Leonardo da Vinci called his rotating-linen flying machine the aerial screw.
Drawn around 1489, the aerial screw had a large helical surface made from linen stretched over a reed framework. Leonardo reasoned that if the spiral rotated rapidly enough, it might screw itself upward through the air, in much the same conceptual way that a screw moves through a solid material. The design is one of his best-known studies of vertical flight.
The aerial screw is frequently called a helicopter precursor, but it was not a working helicopter. Leonardo did not specify a sufficiently powerful engine, and the materials and mechanism shown could not realistically have lifted the full machine. Modern helicopters use powered rotors that generate lift through rotating airfoils, while Leonardo’s drawing presents a continuous spiral surface. Its importance lies in the early recognition that rotation could be used for vertical ascent. The design also influenced later popular images of Leonardo as a visionary inventor, even though it remained a theoretical machine.