Leonardo da Vinci’s screw-shaped flying-machine concept is called the aerial screw.
Drawn around 1489, the aerial screw had a helical surface wrapped around a vertical framework. Leonardo theorized that if the screw rotated rapidly, its surface would bite into the air and lift the machine, much as a screw moves through a solid material. The design is often viewed as a distant conceptual predecessor of the helicopter.
The machine was not built and flown by Leonardo. Its proposed human-powered mechanism would not have produced enough lift, and the design lacked the aerodynamic understanding and lightweight engines needed for practical vertical flight.
The aerial screw should not be confused with a modern helicopter rotor. A helicopter’s blades generate lift through carefully shaped airfoils and powered rotation, while Leonardo’s drawing treated air more like a substance that a helical surface could penetrate.