What type of aircraft did Leonardo da Vinci design by studying bird flight?

Leonardo da Vinci designed an ornithopter, an aircraft intended to fly by flapping wings like a bird.

Leonardo studied birds, bats, and the movement of wings in several notebooks. His sketches explored wing shapes, frames, pedals, cables, and mechanisms that could transfer human muscle power into a flapping motion. The designs were attempts to understand flight mechanically rather than simply imitate a bird’s appearance.

An ornithopter differs from an airplane, whose fixed wings generate lift as the aircraft moves forward, and from a helicopter, whose rotor spins continuously. Leonardo’s human-powered concepts were not successful because a person cannot supply enough power for a machine of useful size using the proposed mechanisms.

Leonardo also considered gliding and screw-based flight. His work on ornithopters nevertheless influenced later discussions of aviation by treating flight as an engineering problem involving lift, drag, balance, and propulsion.