Leonardo da Vinci designed ornithopters, winged machines intended to fly by flapping their wings.
The word ornithopter comes from Greek roots meaning bird and wing. Leonardo studied bird anatomy, flight, wing movement, and air resistance while developing several flying-machine sketches. His designs generally assumed that a human pilot could operate wings through mechanical linkages powered by the arms or legs.
Leonardo’s ornithopters were not successful aircraft, because human muscle power is insufficient to drive wings of the required size and strength for sustained flight. They are also different from gliders, which generate lift with fixed wings, and from helicopters, which use rotating blades. Leonardo’s studies nonetheless contributed to the early history of flight concepts.