PDA

View Full Version : Back to Spitfire dive-speeds



SkyChimp
03-25-2004, 08:54 PM
In a previous thread, excerpts from a British test to determine high speed characteristics was posted. That test compared the Spitfire MK XI and the Mustang I (an Allison engined variant). The test showed that the Spitfire was capable of diving to mach .891, a very high mach number. The explanation was offered that the reason this was possible was because the Spitifire had wings more suited to high-speed flight than the Mustang, and as a result drag rose more slowly than it did on the Mustang. The report contained a table that showed the zero-lift drag coefficients for the Spitfire MK XI at various mach speeds:

http://members.cox.net/us.fighters/table.jpg

In chart form, it looks like this. The Mustang I results are included as well:

http://members.cox.net/us.fighters/spitfiredrag.jpg

You can see that at higher mach speeds, the Spitfire seems to resist a rise in drag very well.

The P-51 Mustang was arguably the "cleanest" prop fighter of WWII as evidenced by its low Cd0 at moderate speeds. By comparison, the Spitfire seemed "dirtier" evidenced by a higher Cd0 at moderate speeds.

I perused a NACA report on the high-speed characterisitics of the P-51B airplane derived from wind-tunnel testing of a model, and dives of the actual plane. Wind-tunnel tests and dive test produced virtually identical results. The NACA test results showed that drag was, indeed, low at moderate speeds. But at about mach .72, the drag began to rise sharply. You can see it in this NACA chart. The Cd0 line is highlighted in red:

http://members.cox.net/us.fighters/p51bdrag.jpg

I found it surprising that the Mustang was "draggier" at high speeds than was the Spitfire, despite the fact that it had a very clean fuselage and NACA NAA low-drag laminar flow airfoils, versus the conventional airfoils of the Spitfire. But the explanation was offered that the Spitfire's wings were thinner, thus more suited to high-speed flight. No doubt, the Spitfire's wings are thinner than the Mustang's - 13% versus 16% respectively. I've also been told that laminar flow wings are only more efficient than conventional wings of the same thickness. So, the Spitfire had wings more suited to high-speed flight than did the Mustang - because they were thinner.

The P-51B is generally recognized as the "cleanest" of the Mustang series due mainly to its high back and efficient radiator scoop design. But somehow, the British got better Cd0s for the Mustang I than the NACA did for the P-51B. How is that?

I perused another NACA report on the high-speed characteristics of another WWII era plane that had a lower Cd0 than even the Mustang, and that had wings of the same thickness as the Spitfire - the P-80A. The results of this test were obtained by wind-tunnel testing a 1/3 scale model and flight testing the real thing. Virtually identical results were produced.

Here is a chart showing the drag coefficients of the P-80A at zero-lift - highlighted in red:

http://members.cox.net/us.fighters/p80adrag.jpg

The P-80A had a very low Cd0 at moderate mach speeds. But like the Mustang, it experienced a sharp increase in drag at about mach .75.

I superimposed the Cd0 lines from the NACA Mustang and P-80A tests onto the chart for the Spitfire MK XI. Low and behold, the Spitfire has an even lower drag coefficient than the P-80A at mach speeds over about mach .835.

http://members.cox.net/us.fighters/dragcompare.jpg

How is that? It's easy to buy the argument that the Spitfire was more suited to high speed flight than was the Mustang because it had thinner wings. But the P-80A had wings of equal thickness, 13%, and additonally they were NACA low-drag laminar flow airfoils, with swept leading edges. How in the world can the Spitfire MK XI have a lower drag coefficient at mach .835 and above than the P-80A?

In 1942 and 1943 incredible accounts were coming from pilots who claimed to have dived to speeds near, or even in excess of, mach 1. Thunderbolt designer Alexander Kartveli claimed his plane could dive to mach .92. But Lockheed's Kelly Johnson stated he found the reason for such claims. He stated that the use of pitot measuring devices were giving false data. "The reason they saw this false data on the cockpit insturments was very simple. It had to do with the fact that the static system was generally hooked to a pitot tube and had a substantial delay in it reading in a dive, giving false values of the air-speed indicator, altimeter, rate-of-climb indicator, and the lines themselves could not vent fast enough to measure true static pressure in a screaming dive." (Source: Republic's P-47 Thunderbolt: From Seversky To Victory).

Additionally, Herbert Fisher, former Curtiss-Wright Chief Test Pilot and PhD of Aeronautics said, "No WWII propeller-driven aircraft even came close to reaching mach 1.0 in a dive, due to the astronimical drag rise of the propellor shortly after exceeding approximately mach .83." (Source: same)

I'm not sure if the speeds achieved by the Spitfire MK XI in that test were recordered by cockpit insturments hooked to a pitot or not, but it seems that -may- be the case. The Cd0s were likely calculated based, in part, on dive performance. And AFAIK, the Spitfire in that test had a typical production prop.

So, was there an error in the test? If there was an error in speed readings, does that throw off the Cd0s?

Or did that Spitfire really perform as well as stated? And if so, what was it about the Spitfire that made it so much more suited for high speed flight than even the P-80A jet(which had equally thick wings or laminar flow design)?

I'm fully aware that these questions will not be settled, but I'd like to hear some opinions anyway.

Regards,
SkyChimp
http://members.cox.net/us.fighters/skychimp.jpg

SkyChimp
03-25-2004, 08:54 PM
In a previous thread, excerpts from a British test to determine high speed characteristics was posted. That test compared the Spitfire MK XI and the Mustang I (an Allison engined variant). The test showed that the Spitfire was capable of diving to mach .891, a very high mach number. The explanation was offered that the reason this was possible was because the Spitifire had wings more suited to high-speed flight than the Mustang, and as a result drag rose more slowly than it did on the Mustang. The report contained a table that showed the zero-lift drag coefficients for the Spitfire MK XI at various mach speeds:

http://members.cox.net/us.fighters/table.jpg

In chart form, it looks like this. The Mustang I results are included as well:

http://members.cox.net/us.fighters/spitfiredrag.jpg

You can see that at higher mach speeds, the Spitfire seems to resist a rise in drag very well.

The P-51 Mustang was arguably the "cleanest" prop fighter of WWII as evidenced by its low Cd0 at moderate speeds. By comparison, the Spitfire seemed "dirtier" evidenced by a higher Cd0 at moderate speeds.

I perused a NACA report on the high-speed characterisitics of the P-51B airplane derived from wind-tunnel testing of a model, and dives of the actual plane. Wind-tunnel tests and dive test produced virtually identical results. The NACA test results showed that drag was, indeed, low at moderate speeds. But at about mach .72, the drag began to rise sharply. You can see it in this NACA chart. The Cd0 line is highlighted in red:

http://members.cox.net/us.fighters/p51bdrag.jpg

I found it surprising that the Mustang was "draggier" at high speeds than was the Spitfire, despite the fact that it had a very clean fuselage and NACA NAA low-drag laminar flow airfoils, versus the conventional airfoils of the Spitfire. But the explanation was offered that the Spitfire's wings were thinner, thus more suited to high-speed flight. No doubt, the Spitfire's wings are thinner than the Mustang's - 13% versus 16% respectively. I've also been told that laminar flow wings are only more efficient than conventional wings of the same thickness. So, the Spitfire had wings more suited to high-speed flight than did the Mustang - because they were thinner.

The P-51B is generally recognized as the "cleanest" of the Mustang series due mainly to its high back and efficient radiator scoop design. But somehow, the British got better Cd0s for the Mustang I than the NACA did for the P-51B. How is that?

I perused another NACA report on the high-speed characteristics of another WWII era plane that had a lower Cd0 than even the Mustang, and that had wings of the same thickness as the Spitfire - the P-80A. The results of this test were obtained by wind-tunnel testing a 1/3 scale model and flight testing the real thing. Virtually identical results were produced.

