[Yo-Yo]

Originally Posted by Icaro_07

Do you know Whee i can get more info about this? And hay is more complex?

At different Mach numbers the critical AoA is different. And it starts to be noticable from relatively low M - 0.3...0.4. As the trimmed AoA is quite constant up to M > ~0.7 you see the effect you mentioned.

[Vatikus]

Here is a nice article wrt AoA and what is effecting it ...
http://www.boeing.com/commercial/aer...ack_story.html

[Ironhand]

Originally Posted by Icaro_07

...but the elevator can not stall if you hold a constant position = constant AOA,..

In reading your comments, I get the impression that you are confusing pitch with AoA. The two are not identical. At any particular pitch angle, your AoA will vary with speed even though your nose (and consequently your wing) is pitched up or down by the same amount throughout.

EDIT:

Originally Posted by Icaro_07

Does any one knows if for every trim setting a stick position corresponds to an specific AOA because if it's that way it stalls at different AOA

So to answer your original question, no. Not until you take your airspeed into consideration. At a given airspeed, a given stick position will yield a particular AoA. Or inversely, a particular AoA (not pitch) with a particular stick position will give you a specific airspeed. But you can only calculate the inverse, if you know your wing's AoA. Otherwise you're missing part of the equation.

[Icaro_07]

Well is just that simplistic, fly the f-5 and for every position the stick moves corresponds to specific AOA

[Yo-Yo]

Originally Posted by Icaro_07

Well is just that simplistic, fly the f-5 and for every position the stick moves corresponds to specific AOA

Different planes have different Mach-dependant trim curves. F-5 wing is a very different thing comparing to the conventional airfoil high-aspect non-swept wing of WWII planes. Moreover, even WWII planes had very noticable differencies either in CLmax(M) or trim curves vs M.
For example, P-51 CLmax(M) had very distinctive "shelf" at moderate M, though other planes had constantly decreasing dependance. Spitfire was more preferrable regarding high-M trim changes than P-51 and P-47, tc.

[Ironhand]

Originally Posted by Icaro_07

Well is just that simplistic, fly the f-5 and for every position the stick moves corresponds to specific AOA

Are you saying that, if you hold the stick in one position, the AoA will not change even when your airspeed changes? If so, I'm not buying it. Whether in the F-15, F-5, P-51, Dora, or any other aircraft, the AoA will get smaller as your speed increases and larger as your speed decreases, if you do not change the stick position.

EDIT: But, of course, I reserve the right to be wrong...

[acdelta57]

AoA is the same principle for all aircraft. AoA is the angle between the wing chord line and relative wind. This has nothing to do with speed, pitch, roll or whatever. Each wing has a Critical angle of attack. This critical aoa will remain the same, but the factors causing the wing to reach that critical aoa may differ. Speed, bank, pitch just to name a few. This is why a wing will stall at any speed.

So to answer the OPs question, no, "stick position" has nothing to do with critical AOA. The relationship between the wing and relative wind are the only thing that will impact the aircraft and its stall. Now what you do with the stick to place the wing at its critical aoa is a different story.

[Yo-Yo]

Originally Posted by Ironhand

Are you saying that, if you hold the stick in one position, the AoA will not change even when your airspeed changes? If so, I'm not buying it. Whether in the F-15, F-5, P-51, Dora, or any other aircraft, the AoA will get smaller as your speed increases and larger as your speed decreases, if you do not change the stick position.

EDIT: But, of course, I reserve the right to be wrong...

Your statement is right only if you add "for the same lift" or "for 1 g level flight" as a part of this conditions.

Generally, for the STABLE airplane you need to push the stick forward as the speed increases to maintain this constant lift. By the way, for the neutral stability for fixed stick its position remains the same, but, anyway, you need to decrease AoA with double movement (push, then return to the same position to hold new AoA).

[Ironhand]

Originally Posted by Yo-Yo

Your statement is right only if you add "for the same lift" or "for 1 g level flight" as a part of this conditions.

Generally, for the STABLE airplane you need to push the stick forward as the speed increases to maintain this constant lift. By the way, for the neutral stability for fixed stick its position remains the same, but, anyway, you need to decrease AoA with double movement (push, then return to the same position to hold new AoA).

Yes, I had 1G flight in mind. Should have stated that. I assumed that was the case, since the OP was asking about trim settings.

[Icaro_07]

Well don't believe to me, check the F-5 trim the stick and check the AoA regardless of speed portion etc holds constant AOA