Leonardo da Vinci’s human-powered flying-machine concept based on flapping bird wings was an ornithopter.
An ornithopter is an aircraft designed to fly by flapping its wings rather than by using fixed wings or a propeller. Leonardo filled many notebooks with studies of birds, bats, wing motion, and the mechanics of flight.
His proposed machines used levers, pedals, and a wing framework to imitate the action of a bird. The designs were not practical because a human could not generate enough power to lift both the machine and its pilot through repeated flapping.
Leonardo’s work nevertheless helped distinguish several approaches to flight. His ornithopters differed from his aerial screw, which attempted vertical lift with a rotating helical surface, and from gliders, which rely on moving air over fixed wings.