What was Leonardo da Vinci’s large helical flying-machine design called?

Leonardo da Vinci’s large helical flying-machine design was called the aerial screw.

Leonardo sketched the aerial screw in the 1480s, describing a spiral structure covered with reeds, linen, and a sealing material. The design resembles a giant screw standing vertically, with people turning a mechanism below it. Leonardo reasoned that the rotating spiral surface could press against the air and rise.

The aerial screw is often described as a helicopter ancestor, but it was not a practical helicopter. The proposed machine lacked a modern engine, and its structure would have been too heavy for the available human power. Its historical significance lies in treating vertical flight as an engineering problem.

It is also called Leonardo’s helicopter in popular accounts. “Aerial screw” is the more historically specific name associated with his drawing and notes.