Me109 F Intelligence

[Glider]

I was able to spend an afternoon at the National Archives and tried to look into what they have on the Me109F. The result was I didn't have nearly enought time as they have about a dozen files and you can only look at three at a time.
I concentrated on the Performace folder which contained the details of the air test of the 109F and the results of the Interigation of two captured pilots one very experienced and the other one on his first mission over the UK. These I found most illluminating more so than the air tests themselves.

Most people are aware that the airtests themselves were seriously hampered by the engine problems that were encountered. These happened at altitude and invovled the loss of oil pressure. The RAF were very keen to see what the 109F was capable of and the tests were the best done in the time available however the aircraft crashed killing the test pilot only days after they started. What I noticed was that there was also a file on the air test of an Me109E and a Me110 both of which had DB601N engines and all three aircraft had serious problems with failing oil pressure. There was a note that Rolls Royce had been given one of the engines to try and identify the problem as they had a high altitude test chamber which could simulate the environment. There was a also a comment in the Me109F file that the engine was old, unfortunately it didn't go into detail. In case anyone asks they didn't say what version of the 109E or 110 was in the test, just that they had the DB601N engine.
I have to wonder that if all the DB601N engines the RAF had suffered from the same problem was there a generic issue with the early DB601N engines? If anyone can can assist with this I would appreciate it.

Moving on to the interigation. The first one is with the experienced pilot who had served in Spain. I noticed a number of points.
1) His Me109F had been equiped with a 20mm at his request, which implies that some 109F2 aircraft had the 20mm cannon not the 15mm cannon
2) Wing failure was a serious concern. He mentions that in three weeks at least two pilots had been killed when the wings failed including one named experienced pilot.
3) The cockpit is cramped for pilots who are heavily built
4) The German pilots believe it to be more manoeuverable than the Spit in every way apart from in a turn when a well handled Spit might still turn inside the 109
5) The German pilots had no problem with the reduced armament (but he himself had increased his to a 20mm) so a question must exist on this statement.
6) The Sterling is considered to be a tough opponent well able to defend itself.
7) The comments on tactics are very interesting and the Germans admire the RAF direction system.
8) The detail of the information that the RAF were able to obtain was to me unexpected. He is an experienced fairly senior officer who wouldn't have just talked. It shows what experienced, trained people can obtain from captives and I have no doubt that other nations were as adept as the RAF. Here I should note that this questioning was treated with care and in some detail. The RAF had yet to capture a 109F and it was causing serious concern. Special questions were prepared before the interview and a lot of planning took place.

The original documents were very poor and I have done what I can to tidy them up. If anyone would like clarification of any part please let me know. I will do the second interview tomorrow.

 

[Glider]

These were the questions to be put forward during the interview

 

[Micdrow]

Very cool info there Glider, many thanks in advance. As far as reading goes take a look at this. I made them into a pdf file. After a few days I will move this to the technial section so it does not get lost as easy. Many thanks again!!!!

Paul

 

[Juha]

Seems very interesting, Thanks a lot, Glider!

And thanks to Micdrow, too!

Thankfully
Juha

 

[Airframes]

Excellent work Glider! A catalogue of this type of information, in 'narrative' book form, would make a very interesting read, and also a great 'one stop' reference source for a number of applications - authors, artists and modellers being some.

 

[stona]

Excellent stuff. I believe the officer being interrogated here is Rolf Pringel who was shot down near Dover on this date.As I Gruppe Kommandeur he would have been quite a catch for the RAF intelligence officers.
His comments about the Stirling may be coloured by the cause of his demise which is given as Stirling/Spitfire in some JG26 casualty lists.
Question 8 grabbed my attention. The "varied and weird camouflage schemes" even at the time warranted a specific question. Pringel's answer was not particularly helpful,some units were certainly flying with non standard schemes at this time.
Steve

 

[Glider]

Stona
You are almost certainly correct when you say that its likely to be Pringle who was being questioned. The records avoid any mention of exact names but there cannot be many pilots of his rank captured in a 109F. Re the comment on the Sterling again you could be correct but its fair to remember that the Sterling was an agile bomber capable of taking a fair amount of damage. if you are in a standard 109F2 with only 1 x 15mm and 2 x LMG a Sterling may well take some shooting down.

