like:

Preferably high weight
High wingloading
High powerloading
Low-drag design
Thin airfoil
Stiff wings

Now does the Spit have these qualities? No. It has moderate weight, very low wingloading, avarage powerloading, absolutely not stiff wings, STRAIGHT!!! leading edge, and worst of all, its an old airframe with some very bad ideas regarding aerodynamics (huge bag-like radiators, cannons stubs in front of leading edge, bad nose shape, non-retracting tailwheel, non-faired u/c etc.) with a huge drag as a result, the engine and propellor run at very high RPM, resulting that the propellor tips constantly run at near-Mach speeds, de facto acting as an airbrake, the plane has poor longitudal stability at high speeds (nose oscillating movements)...

Sorry, but knowing all this, I can only laugh my *ss out when this joke about the ,89 Mach (not to mention in its improved for of 0,9+ MAch) comes up again and again...

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'Only a dead Indianer is a good Indianer!'

Vezérünk a Bátorság, K*sérµnk a Szerencse!
(Courage leads, Luck escorts us! - Historical motto of the 101st Puma Fighter Regiment)

Flight tests and other aviation performance data: http://www.pbase.com/isegrim

XyZspineZyX
09-03-2003, 06:36 PM
SkyChimp wrote:
- To simply say one plane has higher drag than another
- really dives no insight into the aerodynamic
- efficiency of the aircraft (which was the point I
- was trying to make). Total drag is a function of
- many other measurements that does give that insight.
-
?really?
-
-- The Cd of the 109 is higher than the P47, but its
-- total drag is lower.
-
- The Bf-109 has less drag than the P-47, but a higher
- Cd.
-
Aha the drag force as a function of velocity is lower than for P-47...good. It's as easy to say Bf has less drag and less wing whichever sounds more pleasant. Bf has less drag but smaller tires, hmmm... Bf has less drag but ugly camouflage job.

-- On the whole, as long as the delta v
-- is relatively small, such that the Cd for each plane
-- remains relatively constant throughout the speed
-- increase. The smaller, less aerodynamic aircraft,
-- with
-- a lower total drag will have a lower force resisting
-- its movement, as well as lower inertia.
-
relatively small? it can change as much as it wants before Mach divergence number.

- As long as delta v remains low, such as in level
- flight. But the speed at which Cd begins to rise
- dramatically is easily reached in even a short dive.
-
Easily? It will take more like 1500 m from 3000 m for P-47
to reach 700 km/h (Ma=0.6) starting from 400 km/h. At this speed it's still below drag divergence for sure. Oh, continue a bit longer maybe advantage is showing, at ground level it will be seen P-47 digs faster than Bf.

- Compared on a curve, the Cd curve for the P-51
- remains flatter, longer, and rises at a lesser rate,
- than it does for the P-39N.
-
- Generally, with very few exceptions, a plane with a
- lower initial Cd will experience a significant
- increase in Cd at a higher speed and at a slower
- rate than one with a higher initial Cd.
-
You might have to back up that _generally_ Prandtl-Glauert does not happen to agree with you. You can't also say that this was lower its raise will be slower. If you speak of compressible subsonic area there is no difference (there is raise but it's relatively same), approaching the transonic area you'll be dealing with critical Mach number and drag divergence number. In this area, take two aircraft one with higher Cd but swept wing another one with lower Cd but straight wing. Tell what happens? One has supercritical airfoil the other does not same cd what happens? Generally my a$$


- Another thing most people tend
-
- to forget is that Cd rises as speed
-
- increases. Most planes will start to
-
- experience a significant increase at Mach
-
- .6 with the Cd rising dramatically at .8.
-
-
- Mach .6 is not very fast for a WWII fighter
-
- in a dive. Contemporary WWII fighters with lower
-
- Cds will general maintain their rates of
-
- acceleration in a dive better than those fighters
-
-
- with higher Cds.
-
Increase in pressure coefficient is 25% at Ma=0.6, just as well for P-47 as for Bf-109. Ma=0.6 is not transonic flow. Your figures for P-51 are still within the normal theory and the relative advantage is visible first in Ma=0.8. You're not seriously claiming shock wave formations at Ma=0.6, are you?

You're not expecting a transonic, or compressible subsonic modeling, are you?

- I completely agree that despite the fact that Bf-109
- is less aerodynamically efficient than the P-47, it
- will accelerate better under ideal circumstances at
- normal level flight speeds.
-
Despite better power to weight and despite lower drag force at given speed? Must be a seldom ideal circumstance, existing anywhere below ~8km or so (before P-47 starts showing comparable power to weight). Well, whatever you mean with that efficiency it must be so.

- But in a dive where speeds exceed mach .6, the rise
- in Cd will catch up with the Bf-109 sooner, creating
- insurmountable drag, and at a faster rate, than it
- will on the P-47.
-
Based on what? I'd really love to see you back that one up.
Come on quit creating your own theories some of the children are so sensitive to influence. I am sorry for the irritated tone but I find that mixing facts with wishes and putting unqualified speculation quite irritating. These belong rather to the unwanted category:

"Another notice is that we do not accept the bug reports like "this plane flying bad! I think it should fly better!" without technically documented arguments on enginiring level of knowledge."

From:

http://forums.ubi.com/messages/message_view.asp?name=us_il2sturmovik_gd&id=zbmlw

(enginiring level translates to engineering)

Again you're looking for the advantage in the wrong place and basing your theories on wishes and dreams. Take it up to 10 km and hope that somebody bothers to come up and fight fair and that the advantage starts showing before the end of the sim code capabilities (which was originally created for low alt) kick in. Or pay Maj_Death with hard cash and take "how to survive on the deck" lessons with P-47.

Most of the time you people turn and burn down on the deck waste your speed below 400 km/h and then start legendary P-47 outdives anybody escape. Then you absorb complete ammoload from Yak-3 (enough lead to down 10 B-17), next thing you know login to ORR and b!tch it does not dive correctly, it's not fast and it's not durable.

You should also consider that high power to weight and low wingloading leads to generally flatter curves, (drop in thrust and raise in drag). No aircraft designer in his right minds wants to pack some additional weight to his design. Heavy weight=bad design.




-------------------------------------
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Message Edited on 09/03/0307:10PM by Ugly_Kid

XyZspineZyX
09-03-2003, 06:44 PM
Ugly_Kid wrote:
-
- Most of the time you people turn and burn down on
- the deck waste your speed below 400 km/h and then
- start legendary P-47 outdives anybody escape. Then
- you absorb complete ammoload from Yak-3 (enough lead
- to down 10 B-17), next thing you know login to ORR
- and b!tch it does not dive correctly, it's not fast
- and it's not durable.
-


LOL, so far the best part in this thread. Hundred percent true! /i/smilies/16x16_smiley-happy.gif

'...waste your speed below 400 km/h and then start Legendary P-47 Outdives Anybody Escape'... <--- /i/smilies/16x16_smiley-very-happy.gif /i/smilies/16x16_smiley-very-happy.gif /i/smilies/16x16_smiley-very-happy.gif /i/smilies/16x16_smiley-very-happy.gif /i/smilies/16x16_smiley-very-happy.gif /i/smilies/16x16_smiley-very-happy.gif

http://vo101isegrim.piranho.com/FB-desktopweb.jpg
'Only a dead Indianer is a good Indianer!'

Vezérünk a Bátorság, K*sérµnk a Szerencse!
(Courage leads, Luck escorts us! - Historical motto of the 101st Puma Fighter Regiment)

Flight tests and other aviation performance data: http://www.pbase.com/isegrim

XyZspineZyX
09-03-2003, 06:57 PM
And Huck was somewhat correct concerning the dive angles. The Mach effects are more an issue for higher altitude (lower speed of sound) as for the lower alt. For this reason diving from a higher altitude may initially bring you to near transonic speeds and cause problems with compression. The next thing you know is that while loosing altitude speed of sound increases and somewhere at low alt you will be back in lower Mach number and regain control. What do you do then if you blast to 2000 m with 800 km/h and regain controllability? If you dive 90? you dig a hole, if your angle is 45? you might just recover...

-------------------------------------
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XyZspineZyX
09-03-2003, 07:15 PM
Vo101_Isegrim wrote:
- LOL, so far the best part in this thread. Hundred
- percent true!

Coming from the dark master I am terribly honoured /i/smilies/16x16_smiley-very-happy.gif

P.S How do you write Ӟk¤z¤k¤tr¤ or the word you use while drinking?


-------------------------------------
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XyZspineZyX
09-03-2003, 07:57 PM
Calculated accelerations in 30 deg dive:

http://home.comcast.net/~bogdandone/30degdive.JPG



250mph ~ 400km/h / K4: 22.6ft/sec^2 / D27: 19.7ft/sec^2
375mph ~ 600km/h / K4: 16.4ft/sec^2 / D27: 15.3ft/sec^2
450mph ~ 720km/h / D27: 12.3ft/sec^2
460mph ~ 735km/h / K4: 12ft/sec^2

because acceleration decreases almost linearly at those speeds we can calculate a medium acceleration:

250 to 375mph / K4: 19.5ft/sec^2 / D27: 17.5ft/sec^2
250 to 450mph / D27: 16ft/sec^2
250 to 460mph / K4: 17.3ft/sec^2

time to accelerate from speed x to y: y = x + at, a = acceleration, t = time

400 to 600km/h

K4: t = ((600-400)/3.6)/(19.5/3.28) = 55.6 / 5.9 = 9.4sec, same result as in FB
D27: t = ((600-400)/3.6)/(17.5/3.28) = 55.6 / 5.3 = 10.5sec, same result as in FB

400 to 720km/h

D27: t = ((720-400)/3.6)/(16/3.28) = 88.9 / 4.9 = 18.1sec, same result as in FB

400 to 735km/h

K4: t = ((735-400)/3.6)/(17.3/3.28) = 93.1 / 5.3 = 17.6sec, same result as in FB


I also verified for 60 degrees dive, and FM is correct.

Some corrections though:

K4 / 60deg / 6sec until 600km/h / 11sec until 735km/h
D27/ 60deg / 7sec until 600km/h / 11sec until 720km/h

Dive time is shorter with 2 seconds than first measurement, because it takes some time to get from level to 60 degrees dive. It takes a very short time to get into a 30 degrees time dive, but to reach 60 degrees it takes aprox more than 1 sec, affecting the result. So I tried a different dive: from 300km/m and 1500m enter in a 60 degrees dive and measure the time from 400 to 600km/h - it was indeed shorter with 2 seconds. I noticed this error by estimating the results, I obtained 6 sec in K4 from 400 to 600km/h, so I thought that there should be a problem with testing procedure (and indeed it was).

In conclusion dive and zoom climb model in FB is correct, P-47 FM including.



<center> http://www.stormbirds.com/images/discussion-main.jpg </center>

XyZspineZyX
09-03-2003, 08:03 PM
Ugly_Kid wrote:

- Most of the time you people turn and burn down on
- the deck waste your speed below 400 km/h and then
- start legendary P-47 outdives anybody escape.

Where is there to dive when down on the deck? Do you mean maybe up to 1 or 2 km alt? For certain 1km is low. Johnson had a trick of not a terribly long dive but of utilising a dive followed by a zoom climb to gain advantage on a following plane. Exact speeds and angles I don't know but in his mock combat with the Spit he was zoom climbing about when the Spit was into the dive. It would be good to know the full geometry of the move and it appears that outdiving the Spit was not his goal, only catching the other unready after already throwing him off with so many rolls and turns.

The P47 could not outturn the Spit and yet it could start a turn much sooner in any direction. I am sure that this held even more true for the FW190.

- You should also consider that high power to weight
- and low wingloading leads to generally flatter
- curves, (drop in thrust and raise in drag). No
- aircraft designer in his right minds wants to pack
- some additional weight to his design. Heavy
- weight=bad design.

And here I agree in theory totally and yet I have to wonder just what in the world that Seversky could have been thinking? The P47 was as close to an airborne tank as any prop plane I can think of. It wasn't designed as a bomber and it met with good success as a fighter if used with the right tactics. It still was superceeded and yet it doesn't come up as a neccessarily bad design despite being so heavy, big and such a poor power-loading. I can only conclude (is this too strong a word?) to myself that this plane filled a niche very well in the way of fighter tactics and while it wasn't the best it certainly wasn't obsolete even to the end of the war. Which just may show there are limits to generalities in common sense?


But I do heartily agree that many expect it to do far too much. As for it soaking up fire in DF... LOL! I see more reports on this and that plane always doing exactly the same! I chalk most of those up to inability to either count hits or know which hits make a difference. At least that plane was well known to be able to take it although those are just the ones that made it back. I see many posts about how quickly the engine gets killed in the same plane so I wonder where the hits are from that full ammoload of the Yak-3? Somebody is not shooting so well!


Neal

XyZspineZyX
09-03-2003, 09:16 PM
WWMaxGunz wrote:
- Where is there to dive when down on the deck? Do
- you mean maybe up to 1 or 2 km alt? For certain 1km
- is low. Johnson had a trick of not a terribly long
- dive but of utilising a dive followed by a zoom
- climb to gain advantage on a following plane.

That's more or less what I was trying to say. If you're down low on low speed your exit-route is pretty limited. I think below 3 km you don't have to dream on diving away, you will not reach that high velocity. It also has the eventual point where you have to level out. If the opponent follows a more shallow dive he will fly the diagonal course and meet you in the end...(You can calculate how much faster you have to fly the longer way 2/sqrt(2)?) The only trick is to go for a downward spiral that will force your opponent to follow, because he does not know which course you will level out.


-------------------------------------
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XyZspineZyX
09-03-2003, 11:17 PM
Just in case anyone missed it.



http://hometown.aol.co.uk/JStirlingBomber/Spit+drag+1.jpg

XyZspineZyX
09-03-2003, 11:53 PM
Neil - interesting figures. That does seem
to very much support the 0.89 Mach spitfire
test, and given all the additional data after
the point it reached 0.89 does suggest that
the plane didn't fall apart, but landed safely?

I presume that the g readings are in terms of
a g meter in the cockpit, rather than a measure
of how much the plane was increasing its near
suicidal rush towards the earth?

XyZspineZyX
09-04-2003, 12:10 AM
Tests done by NACA showed that WW2 style A/C were unable to go faster than mach .85 or so, no matter what. The propellor was just not efficient enough to do it. At those speeds it acted as a whirling brake disc.

Hi tech engineering was able to produce a prop allowing about .87 to .89 after the war.

I am paraphrasing the article that I have somewhere. I always get a kick out of the claimed .89 and faster Spitfire mach numbers. I guess if the prop fell off, the airframe alone could go past mach .85. ya know, pull in that air brake.

If the Spitfire dove that well, better than any other prop plane in WW2, maybe ever, it is only common sense that it would have been an oft used and much ballyhooed part of the Spitfire package. One finds, however, that the opposite is true. Johnny Johnsons book "Wing Commander" makes no bones that the Spitfire could not compete with the LW planes in a dive, except in special circumstances. The dive was used in the bounce, but if the LW plane split essed, the fight was over.

Every "comparison" test I've ever read, done by the RAF, LW, or USAF, does not expose the Spitfire as a diving behemoth. Nowhere does it say something like, wow, diving is the best part of this package! I must say, the reviews are mediocre at best.

Yet, the reviews of the Tempest, P-47, and yes, the hated Mustang DO paint the picture of an outstanding diving machine, and the tactic was an integral part of those planes' pedigree, and are well documented. The diorama of bounce, split s, hair on fire dive to the deck, and a blazing fast finishing dogfight were repeated over and over with those planes and the LW.

XyZspineZyX
09-04-2003, 12:15 AM
Huckebein_FW wrote:

- No, R. Gilruth the man in charge in NACA with
- handling requirements for american fighters, and who
- supervised the NACA investigations about P-47 diving
- accidents, said that controls heaviness was caused
- simply by aerodynamic pressure not by
- compressibility

The faster a plane flys, the more pressure on the control surfaces. ALL aircraft experience this.

In a dive, the P-47 could fly faster than most, and could achieve very high speeds at high altitudes.

The incidents to which you refer involved P-47B aircraft, which at the time were new to all that flew them. Pilots inadvertently dove too fast, got into severe compressibility, and did not know how to get out.

Pilots later learned that diving to lower altitudes, where air was denser, would return elevator control to them. If speeds were extremely high, pilots could use elevator trim to get out of a dive. As time went by, they found that they needed to be careful not to dive to too high of an airspeed.

But dives up to and over mach .80 were controllable, and common. The P-47 had a dive limit speed of 500 mph IAS for altitudes under 25,000 feet. A preferred and recommneded tactic to evade enemy fighters was to dive until the airspeed indicator showed 500 mph. At 12,000 feet, the recommended pullout, that equated to mach .82.



- compressibility caused only
- controls ineffectiveness.

First, compressibility does many weird and wonderful things to aircraft. Sometimes is causes a decrease in control surface effectiveness. In other cases, it causes aileron over-balance, stick reversals, buffetting and in different manners.



- Also such extreme dives were executed according a
- careful plan: enter the dive at altitude m and speed
- x, pull out of dive at altitude n and speed y. There
- was no room for improvisations. There is absolutely
- no doubt that such extreme dives could not be
- performed in combat conditions.


You said earlier that dives to .70 would be unrecoverable. Is that your definition of "extreme dives", or has it now changed since you realize you were wrong about that.

"Extreme dives" is a relevative, and extremely subjective, term. An extreme dive for a P-47 may be a dive to speeds in excess of mach .82. For the P-47 it may be dives to mach .83 or more. For the Bf-109, it may have been mach .75.

As stated, dives up to mach .82 were common and a recommend evasive tactic for P-47 pilots.

Regards,

SkyChimp

http://members.cox.net/rowlandparks/corsairs.jpg

XyZspineZyX
09-04-2003, 12:36 AM
Ugly_Kid wrote:

- ?really?

Yes.



- Aha the drag force as a function of velocity is
- lower than for P-47...good. It's as easy to say Bf
- has less drag and less wing whichever sounds more
- pleasant. Bf has less drag but smaller tires,
- hmmm... Bf has less drag but ugly camouflage job.

The Bf-109 had a black cross on it, it weighed less than a white star, increasing its power to weight ratio. So, the swastika, as a funtion of drag, was superior to the white star.



- relatively small? it can change as much as it wants
- before Mach divergence number.

I didn't say "relatively small", I said "relatively constant." Or didn't you bother to read before responding?





- Easily? It will take more like 1500 m from 3000 m
- for P-47
- to reach 700 km/h (Ma=0.6) starting from 400 km/h.
- At this speed it's still below drag divergence for
- sure. Oh, continue a bit longer maybe advantage is
- showing, at ground level it will be seen P-47 digs
- faster than Bf.



- You might have to back up that _generally_
- Prandtl-Glauert does not happen to agree with you.
- You can't also say that this was lower its raise
- will be slower. If you speak of compressible
- subsonic area there is no difference (there is raise
- but it's relatively same), approaching the transonic
- area you'll be dealing with critical Mach number and
- drag divergence number. In this area, take two
- aircraft one with higher Cd but swept wing another
- one with lower Cd but straight wing. Tell what
- happens? One has supercritical airfoil the other
- does not same cd what happens? Generally my a$$

I see, your a$$ has been doing the reading. I'm talking about comparable aircraft. I thought that might have been evident to a "scientist."



- Increase in pressure coefficient is 25% at Ma=0.6,
- just as well for P-47 as for Bf-109. Ma=0.6 is not
- transonic flow. Your figures for P-51 are still
- within the normal theory and the relative advantage
- is visible first in Ma=0.8. You're not seriously
- claiming shock wave formations at Ma=0.6, are you?
- You're not expecting a transonic, or compressible
- subsonic modeling, are you?


I'm saying Cd for the P-51 begins to rise noticeably at Mach .6. It rises more dramatically as speed increases with a serious upturn at about mach .7. What's hard for you to understand about that.

If you disagree, please post your theory, and we'll compare it to NACA charts?



- Despite better power to weight and despite lower
- drag force at given speed? Must be a seldom ideal
- circumstance, existing anywhere below ~8km or so
- (before P-47 starts showing comparable power to
- weight). Well, whatever you mean with that
- efficiency it must be so.
-
- Based on what? I'd really love to see you back that
- one up.
- Come on quit creating your own theories some of the
- children are so sensitive to influence. I am sorry
- for the irritated tone but I find that mixing facts
- with wishes and putting unqualified speculation
- quite irritating. These belong rather to the
- unwanted category:

Bu, bu, bu, but, the Bf-109 was faster, under all circumstances, it had to be, it was German, and I have a chart, the black cross thing...

Perhaps you can come up with a better way to explain that the terminal mach of the Bf-109F was mach .085, while that of the P-47C was mach .86. Perhaps you can explain why the Bf-109 entering into compressibility well before the P-47?



- "Another notice is that we do not accept the bug
- reports like "this plane flying bad! I think it
- should fly better!" without technically documented
- arguments on enginiring level of knowledge."

Or arrogant individuals who believe they can calculate a plane into the performance they desire while ignoring its documented performances.

Regards,

SkyChimp

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XyZspineZyX
09-04-2003, 12:39 AM
WWMaxGunz wrote:
-
- Ugly_Kid wrote:
-
-- Most of the time you people turn and burn down on
-- the deck waste your speed below 400 km/h and then
-- start legendary P-47 outdives anybody escape.
-
- Where is there to dive when down on the deck?

That's the moronic argument I see from the P-47 naysayers all the time. "The Fw-190whatever outdived the P-47 at 1000 meters." Yeah, right into the ground in seconds.

Just how did that wonderful Fw-190 compare at realisitic combat altitudes, say 20-30,000 feet. (And we won't even worry about the fact that the Fw-190A was nearly incontrollable at 25,000 feet and over.)



Regards,

SkyChimp

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XyZspineZyX
09-04-2003, 12:47 AM
Ugly_Kid wrote:
- And Huck was somewhat correct concerning the dive
- angles. The Mach effects are more an issue for
- higher altitude (lower speed of sound) as for the
- lower alt. For this reason diving from a higher
- altitude may initially bring you to near transonic
- speeds and cause problems with compression. The next
- thing you know is that while loosing altitude speed
- of sound increases and somewhere at low alt you will
- be back in lower Mach number and regain control.

=======

Wait a minute, Ugly, that sounds familiar. Let's see, I said earlier in this thread:

-- BTW, NACA and Republic dive tests
-- summarized in the book "P-47 Thunderbolt:
-- From Seversky To Victory" by Warren Bodie
-- indicate that while elevator forces of
-- the P-47 became heavy in excess of mach .80,
-- even at mach .84 they were very manageable
-- once enough altitude had been shed and the
-- plane entered thicker air.


Huck's response was:

"No,..."




Regards,

SkyChimp

http://members.cox.net/rowlandparks/corsairs.jpg

XyZspineZyX
09-04-2003, 01:22 AM
"Just how did that wonderful Fw-190 compare at realisitic combat altitudes, say 20-30,000 feet. (And we won't even worry about the fact that the Fw-190A was nearly incontrollable at 25,000 feet and over.)"

Which seems to bring this long discussion to a full circle, in circumstantial factors I have stated. I am suspicious that many of the 'dive' discussions are associated with typical FB MP conditions, rather than the 'realitic altitudes' stated.

The somewhat exaggerated and infuriated /i/smilies/16x16_smiley-wink.gif response from Ugly_Kid, as Isegrim points out, probably holds more truth than actually perceived.

In a recent quick-test I've tried, a 0G powerdive starting from 400km/h at 3000m, the P-47 series reaches deck alts typically 3~5 seconds faster than a Bf109G-6. 3~5 seconds in speeds of over 600km/h amounts up to pretty large distance, but it is a distance which can be shortened as soon as the plane has to level out, if the chasing plane has a max speed limit higher than the P-47 at deck altitudes.

So in games vs reality, it really typically comes down to the chaser, not the chased. If the chaser, unlike in reality, is willing to risk high enemies dropping down on him, going through unpleasant high speed dives, grunting on the handle in a dangerous pull-out attempt.. then he'll catch the P-47 extending away when he reaches deck and has no choice but to level out - and then he will probably get shot down almost immediately after he knocks the P-47, if there are hostile enemy planes nearby.






-----------
Due to pressure from the moderators, the sig returns to..

"It's the machine, not the man." - Materialist, and proud of it!

Message Edited on 09/04/0309:32AM by kweassa

XyZspineZyX
09-04-2003, 01:24 AM
http://members.cox.net/rowlandparks/temp.jpg



I've seen this report before. I'd like to ask some questions:


1) The report says a Thunderbolt II. I thought the Thunderbot IIs in the RAF were bubble top aircraft? I admit I may be wrong on this.

But if I'm right, all bubble-top versions of the P-47 were serially produced with water injection. Why not this one?



2) 58" of mercury? That's roughly indicative of an R-2800-21 engine on the early P-47s. P-47D-20 to D-40 used the R-2800-59 which developed 64" of mercury on 100 octane fuel. Was this a bubble top with its water injection system removed? If so, why?

3) The Tempest II was 80 mph faster up to 5,000 feet.

Let's assume for the moment that the P-47 being compared IS an older -21 engined model. The P-47C-1 was capable of
340 mph on the deck. Was the Tempest II capable of 420 mph on the deck?

At 12,000 feet the Tempest was 70 mph faster. The P-47C-1 could do 385 mph at 12,000 feet: the Tempest II could do 455 mph?

4) The Tempest II was 2,000 fpm better than the Thunderbolt II at sea level. The P-47C-1 could manage just 2,750 fpm at sea level. Did the Tempest II climb at 4,750 fpm at sea level?

At 8,000 feet, the P-47C was climbing at 2,650 fpm. The Tempest II was climbing at 4,150 fpm?



These are some truly amazing numbers for the Tempest II. I'm stunned the RAF felt a need to develope a Tempest V.
(Note: This comment is tongue in cheek to all you RAF plane lovers with no sense of humor or sarcasm.)

More seriously, the performance difference are SO marked that there can only be two explantions:

1) The Tempest II was a stellar performer that performed well in excess of it's published specs.

2) Something is up with that P-47 in the test /i/smilies/16x16_smiley-wink.gif


Either way, the veracity of the test is questionable.





Regards,

SkyChimp

http://members.cox.net/rowlandparks/corsairs.jpg

XyZspineZyX
09-04-2003, 01:31 AM
kweassa wrote:

- The somewhat exaggerated and infuriated /i/smilies/16x16_smiley-wink.gif response from Ugly_Kid, as
- Isegrim points out, probably holds more truth than
- actually perceived.


Perhaps.

If memory serves, I never complained about dive acceleration rates for the P-47, only the dissintigration of the plane at 900 km/h. My issue was roll rate, and I had the documentation to back my assertions.

I agree, low level, shallow angle, dive acceleration will favor the lighter German planes.

I asked Huck last time he posted his chart to post the Fw-190A (and others) dive acceleration from 25,000 and 30,000 feet at various angles. I can provide engine charts for many planes if he cares to do so.

