Leonardo da Vinci’s rotating-blade aircraft concept was called the aerial screw.
Leonardo sketched the aerial screw around 1489. The design shows a large helical rotor made from reeds, linen, and wire, mounted on a circular platform. His idea was that the rotating surface would “screw” itself upward through the air, much as a screw moves through a solid material.
The aerial screw is frequently described as an ancestor of the modern helicopter, but it was not a working helicopter. Leonardo’s drawing does not include an engine capable of turning the rotor fast enough, and the proposed structure would have been too heavy and aerodynamically inefficient. Its historical importance lies in identifying the basic concept of vertical lift from a rotating airfoil.
The aerial screw should also be distinguished from Leonardo’s flapping-wing ornithopter. The ornithopter imitates bird flight with reciprocating wings; the aerial screw uses continuous rotation. Modern helicopters became practical only after lightweight engines, strong materials, and refined rotor theory were developed.