All
The second interigation turned out to be a pilot from a 109E not F, what it was doing in the 109F folder I don't know so I have copied the other documents that I have on the 109F and will do the second interigation tomorrow.

The first paper is an immediate suggestion as to a change in tactics when undertaking a sweep re the use of bombers. It can not have come about as a result of the information given by Pringle as the dates don't match but a previous pilot must have given similar information.

The second is a letter from Douglas Bader urging that feedback to the operational squadrons is speeded up compared to previous experience with the testing of a 109E. It should be noted that when the Fw190 was captured all these suggestions and others were taken on board and implemented with small changes.

The last two are the Issues Logs for the109F showing what the problems were with the aircraft. From what I can see the level speed tests undertaken at lower altitude were accurate and no comments were made about engine problems or unexpected results. It was only at altitude where things went wrong resulting in the fatal accident.

Again the papers were pretty poor and if anyone would like clarification please don't hesitate to let me know.

 

[stona]

More great stuff! I notice Bader's letter confirms that this was indeed Hauptmann Pringel's aircraft,even though he has mis-spelt the name slightly.I'm not sure he should have named him at all.
Thanks for posting this material.
I like Bader's last,rather cheeky,suggestion that (effectively) he should be given a chance of flying the aircraft
Steve

 

[Milosh]

Great stuff Glider.

Of interest is the comment on wing failures. Never heard of this before, though the early Fs had rear fuselage failures.

 

[timshatz]

Glider, I'm assuming it was the national archives in England?

 

[Maximowitz]

Yes, the NA at Kew in London. Used to be called the Public Records Office.

Tons and tons of stuff there but badly indexed and referenced. You could spend weeks there looking for information and find nothing.

 

[Glider]

More great stuff! I notice Bader's letter confirms that this was indeed Hauptmann Pringel's aircraft,even though he has mis-spelt the name slightly.I'm not sure he should have named him at all.
Thanks for posting this material.
I like Bader's last,rather cheeky,suggestion that (effectively) he should be given a chance of flying the aircraft
Steve

This idea was taken up when the FW 190 was captured. The initial tersts were undertaken by the RAE but before it was taken apart it was made available to one pilot from each Group. They flew against it in their own aircraft and in it against one of the other operational pilots. Each Group could and did send other pilots to observe and the numbers were such that the visitors had to land at another base and transport was laid on to the airfield in question.

I should add that these papers came from the AIR 16/350 file at the National Archives at Kew.

 

[stona]

Great stuff Glider.

Of interest is the comment on wing failures. Never heard of this before, though the early Fs had rear fuselage failures.

I remember a post war interview with Bader (a shameless self publicist) in which he said that German pilots were reluctant to pull out of a dive too quickly when going very fast. "A bit porky on the joy stick" was his actual comment. His request in the letter regarding the Bf109F's performance "when pulling out of a steep dive of say 440mph" would indicate that he already had his suspicions about this in 1941. Pringel himself appears to indicate that at least two pilots had recently been killed ripping the wings off their aircraft.
I still find it amazing that a man of Pringel's calibre and seniority would give such detailed answers to his interrogators,maybe he was still as confident as he sounded of the final victory. He didn't have to answer,noone was going to pull out his fingernails!
Steve

 

[Vincenzo]

the question it's also the reply are honest or just tried to give false/partly false information...

