A helicopter is an aircraft that is lifted and propelled by one or more horizontal rotors, each rotor consisting of two or more rotor blades. Helicopters are classified as rotorcraft or rotary-wing aircraft to distinguish them from fixed-wing aircraft because the helicopter derives its source of lift from the rotor blades rotating around a mast. The word 'helicopter' is adapted from the French hélicoptère, coined by Gustave de Ponton d'Amecourt in 1861. It is derived from the Greek words helix/helik- ( ) = "spiral" or "turning" and pteron ( ) = "wing".

As an aircraft, the primary advantages of the helicopter are due to the rotor blades that revolve through the air, providing lift without requiring the aircraft to move forward. This creates the ability for the helicopter to take off and land vertically without a runway. For this reason, helicopters are often used in congested or isolated areas where fixed-wing aircraft cannot take off or land. The lift from the rotor also allows the helicopter to hover in one area and more efficiently than other forms of vertical takeoff and landing (VTOL) aircraft, allowing it to accomplish tasks that fixed-wing aircraft cannot perform.

Although helicopters were developed and built during the first half-century of flight, some even reaching limited production, it was not until 1942 that a helicopter designed by Igor Sikorsky reached full-scale production,Munson 1968 with 131 aircraft built.Hirschberg, Michael J. and David K. Dailey, "Sikorsky." US and Russian Helicopter Development In the 20th Century. American Helicopter Society, International. 7 July 2000. Even though most previous designs used more than one main rotor, it was the single main rotor with antitorque tail rotor configuration of this design that would come to be recognized worldwide as the helicopter.

History

Since 400 AD, Chinese children have played with bamboo flying toys. This toy made its way to Europe and is depicted in a 1463 European painting.Goebel, Greg. "The Invention Of The Helicopter". Vectorsite.net. Retrieved: 28 November 2007. A book written in 4th-century China, referred to as Pao Phu Tau (also Pao Phu Tzu or Bao Pu Zi, 抱朴子), is reported to describe some of the ideas inherent to rotary wing aircraft:Fay, John. "Helicopter Pioneers - Evolution of Rotary Wing Aircraft". Helicopter History Site. Retrieved: 28 November 2007.

cquote: Someone asked the master about the principles of mounting to dangerous heights and traveling into the vast inane. The Master said, "Some have made flying cars with wood from the inner part of the jujube tree, using ox-leather 1 fastened to returning blades so as to set the machine in motion."