This would give us a more logical and historically significant perspective on dive performance.

Regards,

SkyChimp

http://members.cox.net/rowlandparks/corsairs.jpg

XyZspineZyX
09-04-2003, 01:33 AM
Vo101_Isegrim wrote:

- Sorry, but knowing all this, I can only laugh my *ss
- out when this joke about the ,89 Mach (not to
- mention in its improved for of 0,9+ MAch) comes up
- again and again...


I've read about the "passing out and awaking in a climb" thing, too. I have no idea if that is true or not. Mach .89 is a little hard to swallow. Neil, can you provide details of the test?

Regards,

SkyChimp

http://members.cox.net/rowlandparks/corsairs.jpg

XyZspineZyX
09-04-2003, 01:36 AM
Correction, I said earlier:

- Perhaps you can come up with a better way to explain
- that the terminal mach of the Bf-109F was mach .085,
- while that of the P-47C was mach .86. Perhaps you
- can explain why the Bf-109 entering into
- compressibility well before the P-47?

The Bf-109F's terminal dive speed was .805, not .85.

Stupid forums would allow an edit.

Regards,

SkyChimp

http://members.cox.net/rowlandparks/corsairs.jpg

XyZspineZyX
09-04-2003, 01:54 AM
SC, the Tempest II came after the Tempest V and VI. Due to technical troubles and a lack of engineers the Centaurus that powered the II did not see production till late in the war. About 2800 were built.

http://www.stenbergaa.com/stenberg/taylor-greycap2.jpg


"Only a dead 'chamber pot' is a good 'chamber pot'!"

XyZspineZyX
09-04-2003, 02:03 AM
MiloMorai wrote:
- SC, the Tempest II came after the Tempest V and VI.
- Due to technical troubles and a lack of engineers
- the Centaurus that powered the II did not see
- production till late in the war. About 2800 were
- built.


OK, my error.

Perhaps the Tempest II did perform to those specs? The Tempest II was the version used in the Korean War?

Nevertheless, why compare to the earliest -21 engined P-47 fighter?

Or maybe it was compared to a later P-47. But the 58" of mercury and no water injection is very, very odd. Again, that's not consistent with the best performing P-47s that did see service in WWII. Why not compare it to the M, for instance?

Don't get me wrong, I'm not disparaging my English brothers' plane, I just don't understand the nature of the test, or exactly what was involved.





Regards,

SkyChimp

http://members.cox.net/rowlandparks/corsairs.jpg


Message Edited on 09/04/03 05:04AM by SkyChimp

Message Edited on 09/04/0306:16AM by SkyChimp

XyZspineZyX
09-04-2003, 02:09 AM
SkyChimp wrote:

-
- Perhaps the Tempest II did perform to those specs?
- The Tempest II was the version used in the Korean
- War?
-
-

No, that was the SeaFury.

The last Tempest II sortie was flown 6 June 1951 in Malaysia.
Afaik that is as close to Korea as they got.

http://www.stenbergaa.com/stenberg/taylor-greycap2.jpg


"Only a dead 'chamber pot' is a good 'chamber pot'!"

XyZspineZyX
09-04-2003, 02:12 AM
MiloMorai wrote:

- No, that was the SeaFury.

The Sea Fury is based on the Tempest II?



- The last Tempest II sortie was flown 6 June 1951 in
- Malaysia.
- Afaik that is as close to Korea as they got.

Did the Tempest II serve during WWII? I'm trying to find some information on it.



Regards,

SkyChimp

http://members.cox.net/rowlandparks/corsairs.jpg

XyZspineZyX
09-04-2003, 02:20 AM
http://www.fleetairarmarchive.net/Aircraft/Seafury.html

A little late for WW2.

A cheap($$) book is the "InAction" #1117 (SeaFury) which gives a short development history.

http://www.stenbergaa.com/stenberg/taylor-greycap2.jpg


"Only a dead 'chamber pot' is a good 'chamber pot'!"

XyZspineZyX
09-04-2003, 02:31 AM
Salute Neil

Could you please post the entire Tempest test including the various comparisons?

I only have the test of the prototype with the Sabre IIA engine.

Thanks RAF74 Buzzsaw

XyZspineZyX
09-04-2003, 02:33 AM
MiloMorai wrote:
- SC, the Tempest II came after the Tempest V and VI.
- Due to technical troubles and a lack of engineers
- the Centaurus that powered the II did not see
- production till late in the war. About 2800 were
- built.

Tempest II did not see action during ww2. 2130 were contracted but only 452 were built.


Note the Fw-190 style cowling/i/smilies/16x16_smiley-very-happy.gif

http://user.tninet.se/~ytm843e/mw742.jpg



<center> http://www.stormbirds.com/images/discussion-main.jpg </center>

XyZspineZyX
09-04-2003, 02:45 AM
Yes Huckie the Fw did have some influence on the Tempest II./i/smilies/16x16_smiley-happy.gif Notice the NACA cowling on the Fw./i/smilies/16x16_smiley-very-happy.gif

2800 is the number of Centaurus engines built before WW2 ended.

The 1st Tempest Wing (183, 247 Sqd) was formed in Aug.1945 by Roland Beamont. WW2 did not official end til Sept '45.

Huckebein_FW wrote:
.
-
- Tempest II did not see action during ww2. 2130 were
- contracted but only 452 were built.
-
-
- Note the Fw-190 style cowling

http://www.stenbergaa.com/stenberg/taylor-greycap2.jpg


"Only a dead 'chamber pot' is a good 'chamber pot'!"

XyZspineZyX
09-04-2003, 02:53 AM
Huckebein_FW wrote:

- Note the Fw-190 style cowling

The Fw-190A had NACA influenced cowling!! /i/smilies/16x16_smiley-very-happy.gif /i/smilies/16x16_smiley-very-happy.gif /i/smilies/16x16_smiley-very-happy.gif /i/smilies/16x16_smiley-very-happy.gif



Edit: I see Milo already caught that /i/smilies/16x16_smiley-very-happy.gif /i/smilies/16x16_smiley-very-happy.gif /i/smilies/16x16_smiley-very-happy.gif /i/smilies/16x16_smiley-very-happy.gif
Edit again: And shall we mention the Pratt and Whitney influenced engine?


Regards,

SkyChimp

http://members.cox.net/rowlandparks/corsairs.jpg


Message Edited on 09/04/0305:55AM by SkyChimp

XyZspineZyX
09-04-2003, 03:59 AM
SkyChimp wrote:

- The Fw-190A had NACA influenced cowling!!


Can you elaborate on how, specifically, the FW190 had a NACA influenced cowling?



- And shall we mention the Pratt and
- Whitney influenced engine?


Pratt and Whitney influence for the BMW801? Please elaborate.


<center><img src= "http://www.luftwaffepics.com/LCBW4/FW190-A0-52.jpg" height=215 width=365>

<center>"We are now in a position of inferiority...There is no doubt in my mind, nor in the minds of my fighter pilots, that the FW190 is the best all-round fighter in the world today."

Sholto Douglas, 17 July 1942

XyZspineZyX
09-04-2003, 04:26 AM
FW190fan wrote:

- Can you elaborate on how, specifically, the FW190
- had a NACA influenced cowling?


From here:
http://koti.mbnet.fi/~jjuvonen/planes/fw-190a8.html
Kurt Tank submitted two proposals under a contract placed by the RLM in the autumn of 1937. The powerplants of the new designs were Daimler-Benz DB 601 liquid-cooled and then-new air-cooled BMW 139 radial. The radial was selected and detail design work begun in the summer of 1938. The prototype Fw 190 V1 first flight took place in June 1939 at Bremen. The second prototype flew in October 1939 and was armed with 2 x 13 mm and 2 x 7,92 mm mg. Both machines were fitted with large ducted spinners to reduce drag, but overheating broblems were experienced and an NACA cowling was substituted.

Look here for information on the developement of NACA cowling:
http://www.hq.nasa.gov/office/pao/History/SP-440/ch3-2.htm
or here...
http://www.centennialofflight.gov/essay/Evolution_of_Technology/cowling/Tech17.htm
or here...




- Pratt and Whitney influence for the BMW801? Please
- elaborate.

BMW licensed produced the Pratt and Whitney Hornet engine as the BMW 114. With increaded compression ratio and centrifugal supercharger it bacame the BMW 132 9 cylinder radial. BMW put two of these together on a single crankshaft to form the BMW 139. The BMW 139 powered the prototype Fw-190. Many design features of the 139 were carried over to the more compact BMW 801.



The American's influenced a German aircraft? Blasphemy!!!!

Regards,

SkyChimp

http://members.cox.net/rowlandparks/corsairs.jpg

XyZspineZyX
09-04-2003, 05:47 AM
SkyChimp,

Thanks for the info on the NACA cowling. I'll look into it.

It's my understanding that after the original ducted spinner did not provide sufficient cooling, the new cowling was the result of extensive wind tunnel tests within Germany itself, i.e. Volkenrode (Herman Goering wind tunnel)

It seems that here they extensively tested both the powerplants along with the cowlings together and made refinements based on this research. It is my understanding that this is where the cowling/ "power egg" arrangement for the serially produced FW190As was born.




- BMW licensed produced the Pratt and Whitney Hornet
- engine as the BMW 114. With increaded compression
- ratio and centrifugal supercharger it bacame the BMW
- 132 9 cylinder radial. BMW put two of these
- together on a single crankshaft to form the BMW 139.
- The BMW 139 powered the prototype Fw-190. Many
- design features of the 139 were carried over to the
- more compact BMW 801.


Wow, that's quite a s t r e t c h! /i/smilies/16x16_smiley-happy.gif (I hope you didn't pull anything) That was like the "Seven degrees of Kevin Bacon" or whatever it was.

Seriously though, I don't doubt there could have been some influence but it appears to be negligible at the very best.


- The American's influenced a German aircraft?
- Blasphemy!!!!

I agree with you dude, seems highly unlikely to me as well/i/smilies/16x16_smiley-very-happy.gif http://ubbxforums.ubi.com/infopop/emoticons/icon_razz.gif



<center><img src= "http://www.luftwaffepics.com/LCBW4/FW190-A0-52.jpg" height=215 width=365>

<center>"We are now in a position of inferiority...There is no doubt in my mind, nor in the minds of my fighter pilots, that the FW190 is the best all-round fighter in the world today."

Sholto Douglas, 17 July 1942

XyZspineZyX
09-04-2003, 07:27 AM
After reading through this thread, it strikes me that we are approching the subject of diving speed from the wrong direction. I would propose a slightly different angle of attack.

Consider two aircraft travelling at a known, constant speed, say 650km/h, and a known constant altitude, say 7000m. I picked this simply because this is the maximum speed of the Bf-109G-6 at that altitude, and the maximum speed of the P-47D-27 at that same altitude. These are two *extremely* different aircraft, that have similare level maximum speeds at this altitude.

The engery equation along the horizontal plane is the one everyone is familiar with:

Force Exerted by Prop/mass - Force exerted by drag/mass=0

or

Force Exerted by Prop - Force Exerted by Drag = 0


In the vertical direction we have:

Acceleration of Gravity + Force of Generated Lift/Mass = 0

It seems fairly reasonable to state that the Generated Lift must increase linearly with the mass of the aircraft, or, it takes twice as much gross force to keep a P-47D-27 flying level (6500kg mass), than it does to keep a Bf-109G-6 flying level (3100kg mass).

This force has to come from somewhere, and I am given to understand it is tapped out of the forward motion of the aircraft, as, essentially drag. So we now have a new term in the force equation along the horizontal plane: Induced Drag.

While I do not have a degree in aeronautical engineering, or aerodynamics, it seems reasonable that this induced drag, while not necessarily equal to the lift required, would scale linearly with it, for a given wing design.

I'm going to have to stop here; I've got to get up in about five hours to get some work done that's due in 13 hours, to be followed with an additional 10 hours of work.

My basic conclution is that there is an additional drag term in level flight, that is not present in diving flight: induced drag, which is responcible for keeping an aircraft in level flight, rather than plummeting towards the ground. This drag value is directly related to the mass of the aircraft, and gravity's effects upon it. In a dive it is no longer considered.

So, mass does not gain you anything in a dive, rather what mass does is costs you total speed in horizontal flight. However, for two aircraft of similare maximum speed in horizontal flight, yet of greatly dissimilare mass, the more massive plane must have a much higher force pushing it forward. This would imply in a dive, it would also have an equally great force pushing it downward, without the counterforce. This implies a greater accelleration, despite higher mass.

Additionally, even though we have horsepower values for these engines, at select altitudes, at select speeds, we do not actually have the direct force these engines were producing. We do, however, have concrete formulas to find the values of the parasitic drag and induced drag of these aircraft, given the speed, altitude, mass, wing airfoild, and drag of the aircraft. Those values we have very well documented. From those we can then find the effective force the engines are producing, at a given speed, and we can then turn that around, and find the aircraft's dive accelleration at that speed, and see what happenes.

Huck, just out of curiosity, how are you deriving the engine force for your calculations?

Harry Voyager

http://groups.msn.com/_Secure/0YQDLAswcqmIpvWP9dLzZVayPXOmo6IJ16aURujNfs4dDETH84 Q6eIkCbWQemjqF6O8ZfvzlsvUUauJyy9GYnKM6!o3fu!kBnWVh BgMt3q2T3BUQ8yjBBqECLxFaqXVV5U2kWiSIlq1s6VoaVvRqBy Q/Avatar%202%20500x500%20[final).jpg?dc=4675409848259594077

XyZspineZyX
09-04-2003, 08:45 AM
A bit more.


http://hometown.aol.co.uk/JStirlingBomber/Spit+drag+2.jpg

XyZspineZyX
09-04-2003, 08:54 AM
Title.


http://hometown.aol.co.uk/JStirlingBomber/Spit+drag+3.jpg

XyZspineZyX
09-04-2003, 08:56 AM
HarryVoyager wrote:
- After reading through this thread, it strikes me
- that we are approching the subject of diving speed
- from the wrong direction. I would propose a
- slightly different angle of attack.
-
- Consider two aircraft travelling at a known,
- constant speed, say 650km/h, and a known constant
- altitude, say 7000m. I picked this simply because
- this is the maximum speed of the Bf-109G-6 at that
- altitude, and the maximum speed of the P-47D-27 at
- that same altitude. These are two *extremely*
- different aircraft, that have similare level maximum
- speeds at this altitude.
-
- The engery equation along the horizontal plane is
- the one everyone is familiar with:
-
- Force Exerted by Prop/mass - Force exerted by
- drag/mass=0
-
- or
-
- Force Exerted by Prop - Force Exerted by Drag = 0
-
-
- In the vertical direction we have:
-
- Acceleration of Gravity + Force of Generated
- Lift/Mass = 0
-
- It seems fairly reasonable to state that the
- Generated Lift must increase linearly with the mass
- of the aircraft, or, it takes twice as much gross
- force to keep a P-47D-27 flying level (6500kg mass),
- than it does to keep a Bf-109G-6 flying level
- (3100kg mass).
-
- This force has to come from somewhere, and I am
- given to understand it is tapped out of the forward
- motion of the aircraft, as, essentially drag. So we
- now have a new term in the force equation along the
- horizontal plane: Induced Drag.
-
- While I do not have a degree in aeronautical
- engineering, or aerodynamics, it seems reasonable
- that this induced drag, while not necessarily equal
- to the lift required, would scale linearly with it,
- for a given wing design.
-
- I'm going to have to stop here; I've got to get up
- in about five hours to get some work done that's due
- in 13 hours, to be followed with an additional 10
- hours of work.
-
- My basic conclution is that there is an additional
- drag term in level flight, that is not present in
- diving flight: induced drag, which is responcible
- for keeping an aircraft in level flight, rather than
- plummeting towards the ground. This drag value is
- directly related to the mass of the aircraft, and
- gravity's effects upon it. In a dive it is no
- longer considered.
-
- So, mass does not gain you anything in a dive,
- rather what mass does is costs you total speed in
- horizontal flight. However, for two aircraft of
- similare maximum speed in horizontal flight, yet of
- greatly dissimilare mass, the more massive plane
- must have a much higher force pushing it forward.
- This would imply in a dive, it would also have an
- equally great force pushing it downward, without the
- counterforce. This implies a greater accelleration,
- despite higher mass.
-
- Additionally, even though we have horsepower values
- for these engines, at select altitudes, at select
- speeds, we do not actually have the direct force
- these engines were producing. We do, however, have
- concrete formulas to find the values of the
- parasitic drag and induced drag of these aircraft,
- given the speed, altitude, mass, wing airfoild, and
- drag of the aircraft. Those values we have very
- well documented. From those we can then find the
- effective force the engines are producing, at a
- given speed, and we can then turn that around, and
- find the aircraft's dive accelleration at that
- speed, and see what happenes.
-
- Huck, just out of curiosity, how are you deriving
- the engine force for your calculations?
-
- Harry Voyager

Harry the concept you're looking for is "aircraft density." Robert Shaw explains it in his book Fighter Combat on page 407 where he states "Discounting the effects of thrust, the acceleration of an aircraft in a dive is a function of its density (actually its mass) to drag. When two fighters are similar in all respects except that one is heavier, the heavier aircraft will accelerate faster in a dive and, assuming structural considerations allow, will have a faster terminal velocity. Likewise, with two fighters of the same weight, the cleaner one (i.e. the one with less drag) will dive better.

Given this principle the Jug should be able to outdive pretty much every plane in this sim by a good margin. But 1C has never fully accurately modelled AC density properly. Maybe in the next patch or in the next gen of sims this very important factor will be modelled properly.

I say this as an avid 190 fan, not a Jughead by the way. It'd be nice to see the 47 given its proper due. They would make worthy, if extremely difficult, opponents.

XyZspineZyX
09-04-2003, 09:38 AM
SkyChimp wrote:
- The Bf-109 had a black cross on it, it weighed less
- than a white star, increasing its power to weight
- ratio. So, the swastika, as a funtion of drag, was
- superior to the white star.
-
Of course my son /i/smilies/16x16_smiley-happy.gif

-
-
-- relatively small? it can change as much as it wants
-- before Mach divergence number.
-
- I didn't say "relatively small", I said "relatively
- constant." Or didn't you bother to read before
- responding?
-

I actually did and that's what sort of got to me in the first place. You wrote:
"As long as delta v remains low, such as in level flight. But the speed at which Cd begins to rise dramatically is easily reached in even a short dive."

delta v I assume means speed change? Now what did you write again?Cd raise dramatically even in a short dive? Right there, caught again, hands in the cookie jar introducing gas dynamics according to Chimp.

-- Easily? It will take more like 1500 m from 3000 m
-- for P-47
-- to reach 700 km/h (Ma=0.6) starting from 400 km/h.

As this shows that even in a short dive comes into interesting light, now doesn't it?/i/smilies/16x16_smiley-wink.gif
-
- I see, your a$$ has been doing the reading. I'm
- talking about comparable aircraft. I thought that
- might have been evident to a "scientist."
-
You can compare what you wish but your "theory" is just too revolutionary for my concervative mind to swallow. After you get a patent for it feel free to come back to me. You based your "theory" on two sets of data and pulled that "generally" right out of the first difference that meet the eye, namely the Cd in the incompressible flow saying high Cd must be worse. Just like that? And added even that generally, just like that, now didn't you?

- I'm saying Cd for the P-51 begins to rise noticeably
- at Mach .6. It rises more dramatically as speed
- increases with a serious upturn at about mach .7.
- What's hard for you to understand about that.
-

Just your trial to make a mess out of it. That serious and different final upturn comes from the first shockwave formations which is individual for different aircraf (and closer to Ma=0.8), does not have too much to do with Cd though...There is already upturn in compressible subsonic area but it's about same for all. (relative change in cd vs Ma)

- Perhaps you can come up with a better way to explain
- that the terminal mach of the Bf-109F was mach .085,
- while that of the P-47C was mach .86. Perhaps you
- can explain why the Bf-109 entering into
- compressibility well before the P-47?
-
I actually did not bring the compressability into discussion, did I? I haven't even bothered to argue those "terminal Machs" and I am not even going to get started, why? I have all the time tried to explain that at low to medium height your changes of outdiving anybody are slim. Namely you don't easily land to this velocity area (except from a prolonged dive from high-alt) even if you try to convince the children around here that transonic fligh was everyday occurence. You see, I am not trying to say that P-47 wasn't a good diving aircraft or dispute the high top speeds that it can reach. I am trying to say that outdiving does not automatically happen everywhere at all speeds. Boy's own may disagree with me but I think I am not going to loose any sleep over that.

-I agree, low level, shallow angle, dive acceleration will favor the lighter German planes.

Can we also have most of the russians as well then we have it all nicely wrapped up (and scrap that shallow please)? This would actually sum it up quite nicely. What I have been trying to implicate is that P-47 does not generally outdive anybody anywhere just like that but that instead you should try to use some consideration where to apply this trick. Unfortunately, you seldom enter this scenario in a DF server or in an online war, before you start having those B-17s doing the high alt bomb job. In this perspective P-47 came too early to the game and causes unnecessary frustrations, P-51 would have been much more suitable.

-------------------------------------
http://people.freenet.de/hausberg/schimpf.gif



Message Edited on 09/04/0301:07PM by Ugly_Kid

XyZspineZyX
09-04-2003, 10:27 AM
FW190fan wrote:
- tests within Germany itself, i.e. Volkenrode (Herman
- Goering wind tunnel)

The windbag had a wind tunnel? It seems somehow fitting!

XyZspineZyX
09-04-2003, 10:30 AM
Ugly_Kid wrote:
- SkyChimp wrote:
-- The Bf-109 had a black cross on it, it weighed less
-- than a white star, increasing its power to weight
-- ratio. So, the swastika, as a funtion of drag, was
-- superior to the white star.
--
- Of course my son /i/smilies/16x16_smiley-happy.gif -
--
--
--- relatively small? it can change as much as it wants
--- before Mach divergence number.
--
-- I didn't say "relatively small", I said "relatively
-- constant." Or didn't you bother to read before
-- responding?


I'm the one who was talking about small delta v. I
was interested in what the difference in instantaneous
acceleration at various points would be. For small delta
v then Cd(v0) and Cd(v0+delta v) would be essentially the
same.

XyZspineZyX
09-04-2003, 10:46 AM
SkyChimp wrote:
- Let's assume for the moment that the P-47 being
- compared IS an older -21 engined model. The P-47C-1
- was capable of
- 340 mph on the deck. Was the Tempest II capable of
- 420 mph on the deck?

Normally quoted is 410mph at sea level for the Tempest II.
(For comparasion, the Tempest V could do 389).

- At 12,000 feet the Tempest was 70 mph faster. The
- P-47C-1 could do 385 mph at 12,000 feet: the Tempest
- II could do 455 mph?

Normally quoted is 442 at 15000 ft. So 455 might
be a bit high, but it is in the ball park, and 455 is
an estimate based on the amount it was measured faster
than the P47, without absolute figures being quoted in
the report. If the P47 was performing under spec at
that altitude, that may explain why the Tempest II
was doing so well in comparasion. In other words, you
are extrapolating to arrive at the 455 figure, and then dismissing it, without looking at other possible causes.

I've also seen 460mph quoted for about 25,000 or 30,000
feet, which compares favourably with the P47M, but that's
from memory, so it could be wrong.

- These are some truly amazing numbers for the Tempest
- II. I'm stunned the RAF felt a need to develope a
- Tempest V.
- (Note: This comment is tongue in cheek to all you
- RAF plane lovers with no sense of humor or sarcasm.)

I hope the sarcasm means you do understand that
the V was developed first!

- 1) The Tempest II was a stellar performer that
- performed well in excess of it's published specs.

It could have also been that the Tempest II tested
was performing slightly below published specs. Basically
if the P47 was 5 mph slower than published, and the Tempest
II 5 mph faster, the difference is explained. That's
the sort of variation you can get from plane to plane.

With regards to climb the Tempest II had an average of 3300 fpm from seal level to 15000 (4.5 mins to 15000)

- Either way, the veracity of the test is
- questionable.

Why so? Basically you are dismissing the performance
of the Tempest II by guessing which US model number
the Thunderbolt II tested was. The RAF used a different
system, so it is hard to know exactly what it was, so
maybe we should wait until Neil gives us more information,
if he has it, which may tie down the exact P47 model.





Message Edited on 09/04/0309:59AM by AaronGT

XyZspineZyX
09-04-2003, 10:50 AM
MiloMorai wrote:
- SC, the Tempest II came after the Tempest V and VI.

The Tempest VI, AFAIK, came after the Tempest II,
the VI being a development of the II.

It's a shame that the Tempest I was abandoned due
to engine technical issues, as the performance
of the prototype suggest it might have been slightly
faster then the II. It's hard to predict from
the prototupe, though.

XyZspineZyX
09-04-2003, 11:41 AM
Neil, thank you for the Spit dive docs. I wrote a reply for this thread earlier, then junked it, because I knew it would get in to the same argumen with Skychimp and Slickun, and I didn't have the docs to back it up.

SkyChimp wrote:

- But if I'm right, all bubble-top versions of the
- P-47 were serially produced with water injection.
- Why not this one?
-
Could be that the RAF removed it, or it simply wasn't functional in this aircraft.

- Let's assume for the moment that the P-47 being
- compared IS an older -21 engined model. The P-47C-1
- was capable of
- 340 mph on the deck. Was the Tempest II capable of
- 420 mph on the deck?

From docs Neil posted previously, the Tempest II with water injection and water injection could do 426 mph at sea level. With 150 octane OR 100/130 and water injection, it could do 412.

- At 12,000 feet the Tempest was 70 mph faster. The
- P-47C-1 could do 385 mph at 12,000 feet: the Tempest
- II could do 455 mph?

Tempest II at 12,000ft 451mph

- 4) The Tempest II was 2,000 fpm better than the
- Thunderbolt II at sea level. The P-47C-1 could
- manage just 2,750 fpm at sea level. Did the Tempest
- II climb at 4,750 fpm at sea level?

Maximum power with 150 octane and water injection was 2900hp, so the climb rate sounds reasonable.

- These are some truly amazing numbers for the Tempest
- II. I'm stunned the RAF felt a need to develope a
- Tempest V.
- (Note: This comment is tongue in cheek to all you
- RAF plane lovers with no sense of humor or sarcasm.)

Okay, but for the humor impaired, the Tempest II came after the Tempest V. (Some people would expect logic in plane numbering. I've seen countless people who think the Spit XVI must have been an improved Spit XIV)

- 1) The Tempest II was a stellar performer that
- performed well in excess of it's published specs.

Those figures actually fit the published specs. Can't speak for the thunderbolt, 'cause I don't know what it's performance should be.

XyZspineZyX
09-04-2003, 12:35 PM
Nope Aaron, the VI used a Sabre engine and was a development of the Tempest V (to use the Sabre engine of 2340hp). Tempest V, MM595, was used for the prototype VI.

