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Superjew1
07-19-2009, 01:48 AM
I dont get it, everytime I go into a dive from about 10,000ft and reduce the prop pitch down to %10, and try to pull out from 2,000 feet up, the controls dont respond and I fly straight into the trees.

IS there something wrong with the game, the p38, or is it the pilots fault that I keep crashing into the ground from a steep dive in my p38?

I notice that I seem to have to hit above 500mph for it to happen, but have only done it 2x.

JtD
07-19-2009, 01:59 AM
The P-38 has extremely heavy controls at high speeds. You need to trim up a lot if you want to pull out from this low.

Why do you reduce prop pitch to 10%?

Freiwillige
07-19-2009, 02:12 AM
It was a real life issue with the P-38. Once it had reached a certain speed compressiblity became a major life or death issue. The shockwave would disrupt the airflow flowing over the horizontal stabilzer and it couldnt get enough airflow over it to pull you out. Later p-38's had dive recovery flaps (Dive break key in sim) to help you recover.

The Luftwaffe exploited this weakness knowing that a P-38 wouldnt follow in a steep dive.

mortoma
07-19-2009, 06:44 AM
Pop your combat flaps and that also will help you recover in the early J model P-38. In the later models you have an air brake, which is a Godsend.

AndyJWest
07-19-2009, 07:21 AM
This topic has been discussed in forums before, I think.

IL-2 Compare gives the max dive speed (VNE in pilot-speak) as 820 km/h for th P38-J and 880 km/h for the L models. A quick check on the QMB shows that nothing falls off at that speed, at least at low level (I was starting at 5000m and diving fairly shallowly on full power). The problem is that (a) there is a marked pitch down effect as speed increases, which needs to be trimmed out, and (b) the control effectiveness reduces markedly. I don't know how IL-2 Compare derives its figures, but they seem reasonable to me, in that dive recovery will be so sluggish. Diving at full throttle at VNE is probably safer than throttled back, simply because to stay within the limit, the dive will have to be shallower. Don't know whether it is good for the engines though.

I'd forgotten about the dive brakes myself, and haven't tried combat flaps: in my tests (J & L Late only) I recovered ok without. You could maybe also try sideslipping to slow down a bit though I haven't tried it.

I think I'll do a few more tests, simply because I've been flying P38s quite a bit lately, and ought to know for sure what I can get away with

Daiichidoku
07-19-2009, 07:53 AM
Originally posted by Superjew1:
a dive from about 10,000ft,

the controls dont respond

IS there something wrong with the game, the p38, or is it the pilots fault



it is the game

despite the fact that it would happen to every WWII type, Oleg saw fit to add compressability to the P 38 only

the compressability he put on it, at that, is complete hogwash, IRL the P 38 could not reach its critical mach speed in dives started below 20,000ft

RegRag1977
07-19-2009, 08:11 AM
Originally posted by Daiichidoku:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Superjew1:
a dive from about 10,000ft,

the controls dont respond

IS there something wrong with the game, the p38, or is it the pilots fault



it is the game

despite the fact that it would happen to every WWII type, Oleg saw fit to add compressability to the P 38 only

the compressability he put on it, at that, is complete hogwash, IRL the P 38 could not reach its critical mach speed in dives started below 20,000ft </div></BLOCKQUOTE>

And the 109, don't forget the 109... http://forums.ubi.com/images/smilies/10.gif

BillSwagger
07-19-2009, 08:26 AM
In a previous post there was discussion about compressibility and how its seldom modeled properly in games.
One flaw that i see in many sims is that they cut out or limit elevator control as soon as the plane reaches its critical mach, but the reality is that the plane would need to go a bit faster for the shock wave to be big enough to engulf the air going over the elevators. Most planes would shutter and buffet, and have trouble with controlling ailerons before experiencing loss of elevator control, but i'm not sure if there was an exception with the P-38.
It is also a gradual effect on control surfaces not an on and off phenomenon.


Another flaw i see is the altitude and the degree the compressibility effect is modeled.
It is related to altitude and speed, and generally you need to be going faster at lower altitudes to have a similar effect, however at lower altitudes there is also more air pressure against the control surfaces. This is a double edge sword, meaning that compressibility effects can be more severe at lower altitudes, but also easier to recover from, provided the plane isn't damaged.

AndyJWest
07-19-2009, 08:27 AM
I'm not sure it is compressability as such that is modelled, more that at those speeds, the P38 has negative pitch stability: as it speeds up, the nose goes down. This can catch you out in other fast aircraft in the sim, though the P38 is possibly the most notable example.

I did a few more tests, and starting from 10000m in a shallowish full power dive, you will get marked buffeting as you get to VNE, and structural failure will occur if you go much faster. I got lucky once, though - the elevator fell off, and the aircraft pitched up into steep climb, slowing enough for a bailout. I suspect that which failure occurs is probably random, or at least not easily predicted, but whatever happens, it is unlikely to be pleasant.

I am assuming that the speeds given by IL2 Compare are indicated airspeed, rather than true airspeed, though in any case, the buffeting is always a clue that you are going too fast for safety. It takes time to learn the quirks of an aircraft, and I'd rather have a plane that does this, than one that spins if you sneeze (no names here, I don't want to offend the Pxx pilots) http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif

Daiichidoku
07-19-2009, 08:54 AM
Originally posted by RegRag1977:
And the 109, don't forget the 109... http://forums.ubi.com/images/smilies/10.gif

compressability not modeled on 109s

only P 38 and B1 rocket

general_kalle
07-19-2009, 10:46 AM
Originally posted by Daiichidoku:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by RegRag1977:
And the 109, don't forget the 109... http://forums.ubi.com/images/smilies/10.gif

compressability not modeled on 109s

only P 38 and B1 rocket </div></BLOCKQUOTE>
if not, then whats causing the Me109 to be difficult to pull out from +500 kmh dives???

danjama
07-19-2009, 02:32 PM
+1 on 109 being crap at high speed thanks to heavy elevs

AllorNothing117
07-19-2009, 02:49 PM
It's been said many times but it all boils down to this...

It happened in real life, but only above certain altitudes. It is exagerated in IL-2, however IRL trim would not have solved the problem like it does in IL-2. See this video for an example of a real pilot suffering from this and then recovering at lower altitude where the air was thicker. Compression was the death of many pilots who were unaware of the risks of high altitude, high speed dives in the P-38. It make Booming a Zooming very impractical.

Here's the Vid http://www.youtube.com/watch?v=ITRLk9b9AcY

^_^

AndyJWest
07-19-2009, 03:39 PM
A few further thoughts on the P38 dive characteristics, and another quick test:

Firstly, it seems that if you dive vertically at zero throttle, with no airbrakes deployed, the acceleration is so great that you will need to pull out long before you reach the VNE, as with limited elevator response it takes a heck of a long time to pull horizontal, and you will still be speeding up as you do. I broke 3 P38s doing this in tests, and one time even had the computer reset http://forums.ubi.com/images/smilies/compsmash.gif, though this was probably coincidence http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif

Secondly, perhaps the flight model IS different for the P38 than other aircraft, but whether this is a flaw in the way it is modelled, or a lack of accuracy in the other aircraft, I don't know. Certainly some aircraft (e.g. Fw 190D) seem to shed control surfaces before they lose sufficient elevator response to pull out, given reasonable altitude, but if the surface you lose is the elevator, you may be in deep trouble http://forums.ubi.com/groupee_common/emoticons/icon_frown.gif

All this suggests that to get the best out of the P38 you need to be familiar with (a) what the VNE of the plane is,(b) how it handles as you approach VNE, and (c) how easy it is to accidentally exceed it in different conditions. Many of the sim aircraft have VNE warnings on the control panel but you also have the benefit of immortality, unlike real pilots, and can break a few in the process - I think that if I'm going to be flying online in one, I'll warm up offline first with a few high-speed dives and a spin or two for familiarisation. Takeoff is not too difficult in the P38, though having to hold down elevator on to maintain nosewheel steering is a bit odd, and I rarely get the chance to land in online games anyway, so there's no need to practice these...

