Leonardo da Vinci sketched an aerial screw as a precursor to the helicopter.
The drawing appears in a manuscript dated around 1489 and shows a large helical sail wrapped around a central mast. Leonardo reasoned that if the screw were rotated rapidly, its surface might “screw” upward through the air. The idea translated the behavior of a screw in a solid material into a proposed machine for flight.
The aerial screw was not a working helicopter. Leonardo had no engine light or powerful enough to spin such a large structure, and the design did not solve the modern helicopter’s problems of lift, stability, and control.
Its historical importance lies in the idea of vertical lift. Later helicopter development required lightweight engines, rotor blades, and control systems. The aerial screw is therefore best described as a conceptual ancestor of rotary-wing aircraft, not as the first helicopter itself.