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’Amécourt in 1861. It is linked to the Greek words helix/helikos (“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 of the helicopter to take off and land vertically without the need for runways. For this reason, helicopters are often used in congested or isolated areas where fixed-wing aircraft are not able to take off or land. The lift from the rotor also allows the helicopter to hover in one area and to do so more efficiently than other forms of vertical takeoff and landing aircraft, allowing it to accomplish tasks that fixedwing aircraft are unable to perform. [Figures 1 and 2]

Helicopter flying
Figure 1. Search and rescue helicopter conducting a pinnacle approach
Helicopter flying
Figure 2. Search and rescue helicopter landing in a confined area

Piloting a helicopter requires a great deal of training and skill, as well as continuous attention to the machine. The pilot must think in three dimensions and must use both arms and both legs constantly to keep the helicopter in the air. Coordination, control touch, and timing are all used simultaneously when flying a helicopter.

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, with 131 aircraft built. Even though most previous designs used more than one main rotor, it was the single main rotor with an antitorque tail rotor configuration design that would come to be recognized worldwide as the helicopter.