AndyJWest
07-19-2009, 04:19 PM
Originally posted by AllorNothing117:
It's been said many times but it all boils down to this...

It happened in real life, but only above certain altitudes. It is exagerated in IL-2, however IRL trim would not have solved the problem like it does in IL-2. See this video for an example of a real pilot suffering from this and then recovering at lower altitude where the air was thicker. Compression was the death of many pilots who were unaware of the risks of high altitude, high speed dives in the P-38. It make Booming a Zooming very impractical.

Here's the Vid http://www.youtube.com/watch?v=ITRLk9b9AcY

^_^

Just watched the vids. Good stuff! The P38 in the sim seems to handle pretty much like the real thing, from the look of it, given the limitations of what is after all a pretty old piece of software. I wouldn't like to have to use the emergency gear deployment system though, as shown in part two of the 2nd vid: http://www.youtube.com/watch?v=pDmIB7u18_0


Pump the handle for three minutes, and if that doesn't work, move the selector valves, and pump again for another three! http://forums.ubi.com/images/smilies/53.gif

M_Gunz
07-19-2009, 04:44 PM
As happened IRL the P-38 only went so fast below 10,000 ft that they could pull up, but that's not a signed blank check.
How fast can they dive below 10,000 ft in game?

IRL the P-38 has a low critical Mach compared to many mid and late war fighters.

deepo_HP
07-20-2009, 09:42 AM
Originally posted by Daiichidoku:
the compressability he put on it, at that, is complete hogwash, IRL the P 38 could not reach its critical mach speed in dives started below 20,000ft so the ingame p-38 is modeled too fast, i presume? as it reaches critical mach below 3000?

as andyjwest posted earlier, in a dive controls get very heavy, but not too heavy to get out of a dive with 850kmh. i can recover in less than 800m needed, even when ailerons already left me.

what is critical mach-speed at an altitude of 1000m? i mean in tas?


hi m_gunz,

i start losing parts from 850kmh on in the p-38j, usually rudder and ailerons first. but i have reached 920kmh (1400m) and recovered - though not manoeuverable anmore

AllorNothing117
07-20-2009, 03:30 PM
Just to Clarify the vid I posted, is about P-38 compression. The One in my sig is sperate, but still worth watching!

Bremspropeller
07-20-2009, 04:25 PM
if not, then whats causing the Me109 to be difficult to pull out from +500 kmh dives???

The 109 has a "heavy" elevator.
The game doesn't simulate the pilot's ability to take the second hand and apply mora force to the stick.

The P-38 and BI-1 in turn have a "tuck under" effect modelled in-game.


In short words:
The 109 won't just pull up, while the P-38 will even lower it's nose on top of that.

Both effects are completely unrelated.

M_Gunz
07-20-2009, 04:25 PM
Originally posted by deepo_HP:
hi m_gunz,

i start losing parts from 850kmh on in the p-38j, usually rudder and ailerons first. but i have reached 920kmh (1400m) and recovered - though not manoeuverable anmore

That's plenty fast, a track of pullout with all parts stay on at 800+ might go a long way to shut some posts up, hey?

AndyJWest
07-20-2009, 04:35 PM
Track of 800+ Kmh IAS in P38 shouldn't be a problem, from my tests: What format of track do you want ? I'm new to this forum & don't know what is best. How do I send it to you? (This is probably a dumb question)

I'll also do one of VNE exceeding breakup, so you can se what happens & when.

[EDIT--------------------------------------------------------------------------------]

I've done both tracks. Do you want .trk or .ntrk?

I'm now looking to see how to upload them...

deepo_HP
07-20-2009, 05:21 PM
Originally posted by M_Gunz:
That's plenty fast, a track of pullout with all parts stay on at 800+ might go a long way to shut some posts up, hey? my first attempt: diving up to 950kmh, losing one rudder and one aileron, recovering and manoeuvering a bit.
p38j_dive950.ntrk (http://www.dadatainment.info/wb/p38j_dive910.ntrk)

my fourth attempt: diving up to 910kmh, starting pullout at 1900m, recovering at 1000m, doing a bit manoeuvering and crashing into the blue seas.
p38j_dive910.ntrk (http://www.dadatainment.info/wb/p38j_dive910.ntrk)

Trefle
07-20-2009, 05:28 PM
Originally posted by AndyJWest:
[EDIT--------------------------------------------------------------------------------]

I've done both tracks. Do you want .trk or .ntrk?

I'm now looking to see how to upload them...

.NTRK (native track) is the format used when you want others to view your track without alterations of the original (.trk will not work well on other people's comp , the track will run differently )

Dkoor showed me this website for hosting tracks , it works well http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif :
http://www.datafilehost.com/

AndyJWest
07-20-2009, 06:33 PM
As requested: two .ntrk files of my dive tests.

The first shows a P38L Late diving to 850 kmh IAS, recovering, and then diving again to 800 kmh. There is no strutural failure, and the aircraft remains in control. I didn't intend the second part of the dive to get quite as low as it did...

http://www.datafilehost.com/download-76285ea2.html

The second shows structural failure (preceded by heavy buffeting: see in-cockpit view), at 900 kmh+

http://www.datafilehost.com/download-a9f38775.html

These tests only take a couple of minutes to do in QMB: try it for yourself http://forums.ubi.com/images/smilies/25.gif

M_Gunz
07-20-2009, 07:03 PM
I'm not always so steady to keep a plane intact approaching 900kph, except for P-47 and like of course.

These tracks are for the perpetual suffering members who always say the P-38 locks up at high speed and should not.
Well okay, it's more for the suffering members (some new) who perpetually >read< that the P-38 locks up, etc.

Tracks are good for supporting claims and they are even better for disproving claims.

BillSwagger
07-20-2009, 07:18 PM
Originally posted by general_kalle:
if not, then whats causing the Me109 to be difficult to pull out from +500 kmh dives???

deep stall....

the elevators are in the wake of the wing in a turn. At high speeds the wake is large enough that it disturbs the air flow going over the elevator, soon as you pull back, pitching the tail into the wake of the wing.

this image exaggerates what im talking about.
http://upload.wikimedia.org/wikipedia/commons/thumb/8/88/Deep_Stall.png/300px-Deep_Stall.png

http://farm3.static.flickr.com/2399/2304009187_5d301ccc6b.jpg?v=0


In other planes, like the P-38, compressibility is a factor. The nose begins to tuck and requires elevator deflection to counter it.
The problem is that compressibility can also limit elevator control if the air going over the elevator is disturbed by the shock wave.
In effect a plane would go into a steeper dive that gets more difficult to pull out of.
Dive flaps were put on planes in the event that this occurs.
even so, this is not modeled in Il2, but lack of elevator response is.

AndyJWest
07-20-2009, 07:28 PM
Originally posted by M_Gunz:
I'm not always so steady to keep a plane intact approaching 900kph, except for P-47 and like of course.


