What rotating machine did Leonardo da Vinci design to lift itself into the air?

Leonardo da Vinci designed an aerial screw as a theoretical machine intended to lift itself into the air.

His drawing, usually dated to around 1489, shows a helical sail wrapped around a central shaft. Leonardo proposed that the rotating structure could “screw” upward through the air, much as a screw moves through a solid material. The concept is one of the best-known precursors to the helicopter.

The aerial screw was not a working helicopter. Leonardo did not have a sufficiently light engine or a practical method for producing the required continuous rotation. The machine would also have needed a much lighter structure and better aerodynamic understanding to become airborne.

Modern historians distinguish the aerial screw from Leonardo's bird-like ornithopter studies. The aerial screw relies on rotary lift, while an ornithopter depends on flapping wings. Both belong to Leonardo's broader investigations into human flight, but they use different principles.