Leonardo da Vinci’s spiral-rotor flying-machine design is called the aerial screw.
Leonardo drew the concept around 1489–1490 in his notebooks. It showed a large helical surface made from linen and reeds, intended to rotate around a central shaft and rise through the air. The design is often described as an early conceptual ancestor of the modern helicopter, although it could not have lifted itself with the materials and power available in Renaissance Italy.
The aerial screw was not a built, working aircraft. Leonardo’s drawing communicates a mechanical idea rather than a tested prototype, and the proposed rotor would have required a powerful engine that did not exist in his time. This is why historians usually call it a design or concept, not the first helicopter.
It is sometimes confused with Leonardo’s ornithopter, which copied the flapping motion of birds. The aerial screw instead relied on a rotating helical surface, making it one of Leonardo’s clearest studies of vertical flight.