Leonardo da Vinci’s ornithopter sketches were inspired primarily by birds’ wings. An ornithopter is an aircraft intended to fly by flapping wings, and Leonardo studied bird anatomy and flight to imagine how a human-powered machine might work.
His notebooks contain designs with large wings, pedals, levers and pulleys. Leonardo believed the pilot could operate the wings through mechanical linkages, although human muscles cannot provide enough sustained power for a full-size flapping aircraft. His studies included observations of how birds turn, balance and use air currents.
The sketches were exploratory rather than a single completed invention. Later ornithopters have flown using engines or remote control, but no Leonardo machine achieved powered flight. His bird studies nevertheless influenced the scientific study of aerodynamics and remain among the best-known examples of Renaissance flight research.