Leonardo da Vinci’s rotating helical-blade helicopter concept was called the aerial screw.
Leonardo drew the aerial screw in a manuscript usually dated to around 1489. The design showed a large spiral-shaped rotor made from a reed framework covered with linen. Leonardo reasoned that the rotating screw could “screw” upward through the air, much as a threaded screw moves through a solid material.
The aerial screw was not a practical helicopter and was not built or tested by Leonardo. Its frame would have been too heavy, and the design lacked a suitable power source and modern rotor controls. Nevertheless, it is frequently cited as an important early idea in vertical flight.
The design is sometimes called a helicopter precursor, but it should not be confused with a working helicopter. Modern helicopters use powered rotors, aerodynamic blades, and control systems developed many centuries later. Leonardo’s drawing shows the value of conceptual engineering even when the technology needed to build the machine did not yet exist.