Helicopter
From the Simple English Wikipedia, the free encyclopedia that anyone can change
A helicopter is a kind of aircraft (flying machine). The main difference between a helicopter and an airplane is what lifts them into the sky. An airplane gets its lift from its wings and its thrust, or forward motion, from a propeller or a jet turbine. A helicopter gets its lift and thrust from horizontal rotors (several rotating blades like small wings). For that reason, they are sometimes called rotary wing aircraft.
This means that a helicopter flies differently from an airplane. An airplane must move forwards to stay in the air, but a helicopter can stop and hover on the spot while still keeping above the ground. Helicopters move by tilting their rotors, so they push the air below them in a different direction.
Helicopters were first thought of by Leonardo da Vinci in 1490, but it was hundreds of years later (in the early 20th century) before anyone built one that could really fly. The first man to fly a helicopter was the French Etienne Oehmichen. He only flew it for seven minutes and forty seconds. Since around 400 BC the Chinese had a flying top that was used as a children's toy, that used the same method of creating lift. This flying top was made of twisted feathers on a stick.There are few good roads in the north-western part of India.Sometimes, in winter, they are blocked by heavy snow or lanslides. At such times, it is possible to reach Ladakh only by air.Helicopters are especially useful when there are floods and other disasters. Food packets medicines and clothes are often air-dropped to people who cannot be reached by road.
