Frise ailerons accomplish this differential profile drag by maintaining a smooth countour between the upper surfaces of the wing and aileron, causing very little drag, while the bottom surface of the aileron juts downward to create a large increase in profile drag. Although this approach is simple and does provide some relief, the performance of Frise ailerons is very dependent on operating conditions. For this reason, such ailerons are often only partially effective at overcoming adverse yaw. The deflection of the down aileron is typically much less than the up aileron so that the additional profile drag is very small compared to that on the up aileron. As with the Frise aileron, this differential profile drag produces a yawing motion that at least partially offsets the adverse yaw, but the effect is limited.
Spoilers are long narrow flat plates typically fitted along the upper surface of both wings.
In normal flight, they lie flat and generate no effect on the aerodynamic performance of the wing. However, they can be raised upward into the air flow generating large turbulence that reduces the lift and increases the drag on a wing. When used in coordination with ailerons, a spoiler can be used to reduce the lift and increase the profile drag on the wing with the up aileron. As a result, the wing with the down aileron experiences a large increase in lift and a small increase in drag while the wing with the up aileron experiences a large decrease in lift and a large increase in drag. These effects combine to create the desired roll motion and a complimenting yaw motion that is called proverse yaw.