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Old Jan 06, 2013, 11:46 PM
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Target, I agree that when flying faster (low CL) less "stuff" is needed and understood that part of your statement. What I highlighted was your mention of "extra diff" and "less rudder", which seemed to indicate a preference toward differential even when outside of the stall regime. I didn't intend to take your statement out of context but even with your clarification I still see this interpretation. Again, the partial sentence in reference to V-tails seems to convey the same point: "...rudder mix is a bad thing when you can use some diff instead." To which I'll note that while V-tails are certainly less efficient at producing yaw forces than cross tails they are still more efficient than aileron differential which acts as both a drag brake and a spoiler. And yes, an ail-rud mix with a V-tail produces a roll force in the opposite direction, but still, it's more efficient than scrambling the wing's lift distribution and deploying speed brakes.

A rising aileron most certainly reduces drag and you know this -- that's why I reminded you with the "(reflex)" reference. Drela points out that the major cause of adverse yaw is usually lift vector rotation, much to our surprise, but this doesn't mean that aileron effects are insignificant, they may be nearly so with a good F3J pilot, but in other cases (F3F for example) aileron input is frequent and so the induced and profile drag effects of the aileron can be very significant.
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