What animal-inspired machine did Leonardo da Vinci study for powered flight?

Leonardo da Vinci studied an ornithopter, an animal-inspired machine for powered flight.

An ornithopter is a machine intended to fly by flapping wings, usually in imitation of birds or bats. Leonardo filled notebooks with observations of bird anatomy, wing motion, balance, and airflow. His proposed flying machines used human or mechanical power to move wings, reflecting his belief that careful study of nature could guide engineering.

Leonardo’s ornithopter concepts were never successfully flown. Human muscles do not provide enough power for a person-sized flapping aircraft of the type he imagined, and his designs lacked the lightweight engines and aerodynamic knowledge later used in aviation. He also investigated gliding and screw-powered flight, so not every Leonardo aircraft sketch is an ornithopter.

The word comes from Greek roots meaning “bird” and “wing.” Modern ornithopters exist as experimental aircraft and small radio-controlled models, but they are not direct proof that Leonardo’s Renaissance designs worked. His lasting contribution was the systematic study of flight mechanics and animal movement.