Here is a chart showing the drag coefficients of the P-80A at zero-lift - highlighted in red:

http://members.cox.net/us.fighters/p80adrag.jpg

The P-80A had a very low Cd0 at moderate mach speeds. But like the Mustang, it experienced a sharp increase in drag at about mach .75.

I superimposed the Cd0 lines from the NACA Mustang and P-80A tests onto the chart for the Spitfire MK XI. Low and behold, the Spitfire has an even lower drag coefficient than the P-80A at mach speeds over about mach .835.

http://members.cox.net/us.fighters/dragcompare.jpg

How is that? It's easy to buy the argument that the Spitfire was more suited to high speed flight than was the Mustang because it had thinner wings. But the P-80A had wings of equal thickness, 13%, and additonally they were NACA low-drag laminar flow airfoils, with swept leading edges. How in the world can the Spitfire MK XI have a lower drag coefficient at mach .835 and above than the P-80A?

In 1942 and 1943 incredible accounts were coming from pilots who claimed to have dived to speeds near, or even in excess of, mach 1. Thunderbolt designer Alexander Kartveli claimed his plane could dive to mach .92. But Lockheed's Kelly Johnson stated he found the reason for such claims. He stated that the use of pitot measuring devices were giving false data. "The reason they saw this false data on the cockpit insturments was very simple. It had to do with the fact that the static system was generally hooked to a pitot tube and had a substantial delay in it reading in a dive, giving false values of the air-speed indicator, altimeter, rate-of-climb indicator, and the lines themselves could not vent fast enough to measure true static pressure in a screaming dive." (Source: Republic's P-47 Thunderbolt: From Seversky To Victory).

Additionally, Herbert Fisher, former Curtiss-Wright Chief Test Pilot and PhD of Aeronautics said, "No WWII propeller-driven aircraft even came close to reaching mach 1.0 in a dive, due to the astronimical drag rise of the propellor shortly after exceeding approximately mach .83." (Source: same)

I'm not sure if the speeds achieved by the Spitfire MK XI in that test were recordered by cockpit insturments hooked to a pitot or not, but it seems that -may- be the case. The Cd0s were likely calculated based, in part, on dive performance. And AFAIK, the Spitfire in that test had a typical production prop.

So, was there an error in the test? If there was an error in speed readings, does that throw off the Cd0s?

Or did that Spitfire really perform as well as stated? And if so, what was it about the Spitfire that made it so much more suited for high speed flight than even the P-80A jet(which had equally thick wings or laminar flow design)?

I'm fully aware that these questions will not be settled, but I'd like to hear some opinions anyway.

Regards,
SkyChimp
http://members.cox.net/us.fighters/skychimp.jpg

WWMaxGunz
03-25-2004, 08:59 PM
Near and at transsonic speeds aerodynamics change.
That's why.


Neal

SkyChimp
03-25-2004, 09:10 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by WWMaxGunz:
Near and at transsonic speeds aerodynamics change.
That's why.


Neal<HR></BLOCKQUOTE>

Do you think you can come up with a better reason than that?

Regards,
SkyChimp
http://members.cox.net/us.fighters/skychimp.jpg

WWMaxGunz
03-25-2004, 09:28 PM
I'm not going to get into a discussion about it in your style. The reading I've done went farther into those matters than I can deeply pursue to your beat it to death methods of debate. Get someone else to explain it. I can only say that with compression and shockwaves the dynamics change. At supersonic speeds the rules change upside down is the term I've read for that but transsonic speeds has changes from lower speeds. Transsonic speed depends on the design of the actual plane, btw, so don't go saying a set mach value is some kind of line to judge all planes by. I'm guessing that the P-51 line comes sooner than the Spit XIV line, but that's a guess as I'm not a freaking AE. Are you?


Neal

SkyChimp
03-25-2004, 09:31 PM
Given your immediate insults, I'd say you're right, this isn't the thread for you.


Regards,
SkyChimp
http://members.cox.net/us.fighters/skychimp.jpg

Ugly_Kid
03-25-2004, 10:59 PM
1) Laminar flow profile is not good for everything, depends on Reynold's number and conventional turbulent flow is not that allergic to separation as laminar. The shockwaves do cause boundary layer separation.

2) Wing planform, (not only sweep but also aspect ratio and area has effect in compressible flow). Also, here you compare CD0 although wings have different areas. This gives one tendency of drag build-up but not a deeper view of the drag itself. Also P-80 may have swept leading edge (spitfire eventually even more http://ubbxforums.ubi.com/infopop/emoticons/icon_smile.gif) but it still has ~straight 25% chord line.

3) Spitfire values seem to be from the test posted by hop2002. This means not windtunnel. The prop thrust, for example is an estimated value and has a great effect on the outcome of CD0 which is also just a calculated value. Both of the NACA curves are obtained in windtunnel with model.

Now, I don't know where you want to get with that. One curve or another the limiting factor in P-something dives were not drag but stability and controllability. Spitfire was one of the worst diving fighters of that era (acceleration) but it is throughoutly possible that it was controllable to a higher Mach number than many others. It may not have been also the most rugged design but at a higher altitude shown by hop's documents the aerodynamic forces at high Mach low EAS (or we say very low density high TAS)are not necessarily superior to less impressive SL values. Higher alt and the same Mach will not make P-something more controllable though.

It's funny to write something being possible about spitfire and not necessarily outdated and not even being a Spitfire afficianado myself. In current preferences I take P-51 any given day and P-38 to look cool.

faustnik
03-26-2004, 12:19 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by WWMaxGunz:
I'm not going to get into a discussion about it in your style. The reading I've done went farther into those matters than I can deeply pursue to your beat it to death methods of debate. Get someone else to explain it. I can only say that with compression and shockwaves the dynamics change. At supersonic speeds the rules change upside down is the term I've read for that but transsonic speeds has changes from lower speeds. Transsonic speed depends on the design of the actual plane, btw, so don't go saying a set mach value is some kind of line to judge all planes by. I'm guessing that the P-51 line comes sooner than the Spit XIV line, but that's a guess as I'm not a freaking AE. Are you?


Neal<HR></BLOCKQUOTE>


Yeah SkyChimp, WTF are you thinking asking a question like that here? Stop asking questions about airplanes!

http://ubbxforums.ubi.com/images/smiley/crazy.gif

http://pages.sbcglobal.net/mdegnan/_images/FaustSig
www.7Jg77.com (http://www.7jg77.com)
CWoS FB forum. More Cheese, Less Whine. (http://www.acompletewasteofspace.com/forum/viewforum.php?f=25)

WWMaxGunz
03-26-2004, 02:20 AM
No faustnik, you're NOT EVEN CLOSE, as usual.

I gave what I knew cleanly enough and refuse to get sucked into a debate about it.

The questions are good. They beat the crap out of a lot of others posted. And as far as people going around sniping at every opportunity and the little finger by the head icon... I rate that as low and the crazy one is the one with the obsession here. Get some rest maybe.


Neal

Nexus2005
03-26-2004, 06:03 AM
Right, i'm a complete noob in these matters, but in a nutshell does this mean the spit should be able to dive more than 700kph without falling to bits in the game?

http://www.bobcs.co.uk/sig/Nexussig/sig2.jpg (http://www.bobcs.co.uk)

TooCool_12f
03-26-2004, 06:04 AM
i fyou check your chart about drag at high speeds, you'll notice that the thunderbolt is much worse than the spit.. and still, it could outdive it by a fair margin...

at some point the weight can't explain it all... My guess would be that spits instruments were giving a false reading during tests (above certain speed) http://ubbxforums.ubi.com/infopop/emoticons/icon_wink.gif

Arm_slinger
03-26-2004, 06:19 AM
The Spit wing can reach a speed of Mach 1.3 before it falls apart. The limiting factors was the prop (which sheared off when they tested this), and the tail. I dont know what effects happened on the tail

T4T recruitment officer

Sim lover?, want something new? Then look at "Target for Tonight the definitive night bombing simulation ever, featuring the RAF's Bomber Command.

