Leonardo da Vinci studied an ornithopter as a bird-inspired flying-machine design.
An ornithopter is an aircraft intended to fly by flapping wings, rather than by using fixed wings or a propeller. Leonardo examined bird and bat anatomy, wing movement, balance, and the muscular effort required for flight.
His designs were not practical aircraft because human muscles cannot produce enough power for a person-sized flapping machine. Leonardo’s notebooks nevertheless contain important observations about lift, air resistance, and the mechanics of flight.
An ornithopter is not the same as a glider: a glider uses fixed wings and gains lift by moving through the air. Leonardo also explored a separate aerial screw design, which is often described as an early helicopter concept. Neither design was built as a working aircraft during his lifetime.