Sounds good./i/smilies/16x16_smiley-wink.gif (but see above for why I said)

The VI did enter RAF service well after the II. (15 months later)

AaronGT wrote:
-
-
-
- The Tempest VI, AFAIK, came after the Tempest II,
- the VI being a development of the II.
-
-

http://a1276.g.akamai.net/7/1276/734/625ed428e022ef/www.harley-davidson.com/PR/MOT/2004/Softail/images/DOM/img_Softail_FXST.jpg

http://www.redneckengineering.com/photogallery/photo23581/curves-done-03.jpg

"Only a dead 'chamber pot' is a good 'chamber pot'!"

XyZspineZyX
09-04-2003, 12:51 PM
AaronGT wrote:
- I'm the one who was talking about small delta v. I
- was interested in what the difference in
- instantaneous
- acceleration at various points would be. For small
- delta
- v then Cd(v0) and Cd(v0+delta v) would be
- essentially the
- same.
-

Page three 12th post, second from SkyChimp on that page, part:"Airy analysis on aerodynamic efficiency". Sorry, I don't think I'm not going to let him off the hook, his prosa has so much fertilizers in it that it turns lakes into wasteland.

You also showed courtesy of formulating your stuff whether it was so or not instead of boldly insisting that it's so.

I am not saying everything is pico bello in the game but it would not necessarily harm to remember that the dev. team still do know something. As it can be seen the current behaviour and the fact that P-47 does not outdive for example Yak-3 with ease can be still easily justified.

Currently IMHO and from my subjective viewpoint we have excellent sim with sound problems. I would not have wasted as many positive words about previous versions.

-------------------------------------
http://people.freenet.de/hausberg/schimpf.gif



Message Edited on 09/04/03 01:21PM by Ugly_Kid

Message Edited on 09/04/0301:26PM by Ugly_Kid

XyZspineZyX
09-04-2003, 01:41 PM
ROFMALOL, and the attack on sanity rages on !!!!!

Highest Mach speed, 0.89 for Spit, 0.8 !!!! for Mustang !

/i/smilies/16x16_smiley-very-happy.gif /i/smilies/16x16_smiley-very-happy.gif /i/smilies/16x16_smiley-very-happy.gif /i/smilies/16x16_smiley-very-happy.gif


Ohohohoo, please stop it, I fell of my chair... !! /i/smilies/16x16_smiley-very-happy.gif /i/smilies/16x16_smiley-very-happy.gif /i/smilies/16x16_smiley-very-happy.gif


http://vo101isegrim.piranho.com/FB-desktopweb.jpg
'Only a dead Indianer is a good Indianer!'

Vezérünk a Bátorság, K*sérµnk a Szerencse!
(Courage leads, Luck escorts us! - Historical motto of the 101st Puma Fighter Regiment)

Flight tests and other aviation performance data: http://www.pbase.com/isegrim

XyZspineZyX
09-04-2003, 02:01 PM
Unlike your Messish!t graphs, which you occasionally post Issy, which were factory theoretical performance calculations, the Spit data came from actual a/c flight testing.


Vo101_Isegrim wrote:
-
-
- ROFMALOL, and the attack on sanity rages on !!!!!
-
- Highest Mach speed, 0.89 for Spit, 0.8 !!!! for
- Mustang !
-
-

http://a1276.g.akamai.net/7/1276/734/625ed428e022ef/www.harley-davidson.com/PR/MOT/2004/Softail/images/DOM/img_Softail_FXST.jpg

http://www.redneckengineering.com/photogallery/photo23581/curves-done-03.jpg

"Only a dead 'chamber pot' is a good 'chamber pot'!"

XyZspineZyX
09-04-2003, 02:08 PM
MiloMorai wrote:
- Nope Aaron, the VI used a Sabre engine and was a
- development of the Tempest V (to use the Sabre
- engine of 2340hp). Tempest V, MM595, was used for
- the prototype VI.

Right you are. I was getting confused about the fact
that some improvements over the V that were developed
in the II were added to the V to form the VI. Quite
a moutful of a sentence! You are right though, and I
was wrong.

XyZspineZyX
09-04-2003, 02:23 PM
AaronGT wrote:
-
-
- You are right though, and I
- was wrong.
-

no right, no wrong./i/smilies/16x16_smiley-happy.gif

http://a1276.g.akamai.net/7/1276/734/625ed428e022ef/www.harley-davidson.com/PR/MOT/2004/Softail/images/DOM/img_Softail_FXST.jpg

http://www.redneckengineering.com/photogallery/photo23581/curves-done-03.jpg

"Only a dead 'chamber pot' is a good 'chamber pot'!"

XyZspineZyX
09-04-2003, 02:45 PM
AaronGT wrote:

- The windbag had a wind tunnel? It seems somehow
- fitting!

/i/smilies/16x16_smiley-very-happy.gif

Yeah, I think Herman stood at one end and they just stuck the tunnel in his mouth and he blew. It then became the most powerful wind tunnel in the world.

Seriously though, my point was that the complete power egg/engine, cowling, induction fan, were tested as a complete unit at Volkenrode, and from these tests we get the cowling/cooling arrangement on the serially produced FW190A.


Unless of course all "close-cowled" radial engines are automatically considered to be NACA cowlings based on their research in the late 1920s. Is this the case?




<center><img src= "http://www.luftwaffepics.com/LCBW4/FW190-A0-52.jpg" height=215 width=365>

<center>"We are now in a position of inferiority...There is no doubt in my mind, nor in the minds of my fighter pilots, that the FW190 is the best all-round fighter in the world today."

Sholto Douglas, 17 July 1942

XyZspineZyX
09-04-2003, 03:03 PM
FW190fan wrote:
- Unless of course all "close-cowled" radial engines
- are automatically considered to be NACA cowlings
- based on their research in the late 1920s. Is this
- the case?


Yes any cowling around a radial engine was called from late 20s NACA cowling. Something really significant to mention about Fw-190, if you're looking for some trolling of course.

Also BMW-801 was an original design.


<center> http://www.stormbirds.com/images/discussion-main.jpg </center>

Message Edited on 09/04/0309:08AM by Huckebein_FW

XyZspineZyX
09-04-2003, 03:17 PM
MiloMorai wrote:
- Unlike your Messish!t graphs, which you occasionally
- post Issy, which were factory theoretical
- performance calculations, the Spit data came from
- actual a/c flight testing.
-


Sorry Briddy, all my curves are for actual German, Soviet, British or Finnish curves, unless otherwise noted.

Actual flight testing for Spit? LOL. Not unless they were all drunk. /i/smilies/16x16_smiley-very-happy.gif

The Spit dive data Neil posted is a joke. According to NACA, and even by most British authors as well. It`s so ridiculus, that it isn`t even worth to discuss. It was started based on a pilot story about exceeding 600mph in a dive (in which he was unconcious...). Then the it appeared in The Aeroplane magazine, in early 1940. Then they tried to back it up with a laughable test, in which they didn`t use corrections at all, only pitot tube and accelerometer readings (hence EAS in the table - Estimated Air Speed).

The other interesting part is the acceleration... LOL.. too bad they listed that one, too. Very telling to those who have some idea on it.


But, as Niklas said long ago on this, propaganda is to make people feel good, especially those who don`t have enough brains to judge wheter it makes sense or not.

Such people even believe that the Spit, which was OUTDIVED IN EVERY SINGLE FLIGHT TEST AND ON THE BATTLEFIELD BY EVERY OTHER AIRCRAFT POSSIBLE, dozens of the type broking up in dives, is the WW2 champion of Mach number, beating even later British jets, even though NACA research shows it`s impossible, and the best part of the joke is, not in a near-vertical, but IN A 45 DEGREE dive, ROFMALOL. /i/smilies/16x16_smiley-very-happy.gif /i/smilies/16x16_smiley-very-happy.gif And by no less than 0.1 Mach, LOL. /i/smilies/16x16_smiley-very-happy.gif /i/smilies/16x16_smiley-very-happy.gif

http://vo101isegrim.piranho.com/FB-desktopweb.jpg
'Only a dead Indianer is a good Indianer!'

Vezérünk a Bátorság, K*sérµnk a Szerencse!
(Courage leads, Luck escorts us! - Historical motto of the 101st Puma Fighter Regiment)

Flight tests and other aviation performance data: http://www.pbase.com/isegrim

XyZspineZyX
09-04-2003, 03:40 PM
HarryVoyager wrote:
- My basic conclution is that there is an additional
- drag term in level flight, that is not present in
- diving flight: induced drag, which is responcible
- for keeping an aircraft in level flight, rather than
- plummeting towards the ground. This drag value is
- directly related to the mass of the aircraft, and
- gravity's effects upon it. In a dive it is no
- longer considered.


Induced drag is very easy to plot:

Di = (cl^2/(PI()*e*AR))*(0.5*air_density*speed^2*wing_area)

where

cl = coef of lift
Pi = 3.14
e = Oswald Factor
AR = aspect ratio

Indeed in dive induced drag is smaller than in level flight, and it is true that it varies with coef of lift (not lift itself) and lift has to counter the weight even in dive.

In dive lift is equal with weight*cos(dive_angle)
Please note that if we are in level flight, dive angle being 0, we have cos(0) = 1 so lift equals weight. In a 30 degree dive lift is only 86% of weight and so on.

But induced drag is not a concern at high speed, it's only 3 or 4% of total drag at max speed in level flight for a ww2 fighter (with a normal aerodynamic config). The reason for this is the fact that induced drag varies with coeficient of lift not with lift itself, meaning that when flying with 550km/h you'll get the same lift as when flying 250km/h using a much smaller angle of attack (and coeficient of lift) and therefore less induced drag.

In my estimation the dive angle effect on lift was considered.



- Huck, just out of curiosity, how are you deriving
- the engine force for your calculations?


thrust = 550*hp*propeller_efficiency/speed

speed in feet per second

usually propeller efficiency varies from sligthly below 60% at take-off to sligthly above 80% at max speed (above max speed it decreases again)

Of course you can get a better estimation of thrust if you have the dynamic hp ratings and exhaust thrust, the improvement in accuracy is around 3%. But if you don't have both you can't use just one of them because you'll get erroneous results. Most of the time in ww2 calculations thrust was calculated with the formula above.



<center> http://www.stormbirds.com/images/discussion-main.jpg </center>

XyZspineZyX
09-04-2003, 03:43 PM
Not 'talking' about your privately made curves Barbi./i/smilies/16x16_smiley-very-happy.gif

Barbi, as usual you can't post a civil post but must include your usual derogatory comments. Lots of intelligence shown for sure and you call yourself a lawyer./i/smilies/16x16_smiley-very-happy.gif The lawyers I know have MUCH MORE intelligence than you show.



Vo101_Isegrim wrote:
-
- Sorry Briddy, all my curves are for actual German,
- Soviet, British or Finnish curves, unless otherwise
- noted.
-
- Actual flight testing for Spit? LOL. Not unless they
- were all drunk. /i/smilies/16x16_smiley-very-happy.gif -
- The Spit dive data Neil posted is a joke. According
- to NACA, and even by most British authors as well.
- It`s so ridiculus, that it isn`t even worth to
- discuss. It was started based on a pilot story about
- exceeding 600mph in a dive (in which he was
- unconcious...). Then the it appeared in The
- Aeroplane magazine, in early 1940. Then they tried
- to back it up with a laughable test, in which they
- didn`t use corrections at all, only pitot tube and
- accelerometer readings (hence EAS in the table -
- Estimated Air Speed).
-
- The other interesting part is the acceleration...
- LOL.. too bad they listed that one, too. Very
- telling to those who have some idea on it.
-
-
- But, as Niklas said long ago on this, propaganda is
- to make people feel good, especially those who don`t
- have enough brains to judge wheter it makes sense or
- not.
-
- Such people even believe that the Spit, which was
- OUTDIVED IN EVERY SINGLE FLIGHT TEST AND ON THE
- BATTLEFIELD BY EVERY OTHER AIRCRAFT POSSIBLE, dozens
- of the type broking up in dives, is the WW2 champion
- of Mach number, beating even later British jets,
- even though NACA research shows it`s impossible, and
- the best part of the joke is, not in a
- near-vertical, but IN A 45 DEGREE dive, ROFMALOL.
- /i/smilies/16x16_smiley-very-happy.gif /i/smilies/16x16_smiley-very-happy.gif And by no less than
- 0.1 Mach, LOL. /i/smilies/16x16_smiley-very-happy.gif /i/smilies/16x16_smiley-very-happy.gif -
-

http://a1276.g.akamai.net/7/1276/734/625ed428e022ef/www.harley-davidson.com/PR/MOT/2004/Softail/images/DOM/img_Softail_FXST.jpg

http://www.redneckengineering.com/photogallery/photo23581/curves-done-03.jpg

"Only a dead 'chamber pot' is a good 'chamber pot'!"

XyZspineZyX
09-04-2003, 04:04 PM
MiloMorai wrote:
-
- Not 'talking' about your privately made curves
- Barbi.
-

Why should I need that ? They are based on flight tests just as well, unlike some Spitfire dive tests, which fell into the estimated, propaganda purpose category.



-
- Barbi, as usual you can't post a civil post but must
- include your usual derogatory comments.

What 'derogratory comments', Briddy? Oh, I forgot you just play the old tunes again and again and again, like a broken record.


- Lots of
- intelligence shown for sure and you call yourself a
- lawyer. The lawyers I know
- have MUCH MORE intelligence than you show.


ROFMALOL. /i/smilies/16x16_smiley-very-happy.gif I doubt you have ever met one.


BTW, the old czech sewing machine in your sig, really nice. It remotely resambles a motorbike (or I am just hallucinating?) Is it for sale ? My grandma would surely love it. /i/smilies/16x16_smiley-happy.gif


http://vo101isegrim.piranho.com/FB-desktopweb.jpg
'Only a dead Indianer is a good Indianer!'

Vezérünk a Bátorság, K*sérµnk a Szerencse!
(Courage leads, Luck escorts us! - Historical motto of the 101st Puma Fighter Regiment)

Flight tests and other aviation performance data: http://www.pbase.com/isegrim

XyZspineZyX
09-04-2003, 04:15 PM
Your grandma would mess her drawers with a stinking mess of bodily waste if she ever got on it, just like you would Barbi. Big mouths and tiny guys go together.

As usual more derogatory remarks/insults from Barbi.


Vo101_Isegrim wrote:

-
- Why should I need that ? They are based on flight
- tests just as well, unlike some Spitfire dive tests,
- which fell into the estimated, propaganda purpose
- category.
-
-
- What 'derogratory comments', Briddy? Oh, I forgot
- you just play the old tunes again and again and
- again, like a broken record.
-
-
- ROFMALOL. /i/smilies/16x16_smiley-very-happy.gif I doubt you have ever
- met one.
-
-
- BTW, the old czech sewing machine in your sig,
- really nice. It remotely resambles a motorbike (or I
- am just hallucinating?) Is it for sale ? My grandma
- would surely love it.

http://a1276.g.akamai.net/7/1276/734/625ed428e022ef/www.harley-davidson.com/PR/MOT/2004/Softail/images/DOM/img_Softail_FXST.jpg

http://www.redneckengineering.com/photogallery/photo23581/curves-done-03.jpg

"Only a dead 'chamber pot' is a good 'chamber pot'!"

XyZspineZyX
09-04-2003, 04:23 PM
Vo101_Isegrim wrote:
- Aeroplane magazine, in early 1940. Then they tried
- to back it up with a laughable test, in which they
- didn`t use corrections at all, only pitot tube and
- accelerometer readings (hence EAS in the table -
- Estimated Air Speed).

EAS is equivalent airspeed Isegrim, not "Estimated Air Speed". EAS is indicated air speed corrected for installation (which gives you calibrated air speed or CAS), and then corrected for compressibility to give equivalent air speed. So, you can think of it as a very accurate indicated air speed. It can also easily be converted to true air speed by simply dividing by the square root of the density ratio. When flying at any speed where compressibility becomes important (avove say Mach 0.5), EAS is the correct value to use in aerodynamics calculations.

BTW, the claimed Spitfire dive speed that has been dismissed by many engineers is a claim in an aeroplane magazine (I think in the early 90's actually) for 0.96 Mach. The 0.89 posted in the test by Neil seems reasonable to me - there certainly is no law in physics that says "no propeller driven aircraft can exceed Mach 0.89". Yes, prop efficiency is horrible at that speed, and the Spitfire suffers from a separation induced shock right in front of the windscreen that appears at fairly low Mach numbers (which I have to add was probably not the case for all marks), yet from everything I have read in the literature and test data that I have seen, the drag divergence Mach number of the Spitfire was surprisingly high. It is an interesting phenomenon, since the efficiency of the Spitfire was not the best at high speeds in level flight when compared to for instance the P-51. It is "interesting", but not by any means "impossible" - flow in the transonic region is very complex and very different for each aircraft geometry.

Regards,
Oryx

XyZspineZyX
09-04-2003, 04:30 PM
Now why would my grandma get on a sewing machine..? She would just sit down next to it, and the thing would emmit some squeeze little high-pitch sound...

Oh, Jesus, I just got it! This is a picture of a MOTORBIKE of somewhat ancient desing, really! Sorry for not being able to recognize that for the first glance. Looks a bit outdated, didn`t you ever consider replacing it with something less archaic, but more modern ?

Something that could go 300 kph in say, 4-5 seconds, rather than 30 kph in 10 seconds?

Like a Honda Blackbird. Uhm, that`s where motorcycles really begin !

http://luzonmotorcycle.com/gallery/Originals/cbr1100xx-full.jpg



But after all, why replace it, if it was good for grandpa, too?

http://vo101isegrim.piranho.com/FB-desktopweb.jpg
'Only a dead Indianer is a good Indianer!'

Vezérünk a Bátorság, K*sérµnk a Szerencse!
(Courage leads, Luck escorts us! - Historical motto of the 101st Puma Fighter Regiment)

Flight tests and other aviation performance data: http://www.pbase.com/isegrim

XyZspineZyX
09-04-2003, 04:37 PM
Just to drift back to the original subject of this thread...

I just flew an interesting dogfight against an AI FW-190A-8, in a P-47D-10, FB v1.0. We had a rather long tail chase, where he tried the circle climb, so I went to a straight, shallow 2,000ft/m climb, and extended away from him. We continued this straight up to contrail altitude, I'm guessing around 23,000 ft, when I turned and bounced him, with at least a 3,000ft advantage.

It was a nearly perfect set up, too. I ended up directly behind him, at about 300 mph IAS, with an energy advantage of, I'm guessing 30-40mph (he was diving away from me as well). I dropped down a little bit to get a good raking shot on him, when he broke hard right, did about a 270 degree barrel roll (rudder and elevators involved) and pull away to the left. I threw the stick and rudder hard left, and pulled back to barrel roll left and follow him, and...nothing happened... It was sort of amazing. Remember, this is with the Pre-patch Fw-190, that everyone constantly compained had to little control authority at high speeds.

Some very interesting impressions stuck out in my mind after this flight. I cannot out dive a FW-190, without an initial E advantage. I can, however, extend from one in an optimized climb. Manuvering above 250mph IAS is difficult, above 300 mph IAS it is impossible.

These impressions strike me as very odd. I saved the track, btw, so anyone who wants to watch it, just let me know and I can email it to them. It is in FB 1.0 trk format however, and would require usage in a FB 1.0 installation. Not that you can watch tracks at all in 1.1b.

The file is 715kb. It was a *long* extention.

Harry Voyager

http://groups.msn.com/_Secure/0YQDLAswcqmIpvWP9dLzZVayPXOmo6IJ16aURujNfs4dDETH84 Q6eIkCbWQemjqF6O8ZfvzlsvUUauJyy9GYnKM6!o3fu!kBnWVh BgMt3q2T3BUQ8yjBBqECLxFaqXVV5U2kWiSIlq1s6VoaVvRqBy Q/Avatar%202%20500x500%20[final).jpg?dc=4675409848259594077

Message Edited on 09/04/0310:38AM by HarryVoyager

XyZspineZyX
09-04-2003, 04:47 PM
Yes this problem often happens, but we have no good proof for it.

1C team should add a speed bar in tracks for enemy plane. This would be the only way we can check if energy loss is correctly modelled.


<center> http://www.stormbirds.com/images/discussion-main.jpg </center>

XyZspineZyX
09-04-2003, 04:57 PM
SkyChimp wrote:

- Just how did that wonderful Fw-190 compare at
- realisitic combat altitudes, say 20-30,000 feet.


Unfortunately, combat was not restricted to the 5-7,000ft. area of high altitude where the P-47 had a clear advantage over the non-turbo FW190A. It was fought from 30,000ft all the way down to the deck.

I'm of the opinion that the overwhelming majority of WWII combat took place BELOW 25,000ft. Even in the West.

"Realistic combat altitude" is from sea level to 30,000ft, and the Thunderbolt like any other fighter couldn't always confine combat to the area of the sky where it had an advantage.




- (And we won't even worry about the fact that the
- Fw-190A was nearly incontrollable at 25,000 feet and
- over.)


Fact my ***, and you know it/i/smilies/16x16_smiley-very-happy.gif

For example on April 29, 1943 P-47s of the 56th FG were flying at *28,000ft.* when they were bounced *from above* by FW190A-5s(possibly A-4s) of JG/26 which quickly downed two P-47s in a quick pass.


Eric Brown, flying a captured FW190A-4 had this to say:

" I ascertained that the service ceiling was around 35,000ft." (Wings of the Luftwaffe - p.85)

That's 10,000ft. above your "incontrollable at 25,000ft." hooey.

Even charts from 1942 show the BMW801 putting out 1300hp at 25,000ft before higher boost pressures, supercharger gear ratios, and of course, GM-1 was made available.

References of course for the FW190 flying above 30,000ft. on bomber intercept missions are massive.

I suppose you base this stuff on the NACA bench test of a BMW801 in April, 1945?



<center><img src= "http://www.luftwaffepics.com/LCBW4/FW190-A0-52.jpg" height=215 width=365>

<center>"We are now in a position of inferiority...There is no doubt in my mind, nor in the minds of my fighter pilots, that the FW190 is the best all-round fighter in the world today."

Sholto Douglas, 17 July 1942

XyZspineZyX
09-04-2003, 05:04 PM
- All the 0,89 and above Mach and co. hypes started
- with a single accident, when a British pilot went
- into a dive with a Spit, lost conciousness, and when
- recovered found himself in a climb.

Okay.

- Now, the Brits managed somehow to conlclude from
- this that he had reached .89 Mach or so, and,
- probably to boost morale (at the time many Spits
- lost wings in dives), improvised a series of *tests*
- to prove it. Like the one excerpt posted by Neil.

Okay, now I have a problem.

The Spit that famously entered a dive when the pilot blacked out, and then recovered, was flown by Flight Lieutenant E.C. Powles. The event happened in 1952.

If you look at the date of the tests Neil has posted, it's 1944.

Regardless, what's the point of falsifying a classified dive test? The 0.89 number from the tests was never released during wartime.

Now, you might claim that the story from the pilot blacking out in 1952 and reporting mach 0.9+ isn't the one that "inspired" the tests 8 years earlier, and that there really was a story along similar lines in The Aeroplane in 1940. But I have never seen any reference to it. The story from 1952 is well known, b ut the only reference to the 1940 story in The Aeroplane I have ever seen is you, and Niklas on the AH board who originally claimed it.

- The Spit dive data Neil posted is a joke. According
- to NACA, and even by most British authors as well.

Right. Thunderbolt reaches mach 0.86, despite it's thick wings, but Spit, with the thinnest wings on any major prop fighter, at 0.89 is a joke.

- Then they tried
- to back it up with a laughable test, in which they
- didn`t use corrections at all, only pitot tube and
- accelerometer readings (hence EAS in the table -
- Estimated Air Speed).

As has already been pointed out, EAS is equivalent air speed, and is corrected for compressibility.

As to the instrumentation for the tests, the standard pitot tubes were replaced by ones at the wingtip, a 14" pitot comb was trailed behind the wing, and extra instuments were installed behind the pilot's seats, photographed at 1 second intervals during the dives.

- The other interesting part is the acceleration...
- LOL.. too bad they listed that one, too. Very
- telling to those who have some idea on it.

What do you mean? G is a measure of acceleration of the plane, in all axis. It doesn't mean it gained speed at 0.84 G or whatever.

- But, as Niklas said long ago on this, propaganda is
- to make people feel good, especially those who don`t
- have enough brains to judge wheter it makes sense or
- not.

So Niklas IS your source for "The Aeroplane story".

How is a classified test, not published until after the war, propoganda?

- Such people even believe that the Spit, which was
- OUTDIVED IN EVERY SINGLE FLIGHT TEST AND ON THE
- BATTLEFIELD BY EVERY OTHER AIRCRAFT POSSIBLE,

Hardly. But tests comparing aircraft would focus on dive acceleration, not all out top end dive speed. Few pilots would be brave enough, or stupid enough, to dive to such speeds in combat.

- the best part of the joke is, not in a
- near-vertical, but IN A 45 DEGREE dive,

Why do you find it strange that such speeds could be reached in a 45 deg dive? There's a lot of the use of the term "terminal speed" in this thread, usually innapropriately. Terminal speed is the maximum speed an object can reach. After that, it will go no faster. Skydivers, for example, have a terminal speed.

Very few WW2 fighters had a terminal speed, in that sense. Almost all would continue accelerating until they broke up. Put a Mustang or Thunderbolt or Spitfire in a 90 deg vertical dive from altitude, and hold it there, and the plane will break up before it hits the ground.

XyZspineZyX
09-04-2003, 06:06 PM
Let me poke a hole here and ask Ugly or Oryx a question....


apier wrote:
-
- Harry the concept you're looking for is "aircraft
- density." Robert Shaw explains it in his book
- Fighter Combat on page 407 where he states
- "Discounting the effects of thrust, the acceleration
- of an aircraft in a dive is a function of its
- density (actually its mass) to drag. When two
- fighters are similar in all respects except that one
- is heavier, the heavier aircraft will accelerate
- faster in a dive and, assuming structural
- considerations allow, will have a faster terminal
- velocity. Likewise, with two fighters of the same
- weight, the cleaner one (i.e. the one with less
- drag) will dive better.
-
- Given this principle the Jug should be able to
- outdive pretty much every plane in this sim by a
- good margin. But 1C has never fully accurately
- modelled AC density properly. Maybe in the next
- patch or in the next gen of sims this very important
- factor will be modelled properly.

The Shaw material is fine except it doesn't directly apply to say the P47 vs the FW190 in most models of either I know of. Why? Because the powerloading is not similar for one and I'm sure that others can be come up with.


The question I have is: Don't the wings produce lift only on the basis of speed and AOA? And doesn't that create induced drag regardless of being going level or straight down? I seem to remember that planes that point steeply down do not fly as steeply downwards as they are pointed because the lift from the wings adds to the horizontal vector of the flight path. This would explain to me some, maybe much of why lower wingloaded planes do not dive as well.


