Leonardo da Vinci’s aerial screw used a large spiral blade to suggest vertical flight.
Drawn around 1489, the aerial screw consisted of a helical surface mounted around a central shaft. Leonardo reasoned that if the spiral were turned rapidly, it might screw itself upward through the air, much as a screw moves through a solid material. The design is often described as a conceptual ancestor of the helicopter.
The aerial screw was not a practical helicopter and was never tested as a working aircraft by Leonardo. The materials and power sources available in the Renaissance could not provide the thrust needed for vertical flight. Modern helicopters instead use powered rotors with carefully shaped blades, while Leonardo’s proposal relied on a continuous spiral surface. Its historical importance lies in recognizing that lift could be produced by rotary motion.