The Convertoplane, cross between an airplane and a rotorplane, was developed in the United States in the 1930s by the "father of the convertoplane," inventor Gerard P. Herrick, aided by Ralph H. McClarren of Philadelphia's Franklin Institute. Basically, the design was a biplane with an upper wing that could function either as a lifting surface or as a two-bladed teetering rotor. Flown by test pilot George Townsend in 1937, the aircraft demonstrated successful conversions in flight from a biplane to a rotorplane. Herrick was striving for an aircraft that could achieve speed as an airplane while possessing ability to convert to rotating-wing configuration for landing and take-off in tight areas.

C.Gablehouse "Helicopters and Autogiros", 1969