A newbies impression of the 109 and spit

Originally Posted by winny

I'm not arguing the physics. At all. I'm also definitely talking combat.
I'm highlighting the fact that context is important too.

History is important, i've read of at least 2 RAF pilot's intentionally spinning as a way to lose altitude whilst being shot at, and I think at least 1 LW guy. I'd have to check thru piles of books...

I'm sure that plenty of pilot's were killed by their own machines failing well within the limits, after all these were hand built. I'm equally sure some went through the limits and survived. It's being made out in this thread that because the pilot's notes say that xyz will get you killed, you get killed every time. I'm merely pointing out that this is actually xyz will probably get you killed.

I maintain that pilots notes alone are not proof of anything other than recommendations. There are too many variables to simply rely on a set of instructions.

BTW what commonly passes unnoticed: it's the fact that to break up the overload has to be applied for a certain minimum time.

This is a subject that is up to now not well understood by scientists and some research is done on this aspect. But basically if something usually breaks up at Xg it may not so if the time of exposure is very very small.

You will certainly believe like me that 30g is something human bones do not withstand, don't you.

Now you know that acceleration is delta(v)/delta(t) with v being the instantaneous velocity and t time.

Now when I jump from a chair my velocity will be not zero, let's say it is about 2 m/s right before I touch the ground. Now when touching the ground the velocity is reduced to zero, so delta(v) = 2 m/s. This happens basically instantly that's why delta(t)<<1. Which will make the acceleration incredibly high. Delta(t) just needs to be smaller than a millisecond to have a decceleration of 200g. Of course my reflects will absorb the shock but even if I'd just fell to the floor or jumped with stiff legs I would not break them. As much as I can break a plastic spoon easily with my two hands without much effort while it won't break if I threw it with force to the ground.

I for my part as an engineer and scientist am much thrilled and fascinated by this kind of intriguing phenomenon.

Of course this whole thing highly depends on the material as from daily experience I would say that elastic materials can take this ultra short loads much more easily than brittle material.

I guess that the lower the overload the longer the exposure times. So it is not unthinkable that if the overload was only for a little time the plane still might have survived it even if the book told that this never was going to happen.

Also remember that the limits for which the planes were designed were theoretical values based on experimental data on material properties obtained through probe measuring and some hand formula and sort of thump rules. These values also contained a certain margin that was dimension by some regulatory rules based on more thump rules.

No finite element methods back then.

Obviously a pilot would not or only in dispair engage in a manoeuver that he would be certain to break his plane with. Nevertheless his plane might not have broken up against all odds, if he was really lucky.