Leonardo da Vinci designed an ornithopter, an aircraft intended to fly by flapping wings.
Leonardo studied birds extensively and filled his notebooks with observations about their wings, tails, balance, and muscles. His proposed ornithopters used human or mechanical power to imitate flapping flight rather than relying on engines or propellers.
Leonardo’s designs were not practical aircraft because a human operator could not generate enough power for sustained flight. They nevertheless helped establish a long-running tradition of biomimetic aviation. Leonardo also explored gliders and a helical aerial screw, but those were different concepts.
The word ornithopter comes from Greek roots meaning “bird” and “wing.” Modern ornithopters can fly as radio-controlled models, although they remain specialized machines rather than common passenger aircraft.