Toy helicopters have been around for centuries, and those made by air pioneer Sir George Cayley in the early 19th century are the most famous.
On 13 November 1907 a primitive helicopter with two sets of rotors lifted French mechanic Paul Cornu off the ground for 20 seconds.
The problem with pioneer helicopters was control. The key was to vary the pitch of the rotor blades.
In 1937 German designer Heinrich Focke built an aircraft with two huge variable pitch rotors instead of wings and achieved a controlled hover. Months later, German Anton Flettner built the first true helicopter.
Focke and Flettner’s machines had two rotors turning in opposite directions to prevent torque reaction. In 1939, Russian-born American Igor Sikorsky solved the problem by adding a tail rotor.
The Jesus nut that holds the main rotor to the shaft got its name because pilots said, “Oh Jesus, if that nut comes off…”.
The biggest helicopter was the Russian Mil Mi-12 Homer of 1968 which could lift 40,204 kg up to 2255 m.
The fastest helicopter is the Westland Lynx, which flew at 402 km/h on 6 August 1986.
The Boeing/Sikorsky RAH-66 Comanche unveiled in 1999 is the first helicopter using stealth technology. It is made of carbon-fiber and other composite materials, and the rotor hub is hidden.