Leonardo da Vinci’s aerial screw, sketched around 1489, is commonly regarded as a precursor to the helicopter rotor. The drawing shows a helical linen surface wrapped around a wooden frame, with people turning a central shaft to make the device rise.
Leonardo reasoned that the rotating screw could push against the air in a way similar to how a screw moves through water. His machine was not a working helicopter, because the proposed human-powered mechanism could not generate enough lift with the materials and power available in the Renaissance.
The concept nevertheless anticipated a central feature of rotary-wing aircraft: rotating blades produce lift and allow vertical flight. Modern helicopter rotors use airfoil-shaped blades, engines, and carefully controlled pitch rather than a continuous fabric helix.
The aerial screw is sometimes described as the first helicopter, but that wording is misleading. It was a speculative design and was never built by Leonardo. Its historical value is as an early, visually clear study of vertical flight.