A
rotorcraft or
rotary-wing aircraft is a heavier-than-air flying machine that uses
lift generated by
wings, called rotary wings or rotor blades, that revolve around a mast. Several rotor blades mounted on a single mast are referred to as a
rotor. The
International Civil Aviation Organization (ICAO) defines a rotorcraft as "supported in flight by the reactions of the air on one or more rotors". Rotorcraft generally include those aircraft where one or more rotors are required to provide lift throughout the entire flight, such as
helicopters,
cyclocopters,
autogyros, and
gyrodynes. Compound rotorcraft may also include additional thrust engines or propellers and static lifting surfaces.