Bf109F vs P-38F

[Aussie1001]

meh good enough....

[Soundbreaker Welch?]

That's a good point. In timewise, a P-38J wouldn't be fighting a BF 109F, but more likely a Bf 109G?

[flojo]

I find these discussions about the lacking qualities of the 109G a little bit of a problem as the different g-subtypes differ so strongly. G2 was more similar to the F-models in my opinion than to the G6. And also a late G6(+MW50)/G14 or one of the types with AS or D engines with better high altitude chargers were quite different than an early 1943 G6.

[superpumper]

I might be wrong but I think I read somewhere that the 109 could lose its wings in combat in very tight turns if one wasn't careful at least in the early models. Is this so?

[trackend]

I,ll go for the 109f.
Not that this threads about it but I'd like to have seen what the 309 could have done slower but with two 30mm two 20mm and four 13mm pretty devastating

[DerAdlerIstGelandet]

Originally Posted by superpumper

I might be wrong but I think I read somewhere that the 109 could lose its wings in combat in very tight turns if one wasn't careful at least in the early models. Is this so?

Early versions of the Bf 109F had problems with vibrations which could make the wing surface to break apart. This however was fixed very quickly.

[mkloby]

Originally Posted by DerAdlerIstGelandet

Early versions of the Bf 109F had problems with vibrations which could make the wing surface to break apart. This however was fixed very quickly.

I believe I remember reading that at a certain RPM range the empennage (horizontal stab I believe) would suffer catastrophic failure due to sympathetic vibrations.

[Glider]

Originally Posted by mkloby

I believe I remember reading that at a certain RPM range the empennage (horizontal stab I believe) would suffer catastrophic failure due to sympathetic vibrations.

I have heard this before on other threads, but on the thread about Gunther Rall, the following statement of his caught my eye.

Anyway, I was chased by P-47. I knew exactly that in a dive P-47 is much faster than 109. And the P-47 has a much higher structural strength. They can go up to 1400 kilometers per hour. The 109, if you go to 1000, pull it up, you risk that the wings come off.

If Gunther was cautious of the wings coming off, then other less experienced pilots must have experienced a wing failure. This proves to me anyway that the problem was more widespread than just 109F vibrations

[Kurfürst]

Any wing will fail after the dive limitations are exceeded, or if the ailerons are badly set up. The 109's 'problems' with wing failures were not any more pronounced than your avarage WW2 fighters. It happened, from time to time, the usual culprit was the pilot exceeding the Vne, badly set up ailrons or simply worn-out, old airframes. Usually the problem was not as much the lack of structural strenght, but that conditions could arise which grossly overloaded the wings. No WW2 fighter's wing was built to resist twisting movements, for example, you will find the NACA making such reports with regards of the P-47 Thunderbolt.

Certainly there were quite a few fighter types more notorious for these kind of troubles than the 109.

[Konigstiger205]

The 109 was not the most excellent fighter in WW2 but it did its job and in the hand o experienced pilots it proved a very deadly plane and the numbers in which was produced shows as much.

[Glider]

Originally Posted by Kurfürst

Any wing will fail after the dive limitations are exceeded, or if the ailerons are badly set up. The 109's 'problems' with wing failures were not any more pronounced than your avarage WW2 fighters. It happened, from time to time, the usual culprit was the pilot exceeding the Vne, badly set up ailrons or simply worn-out, old airframes. Usually the problem was not as much the lack of structural strenght, but that conditions could arise which grossly overloaded the wings. No WW2 fighter's wing was built to resist twisting movements, for example, you will find the NACA making such reports with regards of the P-47 Thunderbolt.

Certainly there were quite a few fighter types more notorious for these kind of troubles than the 109.

I have never heard of this problem being mentioned on other fighter aircraft.
Certainly I have never heard of an experienced pilot of a fighter be limited in his actions by the fear of such a wing failure.
I also find it hard to believe that such a top pilot would have badly set up ailrons or worn out airframes.
Can I ask you to name any examples of other aircraft with similar problems?

I also notice that on the JG26 web site the following phrase

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".

No one would deny that the other types of accidents are common to all airforces, but again, I have never seen wing failure mentioned in the context of a normal accident. Again have you any examples?

It would appear that it was more common on 109's and 190's.

