Leonardo da Vinci sketched the aerial screw as an early helicopter concept.
The aerial screw appears in Leonardo’s notes from about 1489. Its design used a large helical sail or screw, supported by a frame, which Leonardo believed could rise if rotated quickly enough. The idea was inspired partly by the motion of a screw through a solid material and by Leonardo’s studies of air as a fluid.
The machine was not a helicopter in the modern engineering sense. It had no practical engine, and the proposed human-powered mechanism could not generate enough lift to raise the large structure. The sketch is therefore best described as a conceptual ancestor of rotary-wing aircraft rather than a working aircraft.
The aerial screw is often called a “helicopter” in popular summaries, but that label can hide the historical difference between Leonardo’s rotating canopy and a modern helicopter’s powered rotor. Its importance lies in identifying vertical lift as a separate aviation problem centuries before powered flight became possible.