Leonardo da Vinci’s 1489 rotating spiral flying-machine concept is commonly called the aerial screw.
The design appears in one of his notebooks and resembles a large helical screw mounted on a frame. Leonardo proposed that rotating the screw could press against the air and lift the machine. The idea is frequently presented as an ancestor of the helicopter, although it was never built or tested by Leonardo.
The aerial screw would have faced major practical problems. The materials available in the fifteenth century were too heavy for the proposed machine, and human muscle could not provide enough power to rotate such a large rotor.
The design nevertheless anticipated the basic visual idea of a vertical-lift aircraft. Modern helicopters use powered rotors and aerodynamic blades rather than Leonardo’s continuous spiral surface.