Leonardo da Vinci’s aerial screw was a flying-machine concept designed to rise vertically using a helical rotor.
Leonardo drew the aerial screw in a notebook manuscript usually dated to about 1489. The machine resembles a large spiral sail or screw mounted on a frame. His idea was that the rotating surface would “screw” into the air and lift the structure, an approach that resembles the principle of a helicopter rotor.
The aerial screw was never built and flown by Leonardo, and the proposed human-powered mechanism could not supply the necessary energy. It is therefore better understood as an imaginative early study of vertical flight than as a working helicopter. The design is also distinct from the ornithopter, whose wings flap like a bird’s wings.