Neal

XyZspineZyX
09-04-2003, 06:20 PM
I think Oryx will fill in the gaps, but a wing may produce lift with zero AoA (very often does, matter of design), but there is also an AoA (negative, in this case) that will have no lift.

You might also consider continued inverted flight (-1g) and your wing works the other way around (not as effectively as right way up but it does). I make an educated quess but I assume that aerobatic aircraft probably often have symmetric profile (being also effective in inverted flight).

But yes to answer, your dive would propably have to appear deeper as it actually is. This can be seen very well with higher flap angles where curvature of the wing is increased (thus lift with small AoA) and in order to fly straight and level the nose has to be pushed way lower than with retracted flaps. You can see this in the game flying FW with flaps down and going faster than some 300 km/h.

I hope I did not make mistakes I am in a bit of a hurry.

-------------------------------------
http://people.freenet.de/hausberg/schimpf.gif

XyZspineZyX
09-04-2003, 06:23 PM
WWMaxGunz wrote:
- The question I have is: Don't the wings produce
- lift only on the basis of speed and AOA? And
- doesn't that create induced drag regardless of being
- going level or straight down? I seem to remember
- that planes that point steeply down do not fly as
- steeply downwards as they are pointed because the
- lift from the wings adds to the horizontal vector of
- the flight path. This would explain to me some,
- maybe much of why lower wingloaded planes do not
- dive as well.


If you want a 90 degrees dive, you should select an AoA that produces zero lift. That's equaly possible on high or low wingloaded aircraft. No advantage from here.


<center> http://www.stormbirds.com/images/discussion-main.jpg </center>

XyZspineZyX
09-04-2003, 08:47 PM
Issy, I have a friend with a couple of crotch rockets and I out ride him all the time./i/smilies/16x16_smiley-happy.gif After 500km he is >>finished<< [his woman less than that) but I can cruise, 2 up, at 120kph for a 1000km no problem./i/smilies/16x16_smiley-happy.gif He is also fiddling with his crotch rockets to keep them running properly while me Hog just keeps running and running and running like the battery bunny./i/smilies/16x16_smiley-happy.gif



I hope you read hop's post./i/smilies/16x16_smiley-happy.gif You sure like to twist facts./i/smilies/16x16_smiley-very-happy.gif

http://a1276.g.akamai.net/7/1276/734/625ed428e022ef/www.harley-davidson.com/PR/MOT/2004/Softail/images/DOM/img_Softail_FXST.jpg

http://www.redneckengineering.com/photogallery/photo23581/curves-done-03.jpg

"Only a dead 'chamber pot' is a good 'chamber pot'!"

XyZspineZyX
09-04-2003, 09:15 PM
FW190fan wrote:

-
-
- Eric Brown, flying a captured FW190A-4 had this to
- say:
-
- " I ascertained that the service ceiling was around
- 35,000ft." (Wings of the Luftwaffe - p.85)
-
- That's 10,000ft. above your "incontrollable at
- 25,000ft." hooey.
-
- Even charts from 1942 show the BMW801 putting out
- 1300hp at 25,000ft before higher boost pressures,
- supercharger gear ratios, and of course, GM-1 was
- made available.
-
- References of course for the FW190 flying above
- 30,000ft. on bomber intercept missions are massive.
-
- I suppose you base this stuff on the NACA bench test
- of a BMW801 in April, 1945?
-

Don't know where your '42 chart came from but a Fw '44 chart has 1000hp @ 30kft using 2700rpm and 1040hp with dynamic ram effect. At 25kft it is only 1180hp (2700rpm). At 35kft it only produced 780hp(2700rpm).

The power of the BMW801D dropped off dramatically above 20kft.

The sevice ceiling dropped from 11.5km for the A-3 to 10.5km for the A-6. The Spit V > 12.0km, IX LF > 12.96km. P-47D > 12.2km.

So some P-47s got bounced from above. Sh!t happens./i/smilies/16x16_smiley-wink.gif

http://a1276.g.akamai.net/7/1276/734/625ed428e022ef/www.harley-davidson.com/PR/MOT/2004/Softail/images/DOM/img_Softail_FXST.jpg

http://www.redneckengineering.com/photogallery/photo23581/curves-done-03.jpg

"Only a dead 'chamber pot' is a good 'chamber pot'!"

XyZspineZyX
09-04-2003, 09:31 PM
MiloMorai wrote:
- Don't know where your '42 chart came from but a Fw
- '44 chart has 1000hp @ 30kft using 2700rpm and
- 1040hp with dynamic ram effect. At 25kft it is only
- 1180hp (2700rpm). At 35kft it only produced
- 780hp(2700rpm).


what was the max boost on that engine?


<center> http://www.stormbirds.com/images/discussion-main.jpg </center>

XyZspineZyX
09-04-2003, 09:55 PM
Doesn't matter since Fw190fan said "before higher boost pressures". ie not at 1.65ata etc. '42 engines were not rated to above 1.42ata.

I took that as 1.42ata for which my numbers are for.


Huckebein_FW wrote:

-
-
- what was the max boost on that engine?
-



http://a1276.g.akamai.net/7/1276/734/625ed428e022ef/www.harley-davidson.com/PR/MOT/2004/Softail/images/DOM/img_Softail_FXST.jpg

http://www.redneckengineering.com/photogallery/photo23581/curves-done-03.jpg


"Only a dead 'chamber pot' is a good 'chamber pot'!"

XyZspineZyX
09-04-2003, 10:15 PM
MiloMorai wrote:
- Doesn't matter since Fw190fan said "before higher
- boost pressures". ie not at 1.65ata etc. '42 engines
- were not rated to above 1.42ata.
-
- I took that as 1.42ata for which my numbers are for.


You said a chart from '44. What are you trying to sell here Milo?


<center> http://www.stormbirds.com/images/discussion-main.jpg </center>

XyZspineZyX
09-04-2003, 10:25 PM
Huckebein_FW wrote:

-
- You said a chart from '44. What are you trying to
- sell here Milo?
-

Dated 11.09.44 with a signature Huckie but also on the graph it says 10.7.42./i/smilies/16x16_smiley-happy.gif

I did make a mistake and read the ps number which would make the hp numbers even lower.



http://a1276.g.akamai.net/7/1276/734/625ed428e022ef/www.harley-davidson.com/PR/MOT/2004/Softail/images/DOM/img_Softail_FXST.jpg

http://www.redneckengineering.com/photogallery/photo23581/curves-done-03.jpg


"Only a dead 'chamber pot' is a good 'chamber pot'!"

XyZspineZyX
09-04-2003, 10:34 PM
MiloMorai wrote:
-
- Huckebein_FW wrote:
-
--
-- You said a chart from '44. What are you trying to
-- sell here Milo?
--
-
- Dated 11.09.44 with a signature Huckie but also on
- the graph it says 10.7.42


So practically you wanted to mislead everybody posting data on a '42 engine and saying that it was from '44. No surprises here, we saw that before comming from you.

Try harder next time.


<center> http://www.stormbirds.com/images/discussion-main.jpg </center>

XyZspineZyX
09-04-2003, 10:42 PM
What ever you say Huckie./i/smilies/16x16_smiley-very-happy.gif

Still does change the fact the the max rpm was 2700rpm(stated) and 1.42ata(stated). If you think that is mis-leading......get a life.


http://a1276.g.akamai.net/7/1276/734/625ed428e022ef/www.harley-davidson.com/PR/MOT/2004/Softail/images/DOM/img_Softail_FXST.jpg

http://www.redneckengineering.com/photogallery/photo23581/curves-done-03.jpg


"Only a dead 'chamber pot' is a good 'chamber pot'!"

XyZspineZyX
09-04-2003, 11:03 PM
WWMaxGunz wrote:
- The question I have is: Don't the wings produce
- lift only on the basis of speed and AOA?

That is what I thought. Or at least the wings should
produce some force roughly perpendicular to the wings,
and so the force will not be lift, in the sensing
of lifting the aircraft up, but it will tend to move it.
This is the effect we see in FB just as you say.

- the flight path. This would explain to me some,
- maybe much of why lower wingloaded planes do not
- dive as well.

That's assuming that lower wingloaded planes have
good lift. It might tend to be the case, but I suggested
to SkyChimp earlier in the thread that wingloading
wouldn't be a good measure to use for this. You could
have a low wingloading, but a badly designed aerofoil
producing little lift, or maybe one in which the
lift drops off rapidly as higher speeds in the dive
are attained.

XyZspineZyX
09-04-2003, 11:06 PM
MiloMorai wrote:
- The sevice ceiling dropped from 11.5km for the A-3
- to 10.5km for the A-6. The Spit V > 12.0km, IX LF >
- 12.96km. P-47D > 12.2km.

Those figures are about 38000 ft, 35000ft, 40000ft, 43000ft,
and 40000ft. The Fw190 figures are very much more than
25000 ft even with a reduction from 190A3 to A6.

XyZspineZyX
09-04-2003, 11:10 PM
Ugly_Kid wrote:
- You might also consider continued inverted flight
- (-1g) and your wing works the other way around (not
- as effectively as right way up but it does). I make
- an educated quess but I assume that aerobatic
- aircraft probably often have symmetric profile
- (being also effective in inverted flight).

So those aerobatic aircraft would fly basically purely
by having a suitable AoA even with a symmetrical profile?
i.e. the profile is symmetrical, but the AoA is what
gives the lift? I suppose with a symmetrical profile
if you went straight down, with an AoA of zero then
this would mean that the forces on each side of the wing
would cancel? I presume that such planes have the AoA
set by the relative angles of the wings and thrust? But
in a vertical dive, the force of gravity would dominate,
so I presume that the thrust would not set the AoA,
and the wing forces would be balanced?

XyZspineZyX
09-04-2003, 11:18 PM
Aaron, send me a PM to explain what you are trying to say.


http://a1276.g.akamai.net/7/1276/734/625ed428e022ef/www.harley-davidson.com/PR/MOT/2004/Softail/images/DOM/img_Softail_FXST.jpg

http://www.redneckengineering.com/photogallery/photo23581/curves-done-03.jpg


"Only a dead 'chamber pot' is a good 'chamber pot'!"

XyZspineZyX
09-04-2003, 11:28 PM
MiloMorai wrote:
- Aaron, send me a PM to explain what you are trying
- to say.

About the AoA stuff, or the Fw190 altitudes? If it is
the latter, I was just chiming in about the suggestion
that the Fw190 was uncontrollable about 25,000 feet, and
just converting the service ceilings you posted from
metres into feet, and noting that the service ceiling
of the 190s is well over 25,000 feet.

The stuff about AoA I don't think I can explain any
better with out being able to draw or use my hands
to explain it!

XyZspineZyX
09-04-2003, 11:38 PM
FW190fan wrote:

- Unfortunately, combat was not restricted to the
- 5-7,000ft. area of high altitude where the P-47 had
- a clear advantage over the non-turbo FW190A. It was
- fought from 30,000ft all the way down to the deck.
-
- I'm of the opinion that the overwhelming majority of
- WWII combat took place BELOW 25,000ft. Even in the
- West.
-
- "Realistic combat altitude" is from sea level to
- 30,000ft, and the Thunderbolt like any other fighter
- couldn't always confine combat to the area of the
- sky where it had an advantage.

True enough. But everyone wants to compare the P-47 to their favorite German plane in dive from 1500m, or some other low altitude. Why not compare it from 25,000 feet too? I asked Huck to do that, and to date, he has not done so.



- Fact my ***, and you know it/i/smilies/16x16_smiley-very-happy.gif
-
- For example on April 29, 1943 P-47s of the 56th FG
- were flying at *28,000ft.* when they were bounced
- *from above* by FW190A-5s(possibly A-4s) of JG/26
- which quickly downed two P-47s in a quick pass.
-
-
- Eric Brown, flying a captured FW190A-4 had this to
- say:
-
- " I ascertained that the service ceiling was around
- 35,000ft." (Wings of the Luftwaffe - p.85)
-
- That's 10,000ft. above your "incontrollable at
- 25,000ft." hooey.

Big deal, what's that prove. Hell, the service ceiling of the P-39Q was 35,000 feet! Would you agree that makes IT a high altitude plane?



- Even charts from 1942 show the BMW801 putting out
- 1300hp at 25,000ft before higher boost pressures,
- supercharger gear ratios, and of course, GM-1 was
- made available.

My chart shows a little over 1,100 @ 2,700 rpm at 25,000 feet. Drops to under 1,000 at 30,000 feet.



- References of course for the FW190 flying above
- 30,000ft. on bomber intercept missions are massive.

The capability of the Fw-190A to fly and shoot at over 30,000 feet is indisputable. But please don't suggest the Fw had any sort of credible performance at this altitude. Head on into a bomber is one thing, attempting to engage fighters is another.



- I suppose you base this stuff on the NACA bench test
- of a BMW801 in April, 1945?

And I suppose you are willing to dismiss that report out of hand? There is no question the Fw-190A was a low to moderate altitude fighter. It was no high altitude plane.

And yes, there is evidence that the Fw-190 was difficult to control at high altitudes. You can reference the Fw-190 vs F4U report. Hop2002 posted another report that suggested the same thing. These probelms are almost certainly related to the "black box" on the plane.


Regards,

SkyChimp

http://members.cox.net/rowlandparks/corsairs.jpg

XyZspineZyX
09-04-2003, 11:45 PM
Huckebein_FW wrote:

- Yes any cowling around a radial engine was called
- from late 20s NACA cowling. Something really
- significant to mention about Fw-190, if you're
- looking for some trolling of course.

Yet you are quite willing to attribue any American jet innovation, and swept wing technology, or any other aeroplane contrivance to German innovation. You tried to do that with the cowling, telling Milo that the Tempest II cowling was modelled after the Fw-190A cowling. You were quick to say that, but simply can't accept it when it turns out it is the other way around.

You seem offended at the suggestion that the Americans may have developed something before the Germans.



- Also BMW-801 was an original design.

Yes, an original design using Pratt and Whitney ideas and
characterisitics. In fact, it was the Pratt and Whitney Hornet that got BMW started in the developement and production of radial engines.

Regards,

SkyChimp

http://members.cox.net/rowlandparks/corsairs.jpg

XyZspineZyX
09-04-2003, 11:53 PM
hop2002 wrote:

- Why do you find it strange that such speeds could be
- reached in a 45 deg dive? There's a lot of the use
- of the term "terminal speed" in this thread, usually
- innapropriately. Terminal speed is the maximum speed
- an object can reach. After that, it will go no
- faster. Skydivers, for example, have a terminal
- speed.
-
- Very few WW2 fighters had a terminal speed, in that
- sense. Almost all would continue accelerating until
- they broke up. Put a Mustang or Thunderbolt or
- Spitfire in a 90 deg vertical dive from altitude,
- and hold it there, and the plane will break up
- before it hits the ground.


I assume this is directed at me, since I've used the term "terminal mach" in this thread.

Hop, we can parse words if you like, but the simple fact is is that the NACA and aircraft manufacturers, as well as German test pilots used the term "terminal" speed.

I suppose technically an aircraft has no real "terminal" speed in the absolute sense.

In reality, we all here know that the when someone said a plane had a "terminal" speed of... they merely meant that the pilot dived the plane until his a$$hole puckered and decided to pull out before he died, and that noone else was brave enough to try and go faster. I understand that.


Regards,

SkyChimp

http://members.cox.net/rowlandparks/corsairs.jpg

XyZspineZyX
09-05-2003, 01:11 AM
- I assume this is directed at me, since I've used the
- term "terminal mach" in this thread.

- In reality, we all here know that the when someone
- said a plane had a "terminal" speed of... they
- merely meant that the pilot dived the plane until
- his a$$hole puckered and decided to pull out before
- he died, and that noone else was brave enough to try
- and go faster. I understand that.

It's mainly directed at Isegrim. I've also seen terminal speed used to define the maximum speed reached in many sources. I'm mainly replying to Isegrim, who thinks the fact that dives were carried out at 45 deg is evidence they were fake, as if a 90 deg dive was needed to reach high speeds.

XyZspineZyX
09-05-2003, 01:17 AM
hop2002 wrote:

- It's mainly directed at Isegrim. I've also seen
- terminal speed used to define the maximum speed
- reached in many sources. I'm mainly replying to
- Isegrim, who thinks the fact that dives were carried
- out at 45 deg is evidence they were fake, as if a 90
- deg dive was needed to reach high speeds.


Ok

Regards,

SkyChimp

http://members.cox.net/rowlandparks/corsairs.jpg


Message Edited on 09/05/0304:18AM by SkyChimp

XyZspineZyX
09-05-2003, 02:10 AM
-- References of course for the FW190 flying above
-- 30,000ft. on bomber intercept missions are massive.
-
- The capability of the Fw-190A to fly and shoot at
- over 30,000 feet is indisputable. But please don't
- suggest the Fw had any sort of credible performance
- at this altitude. Head on into a bomber is one
- thing, attempting to engage fighters is another.

And you base your affirmation on? At 30000ft max speed is still 620km/h (A8).


-- I suppose you base this stuff on the NACA bench test
-- of a BMW801 in April, 1945?
-
- And I suppose you are willing to dismiss that report
- out of hand? There is no question the Fw-190A was a
- low to moderate altitude fighter. It was no high
- altitude plane.

That was a defective unit. Do you have such reports from planes in service? otherways it doesn't prove anything beside the fact that NACA was not able to repair or correctly set-up the unit.


- And yes, there is evidence that the Fw-190 was
- difficult to control at high altitudes. You can
- reference the Fw-190 vs F4U report. Hop2002 posted
- another report that suggested the same thing. These
- probelms are almost certainly related to the "black
- box" on the plane.

That Fw-190 vs F4U raport or Fw-190 vs P-47 raport are among the most ridiculous papers ever written. You can repost them and we'll have fun on the entire weekend.


<center> http://www.stormbirds.com/images/discussion-main.jpg </center>

XyZspineZyX
09-05-2003, 02:40 AM
Huckebein_FW wrote:

- And you base your affirmation on? At 30000ft max
- speed is still 620km/h (A8).

Absolutely amazing! I suppose this is a chart for another "defective" plane:

http://members.cox.net/rowlandparks/speed.jpg



- That was a defective unit. Do you have such reports
- from planes in service? otherways it doesn't prove
- anything beside the fact that NACA was not able to
- repair or correctly set-up the unit.

Oh please. /i/smilies/16x16_smiley-very-happy.gif /i/smilies/16x16_smiley-very-happy.gif /i/smilies/16x16_smiley-very-happy.gif /i/smilies/16x16_smiley-very-happy.gif /i/smilies/16x16_smiley-very-happy.gif /i/smilies/16x16_smiley-very-happy.gif /i/smilies/16x16_smiley-very-happy.gif

You were there? You know the circumstances of it's acquisition?

Please, my sides are hurting. /i/smilies/16x16_smiley-very-happy.gif /i/smilies/16x16_smiley-very-happy.gif /i/smilies/16x16_smiley-very-happy.gif /i/smilies/16x16_smiley-very-happy.gif /i/smilies/16x16_smiley-very-happy.gif



- That Fw-190 vs F4U raport or Fw-190 vs P-47 raport
- are among the most ridiculous papers ever written.
- You can repost them and we'll have fun on the entire
- weekend.

/i/smilies/16x16_smiley-very-happy.gif /i/smilies/16x16_smiley-very-happy.gif /i/smilies/16x16_smiley-very-happy.gif /i/smilies/16x16_smiley-very-happy.gif /i/smilies/16x16_smiley-very-happy.gif of course, the German plane did not come out on top. You think anything that shows and Amewrican plane is superior is in error.



Stop with the comedy Huck, you're killin' me.

Regards,

SkyChimp

http://members.cox.net/rowlandparks/corsairs.jpg

XyZspineZyX
09-05-2003, 02:48 AM
@SkyChimp:

I think we understand one another clear enough on the FW190A at high altitude stuff. I simply took exception to the "uncontrollable at 25,000ft." stuff.

And no, I don't dismiss the NACA bench test(WRT "black box") out of hand.


@MiloMorai:

Do you know specifically why the service ceiling for the FW190A-6 is lower than for the A-3?






<center><img src= "http://www.luftwaffepics.com/LCBW4/FW190-A0-52.jpg" height=215 width=365>

<center>"We are now in a position of inferiority...There is no doubt in my mind, nor in the minds of my fighter pilots, that the FW190 is the best all-round fighter in the world today."

Sholto Douglas, 17 July 1942

XyZspineZyX
09-05-2003, 02:59 AM
SkyChimp wrote:
-
- Huckebein_FW wrote:
-
-- And you base your affirmation on? At 30000ft max
-- speed is still 620km/h (A8).
-
- Absolutely amazing! I suppose this is a chart for
- another "defective" plane:


Excellent Photoshop job Skychimp!!
Now you are forging documents, oh you really are desperate.
I save it for posterity/i/smilies/16x16_smiley-very-happy.gif /i/smilies/16x16_smiley-very-happy.gif


http://home.comcast.net/~bogdandone/fw190a8.JPG



<center> http://www.stormbirds.com/images/discussion-main.jpg </center>

Message Edited on 09/04/0309:03PM by Huckebein_FW

XyZspineZyX
09-05-2003, 03:02 AM
http://mishappa.image.pbase.com/u16/isegrim/large/5325492.Fw190A8PerformanceChartsGM12.jpg



Huckebein_FW wrote:
--- References of course for the FW190 flying above
--- 30,000ft. on bomber intercept missions are massive.
--
-- The capability of the Fw-190A to fly and shoot at
-- over 30,000 feet is indisputable. But please don't
-- suggest the Fw had any sort of credible performance
-- at this altitude. Head on into a bomber is one
-- thing, attempting to engage fighters is another.
-
- And you base your affirmation on? At 30000ft max
- speed is still 620km/h (A8).
-

620kph/i/smilies/16x16_smiley-very-happy.gif

Who is trying to mis-lead Huckie?/i/smilies/16x16_smiley-very-happy.gif From Issy's Fw190A-8 chart, only 580kph(2700rpm, 1.42ata) {360mph} and that is >>without the ETC501 fitted<< but >>with external surfaces filled and polished<<. I remember a big 'song and dance from you and Issy re. a Spitfire./i/smilies/16x16_smiley-happy.gif The u/c doors were also fitted. LOL, a specially prepeared a/c.

How many A-8s had GM1 fitted because that is the only way?


http://a1276.g.akamai.net/7/1276/734/625ed428e022ef/www.harley-davidson.com/PR/MOT/2004/Softail/images/DOM/img_Softail_FXST.jpg

http://www.redneckengineering.com/photogallery/photo23581/curves-done-03.jpg


"Only a dead 'chamber pot' is a good 'chamber pot'!"

XyZspineZyX
09-05-2003, 03:09 AM
Huckebein_FW wrote:

- Excellent Photoshop job Skychimp!!
- Now you are forging documents, oh you really are
- desperate.
- I save it for posterity

http://ubbxforums.ubi.com/infopop/emoticons/icon_biggrin.gif

You are, indeed, a "piece of work."

But by all means, save it. You obviously need it.

Regards,

SkyChimp

http://members.cox.net/rowlandparks/corsairs.jpg

XyZspineZyX
09-05-2003, 03:10 AM
MiloMorai wrote:
- Who is trying to mis-lead Huckie? From Issy's Fw190A-8
- chart, only 580kph(2700rpm, 1.42ata) {360mph} and
- that is >>without the ETC501 fitted<< but >>with
- external surfaces filled and polished<<. I remember
- a big 'song and dance from you and Issy re. a
- Spitfire The u/c doors were also fitted.
- LOL, a specially prepeared a/c.
-
- How many A-8s had GM1 fitted because that is the
- only way?

All that were supposed to do the high altitude work.


And this may come as a news to you but all the max speed tests for american or british aircrafts were made with surfaces polished. None of them were in field condition. Those that had laminar flow wings got the most important speed advantage from such polishing. Any disturbace on the laminar wing surface causes turbulent airflow and therefore the performance improvement from such wing is lost. None of the Mustangs were capable of matching factory speed specs. So what's fair for Allied aircrafts is not fair for german planes. Let's make it fair, so Milo can sleep tight tonight.



<center> http://www.stormbirds.com/images/discussion-main.jpg </center>

XyZspineZyX
09-05-2003, 03:24 AM
Huckebein_FW wrote:

-
- All that were supposed to do the high altitude work.
-

Real numbers or a percentage of A-8 a/c produced Huckie./i/smilies/16x16_smiley-happy.gif

-
- And this may come as a news to you but all the max
- speed tests for american or british aircrafts were
- made with surfaces polished. None of them were in
- field condition. Those that had laminar flow wings
- got the most important speed advantage from such
- polishing. Any disturbace on the laminar wing
- surface causes turbulent airflow and therefore the
- performance improvement from such wing is lost. None
- of the Mustangs were capable of matching factory
- speed specs. So what's fair for Allied aircrafts is
- not fair for german planes. Let's make it fair, so
- Milo can sleep tight tonight.
-

You are putting me on Huckie re. laminar wings./i/smilies/16x16_smiley-very-happy.gif /i/smilies/16x16_smiley-very-happy.gif You are not telling me something I didn't already know.

Yes, fair is fair, so next time you give speed numbers for LW a/c, be explicite about them being specially prepared./i/smilies/16x16_smiley-happy.gif No being two faced as usual.

No trouble sleepy tonight or any night Huckie.


http://a1276.g.akamai.net/7/1276/734/625ed428e022ef/www.harley-davidson.com/PR/MOT/2004/Softail/images/DOM/img_Softail_FXST.jpg

http://www.redneckengineering.com/photogallery/photo23581/curves-done-03.jpg


"Only a dead 'chamber pot' is a good 'chamber pot'!"

XyZspineZyX
09-05-2003, 03:30 AM
Looks like Issy is forging docs as well then./i/smilies/16x16_smiley-very-happy.gif /i/smilies/16x16_smiley-very-happy.gif /i/smilies/16x16_smiley-very-happy.gif /i/smilies/16x16_smiley-very-happy.gif That is were I got the graph in my post from./i/smilies/16x16_smiley-wink.gif


SkyChimp wrote:
-
- Huckebein_FW wrote:
-
-- Excellent Photoshop job Skychimp!!
-- Now you are forging documents, oh you really are
-- desperate.
-- I save it for posterity
-
- /i/smilies/16x16_smiley-very-happy.gif
-
- You are, indeed, a "piece of work."
-
- But by all means, save it. You obviously need it.
-


http://a1276.g.akamai.net/7/1276/734/625ed428e022ef/www.harley-davidson.com/PR/MOT/2004/Softail/images/DOM/img_Softail_FXST.jpg

http://www.redneckengineering.com/photogallery/photo23581/curves-done-03.jpg


"Only a dead 'chamber pot' is a good 'chamber pot'!"

