Leonardo da Vinci’s aerial screw proposed a rotating helical rotor to generate helicopter-like lift.
Leonardo drew the machine around 1489. The design shows a large spiral surface made from reeds, linen and a supporting frame. He reasoned that if the screw rotated rapidly, its surface would push against the air and raise the structure. The sketch is one of the earliest known concepts resembling a vertical-lift aircraft.
The aerial screw could not have flown as drawn because human power and the proposed materials would not provide enough thrust or rigidity. Modern helicopters use powered rotors with carefully shaped blades, not a continuous linen-covered spiral. Leonardo’s design is therefore a visionary aerodynamic concept rather than a functional aircraft.
It is sometimes called a proto-helicopter, but that label should not imply that Leonardo built or tested one.