Got you interested? Look for us here: www.nightbomber.com/forums (http://www.nightbomber.com/forums)

Nexus2005
03-26-2004, 06:23 AM
Right, so it should be able to go much faster then. Hope it gets fixed http://ubbxforums.ubi.com/infopop/emoticons/icon_smile.gif

http://www.bobcs.co.uk/sig/Nexussig/sig2.jpg (http://www.bobcs.co.uk)

BerkshireHunt
03-26-2004, 09:07 AM
[QUOTE]Originally posted by Ugly_Kid:
(The Spitfire) "may not have been also the most rugged design."

I don't want to hijack this thread but I feel the need to put the record straight on this one. The last thread concerning the Spitfire's dive speed was contaminated by Isegrim/Kurfurst's poison pen regarding the Spitfire's structural integrity and I see his contention that it was 'weak' is gaining currency here- which is just what he intended.

I thought I remembered reading an interview on this subject many years ago- and finally found it in a yellowed copy of Alfred Price's 'Spifire At War' (published 1974). It's germane to this discussion (as my teacher used to say) because the person being interviewed is none other than Mr Eric Newton who spent the war with the Air Accident Investigation Branch. He was still employed by them as an investigator in 1974- the time of the interview- so presumably still had the facts at his fingertips. This body was, and is, independent of the RAF.
Mr Newton was called in to investigate Spitfire crashes which could not be immediately attributed to pilot error (the same crashes which are detailed in Morgan and Shacklady). He says:

"Out of a total of 121 serious or major accidents to Spifires reported to us between the begining of 1941 and the end of the war, 68 involved structural failure in the air. Initially the most common reason for such failures, with 22 instances in 1941 and 1942, was aileron instability. The symptoms were not at all clear cut: the aircraft were usually diving at high speed when they simply fell to pieces. Only after one of the pilots had survived this traumatic experience and parachuted successfully were we able to find the cause. During his dive he saw both of his ailerons suddenly flip up, producing an extremely violent pitch- up which caused the wing to fail and the aircraft to break up. In collaboration with RAE we did a lot of tests and found that aileron up- float was made possible by stretch in the control cables; in those days tensioning was a hit or miss affair with no compensation for temperature. On our recommendation the RAF introduced a tensometer which ensured accurate tensioning of the controls; this, and the simultaneous introduction of metal surfaced ailerons ('42/'43), cured almost all the cases of aileron instability in the Spitfire.
The next most serious cause of structural failure in the Spitfire was pilots overstressing the airframe. She was extremely responsive on the controls and one must remember that in those days there was no accelerometer to tell the pilot how close he was to the limit. So it was not difficult to exceed the aircraft's 10G ultimate stress factor (what was the 109's?- Berkshire) during combat or when pulling out from a high speed dive; during the war we were able to put down 46 major accidents to this cause, though undoubtedly there were many other occasions when it happened and we did not see the wreckage. Incidentally, if there was a structural failure in the Spitfire it was almost inevitably the wing that went; the fuselage was far less likely to fail first (the same for most low wing monoplane fighters?-except the Typhoon?- Berkshire).
I once asked a very senior RAF officer why the accelerometer- technically a simple instrument- was not introduced during the war. He replied that he was sure it would have an adverse effect on the fighting spirit of the pilots (same was said re the parachute in WW1!- Berkshire).
Whether that would have been so I cannot say. But I do know that when they finally introduced the accelerometer into service in the Hunter in 1954, and began educating the pilots on structural limitations and the dangers of overstressing, accidents to this cause virtually ceased.
After structural failure the next largest category of accidents proved on investigation to have followed loss of control by the pilot (36 cases). Of these 20 occured in cloud and could be put down to pilot error; one must remember that in the rush to get pilots operational instrument training was not up to peacetime standards. A further 13 accidents were shown to have been caused by oxygen starvation; the oxygen system had been used incorrectly with the result that the pilot had passed out and the aircraft had crashed. As a result of our investigations the system was modified to make it easier to operate.
The remaining 3 accidents in the loss of control category were initiated by the pilot pulling excessive G and blacking himself out.
Engine failures and fires contributed a further 17 accidents, and the remainder could be put down under the 'miscellaneous' heading (long story here about fuel leaks and explosions on the ground- Berkshire)
As I have mentioned we investigated a total of 121 Spitfire accidents during the war. The causes did not always fit simply into neat categories mentioned above. For example, a pilot might lose control in cloud and his aircraft then broke up in the ensuing dive due to aileron instability- in that case the accident would have been listed under two categories. There were one or two accidents caused by the light- weight plastic bucket seats fitted to some batches of Spitfires. The trouble was they were not strong enough and if there was a heavy pilot who pulled a bit of G they tended to collapse- on to the elevator control runs which ran underneath. We soon had that type of seat replaced.
In the nature of my work I tend to concentrate on an aircraft's failings and ignore its good points; but how safe was the Spitfire? I think the figures speak for themselves; a total of more than 22,000 were built, and we were called in on only 130 occasions- and in not all of those was the Spitfire at fault. If one considers that she was not a simple trainer built for ease of handling, there can be no doubt that the Spifire was a remarkably safe little aircraft."

To summarise:
There were 121 Spitfire crash investigations between 1941 and May 1945 involving serious structural failure:
22 aileron instability
46 pilot overstressed airframe
20 pilot error in cloud
13 misuse of oxygen system- pilot error
3 pilot blacked out
17 engine failure/fire

(22,000 produced)

I shall refrain from calculating percentages to show what an incredibly low percentage of Spitfires were destroyed by structural failure/ engine failure for the reason outlined by Mr Newton. Nevertheless, there is absolutely nothing here to suggest that the Spitfire had some kind of endemic weakness.

BerkshireHunt
03-26-2004, 09:29 AM
[QUOTE]Originally posted by SkyChimp:
He stated that the use of pitot measuring devices were giving false data. _"The reason they saw this false data on the cockpit insturments was very simple. It had to do with the fact that the static system was generally hooked to a pitot tube and had a substantial delay in it reading in a dive, giving false values of the air-speed indicator, altimeter, rate-of-climb indicator, and the lines themselves could not vent fast enough to measure true static pressure in a screaming dive."_
I'm not sure if the speeds achieved by the Spitfire MK XI in that test were recordered by cockpit insturments hooked to a pitot or not, but it seems that -may- be the case.

Hop answered this in the previous thread:

When Isegrim/Kurfurst wrote:
quote:
--------------------------------------------------------------------------------
The method they used to get the airspeed was a simple pitot, which is by no standards is an accurate mean of measuring high mach numbers.
--------------------------------------------------------------------------------
Hop replied:

No, they actually removed the pitot, and replaced it with a new pitot on the wing tip, calibrated up to mach 0.9 by the NPL. They used a 14" trailing pitot comb, linked altimeters, and cameras to record the instruments every second.

