Leonardo da Vinci sketched an ornithopter as an aircraft powered by flapping wings.
The word ornithopter comes from Greek roots meaning “bird” and “wing.” Leonardo’s surviving notebooks contain several studies of winged flight, including mechanisms intended to imitate the motion of birds and bats. His designs used a human pilot’s muscle power to drive the wings through pedals, levers, or other linkages.
Leonardo correctly observed that birds gain lift from air moving around their wings, but a human could not supply enough power to make a full-sized flapping aircraft fly. His ornithopter studies therefore remained designs rather than working aircraft. They are still important because they show his systematic investigation of anatomy, balance, lift, and mechanical transmission.
An ornithopter is different from a glider, whose wings remain fixed, and from an airplane, which uses fixed wings with forward motion supplied by a propeller or jet.