Wing breakage: 109 or Spitfire? (1 Viewer)

weaker wing, 109 or Spitfire?


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Having said this, the simplest and most efficient design from structures view is one continuous wing from wing tip to wing tip where there are no discontinuities in the wing spar. Not very elegant for repair or manufacturing considerations, however.

BINGO!
 
Hello Drgondog
as Germans found out during their investigation on 109 dive behaviour, at high altitude high speed dives 109 tended to go into dutch-roll type "oscilation" which should be subdued by using rudder not ailerons.
 
Both aircraft were state of the art when designed and there is no reason to believe that one was weaker than the other. I am sure everyone will agree that if you overstress the airframe then things are going to break. There is some evidence to believe that it was easier to overstress the 109 than the Spitfire.
I say this on the basis of two statements
1) The Luftwaffe did issue in a document issued on the 28th August 1942 an instruction that started 'Owing to the continual recurring accidents caused by wing breakages in Me 109 aircraft' It then proceeded to list new speed limitations at various heights and instruct that these limitations should be placed in all the aircraft.
2) The records for the losses incurred by Jg26 include the following line 'the Geschwader suffered many other losses which should be recognized. 121 pilots were killed in aircraft accidents—wing or engine failure, bad weather, lack of fuel, takeoff and landing mishaps, air collisions, and the catch-all "loss of control".

comment on (1) This is an improvement on the education process. I noticed on the Fw190 documents one of the small differences between the first 190 captured by the British and those that came after it, was a plate reminding the pilot of the speed limitations at various heights which was not on the first 190. It looks as if this became standard practice in the Luftwaffe.
It has been pointed out that the pilots notes on the Spit II give some warnings about what might happen in extreme cases as if this shows a weakness. This I disagree with, the point about Pilots notes is to educate the pilots in what might happen and how to avoid these situations. These are then taught as part of the learning process so the pilot knows how to deal with the situation.
To sum up the Luftwaffe clearly had a problem with wing breakages but the problem seems to have been in the training of the pilot not a weekness in the design itself.

Comment on (2) I have never seen wing failure mentioned in this way for any other aircraft, apart from the Typhoon which of course wasn't a wing problem.
 
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Both aircraft were state of the art when designed and there is no reason to believe that one was weaker than the other. I am sure everyone will agree that if you overstress the airframe then things are going to break. There is some evidence to believe that it was easier to overstress the 109 than the Spitfire.
I say this on the basis of two statements
1) The Luftwaffe did issue in a document issued on the 28th August 1942 an instruction that started 'Owing to the continual recurring accidents caused by wing breakages in Me 109 aircraft' It then proceeded to list new speed limitations at various heights and instruct that these limitations should be placed in all the aircraft.
2) The records for the losses incurred by Jg26 include the following line 'the Geschwader suffered many other losses which should be recognized. 121 pilots were killed in aircraft accidents—wing or engine failure, bad weather, lack of fuel, takeoff and landing mishaps, air collisions, and the catch-all "loss of control".

comment on (1) This is an improvement on the education process. I noticed on the Fw190 documents one of the small differences between the first 190 captured by the British and those that came after it, was a plate reminding the pilot of the speed limitations at various heights which was not on the first 190. It looks as if this became standard practice in the Luftwaffe.
It has been pointed out that the pilots notes on the Spit II give some warnings about what might happen in extreme cases as if this shows a weakness. This I disagree with, the point about Pilots notes is to educate the pilots in what might happen and how to avoid these situations. These are then taught as part of the learning process so the pilot knows how to deal with the situation.
To sum up the Luftwaffe clearly had a problem with wing breakages but the problem seems to have been in the training of the pilot not a weekness in the design itself.

Comment on (2) I have never seen wing failure mentioned in this way for any other aircraft, apart from the Typhoon which of course wasn't a wing problem.

Glider - I know of several specific 'wing' failures on the P-51B that were traced directly to an unexpected drop of main gear in a dive... all in the March-April 1944 timeframe. This was solved in retrofit gear and gear door uplock kits and permanently with the P-51D.

