What name did Leonardo da Vinci give his rotating flight-machine concept?

Leonardo da Vinci called his rotating flight-machine concept an aerial screw.

The design appears in a manuscript from around 1489 and shows a large helical surface wrapped around a vertical mast. Leonardo suggested that the screw could rise if its surface moved rapidly through the air, using an idea comparable to a screw advancing through wood or water.

The aerial screw is frequently described as a helicopter ancestor, but it was not a working helicopter. Leonardo did not provide a practical engine, lightweight materials, or a demonstrated method for producing enough lift. Its frame and sail-like surface would also have been difficult to control.

The concept is historically important because it recognized vertical lift as a separate problem from ordinary winged flight. Modern helicopters use powered rotors, which differ mechanically from Leonardo’s proposed helical rotor.