Leonardo da Vinci called his rotating aircraft concept with a helical sail the aerial screw.
Leonardo sketched the aerial screw around 1489 in the Codex Atlanticus. Its design used a large helical surface, probably covered with linen stiffened with starch, that was intended to rotate and push against the air. The drawing is often described as an early helicopter or vertical-flight concept.
The aerial screw was not a working aircraft. Leonardo did not provide a practical engine, and the proposed structure would have been too heavy for the available materials and human muscle power. Modern reconstructions therefore demonstrate the idea rather than reproduce a flyable machine.
The design is sometimes called a helicopter, but “aerial screw” is Leonardo’s associated concept name. It is also distinct from his ornithopter, which sought lift through flapping wings rather than a rotating helical surface.