XyZspineZyX
09-05-2003, 03:33 AM
Huckebein_FW wrote:

- All that were supposed to do the high altitude work.
-
-
- And this may come as a news to you but all the max
- speed tests for american or british aircrafts were
- made with surfaces polished. None of them were in
- field condition. Those that had laminar flow wings
- got the most important speed advantage from such
- polishing. Any disturbace on the laminar wing
- surface causes turbulent airflow and therefore the
- performance improvement from such wing is lost. None
- of the Mustangs were capable of matching factory
- speed specs. So what's fair for Allied aircrafts is
- not fair for german planes. Let's make it fair, so
- Milo can sleep tight tonight.


Oh, and you have proof of this? I'll expect to see some "original documents" to prove this, otherwise we'll just chock it up as another one of your absurd claims.

BTW, next time you claim that I "forge" something, you may want to know just how many graphs are avialable in that series. You "lifted" and used the one for GM-1 boost.

Again BTW, at 30,000 feet the engine control unit would have lost so much servo-oil pressure that the plane would have been difficult to control.


Regards,

SkyChimp

http://members.cox.net/rowlandparks/corsairs.jpg


Message Edited on 09/05/0306:44AM by SkyChimp

XyZspineZyX
09-05-2003, 03:41 AM
No one has answered me.

If the Spitfire was capable of diving at speeds in excess of mach .9, faster than any prop plane in WW2 (except the Tempest?) why was this tactic not universally used by the RAF? The AAF, USN, and LW all incorporated diving tactics to great advantage in WW2. Why was the LW able to escape RAF planes using the split S the entire war?

I believe hop2002 gave the excuse that is was due to slow acceleration. The Joint Fighter Conference pilots thought the Spitfires they tested accelerated rapidly in dives. Even so, after a few thousand feet the Spitfire, and all other planes, would have hit its top speed. Perhaps a few seconds later than say, a 109, but there pretty quickly. It would have overhauled the 109, or any other prop plane (except the Tempest) rather rapidly. It would at least have kept close enough to engage after pull out.

Yet, I have never read of this ever happening, the Spitfire chasing down a LW plane after a long extended dive, like Blakeslee did in the Jug after transitioning from Spitfires. Remember? It was a new, novel tactic in the ETO, an Allied plane chasing down a LW plane in a dive. Something does not compute.

So either,
1. RAF and US pilots flying the Spitfire were exceptionally stupid,
or
2. It wasn't a valid tactic.
or,
3 It was a valid and much used tactic but anecdotal evidence supporting it is missing
or
4. It couldn't really keep up with other planes in a dive
or,
5. It could keep up, but was so uncontrollable that no one dared
or,
6. US pilots were too stupid to use the tactic, thus the glee when Blakeslee out-dove the 190.

I may be missing a few.

Again, the NCAA flatly states WW2 prop design prevented mach numbers in excess of about .85. That was all you got.

Again, someone show me some sort of competitive test showing the Spitfire excelling in the dive.

We've got a chart showing massive mach numbers. Maybe the highest for any prop plane ever (except the Tempest).

We've also got a bunch of competitive tests against other planes showing the Spit to not be massive in the dive, and an entire war's set of tactics showing it was not competitive in the dive, and a Wing Leaders (Johnny Johnson) memoirs supporting the idea of the Spit being mediocre in the dive.

A chart versus what really happened. Make your own decisions.

XyZspineZyX
09-05-2003, 04:18 AM
Slickun, yet again, it was because of 'circumstances'. /i/smilies/16x16_smiley-happy.gif


Going into a high-speed, extreme-angle dive is a gutt-wrenching experience, even for the experienced. The dangers are clear, and I'm pretty sure no pilot at the seats would fully want to believe what the high offices in their comfortable research institutes back at home, behind the frontlines, would tell you via some paperwork - at least not while your life is on the line.

Therefore, unless a certain plane receives repeated recommendations on certain tactics or maneuvers, actual pilots will always be skeptical of what the real 'limit' would be - regardless of what they get to 'hear'. I'm pretty sure no pilot would think "hey, I heard from this guy back at home that our planes could do mach X during a dive safely. Maybe we should try that, too." /i/smilies/16x16_smiley-wink.gif

Also, diving out to safety, in multiple-enemy engagement situations such as in WWII, would mean that plane is out of the fight for a lengthened period of time, especially if a certain plane does not have any capability to return to the scene with recovered altitudes.

It is a last resort evasive in situations where it seems none will be able to help you in a quick notice, and thus the pilot will choose to dive away from the engagement area - which usually ensures the enemy will not follow, not necessarily because he can't, but rather he'd choose to let the diving plane go, and secure a local numbers advantage by 1 plane over the combat area - assuming equal numbers of planes met.

Following an dive-escaping enemy into low altitudes, far away from the main engagement area, is putting yourself in a state that might leave you in a one vs one situation, without any immediate help nearby, which goes for both the hunter and the hunted. Would an average pilot be so sure that he can get the enemy in a one vs one, low altitude situation, when there's no guarantee he would have better skills than the other? I think not.

Even if someone has enough experience and skills, and he is aware of it, he would not dare put himself in such a situation - as the reason that a certain pilot survives long enough to become experienced and skilled in the first place, is probably because he did not dare putting himself in an unnecessary risk at all.

Especially, in a typical situation where two sides are contending for local air-superiority, engagements between two forces would often mean reinforcements would be sent to the point of clash immediately when the situation was required to do so - chasing a diving enemy takes a long time, and the diving plane is no doubt, heading for the closest home base -> where probably reinforcements would be coming from. In the worst case, you'll get to meet hordes of enemy planes by yourself at low altitudes.

Also, as in the later days of war, when it becomes clear the 'maximum' size of forces one can muster into a single battle is so different, taking risks gets even harder for those in disadvantage of numbers. Having a prolonged fight itself was dangerous as you would have no idea how many more enemy planes are heading this way - the fight has to be short, and would need to fill only the minimum requirments of the mission, until the leader would pull off his forces and head back. Thus, there is a clear difference in behaviors and pilot aggressiveness between one side, which mission orders are to search and destroy at will, and the other, is to halt the enemy for just a while until the commanding office thinks of "Plan B".

Those circumstances should be accounted for, which IMO, has every bit as much importance on depiction of historical planes through hard-point numbers and data.





-----------
Due to pressure from the moderators, the sig returns to..

"It's the machine, not the man." - Materialist, and proud of it!

XyZspineZyX
09-05-2003, 04:23 AM
According to Neil's report, the Spitfire began to enter the dive at 39,690 feet, at an 8.6 degree angle, at mach .408. It ended at 28,820 feet at a 46.2 degree angle at mach .891.


The P-47C test started at 25,000 when it entered into a zero-lift dive at mach .84, and it ended at 21,000 feet at mach .86.

Sort of hard to say how the Spitfire would have done in the P-47's dive, and vice-versa.



Regards,

SkyChimp

http://members.cox.net/rowlandparks/corsairs.jpg

XyZspineZyX
09-05-2003, 04:49 AM
kweassa, you are agreeing that the Spitfire's massive dive wasn't used, if I'm reading your response correctly.

Due to circumstances. Fine.

Forgive me, but other forces used the dive to their advantage, in an offensive manner. They chased down the enemy A/C trying to evade them, followed by their wingman. But not the RAF.

The LW regularly ripped through formations in numbers, the whole rotte doing the one pass haul *** thing. But the RAF, able to chase them down and kill them, just held back.

Brit pilots, in dire straights, could have dove away, but didn't.....why? I don't get it.

You posted a very nice essay as to why the Brits held back the greatest edge they had....a massive dive advantage. They kept it so secret the LW never knew they had it. They didn't use it because they....what? Didn't want to?

They didn't have the guts to dive at the speeds claimed? Why not, the LW was regularly diving away, using it offensively. SOMEONE would have tried, just like Blakeslee in the Jug, and the secret would be out..HEY. We can catch those pesky LW planes.

Horse feathers, I say. If they had a dive advantage, they would have used it, being the fine pilots they were, and the LW wouldn't have punked them all war long with a split s.

If Johnny Johnson could have caught 109's in dives, I promise he would have. He was as aggressive as any US pilot, I guarantee it. Read his book. Basically, he knew the strengths of the Spit better than anyone. The dive wasn't really in his bag of tricks. Or, was he just an idiot, a bad leader not utilizing his craft to the best of his ability?

So. Forget all that. Why all the comparitive tests showing the Spit mediocre in the dive?

XyZspineZyX
09-05-2003, 04:50 AM
Skychimp, appears the Spit had no problems with dive acceleration.

XyZspineZyX
09-05-2003, 04:55 AM
SkyChimp wrote:
- Huckebein_FW wrote:
-
-- All that were supposed to do the high altitude work.
--
--
-- And this may come as a news to you but all the max
-- speed tests for american or british aircrafts were
-- made with surfaces polished. None of them were in
-- field condition. Those that had laminar flow wings
-- got the most important speed advantage from such
-- polishing. Any disturbace on the laminar wing
-- surface causes turbulent airflow and therefore the
-- performance improvement from such wing is lost. None
-- of the Mustangs were capable of matching factory
-- speed specs. So what's fair for Allied aircrafts is
-- not fair for german planes. Let's make it fair, so
-- Milo can sleep tight tonight.
-
- Oh, and you have proof of this? I'll expect to see
- some "original documents" to prove this, otherwise
- we'll just chock it up as another one of your absurd
- claims.


Of course I have, and I will use original american documents for that, not the german report on P-51B. Something you should do also. American reports on battle weary german planes, flown by inexperienced pilots and with incorrect settings are only of mild interest for a modest trolling like that of Milo.


- BTW, next time you claim that I "forge" something,
- you may want to know just how many graphs are
- avialable in that series. You "lifted" and used the
- one for GM-1 boost.


That is a forgery I have no doubt about. I'm not sure that you are the author. Did you find that in a book? I'm curious who is willing to publish such forgeries.
That is the page 17 from a report on A8. The number of the page is in the up left corner. Show us that corner and will we'll see if that is a falsified document or not. Don't forget the name of the book, otherways it means that your forged it yourself.


- Again BTW, at 30,000 feet the engine control unit
- would have lost so much servo-oil pressure that the
- plane would have been difficult to control.


Prove it with service stats, NACA did not have Fw-190 squadrons as far as I know. Bring something useful not reports on defective equipment.


<center> http://www.stormbirds.com/images/discussion-main.jpg </center>

Message Edited on 09/04/0311:02PM by Huckebein_FW

XyZspineZyX
09-05-2003, 05:20 AM
Huckebein_FW wrote:

- Of course I have, and I will use original american
- documents for that, not the german report on P-51B.
- Something you should do also. American reports on
- battle weary german planes, flown by inexperienced
- pilots and with incorrect settings are only of mild
- interest for a modest trolling like that of Milo.

Oh, but the Germans flew American planes right off the factory floor?

Now, you constantly take exception with the performance charts in AHT. So, I'll expect you to post the following reports, in their entirety, to prove your point:

1) NAS Patuxent River Flight Test Report, FT44086, January/February 1944

2) North American Aviation Report NA-46-130

Unless you can post them, and prove they were flown in the condition you claim, we'll assume you assertion is so much of your usual stuff.



- That is a forgery I have no doubt about.

Don't doubt too much. I'm about to make you look like a fool.



- I'm not
- sure that you are the author. Did you find that in a
- book? I'm curious who is willing to publish such
- forgeries.

It's funny you would ask me where I found this. YOU got that chart from Milo, I hosted it. It was hosted on my site! That's the reason I started marking charts "Courtesy by SkyChimp" because you were lifting them, without contributing anything in return! /i/smilies/16x16_smiley-very-happy.gif




- That is the page 17 from a report on A8. The number
- of the page is in the up left corner. Show us that
- corner and will we'll see if that is a falsified
- document or not. Don't forget the name of the book,
- otherways it means that your forged it yourself.

Perhaps you'll tell me the name of the book. Think hard, Huckles, Milo listed it.

Anyway, here is your proof:

http://members.cox.net/rowlandparks/chart_2.jpg



- Prove it with service stats, NACA did not have
- Fw-190 squadrons as far as I know. Bring something
- useful not reports on defective equipment.

Huck, it absolutley KILLS you that the Fw-190A was a poor high altitude performer, doesn't it. All you can do is come up with some excuse that it was defective, or the pilots were inexperienced, or some other crap. And you simply will not accept that excuse when Germans "prove" American planes had faults. You accept that as if it came from the mouth of God.



Now, Huckles. You owe me an apology for calling me a forger. Let's se if you have the guts, if you are man enough to admit you accused me wrongly.


Regards,

SkyChimp

http://members.cox.net/rowlandparks/corsairs.jpg

XyZspineZyX
09-05-2003, 05:55 AM
Slick, the 'dive speeds' we are talking about here, are pretty much near extremes. The dive is a proper and favorite tactic for many, but the comparisons quoted in this discussion by many others often relate to what would happen in a prolonged state of that dive.

It would be one thing to dive a few hundred meters to gain speed or chase an extending plane, but diving thousands of meters in a desperate escape attempt, and trying to chase that escaping plane, is something else.

The account of the LW and the RAF, each in their dire moments as you describe, would be in the early days of the war, where a Bf109E would take 4 seconds to roll just 45d bank, and the early Spitfires just as much - almost absolutely 'rock solid' - in speeds in excess of 600~650km/h.

Another thing to put into account is the famous (I'm quite surprised you didn't think of this) -G carburetor cutouts - initial stages of dive acceleration requires a push of the stick. Some say planes would roll inverted and then resume a chase, but in those planes where roll performance drops down drastically with growing speeds, such a method of chase, as I imagine, is not something that would be popular nor considered 'safe'. Thus, the first few moments of engaging in dive usually provided an acceleration advantage to the early 109s when being chased, or in need of quick response for attack - something, the RAF planes were loth to do.

The general circumstantial 'primer' concerning dives, is more of something that applies to all pilots of all countries in life-threatening combat, rather than a specific note on a certain plane - ie. pilots, will not try a high speed dive for reasons of safety and tactics - unless it is a life-threatening situation: which aqquaints with the fact that entering high/extreme speed dives were usually maneuvers of escape.

Those who successfully engage in such maneuvers, would be those who are commended and looked upon with awe as 'experts'. The planes which successfully gave confidence to its pilots in such dive performances (regardless(!) of their actual numerical data-suggested capabilities(!!)) are hence, nowadays referred to us as 'planes with great dives' - ie. the Thunderbolt.

The Spitfire, may or may not be every inch a great diver as the P-47 in reality, but how the pilots themselves might be encouraged by their plane types, is a different story. A dashing expert like J. Johnson, as you assume, probably could, and would engage in high speeds dives with excellent confidence of his plane, however, I doubt the average Spitfire pilot would be encouraged to do so, compared with the average USAAF pilots of the European theater who will immediately upon arrival of Europe, hear tales and are 'educated' by the veterans on what his plane excells in.






-----------
Due to pressure from the moderators, the sig returns to..

"It's the machine, not the man." - Materialist, and proud of it!

Message Edited on 09/05/0301:56PM by kweassa

XyZspineZyX
09-05-2003, 06:47 AM
I know that over enemy territory, I would think twice about chasing him down to the deck where it's he, me, and his sides' anti-aircraft artiller-y!

What do you do in an IL2 coop when being chased? Drag them over your airfield and let the AA chew em up!

Moral: You don't just do something because you can. At least not often.


Neal

XyZspineZyX
09-05-2003, 09:14 AM
Slickun wrote:

- If the Spitfire was capable of diving at speeds in
- excess of mach .9, faster than any prop plane in WW2
- (except the Tempest?) why was this tactic not
- universally used by the RAF? The AAF, USN, and LW
- all incorporated diving tactics to great advantage
- in WW2. Why was the LW able to escape RAF planes
- using the split S the entire war?
-
- I believe hop2002 gave the excuse that is was due to
- slow acceleration. The Joint Fighter Conference
- pilots thought the Spitfires they tested accelerated
- rapidly in dives.

The RAF's test unit, the AFDU, rated a lot of planes
as having a better initial dive acceleration than
even the Spitfire XIV, though, and the recommended
evasion tactics for Spitfire pilots did not include
diving. The Spitfire might have reached a high speed
in a long dive, but that's not going to be useful in
combat as it would mean being in danger during the slow
initial acceleration, before finally trading a lot
of combat advantage (altitude) for final separation,
leaving the plane greatly separated from its unit.


- So either,
- 1. RAF and US pilots flying the Spitfire were
- exceptionally stupid,
- or
- 2. It wasn't a valid tactic.

I'd go for 2. The AFDU recommended tactic was to
use the superior turn in the Spitfire as far as I
remember. (And conversely, due to the poor turn in
the Tempest, it was recommended that the Tempest NOT
use turn, hence Spitfire units were not to be transferred
onto Tempests).


- it was not competitive in the dive, and a Wing
- Leaders (Johnny Johnson) memoirs supporting the idea
- of the Spit being mediocre in the dive.

It probably depends on the length of dive, the figures
that Neil posted showed something like 8000 feet or more
required to reach Mach 0.89. That's going to put you
2 to 3 miles away from your squadron horizontally, and
1.5 miles vertically. That would put you in a vulnerable
position, potentially.

XyZspineZyX
09-05-2003, 09:26 AM
Slickun wrote:
- kweassa, you are agreeing that the Spitfire's
- massive dive wasn't used, if I'm reading your
- response correctly.
-
- Due to circumstances. Fine.
-
- Forgive me, but other forces used the dive to their
- advantage, in an offensive manner. They chased down
- the enemy A/C trying to evade them, followed by
- their wingman. But not the RAF.

The AFDU recommended other forms of maneouver for
Spitfires as forms of evasion. These other forms
(essentially using turn) would mean that the Spitfire
would bleed some speed, but would remain at the altitude
of the engagement, and not be removed from the fight.
This is better for the squadron as a whole, as they
are then not (even temporarily) a man down. Also note
that the Spitfire can't initially confidently outdive
the 190 or 109. So a short dive (which removes the Spit
from the fight for a lesser period of time) doesn't
initially improve the situation for the Spitfire. In
other words, the Spit can only improve its situation
individually (assuming no other fighters at lower alt
pounce on it) if it goes into an extended dive, which
harms the squadron more.

If you look at slower turning planes such as the Tempest,
using turn as evasion is not an option.

When it is an option, though, evading at the same alt
as the squadron is best for the squadron, plus it means
not leaving your plane exposed by separating it from the
squadron. In short, if you can evade without diving, it
makes more sense to do that.

- The LW regularly ripped through formations in
- numbers, the whole rotte doing the one pass haul ***
- thing. But the RAF, able to chase them down and
- kill them, just held back.

If the RAF squadrons were en route to a target, or
engaged in escort, etc., then there would be no advantage
in them following the LW planes unless they had planes
to spare for that purpose. Also if you are flying into
enemy territory, then going lower puts you at risk of
being bounced by LW top cover.

From the LW's point of view having altitude is doubly
advantageous. They can send a unit through in one pass,
taking down some RAF planes. If the RAF engages, it
reduces its strength at altitude, removing its own
tactical advantage. It also puts the units diving into
the situation that if they engage and slow down, reducing
their ability to zoom back up, they become vulnerable to
being bounced in turn. The RAF units are also split up
and individually more vulnerable.

The RAF are in a very difficult position, however. If they
do not engage it damages morale. If they do engage, even
if they can catch the attackers, they reduce the tactical
strength of their unit by divding it, and risk being bounced.

If you are the attacker, the mass dive bounce punching
through a formation, if you have weaponry sufficient
to down planes on a single fleeting engagement (e.g.
4 20mm cannon on the Fe190, Tempest, etc) then its
a great tactic to use.

XyZspineZyX
09-05-2003, 09:37 AM
WWMaxGunz wrote:
- I know that over enemy territory, I would think
- twice about chasing him down to the deck where it's
- he, me, and his sides' anti-aircraft artiller-y!
-
- What do you do in an IL2 coop when being chased?
- Drag them over your airfield and let the AA chew em
- up!
-
- Moral: You don't just do something because you can.
- At least not often.

True - in IL2/FB coops and df I try to always grab
altitude if I can. If I am separated from my unit, I
grab altitude. You need to be pretty sure what is going
on below before you dive to engage. Of course I also
get bored with BnZ after a while and start tangling in
TnB, which tends to be the point I get shot down. Basically
I am not happy even in a DF server until I am at 5000m.
It means I probably engage less than many, but that's
what happens. 5000m isn't really high, but seems to be
relatively high in a DF server.

Having alt allows you to bounce more safely, and also
run away to your home base more easily! In one Iron Skies
scenario, after the flight I was with got decimated (it
was mostly an AI unit anyway).

I dove half way across the map from 20,000 feet to home
base, about 550kph most of the way. The LW were deriding
me all the way, of course, but I made it back in one
piece.

XyZspineZyX
09-05-2003, 12:09 PM
Wonderful explanations, well thought out, explaning why an entire generation of RAF pilots failed to use a massivve advantage they had over enemy planes.

Horsefeathers. If the Spitfire was so great in a dive, as the chart suggests, it would have been used.

Later versions did not have a problem with carburator cutout.

A German plane, in a turning fight, with the Spitfire gaining on him, simply did a quarter roll and left the fight. So, even with the Spitfire having a massive dive advantage, let the FW go? Every time? There would be no carburator cutout.

After a few thousand feet the Spit would gain rapidly. building up massive E. This is what happened with US planes. The LW bounced them, headed down. The US planes gave chase. Big lead at first, but the US plane hauled them in.

Why didn't the RAF use the Spitfire as a huge bounce and zoom plane? The AAF used the P-47 that way. Fly in a big altitudes, dive down with a massive speed, one pass, head back up.

Instead, as the above posters have shown us, the type flew along trying to engage in turning fights. The dive just wasn't a part of the package. Not recommended. Neither in defense, nor offense.

Johnson didn't use the dive because the Spitfire, in his opinion, wasnt' good at it. Not because the other guys in his squadron were timid. Not because of what others recommended as tactics.

Abilities dictate tacitcs, my friends. Not the other way around. The Brits were smart enough to recommend dives in the Tempest.

So. How come no comparison tests show the Spitfire other than mediocre in the dive? Why never a line "slow initially, but in extended dives pulls away?" I've read that description about other planes in British tests.

"Spitfire as the greatest diving plane" advocates are slowly painting yourselves into a corner. We have agreed the dive wasn't used as a tactic.


You have set forth that it was so poor in initial acceleration that the massive top end couldn't be used.


I guess what you are left with is that the Spitfire was so poor in initial acceleration that the dive was useless as a tactic, but in a long, long, extended dive it sloooowly accelerated until it exceeded mach .9? Faster than any other prop plane, maybe EVER?

Anyway, all the posters on here are smart enough to form their own conclusions.

XyZspineZyX
09-05-2003, 12:16 PM
Look at Neils chart. It takes a lot of air for the Spit to get to mach .8, but most of the early dive is at a shallow angle. Once it hits steeper angles the type seems to accelerate well enough to me. And remember, once mach .8 was attained the Spit would no longer be losing ground.

Massive TAS is maintained for many, many thousands of feet.

There it is. Posted. A chart showing the best dive characteristics of the war. Yet, as the above posters have fought very hard to show, the dive was not used.

Draw your own conclusions.

XyZspineZyX
09-05-2003, 12:54 PM
woops, - nt.

Message Edited on 09/05/0308:58PM by kweassa

XyZspineZyX
09-05-2003, 12:58 PM
"Horsefeathers. If the Spitfire was so great in a dive, as the chart suggests, it would have been used."

No doubt, the Spitfire would have used it if the conditions allowed him to. Over a friendly territory, or if somehow an experienced pilot would sense the enemy is trying a simple Split-S with a bit wider radius than normal to momentarily ensure safety, the Spitfire would follow. The general idea me, and Aaron it seems as well, is trying to suggest is that it wasn't necessarily an "OK, Spitfire pilots, don't dive and don't chase" agenda.

It was a case-by-case matter, and usually during a typical combat, the case wasn't present enough to offer an opportunity to fully chase an enemy aircraft, with no idea of how long the chase might last or what conditions a pilot might meet - especially if the operating fighters were severly range limited compared to those fighting on their home ground, or those of the USAAF which would fly long and far.

...

"A German plane, in a turning fight, with the Spitfire gaining on him, simply did a quarter roll and left the fight. So, even with the Spitfire having a massive dive advantage, let the FW go? Every time? There would be no carburator cutout"

But try to move away from the 1:1 mentality. Imagine it wasn't a single Spit vs a single Fw190, but a 4xFw190As meeting 4xSpitfireMkIXs at simular altitudes. For some reason, a problem in communications has left a single Fw190 alone, without any protection from his wingman, and a Spit latches behind.

The Fw190 searches for help, but his 3 friends are tied up with other 3 Spits. He chooses to try a long dive as a despeatae attempt to escape.

Now, in that situation, as an individual seeking kills, the Spit could, and probably would try and follow the Fw190. But think of it in the team aspect - you are not free to just larry off and chase someone freely. The most reasonable course of action would be to let the Fw190 go, and join your wingies, which would present a 3 vs 4 situation, and secure a local tactical advantage which can prove very vital for all of your flight(!).

Thus, the situation dictates the course of your actions, and whether you could, or could not do something, as pointed out by someone else, is irrelevant.

...

"Why didn't the RAF use the Spitfire as a huge bounce and zoom plane? The AAF used the P-47 that way. Fly in a big altitudes, dive down with a massive speed, one pass, head back up."

There are many reasons one can think of, and among them are that Spitfires weren't as good as the USAAF planes in the hunter/killer role.

The limitations came from a simple fact: that they cannot fly for long. The Spitfire is very much concentrated at an interceptor role, which provides a point-advantage at a certain tactical location, whereas USAAF planes were relocated to long-range escort duties first, and then would sweep large areas of the German territory to draw out nemy fighters in the latter phases of the war. Getting to alt, fighting enemies, clearing the skies, then getting to alt again, and searching some more.. this, takes a long time, and time which the Spitfires have not.

Also, we have a bad tendency to overlook a certain planes' attributes in maneuverability - ie. referred to as "yank and bank" or "turn and burn". Gamers have a tendency to think planes that have superior maneuverabilities are for low-level type of combat, and the experts would much prefer faster planes referred to as "energy planes".

However, a plane like a Spitfire doesn't necessarily need an altitude advantage to secure a tactical advantage. It is those planes that cannot secure an advantage on equal terms, that need altitude advantage, and would rely on group tactics comprised of dives and zooms.

Simply put, the RAF didn't use the Spitfires as "a huge bounce and zoom plane", because Spitfires didn't really need to use the specific tactic to secure an advantage. They wouldn't necessary shy away from the "BnZ" tactic, but there was no need to absolutely emphasize it, as the conventional method of dogfighting was enough to corner German planes. Why resort in a more complicated method, when the more simple one can easily give you an advantage enough?

.......

"Abilities dictate tacitcs, my friends. Not the other way around. The Brits were smart enough to recommend dives in the Tempest."

