A helicopter is an aircraft which is lifted and propelled by one or more horizontal rotors. Helicopters are classified as rotary-wing aircraft to distinguish them from conventional fixed-wing aircraft. The word helicopter is derived from the Greek words helix (spiral) and pteron (wing). The first single-rotor, fully-controllable helicopter to enter large full-scale production was made by Igor Sikorsky in 1942.

Helicopters are widely used by the US Army, Air Force, and Navy as well as by agencies such as the FBI.

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