Leonardo da Vinci designed an ornithopter as a bird-inspired flying machine powered by human muscle.
An ornithopter is an aircraft designed to fly by flapping wings, rather than using fixed wings or a rotating rotor. Leonardo studied birds extensively and sketched mechanisms in which a pilot could operate large wings with pedals, handles, or other linkages.
Leonardo’s concept was not a practical aircraft. Human muscles cannot provide enough sustained power to lift a person with flapping wings of the proposed kind. The design is nevertheless important in the history of aviation because it applied mechanical analysis to the problem of imitating bird flight.
An ornithopter is different from Leonardo’s aerial-screw design, which used a rotating helical surface and is often compared with a helicopter. Modern ornithopters exist mainly as small experimental or unmanned aircraft.