Tactics, solely rely on situations. According to situations, a certainly 'ability' may not mean anything at all, even(!). Even if the Spitfire can dive, it usually will not need to, or would not have a chance to. But if someone was in a panic to escape, it's not like the pilot would not try it at all at such scircumstances.


.....

"I guess what you are left with is that the Spitfire was so poor in initial acceleration that the dive was useless as a tactic, but in a long, long, extended dive it sloooowly accelerated until it exceeded mach .9? Faster than any other prop plane, maybe EVER?"

What we are suggesting, is not as you understand it. Isegrim has pointed it out properly, albeit with a strong and hostile tone - the mach number reached with the Spitfire is more than meaningless as the plane broke up, pilot fainted, and test conditions are 'bizzare'.

The performance of the Spitfire in pretty much irrelevant at best, as the tactical conditions did not require the Spitfire into entering one. If anyone had to dive away, it was usually the Germans, not the Spitfires. Whether the Spitfire would choose to chase him or not, would also depend on his current tactical position of battle.


-----------
Due to pressure from the moderators, the sig returns to..

"It's the machine, not the man." - Materialist, and proud of it!

-----------
Due to pressure from the moderators, the sig returns to..

"It's the machine, not the man." - Materialist, and proud of it!

XyZspineZyX
09-05-2003, 03:00 PM
- What we are suggesting, is not as you understand
- it. Isegrim has pointed it out properly, albeit with
- a strong and hostile tone - the mach number reached
- with the Spitfire is more than meaningless as the
- plane broke up, pilot fainted, and test conditions
- are 'bizzare'.

Speeds greater than mach 0.9 are refering to calculations of what happened to a Spit pilot who blacked out at very high altitude, went in to a power dive, and then recovered. That wasn't propoerly instrumented, and is hardly reliable. The Spit did not break up.

The test results Neil Sterling posted are from fully instrumented tests in to high speed flight. The Spitfires involved did not crash. Indeed, if you look at the details of Neil's charts, you will see several dives were involved.
I have seen no indication any of these tests resulted in crashes.

The reference to a crash that Isegrim is "quoting" is a seperate, later series of tests, in which one of the planes suffered a failure of the propeller reduction gear at high mach number, causing the prop to shear away, and the plane catch fire.

In fact, if you look at one of the charts Neil posted, "Spitfire - Typical High Speed Dive", you will see that by 20,000ft the plane had recovered.

XyZspineZyX
09-05-2003, 03:02 PM
Duly noted.

Thanks for the correction, hop2002.



-----------
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XyZspineZyX
09-05-2003, 03:28 PM
Slickun, you are asking some good questions. I agree many of the answers here are not completely satisfactory, so I will try to just point a few things out:

Slickun wrote:
- No one has answered me.
-
- If the Spitfire was capable of diving at speeds in
- excess of mach .9, faster than any prop plane in WW2
- (except the Tempest?) why was this tactic not
- universally used by the RAF?

The tests posted by Neil do not state it will dive at speeds in excess of Mach 0.9. The highest speed achieved in that test was 0.89. This may seem like semantics, but due to the very steep drag rise past the drag divergence Mach number, a difference in the order of 1% is significant.

There was some mention here of an Aeroplane magazine article that stated higher speeds (the number I remember was 0.96 from that report). Those speeds are regarded as unlikely by most in the aerospace community - but notice it is much higher than the 0.89 shown in the test posted by Neil. The test posted here (with the 0.89 claim) was done under controlled conditions with proper instrumentation and compressibility corrections. Today we have better telemetry, but for the 1940's technology that is basically as good as it gets and even today it would be regarded as a good test as long as the instruments were properly calibrated.

The dive that shows the 0.89 number in the test was performed from 40,000 feet. This brings us to one of the reasons why this type of speed was not repeated everyday in combat. Here is a short summary of how speed of sound and density changes with altitude. I will use English units as most of the speeds mentioned here were in mph and altitude in ft:
alt [ft] -- speed of sound [mph] -- density [slugs/ft^3]
10,000 -- 735 -- 1.756e-3
20,000 -- 707 -- 1.267e-4
30,000 -- 678 -- 8.907e-4
40,000 -- 660 -- 5.873e-4

So, by testing at very high altitudes (for the period), you have low speed of sound, and low density. This means that for a high Mach number, a lower true air speed is required, and an even lower dynamic pressure is experienced by the aircraft due to the low air density. High Mach speed tests are therefore much less stressful on the aircraft at high altitudes, and they are easier to achieve. Note that 0.89 Mach was achieved at 29,000 feet, still a very high altitude (for a WWII fighter). Someone was asking why the dive was not performed in the vertical, and this is one of the reasons - so you can stay at higher altitudes for longer. Being able to achieve 0.89 Mach in a dive from 40,000 feet does not mean the same will be possible from, for example, 20,000 feet.

The important thing to keep in mind here is that a test like this is carefully planned. It is not the type of thing that can quickly be reproduced by a pilot in combat. If this combat is taking place at somewhere between 20,000 and 30,000 feet, it is most likely physically impossible to repeat that Mach number.

Slickun wrote:
- Yet, I have never read of this ever happening, the
- Spitfire chasing down a LW plane after a long
- extended dive, like Blakeslee did in the Jug after

The tests show a high maximum Mach number - that is all. For an aircraft to have a marked advantage in the dive, this is not enough. Acceleration in the early stages of the dive is probably one of the most important features, since this happens while the two aircraft are still close together. The Spitfire was not the most efficient aircraft out there in high speed level flight or at speeds up to the point where compressibility becomes important (it was not bad either - but some aircraft were more efficient). It would require very special circumstances for the Spitfire to be in a position to use its high drag divergence Mach number to its advantage. Once again, the special type of test shown here is not something that can just be quickly repeated on a whim during combat.

Slickun wrote:
- Again, the NCAA flatly states WW2 prop design
- prevented mach numbers in excess of about .85. That
- was all you got.

I see this often repeated with different Mach numbers (.85 is the lowest I have seen yet). Do you have a cite for this, a NACA report number or similar for instance? I would be very interested in reading it. You may be familiar with some of the early development on supersonic propellers - the problem was tip speeds in excess of around 0.9 Mach, depending on the airfoil used on the propeller, that caused a large drop in efficiency on existing props. But this research was aimed at pushing propeller driven aircraft closer to sonic speeds in level flight. I have not seen studies that dealt with ultimate Mach limits in the dive, so once again, if you have a cite I would appreciate it.

Regards,
Oryx

XyZspineZyX
09-05-2003, 04:27 PM
OK. We all seem to agree. The Spitfire was not good enough in the dive to consider using it in any sort of "normal" combat situation.

I'm sorry, but I refuse to believe the RAF would refuse to advocate the tactic, and all its ramifications, if it was capable. I just have too much respect for the RAF and its pilots to even entertain the notion they refused to avail themselves of this, that for the entire war they just failed to finish combats, chase an enemy, or use bounce tactics, if they had been capable.

One thing the LW always counted on from a Brit, they would engage. They would NOT refuse a combat. They felt the Brits were always good for a fight, just as they thought the #1 quality of the US pilots was extreme agression, often to a fault. I just can't accept the Brits just "sat" on great dive performance.

As I've posted, everyone can make their own conclusions.
Mine is that the Spitfire dove like the comparitive tests showed, mediocre.

It is possible to chase an enemy plane down in a dive, the AAF did it all the time. Remember this, gentlemen. It was not unheard of, or even rare, for the AAF Mustangs and Thunderbolts to scream down after a LW plane. The folks above painting that as a dubious or ill advised tactic are misinformed. It was possible, even probable, that the chaser brought his wingman with him, or even half a squadron. It would be easier to maintain integrity in a dive than a turn fight. The AAF planes were capable of doing it. I don't think the Spitfire was.

So, we are left with the chart. The Spitfire accelerated so slowly in a dive the tactic was useless in air to air combat, yet after a long long while it exceeded every other prop planes mach numbers. That seems to be the concensus.


Please, Guys. hop2002 has schooled me EXTREMELY well in mach numbers, divergent mach numbers, indicated air speeds and such. I don't need another lesson. This ain't my first rodeo. :-)

Oryx, as I posted before, I can't locate the NACA study. I apologize, and I know citing it without showing it is chicken$hit. Apologies. I swear, I have seen and read it, and think I dl it once.

I do have the locations of studies the NACA did on propellor design to exceede this limit. These studies kind of allude to the other. With high tech prop design the XP-88 got to mach .93. I'll be home tonight and post the link.

Of course, I meant the Spitfire exceeded mach .89, not .9. Thanks for pointing it out.

XyZspineZyX
09-05-2003, 04:53 PM
Look, fellas. I don't want to engage in Spitfire bashing. I don't even want to get into numbers. I guarantee nearly all the posters on this thread are better at math and aerodynamic theory than I am.

I'm trying to talk about realities. What actually happened? Not a soul has questioned my assertion that the Spitfire did not use diving tactics regularly, either defensively or offensively.

The tactics were possible, the AAF used them all the time, trained in them, and destroyed enemy A/C with regularity using diving tactics.

The LW used them the entire war to escape Spitfires. We all seem to agree on that.

The above are examples of the dive used both offensively and defensively. Everybody else used them, why not the RAF in the ETO? They used dive and zoom tactics in the PTO, over Australia, against the A6M's of Japan. Saying they could have used the tactics in the ETO, but held back for some reason, just doesn't hold up.

As I've said, we can all draw our own conclusions. It seems to be that the Spit accelerated very slowly in a dive, so slowly it wasn't a valid combat tactic, but just kept trucking until it could attain mach .89, a higher recorded number than any other prop plane in WW2.

Or, are we claiming a higher number for the Tempest?

Edited to remove an unnecessary "1" after Tempest.




Message Edited on 09/05/0305:57PM by Slickun

XyZspineZyX
09-05-2003, 05:35 PM
hop2002 wrote:
-
- It's mainly directed at Isegrim. I've also seen
- terminal speed used to define the maximum speed
- reached in many sources.

Sorry Hop, but I afraid that your terminal speed idea is a bit out of the world of reality. It`s simply impossible for a given design aircraft to just keep accelerating above a certain Mach number. Drag prevents it after a while, especially from the prop. This was shown in dozens of tests (Yeager...), and I won`t even start an arguement on that, just like I really don`t see any sense in arguing with someone who would state that the Earth is flat. Even though it might reach higher TAS in a dive as it get lower and lower, it will never go beyond a certain Mach number. And the latter is all crucial in terms of aerodynamics, the TAS is merely a maximum absolute airspeed. When referring to "terminal speed", I bet everyone ment "highest attainable Mach number", though for obvious considerations it become a bit unclear.

-
- I'm mainly replying to
- Isegrim, who thinks the fact that dives were carried
- out at 45 deg is evidence they were fake, as if a 90
- deg dive was needed to reach high speeds.
-

Basic physics, Hop. I already listed why the Spit was in pretty much every regard bad for dives. It`s high drag design. It has low weight. Low wingloading. It has serious turbulance sources in both the fusalge (windscreen, engine humps) and wings (radiators and gun barrels). It doesn`t have any little swept in the wings.
As far you "thinnest wing than on any major ww2 fighter" - sorry, it`s hype. I have never seen anything that would support it, but even looking on drawings shows that it has absolutely ordinary, not at all thin wings. Maybe it was considered thin in 1935. It wasn`t thin compared to later ones. Anyway, irrevelant.

The claim that the 45 degree dive is a hype is easy to understand, if you compare it to other tests, which were done at steep (70-90degree) dive angles, where added counterforce against the dive was much lower, as there was only minimum lift developed. Then, the Brits come out and say that their plane can outdive heavier, cleaner, higher wingloading designs at HALF the dive angle, at least that`s what they have on paper, regardless that in all empirical tests the Spit took the low end of the stick.

Sorry, it`s like as if someone would state that a Mini Morris, despite being inferior in horsepower, traction, max. speed etc. to an Aston Martin can actually beat the latter in long races... just because someone actually failed to set that speedometer right. Or just didn`t want to make it right in the first place.

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XyZspineZyX
09-05-2003, 05:40 PM
MiloMorai wrote:
-
-
-
- From Issy's Fw190A-8
- chart, only 580kph(2700rpm, 1.42ata) {360mph} and
- that is >>without the ETC501 fitted<<

Yep, about 580 kph. The ETC should kill about 10-15 kph speed, still 565kph, comparable or superior to the majority of fighters in 1944.


- but >>with
- external surfaces filled and polished<<.

Which means it represented an a/c in good condition, nothing special again. Very different from Hop`s pet XIV which run overboosted, half load (95% TO weight), aerials, wingtips, rear view mirror etc. stripped from it, in addition from getting a new paint job and was rubbed down carefully.


- The u/c doors were also fitted.
- LOL, a specially prepeared a/c.

Special? What was special about u/c doors? All FW 190 had them as standard.

-
- How many A-8s had GM1 fitted because that is the
- only way?
-

100% . All were capable using it. It was a matter of choice, wheter to load up C-3 fuel or NO2 in the tank.

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XyZspineZyX
09-05-2003, 06:15 PM
Vo101_Isegrim wrote:
- As far you "thinnest wing than on any major ww2
- fighter" - sorry, it`s hype. I have never seen
- anything that would support it, but even looking on
- drawings shows that it has absolutely ordinary, not
- at all thin wings. Maybe it was considered thin in
- 1935. It wasn`t thin compared to later ones.
- Anyway, irrevelant.

Are you sure about this? Here is what I have for airfoil thicknesses at the root and tip:
Spitfire: 13% (root) 9.4% (tip)
Bf-109 A-E: 14.2% (root) 11% (tip)
Bf-109 F-K: 14.2% (root) 11.35% (tip)
Fw190: 15.3% (root) 9% (tip)
*P-51: 15.1% (root) 11.42% (tip)
P-47: 15% (root) 15% (tip)

*I have a conflicting source for the P-51 that lists a thicker airfoil at the root, but I think the 15.1% value is the correct one.

And thickness is certainly not "irrelevant" when talking about compressibility effects.

Message Edited on 09/05/0308:16PM by Oryx

XyZspineZyX
09-05-2003, 06:35 PM
Vo101_Isegrim wrote:
-
- MiloMorai wrote:
--
--
--
-- From Issy's Fw190A-8
-- chart, only 580kph(2700rpm, 1.42ata) {360mph} and
-- that is >>without the ETC501 fitted<<
-
- Yep, about 580 kph. The ETC should kill about 10-15
- kph speed, still 565kph, comparable or superior to
- the majority of fighters in 1944.
-

Superior to such a/c as, Issy? That speed(360mph/351mph) is for 30,000ft. Don't read the posts or the graphs very well? It says 12 to 16kph loss for the ETC501./i/smilies/16x16_smiley-happy.gif Slight, but typical, deception on your part./i/smilies/16x16_smiley-happy.gif

-
-- but >>with
-- external surfaces filled and polished<<.
-
- Which means it represented an a/c in good condition,
- nothing special again. Very different from Hop`s pet
- XIV which run overboosted, half load (95% TO
- weight), aerials, wingtips, rear view mirror etc.
- stripped from it, in addition from getting a new
- paint job and was rubbed down carefully.
-

Ah, the double standard./i/smilies/16x16_smiley-very-happy.gif It means specially prepared - extra care taken to obtain max performance. Elaberate on 1/2 load. No not any different than you claim for the Spit.

-
-- The u/c doors were also fitted.
-- LOL, a specially prepeared a/c.
-
- Special? What was special about u/c doors? All FW
- 190 had them as standard.
-

No they were NOT. When the ETC was fitted the inner u/c doors were removed - had to be./i/smilies/16x16_smiley-happy.gif /i/smilies/16x16_smiley-happy.gif That is the doors that were fitted./i/smilies/16x16_smiley-happy.gif

--
-- How many A-8s had GM1 fitted because that is the
-- only way?
--
-
- 100% . All were capable using it. It was a matter of
- choice, wheter to load up C-3 fuel or NO2 in the
- tank.
-
-

The high performance 801s were in short supply. I can see your answer, so give production numbers.


Why are you answering when the post was directed to Huckie?


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XyZspineZyX
09-05-2003, 06:43 PM
I am speaking in absolute terms, not relative ones. At the root the spit had about 35 cm thick wing, while 109s typically about 27cm... others are similiar as well, below 30cm.

You speak of thickness ratios, relative to wing depth, but those alone dont tell much about the airfoil itself, how much it "bends" and that the airfoils that try to make up for their absolute thickness with depth also penelize themselves with turbulance due to surface inperfections (rivets, bulges, which the Spit wing has in very generous numbers) to a large extent. The simpliest example is the P-51s laminar flow wings vs. the Spits. I don`t think anybody would claim that the Spit`s wing design was actually better than the P-51s against compressibility effects... especially as it is PROVEN by tests that compressibility effects come early on Spits, but rather late on P-51s. See the NACA tests SC has reffered to. Sorry to say that, but again I see that it`s a hype ("thin wings explains it all") is supposed to prove another hype ("Spitfire, the highest Mach number reaching fighter of WW2"), again.



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Message Edited on 09/05/0307:45PM by Vo101_Isegrim

XyZspineZyX
09-05-2003, 07:00 PM
Using C3 or GM-1 was not a matter of choice at all...
No A-8 could take GM-1 since they were not equipped with the insulated tank but with the dual use (fuel/MW-50) light alloy tank.

GM-1 use was dropped altogether in most aircraft by mid 1944 when appeared clearly that the engagement altitude where below the minimum altitude of GM-1 use. This led to the reconversion of a number of 109 which previously used GM-1 to MW-50 use.


Butch

XyZspineZyX
09-05-2003, 07:03 PM
As if the 109 had perfect wings - bulges for the wheels, span wise openings for the radiator flaps(wing top), flaps, slats all causing turbulance. Never mind the less than perfect constuction due to the use of "slave labour".

A 10% airfoil bends less than a 15% airfoil. The % is the % thickness in relation to the airfoil length.



Ah, thanks very much for the GM1 info Butch./i/smilies/16x16_smiley-happy.gif

"Using C3 or GM-1 was not a matter of choice at all...
No A-8 could take GM-1 since they were not equipped with the insulated tank but with the dual use (fuel/MW-50) light alloy tank.

GM-1 use was dropped altogether in most aircraft by mid 1944 when appeared clearly that the engagement altitude where below the minimum altitude of GM-1 use. This led to the reconversion of a number of 109 which previously used GM-1 to MW-50 use.


Butch"

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"Only a dead 'chamber pot' is a good 'chamber pot'!"

Message Edited on 09/05/0302:04PM by MiloMorai

XyZspineZyX
09-05-2003, 07:07 PM
butch2k wrote:
- Using C3 or GM-1 was not a matter of choice at
- all...
- No A-8 could take GM-1 since they were not equipped
- with the insulated tank but with the dual use
- (fuel/MW-50) light alloy tank.
-

Butch, the series of A-8 tests show the use of GM-1. They also show the possible use of GM-1 AND C-3 injection at the same time. IIRC we had a discussion about this a good while ago, and you even said after looking some docs up, that it was indeed possible.


- GM-1 use was dropped altogether in most aircraft by
- mid 1944 when appeared clearly that the engagement
- altitude where below the minimum altitude of GM-1
- use. This led to the reconversion of a number of 109
- which previously used GM-1 to MW-50 use.

But this applies to 109s only, isn`t it? Their rated alt. was considerably higher, 7-8km, than the 190A`s 5.5-6.3km. The GM-1 use with the 190s lower rated alt. seems to be much less of a problem, the doc shows it at 8km already, which was not uncommon on the Western front.

http://vo101isegrim.piranho.com/FB-desktopweb.jpg
'Only a dead Indianer is a good Indianer!'

Vezérünk a Bátorság, K*sérµnk a Szerencse!
(Courage leads, Luck escorts us! - Historical motto of the 101st Puma Fighter Regiment)

Flight tests and other aviation performance data: http://www.pbase.com/isegrim

XyZspineZyX
09-05-2003, 07:14 PM
MiloMorai wrote:
- As if the 109 had perfect wings - bulges for the
- wheels,

Yep, 1-1 bulges on each wing top. That`s 2.
.
Spitfire: 1-1 bulges for wheels, plus 2x2-2x2 bulges for Hispanos, + 1-1 bulges for Brownings.

That`s 12...


- span wise openings for the radiator
- flaps(wing top),

LOL, what the hell does it matters if it`s on the trailing edge, and does not open above wing level in high speed flight anyway? How desperate...

- flaps, slats all causing
- turbulance.

LOL, flaps on the TRAILING EDGE also cause turbulance - according to Milo.

Slat causing turbulance? No more than the fitting of the leading edge to the main spar on any other fighter.
Funny, all the supersonic F-1x series have slats... interesting. Must be bad, because Milo says so.

- Never mind the less than perfect
- constuction due to the use of "slave labour".

Show me a picture of "slave labour" used in 109 wing construction.... Oh, thing made up again.

-
- A 10% airfoil bends less than a 15% airfoil. The %
- is the % thickness in relation to the airfoil
- length.
-

Completely false. % airfoil thickness does not gives any information on airfoil bending. Again, P-51 wings are best example.




http://vo101isegrim.piranho.com/FB-desktopweb.jpg
'Only a dead Indianer is a good Indianer!'

Vezérünk a Bátorság, K*sérµnk a Szerencse!
(Courage leads, Luck escorts us! - Historical motto of the 101st Puma Fighter Regiment)

Flight tests and other aviation performance data: http://www.pbase.com/isegrim

XyZspineZyX
09-05-2003, 07:17 PM
- Sorry Hop, but I afraid that your terminal speed
- idea is a bit out of the world of reality. It`s
- simply impossible for a given design aircraft to
- just keep accelerating above a certain Mach number.

I said it would keep accelerating until it broke up. WW2 fighters could not be put in to a full power vertical dive from high altitude and held there, they would simply break up. That's why pilot's notes give never-exceed speeds.

For example, the P-51D manual gives a max permissible dive speed of 340 IAS at 28,000ft. Not "go as fast as you can", but don't go beyond 340 IAS.

You have to have a very strong, low powered, high drag fighter to simply hit a "terminal speed" that won't allow you to go faster, and won't destroy the plane.

- Even
- though it might reach higher TAS in a dive as it get
- lower and lower, it will never go beyond a certain
- Mach number.

No, it will break up. Look at it this way, to reach a terminal speed, drag = thrust. In a full power vertical dive, you have the plane's normal thrust, plus gravity. For a Spit or 109, that means total drag reaches 7 - 10,000lbs. These planes weren't built to withstand that sort of force, not combined with the turbulence that occurs at high mach numbers. For comparison, at around 400 mph in level flight, these planes expierenced what, around 1,000 lbs of drag? Something in that range, and without the turbulence you get at very high speed as well.

- Even
- though it might reach higher TAS in a dive as it get
- lower and lower, it will never go beyond a certain
- Mach number. And the latter is all crucial in terms
- of aerodynamics, the TAS is merely a maximum
- absolute airspeed

TAS doesn't matter much in aerodynamics, but mach is not the only thing that matters, IAS matters as well. You can be safely within your mach limit, and still break up because IAS is too high. The Spit, Mustang etc could all do more than mach 0.8, but not at low level. 0.8 at low level is around 600 IAS, and I can assure you any Spit or Mustang trying to do 600 IAS at low level isn't going to last long.

- When referring to "terminal
- speed", I bet everyone ment "highest attainable Mach
- number", though for obvious considerations it become
- a bit unclear.

And I was simply trying to make it clear. Terminal speed means different things to different people, I was just clarifying, in light of your claim that the highest attainable speed could only be attained in a 90 deg dive.

- Basic physics, Hop. I already listed why the Spit
- was in pretty much every regard bad for dives. It`s
- high drag design.

High drag at what speed?

Look at Neils chart. It shows the Spit at .0225 or so at lower speeds. By mach 0.85, it's up to .036 or so. That's what critical mach, or drag divergent mach speed, refers to. It's the much higher drag you experience when the airflow begins to compress and becomes turbulent.

A plane can easily have higher drag at low speeds, and lower drag at high speeds, if it has a higher critical mach. The main consideration for critical mach is wing thickness ratio, and the Spit had a thinner wing than just about any other prop fighter.

From Nasa:http://history.nasa.gov/SP-367/fig90.jpg


It's clear that the plane expierencing MDD at higher speed will have far less drag at the point where it hasn't yet experienced MDD, and the other plane has.

- As far you "thinnest wing than on any major ww2
- fighter" - sorry, it`s hype. I have never seen
- anything that would support it, but even looking on
- drawings shows that it has absolutely ordinary, not
- at all thin wings.

Oryx has already given you the figures, but here's some more for you to look at:

http://www.aae.uiuc.edu/m-selig/ads/aircraft.html

Perhaps you could find the WW2 prop fighters with thinner wings?

- Anyway, irrevelant.

It's not irrelevant, it's THE crucial thin when it comes to high mach speeds.

From Nasa:

Thin airfoils: The wave drag rise associated with transonic flow is roughly proportional to the square of the thickness-chord ratio (t/c). If a thinner airfoil section is used, the flow speeds around the airfoil will be less than those for the thicker airfoil. Thus, one may fly at a higher free-stream Mach number before a sonic point appears and before one reaches the drag-divergence Mach number.

Indeed, the effect of swept wings is simply to reduce the effective thickness ratio.

Again from Nasa:

One may view the effect of sweep of a wing as effectively using a thinner airfoil section (t/c reduced). In figure 92(a) a straight wing is shown with the airflow approaching perpendicularly to the wing. Notice a typical airfoil section. If the wing is now swept to some angle of sweep , the same flow over the wing encounters new airfoil sections that are longer than previously. The maximum ratio of thickness to chord has been reduced.

XyZspineZyX
09-05-2003, 07:19 PM
While it was tested on several prototypes, it was not fitted on production aircraft.

I own copies of the factory documents (read scale plans) relative to the tanks used on serial production A8 and they are light alloy only tanks.
The two A8 manuals i own agree as well, and my copy of the A8 spare part manual also.

Moreover the various documents i own regarding A8 production says that while it was technically possible (replacing the tank) it was not normally done. And the cherry on the cake, no captured aircraft report or crashed aircraft investigation report i own mention fitting of a GM-1 tank.

GM-1 on the A8 could not be used below 8000m, and it was above the usual engagement alt which was between 6000m and 8000m, altitude where other kind of boost where more useful.

Butch

XyZspineZyX
09-05-2003, 07:21 PM
Vo101_Isegrim wrote:
- I am speaking in absolute terms, not relative ones.
- At the root the spit had about 35 cm thick wing,
- while 109s typically about 27cm... others are
- similiar as well, below 30cm.

