A helicopter is a heavier‐than‐air aircraft that is supported in flight primarily by the reactions of the air on one or more power‐driven rotors on substantially vertical axes. Helicopters are classified as rotorcraft or rotary-wing aircraft in order to differentiate them from fixed-wing aircraft. While aircraft achieve lift from their wings, helicopters achieve lift with rotor blades which rotate around a mast.
The primary advantage of a helicopter is that the rotor provides lift without the aircraft needing to move forward to generate lift. This allows the helicopter to both take off and land vertically without the need for a runway. It is for this reason that helicopters are often used in congested or isolated areas where fixed-wing aircraft cannot take off or land. The lift from generated by the rotor also allows the helicopter to hover in one place, something not fixed-wing aircraft are not capable of. In addition helicopters can hover more efficiently than other forms of vertical takeoff and landing (VTOL) aircraft, which allows it to perform maneuvers that fixed-wing aircraft cannot.
Helicopters were first developed and built as early as the first half-century of flight. Despite this it was not until 1942 that helicopters reached full scale production with 131 of Igor Sikorsky’s first helicopter being produced. His design was the first design to utilize a configuration of both a single main rotor with an antitorque tail rotor and it was this design that became known as the first successful helicopter.