Leonardo da Vinci’s aerial screw used a helical rotor to imitate a screw moving through air.
Leonardo drew the aerial screw around 1489 and described a large spiral surface made from reed, linen, and wire. His idea was that the rotating helix would push against the air and lift the machine, much as a water screw advances through water. The drawing is one of his most famous studies of vertical flight.
The aerial screw was not a helicopter and was never shown to fly. It lacked an engine capable of providing the necessary sustained rotation, and its large fabric helix would have been difficult to control. Modern historians usually describe it as a conceptual precursor to helicopter flight rather than a functioning aircraft.
The machine is sometimes called Leonardo’s helicopter, but that label can be misleading. A helicopter uses powered rotors, aerodynamic blades, and controlled pitch, features not present in Leonardo’s proposal. The essential historical fact is the helical lifting concept, which links the drawing to later experiments with rotary-wing flight.