You can't do this - when you are working with coefficients it is the ratios that are important, not the absolute thickness. The thickness ratios (as well as the shape of the airfoil of course) determine how much the local velocity change relative to the freestream velocity, and therefore determine the difference between the local Mach number and the freestream Mach number. Using absolute thickness instead of thickness ratio is quite simply wrong if what you are interested in is critical Mach number and drag divergence behavior. If you are interested, a good introductory book on compressible flow is "Modern Compressible Flow with Historical Perspective" by Anderson, although almost any good aerodynamics text will tell you the same thing that I wrote above.

- The simpliest example is
- the P-51s laminar flow wings vs. the Spits. I don`t
- think anybody would claim that the Spit`s wing
- design was actually better than the P-51s against
- compressibility effects... especially as it is
- PROVEN by tests that compressibility effects come
- early on Spits, but rather late on P-51s. See the
- NACA tests SC has reffered to. Sorry to say that,

The Mustang airfoil indeed had a high drag divergence Mach number for its thickness, but it is actually quite similar to the thinner Spitfire airfoil. The Spitfire airfoil had a high drag divergence Mach number due to low thickness, the P-51 airfoil had it due to the geometry and resulting shape of the pressure distribution.

And for your information, early compressibility effects and high drag divergence are not necessarily directly related, especially for something with a geometry as complex as that of an aircraft. It is quite possible for one part of the flow to shock locally while the rest stays subsonic for much longer.

- but again I see that it`s a hype ("thin wings
- explains it all") is supposed to prove another hype
- ("Spitfire, the highest Mach number reaching fighter
- of WW2"), again.

Quite right, thin wings do not explain it all. It is only one (though important) factor among many others.

XyZspineZyX
09-05-2003, 07:25 PM
MiloMorai wrote:
-
- Vo101_Isegrim wrote:

--
-- 100% . All were capable using it. It was a matter of
-- choice, wheter to load up C-3 fuel or NO2 in the
-- tank.
--
--
-
- The high performance 801s were in short supply. I
- can see your answer, so give production numbers.
-
-
- Why are you answering when the post was directed to
- Huckie?


What's to answer here? A5, A6, A8, G8, A9 were all fitted with R4 modification (GM-1 kit). Even if you have one single squadron for each model fitted those kits, you'll have over 100 aircrafts.

GM-1 kits were not fitted on late 109s, because there was no activity at those altitudes. Keep in mind that G2 fitted with GM-1 is faster than K4 at those altitudes. Since they renounced at this capability despite the improved performance and very low cost, it means that there was no real need for them. GM-1 kits for Bf-109 brought only 100kg more to loaded weight with GM-1 tank full. Much less than any high altitude supercharger. And it could be used for much more time than the pilot could spend fuel on full throttle. This is the reason why turbosupercharging was not adopted on Fw190A series, because of its bulkiness and no performance benefit over GM-1 kits.

GM-1 kits installed by FW brought 350PS more at high altitude. Have you seen that graph for A8 showing 620kmh with GM-1 use? Well that was not the max speed, because it was obtained at Steig und Kampfleistg not at Start und Notleistg.

at 30000ft
Steig und Kampfleistg: 830hp
Start und Notleistg: 950hp
Steig und Kampfleistg + GM-1: 1175hp
Start und Notleistg + GM-1: 1295hp

Which means that max speed at 30000ft is 620*(1295/1175)^(1/3) = 640km/h

This calculation gives good accuracy since you can estimate the same way the max speed at Start und Notleistg without GM-1: 620*(950/1175)^(1/3) = 578km/h which is confirmed by the chart.

640km/h was a very good performance at 30000ft. Very few planes were capable of it. I will try a better estimation for this, now that I have good data on A8.
And keep in mind that A9 were even faster.

That Fw190A did not have good performance at high altitude can be declared a myth. Only those not fitted with GM-1 were not performant at high altitude, but they were not supposed to do high altitude work.


<center> http://www.stormbirds.com/images/discussion-main.jpg </center>

XyZspineZyX
09-05-2003, 07:30 PM
- I am speaking in absolute terms, not relative ones. At
- the root the spit had about 35 cm thick wing, while
- 109s typically about 27cm... others are similiar as
- well, below 30cm.

It's only relative thickness that matters, not absolute. Wing thickness to chord ratio, given as a percentage. Again, from Nasa:

The wave drag rise associated with transonic flow is roughly proportional to the square of the thickness-chord ratio (t/c)


- Spitfire: 1-1 bulges for wheels,

Spit didn't have bulges for the wheels. They were contained within the wing.

- plus 2x2-2x2 bulges for Hispanos,

2, 1 each side. The larger dual bulge was only fitted to a few early examples with 2 20mm, or when 4 20mm cannon were carried. Or are you claiming now that all Spits carried 4 20mm?

- + 1-1 bulges for Brownings.

No bulges for the Brownings, either 303 or 50 cal.

- That`s 12

that's 2 actually,

XyZspineZyX
09-05-2003, 07:31 PM
Slickun wrote:
- I'm trying to talk about realities. What actually
- happened? Not a soul has questioned my assertion
- that the Spitfire did not use diving tactics
- regularly, either defensively or offensively.


The trials of the Spitfire XIV (and the XIV outdives
the IX) say:

"After the initial part of the dive, during which the FW 190 gains slightly, the Mk XIV has a slight advantage"

and

"During the initial part of the dive, the Me.109G pulls away slightly, but when a speed of 380 m.p.h. is reached, the Spitfire XIV begins to gain on the Me.109G. "

In other words, initially if you dive with a Spitfire,
you will be caught by a 109 or 190 (or it will pull away
if you are chasing it) but you will do better in a long
dive, but at the cost of losing squadron cohesion if you
are doing it individually. A short dive means that
your pursuer may well gain initially and be able to finish
you off, so it would be a poor choice of maneouver. But
the extended dive performance is good.

- The LW used them the entire war to escape Spitfires.

The 109 and 190 pull away initially. This puts them
at reduced risk of being shot down initially. To close
the kill the Spitfire has to continue the dive for
some time, splitting up the squadron, and making the
aiecraft that has dived vulnerable to being bounced.

Thus the 109 and 190 can escape enough to make it
tactically worthless for the Spitfire to follow -
it would have to break up the squadron to catch up.
It is more tactically useful for the Spitfire to let
the 190 or 109 to dive away, improving the odds
temporarily for the rest of the squadron, and concentrate
on winging closely. This might lead to an enhanced chance
of a LW aircraft remaining at co-altitude with the
squadron of being downed. The dived 109 or 190 may later
rejoin, but there is a tactical window of opportunity
before it does.

On the other hand, for a 109 or 190, a short dive may
lead to them catching up on the Spitfire, meaning they
may be able to (a) down it more easily, or (b) forcing
it into a long dive. (a) means the Spitfire is out of
the fight, and the 109/190 has lost little altitude,
and leaves its squadron disadvantaged for only a very
short time, but also means it can be short that that
Spitfire is not returning. Alternatively, (b) means
that the Spitfire will be a while rejoining its squadron.
The 109 and 190 are very good in a zoom climb, so the
time to rejoin is small, as they can quickly zoom climb
back to altitude. The Spitfire zoom climbs less well.

Hopefully that all makes sense...

- As I've said, we can all draw our own conclusions.
- It seems to be that the Spit accelerated very slowly
- in a dive, so slowly it wasn't a valid combat
- tactic, but just kept trucking until it could attain
- mach .89, a higher recorded number than any other
- prop plane in WW2.

It didn't need to go quite that far, according to the
AFDU.

XyZspineZyX
09-05-2003, 07:33 PM
butch2k wrote:
- Using C3 or GM-1 was not a matter of choice at
- all...
- No A-8 could take GM-1 since they were not equipped
- with the insulated tank but with the dual use
- (fuel/MW-50) light alloy tank.


Was A8 fitted with MW50? What was the boost then?



- GM-1 use was dropped altogether in most aircraft by
- mid 1944 when appeared clearly that the engagement
- altitude where below the minimum altitude of GM-1
- use. This led to the reconversion of a number of 109
- which previously used GM-1 to MW-50 use.


Butch your deduction that because Bf-109 didn't need GM-1 boost then GM-1 was abandoned on all aircrafts cannot be correct. In high altitude missions (as many as they were) Fw-190 should have used GM-1. I found the R4 modification mentioned with almost all later models after introduction on A5: A6, A8, A9 and G8. I don't believe that they didn't fitted it for high altitude missions, since they definitely needed it there. You could not risk the pilot life and plane when you could install such a simple kit to improve performance.



<center> http://www.stormbirds.com/images/discussion-main.jpg </center>

Message Edited on 09/05/0301:37PM by Huckebein_FW

XyZspineZyX
09-05-2003, 07:36 PM
Because Issy, all the span wise cracks cause turbulance, causes seperation of the airflow from the skin. dah!

Who said anything about trailing edges, Issy? Take some more English comprehension lessons.

No bulges for the mgs on the Spit./i/smilies/16x16_smiley-happy.gif

airfoil bending - what ever you say Issy. /i/smilies/16x16_smiley-sad.gif


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"Only a dead 'chamber pot' is a good 'chamber pot'!"

XyZspineZyX
09-05-2003, 07:47 PM
Production of the R4 kit by ago was dropped by the end of July 1944, in all they only produced just 11.
I checked my sources and found only one reference to an operational A-8/R4 which served in the 10./JG1.

Butch


Message Edited on 09/05/0308:51PM by butch2k

XyZspineZyX
09-05-2003, 07:53 PM
Going to make a retraction Huckie?

"Production of the R4 kit by ago was dropped by the end of July 1944, in all they only produced just 11.
I checked my sources and found only one reference to an operational A-8/R4 which served in the 10./JG1.

Butch"

Huckebein_FW wrote:

-
-
- What's to answer here? A5, A6, A8, G8, A9 were all
- fitted with R4 modification (GM-1 kit). Even if you
- have one single squadron for each model fitted those
- kits, you'll have over 100 aircrafts.
-
-

http://a1276.g.akamai.net/7/1276/734/625ed428e022ef/www.harley-davidson.com/PR/MOT/2004/Softail/images/DOM/img_Softail_FXST.jpg

http://www.redneckengineering.com/photogallery/photo23581/curves-done-03.jpg


"Only a dead 'chamber pot' is a good 'chamber pot'!"

XyZspineZyX
09-05-2003, 08:01 PM
hop2002 wrote:

--
-- Sorry Hop, but I afraid that your terminal speed
-- idea is a bit out of the world of reality. It`s
-- simply impossible for a given design aircraft to
-- just keep accelerating above a certain Mach number.
-
- I said it would keep accelerating until it broke up.
- WW2 fighters could not be put in to a full power
- vertical dive from high altitude and held there,
- they would simply break up. That's why pilot's notes
- give never-exceed speeds.

Pilot`s notes give never-exceed speeds because of the manufacturer`s guarantee. These numbers are sometimes very conservative, sometimes quite reckless.

Breaking up depends on G-load or the stress of the airframe has from vibration (which is again a type of G or acceleration).

Static forces, like drag you mentioned, are many times less dangerous, because they are constant with 1G or so acceleration.



- You have to have a very strong, low powered, high
- drag fighter to simply hit a "terminal speed" that
- won't allow you to go faster, and won't destroy the
- plane.
-

The 109F was very strong, low powered, and high drag design? Because it did in one - vertical dive at full power test - just what you described. It hit a mach number of .805, and even though it kept accelerating regards of TAS, it couldn`t hit any higher Mach number. Then the plane was pulled out rather violently into level flight.


-
- No, it will break up. Look at it this way, to reach
- a terminal speed, drag = thrust. In a full power
- vertical dive, you have the plane's normal thrust,
- plus gravity. For a Spit or 109, that means total
- drag reaches 7 - 10,000lbs.

eh-eh. If Drag=thrust -> plane hovers in the air. But we are speaking of diving planes here, which accelerate and loose altitude rapidly.


- These planes weren't
- built to withstand that sort of force, not combined
- with the turbulence that occurs at high mach
- numbers. For comparison, at around 400 mph in level
- flight, these planes expierenced what, around 1,000
- lbs of drag? Something in that range, and without
- the turbulence you get at very high speed as well.


See above why this is false.

-
- TAS doesn't matter much in aerodynamics, but mach is
- not the only thing that matters, IAS matters as
- well.

IAS and Mach goes hand to hand. Though the same Mach is reached at lower IAS at low temp.


- You can be safely within your mach limit, and
- still break up because IAS is too high. The Spit,
- Mustang etc could all do more than mach 0.8, but not
- at low level. 0.8 at low level is around 600 IAS,
- and I can assure you any Spit or Mustang trying to
- do 600 IAS at low level isn't going to last long.
-

In fact there are reports of planes surviving very high IAS numbers at low alts, and low Mach numbers are the key for this. High Mach usually means compressibilty and vibration, vibration means high levels of acceleration (G loads) to the structure, which again effectively _multiply_ the forces that react on the components, and one will fail.

So it`s the exact opposite, the higher you are, the more danger there`s in diving because of vibration. BTW, it corresponds with P-47 stories, the plane entering high MAch numbers and strong vibration at high alt, then it comes out of it as it enters lower alts with higher Mach corresponding IAS numbers.



-
- And I was simply trying to make it clear. Terminal
- speed means different things to different people, I
- was just clarifying, in light of your claim that the
- highest attainable speed could only be attained in a
- 90 deg dive.
-

90 degree dive is the best way, unless you have superheavy wingloading, with minimal lift. The more swallow your dive is, the more lift you produce. The more lift you have, the more drag you have... simple... the only thing that speaks vs. a near-90 degree dive is that if you accelerate slowly in a dive, you might "push" the Mach-for-IAS number in front of you as you loose altitude.


-- Basic physics, Hop. I already listed why the Spit
-- was in pretty much every regard bad for dives. It`s
-- high drag design.
-
- High drag at what speed?
-

High drag by default, Hop. It`s large, has pretty bad solutions (you cut out all of them /i/smilies/16x16_smiley-wink.gif ), which all work agaisnt it.


-
- Look at Neils chart. It shows the Spit at .0225 or
- so at lower speeds. By mach 0.85, it's up to .036 or
- so. That's what critical mach, or drag divergent
- mach speed, refers to. It's the much higher drag you
- experience when the airflow begins to compress and
- becomes turbulent.
-

In other words, you started with a high-drag design, and it naturally produces even more drag as Mach numbers rise...


- A plane can easily have higher drag at low speeds,
- and lower drag at high speeds, if it has a higher
- critical mach.

Again, you try to prove the thing with itself. "The Spit had high critical Mach, because it had lower drag at high speeds, which is possible because it had higher critical MAch."

The snake bites it`s own tail.



-
- The main consideration for critical
- mach is wing thickness ratio, and the Spit had a
- thinner wing than just about any other prop fighter.
-

It`s just one. Again, best example, P-51 "laminar-flow" wings. Thick wings, high mach. It seems airfoil has just as much, if not more, to do with it. It isn`t as simple as "thin wing = high mach". Turbulance over wing plays a major role, which the Spit had plentyful.



-
- It's not irrelevant, it's THE crucial thin when it
- comes to high mach speeds.
-
- From Nasa:
-
- Thin airfoils: The wave drag rise associated with
- transonic flow is roughly proportional to the square
- of the thickness-chord ratio (t/c). If a thinner
- airfoil section is used, the flow speeds around the
- airfoil will be less than those for the thicker
- airfoil. Thus, one may fly at a higher free-stream
- Mach number before a sonic point appears and before
- one reaches the drag-divergence Mach number.
-

It`s a highly generalised statement on a very complex issue.

Kinda like : Big tank = Good tank. So 'Maus' was the best, because it was the biggest?



-
- Indeed, the effect of swept wings is simply to
- reduce the effective thickness ratio.
-
- Again from Nasa:
-
- One may view the effect of sweep of a wing as
- effectively using a thinner airfoil section (t/c
- reduced). In figure 92(a) a straight wing is shown
- with the airflow approaching perpendicularly to the
- wing. Notice a typical airfoil section. If the wing
- is now swept to some angle of sweep , the same flow
- over the wing encounters new airfoil sections that
- are longer than previously. The maximum ratio of
- thickness to chord has been reduced.
-


It`s again more complicated than that. The main advantage of swept wings is their ability to reduce induce drag/turbulance, because they lead the airflow in a better way. Now again, Spit has no kind of sweep to speak about, while others - Mustang, 109 have, altough only slight ones.

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'Only a dead Indianer is a good Indianer!'

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XyZspineZyX
09-05-2003, 08:08 PM
Aaron, you have quoted tests from the best Spitfire, the 14, and it is still lukewarm.

You then continue on making the case that the dive just wasn't valid for the Spitfire in the ETO. We are all in agreement, beating a dead horse. It worked in the PTO, not in the ETO. We agree.


We are left with a chart, however, showing it to be the best diving machine in WW2. Except maybe the Tempest.

Make our own conclusions.

XyZspineZyX
09-05-2003, 08:10 PM
AaronGT wrote:
-
-
- The trials of the Spitfire XIV (and the XIV outdives
- the IX) say:
-
- "After the initial part of the dive, during which
- the FW 190 gains slightly, the Mk XIV has a slight
- advantage"
-
- and
-
- "During the initial part of the dive, the Me.109G
- pulls away slightly, but when a speed of 380 m.p.h.
- is reached, the Spitfire XIV begins to gain on the
- Me.109G. "
-


Yep, and what Mike Williams "forgot" to tell is that they tested a 109G with gunpods, and an old 190A-4, both with limited boosts. Neither being able to get over about 380mph in level flight (under given conditions).

The 380mph figure for the 109 is very telling, ie. it`s the max. speed it could reach on limited boost and with speed reduction from gunpods. So far this speed, 109G (w. gp and limited boost) dives better. After that, worser. Why? Because below 380mph, the engine could add to the dive. Above 380mph, it largely can`t. It`s the max. speed it could accelerate to. The Spit XIV, being faster than this given 109G, enjoys the fruits of engien power after 380mph, giving it the edge.

In other words, as long as the engine could accelerate the plane (=380mph), the Spit could not catch up. Now, given that the 109G airspeed under "fair" (max. boost, no gunpods) was much higher (400 to 440mph), the Spit was unlikely to ever catch up, before it hit it`s own maximum speed limit, after which the only thing it drove furhter was mother earth, = same power that drove it`s antagonist in dive. Since the MkIX were about as fast as 109Gs, this was exactly the case.



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'Only a dead Indianer is a good Indianer!'

Vezérünk a Bátorság, K*sérµnk a Szerencse!
(Courage leads, Luck escorts us! - Historical motto of the 101st Puma Fighter Regiment)

Flight tests and other aviation performance data: http://www.pbase.com/isegrim

XyZspineZyX
09-05-2003, 08:15 PM
hop2002 wrote:

-
-- Spitfire: 1-1 bulges for wheels,
-
- Spit didn't have bulges for the wheels. They were
- contained within the wing.

Nope, they had bulges for the wheels. Look for any drawing, Spit I to XIV, perhaps...


-
-- plus 2x2-2x2 bulges for Hispanos,
-
- 2, 1 each side. The larger dual bulge was only
- fitted to a few early examples with 2 20mm, or when
- 4 20mm cannon were carried. Or are you claiming now
- that all Spits carried 4 20mm?

Whaterver. 2 bulges for u/c, plus 4 for the Hispanos. Don`t forget the cannon barrels neither, they lay in front of the leading edge...


-
-- + 1-1 bulges for Brownings.
-
- No bulges for the Brownings, either 303 or 50 cal.

Maybe look below the wings, too...


-
-- That`s 12
-
- that's 2 actually,

Nope, 2 for the l/g, 4 for the Hispanos, plus 2 for the two innner? brownings in the wings bottom. 8 in total, plus the change (access hatch etc, but those are on every a/c, so let`s be generous...).

Of course, if you add another pair of Hispanos (which were common according to some http://ubbxforums.ubi.com/infopop/emoticons/icon_wink.gif ), you get 12 nice bulges. Plus cannon barrels.


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'Only a dead Indianer is a good Indianer!'

Vezérünk a Bátorság, K*sérµnk a Szerencse!
(Courage leads, Luck escorts us! - Historical motto of the 101st Puma Fighter Regiment)

Flight tests and other aviation performance data: http://www.pbase.com/isegrim

Message Edited on 09/05/0309:33PM by Vo101_Isegrim

XyZspineZyX
09-05-2003, 09:36 PM
Vo101_Isegrim wrote:
--
-- High drag at what speed?
--
-
- High drag by default, Hop. It`s large, has pretty
- bad solutions

So you think the '109 had good drag solutions? Look at the carbuncles festooning the nose of an Emil. The hollow spinner. The braced tailplane. Look again at Willi's second attempt: the big, blunt (some might say 'fat') spinner of the Friedrich and its later brethren; the primitive, angular glasshouse and the large 'beulen' over the Gustav's ammunition feed- belts. Even Willi didn't like the beulen so he tried again- the result? An asymmetric fuselage- yes, that's right, one that bulged significantly more on the port side than on the starboard side due to the unfortunate incidence of the side- mounted compressor intake.
Tell us black is white, Isegrim, but do not try to convince us that the '109 was somehow aerodynamically more efficient than a Spitfire. Any Spitfire.

XyZspineZyX
09-05-2003, 09:49 PM
Issy being selective again for he forgot the 2 bulges for the wing/fuselage connection on the 109. He also failed to mention that the wheel bulges got bigger. Or the struts for the elevator mass balances.


http://a1276.g.akamai.net/7/1276/734/625ed428e022ef/www.harley-davidson.com/PR/MOT/2004/Softail/images/DOM/img_Softail_FXST.jpg

http://www.redneckengineering.com/photogallery/photo23581/curves-done-03.jpg


"Only a dead 'chamber pot' is a good 'chamber pot'!"

XyZspineZyX
09-05-2003, 10:05 PM
Stewbie wrote:

- So you think the '109 had good drag solutions? Look
- at the carbuncles festooning the nose of an Emil.
- The hollow spinner. The braced tailplane.

Sure, the Emil was unimpressive. Still, faster than the vast majority of British airplanes at that time. On less power. /i/smilies/16x16_smiley-very-happy.gif

- Look again
- at Willi's second attempt: the big, blunt (some
- might say 'fat') spinner of the Friedrich and its
- later brethren;

LOL, you are mad m8. Your spinner remarks are laughable. Funny to note how similair are today`s high Mach jet`s big, blunt noses. /i/smilies/16x16_smiley-very-happy.gif

Sea Level speeds:
Bf 109F-2: 507 km/h at 1.35ata
Bf 109F-4: 537 km/h at 1.42ata
Spitfire MkV : 460 km/h

Of course, while Messerscmitt improved, Spitfire didn`t changed at all...


- the primitive, angular glasshouse
- and the large 'beulen' over the Gustav's ammunition
- feed- belts.

Still, still faster than Spitfires on less power. /i/smilies/16x16_smiley-very-happy.gif

Level speeds at SL:

Bf 109G-6, with DB 605A-1 at 1.3ata : 510 km/h
Spitfire MkV, with Merlin 45 :460 km/h
Spitfire MkV, with DB 605A-1 at 1.3ata : 483 km/h

It tells it all.


- Even Willi didn't like the beulen so he
- tried again- the result? An asymmetric fuselage-
- yes, that's right, one that bulged significantly
- more on the port side than on the starboard side due
- to the unfortunate incidence of the side- mounted
- compressor intake.

Yep, and this time about 50 km/h faster than Spitfires on less power. /i/smilies/16x16_smiley-very-happy.gif

So, while Messerscmitt improved it`s airframe again and again, added retractable tailwheel, wheel doors, a perfect fusalge, what did they do at Supermarine?

The exact opposite. They added bulges for cannons, machiguns, they added an engien 300 kg heavier, consuming 50% more, which requested for more fuel, more weight again, and, the give the coup d`grace, they added some horrendous bulges to the top of the engine cowling for the Griffon, to make it as ugly and inefficent as possible.


Your comments are good for a joke, they show MASSIVE ignorance.



-
- Tell us black is white, Isegrim, but do not try to
- convince us that the '109 was somehow
- aerodynamically more efficient than a Spitfire. Any
- Spitfire.


I don`t try to tell that bacause it`s plain obvious to anyone but mindless zealot zombies that the Supermarine Bumpfire was the worst WW2 fighter aircraft when it come to aerodynamic effiency, whereas the Me 109 was the best, along with the P-51 and Yak-3 IMHO.




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'Only a dead Indianer is a good Indianer!'

Vezérünk a Bátorság, K*sérµnk a Szerencse!
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Message Edited on 09/05/0311:31PM by Vo101_Isegrim

XyZspineZyX
09-05-2003, 10:09 PM
A through search always yields results! /i/smilies/16x16_smiley-happy.gif

Interesting to note, that the Mustang they tested was a war-weary MkI. with Allison engine, vs. an unarmed Spitfire photo recon plane with special high altitude engine...

Well why am I not surprised ? Neil Sterling is no better than Mike Williams when it comes to hiding the details... I felt that it by no accident that he cut off the lower part of the details section...



This is just a partial list of structural failures and dive-related accidents involving RAF Spitfires. The following is from SPITFIRE: THE HISTORY, Eric Morgan & Edward Shacklady. Most of the data on the chart is quoted from the aircraft construction lists, although some information is found in the text sections of the book and this is noted by page number.

--------------------------------------------------
Mar 39...Mk I....K9838...Structural failure in dive.
Jan 41...Mk I....N3191...Both wings broke off in dive.
Jul 41...Mk I....X4354...Port wing broke off in dive.
Aug 41...Mk I....X4381...Starboard wing broke off in dive.
Mar 41...Mk I....X4421...Both wings broke off in dive pullout.
Jul 41...Mk I....X4662...Stbd wing broke off in dive pullout.
Jun 41...Mk I....X4680...Wings/tail broke off in dive pullout.
Nov 42...Mk I....X4621...Failed to recover from dive.
Apr 43...Mk II...P7352...Broke up in dive.
Sep 41...Mk II...P7522...Both wings broke off in dive.
Jun 43...Mk V....BL531...Both wings broke off in dive.
Feb 42...Mk V....AA876...Disintegrated in dive.
Jul 43...Mk V....BL389...Pilot thrown from aircraft in dive.
Jan 43...Mk IX...BS251...Structural failure in dive.
May 43...Mk IX...BS385...Structural failure in dive.
Aug 43...Mk IX...BS441...Disintegrated in dive.
Oct 46...Mk IX...PL387...Disintegrated in dive.
Jan 48...Mk XVI..SL724...Crashed after recovery from dive.
Sep 48...Mk XVI..TD119...Crashed after recovery from dive.
--------------------------------------
Aug 42...Mk I....N3284...Broke up in flight.
Aug 41...Mk I....N3286...Broke up in flight.
Sep 40...Mk I....P9546...Structural failure in flight.
May 42...Mk I....P9309...Lost wing in flight.
Apr 43...Mk I....X4234...Lost wing in spin.
Sep 42...Mk I....P9322...Broke up in flight.
Aug 43...Mk I....R6706...Aileron failure which led to crash.
Jan 43...Mk I....X4854...Starboard wing broke off in flight.
Nov 40...Mk II...P7593...Stbd wing and tail broke off in flight.
Dec 41...Mk II...P8183...Port wing broke off in flight.
Jun 42...Mk II...P8644...Starboard wing broke off in flight.
May 41...Mk II...N8245...Structural failure in flight.
Feb 44...Mk II...P7911...Flap failure which led to crash.
Sep 42...Mk V....AD555...Flap failure which led to crash.
Mar 44...Mk V....BL303...Flap failure which led to crash.
Dec 41...Mk V....BL407...Structural failure suspected.
Jun 42...Mk V....AB172...Structural failure in flight.
Mar 43...Mk V....AA970...Structural failure in flight.
Jun 43...Mk V....BL290...Port wing broke off in flight.
May 43...Mk V....BR627...Port wing failed in spin.
Oct 41...Mk IV...AA801...Structural failure in flight.
Feb 43...Mk IX...BS404...Structural failure in spin.
Feb 45...Mk IX...MH349...Wing failed during aerobatics.(pg.318)
Sep 46...Mk IX...MJ843...Port wing, tailplane broke off in loop.
---------------------------------------
Apr 43...Mk V....EP335...Wings, fuselage, tail, damaged in dive.(pg.63)
Jul 42...Mk VI...AB200...Wings buckled in dive at 450mph IAS.
Apr 44...Mk IX...MA308...Wings severely buckled around cannons.(pg.63)
Feb 44...Mk XI...EN409...Many wing rivets failed in dive.(pg.389)
Apr 44...Mk XI...EN409...Prop/gear broke off at 427mph IAS.(pg.389,399)
Nov 44...Mk IX...MH692...Tail section damaged in dive.(pg.318)

In addition, the construction lists identified a few Spitfires that broke up in bad weather, but I did not include those.

