Leonardo da Vinci designed ornithopters, flying machines intended to rise through the flapping of wings.
Leonardo studied birds and bats extensively, recording observations about wing structure, airflow, balance, and the relationship between weight and lift. His flying-machine sketches show human-powered mechanisms with wings shaped to imitate those of birds. The term “ornithopter” comes from Greek words meaning bird and wing.
Leonardo recognized that human muscles could not easily generate enough power for a bird-sized flapping machine. Some of his later designs therefore placed the operator inside a frame and used pedals, levers, and pulleys to move the wings. None is known to have flown successfully.
An ornithopter differs from a glider, which stays aloft through forward motion and fixed wings. It also differs from a helicopter, which uses rotating blades. Leonardo’s work was important as an investigation of flight, even though his machines remained theoretical.