Leonardo da Vinci’s aerial screw was a machine intended to rise by rotating a large, screw-shaped surface.
Leonardo drew the design in a manuscript usually dated to about 1489. The machine had a helical linen surface wrapped around a light framework. His notes suggest that rotating the screw would force air downward and lift the structure upward, an idea related to the principle behind a helicopter rotor.
The aerial screw could not have flown as drawn because its materials and human-powered mechanism could not produce enough lift. It also lacked a practical way to control and stabilize the craft. For that reason, historians generally describe it as an influential helicopter-like concept, not a working helicopter.
The design is frequently confused with Leonardo’s ornithopter, which imitated the flapping wings of birds. The aerial screw used rotary motion instead. Modern helicopters use powered rotors and aerodynamic blades, making them technically different even though Leonardo’s sketch is often cited as an early ancestor of the idea.