Leonardo da Vinci’s flying-machine concept sketched as an “aerial screw” was the aerial screw. It used a large helical surface intended to rotate and lift the machine into the air.
Leonardo drew the design around 1489–1490, during his studies of flight and the movement of air. The drawing shows a wide spiral made from reeds, linen, and wire, with a central mast and a platform for operators. Leonardo appears to have imagined people turning the mechanism to generate upward force.
The aerial screw is often called an early helicopter or helicopter-like design, but it was not a working helicopter. Its proposed materials and human-powered mechanism could not provide enough power for practical flight. Modern helicopters rely on powered rotors and aerodynamic blades rather than a linen-covered spiral.
The design is historically important because it shows Leonardo reasoning about vertical lift centuries before powered rotorcraft became possible. It was one of several flying-machine ideas in his notebooks, alongside wing-flapping and gliding devices.