Leonardo da Vinci designed an ornithopter, a bird-inspired aircraft intended to fly by flapping wings.
Leonardo studied birds extensively and filled notebooks with observations about wing movement, balance, air resistance, and gliding. His ornithopter designs generally placed a human pilot inside or beneath a large wing structure, with the pilot operating mechanisms intended to imitate a bird’s muscular wingbeats.
The designs were never demonstrated as successful human-powered aircraft. Human muscles cannot provide enough sustained power for a machine of the proposed size, although Leonardo’s aerodynamic observations were important early studies of flight.
An ornithopter is different from Leonardo’s famous aerial screw: the ornithopter uses flapping wings, while the aerial screw was a rotary-wing concept. The word comes from Greek roots meaning “bird” and “wing.”