Leonardo da Vinci designed an ornithopter, an aircraft intended to fly by flapping wings powered by a pilot.
The word ornithopter combines Greek roots meaning bird and wing. Leonardo studied birds, bats, and the mechanics of flight, then produced many drawings exploring how a human might operate wing-like surfaces through pedals, levers, and other mechanisms.
His machines were not proven capable of carrying a person into sustained powered flight. Human muscles cannot provide the same power-to-weight ratio as the muscles of a flying bird, and Leonardo's designs also faced major problems involving weight, control, and structural strength.
The design is often confused with Leonardo's aerial screw. The aerial screw sought lift through rotating motion, while an ornithopter sought lift through repeated wing flapping.