What does Leonardo da Vinci’s aerial screw resemble in concept: a modern helicopter or a submarine?

Leonardo da Vinci’s aerial screw resembles a modern helicopter in concept because it was intended to rise through the air using a rotating helical surface. Leonardo drew the design around 1489, making it one of his best-known studies of vertical flight.

The machine consisted of a large spiral rotor made from reeds, linen, and wire, with a platform and supports below it. Leonardo reasoned that if the screw-shaped surface were turned rapidly, it could “screw” itself upward through the air, much as a screw moves through a solid material.

The aerial screw was not a functioning helicopter. It lacked a practical power source, and its materials and rotor arrangement could not generate enough useful lift. Modern helicopters use powered rotors with carefully shaped blades, aerodynamic control, and engines or electric motors.

Even so, the sketch anticipated the broad idea of rotor-borne flight. It should be described as a conceptual predecessor, not as the first working helicopter or a machine Leonardo actually built.