Leonardo da Vinci sketched an ornithopter as a human-powered aircraft with flapping wings.
The word ornithopter comes from Greek roots meaning “bird” and “wing.” Leonardo studied birds closely and tried to translate their wing movements into a machine. His surviving notebooks show several winged designs, including mechanisms intended to transfer a pilot’s leg and arm power to large wings.
Leonardo’s ornithopter was never successfully built or flown. Human muscles cannot supply enough continuous power for a practical flapping aircraft of the size he imagined. This is an important distinction: Leonardo produced detailed engineering studies, but most of his famous flying machines remained designs rather than working aircraft.
An ornithopter differs from a glider, which has fixed wings, and from a helicopter, which uses rotating blades. Modern ornithopters are usually small experimental or radio-controlled machines, although some have carried people in carefully controlled tests.