It was unclear whether the gear sagged on high G pullout or the wheel door opened due to aerodynamicloads. The Mustang ammo doors were also stiffened when RAF dive tests (at ~.82-85M) noted the 'bulging ammo door' under the shockwave.
 
I don't disagree with you, my posting was specific to the 109 and Spitfire. The P51B issue you mention are similar to the aileron instability instances in the Spitfire which caused structural failure in 22 Spitfires. The failure was a problem caused by an unforseen situation, which was identified and fixed. In wasn't a weakness in the wing or any other part of the design as the failure was a symptom of the problem not the cause.
The most common cause for a structural failure is the pilot overstressing the airfame which happened in about 46 cases iro the Spitfire. This could happen in any airforce as as far as I know accelerometers were not fitted to any WW2 aircraft. This would have almost eliminateded the problem.
 
Hello
I don't recall any wing failures on FAF's 109Gs during the war. One G-2 was lost when its pilot tried to disengage by a deep dive, plane probably went over max allowed speed and lost its elevators during pull-out, plane crashed, pilot KIA. And of course some 109s were lost to unknown causes. Clearly more losses happened because of engine failures. But from march 44 onwards Finns always checked the fastment of tailplane of new 109G-6s they got from Germany.

But FAF had rather few 109s, From Spring 43 to Spring 44 one laivue/sqn/gruppe, TOE 30 planes but usually badly understrength, on 1.1.44 it had only 13 109s serviceable + 3 in maintenance, from Spring 44 onwards two laivuetta/sqns/gruppen later a couple more sqns also got at least some, during heavy battles of Summer 44 say 30-60 Bf 109Gs serviceable daily.

Early 109G-6s designed load was 6,2G /3100kg(normal) and 5,6G / 3300kg (for ex. /R6 with two MG 151/20 gunpods). For later reinforced G-6s, or earlier when reinforced, figures were 7,0G / 3100kg and 6,5G / 3300kg.

Juha

Thank you Juha.

Your numbers are correspunding to the soviet ones (6.3 G) for the 109E-3 at 2500 kg.

The security factor Q was certainly 12 for the 109, but it was 13 for french Standards and even 14-15 for soviet ones. Nothing exceptionnal.
In order to calculate applied load Q to CG distribution, you have to divide it by l (lenght) momentum for all airframe parts. Sorry for my english.

It makes 7.5 G for early D-520, 6.5G for the I-26, even 8 G and more for LaGG-1 and MiG-1 calculated to use more powerfull and heavy engines.

So unlike what Soren thaught, the 109 could not withstand 12 * 3100 kg load on its wings. Moreover there is no use for that, pilot is loosing conscience if exposed at 5-5.5 G and dying after prolongated exposure to 6G. For all pilots in all countries with no high-G clothes.

The main problem for Spit and Me-109 wings was their monospar wing structure. Thus being very light cause spar being positionned at the max thikness of the wing, were suffering on torsion efforts, unlike 2 spars or multispar wings.

The thin Spitfire wing was probably less suffering at high speed from compression efforts due to dynamic pressure.
Both were weak on a dive recovery when aerodynamical focus were suddenly moving on.


Regards
 
VG-33 said:
The security factor Q was certainly 12 for the 109, but it was 13 for french Standards and even 14-15 for soviet ones

14 to 15 G for Soviet designs??? Rubbish. I'd like to see even a single shred of evidence to support that.
 
14 to 15 G for Soviet designs??? Rubbish. I'd like to see even a single shred of evidence to support that.

It was exactly Q= 13 minima allowed usually added with 15-25% for further developpement majoration from soviet 1937 Standards. Look after Ostolsawki books or/and RDK manuals. Or better wright to Kosminkov.

Or in I-153 technical manual in the Web.

Anyway, try to understand why you're posting before doing it.

Regards
 
You are welcome, VG
And thanks a lot for the info on Soviet and French standards.

Hello Glider
Thanks for the info on German problems and their solution to it. The Finns as far as I remember didn't notice problems with 109G's wings but surely with DB 605A, especially early on, and with very heavy control forces at high speed.

