What name is given to Leonardo da Vinci’s spiral flying-machine design?

Leonardo da Vinci’s spiral flying-machine design is called the aerial screw.

Leonardo sketched the aerial screw around 1489, describing a framework with a helical surface intended to push against the air as it rotated. The drawing is often cited as an early conceptual ancestor of the helicopter, although it was not a working helicopter and could not have lifted itself with the materials and power available at the time.

The design used a large spiral sail or screw, commonly shown with a circular platform and a group of people turning a central mechanism. Leonardo appears to have reasoned that the spiral surface could “screw” upward through the air, just as a screw moves through a solid material.

It is sometimes incorrectly called a helicopter. A helicopter generates lift with powered rotating blades, while Leonardo’s aerial screw was a theoretical machine with a helical rotor concept. The idea remains one of the most recognizable inventions in his notebooks.