Leonardo da Vinci modeled an aircraft on a bird's flapping wings, called an ornithopter.
An ornithopter is a flying machine that produces thrust by flapping wings. Leonardo studied birds and bats extensively and designed several machines in which a human pilot would move wing mechanisms using arms, legs, or body weight.
His drawings explored wing shape, joints, control surfaces, and the relationship between lift and air movement. The designs were inventive, but a person cannot generate enough power with human muscles to sustain the kind of flapping flight Leonardo imagined. No Leonardo ornithopter is known to have flown.
The term applies to aircraft driven by flapping wings, whether powered by people, engines, or other mechanisms. It is therefore different from a glider, which relies on fixed wings, and from a helicopter, which uses rotating blades.