Helicopter

A helicopter is an engine-driven rotorcraft (a type of aircraft) which uses rotating blades for lift, propulsion, thrust and steering. The word 'Helicopter' comes from the French word 'hélicoptère' which is derived from the Greek words 'helix/helik' (which means 'twisted / curved') and 'pteron' (which means 'wing'). As helicopters have engine driven rotors for propulsion, they have the following advantages over fixed-wing aircrafts:

• Helicopters can take off and land vertically.
• They can hover and fly in any direction (forwards, backwards and sidewards).

The first practically successful rotorcraft (the Autogiro) was built by the Spanish engineer Juan de la Cierva, in the year 1923. This vehicle used autorotation (Rotation of blades based on unpowered rotor which solely depended on the flow of air for lift and thrust). The mobility of the autogiro built by Juan de la Cierva was completely dependent on the air flow.

The first fully functional helicopter ever built is the Focke-Wulf Fw 61. It was built by Henrich Focke and Gerd Achgelis. It was first flown in the year 1936.

The forerunner of modern helicopters is the Vought-Sikorsky VS-300. It was designed by the Russian American Igor Sikorsky in the year 1939.

In 1951, an American aeronautical engineer Charles Kaman modified his Kaman K-225 helicopter with the turboshaft engine. This modified Kaman K-225 became the world's first gas turbine-powered helicopter. The introduction of turboshaft engines to helicopters enabled the creation of faster, larger, reliable and efficient helicopters.

Owing to their versatility in flight, helicopters have a wide variety of applications. They are used for traffic surveillance, transportation, news gathering, aerial photography, crop-spraying, tourism, searching and rescuing etc.

A Rescue Helicopter