Leonardo da Vinci sketched an ornithopter, a flying device intended to rise by flapping winglike surfaces inspired by birds and bats. The word comes from Greek roots meaning “bird” and “wing.”
Leonardo studied bird flight, wing structure, air resistance, and the movement of feathers. His proposed machine placed a human pilot in a framework connected to large wings. The pilot would use mechanical levers and pedals to imitate the muscular action of a flying animal.
No Leonardo ornithopter was completed or shown to fly. Human muscles cannot provide enough sustained power to flap wings of the necessary size, which is why powered aircraft eventually relied on propellers or jet engines rather than direct imitation of bird flight.
The design remains important in the history of aviation because it treated flight as an engineering problem. Leonardo combined observation of nature with mechanisms, although his conclusions about how much lift and power a person could produce were limited by the technology of his era.