fw 190a5 flight model

[Gaston]

Originally Posted by JtD

The Spitfire stall speed is lower and therefore it turns better at low speed. In fact it can still turn at speeds at which the Fw 190 can't even fly straight any more.

Well my theory, assuming you understand it, explains perfectly well why stalling speed is unrelated to the maximum low-speed sustained turn rate (which is not found by trying to turn near the straight-line stall speed: The maximum sustainable turn rate is quite a bit above that in all aircrafts)...

It seems stalling speed is unrelated to low-speed sustained turns (which is why the Ki-100 performs so dramatically better than the Ki-84 in sustained turns), just like high speed dive pull-outs are unrelated to low-speed turning, but on the other hand high speed dive pull-out performance does correlate with stall speed quite well. It should; the prop disc load is reduced in the dive by faster incoming air, reducing its influence, and, like the straight-line stall, there is is no slower incoming air in the top prop disc portion to create an assymetrical load...

The FW-190A has exactly the pathetic dive pull-out performance that one would expect for its stall speed, which also correlates well with its high wingloading.

The FW-190A is the only fighter for which Eric Brown states "Killing speed by sinking imposes a Tactical restriction when pulling out from low-level dives".

It is also the only fighter for which I have ever read: "Will fall another 220 m after leveling out from a 40° dive of 1200 m"... In other words, falling hundreds of feet nose level or nose up, causing a huge vertical deceleration and thus "a tendency to black-out the pilot" (P-47 front-line test)...

It also happens to have one of the highest stall speeds of all WWII single engine day fighters...: 120 MPH...

High speed horizontal unsustained 6G turns are slightly less correlated with stall speed, but still correlates very well because higher Gs "drown out" the effects of the prop's assymetrical load in turns, in the case of the FW-190A emphasizing its heavier airframe weight proportionately to an unchanging or reducing prop load effect (faster speeds mean more air hitting the front of the blades, thus reducing the blade load)...

To the left, the FW-190A's high speed turn is acceptable, but still poor in high speed/High G left turns, but its turn performance is truly abyssmal in high speed/high G right turns. The assymetrical wing drop and prop rotation high speed spiral has a bigger effect at high speeds.

At high speed the FW-190A is thus barely acceptable in hard left turns, but often snaps out entirely in hard right turns.

That this high speed's poor turn/dive pull-out performance is so clearly consistent with the FW-190A's high wingloading does not explain why at low speeds its sustained turn performance is so much better, at least if you ignore my theory.

Also, if you ignore my theory, there is no explanation why the the FW-190D has a much poorer sustained turn performance, or why laying off the throttle will improve wingloading, in a curve, but not in a straight line stall. (In a dive pull-out, the faster incoming air has the effect of reducing the prop load, and thus the comparative effect of the pull-out's curve compared to a "real" curve from a horizontal turn)

Gaston

P.S.

The FW-190A's flaps, when down, reverse the effect of the prop spiral airflow at low speeds, probably because being closer to the prop they have more effect than the impact on the more distant tailplanes, and their location has a different leverage on the airframe.

Also at low speeds, in the effort of maintaining speed in a turn, the engine torque has more effect compared to the airflow, and acts opposite the prop's airflow spiral rotation, not with it.

Unlike at high speeds, at low speeds the FW-190A's turn stall assymetry is thus less, given the lesser prop spiral airflow influence at low speeds.

G.

[Glider]

Originally Posted by K_Freddie

...at low speed, just above the stall. This is where Gaston is making his point.

The problem here is that its only Gastons point. No one else of any nation including the Luftwaffe agree with him. No pilot, no test result, no one, its only Gastons point.

Everyone is going 'No ways, it can out turn them as all the flight comparison tests have been done' - I'm also yet to see an official WW2 low speed turning comparison. That Russian report might be the closest that we'll ever get..

Any continious turn will develop into a slow speed turn as the aircraft bleed energy

BTW .. online the one time I had a Spit, probably a IX, on my tail when I slowed down to full flaps and 50-100ft above the ground. I went into a gentle right bank and he followed, I then threw it into a full hard RH turn at full throttle and right rudder. The Spit couldn't follow - maybe the pilot or maybe the FMs might be correct.

Interestingly you did the one thing that I would expect to work. One area that the 190 had a clear and significant advantage over the Spit is in its roll rate. By suddenly increasing your turn the SPit would find it difficult to keep up. You would be well into your turn while he is still trying to get into a position to begin to turn. You may want to try reversing your turn in a barrel roll by barrel rolling to the right, going over 270 degrees and then turn in the opposite direction to the one the Spit would expect.
In all these cases you would gain a few precious seconds and possibly get the drop on him.

[K_Freddie]

Actually there was not much rolling to do.. I think it's more about the torque effect (not the prop-wash) of the inline vs the radial. I vaguely remember in one documentary that a P51 pilot mentioned that if you wall the merlin throttle it could flip the aircraft over while still on the ground, he over-emphasized gentle throttle application - such was the power of inline torque effects.

The game merlin gets very touchy at slow speeds where as the DB801 is quite tame and easier to control. I've seen many an unsuspecting Spit pilot plough into the ground behind me...

It is controllable, but seemingly not at the FW190s turn rate at stall speeds.

[IceFire]

Originally Posted by K_Freddie

I am just pointing out the error in the 'document', which does not seem to come from a pilots POV. Pilots can be dimwits, but to get the prop-rotation wrong, is from a pongo/groundhog/political commissar.
And... yes I read that doc, and have highlighted this error elsewhere!

The part that is missing is exactly when the pilots were consulted on this. Since left/right is a 50/50 thing it's easy enough for the pilot to remember that they were always catching 109s in a left or right handed turn but mixing up the direction. Plausible.