Leonardo da Vinci sketched an aerial screw as a proposed flying device with a helical rotor.
Leonardo recorded the design around 1489 in his manuscripts. It shows a large spiral structure made from reeds, covered with linen and strengthened with wire. His notes suggest that the rotating surface could screw upward through the air, an idea resembling a giant airborne screw.
The design is often called a helicopter prototype, but it was not a functioning helicopter. Leonardo did not have a practical engine or a demonstrated method for producing enough sustained power. The drawing is therefore best understood as a theoretical experiment in aerodynamics, not evidence that he built a working aircraft.
The aerial screw is also distinct from Leonardo’s ornithopter, which used flapping wings. Modern helicopters use powered rotors and aerodynamic lift, whereas the aerial screw depended on a very different proposed mechanism.