Leonardo da Vinci designed ornithopters, machines intended to fly by flapping wings like birds.
Leonardo studied bird anatomy and flight in detail, especially the relationship between wing movement, air, and balance. His ornithopter sketches show human-powered machines with wings that would be moved by mechanical linkages. Some versions used the pilot’s arms or legs to operate the mechanism.
The designs were never practical aircraft. A human could not generate enough power to flap wings of the required size, and the machines lacked a lightweight engine. Leonardo eventually explored other flight concepts, including gliding and the aerial screw.
An ornithopter is defined by flapping-wing propulsion, not by its appearance alone. That technical definition separates Leonardo’s bird-inspired machines from his rotorcraft and fixed-wing experiments.