Neither am I, but the P38 is easier in some ways, as the lack of torque effects means that you really only have to to deal with 4 factors:

(A) Your IAS. KEEP WITHIN THE VNE http://forums.ubi.com/images/smilies/53.gif
(B) Elevator control - keep the changes in pitch gentle, and beware divergence: i.e. nosing down.
(C) Elevator trim, to simplify the above (but be gentle)
(D) Height above ground: you can happily get all the above right, and still make a big crater if you don't pull out in time http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif

In a combat situation, you will also have other factors to consider, and don't expect anything but mediocre roll response at these speeds.

As I suggested earlier, a power dive, necessarily shallower, is safer than a steep zero-throttle Stuka impersonation, though again in combat, tactical considerations come into play.

I think that tomorrow I will do some testing on control effectiveness at these speeds, i.e. can you rip the wings off by hauling right back...

Daiichidoku
07-20-2009, 08:50 PM
Originally posted by AndyJWest:
lack of torque effects


FB game engine makes no allowances for contra-rotating props/no torque, as its based on original IL2 engine, which was intended for only one flyable, the IL2, hence no consideration was given to modeling a lack of torque

M_Gunz
07-20-2009, 09:08 PM
Originally posted by BillSwagger:
Dive flaps were put on planes in the event that this occurs.

This is the first time I *ever* heard that 109's had dive flaps!
We've been shown account of a 109 diving over 900kph -indicated- and recovering through careful use of trim,
why didn't he pop those dive flaps?

The in-game P-38's that had dive flaps IRL also have them in IL2. Are you sure that 109's had them?

M_Gunz
07-20-2009, 09:12 PM
Originally posted by Daiichidoku:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by AndyJWest:
lack of torque effects


FB game engine makes no allowances for contra-rotating props/no torque, as its based on original IL2 engine, which was intended for only one flyable, the IL2, hence no consideration was given to modeling a lack of torque </div></BLOCKQUOTE>

What, did someone send out for troll?

Which way do the IL2 P-38's torque, with both engines running equal? I don't even have to counter propwash on takeoff!

BillSwagger
07-20-2009, 09:47 PM
Originally posted by M_Gunz:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by BillSwagger:
Dive flaps were put on planes in the event that this occurs.

This is the first time I *ever* heard that 109's had dive flaps!
We've been shown account of a 109 diving over 900kph -indicated- and recovering through careful use of trim,
why didn't he pop those dive flaps?

</div></BLOCKQUOTE>

no, i didn't mean to imply that 109s had dive flaps.

I'm saying on planes that experience compressibility tuck.
I'm not sure 109s are even capable of reaching speeds safely that they would encounter compressibility. I'm not sure though. I do know that they didn't have dive flaps.
People often complain of their mushy elevator response at high speed, so i'm offering the deep stall explanation.
The problem is more exaggerated in planes with a t-tail configuration but it would still be an issue for planes, like the 109, at high speeds because the stabilizer sits just above the height of the cockpit. The wake of the wing increases as the angle of attack does, shadowing the tail from getting decent airflow.

It doesn't completely stall the tail, but this could be reason for mushy response at higher speeds. ( in a 109)

M_Gunz
07-20-2009, 11:36 PM
Me-163 doesn't have em and it did hit compression in level flight!
What was done company to company let alone country to country is a wide span of solutions or sometimes not-solutions.

Kettenhunde
07-21-2009, 12:35 AM
deep stall....


Hi Bill,

Deep stall is not the issue. There are some really good discussion on the Bf-109's stability and control at high speed on these forums. You can search and find them. Many of them have the original Mtt investigations into high speed flight in the Bf-109 design.

In summary, a high stick force per G by design is the issue with your games Bf-109 elevators.

IIRC, your pilot is restricted to ~50lbs of pull force which is not enough at high speed. The aircraft was limited by stability and control issues at Vne which is typical. A structural change was made to the design which raised the q-limits.

All the best,

Crumpp

Bremspropeller
07-21-2009, 03:19 AM
deep stall....

the elevators are in the wake of the wing in a turn. At high speeds the wake is large enough that it disturbs the air flow going over the elevator, soon as you pull back, pitching the tail into the wake of the wing.

Deep stall is only an issue on T-tails or cross-tails, not on conventional- or V-tails.

AndyJWest
07-21-2009, 07:12 AM
I don't really know enough about aerodynamics to comment much about the causes of the IRL P38 'flaw', but here's further input on the sim plane, which was what the original question seemed to be about.

Firstly, a vertical dive at zero throttle is a very different beast from the shallow power dives in may earlier tracks, and needs to be handled very differently:

(A) The rate of acceleration is VERY rapid - no time to play about with trim etc, so if you want to approach VNE vertically, you will have to time the pullout very accurately.
(B) You need to deploy divebrakes to pull out.
(C) Deploying the divebrakes causes a marked pitch-up effect, so you will probably black out from the G.

For an example of a P38 impersonating a Stuka -

http://www.datafilehost.com/download-3a2f1296.html

I wouldn't want try it with a bombload, too much to think about if you are trying to hit something, though the extra drag might reduce acceleration a bit? http://forums.ubi.com/images/smilies/blink.gif

Note that in the track I use the divebrakes as a pull-out system, deploying them as I reach 800 km/h IAS, and reaching about 830 as I level out. The brakes are really used more of a pitch-up aid than a means of increasing drag in this example.

If anybody actually does vertical or near-vertical P38 dive bombing, I'd be very interested to hear what technique they use, and whether it is effective or not: anyone out there got a track?

P.S. Don't forget that the P38 J has no divebrakes, and a lower VNE. http://forums.ubi.com/images/smilies/blush.gif

Daiichidoku
07-21-2009, 01:05 PM
Originally posted by deepo_HP:
so the ingame p-38 is modeled too fast, i presume? as it reaches critical mach below 3000?



testing has shown the P38L "late" only barely reaches RL 38 L performance

in game 38J climb with 25% fuel and max power matches RL 38J climb with 100% fuel and military power

this indicates that top speeds for in game 38s are likely undervalue (btw, the oft-quoted "414mph" figure for 38J is MILITARY power, not max (war emergency) power)


in any event, AFAIK the critical mach value in game is a fixed value (again AFAIK 420 mph true), but far too low a value as the plane gets lower in alt, where IRL the critical mach value steadily increases

http://upload.wikimedia.org/wikipedia/en/thumb/f/fe/Compressibility010.png/800px-Compressibility010.png


bear in mind, at .68 mach the 38 develops buffet, a warning of what is to come, yet is still quite controllable

at [edit] .74 mach is when mach tuck starts, and is more or less the "point of no return" for the 38

Daiichidoku
07-21-2009, 01:19 PM
Originally posted by M_Gunz:
What, did someone send out for troll?

Which way do the IL2 P-38's torque, with both engines running equal? I don't even have to counter propwash on takeoff!

troll eh? you have any evidence that what i said is false, or that lack of torque is indeed modeled in FB? http://forums.ubi.com/groupee_common/emoticons/icon_rolleyes.gif

mr. Gunz, please take a 38 and stall it to get your answer as to which way it torques


http://jamesreese.org/hangarflying/Issue2.htm

We have discovered that the power stall occurs at about 70 M.P.H. with about a 50-foot loss of altitude. The counter rotating propellers eliminate torque and there is no tendency for either wing to dip or fall away

You will find "she" is just as steady in a power off stall with gear and flaps retracted or extended.One of the finest characteristics of the '38 is the accelerated stall. Such stalls, accompanied by normal buffeting, occur on any ship when the angle of attack is increased to the point that the airflow over the wing becomes turbulent.
As you know, this can happen in sharp turns, pull-outs or other severe maneuvers. The '38 is designed to take the buffeting of the stall and has no tendency to fall off on either wing at any altitude. If combat necessitates, you can hold it in the accelerated stall as long as you can take the buffeting -- the ship will take it much longer. To get out of an accelerated stall immediately, ease up on the stick, permitting the airflow to reestablish normal lift.



let us know if what happens even remotely resembles the above, M.Gunz

deepo_HP
07-21-2009, 01:46 PM
hi daiichidoku,

rgr that.

i managed to get to 520mph (ias), resp. 890km/h (tas), in a steeper dive (100%fuel, crimea-map). i started pull-out at ~3500ft, ~500mph with zero throttle by uptrimming and slight elevator. still buffeting, i went on with controlled flight at ~1600ft, no parts lost:p38j_520ias.ntrk (http://www.dadatainment.info/wb/p38j_520ias.ntrk)

wouldn't that confirm the compression graph enough?

