Helicopter accident

The use of a rotor for vertical flight has existed since 400 BC in the form of the bamboo-copter, an ancient Chinese toy.[1][2] The bamboo-copter is spun by rolling a stick attached to a rotor. The spinning creates lift, and the toy flies when released.[1] The philosopher Ge Hong's book the Baopuzi (Master Who Embraces Simplicity), written around 317, describes the apocryphal use of a possible rotor in aircraft: "Some have made flying carswith wood from the inner part of the jujube tree, using ox-leather (straps) fastened to returning blades so as to set the machine in motion."[3] Leonardo da Vinci designed a machine known as an "aerial screw" with a rotor based on a water screw. The Russian polymath Mikhail Lomonosov developed a rotor based on the Chinese toy. The French naturalist Christian de Launoy constructed his rotor out of turkey feathers.