Leonardo da Vinci’s aerial screw used a rotating screw-like blade to propose vertical flight.
Leonardo sketched the device around 1489. The drawing shows a large helical surface supported by a framework. His notes suggest that if the screw-shaped surface rotated rapidly, it might rise by pressing against the air, an idea based partly on the behavior of a screw moving through a solid medium.
The aerial screw was not a practical helicopter and was never demonstrated as a working flying machine in Renaissance Italy. The materials and human power available to Leonardo would not have produced enough lift for the heavy frame. Modern helicopters instead use powered rotor blades designed with carefully controlled airfoils.
The concept is historically important because it recognized that vertical lift could be linked to rotation. It is often called a precursor to the helicopter, but that description should not imply that Leonardo built a helicopter or solved powered vertical flight.