BillSwagger
07-21-2009, 02:31 PM
Originally posted by Bremspropeller:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">deep stall....

the elevators are in the wake of the wing in a turn. At high speeds the wake is large enough that it disturbs the air flow going over the elevator, soon as you pull back, pitching the tail into the wake of the wing.

Deep stall is only an issue on T-tails or cross-tails, not on conventional- or V-tails. </div></BLOCKQUOTE>

Actually stalling the tail in a deep stall may be limited to t-tails, however the phenomenon was known to occur in many planes, although not as extreme as completely stalling the tail. It wasn't officially called a "deep stall" until a plane crash resulted. The crash was attributed to the planes t-tail design.

I dont see how this may not have been an issue with the 109, but others have claimed it was due to the high stick force required to control the elevators at high speed.

robtek1957
07-21-2009, 02:46 PM
@Daiichidoku

in the matter of simulated torque:
please take a single engine plane with a narrow wheelbase, i.e. BF109, step on the brakes and rev the engine up. You will see that one wingtip rises while the other one descends!
Now repeat that with a p-38, voila the wingtips stay even.
The force, that you have seen simulated, is the torque!
There is no need to refer to a only marginally predictable Flight-situation which doesn´t prove anything.

Daiichidoku
07-21-2009, 03:19 PM
http://findarticles.com/p/arti...307/ai_n9283659/pg_2 (http://findarticles.com/p/articles/mi_qa3897/is_200307/ai_n9283659/pg_2)

Flight testing the P-38 disclosed that whenever the airflow over the wing exceeded Mach 1.0, compressibility effects were encountered. This result was soon predictable when this slippery fighter accelerated in excess of 0.65 Mach in dive angles greater than 45 degrees at altitudes above 15,000 feet.

the 45 degree figure is from pilots manual, which will always be conservative, and even at that, the figure is meant for sustained dives
there is accounts of Milo Burcham doing sustained 60 degree dives with no problem


http://findarticles.com/p/arti...307/ai_n9283648/pg_4 (http://findarticles.com/p/articles/mi_qa3897/is_200307/ai_n9283648/pg_4)

William H. Allen flew with the 55th Fighter Group and recalls P-38 dive-- bombing missions. "Dive-bombing depended on the fuse setting; sometimes, they were three-second delays, which meant a higher release altitude, and they went up to 19-second delays, where we would drop from 10 feet in a level attitude and let the bomb skip up to the target. We would normally start our run at 8,000 to 10,000 feet and roll over, point at the target and drop when we got nervous. Dive speeds were no problem with the P-38 below 12,000 to 15,000 feet."

Daiichidoku
07-21-2009, 03:26 PM
Originally posted by robtek1957:
@Daiichidoku

in the matter of simulated torque:
please take a single engine plane with a narrow wheelbase, i.e. BF109, step on the brakes and rev the engine up. You will see that one wingtip rises while the other one descends!
Now repeat that with a p-38, voila the wingtips stay even.
The force, that you have seen simulated, is the torque!
There is no need to refer to a only marginally predictable Flight-situation which doesn´t prove anything.

the 38 does not have a narrow wheelbase

M_Gunz
07-21-2009, 05:27 PM
In excess of .65 Mach does it matter what angle the P-38 is diving or is that the angle and alt where it could?
At .68 you get the buffeting characteristic of shock waves on the control surfaces and .74 is Mach Tuck time.

P-47 critical Mach is .76 as opposed to .65 or .68 and P-51 critical is higher than P-47.

Does IL2 use a fixed TAS to set the planes' critical Mach? 420 IAS at 10,000 ft (from the chart) is not 420 TAS.

When I look for torque I don't stall into a spin since once you push that far any little bit of uncoordinated rudder
can tip it over and at some point you won't be able to hold balance if you just hang back on the stick. But with a
bit less stick back I can get most planes to fall straight in stall with power low enough even with torque and I can
get them to climb with power high enough, P-40's and 109's both at 140kph IAS though it is tricky... clean stall on
a G-6 power off is about 155kph.
So I look for torque in steep climbs at low speed and which way I have to hold rudder to keep the plane straight.
I'll fire IL2 up and have a look as soon as my current download queue is finished, or sooner wth I can pause that
and resume later just to make sure. I'm looking for gyro, wash and p-factor in that one test.

deepo_HP
07-21-2009, 05:39 PM
Originally posted by Daiichidoku:
"Dive speeds were no problem with the P-38 below 12,000 to 15,000 feet." so what were the dive speeds then?
the game allows recoverable dives with speeds up to structural damage. how much more do you think, it should be?

Bremspropeller
07-21-2009, 05:58 PM
In excess of .65 Mach does it matter what angle the P-38 is diving or is that the angle and alt where it could?
At .68 you get the buffeting characteristic of shock waves on the control surfaces and .74 is Mach Tuck time.

No, it doesn't metter at all.

But I guess that angle was required to keep the aircraft accelerating and thus reaching tuck-under speeds.

M_Gunz
07-21-2009, 06:56 PM
So I take a P-38J up and steep climb at different power settings from 60% to 100%, pitch trimmed fully back and hand off
the stick except when I see what rudder will do (still using the twisty stick for rudder) and I find that above 170kph
it flies itself just fine but 170 and below there is a very slight tendency on my PC with my gear to twist rightwards.

Is this torque, input hardware not being ==>exact<== or roundoff?

It will happily fall off to the left if I tip to the left but *very* slightly left and it just stays there until it
slows down even more. By 160kph it really wants to drop a wing, either wing, and by 150kph it's rudder dance with
some quick moves to stay level even while climbing at 100% power -- I'm well into the stall but still have lift and
anyone who thinks you lose ALL lift in the stall just go check that again, the lift curve doesn't stop at the top.

Two torque sources separated side to side do cancel in some ways and do not completely in others, just BTW.
Compared to the single engine planes I've done the lowest speed climbs with, the P-38J is near dead tame on need for
rudder to keep level.

After I got tired of that I did some dives with pullout below 3000m and was able to pull out at over 800kph -- this
is in a P-38J. Somewhere past 880kph I lost parts and still pulled out though I had cut power when I hit 860.

At 10,000 ft on a Standard Day the speed of sound is 734.6 mph. At 5,000 ft it is 748.0 mph
At 3000m an IAS of 800 kph returns a TAS of 957 kph. 880 kph IAS gets me 1052.7 kph TAS at 3000m, 966.9 at 1500m.
There are 1.609 km (rounded close) per mile.
1052.7 kph gets me 654 mph, 966.9 kph gets me 600.9 mph, 880 kph gets me 546.9 mph, 800 kph gets me 497 mph.

