About Helicopters

Abstract

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, backward 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 efficiently hover for extended periods of time allows a helicopter to accomplish tasks that fixed-wing aircraft and other forms of vertical takeoff and landing aircraft cannot perform. The word 'helicopter' is adapted from the French hélicoptère, coined by Gustave de Ponton d'Amecourt in 1861, which originates from the Greek helix/helik = "twisted, curved" and pteron = "wing". Helicopters were developed and built during the first half-century of flight, with the Focke-Wulf Fw 61 being the first operational helicopter in 1936. Some helicopters reached limited production, but it was not until 1942 that a helicopter designed by Igor Sikorsky reached full-scale production, with 131 aircraft built. Though most earlier 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. The earliest references for vertical flight have come from China. Since around 400 BC, Chinese children have played with bamboo flying toys and the 4th-century AD Daoist book Baopuzi ("Master who Embraces Simplicity") reportedly describes some of the ideas inherent to rotary wing aircraft: 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 fastened to returning blades so as to set the machine in motion." It was not until the early 1480s when Leonardo da Vinci created a design for a machine that could be described as an "aerial screw" that any recorded advancement was made towards vertical flight. His notes suggested that he built small flying models, but there were no indications for any provision to stop the rotor from making the whole craft rotate. As scientific knowledge increased and became more accepted, men continued to pursue the idea of vertical flight. Many of these later models and machines would more closely resemble the ancient bamboo flying top with spinning wings, rather than Da Vinci's screw.