Juha
 
I don't believe the Q factor was any different for USSR, UK, German or US a/c.
 
You are welcome, VG

Hello Glider
Thanks for the info on German problems and their solution to it. The Finns as far as I remember didn't notice problems with 109G's wings but surely with DB 605A, especially early on, and with very heavy control forces at high speed.

Juha

This was common across the 109 versions with the possible exception of the 109K. The 109E certainly had similar problems and the loss of height incurred when pullng up from a fast dive was if I remember correctly up to 3,000 ft.
 
excellent information VG

Thank you

Some other precisions.

From old french sources, Mach-1 , encyclopédie de l'aviation, it was commonplace for the early 109F to loose wings or tailplanes, with no more precisions.

I excpect that if prof Willy did no forget to reduce wing size from Emil to Fredrich, he forgot to reinforce it enough. Moreover we can see from 109E3 wing structure that main spar was positionned aft from the max profile thikness and was working in bad overhang conditions.

bf109e3_20.jpg


For the reduced chord 109F wing it was even worse, since due to the unchanged wheel size it was positionned even after in the profile. We can also see that 109's wing had a lot of remouvable panels reducing it's rigidity.


On the same time from TsAGI spécialists

???????? Mk.IX. ??????? ?????? ?? ???????????? ????????

we can learn that

spitfire wing was in one piece better for materials resistance items, but complicating maintenance and mass producing.

6) Its typical monospar wing. Stress efforts to breakage line are abosbed by the main spar. Aft spar is only working on torsion ones.

7) Strong leading edge skin alogether with the main spar is working as D shaped torsionnal half box.


8) The close positionned at 26.8% of the mean chord spar allows to use at best max profile hight, and to keep the whell inside the relatively small thikness wing.

9) Ellptic wing....is better for induced drag...difficult to build.

10) Superiority of the telescopic square made spare booms. No such...on other planes due to production difficulties.

11) The weight of spitfire wing structure is much lighter (20 kg/m²) than other contemporary fighter planes (25 to 30 kg/m²...even more for soviet wood ones). But relativly thin skin 0.6 mm that probably easy to deformate after some prolongated efforts.

Etc...

I think it's not bad to have an educated and valuable but neutral point of view betwenn the both planes.
And it seems that Spit's wing was better concieved for torsionnal efforts on the ending point.

No reason for BNT (new technologies bureau) TsAGI to make some propaganda for foreigh designs. Or just for one of them...


regards
 
Look after Ostolsawki books or/and RDK manuals. Or better wright to Kosminkov.
Regards

Hi VG-33,
I did not find anything with Google search of "Ostolsawki" or "RDK" or "Kosminkov".
Can you give direct Amazon book links (ISBN number) or internet links.
 
I excpect that if prof Willy did no forget to reduce wing size from Emil to Fredrich, he forgot to reinforce it enough. Moreover we can see from 109E3 wing structure that main spar was positionned aft from the max profile thikness and was working in bad overhang conditions.

Hmm, before you start to speculate and start to share somewhat unusual theories on the Bf 109 wing structure, and how it evolved between variants, you should perhaps study the basics of the subject, as currently you don't seem to grasp even the basics, nor do you have any solid sources on which to base your very definitive claims.

Basically:

a, You don't seem to understand how the load bearing worked on the Bf 109 wing. It was single main spar with the thickened ribs and thickened skin forming a box spar. The strenght properties were tested by both the British and the Americans and were actually found to be quite good, on par with US two spar designs. Ooops...

b, Moreover the Bf 109F did not have reduced wing area, unless you are talking about the prototype. On the serial production F only the planform changed, and only very slightly to allow for the elliptic wingtips, otherwise as far as structure goes, it was practically the same size and identical.

For the reduced chord 109F wing it was even worse, since due to the unchanged wheel size it was positionned even after in the profile.

c, The Bf 109F did not have reduced chord... :rolleyes:

We can also see that 109's wing had a lot of remouvable panels reducing it's rigidity.

This is silly for two reasons... first of all it appears you didn't see much of a 109 wing in real life.. I can only recall two such panels, one on each wing, outside the wheel wells which are fastened with screws rather than rivets. These serve as bays for the gondies and/or wing bottles.