Lets go with the lower numbers. I started to pull out at over 800 kph on the speedbar and below 3000m alt, gives
me 497 mph IAS. At 1500m the TAS is 897 kph for 557.5 mph TAS at 4,500 to 5,000 ft alt. I am being generous here.
That's .745 Mach and I did pull out from higher speed at a bit higher alt. I won't bother with track since tracks
have already been posted and I won't bother with UDPSpeed data since I feel there is no need to play fine points
about this.

I can certainly go faster, lose more parts than an aileron and probably augur in if I just push it. Pilot accounts
of pulling out at below 10,000 ft were from pilots I presume were actually trying to pull out and not commit suicide.
The simple FACT that many P-38s did not pull out of steep high speed dives in places where ground level was below
10,000 ft should attest to P-38s actually not pulling out once below 10,000 ft.

If anything, the IL2 P-38 can either dive "too fast" or more likely no sane IRL P-38 pilot would fly like a gamer
trying to push an agenda.

NOTE: edited for spelling and adding the word ALL before lift

Daiichidoku
07-21-2009, 09:48 PM
Originally posted by M_Gunz:
It will happily fall off to the left if I tip to the left but *very* slightly left and it just stays there until it
slows down even more. By 160kph it really wants to drop a wing, either wing, and by 150kph it's rudder dance with
some quick moves to stay level even while climbing at 100% power -- I'm well into the stall but still have lift and
anyone who thinks you lose ALL lift in the stall just go check that again, the lift curve doesn't stop at the top.

Two torque sources separated side to side do cancel in some ways and do not completely in others, just BTW.

so the troll was not actually a troll, and there IS torque on the 38?

more food for thought...

http://findarticles.com/p/arti...307/ai_n9283659/pg_2 (http://findarticles.com/p/articles/mi_qa3897/is_200307/ai_n9283659/pg_2)

Where the aircraft really came into its own was in performing stalls. The counter-rotating propellers kept the aircraft pointing straight ahead, so there was no torque effect to require rudder input as the speed decreased. Stalls demonstrated a good, early buffet warning, and no wing dropping occurred at the stall, even with small, pilot-applied aileron and rudder inputs to try to irritate its lateral and/or directional attitudes near the stall. It was even more impressive to me when I performed single-engine stalls with one engine either windmilling or feathered. With one of the P-38's dual fins and rudders always in the slipstream of a live engine, a stall could be performed with little or no wing drop. It was a pilot's dream under the trying conditions of a single-engine approach and landing.




Originally posted by M_Gunz:
Compared to the single engine planes I've done the lowest speed climbs with, the P-38J is near dead tame on need for
rudder to keep level.


it IS tame, i agree with you there...although the torque modeling for single engine types in game is completely undermodeled and token at that

Aviar
07-21-2009, 10:23 PM
Where the aircraft really came into its own was in performing stalls.

How very true. (However, this applies to real life performance, not in-game.)

The P-38 had a very low stall speed. Furthermore, when stall speed was reached, there was no wing drop. The nose would simply angle down.

I've actually seen P-38 stall test videos and it's incredible to witness. The in-game P-38 does not even come close to modeling this aspect of the FM.

Aviar

JtD
07-21-2009, 10:27 PM
The P-38 speed limit was very close to 450 mph TAS at all altitudes. They were far more easily reached at higher altitudes, where the plane could get into problems making high speed level runs or diving at even at a shallow angle.

deepo_HP
07-22-2009, 12:31 AM
short and rightly said, jtd.

deepo_HP
07-22-2009, 12:39 AM
Originally posted by Aviar:
I've actually seen P-38 stall test videos and it's incredible to witness. The in-game P-38 does not even come close to modeling this aspect of the FM. i've actually seen videos of what the ingame p-38 can do in aerobatics, and if it is as incredible as the p-38 stall test videos or not - it is in much aspect exceptionel and maybe in some manoeuvres only possible for the p-38's design. including counterrot-props:
papillon (http://www.vimeo.com/3431020)
(read the end-credits as well)

maybe the flip at stall-speed (at 1:20 - a description of which is given by fw_solo in the moviemaker-section of this forum) just needs a lot of practice, as the stall-pilots in your videos probably also had. just reading about the capabilities won't make them show ingame.

M_Gunz
07-22-2009, 01:42 AM
Originally posted by Daiichidoku:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by M_Gunz:
It will happily fall off to the left if I tip to the left but *very* slightly left and it just stays there until it
slows down even more. By 160kph it really wants to drop a wing, either wing, and by 150kph it's rudder dance with
some quick moves to stay level even while climbing at 100% power -- I'm well into the stall but still have lift and
anyone who thinks you lose ALL lift in the stall just go check that again, the lift curve doesn't stop at the top.

Two torque sources separated side to side do cancel in some ways and do not completely in others, just BTW.

so the troll was not actually a troll, and there IS torque on the 38?

more food for thought... </div></BLOCKQUOTE>

When you leave out the complete text of what I wrote then it *almost* says what you want, yes.


http://findarticles.com/p/arti...307/ai_n9283659/pg_2 (http://findarticles.com/p/articles/mi_qa3897/is_200307/ai_n9283659/pg_2)

Where the aircraft really came into its own was in performing stalls. The counter-rotating propellers kept the aircraft pointing straight ahead, so there was no torque effect to require rudder input as the speed decreased. Stalls demonstrated a good, early buffet warning, and no wing dropping occurred at the stall, even with small, pilot-applied aileron and rudder inputs to try to irritate its lateral and/or directional attitudes near the stall. It was even more impressive to me when I performed single-engine stalls with one engine either windmilling or feathered. With one of the P-38's dual fins and rudders always in the slipstream of a live engine, a stall could be performed with little or no wing drop. It was a pilot's dream under the trying conditions of a single-engine approach and landing.

Yep, IL2 is not perfect. Who'da guessed. It's only close in this case. Boo-hooooo!


<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by M_Gunz:
Compared to the single engine planes I've done the lowest speed climbs with, the P-38J is near dead tame on need for
rudder to keep level.


it IS tame, i agree with you there...although the torque modeling for single engine types in game is completely undermodeled and token at that </div></BLOCKQUOTE>

You know this because? Surely not your extensive hands-on experience with WWII fighters?
I have some Roaring Glory videos where Ethel and Hinton make those planes look easier to fly than IL2.

Once again. IL2 like any PC combat flight sim is NOT Perfect. Which other is as good or better?

I really had to push the P-38J to get it to show a rats c_nt hair of torque. Quick, call the U.N.!

AndyJWest
07-22-2009, 05:30 AM
One way to decide for yourself whether the simulated P38 models torque effects or not is to fly single-engined. The asymmetric thrust needs to be trimmed out with rudder and aileron, and whether the other effects are there or not could be difficult to determine conclusively, but I'd say that they are. It is worth bearing in mind that the P38s mass distribution tends to damp out some of the effects you'd see in a single engined fighter, so they are quite subtle.

Flying single-engined at low speeds again shows the benign stall characteristics. Even forcing the wing on the dead-engine side to stall seems usually to be recoverable without too much difficulty, from what I can tell. It takes a real effort to spin in single-engined flight, though I did succeed in doing this inadvertantly by attempting to loop on one engine. The result was quite spectacular, but entirely recoverable by throttling back the engine, followed by a normal spin recovery.

