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helicopter
Columbia Encyclopedia entry: helicopter
Helicopter, type of aircraft in which lift is obtained by means of one or more power-driven horizontal propellers called rotors. When the rotor of a helicopter turns it produces reaction torque which tends to make the craft spin also. On most helicopters a small rotor near the tail compensates for this torque. On twin-rotor craft the rotors spin in opposite directions, so their reactions cancel each other. The helicopter is propelled in a given direction by inclining the axis of the main rotor in that direction. The helicopter's speed is limited by the fact that if the blades rotate too fast they will produce compressibility effects on the blade moving forward and stall effects on the rearward–moving blade, at the same time. This method of flight was considered by Leonardo da Vinci, in the 16th cent., who described its possibilities but could not provide a propulsion system. Best known among its developers are the French inventor Louis Breguet and the engineers Igor Sikorsky of the United States and Juan de la Cierva of Spain. The helicopter has become very popular for short-distance transportation, because of its maneuverability and ability to land and take off in small areas; it has been adopted for a wide range of services, including air-sea rescue, fire fighting, traffic control, oil platform resupply, and business transportation. Helicopters have been widely adopted by the military since their first appearance during the Korean War. During the Vietnam War, they became the preferred platforms for transporting troops and evacuating wounded; in the Persian Gulf conflict helicopter gunships provided air cover for advancing tanks.

See A. Gessow and G. C. Myers, Aerodynamics of the Helicopter (1967); W. Johnson, Helicopter Theory (1984).

The Columbia Encyclopedia. Copyright © 2001-09 Columbia University Press. All rights reserved.

Wikipedia search results for: Helicopter
From Wikipedia, the free encyclopedia
A helicopter is a type of rotorcraft in which lift and thrust are supplied by one or more engine driven rotors. In contrast with fixed-wing aircraft, this allows the helicopter to take off and land vertically, to hover, and to fly forwards, backwards and laterally. These attributes allow helicopters to be used in congested or isolated areas where fixed-wing aircraft would not be able to take off or land. The capability to hover for extended periods of time, and to do so more efficiently than other forms of vertical takeoff and landing aircraft, allows helicopters to accomplish tasks that fixed-wing aircraft cannot perform. The word 'helicopter' is adapted...more »
Columbia Encyclopedia search results: helicopter
Results 1 - 10  of 34
  • heliport

    Heliport, airport designed exclusively for helicopter traffic.

  • Hiller, Stanley, Jr.

    Hiller, Stanley, Jr., 1924–2006, American aeronautical engineer and business executive, b. San Francisco. At 12 years old, he designed and produced gas-propelled toy cars, a business that led ...

  • autogiro

    Autogiro or gyroplane, type of aircraft supported in the air by a horizontally mounted airfoil similar to that of a helicopter but unpowered. Invented by the Spaniard Juan de la Cierva, it was...

  • Fountain Valley

    Fountain Valley, city (1990 pop. 53,691), Orange co., S Calif.; inc. 1957. Chiefly residential, Fountain Valley also has diverse manufactures, including apparel, computer equipment, semiconduc...

  • Hurst

  • Issy-les-Moulineaux

    Issy-les-Moulineaux, suburb SW of Paris (1990 pop. 46,734), Hauts-de-Seine dept., N central France. It is an industrial center where metals, aeronautical equipment, chemicals, cartridges, ciga...

  • Sikorsky, Igor Ivanovich

    Sikorsky, Igor Ivanovich, 1889–1972, American aeronautical engineer, b. Kiev, Russia. He immigrated to the United States in 1919 and was naturalized in 1928. Sikorsky built and flew the first ...

  • Stratford, town, United States

    Stratford, town (1990 pop. 49,389), Fairfield co., SW Conn., at the mouth of the Housatonic River on Long Island Sound; inc. 1639. Transportation equipment; helicopters; machinery; hardware it...

  • Yeovil

    Yeovil, town (1991 pop. 36,114), Somerset, SW England, on the Yeo River. It is a market town and a leather-making center. Glove making has been a local specialty since the 16th cent.; helicopt...

  • Brittan, Sir Leon

    Brittan, Sir Leon, 1939–, British politician. Educated at Cambridge, he was elected to Parliament as a Conservative in 1974. Under Margaret Thatcher he served as home secretary (1983–85) and s...

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