Leonardo da Vinci's aerial screw was an aircraft concept with a large helical rotor above a central cabin.
Leonardo drew the design in the 1480s, probably around 1489. The machine used a spiral sail or screw made from reed, linen, and wire. His notes suggested that if the screw were turned rapidly, its helical surface might push against the air and lift the device.
The aerial screw was never built or flown by Leonardo. Its mechanism resembles the principle of a helicopter rotor, but the comparison has limits. A modern helicopter generates lift with rotating airfoils and an engine; Leonardo's concept depended on a large, fabric-covered helix and did not include a workable power system.
The sketch is famous because it anticipates vertical flight, not because it was a functioning helicopter. The term “aerial screw” is the standard English name used for the design. Later flying-machine experiments developed independently and relied on engines, propellers, or airfoils rather than Leonardo's proposed screw.