Leonardo da Vinci’s wing-flapping aircraft concept is commonly called an ornithopter.
The term ornithopter refers to a machine that flies by flapping wings, following the basic motion of birds, bats, or insects. Leonardo studied this idea extensively through anatomical observations and mechanical sketches, especially during the late fifteenth and early sixteenth centuries.
His designs included wings, frames, pedals, and levers intended to transmit a pilot’s movement to the wings. They were important investigations of flight mechanics, but they could not overcome the limited power available from a human operator. No Leonardo ornithopter is known to have flown.
The concept should not be confused with the aerial screw, which sought vertical movement through a rotating helical surface. Leonardo also drew gliding and parachute-related ideas, but an ornithopter is specifically defined by flapping-wing propulsion.