helicopter

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helicopter Aircraft that gains lift from rotors (rotating aerofoils), and is capable of vertical takeoff and landing, hovering, and forwards, backwards and lateral flight. At take-off, all blades have a steep pitch in order to achieve maximum lift. The circular movement of the blades generates an opposite, reactive force on the helicopter that is overcome by another set of opposite-turning rotors, or by another small rotor in the tail generating thrust in the opposite direction. Igor Sikorsky (1889–1972) built the first successful helicopter in 1939.

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