Leonardo da Vinci designed an aerial screw as a rotating-wing machine intended to lift itself into the air.
His drawing, dated to about 1489, shows a large helical surface made from linen stretched over a reed framework. Leonardo reasoned that if the screw rotated rapidly, its spiral surface might bite into the air and rise, much as a screw moves through a solid material.
The aerial screw is often called a helicopter predecessor, but it was not a practical helicopter. Leonardo had no lightweight engine capable of supplying the required power, and the proposed structure would have been difficult to control. The design therefore remained a study and was never flown by its creator.
Modern helicopters use powered rotors, aerodynamic blades, cyclic control, and anti-torque systems. Their operation depends on principles different from simply turning a large spiral sheet. Leonardo’s drawing is still historically significant because it identified vertical flight as a distinct engineering problem.