Spitfire structural failures

[Crumpp]

To be honest I think it is rediculous how any Spit thread had to degenerate into how the LW aircraft were better, and any 109 thread has to become how the US or RAF aircraft were better.

That is the truth.  3/4 of this Thread has been good.  I've learned a few things.  The other 1/4 is crap.  


Crumpp

[gripen]

Originally posted by mw
Hi Gripen:  “the Bf 109 developed strong dutch roll motion above it's critical mach number which is about mach 0,76 according to German documentation and that fits also quite nicely to it's dive limits.”

I have a report by Gen. Kaithel  (sic) drawing on TAGL II Bf 109, A.1, Nr 1 lfd. 675/43 and the experiences of the Rechlin’s Beauvais wherein flight characteristics and limits of the 109 are described:   In the fighters at present in service, difficulties (compressibility) appear above all in the behavior of the elevators (...) at M = .76 .     The behavior of the 109 around its high axis deserves special attention.  With a free rudder the 109, particularly with blister armament and chiefly at great altitudes in high speed dives, tends to swing like a pendulum around its high axis, combined with a rolling movement.   The only correct thing to do is to counter this movement with the rudder (not with the ailerons).  On account of this peculiarity, trifles such as, for example inconvenient position of the pedal and in particular incompletely trimmed ailerons and rudder ruin the feel of the aircraft to uselessness.

Hi mw, these instructions are very similar as in the Finnish documentation; lateral oscilations must be countered with rudder only, using ailerons would cause increasing oscilations. In addition documentaion instructs pilots to trim the plane to need a bit push to keep it in dive, if the needed push force starts to decrease then the speed should be decreased or increasing dive tendency will follow.

gripen

[mw]

Hi Gripen:  That's very interesting.  Wish I could read Finnish  Heck, I wasn't sure what a Dutch roll was.  I thought that  the pendulum motion combined with the roll described in the report might be the Dutch roll you mentioned.

"using ailerons would cause increasing oscilations."  Ahh, that's logical.  I was thinking that instruction was because the ailerons might fail if used in a dive, (Harte querruder betätigung im Sturz und besonders beim Abfangen führt zum Bruch.)
.

[MiloMorai]

Crumpp, you have had your share threads degenerate because of you, ie. the LW destroyed thread for one. Stop calling the other kettle black. Yes you have had your share of some of that 1/4 in this thread.
 
Tell Barbi to stop making his slanderous posts and then I won't have to comment. See the 1st line in his first post in this thread. If he had conducted himself in a civil manner from the start(Onwar), all would be fine. He is not just adversarial with just me or have you not noticed?

...........................

Now it is nice to see some intelligence shown in the 2 posts on WW2 a/c. Time will tell if what he says is a snow job, or he can live up to.


Something for you to file away. The P-51 pilot was not to use trim to pull out of a high speed dive. He was to gently pull back on the stick.

[Crumpp]

Gripen and mw,


Didn't they increase the height of the 109 tail as a result of Schimd's dives.  I want to say it was either 135mm or 138mm.  Don't rember and don't have time to look it up.  

This was done to make the 109 easier to recover.

Does anyone know if the G6 and G10 in AH have the "tall" tails?

Crumpp

[VO101_Isegrim]

Originally posted by Crumpp
Gripen and mw,


Didn't they increase the height of the 109 tail as a result of Schimd's dives.  I want to say it was either 135mm or 138mm.  Don't rember and don't have time to look it up.  

Crumpp

IIRC it was increased as you say. Increasing the vertical tail surface area increases wheatercock stability. This in turn decreases the adverse yawing movements which result in assymetric loads on the fuselage. That`s why HARD aileron (or hard rudder inputs) movements are generally not advised during dives, ie. they come with a yawing movement, which loads the tail greatly on one side and it may break. But if you increase the tail area, stability is better, and less aileron deflection is sufficient for the same rate of roll obtained, therefore there`s even a reduction of aileron forces at high speeds and increase roll rates.

This 135mm bigger tail unit become serialized on the 109G series.

[Furball]

Originally posted by GScholz
The entire horizontal stabilizer was moved by the trim-wheel in the cockpit.

ahh i see! thanks!  it has a fixed rudder trim tab too

[Angus]

Did the rudder trim enter with the 109F?

[VO101_Isegrim]

Originally posted by Angus
Did the rudder trim enter with the 109F?

No Bf 109 had cocpit-adjustable rudder (or aileron) trim, however all had ground-adjustable trim tabs on all control surfaces. Flettner-tabs were introduced with the tall tails for the rudder in 1943, but this was to lighten control forces at high speeds.

There was no elevator trim either, but the whole tail incidence could be set from the cocpit with that trimwheel, on all combat versions. In fact, this was much better in view of compressibilty control problems, since the while horizontal plane was effected, not just to elevator area.

[Angus]

The 109 the Brits captured (1940) did not, as far as I know, have any kind of rudder trim. I've heard that from some other source, but it may have been the same aircraft. Hence the question

[Angus]

So, when was the entry of rudder trimmed 109's?

[MiloMorai]

Originally posted by Angus
So, when was the entry of rudder trimmed 109's?

You are asking about pilot rudder trim > they never did. All they got was the Flettner tab so the pilot did not get a 'fat leg' as he did on earlier versions.

[Angus]

Ah, misread Isengrims informations, sorry.
(it was a "no" instead of "the")

The downside of fast reading

[Angus]

Getting back to the original topic of airframe strength.
The Spitfire (Mk V) airframes that broke due to enormous G loads caused by instability were fully strong.
The G loads they were exposed to would have broken ANY WW2 Fighter, many of them quicker. It has been said that the loads may also have killed the pilot.

[Charge]

"The G loads they were exposed to would have broken ANY WW2 Fighter, many of them quicker"

I'm quite sure you are right, Angus.

The Spitfire had a very strong main spar runing through the fuselage from wing to wing and it was made of square pipes inside the other which made it very durable. I know no other a/c which had a similar separate main spar in the wing.

Correction: there was a picture of a XIV showing the bolts of the main spar so I had bad info on that. So it didn't run through the fuselage but it was of very durable design anyway.

-C+