Leonardo da Vinci’s bird-inspired flight machine was an ornithopter, a craft designed to fly by flapping wings.
Leonardo studied birds, bats, and the mechanics of their wings while developing several human-powered flying-machine sketches. An ornithopter attempts to generate lift and thrust through repeated wing movement rather than through a fixed wing or a rotating rotor. His concepts included wings, frames, and control arrangements intended to translate human effort into flapping motion.
Leonardo’s ornithopters were not demonstrated as successful human-carrying aircraft. Human muscles cannot easily supply the power needed to sustain flapping flight at that scale, and the designs also faced problems involving weight, control, and wing strength. Nevertheless, his studies helped connect observation of animal flight with mechanical design.
An ornithopter is distinct from Leonardo’s helical rotating-aircraft concept, commonly called an aerial screw. The ornithopter flaps wings; the aerial screw relies on a rotating helical surface. Both belong to Leonardo’s investigations of flight, but they use different principles.