RE: what is aileron flutter?
Google up "aeroelastic flutter". The cause is the center of lift ahead or the center of gravity on a control surface. The solution is to lighten the trailing edge ("back to the drawing board") or add weight at or ahead of the leading edge. You'll see full-size planes with weights on the end of struts or with small surfaces out on the ailerons called "spades" that have a flutter-reducing effect.
Many full size aircraft have an internal weight attached to a control surface that goes into the wing or fixed empennange to reduce flutter without being visible (or adding drag) outside of the plane. That does limit the throw available