Leonardo da Vinci’s human-powered, flapping-wing flying machine was an ornithopter.
Leonardo studied birds and bats because he believed their flight could reveal principles for human aviation. His ornithopter designs used wings that a person would move through pedals, levers, or other mechanical linkages. The word ornithopter comes from Greek roots meaning “bird” and “wing.”
Leonardo’s sketches were theoretical designs rather than working aircraft. Human muscles cannot provide enough sustained power to flap wings of the necessary size, so his machine could not fly as drawn. This is an important distinction from modern ornithopters, some of which are small radio-controlled aircraft.
The design is also often confused with Leonardo’s aerial screw, which resembles a helicopter rotor. The ornithopter depends on flapping wings, while the aerial screw depends on a rotating helical surface. Both belong to Leonardo’s late-fifteenth-century investigations into flight, but neither became a practical aircraft in his lifetime.