Leonardo da Vinci’s rotating-aircraft concept was the aerial screw.
Leonardo drew the aerial screw around 1489–1490. The design shows a large helical rotor made from reeds, linen, and a lightweight frame. Leonardo proposed that turning the screw could make it rise by forcing air downward, an idea that resembles the principle behind a helicopter rotor.
The sketch is famous because it anticipates rotary-wing aircraft, but it was not a working helicopter. The proposed structure was too large and heavy, and the human operators shown in reconstructions could not generate enough power to spin it effectively. Leonardo did not build a proven flying prototype from the drawing.
The design is sometimes casually called Leonardo’s helicopter, but “aerial screw” is the more historically specific name. Modern helicopters use powered rotors, aerodynamic blades, and control systems that Leonardo’s 15th-century concept lacked.