What Leonardo da Vinci machine used a spiral sail to propose vertical flight?

Leonardo da Vinci’s aerial screw used a spiral sail to propose vertical flight.

Leonardo sketched the design around 1489 in his notebooks. The machine had a large helical surface made from reeds, linen, and wire. Leonardo reasoned that if the spiral were turned rapidly, it would screw upward through the air, much as a screw advances through wood.

The aerial screw is often called a helicopter prototype, but it was not a working helicopter. Its proposed lifting mechanism resembles the principle of a modern rotorcraft, while its shape resembles a screw or auger. No evidence shows that Leonardo built or tested a full-size version.

The design belongs to Leonardo’s wider study of flight, which also included gliders, parachutes, and flapping-wing machines. Modern helicopters use powered rotating blades and aerodynamic lift rather than a fabric-covered spiral sail.