What Leonardo da Vinci flying-machine concept imitated a bird’s wing motion?

Leonardo da Vinci’s ornithopter concept imitated the flapping motion of a bird’s wings.

An ornithopter is an aircraft designed to fly by flapping wings rather than by fixed wings or a propeller. Leonardo studied birds extensively and produced several sketches of human-powered flying machines during the late fifteenth and early sixteenth centuries. Some designs placed a pilot in a frame who would operate wing mechanisms with the arms and legs.

Leonardo understood that a human pilot could not easily generate enough power to flap wings of the necessary size. His machines therefore remained theoretical or experimental proposals rather than successful aircraft. His observations of birds nevertheless contributed to early discussions of lift, balance, and wing structure.

An ornithopter differs from Leonardo’s glider-like designs, which used fixed wings and relied on aerodynamic lift. It also differs from the later helicopter concept, which used a rotating screw-shaped rotor. The defining feature of an ornithopter is flapping propulsion.