AOA indicator

On Thursday, April 14, 2016 at 6:05:36 AM UTC-5, Bruce Hoult wrote:
On Wednesday, April 13, 2016 at 9:54:17 PM UTC+3, kirk.stant wrote:
Well, you're right that it's basic aero, but you've somehow managed to get it backwards.

Both wings are descending through the air at the same speed (or you'd be rolling). The inner wing is travelling less distance therefore the angle of attack is greater.

Unless you are spinning, I doubt the difference in distance has a greater effect than the effect of yaw on the effective AOA of each wing. Once you are in a spin, then the inside wing is definitely at a higher AOA and stalled (which is pretty much the definition of a spin).

Looking at it another way, the inner wing is travelling slower but has to generate the same amount of lift, therefore its angle of attack must be greater.

Only if you want a constant bank. Which is why you either have to use top aileron against the overbanking tendency, which increases the camber of the bottom wing, or top rudder to increase the AOA via yaw. If you bank and do neither, the top wing will make more lift and you end up in a spiral.

Stable slips or skids and dihedral don't make any difference to this. Of course if you kick in some yaw then at the moment the speeds and distances traveled will be different. Putting in some slip/top rudder will accelerate the bottom wing and (briefly) take it to a lower AoA -- and possibly even out of stall if it was a little bit stalled.

Any wing with dihedral (or sweepback) will roll if held in a steady yawed condition with positive AOA held. Not very effective in the typical glider, but in something like an F-4 or F-15, you can do nice 4-point rolls using only back stick and rudder.

But I'm only an amateur aerodynamicist, any experts out there to explain how I'm wrong? Always willing to learn... ;^)