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Old 11-16-2012, 08:40 AM
Herra Tohtori Herra Tohtori is offline
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Quote:
Originally Posted by MaxGunz View Post
And then they both pull and hold a hard turn. Which one reaches stall first?
They both reach stall at the same angle of attack (assuming, as with earlier premises, that the wing chord profile is the same and only difference is wing area). There is not such thing as "stall speed".

However: If starting airspeed is the same, and both aircraft start turning on the exact same trajectory - same turn rate, same turn radius, then the following applies:

Both aircraft need equal amount of lift to stay on equal trajectory.

As velocity is the same initially, and the only difference on planes is wing area, that means angle of attack must be different between the planes.

That means that the aircraft with smaller wing must hold higher angle of attack to travel on the same path than the larger wing aircraft.

This will, of course, quite fast start making a difference on where on the path the airplanes are. Because the small-winged aircraft needs to pull higher AoA to stay with the other version, it ends up having much more drag, and assuming both planes are having their engines balls to the wall that means the small wing aircraft will start losing energy in the turn much faster than the large winged aircraft.

As the small winged aircraft starts losing speed, it also starts losing lift and thus turning ability, and it needs to start pulling even more angle of attack until critical angle of attack is reached.

In this exercise, it is fairly likely that the aircraft with smaller wing will reach its critical angle of attack first if it tries to stay turning with the other aircraft.

Additionally, if we are to assume that the large wing aircraft starts pulling the turn exactly at the critical angle of attack to begin with, then it is quite impossible for the small wing aircraft to even stay with it on the turn, because it cannot increase its own angle of attack higher than the critical AoA, and stalls immediately at the beginning of the turn - or ends up on a wider turn than the large-wing aircraft.

This, personally, I can confirm with great satisfaction in IL-2.


Quote:
The stall speed multiplies by the square root of G's pulled resulting in a greater difference between the planes -- from high speed start it will be the one that runs out of smash first.
Did I mention that the concept of "stall speed" is something I personally find rather annoying?

Stall speed is an indicatory value for pilots and only holds at level flight. Aircraft can stall at any speed when thrown around with fists of ham.

Stall speeds are given as the speed at which the aircraft can JUST hold its own weight with its lift, without losing or gaining altitude or airspeed, and holding angle of attack at or very near critical AoA.

It gives some idea of the aircraft's performance since the stall speeds can be compared, however its relation to turning performance is not necessarily 1:1.


Quote:
However the claim that a 190 should out-turn a Spit at low speed fails right there as you would have to defy physics or have a very poor Spit pilot in the Spit and a very good 190 pilot in the 190 to do so and then we are no longer comparing just the planes.
Take away knowing who is flying which plane (and most other details) and we have a war story to misuse and come up with ignorance-based 'data'.
Amen.

However we can probably both agree that as the FW-190 was introduced it had great successes against the contemporary Spitfires for various reasons, which could be listed but have already been mentioned in the thread.

"Better turning ability" is decidedly not one of them, but the otheres - higher speed, excellent visibility, easy operation of engine to get the most out of it (Kommandogerät love) while Spit pilots had to dick around with engine settings... All of these could easily have made plausible situations where a FW-190 (or entire group of them) "outmaneuvered" Spitfires, using energy tactics, team tactics, and surprise of Spit pilots at finding entirely new aircraft that they've never seen before.

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The real cool stuff happens at higher speeds where turn fighters can't turn so hard without losing speed. The best energy fighting tactics use that whether online or IRL, check with Robert Shaw if you think different. At speed the 190A is booja but then 'at speed' in a 190A is 'high speed' in a Spit V.
Yeah, at transient turns (rather than sustained turns) there are some different factors to consider. An aircraft's transient turn rate basically depends on how fast it can dump energy into direction change, whereas sustained turn rate depends on how fast the engine can produce energy to compensate for drag losses, keeping the airspeed constant (and with that, turn rate and turn radius).