Leonardo da Vinci designed an aerial screw, a flying-machine concept with a large helical rotor.
The design appears in a manuscript dated to about 1489. It shows a broad spiral surface wrapped around a central mast. Leonardo reasoned that if the screw rotated quickly enough, its helical surface might bite into the air and lift the machine.
The aerial screw is often called a helicopter precursor, but it could not have flown as drawn. The proposed structure was too heavy, and human muscles could not provide enough power to rotate the large rotor. Modern helicopters use powered rotors with carefully shaped blades that generate lift through aerodynamic forces.
The concept remains historically important because it identifies vertical flight as a distinct engineering problem. Leonardo was not merely sketching wings; he was exploring rotary lift and the possibility of rising directly upward rather than gliding from a height.