To which I can only add- what is a 'trailing' pitot comb and why was it used?
Does it trail the wing ie point backwards?
Is it more accurate at measuring transonic speeds because it's in the wake of the wing and not in the compressed zone forward of the leading edge?

dahdah
03-26-2004, 09:39 AM
Great post BerkshireHunt. Next time I see that infamous list, your post will be posted.http://ubbxforums.ubi.com/infopop/emoticons/icon_smile.gif

p1ngu666
03-26-2004, 09:40 AM
the spitfires wing was very effecient wasnt it?
u cant fit THAT much in it, but u get a sweet aircraft.
its worth mentioning that for the m52 project they used the spit for testing. RAF had jugs and mustangs but used the spit http://ubbxforums.ubi.com/images/smiley/16x16_smiley-happy.gif

http://www.pingu666.modded.me.uk/mysig3.jpg

WOLFMondo
03-26-2004, 09:58 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Arm_slinger:
The Spit wing can reach a speed of Mach 1.3 before it falls apart. The limiting factors was the prop (which sheared off when they tested this), and the tail. I dont know what effects happened on the tail

T4T recruitment officer

Sim lover?, want something new? Then look at "Target for Tonight the definitive night bombing simulation ever, featuring the RAF's Bomber Command.

Got you interested? Look for us here: http://www.nightbomber.com/forums<HR></BLOCKQUOTE>

I thought the spits wing's critical mach number was 0.92?

http://bill.nickdafish.com/sig/mondo.jpg
Wolfgaming.net. Where the Gameplay is teamplay (http://www.wolfgaming.net)

Arm_slinger
03-26-2004, 10:11 AM
Thats what i thought as well. But then some spitfire expert says on national TV that its 1.3 or there abouts and seemed very adament about it

T4T recruitment officer

Sim lover?, want something new? Then look at "Target for Tonight the definitive night bombing simulation ever, featuring the RAF's Bomber Command.

Got you interested? Look for us here: www.nightbomber.com/forums (http://www.nightbomber.com/forums)

Ugly_Kid
03-26-2004, 11:36 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by BerkshireHunt:
[QUOTE]Originally posted by Ugly_Kid:
(The Spitfire) "may not have been also the most rugged design."

I don't want to hijack this thread but I feel the need to put the record straight on this one. The last thread concerning the Spitfire's dive speed was contaminated by Isegrim/Kurfurst's poison pen regarding the Spitfire's structural integrity and I see his contention that it was 'weak' is gaining currency here- which is just what he intended.
<HR></BLOCKQUOTE>

Seems that the conditional form gets lost. I should have also included as rugged as P-something, since people do not seem to be able to follow thought further than three words. http://ubbxforums.ubi.com/infopop/emoticons/icon_rolleyes.gif

I am also quite capable of forming my very own opinion without the aid of Isegrim, thank you very much.

As a side note, Spitfire's critical Mach was certainly not Ma=1.3 (110% sure) and it's more than probable that it wasn't 0.92 either, next guess, anyone? It used to be recommendable to know the meaning of the words before using them.

hop2002
03-26-2004, 11:48 AM
Sorry SkyChimp, I've been too busy the last few days to answer the other thread. I'll give a full reply in this one later, but just this for now:

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR> perused another NACA report on the high-speed characteristics of another WWII era plane that had a lower Cd0 than even the Mustang, and that had wings of the same thickness as the Spitfire - the P-80A.<HR></BLOCKQUOTE>

The P-80A had roughly the same root thickness as the Spitfire, but the tip section was the same as the root, 13.5%, whereas the Spitfire tip section was around 9%.

That means the P-80 and Spit had almost the same root thickness, but the Spitfire wings started getting thinner straight away, the P-80 wings remained the same thickness across their span.

BTW, is the NACA test on the P-80 available on the NACA server? Do you have the report number, if it is?

BerkshireHunt
03-26-2004, 12:02 PM
[QUOTE]Originally posted by Ugly_Kid:
Spitfire was one of the worst diving fighters of that era (acceleration) but it is throughoutly possible that it was controllable to a higher Mach number than many others.

Well, Professor, as you are clearly the man with all the answers I'd like to know the meaning of the word 'throughoutly'?

FW190fan
03-26-2004, 12:38 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Ugly_Kid:
[As a side note, Spitfire's critical Mach was certainly not Ma=1.3 (110% sure) and it's more than probable that it wasn't 0.92 either, next guess, anyone? It used to be recommendable to know the meaning of the words before using them.<HR></BLOCKQUOTE>


According to RAF test pilot Eric Brown, the Spitfire...


"...had the remarkable safe flight Mach number of .83, and I had dived one to Mach .86, although at that speed the aircraft was in a near vertical dive and completely out of control. Of course, the maximum safe flight Mach number is by no means that at which the aircraft can be employed tactically, or, in other words, at which maneuvers can be carried out."

http://people.aero.und.edu/~choma/lrg0645.jpg

p1ngu666
03-26-2004, 12:52 PM
im pretty sure the spits wings could do more than mach 1, given enuff thrust to get there
the spit ingame falls apart too early imo
740true isnt it, roughly?

http://www.pingu666.modded.me.uk/mysig3.jpg
&lt;123_GWood_JG123&gt; NO SPAM!

Nexus2005
03-26-2004, 01:14 PM
Yeh, 740 is about when you're wing falls off http://ubbxforums.ubi.com/infopop/emoticons/icon_frown.gif

http://www.bobcs.co.uk/sig/Nexussig/sig2.jpg (http://www.bobcs.co.uk)

RAF74_Buzzsaw
03-26-2004, 01:27 PM
Salute

The Spitfire could certainly dive to very high speeds without reaching compressibility. Results by test pilots have clearly indicated this. However, that is not to say that the aircraft could maneuver safely at those speeds.

There are many examples of the Spitfire attaining very high speeds in a dive, and then in the pullout, wrinkling its wings an causing serious structural damage, to the point that the aircraft had to be written off.

FORGOTTEN BATTLES does not seem to model G force failure unfortunately. So aircraft do not pull their wings off, or damage them in high speed pullouts, as long as they have not exceeded the aircraft's maximum dive speed.

Hence we have examples like that of the 190's being able to pull 90 degree turns at nearly 900 kph almost instantaneously, and without any damage whatsoever.

The only aircraft which seems to have G Force failure modelled is the P-51, whereas all aircraft should really have this feature. And the P-51's modelling simply has the aircraft explode, rather than varying degrees of damage as in when one exceeds max. dive speed, and begins to lose parts one by one.

BlitzPig_DDT
03-26-2004, 01:44 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by RAF74BuzzsawXO:
FORGOTTEN BATTLES does not seem to model G force failure unfortunately. So aircraft do not pull their wings off, or damage them in high speed pullouts, as long as they have not exceeded the aircraft's maximum dive speed.

The only aircraft which seems to have G Force failure modelled is the P-51, whereas all aircraft should really have this feature. And the P-51's modelling simply has the aircraft explode, rather than varying degrees of damage as in when one exceeds max. dive speed, and begins to lose parts one by one.<HR></BLOCKQUOTE>

The YP-80 (it's not a P-80, something people seem to forget 'round these parts), will snap a wing from G-load. I've done it repeatedly, at a fairly wide speed range too.

Also, the Go-229 and He-162 both explode from G-load. It confuses many people because it happens so quick. The usual exchange goes something like this -
"WTF?"

- "you loaded up too many Gs by pulling too hard"

"but I didn't even black out"

It's not random. I can produce it on command, and stay clear of it so long as I don't make a mistake (or get too long a server freeze - I ride it very close to the edge).


<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Hence we have examples like that of the 190's being able to pull 90 degree turns at nearly 900 kph almost instantaneously, and without any damage whatsoever.<HR></BLOCKQUOTE>

This is an old argument. I haven't checked first hand, but are you sure it's still in AEP? The brief time I spend with the 190 so far makes it seem like it's gone.

==================================
The Blitz Pigs - Not a squad, a Movement!

