Leonardo da Vinci’s bird-inspired human-flight design was an ornithopter.
An ornithopter is an aircraft intended to fly by flapping wings, rather than by using fixed wings or a rotating rotor. Leonardo filled his notebooks with studies of birds, bats, wing structure, air movement, and mechanisms that might allow a person to imitate animal flight. His proposed machines generally used large wings operated by the pilot’s arms and legs.
Leonardo understood that human muscles could not simply reproduce the power of a large bird. He therefore explored mechanical assistance, leverage, pedals, and stronger wing materials. Even so, his ornithopter concepts lacked an engine and did not provide a practical way for a person to generate enough sustained thrust.
The term is broader than Leonardo’s work and describes any flapping-wing aircraft, including later experimental machines. Leonardo’s designs should not be confused with his parachute or aerial screw. They are important because they combine close anatomical observation with mechanical experimentation, even though none achieved powered flight.