 

[Soren]

British interrogator: *So "Hans", this new tank your army is deploying, you called it "Tiger" I believe?*
Hans: *Jah, zhat is correct*
British interrogator: *You say it is very thinly armoured and doesn't really pack much of gun?*
Hans: *Jah jah, zhat is correct, very kleine pea zhooter und almozt kein panzer*

 

[Soren]

As for the strength of the Bf-109's wing, it was atleast as strong as that of the Spitfire. So unless the Spitfire lost its wings a lot then Bf-109 didn't either. This fear of a catastrophic wing failure stemmed from experiences with the older Bf-108, and it was a well known problem. The Bf-109 featured a much stronger assembly however, and the wing was reportedly good to carry the Bf-109 at up to 12 G's, which is beyond what most of the airframe was capable of handling anyway.

The Bf-109 was also known to be quicker at high speed pullouts than most other a/c, P-51 pilots in a number of incidents finding themselves unable to pullout from high speed dives as quickly as the Bf-109.

 

[stona]

I don't know Soren. I don't have the data. I'm only reporting what Bader said and he was definitely not an impartial witness. His question in the letter supports his position,in his experience 109 pilots tended to go easy when pulling out of a dive at high speed. He claims that he could out manouevre a 109 (presumably an E or F) when they bunted into a dive by executing a half roll(to prevent the Merlin being starved of fuel) and following them down. Again he claims that they tended to pull out rather gently and early enabling him to roll back and get into a firing psition directly behind them (no deflection).
I am not a huge fan of Bader and would always treat any of his claims with a great deal of circumspection,but that is what he said.
As regards Pringel's answers,I don't see a great deal of disinformation in his replies. Maybe the bit about Hauptmann Balthasar and A.N. Other tearing the wings off is exactly that! He certainly convinced the interrogating officer who wrote "The outstanding disadvantage of the Me109F is that the wings are not so stable as they might be. At least two pilots......have been killed in the last three weeks by tearing the wings off their 109s when trying to follow Spitfires in a snaking dive"
Of course this may be a classic case of telling your interrogator what he wants to hear.If it was a prevalent opinion in the RAF Pringel may well have gathered this from the officer interrogating him.I don't know if counter interrogation techniques were taught then, but a bit of common sense can go a long way.
Cheers
Steve

 

[dunmunro1]

Its possible that some Spits experienced wing failure but the Spit had the highest mach rating of any piston engined fighter and in at least one case the prop let go before the wings, while diving at 600mph in a Spit Mk IX.

 

[Glider]

As for the strength of the Bf-109's wing, it was atleast as strong as that of the Spitfire. So unless the Spitfire lost its wings a lot then Bf-109 didn't either. This fear of a catastrophic wing failure stemmed from experiences with the older Bf-108, and it was a well known problem. The Bf-109 featured a much stronger assembly however, and the wing was reportedly good to carry the Bf-109 at up to 12 G's, which is beyond what most of the airframe was capable of handling anyway.

The Bf-109 was also known to be quicker at high speed pullouts than most other a/c, P-51 pilots in a number of incidents finding themselves unable to pullout from high speed dives as quickly as the Bf-109.

I am afraid that this is a statement that is often made ie that the 109 had wings that were at least as strong as the Spitfire. Unfortunately for this theory the following may be of interest:-

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

So in short No, the Spitfire didn't shread its wings on a regular basis

 

[Glider]

All
This is the second Interigation that I mentioned at the start. PLEASE NOTE that this is a pilot who was flying a 109E not a 109F.

Points that caught my eye
1) He was on his first war flight over England
2) There seems to be a lot of emphasis on the number of war flights a Pilot had done, this is a phrase that was new to me.
3) He only seems to have made pilot grade due to influence in the Party not because of his natural ability
4) This may have been his forst war flight over England but he had instructed for some months prior to this
5) Diving practically vertically was considered an effective evasion method
6) One of the problems with this were the number of aircraft lost by diving into the ground
7) Pilots avoid turning battles
8) The comments of training and States of Readyness I found interesting

As before the quality of the docs is marginal, any problems please let me know and I will do what I can