Come and spam on our front porch.

http://www.blitzpigs.com

faustnik
03-26-2004, 01:49 PM
The 190 has been improved (abilities lessened in high speed roll and elevator control. Oh yeah, and DM! http://ubbxforums.ubi.com/infopop/emoticons/icon_smile.gif


Not sure why Buzzsaw is bringing it up???

He seems right in general though about structural stress damaged not beign modeled. Also, the combination of damage and structural stress limitations would be a great area to investigate for the next sim.

http://pages.sbcglobal.net/mdegnan/_images/FaustSig
www.7Jg77.com (http://www.7jg77.com)
CWoS FB forum. More Cheese, Less Whine. (http://www.acompletewasteofspace.com/forum/viewforum.php?f=25)

BlitzPig_DDT
03-26-2004, 02:07 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by faustnik:
He seems right in general though about structural stress damaged not beign modeled. Also, the combination of damage and structural stress limitations would be a great area to investigate for the next sim.<HR></BLOCKQUOTE>

Agreed. Just that he said that only the P-51 had this accounted for. There might even be more. I didn't even know the P-51 had it. lol

It would be nice if other aspects of G load is incorporated in the next sim. Minor ***itue implications over time, linking "1" plane to a pilot (of a given type) until they leave and rejoin, die, or it gets destroyed. Pilot fatige and G tolerance lessening over the course of the fight, making black out and G-LOC come sooner and last longer. And even add score zero-ing on death. Would make the game more realistic and enjoyable.

==================================
The Blitz Pigs - Not a squad, a Movement!

Come and spam on our front porch.

http://www.blitzpigs.com

RAF74_Buzzsaw
03-26-2004, 02:10 PM
Salute

If the 190 has been made more realistic in its high speed maneuverability, then I appologize. I do not fly it very much at extreme high speeds, but the times I have, I had not noticed any significant changes during high speed maneuvering.

The point I was making, was that all of these planes should be subject to rivets popping out, skin wrinkling, control surface loss, and even structural damage when an aircraft is pulled out from an extremely high speed dive.

If the Spitfire was modelled correctly, it would be capable of diving to very high speeds without damage, AS LONG AS IT DID NOT PERFORM ANY MANEUVERS. However, when the aircraft was recovered from a high speed dive, there would be every chance of damage unless extreme care was taken in the pullout.

Further to the original issue.

The Spitfire was definitely capable of diving to very high speeds, however its acceleration to reach those speeds was not notable.

Almost all the tests done show that most models of the Spitfire (the XIV somewhat excepted) were quite slow to accelerate in a dive when compared to other aircraft of their era.

So the 190 and 109 fans do have a point in that the 190's and 109's should pull away from the Spitfires in a dive in the initial and medium stages of the dive. Only in very long high speed dives should the Spitfires begin to see an advantage.

[This message was edited by RAF74BuzzsawXO on Fri March 26 2004 at 01:25 PM.]

faustnik
03-26-2004, 02:42 PM
I was just reading this at lunch:
"One Hayate of the 1st Air Regiment had to be discarded when its pilot dived out of an ambush by sixteen American Navy Hellcats at 20,000 feet. Coming straight down, and hitting almost 500 m.p.h., the oilot pulled out and got back home. The dural skin was so wrinkled, and so many rivets had popped, the aircraft was completely useless."

- Nakajima Ki-84 a/b Hiyate in JAAF Service, Bueschel

http://pages.sbcglobal.net/mdegnan/_images/FaustSig
www.7Jg77.com (http://www.7jg77.com)
CWoS FB forum. More Cheese, Less Whine. (http://www.acompletewasteofspace.com/forum/viewforum.php?f=25)

Kurfurst__
03-26-2004, 03:47 PM
This may give some idea of the catastropic structure failures during dive recovery.

From Spit V manual. It appears that incorrectly trimming the plane may lead to excessive accelerations during pullout, resuting in airframe failure.

http://www.x-plane.org/users/isegrim/FvsF/spitVdive1.jpg


Also, from the same source, some extra information about controls and handling chartactertics, which completely opposes the in-game experience of yank-bank elevator:


http://www.x-plane.org/users/isegrim/FvsF/spitVstallspin1.jpg
http://www.x-plane.org/users/isegrim/FvsF/spitVstallspin2.jpg

This, along with issues of climb rate at altitude, needs to be fixed properly.

SkyChimp
03-26-2004, 06:39 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>
The P-80A had roughly the same root thickness as the Spitfire, but the tip section was the same as the root, 13.5%, whereas the Spitfire tip section was around 9%.

That means the P-80 and Spit had almost the same root thickness, but the Spitfire wings started getting thinner straight away, the P-80 wings remained the same thickness across their span.
<HR></BLOCKQUOTE>

HA! I didn't even think of that. I've got several good 3 views and technical drawings of the P-80A, and each shows a thinning of the wing from fuselage to tip. But the wing gets narrower from fuselage to the tip also. So the thickness ratio actually stays the same, even though the absolute thickness decreases. I was just assuming thickness ratio decreased, when really it was just absolute thickness.

Regards,
SkyChimp
http://members.cox.net/us.fighters/skychimp.jpg

SkyChimp
03-26-2004, 07:05 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>
BTW, is the NACA test on the P-80 available on the NACA server? Do you have the report number, if it is?
<HR></BLOCKQUOTE>

There are 6 reports on the NACA server dealing specifically with the P-80:

High-speed wind-tunnel tests of a model of the Lockheed YP-80A airplane including correlation with flight tests and tests of dive-recovery flaps
http://naca.larc.nasa.gov/reports/1947/naca-rm-a7a29/

Flight measurements of the flying qualities of a Lockheed P-80A airplane (Army no. 44-85099)- longitudinal-stability and -control characteristics
http://naca.larc.nasa.gov/reports/1947/naca-rm-a7g01/

Flight measurements of the flying qualities of lockheed P-80A airplane (Army No. 44-85099). -lateral- and directional-stability and control characteristics
http://naca.larc.nasa.gov/reports/1947/naca-rm-a7j24/

Wing pressure-distribution measurements up to 0.866 Mach number in flight on a jet-propelled airplane
http://naca.larc.nasa.gov/reports/1947/naca-tn-1181/

High-speed wind-tunnel tests of a model pursuit airplane and correlation with flight-test results
http://naca.larc.nasa.gov/reports/1948/naca-rm-a7i16/

High-speed wind-tunnel tests of a 1/78-scale model of the Lockheed YP-80A airplane
http://naca.larc.nasa.gov/reports/1948/naca-rm-a7l24/


Here is one on the P-51B:

Correlation of the drag characteristics of a typical pursuit airplane obtained from high-speed wind-tunnel and flight tests
http://naca.larc.nasa.gov/reports/1948/naca-report-916/

Regards,
SkyChimp
http://members.cox.net/us.fighters/skychimp.jpg

LEXX_Luthor
03-26-2004, 07:25 PM
Thanks for this one. The FB Spit is easy to stall by following the joystick instructions in the paragraph 2 below.

http://www.x-plane.org/users/isegrim/FvsF/spitVstallspin1.jpg

gkll
03-26-2004, 11:24 PM
Well chimp said something in the previous thread I thought kind of summed it all up, in a way. Something like 'found the magic bullet' - seems to me the response of a man confronted with an unexpectedly worthy opponent... the spitfire wing

Mitchell probably smoked a lot of pipes and pondered that wing. He lived in the midlands right? So in the evening amongst the quiet oaks in the rolling English countryside, he listened to the birds and pulled together all the threads of his training and experience - and dreamed up this wing.... and the bastard got it right! Those Brits have that about their engineering - this intuitive stuff.