Secondly there are such removable wing panels on practically all aircraft, certainly on those with wing guns... how do you think the armourers reload those guns, they push cannon rounds through the skin, or tear it up and flush rivet it after every sortie...? :rolleyes:

spitfire wing was in one piece better for materials resistance items, but complicating maintenance and mass producing.

6) Its typical monospar wing. Stress efforts to breakage line are abosbed by the main spar. Aft spar is only working on torsion ones.

7) Strong leading edge skin alogether with the main spar is working as D shaped torsionnal half box.

8) The close positionned at 26.8% of the mean chord spar allows to use at best max profile hight, and to keep the whell inside the relatively small thikness wing.

9) Ellptic wing....is better for induced drag...difficult to build.

10) Superiority of the telescopic square made spare booms. No such...on other planes due to production difficulties.

11) The weight of spitfire wing structure is much lighter (20 kg/m²) than other contemporary fighter planes (25 to 30 kg/m²...even more for soviet wood ones). But relativly thin skin 0.6 mm that probably easy to deformate after some prolongated efforts.

Every design had certain advantages, but basically you are talking about a wing that retained an ultimately defunct element in the original design (evaporate cooling), ie. the front D torsion box, or a mere byproduct of other considerations (ie. elliptical wing which was only adopted to make place for extra wing guns).

Basically the only unique thins about it is the spar design (which none seem to have bother to copy, and regardless of the claims of its strenght, only marginal external wing stores were allowed on the Spitfire, which is a hint on its capabilities) whole load bearing is concentrated in the front of the wing as a result, and there's nothing to take the load in the rear areas.Nobody copied that latter aspect either, as it was not particularly difficult to realize that such assymetric layout is going to resist twisting forces badly, regardless how it resists the normal pitch-induced loads. As noted, it was only a remnant of a given up, defunct element of the very first drawings.

I think it's not bad to have an educated and valuable but neutral point of view betwenn the both planes. And it seems that Spit's wing was better concieved for torsionnal efforts on the ending point.

Basicallly you would need something solid to back that up... torsional tests, for example. Some test results for both wings are availalbe, and its rather clear that the (original until Mk 21) Spitfire wing had serious problems in dealing with twisting loads. The Spit had by far lower aileron reversal speed than any other aircraft (somewhere between 520 and 580 mph), and that being some 250-300 mph lower than that of the Bf 109F or the P-47 as a matter of fact.

The odd thing is you see, that the first thing they decided to throw away in the Spitfire was its wings, when they redesigned the thing with the Mark 20 series 8) - not counting those aircraft which did this unintentionally, of course. :twisted:
 
Looking at the 109's wing structure it looks just as strong as the Spitfires, and higher thickness ratio would've helped keep the wing more stiff than the Spitfire's.
 
Both aircraft were state of the art when designed and there is no reason to believe that one was weaker than the other. I am sure everyone will agree that if you overstress the airframe then things are going to break.

Basically true. I don't think there was any great difference between the stress limits of the two airframes, nor that it is to be blamed on the airframe if the pilot does not adhere the operational limits of the airframe.

There is some evidence to believe that it was easier to overstress the 109 than the Spitfire.

I say this on the basis of two statements

1) The Luftwaffe did issue in a document issued on the 28th August 1942 an instruction that started 'Owing to the continual recurring accidents caused by wing breakages in Me 109 aircraft' It then proceeded to list new speed limitations at various heights and instruct that these limitations should be placed in all the aircraft.

Hmm, that paper is worded a bit differently, as it goes as noting that " in Me 109 aircraft, attention is brought to the following:

The maximum permissable air-speeds in the different heights are not being observed and are widely exceeded."


Its a bit different than how you put it - the 28th August 1942 does place limitations on diving speed, but the context is that the pilots routinely ignored and widely exceeded the existing dive limit speeds...

