What was Leonardo da Vinci’s rotating helicopter-like design called?

Leonardo da Vinci’s rotating helicopter-like design was called the aerial screw.

Leonardo sketched the aerial screw around 1489. The design showed a large spiral structure made from reed, linen, and wire, with a central mast and a platform for people to operate it. Leonardo reasoned that the spiral surface could bite into the air and rise if turned rapidly enough.

The aerial screw was not a working helicopter. Its proposed size, materials, and human-powered mechanism would not have supplied enough lift for practical flight. Modern helicopters use powered rotors shaped as airfoils, a principle that differs substantially from Leonardo’s helical sheet.

The sketch is nevertheless important in the history of flight because it shows Leonardo thinking about vertical lift and rotary motion centuries before powered helicopters appeared. It is also commonly called a precursor to the helicopter, rather than the first helicopter itself.