Well good for them and good for the spit, so could we have the right dive speed please? 740 is not close - never mind the ailerons Ill keep the cables tight I promise.

gkll
03-26-2004, 11:39 PM
posted Blitzpig -

"It would be nice if other aspects of G load is incorporated in the next sim. Minor ***itue implications over time, linking "1" plane to a pilot (of a given type) until they leave and rejoin, die, or it gets destroyed. Pilot fatige and G tolerance lessening over the course of the fight, making black out and G-LOC come sooner and last longer. And even add score zero-ing on death. Would make the game more realistic and enjoyable."

hear hear!

and I would add an option for pilots not getting further points (ie keep the points rather than lose them so could be overtaken) after 1 or maybe a couple of deaths promote a little realistic risk-taking.

and a switch for a full real FM like I think we've seen glimpses of in earlier versions - so I can play with all the flight manuevers you pilots are all so kind to post for amateurs,, sorry off toopic

[This message was edited by gkll on Fri March 26 2004 at 10:56 PM.]

WWMaxGunz
03-27-2004, 12:30 AM
How many supersonic jets had Spitfire wings?
How many failed attempts at supersonic jets had them?
There were a lot of attempts made in the late 40's era by Britain so I was wondering???


Neal

gkll
03-27-2004, 12:37 AM
Spit Mk VII extended wing HF - Pierre Closterman "The Big Show"

43,000 ft....

"Tally ho, Ian, ready to attack?"
"OK"
He had seen us, but too late. We converged on him. To our surprise it was a Messerschmitt 109G equipped with two fat auxiliary tanks under the wings. He shone like a newly minted penny... First he turned left, but Ian was there, veering towards him. He reversed his turn, saw me, and with a graceful continuous movement, banked more steeply, rolled gently over on his back, diving vertically in the hope of leaving us behind.

Without hesitation we followed hm. He dived straight towards the grey sea which looked congealed, without a wrinkle. He was half a mile ahead of us, with his tanks still fixed to his wings. The speed increased dizzily. At these heights, you have to be careful because you soon reach the speed of sound and then, look out! ...

'... at 27,000 feet my AS indicator showed 440 mph, that is a true speed of 600 mph! I had both hands on the stick and I leant on the controls with all my strength to keep the aircraft in a straight line. The slightest swerve could have crumpled up the wings . I felt my Spitfire jumping all the same, and I could see the paint cracking on the wings, while the engine was beginning to race.

The controls were jammed. We still went on down - 15,000 ft: Ian passed me; 10,000 feet: Ian was 200 yards ahead and 600 from the Hun. He opened fire - just a short burst.

The Me 109G suddenly tore in half like tissue paper, and exploded like a grendade."

The two spits pulled out Closterman using the trim to do so.

Of course it is just some subjective stuff and who knows what really happened? It does suggest the spit dives well enough to match some of the better diving planes... as a minimum

There is a dive speed issue with the spit and I am hoping 1C will get it fixed.

HellToupee
03-27-2004, 12:40 AM
im not aware of anyjets with wings from a spitfire :P

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

pourshot
03-27-2004, 01:44 AM
How about this jet then http://ubbxforums.ubi.com/infopop/emoticons/icon_wink.gif

Supermarine Attacker (http://www.btinternet.com/~a.c.walton/navy/faa/attacker.html)

http://members.optusnet.com.au/~andycarroll68/mybaby.jpeg.JPG
Ride It Like Ya Stole It

WWMaxGunz
03-27-2004, 02:08 AM
Pretty and awesomely fast by WWII standards or even by 1950 standars. Still a long way short of mach 1. I wonder what the high alt dive max was?

EDIT:
Looks like the Attacker wings were Spiteful wings and those were modified Spitfire wings for laminar flow. Very modified! Looking at a scale model built from plans the wings aren't even elliptical! is this true?

www.wbruce.ogilvy.clara.net/text/pics/sc/p27.html (http://www.wbruce.ogilvy.clara.net/text/pics/sc/p27.html)

Also that the Spitfire Swift which did get the speed record and over 1100kph at SL had completely different wings, sweptback and sharp.
END EDIT:

A lot of really good men died trying to pass the barrier. From what I've read the tail configuration was critical and Yeagers bio said the adjustable stabilizer above the wing shock made a critical difference. Some reading I've done said that subsonic design wings just don't cut it above sound. Obviously you need a wing that can handle subsonic speeds to get supersonic but I guess they're writing about best performance and control in one region not being compatible with the best in the other. The rules change. A barn door can be used to make a wing, it's just will not handle anything but dangerously except at certain speeds and attitudes where it will probably go really fast. Enough power and maybe a slightly modified flagpole can be used. Works at all is a longshot from practical at times.


Neal

[This message was edited by WWMaxGunz on Sat March 27 2004 at 01:23 AM.]

[This message was edited by WWMaxGunz on Sat March 27 2004 at 01:27 AM.]

HellToupee
03-27-2004, 03:06 AM
yea the spitfuls wings were square, ive got a pic of a real spitful somewhere

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

pourshot
03-27-2004, 03:14 AM
Yeah it's true the attakers wings are laminar flow but I could not help myself and had to post the link (I'am drunk and needed a giggle http://ubbxforums.ubi.com/infopop/emoticons/icon_smile.gif)

http://ubbxforums.ubi.com/images/smiley/784.gif http://ubbxforums.ubi.com/images/smiley/784.gif http://ubbxforums.ubi.com/images/smiley/784.gif http://ubbxforums.ubi.com/images/smiley/784.gif http://ubbxforums.ubi.com/images/smiley/784.gif

However the test pilot's did say no improvemnt in speed was found in the spitfull by using the laminar wing infact it hurt its handling a fare amount.

http://members.optusnet.com.au/~andycarroll68/mybaby.jpeg.JPG
Ride It Like Ya Stole It

[This message was edited by pourshot on Sat March 27 2004 at 03:29 AM.]

Ugly_Kid
03-27-2004, 03:28 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by BerkshireHunt:
Well, Professor, as you are clearly the man with all the answers I'd like to know the meaning of the word 'throughoutly'?<HR></BLOCKQUOTE>

I do believe "throughoutly" can be found in English dictionary it is related to an adjective "throughout" having a common add "ly" describing a manner of doing something. I do not recall exactly the grammar definition, adverb perhaps. Maybe some helpfull person can fill the gaps. It might be that this is even further away from the original topic but by no lesser means just as interesting http://ubbxforums.ubi.com/images/smiley/blink.gif

SkyChimp
03-27-2004, 06:22 AM
Ok, so the Spitfire has the wings for high speed flight. But I was wondering how it overcomes propeller drag, which is purportedly very high at higher mach numbers. I found this chart on the net comparing propellors - Cds of various NACA 4 digit airfoils at various AoA (the best I could find):

http://members.cox.net/us.fighters/propellerdrag.jpg

Drag coefficients don't appear to get to that "insurrmountable" region of .07 or .08 until very close to mach .9 - as long as AoA is kept low. So it seems possible that the thing that kept the Spitfire from going faster was its propeller.

This seems to lend credence to the claims that the Spitfire did, indeed, break mach .90, and in at least one case lose its propeller during the event.

Does this analysis make sense?

Regards,
SkyChimp
http://members.cox.net/us.fighters/skychimp.jpg

hop2002
03-27-2004, 02:25 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>HA! I didn't even think of that. I've got several good 3 views and technical drawings of the P-80A, and each shows a thinning of the wing from fuselage to tip. But the wing gets narrower from fuselage to the tip also. So the thickness ratio actually stays the same, even though the absolute thickness decreases. I was just assuming thickness ratio decreased, when really it was just absolute thickness.<HR></BLOCKQUOTE>

It suprised me too. So much I went and searched the Naca server for anything on the P-80 to confirm it. It's fairly unusual, at least for ww2 era aircraft.

