Leonardo da Vinci called his proposed helicopter-like flying machine with a helical rotor the aerial screw.
Leonardo sketched the aerial screw around 1489. The design used a large spiral rotor covered with linen, with a framework intended to rotate it and push against the air. Its shape resembles a giant screw moving through a solid material, which explains the name.
The aerial screw is often described as an early conceptual ancestor of the helicopter, but it was never built and tested by Leonardo. The drawing does not provide a practical engine or a proven method for producing enough rotational power. Modern helicopters rely on powered rotor blades, not a linen-covered spiral.
It is also frequently confused with Leonardo’s ornithopter, which imitated bird wings. The aerial screw used rotary lift instead, making it a separate flying-machine concept.