Leonardo da Vinci’s aerial screw is a screw-shaped rotor concept intended to rise vertically through the air.
Leonardo drew the machine in a manuscript usually dated to about 1489. The design shows a large helical surface made from reeds, linen, and wire, with a platform and several people turning shafts to rotate it. Leonardo reasoned that the screw could “screw” into the air in a way similar to a screw moving through a solid material.
The aerial screw was a conceptual study rather than a completed aircraft. Its human-powered mechanism could not have produced enough lift, and the proposed structure would have been difficult to stabilize. Nevertheless, the drawing is frequently described as an early ancestor of the helicopter because it explores vertical lift with a rotating rotor.
Modern helicopters use powered rotors and aerodynamic blades, not a continuous spiral surface. The resemblance is therefore historical and conceptual, not evidence that Leonardo built a functioning helicopter.