Leonardo da Vinci sketched an ornithopter as a human-powered flying machine with flapping wings.
An ornithopter is an aircraft designed to fly by wing movements resembling those of birds or bats. Leonardo studied bird flight and proposed mechanisms in which a pilot would move large wings through pedals, handles, or other mechanical controls.
Leonardo’s drawings were theoretical designs rather than working aircraft. Human muscles cannot provide enough sustained power to lift a person with flapping wings of the kind he imagined, so the machine was never successfully flown.
The design is often confused with Leonardo’s aerial screw, which used a helical rotor rather than flapping wings. Modern ornithopters have flown as small experimental models, but they are not direct practical descendants of Leonardo’s full-scale proposal.