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, type of aircraft supported in the air by a horizontally mounted airfoil similar to that of a helicopter but unpowered. Invented by the Spaniard Juan de la Cierva, it was first flown successfully in Jan., 1923, in Spain.
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A rotorcraft whose rotors are not power-driven.
A heavier-than-air rotorcraft whose rotors are not engine-driven, except for initial starting. They are made to rotate by the action of the air when the rotorcraft is moving. The aircraft's means of propulsion, consisting usually of conventional propellers, is independent of the rotor system. Also known as an autogiro rotorcraft.