What is Leonardo da Vinci’s rotating flight-machine concept commonly called?

Leonardo da Vinci’s rotating flight-machine concept is commonly called the aerial screw.

Leonardo sketched the design around 1489. It featured a large helical surface made from reeds, linen, and wire, supported by a circular frame. His notes suggested that if the screw-shaped surface rotated rapidly, it might “screw” itself upward through the air. This makes the design an early conceptual relative of the helicopter, although it was not a helicopter in the modern engineering sense.

The aerial screw was never built and tested by Leonardo. Its proposed human-powered mechanism would not have supplied enough energy to lift the machine, and the design lacked many features needed for controlled flight, including a practical engine, rotor control, and a means of countering rotational torque.

The design is often mistakenly called Leonardo’s helicopter. That label is useful as a comparison, but “aerial screw” is the historically specific name used for the sketch and its helical lifting principle.