Negative flaps for better low speed aileron control?

On Fri, 29 Jul 2005 17:31:08 UTC, wrote:

: Will someone please explain why negative flaps supposedly
: provides better aileron control.

Here's a guess.

At low speeds on the ground, the wings are very near their stalling
AOA. If on wing does start going down, for whatever reason, the
additional vertical movement may cause it to increase its AOA beyond
stalling. Hence much reduced lift on that side, lift still being
produced on the other side, rolling moment, wing goes down faster. An
unstable situation.

By using negative flap you are effectively reducing the AOA of both
wings. Now a downward movement is less likely to lead to stall, and
more likely to lead to an increase (but sub-stall) AOA at the same
speed, so more lift and back up comes the wing. A stable situation.

This is all guesswork, since I don't fly flapped gliders. I'd expect
my explanation to work best on gliders with high wing loadings and
relatively high angles of attack sitting on the ground. Does that fit?

Ian
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