What was Leonardo da Vinci’s rotating-wing design, sketched in 1489, called?

Leonardo da Vinci’s rotating-wing design, sketched in 1489, was called the aerial screw.

Leonardo drew the device in the Codex Atlanticus, probably around 1489. Its large helical surface was intended to rotate and lift the machine, much as a screw moves through a solid material. The design is often described as a conceptual ancestor of the modern helicopter, although it was not a working helicopter and Leonardo did not build a full-scale flying version.

The aerial screw relied on linen cloth stretched over a reed or cane framework. Leonardo’s notes suggested that the rotating structure might compress air beneath it. Modern aerodynamics shows that the drawing lacks several features needed for practical flight, including an effective powered rotor and a way to control torque.

It is commonly confused with Leonardo’s ornithopter, which used flapping wings. The aerial screw instead proposed rotary lift, making it one of the most recognizable early ideas related to vertical flight.