What Leonardo da Vinci machine imitated a bird’s flapping wings?

Leonardo da Vinci’s ornithopter was a flying-machine concept that imitated a bird’s flapping wings.

Leonardo studied birds and designed several mechanisms in which a human operator would move wings through mechanical linkages. His notebooks include wing studies and diagrams of machines intended to reproduce powered flight by muscular action.

The ornithopter was not a successful aircraft. A human could not supply enough power through the proposed arrangement to lift the machine and pilot. Leonardo’s work nevertheless helped connect close observation of animal motion with engineering design.

An ornithopter differs from the aerial screw, which used a rotating helical surface, and from a glider, which depends on lift from fixed wings. Modern ornithopters do exist, especially as small experimental aircraft and models, but Leonardo’s large human-powered version remained a design rather than a working invention.