What type of aircraft did Leonardo da Vinci study with his ornithopter designs?

Leonardo da Vinci studied flapping-wing aircraft in his ornithopter designs.

An ornithopter is an aircraft intended to fly by flapping wings, following the example of birds and bats. Leonardo investigated the subject through drawings and mechanical studies, especially in the late 15th and early 16th centuries. His sketches examined wing shapes, frames, joints, and ways a human pilot might generate movement.

Leonardo’s ornithopters were not powered flights. Human muscle alone cannot provide enough sustained power for a practical aircraft of the proposed size, and the machines lacked a suitable engine. Nevertheless, the studies show Leonardo trying to explain flight through observation, anatomy, mechanics, and experimentation.

An ornithopter differs from the aerial screw: the ornithopter depends on flapping wings, while the aerial screw depends on a rotating helical surface. Modern ornithopters exist as small experimental or model aircraft, but they are not descendants that turned Leonardo’s full-size plans into working machines.