An NACA 64 3-621 reflection-plane airfoil panel equipped
with a 38% chord aileron was tested in the WSU 7 X 10 ft. Walter Beech Memorial Wind Tunnel.
Combinations of three different designs of ailerons and six aileron hingelines were tested with the aileron in the 90 degree up position. An optimum combination of aileron and hingeline was chosen which produces negative c5 (negative torque for an untwisted, zero pitch wind turbine blade) at all angles of attack from zero to more than 50 degrees. A second series of tests was conducted on the NACA 64 3 621 reflection-plane panel for the optimum combination of aileron

and hingeline position at various angles of aileron deflection from zero to 60 degrees. Also tested at small angles of aileron deflection was an NACA 23024 airfoil reflection-plane panel. The aileron­ hingeline combination had been previously optimized for this airfoil.

For both airfoils the optimum hingeline location produces a gap be ween the airfoil and the aileron leading-edge. Flow visualization studies show that the gap provides a path for flow from lower surface to upper surface at high angles of attack. It is believed that this flow contributes to the success (in producing negative Cs ) of the deflector-aileron control device.