Leonardo da Vinci’s ornithopter was a proposed aircraft intended to fly by flapping wings like a bird.
Leonardo studied birds, bats and the mechanics of flight throughout his notebooks. His ornithopter designs used wings connected to levers, pedals or other mechanisms so that a pilot could generate motion by moving the machine’s controls. He understood that wings had to interact with air, and he carefully examined lift, balance and wing structure.
The designs were not proven practical aircraft. Human muscles cannot usually provide enough sustained power to flap a machine of the required size, and Leonardo lacked a lightweight engine. His work nevertheless contributed important observations about anatomy, aerodynamics and mechanical motion.
An ornithopter is different from a glider, which relies on fixed wings, and from Leonardo’s aerial screw, which proposed rotary lift rather than flapping wings.