What spiral-shaped flying machine did Leonardo da Vinci design in 1489?

Leonardo da Vinci designed an aerial screw in 1489 as a spiral-shaped flying machine.

The aerial screw appears in Leonardo’s notebooks as a large helical structure made from reeds, linen, and wire. Leonardo reasoned that if the screw could rotate rapidly, its spiral surface might “screw” upward through the air, much as a conventional screw moves through a solid material.

The design is frequently described as an early helicopter concept, although it was never built or tested by Leonardo and could not have lifted its proposed structure with Renaissance machinery. Its importance lies in the underlying idea of vertical flight rather than in practical performance.

The aerial screw is also commonly called the “helicopter” in popular accounts, but that label can be misleading. Modern helicopters use powered rotors that generate lift through aerodynamic blades. Leonardo’s drawing predates powered rotorcraft by centuries and represents an imaginative mechanical hypothesis rather than a working aircraft.