If you want to see this, as well as single-engine handling close to the stall, download this track:

http://www.datafilehost.com/download-6e8bc36b.html

The slightly misjudged landing was almost entirely due to pilot error, though at these speeds, any throttle movement will produce quite a trim change, so take care on approach. Have fun! http://forums.ubi.com/images/smilies/25.gif

Daiichidoku
07-22-2009, 08:01 AM
Originally posted by M_Gunz:
When you leave out the complete text of what I wrote then it *almost* says what you want, yes.


i dont see what the complete text would alter, the game either has torque on the 38, or not



Originally posted by M_Gunz:
Yep, IL2 is not perfect. Who'da guessed. It's only close in this case. Boo-hooooo!

i only informed someone that lack of torque is not within the game engine, i did not make any mention of the game being perfect or not, i think perhaps YOU are the troll



Originally posted by M_Gunz:
You know this because? Surely not your extensive hands-on experience with WWII fighters?
I have some Roaring Glory videos where Ethel and Hinton make those planes look easier to fly than IL2.

its well-known that 38s could lose 109s in spiral climbs when speeds got to the point where the airframe would spin about the prop and stalling out for it

that doesnt happen in the game

also well-known is the effect of slamming the throttle forward on a corsair at low speed, the ship would roll about its prop from torque effect

that doesnt happen in the game


also, i think you should stop watching roaring glory videos and start watching videos that may help you "relax", you clearly need it



Originally posted by M_Gunz:
Once again. IL2 like any PC combat flight sim is NOT Perfect. Which other is as good or better?

once again, troll, i only informed someone that the game engine does not allow for lack of torque
why dont you just man up and say i was correct, and be glad you learned another fact about the game? is it that big a deal for you?



Originally posted by M_Gunz:
I really had to push the P-38J to get it to show a rats c_nt hair of torque. Quick, call the U.N.!

oh, nevermind, this shows that indeed, i was correct, and the 38 has torque

M_Gunz
07-22-2009, 09:06 AM
Originally posted by M_Gunz:
Is this torque, input hardware not being ==>exact<== or roundoff?

The part you left out. Ask about trolls again.



its well-known that 38s could lose 109s in spiral climbs when speeds got to the point where the airframe would spin about the prop and stalling out for it

That was 190's, there were four of them and only one account of it being done.

JtD
07-22-2009, 09:33 AM
I don't see torque effects on the P-38 in game. Any behaviour that indicates there is torque?

Daiichidoku
07-22-2009, 11:44 AM
Originally posted by M_Gunz:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by M_Gunz:
Is this torque, input hardware not being ==>exact<== or roundoff?

The part you left out. Ask about trolls again. </div></BLOCKQUOTE>

i didnt bother, as i thought this quote would address the above


Originally posted by Daii:
no wing dropping occurred at the stall, even with small, pilot-applied aileron and rudder inputs to try to irritate its lateral and/or directional attitudes near the stall.




Originally posted by M_Gunz:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">
its well-known that 38s could lose 109s in spiral climbs when speeds got to the point where the airframe would spin about the prop and stalling out for it

That was 190's, there were four of them and only one account of it being done. </div></BLOCKQUOTE>

i will find the 109 account(s) i spoke of later

why did you not mention anything about the corsair?
is it because you know the in game corsair will not do as it was known to do in terms of RL low speed torque, thus confirm what i said about in game torque being undermodeled?

JtD
07-22-2009, 12:16 PM
The wing drops at stall speed are not related to any torque in game. So where's torque on the P-38 modeled?

I know of nothing, P-38 is torque free.

Daiichidoku
07-22-2009, 12:20 PM
Originally posted by JtD:
I don't see torque effects on the P-38 in game. Any behaviour that indicates there is torque?

stall it and see, there IS wing drop when there should be none

actually, snap stall it, as a "controlled" stall leads to somersaults http://forums.ubi.com/groupee_common/emoticons/icon_rolleyes.gif

robtek1957
07-22-2009, 12:20 PM
@daiichidoku

FB game engine makes no allowances for contra-rotating props/no torque, as its based on original IL2 engine, which was intended for only one flyable, the IL2, hence no consideration was given to modeling a lack of torque


so the troll was not actually a troll, and there IS torque on the 38?


it IS tame, i agree with you there...although the torque modeling for single engine types in game is completely undermodeled and token at that


oh, nevermind, this shows that indeed, i was correct, and the 38 has torque


why did you not mention anything about the corsair?
is it because you know the in game corsair will not do as it was known to do in terms of RL low speed torque, thus confirm what i said about in game torque being undermodeled?

Please make up your mind.
1. you state there is no torque for the p-38
2. you state there is torque for the p-38
3. you change the subject to "not enough torque for single engine planes"
4. you state that you are proven right that there is torque modeled for the p-38, which you denied in your 1. post.
5. you switch to a different plane to prove that torque is undermodeled.

afaik the more realistic torque effects where softened with one of the first patches because of complaining users

AndyJWest
07-22-2009, 12:27 PM
Sorry to shout but WHY DON'T YOU ALL STOP ARGUEING AND FLY THE FRIGGIN THING! http://forums.ubi.com/images/smilies/winky.gif

If my wife was a spitfire, I'd cheat on her with a P38. http://forums.ubi.com/groupee_common/emoticons/icon_cool.gif

M_Gunz
07-22-2009, 12:34 PM
You can push a freaking glider into a spin if you try hard enough. The *slightest* bit of imbalance, the *tiniest*
bit of slip is all it takes when you push it hard enough and it's not a spin-proof design.

Like I wrote and quoted, is my stick *perfectly centered*? Is there some roundoff or digitization error?

Oh-oh-oh-noooes! IL2 is not PERFECT! 5% is not close enough!
The Corsair is not exactly by someones favorite chart! The 190 glass has no refraction!
Oh the SHAME! Quick, shoot yourself! The END is coming!

Quick, break out the TABLE DRIVEN SIMS! They ALWAYS meet the all-important chart numbers!
Who freaking CARES about handling when your very Nation and your virtual d!ck are at stake!

Run about, scream and shout! Twirl!

Daiichidoku
07-22-2009, 12:37 PM
Originally posted by robtek1957:
Please make up your mind.
1. you state there is no torque for the p-38
2. you state there is torque for the p-38
3. you change the subject to "not enough torque for single engine planes"
4. you state that you are proven right that there is torque modeled for the p-38, which you denied in your 1. post.
5. you switch to a different plane to prove that torque is undermodeled.

afaik the more realistic torque effects where softened with one of the first patches because of complaining users

1. please re-read the post, i stated "no allowance for contra-props/no torque", and " no consideration was given to modeling a lack of torque"
2. yes
3. please re-read the post, i replied to M.Gunz bringing up single-engine types:"Compared to the single engine planes I've done the lowest speed climbs with, the P-38J is near dead tame on need for rudder to keep level."
4. read 1. above
5. yourself and M.Gunz first mentioned different types, i only responded about them in kind

Daiichidoku
07-22-2009, 12:45 PM
Originally posted by M_Gunz:
You can push a freaking glider into a spin if you try hard enough. The *slightest* bit of imbalance, the *tiniest*
bit of slip is all it takes when you push it hard enough and it's not a spin-proof design.

Like I wrote and quoted, is my stick *perfectly centered*? Is there some roundoff or digitization error?

Oh-oh-oh-noooes! IL2 is not PERFECT! 5% is not close enough!
The Corsair is not exactly by someones favorite chart! The 190 glass has no refraction!
Oh the SHAME! Quick, shoot yourself! The END is coming!

Quick, break out the TABLE DRIVEN SIMS! They ALWAYS meet the all-important chart numbers!
Who freaking CARES about handling when your very Nation and your virtual d!ck are at stake!

Run about, scream and shout! Twirl!



again, i only mentioned that a lack of torque is not written into the game engine, you cant seem to accept that fact

M_Gunz
07-22-2009, 01:03 PM
Since I don't know the source code for IL2 and I seriously doubt that you do either I don't accept your 'fact'.