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>There are 6 reports on the NACA server dealing specifically with the P-80:
<HR></BLOCKQUOTE>

Thanks. I found the ones on latitudinal and longitudinal stability, but I couldn't find the others.

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Drag coefficients don't appear to get to that "insurrmountable" region of .07 or .08 until very close to mach .9 - as long as AoA is kept low. So it seems possible that the thing that kept the Spitfire from going faster was its propeller.

This seems to lend credence to the claims that the Spitfire did, indeed, break mach .90, and in at least one case lose its propeller during the event.

Does this analysis make sense?
<HR></BLOCKQUOTE>

It does to me. Also remember that the prop is relatively small compared to the wing. The Spit's wing had an area of 242 sq/ft, the prop a small fraction of that.

The prop is certainly a limiting factor, though, iirc Martindale suffered two engine failures at high speeds, one of them the constant speed gearbox for the prop litteraly exploded.

pourshot
03-27-2004, 04:09 PM
Many of the dive test I have read resulted in prop and or engine damage so it's logical to conlcude this is what stoped the spitfire from going faster in the dive.

http://members.optusnet.com.au/~andycarroll68/mybaby.jpeg.JPG
Ride It Like Ya Stole It

WWMaxGunz
03-27-2004, 04:21 PM
Maybe it was the lack of control of the Spits in those highspeed dives (at least until they got into a region where the mach speed went up over the dive speed) that made them not try a jet powered Spit to crack the barrier, though I kind of thought they would have with such great wings and frame.
They really tried hard with the prop Spits, that's for sure. Them pilots must have had brass nuts.


Neal

pourshot
03-27-2004, 04:55 PM
This is a very interesting story from one of Alfred Price's book's it's a long post but if I shorten it the context would be lost.

-------------------------------------------

The Spitfire 19 was the final photographic reconnaissance variant of this aircraft, and combined the wing tankage and camera installation of the Mark XI with the Griffon power of the Mark XIV; the combination produced an outstanding reconnaissance aircraft, with the range of the former and the performance of the latter. After the initial 25 production aircraft, the Spitfire 19 was fitted with a pressurised cabin similar to that of the Mark X and the capacity of the wing leading edge tanks was increased to 86 gallons each to give an internal fuel capacity of 256 gallons-three and a half times as much as that of the prototype Spitfire!
The first Spitfire 19s were delivered to No 542 Squadron in May 1944, and by the end of the war it had virtually replaced the Mark XI in the RAF photographic reconnaissance squadrons. The Mark 19 had a maximum speed performance closely akin to that of the Mark XIV, though with a full load of fuel its performance in the climb was somewhat worse; it would appear that the Mark 19 did not undergo a full performance test at Boscombe Down. In service this aircraft demonstrated that it could cruise at 370 mph at 40,000 feet, which was sufficient to place it beyond the effective engagement reach of the German wartime jet fighters.
If the situation demanded it, the Mark 19 could go even higher. In the R.A.F. the term 'service ceiling' was defined as that point where an aircraft's rate of climb fell below 100 feet per minute; the service ceiling of the Spitfire 19 was officially recorded as 42,600 feet. Significantly for this account, it should be noted that this figure was recorded over the British Isles and did not take into account the greater altitudes the aircraft could achieve over the tropics. Moreover that figure gave no indication of the height an aircraft could reach during a lengthy climb ascending at less than 100 feet per minute, for example when en route to photograph a distant target. During the post war air defence exercises over the United Kingdom Spitfire 19s sometimes clawed their way up to 49,000 feet to photograph targets.
In 1952 a Spitfire 19 belonging to No 81 Squadron based in Hong Kong achieved what were almost certainly the highest altitude attained by a Spitfire, and probably the highest speed and the highest Mach number ever achieved by a propellerdriven aircraft. The fact that those last two were accomplished accidentally and despite of the pilot's best efforts, gave added drama to the proceedings.
On 5 February Flight Lieutenant Ted Powles took off in PS 852 from Kai Tak for a meteorological height climb to 50,000 feet, to record the outside air temperature at various altitudes
and report on any clear-air turbulence and high wind speeds that he encountered. The sortie was one of several being flown by the unit, to collect data on high altitude meteorological conditions to assist with the proposed air service through that area by the then-new Comet jet airliner.
At this point it is necessary to digress a little, to discuss the effect of the height of the stratosphere on Powles's sortie. In the band of altitudes below the stratosphere, the air temperature decreases at a steady rate as altitude is increased. Once the stratosphere is reached, however, the outside air temperature remains reasonably constant as altitude is increased over the next 10,000 feet or so. In tropical latitudes (Hong Kong lies just south of the Tropic of Cancer), the stratosphere commences at about 50,000 feet and above that altitude the air temperature remains steady at about -72? C. Moving north or south from the tropics, the altitude of the stratosphere gradually gets lower. Over Great Britain, for example, the height of the stratosphere is around 36,000 feet and above that the air temperature remains steady at about -54?C.
The lower air temperatures at high altitude over the tropics meant that Powles had a substantial performance advantage over a Spitfire 19 making a similar climb over Great Britain. The cold air being sucked into the carburettor of his engine had greater density than a similar mass of warmer air, so his Griffon developed significantly greater power and that enabled his Spitfire to reach higher altitudes.
Powles flew his sortie methodically, levelling at each 5,000 feet step in order to collect and record the required readings, before resuming his climb to the next step. As he neared the final part of the ascent, about 11/2 hours after take off, the Spitfire's rate of climb fell to a few tens of feet per minute. Finally he reached 48,500 feet indicated on his altimeter, which represented a true altitude of 50,000 feet.
At that height the Spitfire's controls were extremely sensitive, but the aircraft still had some performance in hand. Powles recalled:
'I had been up to 48,500 feet indicated, that was 50,000 feet true, at least half a dozen times during earlier sorties. But on that particular day the conditions were perfect, the aeroplane was flying beautifully, I had the time and I had the fuel, so I decided to see if I could get her to 50,000 feet indicated.
Carefully he nudged the aircraft higher until eventually the altimeter read 50,000 feet - a true altitude of 51,550 feet. His airspeed indicator read 108 knots (275 mph true):
217
'I was flying on the very edge of the Spitfire's performance envelope and I felt exhilarated. It felt as if I was trying to balance on top of a ball. I had to fly on instruments, because if I looked over the side a wing would start to drop. I was flying almost on the stall, and if a wing did drop I had to pick it up using opposite rudder; if the starboard wing dropped I eased on left rudder, so that wing moved through the air a little faster and slowly rose.'
Under such circumstances the ailerons could not be used to level the wings, because down-aileron would have stalled the wing on that side and caused the Spitfire to flip on its back and tall out of the sky.
Suddenly Powles noticed that the red cabin pressurisation warning light had illuminated, indicating that cabin pressure had fallen below a safe level. Now he had to get below 43,000 feet as rapidly as possible, before the reduction in pressure caused the nitrogen in his blood to expand and bring on the very painful condition called the 'bends'. Instinctively he pushed the control column forward, at the same time throttling back and moving the pitch lever to 2,200 rpm to prevent the propeller from overspeeding the engine.
'While I was checking to see if the pressurisation seal around the canopy had burst, the aircraft started to shake and when I again looked at my flying instruments, I was shocked to see the needle on the airspeed indicator just passing the 280 kt mark (the Pilot's Notes state that 260 kt should not be exceeded above 40,000 ft!).
I immediately pulled back on the control column, but the more I pulled the steeper the aircraft dived. It was now shaking so violently that I could not read the instruments. The Spitfire was in a vertical dive and I was standing on the rudder bars. The control column was immovable and I was afraid if I pulled any harder something would break. Beside the vibration, the aircraft started to yaw from side to side. I felt as though a giant hand was shaking it.'
The pilot's first thought was to try to ease up the nose using the elevator trim tabs. Glancing out over the wings he noticed that they were covered in a strange mist (caused, we now know, by the shock waves that form at high Mach numbers). Fearing the elevators might be torn off by the airflow if he moved the trim tabs, Powles decided to leave them alone.
Then he remembered an account he had seen of another Spitfire pilot who had got into a high speed dive and was unable to pull out in the normal way. That pilot had recovered the aircraft by pushing the stick forwards instead of pulling it back. Powles resolved to try the same thing and now he pushed on the stick, hard, using both hands.
'Eventually, after the longest few seconds of my life, the vibration and yawing stopped, the mist was clearing from the wings and the nose started to lift. I was still pushing on the unyielding control column and when I felt the resistance lessen the nose dropped again, so I quickly reversed the pressure and started to pull out of the dive. I placed my feet in the top stirrups of the rudder bar and pulled hard on the control column until I started to black out. I then eased the pressure. I could not afford to lose control at this point.' When Powles next scanned his instruments he saw that his airspeed indicator was unwinding rapidly with the needle about to pass through 500 kt, and the altimeter was steady at 3,300 feet. Before that, as the super-cooled aircraft entered the moist warm air lower down, condensation formed on the inside of the windscreen and canopy preventing the pilot seeing anything outside. Now he tried to open the canopy, but it was frozen shut and resisted his efforts to budge it.
As the pilot collected his thoughts he realised he was still in great danger. Since he was unable to see outside the aircraft, he could not establish his position. And in the area were several mountain peaks that extended above 5,000 feet. He initi
ated a climb on instruments and headed south-east towards the sea.
'When I pulled out of the dive and levelled out, the altimeter indicated 3,300 ft. I started a climb with about 1,750 feet per minute showing on the vertical speed indicator, but the altimeter stayed at 3,300 feet for quite some time before it started to rise.'
The chilling conclusion was that during the high speed dive the altimeter had 'lagged', and when the Spitfire bottomed out of its dive it had been somewhat lower than the indicated 3,300 feet. Ted Powles had indeed been lucky to survive with his life.
Then matters began to sort themselves out. A call to Hong Kong Approach Control produced a radio bearing which showed the Spitfire to be safely over the sea. Soon afterwards the canopy unfroze allowing the pilot to slide it back, then the warm air quickly cleared the condensation away from the perspex. Normality returned and Powles found he was flying straight and level at 7,000 feet, over the sea about 15 miles south of Hong Kong island with everything working properly.
After he landed, Powles asked the squadron engineering officer to give the Spitfire a thorough examination to see if the airframe had been overstressed. Surprisingly, PS 852 emerged from the torturous experience without suffering any discernable harm.
After the flight Powles tried to establish exactly what had happened. He had noted the times when he commenced the dive, when he passed 44,000 feet just before the vibration started, and again after the pull-out. Thus he knew that he had taken 9 seconds to descend from 50,000 feet to 44,000 feet, and 47 seconds to descend from 44,000 feet until he levelled out at 3,300 feet on the altimeter (which due to lag in the instrument probably meant a true altitude below 2,000 feet). The descent through about 42,000 feet and the subsequent pull out had taken 47 seconds, which meant that during the dive the Spitfire must have exceeded 1,000 feet per second, or over 680 mph. The aircraft was not fitted with a Mach meter, but Powles had recorded the outside air temperatures at 5,000 foot intervals during his climb so it was a simple matter to work out the speed of sound for each altitude. After collating the available information and applying corrections for compressibility and other factors it seems likely that the Spitfire reached at least Mach 0.94 at 15,000 feet during the dive, equivalent to 690 mph.
Powles had exceeded by a considerable margin the Mach .89 reached by 'Marty' Martindale in the Spitfire XI during the diving trials in 1944. Martindale had commenced his dive at 40,500 feet; Powles inadvertently entered his dive more than 10,000 feet higher, and as he passed 40,500 feet he had already exceeded Mach 0.9 and his Mach number was still rising.
It is not clear whether or not Ted Powles encountered control reversal during his dive, and in retrospect he thinks it unlikely. When the aircraft reached the denser air below 15,000 feet its speed would have started to decay, and thereafter the Spitfire's natural tendency to pull itself out of a dive would have taken effect. If anything, he thinks that his forward pressure on the control column might have delayed the pull out. During the dive Powles had considered using the elevator trim to raise the nose of the aircraft and assist recovery, but it is as well he did not attempt it. Jeffrey Quill has expressed the view that the use of the trim tabs might have caused a high speed stall, and after that the aircraft would have disintegrated.
In the absence of any serious counter-claims it appears likely that on 5 February 1952 Ted Powles achieved the highest altitude ever attained by a Spitfire, 51,550 feet (true). And
219
during his subsequent hair raising dive he reached the highest Mach number, Mach 0.94, and the greatest speed, 690 mph, ever attained by that or any other propeller-driven aircraft. In each case these figures provide resounding endorsements of the soundness of Reginald Mitchell's original design and the improvements made to it during its development.
A total of 225 Mark 19s were built, the last one coming off the production line early in 1946. The variant continued in front-line service in the R.A.F. until April 1954. Fifty examples were exported to Sweden, and a few went to each of the Indian, the Turkish and the Thai air forces.

