Leonardo da Vinci’s bird-inspired flapping aircraft concept is an ornithopter.
An ornithopter is an aircraft intended to fly by moving wings up and down, rather than by using propellers or fixed wings. Leonardo studied birds and bats extensively and designed several human-powered flying machines based on their wing movements. His sketches included mechanisms for transferring motion from a pilot’s arms and legs to large wings.
Leonardo’s ornithopters were never successfully flown. Human muscles cannot provide enough sustained power for a machine of the required size, especially when the machine must also carry its own structure and pilot. Modern aircraft generally solve the lift-and-thrust problem with engines, propellers, or jet systems instead.
The word “ornithopter” comes from Greek roots meaning bird and wing. Leonardo’s work is historically important because it joined close observation of animal anatomy with mechanical design. His flight studies also included gliding surfaces and the aerial screw, which followed different ideas about how a machine might leave the ground.