Leonardo da Vinci’s helical machine concept is called the aerial screw.
Leonardo drew the aerial screw in a manuscript generally dated to about 1489. The design showed a large helical rotor made from reeds, linen, and wire, mounted on a platform. Leonardo reasoned that rotating the spiral surface could make it “screw” upward through the air, in a way that resembles a screw moving through a solid material.
The aerial screw is often described as a helicopter precursor, but it was not a functioning helicopter. The sketch did not provide a practical power source capable of rotating the large rotor fast enough, and its structure would have been difficult to control. Modern helicopters rely on powered rotors, aerodynamic blades, stability systems, and precise controls.
The drawing remains significant because it shows Leonardo thinking about vertical lift rather than only imitating birds. It is also commonly called the “helicopter” or “helicopter screw” in popular accounts, although “aerial screw” is the established name for the historical concept.