WING and TAILPLANE FAILURES
In July 1941, Spitfire Mk I - X4268 was used to investigate wing failures by taking measurements of internal pressure on the wings. In June 1942, Spitfire Mk II - P7251 was used to investigate tailplane failures, by taking measurements of tailplane deflection in high speed dives. Eventually it was judged that the port and starboard tailplane tips were at slightly different angles in a dive and this caused an excessive degree of twist in the airframe. That could be overcome to some extent by applying full left rudder, although using full right rudder made the problem much worse. The summary says that the terminal velocity of the Spitfire was about 560mph TAS.

In July 1942, there was a meeting at the MAP to discuss the chronic aileron problems with the Spitfire. After six years of flight testing this aircraft, surprisingly little progress had been made at improving the aileron response at high speeds.That includes the results of replacing fabric ailerons with metal ones, and associated attempts to add inertia weights to the elevator system. Pilots involved in the aileron testing noted that as speed increased, the rate of aileron upfloat increased suddenly and disproportionately. Squadron Leader Raynhan of the Accidents Branch asserted that the most significant fact emerging from recent Spitfire accidents was that no change in the type of failure had been brought about by the introduction of the inertia device or by readjusting the center of gravity, which he believed pointed to aileron instability. Also, there had been evidence of ailerons flying right up at a very early stage of the accident in certain instances, and failures of the aileron circuit which could not be explained by the wings breaking off the aircraft in flight.

When the tail unit failed on a Spitfire, it often sheared off at fuselage frame No. 19. In 1942, an official at RAE Farnborough noted that out of 36 Spitfire accidents, the tail unit had broken off in flight during 24 of these mishaps.By 1944, the Spitfire was often used in the fighter-bomber role and it was reported that the engine mounting U frames had frequently buckled in dive pullouts. About 35 Spitfires from Biggin Hill Wing were found to have this fault.

After the Spitfire Mk V had been in service for some time, alarm had been raised over several accidents where the aircraft simply dived straight into the ground for no apparent reason. The Accidents Branch investigated this matter and later determined that firing the 20mm cannons could damage the oxygen regulating apparatus, so that thereafter the rate of supply could not be varied and could lead to the pilot losing consciousness. "



And on Martindale`s "dive tests":



"He did not reach Mach .91 on this occasion (or any other occasion according to SPITFIRE: THE HISTORY). It says the pilot was Squadron Leader A.F. Martindale, and the max speed reached in this dive was only about Mach .80.

Martindale began the dive from 40,000ft, reaching 600mph ASA at 27,000ft (about 427mph ASI) when the airscrew and reduction gear sheared off. The aircraft was Spitfire PR Mk XI -- EN409 and the date was 27th April 1944. On the bright side, the Spitfire soon glided better than usual with its propeller missing. In February, Martindale had dived the same aircraft from 40,000ft and popped a large number of wing rivets on the way down, causing a serious loss of stability and he needed to wrestle the control stick with both hands. Morgan & Shacklady's study has an overwhelming mass of data on the aircraft, and there is no mention of any Spitfire reaching Mach .91 in a dive.

There was a flight at Farnborough in January 1944, in which a Spitfire PR Mk XI dived from 40,000ft and allegedly reached a top speed of .89 Mach at 29,000ft. A Mustang Mk I tested about the same time had an Allison engine with considerably less power and a low altitude blower. This means the aircraft was old and probably war weary. This aircraft began its dive from only 28,000ft and reached a top speed of Mach .80 at 17,000ft. Dive angle normally used was 45 degrees, using a gentle pullout of 2-3 G.

In March 1944, Spitfire Mk IX - BS310 tested in diving trials at Boscombe Down and did no better than Mach .83. Not surprisingly, this Spitfire developed a longitudinal pitching movement, the elevators became very heavy and there was considerable turbulence around the cockpit. Based on the Spitfire's tendency to break apart in flight, it is unlikely that any reached Mach .89, let alone Mach .91. Most likely a hiccup in the guages which was nothing unusual. Where it involved the increasing air disturbance at .90 Mach, piling on more instruments did not guarantee accuracy with 1944 standards.



Well, so much for the claim "typical" Spitfire dive speeds... those things typically did not reach it and broke up well before it seems.

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XyZspineZyX
09-05-2003, 10:30 PM
S! All

The have been some excellent points made here requarding the P47. I have flown about every WW2 prop sim and it seemed to me that EAW had modeled the Jug the best so far. It was the standard US Iron energy fighter that needed altitude to compete against axis planes. EAW was designed as a medium to high alt flight sim--escorting bombers was a primary mission. Even though EAW was designed for these altitudes, it's low altitude F/M was good also. Conversley FB was designed as a low alt sim and it's high alt F/M needs much improvement.

The P47's well known for it's diving ability and zoom climb. Robert S. Johnson talks about in his book being able to outzoom climb 190's, and hammerhead back down on top of them. EAW modeled this well. The P47D accelerated much faster in a dive in EAW than FB and if you werent careful compressibilty would occur rapidly.

I can dive the FB P47D (bubble canopy) from 7500m to a speed of over a 1000kph to around 1500m without sustaining damage. It sure takes a long time to get going and it bleeds energy very fast when zoom climbing. It can out dive the K4 & D9 but they end just catching the Jug on the deck. Over 900kph, both the K4 and D9 sustained damage when I flew them. Maybe you guys will experience something different.

The 47 was a very stable gun platform and should not have the spread that it currently has. The 190 seems immune to .50cals and the damage modeling of the 2 planes seems reversed. While it is true that the 190 is more diffcult to shoot down than the 109, the 190 should not be nearly impossible. Bud Anderson shot 3 190's down in one mission in his P51 with only 6 .50cals.

Also the "Vector Roll" was utilized at medium to higher speeds to be able to turn with a 109. This did not mean the pilot would stay in a sustained turn with a 109, it just offered another firing solution. But I hope that this illustrate to you an idea that the Jug could manuever well for it's size--of course it was not as nimble as a 109.

These are just my observations in comparing the P47 in different flight sims.

file:///C:/My%20Documents/My%20Pictures/Aviation%20Art%20Central-P40.jpg

file:///C:/My%20Documents/My%20Pictures/Aviation%20Art%20Central-P40.jpg

XyZspineZyX
09-05-2003, 10:37 PM
Pilots Notes, Spitfire IX,XI and XVI.
Ignor the hand written part.


http://hometown.aol.co.uk/JStirlingBomber/Spit+man1.jpg

XyZspineZyX
09-05-2003, 10:42 PM
Neil, why did you cut off the part which tells that the "Mustang" was a P-51A, and that it was dived down at much lower altitudes?

Not so good for the Glory, eh ?

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'Only a dead Indianer is a good Indianer!'

Vezérünk a Bátorság, K*sérµnk a Szerencse!
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Flight tests and other aviation performance data: http://www.pbase.com/isegrim

XyZspineZyX
09-05-2003, 10:53 PM
BigKahuna_GS wrote:
The 190 seems
- immune to .50cals and the damage modeling of the 2
- planes seems reversed. While it is true that the 190
- is more diffcult to shoot down than the 109, the 190
- should not be nearly impossible. Bud Anderson shot 3
- 190's down in one mission in his P51 with only 6
- .50cals.
-

The manouverability and topspeed of the D-9 is reduced significantly by just a few hits on the wings.

http://members.chello.se/unni/GK-2.JPG


'When it comes to aircombat, I'd rather be lucky than good any day!'

XyZspineZyX
09-05-2003, 10:53 PM
http://hometown.aol.co.uk/JStirlingBomber/Spitdrag+4a.jpg

XyZspineZyX
09-05-2003, 11:00 PM
Vo101_Isegrim wrote:
-
- Neil, why did you cut off the part which tells that
- the "Mustang" was a P-51A, and that it was dived
- down at much lower altitudes?


So from that graph posted by neilstirling with correlation between Cd and Mach number half of those Spits crashed? I'm sure that high Mach dives in Spits were quite an asset for the british pilot in combat/i/smilies/16x16_smiley-very-happy.gif


<center> http://www.stormbirds.com/images/discussion-main.jpg </center>

XyZspineZyX
09-05-2003, 11:10 PM
Huckebein_FW wrote:
-
- So from that graph posted by neilstirling with
- correlation between Cd and Mach number half of those
- Spits crashed?

Frankly, I tend to believe that in fact there was a single plane, Spit PR XI, factory no. EN 409, which was dived in January, in which test the British claimed .89 Mach for it, then it was dived down again in February and it started to fell apart, rivets popped out etc.

Finnaly, in April 1944 they managed to sheer the whole propellor together with the reduction gear.

Then, in September 2003, they tell that it was "typical dive performance"... meaning a single dive that could not be repeated anymore, was most likely an error in the instruments, and which dives, when tried to be repeated, resulted in broken planes only.


- I'm sure that high Mach dives in
- Spits were quite an asset for the british pilot in
- combat. /i/smilies/16x16_smiley-very-happy.gif

Yep, if the Brits ever had the problem of having too many pilots at hand, high Mach dives in Spitfires was a reliable cure for it...



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Flight tests and other aviation performance data: http://www.pbase.com/isegrim

XyZspineZyX
09-05-2003, 11:51 PM
- Pilot`s notes give never-exceed speeds because of
- the manufacturer`s guarantee. These numbers are
- sometimes very conservative, sometimes quite
- reckless.

Why bother if the plane would simply hit a limit and stay there?

- Static forces, like drag you mentioned, are many
- times less dangerous, because they are constant with
- 1G or so acceleration.

There is nothing constant about the drag you experience at airspeeds like this. That's the whole point. Ever hear pilots talk of "buffeting" in high speed dives?

- The 109F was very strong, low powered, and high drag
- design? Because it did in one - vertical dive at
- full power test - just what you described. It hit a
- mach number of .805, and even though it kept
- accelerating regards of TAS, it couldn`t hit any
- higher Mach number. Then the plane was pulled out
- rather violently into level flight.

Got the details? The bit where he says the plane maintained a steady speed, and wouldn't go faster, rather than him simply deciding enough was enough?

Regardless, those tests were carried out from a much lower initial height, iirc.

- eh-eh. If Drag=thrust -> plane hovers in the air.

You still believe in Aristotle's laws of motion, rather than Newton's, I see.

Aristotle
Force = Mass x Velocity.

Netwon
Force = Mass x Acceleration

Aristotle believed if you take away the force, the velocity declines. Netwon proved if you take away the forces, velocity remains where it was when acceleration finished.

In other words, if there is no net force on an object, it continues travelling in the same direction, at the same speed.

A diving aircraft has 2 forces (at least) acting on it. Thrust, and drag. When thrust is greater than drag, the plane is accelerating. When thrust is less than drag, it is decellerating. When thrust and drag are equal, it is moving at a steady state, ie a constant speed.

If a plane has 8000lbs of thrust, it will accelerate until it has 8000lbs of drag (or breaks up). When it has 8000lbs of drag as well as 8000lbs of thrust, it has reached it's maximum speed.

-- These planes weren't
-- built to withstand that sort of force, not combined
-- with the turbulence that occurs at high mach
-- numbers. For comparison, at around 400 mph in level
-- flight, these planes expierenced what, around 1,000
-- lbs of drag? Something in that range, and without
-- the turbulence you get at very high speed as well.
-
-
- See above why this is false.

See above why it's true. A Spit in a 90 deg dive has around 8000lbs of thrust, and will continue to accelerate until it has 8000lbs of drag.

-- TAS doesn't matter much in aerodynamics, but mach is
-- not the only thing that matters, IAS matters as
-- well.
-
- IAS and Mach goes hand to hand. Though the same Mach
- is reached at lower IAS at low temp.

No they don't.

0.8 mach is around 608 mph at sea level (standard atmosphere). That's also 608 IAS, or course.

At 30,000ft, 0.8 mach is 542 mph TAS, about 329 mph IAS. (standard atmosphere)

That's why ww2 fighters had two limits, an IAS limit, and a mach limit. You had to obey whichever was lower.

The Spit, for example, had a 470mph IAS limit. Try going 470 IAS at 30,000ft, and you are well over the speed of sound.

That's why it also had a mach limit of 0.85 or so (iirc, can't be bothered to look it up again)

The Mustang had a higher IAS limit, 505 iirc, but a somewhat lower mach limit.

- So it`s the exact opposite, the higher you are, the
- more danger there`s in diving because of vibration.

Both are dangerous. At high alt, you will exceed mach limit, and experience severe transonic drag, which causes loss of control, and risks structural failure.

At low level, you will exceed the IAS limit, which causes loss of control (not to such an extent, usually), and can cause structural failure.

Note, modern fast jets at high speed at low level are rated on how many 0.5 G bumps they experience per minute, with too high a level meaning the crew will not function effectively. High speed at low level, even if well within critical mach, will cause turbulence and risk structural failure.

- BTW, it corresponds with P-47 stories, the plane
- entering high MAch numbers and strong vibration at
- high alt, then it comes out of it as it enters lower
- alts with higher Mach corresponding IAS numbers.

The P-47 had a fairly large problem at high mach numbers, and much less of a problem at high IAS numbers.

- 90 degree dive is the best way, unless you have
- superheavy wingloading, with minimal lift. The more
- swallow your dive is, the more lift you produce. The
- more lift you have, the more drag you have...

Induced drag is a very small factor in level high speed flight. At these sorts of dive speeds, it's almost neglible.

- High drag by default, Hop. It`s large, has pretty
- bad solutions

By far the largest drag at mach 0.8 [plus is transonic drag. It's negligible at mach 0.6, but quickly grows to become the largest factor by 0.8.

The lowest drag fighter at mach 0.8 is simple, it's the one with the lowest transonic drag. Look at Neils graph, or the Nasa one I posted. There is a sudden, large increase in drag above "critical mach", and it is by far the largest drag force on the plane at those speeds.

- In other words, you started with a high-drag design,
- and it naturally produces even more drag as Mach
- numbers rise...

No, transonic drag is different to normal drag. It's not a simple scaling up of the forces at lower speed.

- Again, you try to prove the thing with itself. "The
- Spit had high critical Mach, because it had lower
- drag at high speeds, which is possible because it
- had higher critical MAch."
-
- The snake bites it`s own tail.

No, I try to explain HOW it could have lower drag. For an explanation of WHY, read what Nasa says again:

The wave drag rise associated with transonic flow is roughly proportional to the square of the thickness-chord ratio (t/c)

- It`s just one. Again, best example, P-51
- "laminar-flow" wings. Thick wings, high mach. It
- seems airfoil has just as much, if not more, to do
- with it.

No, airfoil has something to do with it, and a "better" airfoil can make some difference.

As Nasa point out, thin wings have disadvantages, (more expensive, less lift, less room). So, if airfoil shape is more important than thickness, then modern fast jets would be designed with fairly thick wings, but of better design, right?

Plane root tip
Mig 27 6.5% 5.5%
F 15 6% 3%
F-16 4%

Modern "supercritical" designs increase that somewhat, but they are still thin by WW2 standards.

XyZspineZyX
09-06-2003, 12:07 AM
- Nope, they had bulges for the wheels. Look for any
- drawing, Spit I to XIV, perhaps...
-

I could show you pictures, if you like. Spits with the C or E wing did not have wheel well blisters, apart from very late war, when they began to be fitted to the Spit XVI, along with a change in wwheel geometry, to counteract high wear on concrete runways.

In other words, most Mk Vs onwards didn't have wheel blisters, a few late war IXs and XVIs did.

- Maybe look below the wings, too...

Can't see any bulges there, either.

- Nope, 2 for the l/g,

Only for the V, and some late war clipped wing XVIs.

plus 2 for
- the two innner? brownings in the wings bottom.

Nope, still none for the Brownings. Try p412 of Spitfire the History. Cross section of 50 cal installation, no bulges above or below the wing.

- Of course, if you add another pair of Hispanos
- (which were common according to some http://ubbxforums.ubi.com/infopop/emoticons/icon_wink.gif ), you get
- 12 nice bulges. Plus cannon barrels.

Find a quote where I say they were common, please. And I will check to make sure I actually said it.

So, on Most Vs, all VIIs, almost all IXs, XIIs, XIVs etc:

2 bulges for Hispanos

That's it.

XyZspineZyX
09-06-2003, 12:19 AM
- This is just a partial list of structural failures
- and dive-related accidents involving RAF Spitfires.
- The following is from SPITFIRE: THE HISTORY, Eric
- Morgan & Edward Shacklady. Most of the data on the
- chart is quoted from the aircraft construction
- lists, although some information is found in the
- text sections of the book and this is noted by page
- number.

Spitfire the History lists over 22,000 Spitfires and their fates. What Isegrim has posted is a list of 50 or so accidents out of the 22,000 or more built. By his own admission, one third of 109s were lost inaccidents, so over 10,000 109s were lost inaccidents.

After all, didn't Lucas Schmidt say that the 109 was prone to having one of it's undercarriage legs sucked out at high speed, with catastrophic results.

All planes were subject to structural failure, for example the VIIIth AF were losing a couple of Mustangs a week to wing failures, unrelated to combat.


"The Mustang had been dogged by instances of structural failure, particularly since the marriage to the Merlin. Flight restrictions on dives and other manoeuvres were imposed, but in the course of combat, these sometimes had to be ignored. The puzzling thing about Mustang airframe failure was that it could not be pinpointed to any one area and was sometimes encountered in brand-new aircraft that had not undergone any known flight strain. Engines tore loose from fuselages, wings were shed, and empennages crumpled and while most of these incidents happened during a sharp manoevre it was a fact that other Mustangs would engage in the same manoevre time and again without any sign of failure. Some components were strengthened - notably the fin and undercarriage door locks (which had a nasty habit of breaking open) - but a few cases of airframe failure were regularly reported to the end of hostilities and beyond." - Roger Freeman, "Mustang at War".


"'I witnessed this [Mustang wing] loss on two occasions. One wing was lost directly over the airfield at Madna, Italy in the fall of 1944. The airplane and pilot went straight into the ground not far from the control tower. One other loss occurred there during an afternoon 'rat race.' Coincidentally we were discussing this wing loss with Johnny Typer, the civilian representative from NAA at the time. He was adamant that no-one could pull the wings off a P-51. No sooner had he made that remark than I heard behind me the dull thumps of two wings separating. He asked 'What's that?' and I answered that it had happened again. He asked how I knew, to which I replied, 'Once you've heard that sound, you'll never forget it." We watched as the litter and tumbling wings fell slowly to the ground, long after the fuselage and pilot had crashed - an unforgettable sight and feeling." - Lt. William G. Coloney, 52nd FG, quoted in the Spick book mentioned above.


- And on Martindale`s "dive tests":
-
-
-
- "He did not reach Mach .91 on this occasion (or any
- other occasion according to SPITFIRE: THE HISTORY).
- It says the pilot was Squadron Leader A.F.
- Martindale, and the max speed reached in this dive
- was only about Mach .80.

Who said he did?


- In March 1944, Spitfire Mk IX - BS310 tested in
- diving trials at Boscombe Down and did no better
- than Mach .83. Not surprisingly, this Spitfire
- developed a longitudinal pitching movement, the
- elevators became very heavy and there was
- considerable turbulence around the cockpit.

BS310 was testing different prop designs, none of which were adopted afaik.

XyZspineZyX
09-06-2003, 12:22 AM
Dives as tactics ---

Would you dive after a plane that could start the dive faster than you and probably zoom climb better than you? If so then you're a bit dumb. Why? Robert S. Johnson showed why. The leader dives and the turkey follows, then the leader zooms and the turkey can't follow which leaves the leader in a superior position.

I can't say for sure about a 109 (but I'd say probably) but a 190 should be able to turn the tables on a chasing Spit and a P-47 should at least be safer using such tactics than most of the rest of its limited repertoire. In fact, I'd say that the better plane in vertical tactics along a more level average flight might just be the better one in diving and zooming as well.

The P47 should be good to the limits of its smash, or speed, and before that's used up it's time to extend in it. In diving, the P47 just adds to its smash. Ditto for the 190 except that it climbs and accelerates better but I bet the long dive and zoom aren't quite as good. All in all, I'd rather have the FW190 of the same period as it's a better overall fighter something like the Fokker DVII in WWI. Still, the P47 had strengths and they could be used well.


Some of you guys::::: are whizzing in the pool with you p!ssing contest. I can smell the ammonia, it's so bad! How aboutagree to disagree?


Neal

XyZspineZyX
09-06-2003, 12:22 AM
- So from that graph posted by neilstirling with
- correlation between Cd and Mach number half of those
- Spits crashed?

Whatever gave you that idea?

Isegrim posted a list of approx 50 failures from a list of more than 22,000 Spits built. Brokenclaw, the guy who's post Isegrim has simply copied off the OnWar forum, spent weeks checking through 900 pages of Spitfire The History to compile it.

XyZspineZyX
09-06-2003, 01:55 AM
Hey Huck.

I read the A-8 GM-1 situation. In other words:

http://members.cox.net/rowlandparks/speed.jpg


/i/smilies/16x16_smiley-very-happy.gif


Don't let it bother you. Being mad never changed anything.



Regards,

SkyChimp

http://members.cox.net/rowlandparks/corsairs.jpg

XyZspineZyX
09-06-2003, 02:43 AM
No apoligy from Huckie yet for calling you a forger SC?

---------

>>SC, hop<<

it is a good thing the Allies kept good records./i/smilies/16x16_smiley-wink.gif Unfortuately, but convenient for Issy, the simular records for German a/c were almost completely destroyed or lost.



http://a1276.g.akamai.net/7/1276/734/625ed428e022ef/www.harley-davidson.com/PR/MOT/2004/Softail/images/DOM/img_Softail_FXST.jpg

http://www.redneckengineering.com/photogallery/photo23581/curves-done-03.jpg


"Only a dead 'chamber pot' is a good 'chamber pot'!"

XyZspineZyX
09-06-2003, 10:16 AM
Slickun wrote:
- We are left with a chart, however, showing it to be
- the best diving machine in WW2. Except maybe the
- Tempest.
-
- Make our own conclusions.

Slickun, it depends on what you mean by 'best'.

The Spitfire definitely _doesn't_ have the best
diving characteristics for use tactically.

It could
(I'd put can - but I don't think anyone with a
vintage Spitfire's going to try and get mach 0.89
out of it!) reach a high maximum mach number in
a dive, though, although at relatively high altitude
where it is able to do high mach with out exceeding
its IAS limit.

Which makes it 'best'?

XyZspineZyX
09-06-2003, 03:22 PM
hop2002 wrote:
-
- Spitfire the History lists over 22,000 Spitfires and
- their fates. What Isegrim has posted is a list of 50
- or so accidents out of the 22,000 or more built.

A PARTIAL list, I must add. In any case, not even StH denies that the Spitfire had troubles in dives, and that the claimed ,89 Mach could never be repeated by any other plane. In fact, its very likely that the same - unarmed - plane that supposedly dived to ,89 broke up in a dive a few months later...

So much about the claim for "typical" dive performance... it was a single case, most likely thez never even reached it, just the instruments went crazy.


- By
- his own admission, one third of 109s were lost
- inaccidents, so over 10,000 109s were lost
- inaccidents.

Sorry, I never said any such thing. You twist my words. I said that out of the 109s lost (which is WAY less then 33 000) according to unit logbooks, about 1/3 were lost to non-combat reasons. That includes writing them off because of aging etc.



-
- After all, didn't Lucas Schmidt say that the 109 was
- prone to having one of it's undercarriage legs
- sucked out at high speed, with catastrophic results.
-

Twisting it again of course...

-
- All planes were subject to structural failure, for
- example the VIIIth AF were losing a couple of
- Mustangs a week to wing failures, unrelated to
- combat.
-

Mustangs were prone to wing failure, just like Spitfires. What does that prove? Nothing.

-
-- And on Martindale`s "dive tests":
--
--
--
-- "He did not reach Mach .91 on this occasion (or any
-- other occasion according to SPITFIRE: THE HISTORY).
-- It says the pilot was Squadron Leader A.F.
-- Martindale, and the max speed reached in this dive
-- was only about Mach .80.
-
- Who said he did?
-
-
-- In March 1944, Spitfire Mk IX - BS310 tested in
-- diving trials at Boscombe Down and did no better
-- than Mach .83. Not surprisingly, this Spitfire
-- developed a longitudinal pitching movement, the
-- elevators became very heavy and there was
-- considerable turbulence around the cockpit.
-
- BS310 was testing different prop designs, none of
- which were adopted afaik.

OK, concentrate on the subject: BS 310 was tested in diving trials, could not do better than Mach .83. Neither could any other Spit in dives, which makes the claim for "typical" diving speeds suspicious again.

So what we have on hand, that the Brits claim that the Spitfire could typically dive to Mach .89. In reality, only a single, unarmed version of the Spit is claimed to have done that, which is still dubious, as the same plane broke up at much lower speeds somewhat later on...

http://vo101isegrim.piranho.com/FB-desktopweb.jpg
'Only a dead Indianer is a good Indianer!'

Vezérünk a Bátorság, K*sérµnk a Szerencse!
(Courage leads, Luck escorts us! - Historical motto of the 101st Puma Fighter Regiment)

Flight tests and other aviation performance data: http://www.pbase.com/isegrim