an aircraft has its wing defined as a wing - like body with a tangential flow rotor in the leading edge . a shroud , under the lower part of the tangential flow rotor , terminates in at least one movable flap defining a lift - generating lip when the rotor is rotating such that the upper part of the rotor , projecting above the level of the upper surface of the wing - like body , is moving rearwardly . differential adjustment of the flaps in the wings to either side of an aircraft centerline allows directional control and control of banking of the aircraft .