Leonardo da Vinci designed an ornithopter, a flying machine intended to rise through the flapping of wings.
Leonardo studied birds, bats, and the mechanics of flight in notebooks dating mainly from the late fifteenth and early sixteenth centuries. His proposed machine used wings that a human pilot would operate, reflecting his belief that a person might imitate the muscular action of a bird.
An ornithopter is not the same as a glider or a helicopter. A glider relies on aerodynamic lift while moving forward, and a helicopter uses rotating blades. Leonardo’s designs were important as investigations of flight, but they were not practical aircraft because human muscles cannot generate enough sustained power for a full-sized flapping machine.
The designs nevertheless anticipated later aeronautical ideas, especially the importance of wing shape, weight, balance, and air resistance. Leonardo’s flying-machine studies also included parachute, screw, and gliding concepts.