ps. I would give anything to have a preview post function on this forum.

http://members.optusnet.com.au/~andycarroll68/mybaby.jpeg.JPG
Ride It Like Ya Stole It

Ugly_Kid
03-28-2004, 02:34 AM
Once more the drag coefficient in that Spitfire table is calculated one, based on the thrust which is assumedly also just an estimate. (Unless they measured the thrust from axle, hop?) The values for P-51 and P-80 are windtunnel measurements and thus a direct result (accurate under certain condition). The windtunnel measurements were also done with scale models which results in a problem of matching Reynolds number, speed and Mach number 1 to 1 with real aircraft.

Maple_Tiger
03-28-2004, 04:46 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Ugly_Kid:
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by BerkshireHunt:
Well, Professor, as you are clearly the man with all the answers I'd like to know the meaning of the word 'throughoutly'?<HR></BLOCKQUOTE>

I do believe "throughoutly" can be found in English dictionary it is related to an adjective "throughout" having a common add "ly" describing a manner of doing something. I do not recall exactly the grammar definition, adverb perhaps. Maybe some helpfull person can fill the gaps. It might be that this is even further away from the original topic but by no lesser means just as interesting http://ubbxforums.ubi.com/images/smiley/blink.gif<HR></BLOCKQUOTE>


An adjective changes and modify's nouns or pronouns.

An adverb changes or modify's verbs.

Throughoutly sounds like it is an adverb, in that it helps to describe How something is being done.

Some words can also be adjectives and adverbs.

If i used throughout in a sentence.


*I traveled throughout the country side.*

In this sentence, throughout modifys the verb traveled.

*This kind of rock has been seen throughout western Canada.*

again the adverb throughout modify's the verb seen.


I think adding ly to some words like adjectives will turn them into adverbs.


Jake seems slow today. Jake slowly climed onto the rock.

This is the best i can do in explaining lol. I was trying to think of how i could use the word Throughout as an adjective but it seems that i could only find use for it as an adverb.

Capt. 361stMapleTiger.
http://www.imagestation.com/picture/sraid79/p9158822c9eda67f1dd0b724a5f846229/fb18d0ec.jpg
Proud member of the FBAA and Nutty Philosohpy Club.

Ugly_Kid
03-28-2004, 07:46 AM
Thx, you are probably right. My dictionary lists "throughout" also already as an adverb so adding "ly" might be an overkill. I recall seeing the word with "ly" but I might be confusing it with thoroughly.