Leonardo da Vinci’s aerial screw used a rotating spiral sail to suggest vertical flight.
Leonardo drew the aerial screw around 1489. The design shows a large helical surface, supported by a circular frame, intended to rotate and push against the air. His notes compare the action to a screw moving through a solid material.
The drawing is often described as an early helicopter concept, but it was not a practical helicopter. The materials and human-powered mechanism available in Renaissance Europe could not generate enough lift to raise the complete structure.
The aerial screw is also commonly called the “helicopter” or “helical air screw” of Leonardo, although those labels are modern interpretations. Its historical importance lies in recognizing that a rotating airfoil might produce upward force, a principle later used in rotorcraft.