Leonardo da Vinci’s bird-inspired human-powered flying-machine concept is an ornithopter.
An ornithopter is an aircraft intended to fly by flapping wings, rather than by using fixed wings or a conventional propeller. Leonardo studied birds, bats, and the mechanics of flight extensively, producing drawings of wings, frames, and control systems. His designs often placed a pilot inside a machine who would operate wing mechanisms with the arms, legs, or both.
Leonardo understood that human muscles alone were unlikely to provide enough power for a large flapping aircraft. His notebooks nevertheless contain detailed investigations of weight, balance, air movement, and wing structure. These studies helped establish an engineering approach to flight even though none of his ornithopter designs is known to have flown.
The word ornithopter comes from Greek roots meaning “bird” and “wing.” Modern ornithopters, including small radio-controlled models, have demonstrated flapping flight, but they do not make Leonardo’s Renaissance machine a successful powered aircraft.