Leonardo da Vinci’s spiral flying-machine concept in the Codex Atlanticus was the aerial screw.
Leonardo’s aerial screw is usually dated to around 1489. The drawing shows a large helical surface wrapped around a central mast, with a platform and people turning a mechanism below it. Leonardo reasoned that the screw might rise by “screwing” into the air, in a way loosely analogous to a screw moving through a solid material.
The design was not tested successfully in Leonardo’s lifetime and could not have lifted its proposed crew with the materials and power available then. It is often described as a distant conceptual ancestor of the helicopter, although modern helicopters use rotating airfoils, engines, and carefully engineered control systems.
The aerial screw is sometimes mistakenly called Leonardo’s helicopter. “Helicopter” is the later aircraft category; “aerial screw” is the name generally given to Leonardo’s Renaissance concept.