I'm sure that the 2 engines in the P-38 that both run exactly the same and produce exactly negating effects to
each other IRL always and forever. It must since real pilots said so! Not just freaking CLOSE but ABSOLUTE.

I ran the thing at 100% in a steep climb down to 180kph on the speedbar HANDS OFF with NO RUDDER TRIM, only pitch.
That may not be good enough for you but then wtf is?

JtD
07-22-2009, 01:37 PM
Originally posted by Daiichidoku:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by JtD:
I don't see torque effects on the P-38 in game. Any behaviour that indicates there is torque?

stall it and see, there IS wing drop when there should be none

actually, snap stall it, as a "controlled" stall leads to somersaults http://forums.ubi.com/groupee_common/emoticons/icon_rolleyes.gif </div></BLOCKQUOTE>

And like I said the wing drop is not related to torque. So if you base your entire case on the wing drop, you can drop the case.

Turn engines off, feather prop, no torque, any plane, and it drops a wing at stall. Not torque related, nothing special with the P-38.

So, is there any torque modeled with the P-38?

BillSwagger
07-22-2009, 01:38 PM
if i may chime in, I'm not sure of the exact context of the argument on lack of torque effects, but.....


the 'fact' is, when i take off in a single engine plane, i have to rudder pretty heavily to the right, even with a locked tail wheel, or I would end up rolling off to the left side of the runway.

In flight, if i don't trim rudder, then i would also experience a roll to the left, if i center my stick.

When i'm landing, and leveling my plane on approach, sometimes i'm coming in short, so i kick throttle up from 20% to 40%, and that alone will cause my plane to roll to the left.

I've never actually flown a real WW2 plane, so i couldn't say for certain if the torque effects are under-modeled or over-modeled.
It does seem to be more prevalent in some planes than others, but that also has to do with the power plant in respect to the weight of the plane.


In the game, common sense tells me to roll with the torque out of stall. Rolling opposite torque is more likely to lead to a spin, me thinks....

As for the P-38, i don't think lack of torque is a flaw.
The plane can drop a wing for a variety of different reasons related to wind/turbulence and the degree of the stall over different sections of the wing.

na85
07-22-2009, 02:08 PM
IL2's stall modeling isn't very accurate. I remember Ecodragon posting a long time ago about how it's nearly impossible to fly the plane into a straight stall, the aircraft almost always drops a wing.

BillSwagger
07-22-2009, 02:23 PM
actually its quite easy if you tighten up prop pitch to 40-50% as the plane slows down. I can hang a P-47 by its nose until its falling backwards. The speed bar reads -10...-20....-30...


I still agree with the limited stall modeling, but its sill much better than other multiplayer sims.

Daiichidoku
07-22-2009, 05:24 PM
suck on this M.Gunz:

http://forums.ubi.com/eve/foru...283/m/5691013592/p/3 (http://forums.ubi.com/eve/forums/a/tpc/f/23110283/m/5691013592/p/3)



Originally posted by Gibbage1:
You know the P-38 has my attention big time.

Most of the issues we complain about has to do with the engine limitations. When Oleg made IL2, he was only going to have the IL2 flyable and did not program any extentions for many of the functions the P-38 needs.

#1, multi-engine support. This was "hashed" in for FB, but its still not 100%.

#2, He never thought he would have a P-38 in the game, so he never built the engine to support torque.

#3, High alt performance is a BIG issue.

From what I understand, all aircraft in IL2 are given values, and use those values to fly in the same world govern by the same rules. Thats why every patch seams to change every aircraft. Something in the world changed. Weather it be gravity, air density or whatever variables Oleg has. So all aircraft fallow the same set of rules. All aircraft have torque (some more then others). During the beta of AEP, this was one of my bug writeups but Oleg said he would not give the P-38 no torque because of limitations of the engine. But he did say BoB will not have this limitation. We can only hope that adding BoB's FM into IL2 is going to help. I think it will since the only real possible way to make all aircraft fallow BoB's FM is to make the world fallow BoB's rules.

Personally I am excited to see how differant the FM will be. I hope the P-38 no longer goes into compressability at low altitudes (again, limit of FM) and I hope there are more then the standard "snap" stall in the global FM. I also hope high altitude performance is simulated well in the new FM. I hope the engine can calculate the extra air moving over the flaps from the prop wash, making them more effective. All these things will help the P-38. But you still wont turn fight a Zero in it http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif

deepo_HP
07-22-2009, 07:41 PM
Originally posted by Daiichidoku:
suck on this M.Gunz:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Gibbage1:
Oleg said he would not give the P-38 no torque because of limitations of the engine. </div></BLOCKQUOTE>is that supposed to be an official statement from developer's side?
i am probably just too silly, but what limitation should there be to not being able not to implement something? the more, if it is something i still have no clue how to get the experience of.

why wouldn't you just offer a track, where you demonstrate the non-lacking torque, pls?
would help me at least... and could be analysed with devicelink.
that way you could easily show, that there is no other factor but torque, which leads to the described stall-behaviour.

na85
07-22-2009, 07:49 PM
ntrks or it didn't happen

M_Gunz
07-22-2009, 08:15 PM
Originally posted by na85:
IL2's stall modeling isn't very accurate. I remember Ecodragon posting a long time ago about how it's nearly impossible to fly the plane into a straight stall, the aircraft almost always drops a wing.

Prior to 4.x you could not hold a stall, it was impossible and there was a very good thread about just that around 3.2.

I can climb planes down at stall speed though it gets very tricky at the lowest speeds I can maintain. 140 kph in both
P-40B and 109G-6 for instance and as low as 150 kph in P-38J, it's a LOT easier with the P-38 as I barely need to touch
rudder on that while the others I have to hold quite a bit though NONE of them are steady at those speeds and all need
some dancing around from time to time.

Go ahead, see how slow you can climb at 100% power and then what you get for power-idle stall. Power off clean stall
for the 109G-6 tests to about 150 kph on the speedbar but power on it climbs at 140 kph on the speedbar. Is that
good enough? Critical AOA and all that, nein?

M_Gunz
07-22-2009, 08:39 PM
Yeah, Gibbage who knows all and interprets with complete understanding, but not as good as he spells, taking Olegish
and turning it into whatever he wants.

Two engines and both have torque when IRL there was none, right? Suck it yourself, you've done such a good job so far.

IRL both engines always ran exactly equal and opposite I suppose. Well yes they can be extremely close with an expert
pilot adjusting them both. I suppose you do that in game and know just how? Does your chair move to tell you balance?

IRL two widely separated torque sources will always cancel out under all conditions too? If you say yes then you agree
with physical impossibilities but WTH when you have words from actual pilots to interpret into your own absolute, down
to 5+ decimal places fantasy-reality then it's up to sim developers to support your "vision".

Your bait is stale, it's dead horse material. What you want is an on-rails table-driven FM that lets anyone fly to the
limits and sometimes beyond using any hardware they choose since only then will folks like you be happy. Go play CFS,
it's probably close enough using the 1% models.

BillSwagger
07-22-2009, 08:46 PM
Originally posted by na85:
ntrks or it didn't happen


http://www.filefront.com/14102591/P-38Lstall.zip

straight up P-38 stall...two in a row...

M_Gunz
07-22-2009, 08:48 PM
Originally posted by deepo_HP:
why wouldn't you just offer a track, where you demonstrate the non-lacking torque, pls?
would help me at least... and could be analysed with devicelink.
that way you could easily show, that there is no other factor but torque, which leads to the described stall-behaviour.

