Leonardo da Vinci designed an ornithopter, a human-powered aircraft intended to fly with flapping wings.
The word ornithopter means “bird-wing,” and Leonardo studied birds extensively while developing his flying-machine ideas. His sketches show wing mechanisms operated by a pilot’s arms and legs, with frames inspired by the structure of bird wings and bats’ membranes.
Leonardo’s ornithopter was never successfully flown. Human muscles cannot supply the sustained power needed to flap wings large enough to lift a person, so the concept differs fundamentally from a glider or a powered airplane. His investigations still contributed to the history of aviation by treating flight as a problem of anatomy, mechanics, balance, and air resistance.