What is the usual English name for Leonardo da Vinci’s rotating aerial-screw aircraft concept?

Leonardo da Vinci’s rotating aerial-screw aircraft concept is usually called Leonardo’s helicopter.

Leonardo drew the aerial screw in the 1480s, probably around 1489. The machine had a large helical rotor made from reed, linen, and wire, mounted on a circular platform. His notes suggest that rotating the screw could make it rise by pressing against the air, an idea that resembles the principle of a helicopter rotor.

The machine was never built or flown by Leonardo. Its proposed power source was also inadequate for a full-size craft, and the design lacked several features needed for practical flight, including an effective way to control torque. Modern reconstructions have therefore treated it as an important conceptual experiment rather than a working helicopter.

The term “helicopter” is retrospective: the word comes from Greek roots meaning spiral and wing, while Leonardo described a screw-like aerial machine. His sketch is nevertheless one of the most famous early ideas for vertical flight.