I can give track with wing drop, even a tiny, dust mote bit more. To this one that is all that matters.
Fact is we have two engines modeled with torque in complex floating-point equations that simply will not
always come out exactly-exactly equal and opposite. Push it hard enough and the difference will show.
From there it's a short hop to slapping on a label and making manure sculptures to honor such insight.

na85
07-22-2009, 11:31 PM
Originally posted by BillSwagger:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by na85:
ntrks or it didn't happen


http://www.filefront.com/14102591/P-38Lstall.zip

straight up P-38 stall...two in a row... </div></BLOCKQUOTE>

nice

deepo_HP
07-22-2009, 11:48 PM
hi m_gunz,

that is more or less what i experience. but i am not very good in testing.
that is why i would like to see, what is considered to be a wing-drop for the reason of a flawed torque-model. imo, the effect of counterrot props is very characteristic in the p-38 and so i am curious, what other expectations there are.


hi billswagger,

thx for the tracks. have to watch later again, i am doing snake-eyes right now.

M_Gunz
07-23-2009, 12:03 AM
what is considered to be a wing-drop for the reason of a flawed torque-model

I can show wing drop at very high AOA and very low speed.
I don't consider it being due to a flawed torque model, you have to get _that_ part from someone else.

To me it looks like a very slight imbalance, possibly in my hardware or miniscule round-off difference
in the FM but that's because it's so freaking <==small==> as to be almost non-existent in that it only
shows up in a very extreme situation where any of those could easily explain what happens.

I know that there are planes than can't spin. They are also useless as fighter designs.

BillSwagger
07-23-2009, 12:54 AM
It might be your controls, cause i dont see any torque in a stall. It whips to one side or the other, and it does this randomly, then it plops back into the envelope very quickly.

I also took the time to run each engine separately, and the plane rolls opposite to the rotation of the prop. So if the right engine is off, the right side dips. This can be because of added drag or torque. I did the same with the left engine, feathering it, and the left side dipped.

Here is the interesting part. When i kick back on the engine the wing hops up, almost like you can feel the engine rpms winding up then the torque keeps the wing in place.

So the torque is there, and its reasonable to think that if the torque isn't exactly even then you might notice an effect.

JtD
07-23-2009, 08:51 AM
Originally posted by BillSwagger:

straight up P-38 stall...two in a row...

Straight up stall don't happen. You don't need any lift when going straight up, so you don't need to pull any angle of attack and so the plane won't stall. Stall is not about going slow.

M_Gunz
07-23-2009, 12:24 PM
Originally posted by BillSwagger:
It might be your controls, cause i dont see any torque in a stall. It whips to one side or the other, and it does this randomly, then it plops back into the envelope very quickly.

I also took the time to run each engine separately, and the plane rolls opposite to the rotation of the prop. So if the right engine is off, the right side dips. This can be because of added drag or torque. I did the same with the left engine, feathering it, and the left side dipped.

Here is the interesting part. When i kick back on the engine the wing hops up, almost like you can feel the engine rpms winding up then the torque keeps the wing in place.

So the torque is there, and its reasonable to think that if the torque isn't exactly even then you might notice an effect.

Most of what you call torque is propwash which being spiral in nature and acting primarily on wings and tail does
torque the plane. Propwash also keeps airflow going over the wings even when the plane is moving slower which is
maybe most (not all) of why you see the wing drop on engine cut and pick up on the restart.

JtD got a good spot on you with the straight up stalls! But still at the zero airspeed point any torque should show
and IMO more clearly than in a stall condition. http://forums.ubi.com/images/smilies/16x16_smiley-wink.gif

BillSwagger
07-23-2009, 01:38 PM
What is it called when you nose up to the point where the plane no longer moves, hangs, and might even begin to fall backwards, before it flips nose down again?

I've come to think that a stall means that air is no longer moving over the wing to produce lift.


stall is not about going slow
You might need to rephrase that.
It is not limited to just going slow, you can increase the angle of attack or the load factor, and both can stall the wing even if you are moving relatively fast.

M_Gunz
07-23-2009, 01:48 PM
Not Stall. Stall is about Angle of Attack (air over the wing) exceeding the critical angle for the wing.

ADD: Definition and details about stall. (http://www.av8n.com/how/htm/vdamp.html#sec-stall-intro)



* The stall occurs at the critical angle of attack.
* The critical angle of attack is the point where further increases in angle of attack do not result in a further increase in coefficient of lift.
* The unstalled regime refers to angles of attack below the critical angle of attack; the stalled regime refers to angles of attack beyond the critical angle of attack.




5.3.2 Flying Beyond the Stall?

We are now in a position to answer a question that used to cause a lot of confusion: can you fly “beyond” the stall? Some people say yes, some people say no. The answer depends on whether you mean “beyond” the stalling angle of attack, or “beyond” the stalling airspeed. That is,

* Yes, it is definitely possible to fly at an angle of attack higher than the critical angle of attack. (It may require super-human skill to overcome the pathological handling characteristics in this regime, but it is possible in principle to maintain a stalled angle of attack indefinitely.)
* No, it is not possible to sustain flight at an airspeed below the stalling speed.


Read more at the site, there's pictures that help out for one.

If you're not sure about the site then find the part with Denker's credentials which are very impressive.

BillSwagger
07-23-2009, 01:51 PM
so should i say "i climbed nose up until this annoying little beepy thing goes off, oh yeah, and my airplane began falling backwards." http://forums.ubi.com/images/smilies/59.gif http://forums.ubi.com/groupee_common/emoticons/icon_smile.gif

i know i'm being facetious, but its sort of like correcting my grammer, when over looking the point of what i was showing.

(that a P-38 can be flown straight up into zero or negative airspeed, with no disruption from torque)

M_Gunz
07-23-2009, 02:03 PM
Did you bother reading where I wrote "But still at the zero airspeed point any torque should show
and IMO more clearly than in a stall condition."?

BillSwagger
07-23-2009, 02:07 PM
yes... http://forums.ubi.com/images/smilies/halo.gif
wasn't directing that at you, sir.

Stall is a loose term when describing aircraft behavior.

When describing airfoil designs it takes on a more technical definition. http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif

M_Gunz
07-23-2009, 09:34 PM
The FAA includes other words with Stall in the regs for manufacturers to determine Reference Stall Speed Clean and Dirty.
The actual loading of the plane has to be included, no trim changes, the way that power is dropped and how the plane is
to approach the stall. That's when it gets technical! They have to or the makers will cut corners left and right.

Anyway I stuck that link in so you could get a nice bit of filling in. Denker is an FAA safety guy and that site is for
RL pilots to pick up on what keeps them alive. Consider that RL flying dangers are taken far more seriously than the
average gamer looking for brag rights gets. The RL approach is just the starting point for _simulating_ what it was to
be a fighter pilot as opposed to the air quake players.

JtD
07-24-2009, 11:23 AM
Over looking and not addressing are two pairs of shoes. For me the torque on the P-38 topic is pretty much settled. Haven't seen any indication of it being present so far. What's more to say?

Certainly didn't mean to annoy you.

deepo_HP
07-25-2009, 07:55 PM
Originally posted by M_Gunz:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">what is considered to be a wing-drop for the reason of a flawed torque-model

I can show wing drop at very high AOA and very low speed.
I don't consider it being due to a flawed torque model, you have to get _that_ part from someone else. </div></BLOCKQUOTE>i haven't replied to you at all with my wish for a track... and i also never to anything you said about flawed torque model. of course i got it from someone else - whom i replied to in first order.

M_Gunz
07-25-2009, 08:40 PM
I think there's only one person in this thread who really thinks the IL2 P-38s show torque.