Frise Ailerons

A type of aileron used for lateral control of an airplane. The hinge line of a Frise aileron is set back from the leading edge so a portion of its surface is ahead of the hinge line. When the aileron is raised, to lower the wing on which it is mounted, the portion ahead of the hinge line protrudes below the wing and causes parasite drag. This parasite drag counteracts the induced drag produced on the opposite wing when its aileron is lowered. Frise ailerons minimize adverse yaw.