Helicopters

A helicopter is a type of rotorcraft in which lift and thrust are supplied by horizontally spinning rotors. This allows the helicopter to take off and land vertically, to hover, and to fly forward, backward and sideways. Most helicopters have one main rotor and a small tail rotor against the torque; others have two rotors in tandem, side by side, intermeshing or on one mast (coaxial).

The first practical helicopter, the Focke-Wulf Fw 61, flew in 1936, and the Sikorsky R-4 of 1942 was the first helicopter built in series. With the light turbine engine of the 1950s helicopters became powerful and reliable: today they are used for transport, rescue, police and medical flights, offshore work, fire fighting and as attack helicopters.