Leonardo da Vinci designed an aerial screw with a large helical rotor as a proposed flying machine.
The drawing dates from around 1489 and appears in the Codex Atlanticus. Leonardo imagined a linen-covered helical surface, reinforced with reeds, that would push against the air when turned. His notes compare the action to a screw moving through a solid material, leading to the modern name “aerial screw.”
The concept resembles a helicopter rotor, but it was not a helicopter in the modern engineering sense. Leonardo did not provide a practical engine, a complete control system, or a reliable way to generate enough power for sustained flight. Human muscle alone would not have been sufficient to lift the proposed structure.
The aerial screw is historically important because it shows Leonardo thinking about vertical lift rather than relying only on wings. It was a speculative machine, not a documented working invention, and later helicopter technology required major advances in engines, materials, and aerodynamics.