The sharp edge of the aft wing will cause flow to separate at low aileron deflection angles. For maximum aileron control the ailerons should be thicker then the wing so that flow reattaches after crossing the gap between wing and aileron. Another approach that is used on full size aerobatic planes is to hinge the aileron at about 30% chord so that the leading edge of the aileron is deflected up above the trailing edge of the wing... If you look at the Extra 300's and Sukhoi's you'll see this design.

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