Leonardo da Vinci sketched an ornithopter, a machine intended to let humans fly by flapping wings.
The word ornithopter comes from Greek roots meaning bird and wing. Leonardo studied bird anatomy, wing motion, and the relationship between weight and lift while developing several flying-machine concepts. His drawings show a pilot connected to large wings through levers, pedals, and other mechanical controls.
Leonardo understood that a human pilot alone could not supply enough power for bird-sized flapping flight with Renaissance materials. Some designs were therefore more observational and experimental than practical aircraft proposals. His work still helped establish a systematic approach to studying flight.
An ornithopter differs from a glider, whose wings remain fixed while the aircraft descends or rides air currents. It also differs from a helicopter, which uses rotating blades. No Leonardo ornithopter is known to have flown successfully, but his notebooks remain influential in the history of biomimetic engineering.