Birds’ flight inspired Leonardo da Vinci’s ornithopter designs.
An ornithopter is a flying machine intended to stay airborne by flapping wings. Leonardo studied birds closely and filled his notebooks with observations about wing movement, balance, air currents, and the relationship between weight and lift. His proposed machines generally used human-powered mechanisms to imitate the motion of a bird’s wings.
Leonardo’s interest was analytical rather than purely artistic. He examined how birds change their wing position during upward and downward strokes and considered how a pilot might operate a wing-flapping machine. However, human muscles cannot provide enough sustained power for a practical bird-sized aircraft of the type he sketched.
Leonardo also drew designs with fixed or rotating wings, so not every flying-machine drawing is an ornithopter. The term specifically refers to flapping-wing flight. Modern ornithopters can fly as small experimental or model aircraft, but they are not evidence that Leonardo’s full-scale human-powered designs were built successfully.