Leonardo da Vinci designed an ornithopter to imitate a bird’s flight.
An ornithopter is an aircraft intended to fly by flapping wings, rather than by using fixed wings or a rotating rotor. Leonardo studied birds extensively and filled notebooks with observations about wing movement, balance, air resistance, and the relationship between a bird’s wings and its tail.
His proposed human-powered machines generally placed a pilot inside a frame connected to large wings. The pilot would use pedals, levers, or other mechanisms to move them. Leonardo’s designs were ingenious, but a human could not supply enough power to achieve sustained flapping flight with the materials and technology available in the Renaissance.
The term ornithopter is broader than Leonardo’s work: modern experimental ornithopters can fly, but they use lightweight materials and powered mechanisms. Leonardo’s machines remained designs rather than successful aircraft.