Leonardo da Vinci's flying-machine design using a spiral rotor was the aerial screw.
Leonardo drew the aerial screw in the Codex Atlanticus, generally dated to around 1489. The design shows a large helical surface made from linen and reed, intended to rotate and push against the air. Leonardo compared its action with the way a screw advances through a solid material, although the proposed machine would not have had enough power to lift itself with the technology of his time.
The aerial screw is often described as an ancestor of the modern helicopter, but it was not a working helicopter and Leonardo did not build a successful flying prototype. Its importance lies in the early use of a rotating, screw-like rotor as a flight concept. The drawing also shows Leonardo thinking about materials, frame structure, and mechanical motion together.
The design is sometimes incorrectly called the first helicopter. Modern helicopters depend on powered rotors, refined aerodynamics, and control systems that were unavailable in Renaissance Europe. Leonardo's sketch was a remarkably early conceptual step, not a demonstrated aircraft.