[drgondog]

Originally Posted by Glider

I have never heard of this problem being mentioned on other fighter aircraft.
Certainly I have never heard of an experienced pilot of a fighter be limited in his actions by the fear of such a wing failure.
I also find it hard to believe that such a top pilot would have badly set up ailrons or worn out airframes.
Can I ask you to name any examples of other aircraft with similar problems?

I also notice that on the JG26 web site the following phrase

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".

No one would deny that the other types of accidents are common to all airforces, but again, I have never seen wing failure mentioned in the context of a normal accident. Again have you any examples?

It would appear that it was more common on 109's and 190's.

Both the 51 and 47 experienced structural failures including wings (and tails) during dives. In the case of the 51 and 47 the tail failures were mostly (not all definitively) a result of yaw in the dive..

The 51B/C wing issue was 'mostly' solved with uplock kits to keep the wheel well door from spring loose as well as stiffer ammo doors which were believed (not conclusively) to 'flex', creating more local lift loads at that critical area.

The latter analysis was mored complicated because it wasn't conclusive that the issue was higher Center of Lift loads inboard or disruption of flow rendering horizontal stabilizer less effective causing nose down pitch (ala Me 262 'departing' at Mcr in a dive- ditto P-3 at very high speeds.

The D fixed (mostly) both of the wing problems and the H fixed (mostly) the high speed yaw problem. Both of these also had metal elevators.

Having said that, both the 51 and 47 had a stronger wing than a 109, maybe because they were both designed to carry pretty heavy wing armament and landing gear loads at mid-point of wing spar.

That design and subsequent structural approach had a lot to do with the 109's issue in adding more and heavier armament Internal to wing..namely main gear close to fuselage and all armament internal to nose.

[drgondog]

Originally Posted by mkloby

I believe I remember reading that at a certain RPM range the empennage (horizontal stab I believe) would suffer catastrophic failure due to sympathetic vibrations.

That's interesting.. Resonance and effects w/AeroElasticity were not very well understood sciences until the Comet started failing in the 50's.. I wonder what triggered Messerschmitt to solve the problem?

I'm also wondering, even more, what the natural frequency of the 109 wing might have been as the RPM of the engine would be one of the prime 'input factors'.

You would have to make some serious changes to airframe structure of the wing to change the natural frequency - or change the RPM dramatically (which didn't happen).

Jes ponderin' what all that might be about...I just don't recall ever seeing anything regarding structural failure due to either resonance or fatigue until post war for an airplane.

Von Karman proved that alternating vortices shed in such a way from the cables suspending the bridge (Washington State??1930's?? CRS) that at a specific wind speed and loading on the bridge, that the frequency of the vibations of the cables resonanated with the natural frequency of the bridge and it 'departed' - does anyone know of a specific aircraft study on this before 1950's?

[FLYBOYJ]

Even today certain aircraft cannot be constantly operated in some RPM ranges - I know it's just bugsmashers but 300 HP Piper Cherokees should avoid continuous operation between 1650 and 1900 RPM above 24" MP and 150 hp Cessna 150s have to avoid RPMs bewteen 1850 and 2250 RPM in a desent...

[Kurfürst]

Originally Posted by Glider

I have never heard of this problem being mentioned on other fighter aircraft.
Certainly I have never heard of an experienced pilot of a fighter be limited in his actions by the fear of such a wing failure.
I also find it hard to believe that such a top pilot would have badly set up ailrons or worn out airframes.
Can I ask you to name any examples of other aircraft with similar problems?

Oh, basically the more you dug into the history of an aircraft, the more you read of troubles, failures and the like. More skeletons of in the cupboard. Development of an aircraft is basically fixing these problems. I recommend you trying to get some really through books on aircraft development, like Spitfire : The History. You'll find plenty of examples of the like in it.

Take a look at this one :

http://i38.photobucket.com/albums/e1...rst/spits2.jpg

Though I could list you certainlymany more examples than you'd consider friendly

There are many others, as I said, structural failures due to various reasons were rather not uncommon for WW2 aircraft. And, usually it was not much of a matter of structural strenght but aerodynamics. Ailerons play a huge role in it, just look up 'flutter' effects. There was little in the hands of 1940s engineers to forecast those effects they knew little about in the first place.. so, accidents happened, wings failed, and they tried to fix that by trial and error methods.

I also notice that on the JG26 web site the following phrase

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".

It seems to be a total for all causes without any way to know what was the breakdown. (getit?)

It would appear that it was more common on 109's and 190's.

I don't think we have sufficient, comparative evidence to make a statement like that in good faith.