Secondly its a bit bizarre to argue that the German paper issued at the end of August 1942 is some sort of evidence that the Spitfire was less likely to be overstressed in dive, as you were already shown (several times) the British papers preceeding the German papers by a couple of months, and dealing with the very subject of

"several accidents to Spitfire V aircraft in service... attributed to excessive accelerations in pullouts from dives with consequent failure of the wing structure"

Firstly it is blatantly evident from the British paper that Spitfire wing structure failures occured and were a serious concern to the RAF the same time the LW became concerned about the same in the 109 (and I guess it is true for a couple of other airforces, which just become aware of the dangers at high Mach speed).

spits2.jpg


Secondly there's a difference - whereas the structural failures of the 109s were attributed to the pilots disobedience of the dive limits of their aircraft, the Spitfire wing failure accidents were attributed to a design aspect of the Spitfire, namely that the aircraft had a tendency to tighten up the turns in high speed dives, and overload itself... that was a fault of the design, not the pilot who flew it.

It has been pointed out that the pilots notes on the Spit II give some warnings about what might happen in extreme cases as if this shows a weakness. This I disagree with, the point about Pilots notes is to educate the pilots in what might happen and how to avoid these situations. These are then taught as part of the learning process so the pilot knows how to deal with the situation.

The Spitfire II Pilot's notes is very definietive about certain dangers stemming from the control characteristic of the aircraft (poor pitch stability, and overly sensitive elevator control). While indeed there are some generic limitations laid down in the manual which are valid for all aircraft, some are very specific to the Spitfire regardless how you blurr it.

SPIT24.jpg


The manual uses no uncertain terms that the aircraft has very sensitive controls, and it is easy to overload the design, and also notes that this could be easily done accidently, ie. due to unintenional movements of the pilot's hand in bumpy weather. Furthermore it makes clear warning not to trim the aircraft for level flight during dives because doing so exaggrevates the pilot's capacity to overload the airframe. Dives and bumpy weather are hardly ''extreme cases''...

The issue is simple to understand - the Spitfire had unusually low stick force stability, at about 4 lbs required to pull 1 G; the 109 was on the high side, at around 20 lbs/G.

Say a 109 and a Spitfire is a dogfight, both pilots pulling as much as possible on the stick, near their human limits, pulling 5 Gs... suddenly a blow of wind, a propeller from an aircraft or an AA shell exploding nearby shakes both aircraft and pilots, who accidentally pull another 20 lbs on the stick... the Spitfire is now pulling 10Gs all the sudden instead of 5, the 109 is now pulling 6Gs instead of 5...


2) The records for the losses incurred by Jg26 include the following line 'the Geschwader suffered many other losses which should be recognized. 121 pilots were killed in aircraft accidents—wing or engine failure, bad weather, lack of fuel, takeoff and landing mishaps, air collisions, and the catch-all "loss of control".

And the point...? Accidents happen in war, people die, or that amongst the number of fatalities related to accidents, some were related to wing failures - and we do not even know how many, probably a fraction of takeoff/landing/enginefailure-related accidents, which were always the main causes...

Comment on (2) I have never seen wing failure mentioned in this way for any other aircraft, apart from the Typhoon which of course wasn't a wing problem.

You never seen Spitfire, Yakovlev, Mustang, Thunderbolt, Focke-Wulf 190 etc. pilots mentioned to be killed due to wing or engine failures, bad weather, lack of fuel, takeoff and landing mishaps, air collisions, and the catch-all "loss of control"...? I very much doubt that...

Or you say you didn't see wing failure mention in context of other aircraft - say for example wing failures mentioned for Spitfire in documents you saw about a day before you wrote this? Or what way?
 
Hello Kurfürst
Quote:" The Spit had by far lower aileron reversal speed than any other aircraft (somewhere between 520 and 580 mph), and that being some 250-300 mph lower than that of the Bf 109F or the P-47 as a matter of fact."

Copy from an old thread from hitechcreations.com/forums, do you recall?

"gripen 10-04-2005 10:39 AM

Originally posted by Kurfürst
The aileron reversal speed for the Me109 can be derived in FB 1951 and is around 611 mph while the Spitfire had only 510 mph (source avia report 6/10126 from the RAE).


