Leonardo da Vinci’s invention often called the aerial screw was a helical flying-machine design.
Leonardo sketched the aerial screw around 1489–1490 in a manuscript now associated with the Codex Atlanticus. The drawing shows a large spiral sail or screw intended to rise by turning against the air. Its structure was inspired partly by the flight of the maple seed, whose spinning shape can slow its descent.
The design is frequently described as a helicopter predecessor, but it was not a working helicopter. Leonardo’s sketch lacks a practical engine, and the materials available in Renaissance Italy would probably have made the proposed machine too heavy. Modern helicopter rotors also generate lift through aerodynamic blades rather than a single linen-covered spiral.
The aerial screw remains important because it shows Leonardo applying geometry, mechanics, and observations of nature to human flight. It is distinct from his ornithopter, which imitates flapping bird wings, and from his parachute, which is intended to descend safely rather than climb.