Leonardo da Vinci’s bird-inspired flapping-wing aircraft was an ornithopter.
An ornithopter is a machine that flies by moving wings in a birdlike or insectlike pattern. Leonardo filled notebooks with observations of birds and studies of wing motion, anatomy, balance, and air resistance. His proposed machines were intended to translate those observations into human flight.
Leonardo’s ornithopters were never successfully built or flown. Human muscles cannot supply enough power through a large flapping mechanism, and the materials available in Renaissance Italy were too heavy for the required structure. Later engineers usually found fixed wings, gliders, or powered propellers more practical.
The term is broader than Leonardo’s work: it includes any aircraft propelled by flapping wings, whether designed before or after him. Leonardo’s sketches remain historically important because they combine close natural observation with mechanical experimentation.