Actually FB 1951 gives the reversal speed in TAS and RAE data gives it IAS (or EAS). Feel free to convert values comparable. The RAE 1231 (DSIR 23/12865) gives reversal speed 580 mph EAS for the Spitfire V with standard wings and that value is calculated from flight test results.

Knegel 10-04-2005 03:59 PM

TAS IAS conversion at 3000m = 0,849"

To others IIRC the German test was flown at 3000m
 
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Basically true. I don't think there was any great difference between the stress limits of the two airframes, nor that it is to be blamed on the airframe if the pilot does not adhere the operational limits of the airframe.



Hmm, that paper is worded a bit differently, as it goes as noting that " in Me 109 aircraft, attention is brought to the following:

The maximum permissable air-speeds in the different heights are not being observed and are widely exceeded."

Its a bit different than how you put it - the 28th August 1942 does place limitations on diving speed, but the context is that the pilots routinely ignored and widely exceeded the existing dive limit speeds...
My understanding is that the paper says what I said it said


Secondly its a bit bizarre to argue that the German paper issued at the end of August 1942 is some sort of evidence that the Spitfire was less likely to be overstressed in dive,
You clearly didn't read what I wrote. I was quoting the paper to prove that the Luftwaffe did have a problem with wing failures, that the problem wasn't that the wing was weak but the airframe was being overstressed and the paper outlined the corrective action taken. This I supported with the additional plate fitted to Fw190's to emphasise that this seems to have become standard practice in the Luftwaffe. There is nothing wrong with that.

as you were already shown (several times) the British papers preceeding the German papers by a couple of months, and dealing with the very subject of

"several accidents to Spitfire V aircraft in service... attributed to excessive accelerations in pullouts from dives with consequent failure of the wing structure"

Firstly it is blatantly evident from the British paper that Spitfire wing structure failures occured and were a serious concern to the RAF the same time the LW became concerned about the same in the 109 (and I guess it is true for a couple of other airforces, which just become aware of the dangers at high Mach speed).
I certainly agreed that some Spitfires had been lost due to overstressing the airframe and mentioned it in my posting. Did you not read that?


Secondly there's a difference - whereas the structural failures of the 109s were attributed to the pilots disobedience of the dive limits of their aircraft, the Spitfire wing failure accidents were attributed to a design aspect of the Spitfire, namely that the aircraft had a tendency to tighten up the turns in high speed dives, and overload itself... that was a fault of the design, not the pilot who flew it.
Unfortunately you have chosen to present part of the paper that says what they are looking into not the piece that deals with the investigation. If this is the paper that I read in the entirety, the problem was associated to the change in the COG as new equipment was added to the Mk V which was easily fixed once the problem had been identified.


The Spitfire II Pilot's notes is very definietive about certain dangers stemming from the control characteristic of the aircraft (poor pitch stability, and overly sensitive elevator control). While indeed there are some generic limitations laid down in the manual which are valid for all aircraft, some are very specific to the Spitfire regardless how you blurr it.

SPIT24.jpg


The manual uses no uncertain terms that the aircraft has very sensitive controls, and it is easy to overload the design, and also notes that this could be easily done accidently, ie. due to unintenional movements of the pilot's hand in bumpy weather. Furthermore it makes clear warning not to trim the aircraft for level flight during dives because doing so exaggrevates the pilot's capacity to overload the airframe. Dives and bumpy weather are hardly ''extreme cases''...
Pilots notes are by definition to educate the pilot of the limitations of the aircraft. The pilots are then trained to avoid the problem and/or deal with the problem. I and no doubt other pilots on the forum will have had this experience, in my case the Pilots Notes said that intentional spinning was forbidden but I was intentionally put into a spin so I could learn how to recover.
I would rather be made aware of a problem, how to recognise the danger and not crash, than not be told and have an accident.

At the end of the day what matters is the frequency with which these accidents happened.
We know from Mr Eric Newton who spent the war with the Air Accident Investigation Branch that there were 121 Spitfire crash investigations between 1941 and May 1945 involving serious structural failure and the breakdown for the Spitfire is approx
:
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

From the list that you produced showing the failures in the Spitfire it is clear that a high proportion of the above accidents (probably over 50%) happened in training units with inexperienced pilots. On that basis most RAF front line squadrons didn't have a single structural failure the entire war.
The issue is simple to understand - the Spitfire had unusually low stick force stability, at about 4 lbs required to pull 1 G; the 109 was on the high side, at around 20 lbs/G.

