Leonardo da Vinci called his screw-shaped air-lift concept an aerial screw.
Leonardo sketched the aerial screw around 1489. The design has a large helical surface supported by a light framework, with people turning shafts to make the structure rotate. His notes suggested that if the screw-shaped surface were made from suitable materials and spun rapidly, it might “screw” upward through the air.
The aerial screw was not a working helicopter. Its proposed human-powered mechanism lacked the energy and engineering efficiency needed to generate enough lift. Nevertheless, the concept is often described as an early ancestor of the helicopter because it anticipated rotary-wing flight.
Modern helicopters use powered rotors, not a continuous linen-covered helix. Leonardo’s sketch is best understood as a mechanical investigation of vertical flight, alongside his studies of gliders, parachutes, and flapping-wing machines.