What kind of aircraft did Leonardo da Vinci study with flapping wings?

Leonardo da Vinci studied an ornithopter, an aircraft designed to fly with flapping wings.

Leonardo examined the anatomy and flight of birds and bats while developing machines that imitated their wing movements. His sketches included mechanisms intended to transmit a pilot’s muscular effort to large wings.

The word ornithopter comes from Greek roots meaning bird and wing. Unlike an airplane, which uses fixed wings, an ornithopter seeks lift and thrust through repeated wingbeats. Leonardo’s studies were influential as investigations, but his human-powered designs were not practical because human muscles could not provide enough sustained power.

Leonardo’s ornithopter work is sometimes confused with his aerial screw. The ornithopter depended on flapping wings, while the aerial screw depended on a rotating helical rotor. Neither design became a working aircraft during Leonardo’s lifetime.