Leonardo da Vinci’s aerial screw was a flying-machine concept with a large helical rotor.
Leonardo sketched the design around 1489. It resembles a huge vertical screw, with a linen-covered frame wound around a central mast. His notes suggested that the rotating surface could compress air and lift the machine, an idea that visually anticipates the helicopter rotor.
The aerial screw was not a functioning helicopter. Leonardo had no lightweight engine capable of supplying the sustained power needed to rotate such a large device, and the design’s materials and aerodynamics were inadequate for practical flight. Human-powered versions would also have lacked enough power.
The concept is nevertheless historically significant because it proposed vertical lift rather than relying on wings and forward motion. Modern helicopters use rotating blades, but their engineering is fundamentally different from Leonardo’s helical construction.