Leonardo da Vinci’s 1485 screw-shaped flying-machine design is commonly called the aerial screw.
Leonardo sketched the device in the Codex Atlanticus. Its large helical surface was intended to push against air, much as a screw moves through a material. The drawing is one of his best-known studies of vertical flight.
The aerial screw was not a working helicopter. Leonardo did not build a powered prototype, and the materials and human power available in Renaissance Italy could not have lifted the proposed structure. Modern historians therefore describe it as an early conceptual study rather than a successful aircraft.
The design is often linked with helicopter history because its rotating principle resembles that of a rotor. However, modern helicopters use powered rotors, aerodynamic blades, and control systems that Leonardo’s sketch did not provide.