Leonardo da Vinci designed an aerial screw, a rotary-wing machine with a helical, screw-shaped rotor.
Leonardo sketched the concept in the 1480s. His drawing shows a large spiral surface made from reeds, linen, and wire, mounted around a central structure. He reasoned that if the spiral rotated quickly enough, it could “screw” upward through the air, much as a screw moves through a solid material or a ship’s propeller moves through water.
The aerial screw is often described as a distant ancestor of the helicopter, but it was not a functioning helicopter. Leonardo did not provide a practical engine powerful enough to spin the rotor, and the design would have faced major problems involving weight, control, and lift. Modern helicopters use powered rotors and aerodynamic blades rather than a continuous fabric spiral.
The idea remains important because it shows Leonardo thinking about vertical flight centuries before powered helicopters became possible. It is distinct from his flapping-wing ornithopter.