U.S. Patent Specifications

In an aircraft, a main supporting surface, auxiliary pilot aerofoil means, and propeller means adapted to produce a slipstream substantially immersing a portion of said main supporting surface, said auxiliary aerofoil means comprising a plurality of sections disposed longitudinally of the span of said main supporting surface certain of said sections being fully immersed in said slipstream and arranged for independent movement at each side of the propeller axis whereby they move independently and respectively in the upward and downward swirl produced in the slipstream by the rotation of said propeller, others of said sections being substantially free of said stream, and stop means adapted to limit said sections to a position of maximum effect.