Say a 109 and a Spitfire is a dogfight, both pilots pulling as much as possible on the stick, near their human limits, pulling 5 Gs... suddenly a blow of wind, a propeller from an aircraft or an AA shell exploding nearby shakes both aircraft and pilots, who accidentally pull another 20 lbs on the stick... the Spitfire is now pulling 10Gs all the sudden instead of 5, the 109 is now pulling 6Gs instead of 5...
This is priceless, suggest you stick to facts

You never seen Spitfire, Yakovlev, Mustang, Thunderbolt, Focke-Wulf 190 etc. pilots mentioned to be killed due to wing or engine failures, bad weather, lack of fuel, takeoff and landing mishaps, air collisions, and the catch-all "loss of control"...? I very much doubt that...
I have never seen an RAF unit list wing failure as a type of loss. As a one off exceptional event yes, but not in the same manner that Jg26 did.
 
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Hello Kurfürst
Quote:" The Spit had by far lower aileron reversal speed than any other aircraft (somewhere between 520 and 580 mph), and that being some 250-300 mph lower than that of the Bf 109F or the P-47 as a matter of fact."

Copy from an old thread from hitechcreations.com/forums, do you recall?

"gripen 10-04-2005 10:39 AM

Originally posted by Kurfürst
The aileron reversal speed for the Me109 can be derived in FB 1951 and is around 611 mph while the Spitfire had only 510 mph (source avia report 6/10126 from the RAE).


Actually FB 1951 gives the reversal speed in TAS and RAE data gives it IAS (or EAS). Feel free to convert values comparable. The RAE 1231 (DSIR 23/12865) gives reversal speed 580 mph EAS for the Spitfire V with standard wings and that value is calculated from flight test results.

Knegel 10-04-2005 03:59 PM

TAS IAS conversion at 3000m = 0,849"

To others IIRC the German test was flown at 3000m


Its not entirely clear who says what in this five year old post - you appear to be quoting gripen - but it seems to be a similiar discussion on the subject.

Anyway, a few things needs to be clarified.

a, First of all the information in that post can be regarded as obsolate. There is solid information that contradicts it.

b, I suppose FB 1951 refers to the German DVL report regarding with elastics measurments on the 109F. The said report does not give computed aileron reversal speeds, even less gives them in TAS.... The statement of Juha "Actually FB 1951 gives the reversal speed in TAS" can be considered baseless unless he can actually quote the report where it says that (I have the report, and I do not recall ever seeing such information. It seems that gripen claims that, and it would be an understatement to say that gripen's credibility has a rather jagged record, as you must be aware of that from numerous threads on that board.

c, furthermore the context (" can be derived in FB 1951 and is around 611 mph ") suggest - in fact, makes rather clear - the value was estimated by the poster. The DVL report has a roll rate chart, and I suppose the poster made a simplistic estimatation by extending the roll curve and looking where it matches the X axis (ie. flight speed). I believe the assumption was where roll rate would be = 0, if we extend the roll curve, that would reversal speed.

The final word, aileron reversa speeds for the Bf 109F, based on experiments carried out on Bf 109E and F wings was found to be 850 mph by Material Command in 1944 and is noted to be similiar in this respect to the qualities of an unspecified AAF fighters at the time (I wonder which fighter they referred to?).

Now that the factual has been established, I leave it to you to explain the extent of difference between the 850 mph aileron reversal speed specified by MatCom for the Bf 109F* and the 510 mph (as given by avia 6/10126) or the 580 mph EAS (given by DSIR 23/12865, take your pick).

I feel that an extraordinate amount of explanation shall be required, and it will be very thin on documentation.

* Note that the wing structural strenght was beefed up on the Bf 109G, so the reversal speeds are probably higher on the G series than was on the F series.
 

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