Leonardo da Vinci’s four-person-powered helicopter concept is known as the aerial screw.
Leonardo drew the design around 1489. It featured a large helical rotor made from reeds, linen, and wire, mounted on a central structure. His notes suggested that four people would turn crank-like mechanisms to rotate the screw and force air downward, producing lift.
The concept is often described as an ancestor of the helicopter, but it could not have flown as drawn. The proposed materials and human power were insufficient for the required lift, and the design lacked the engine, controls, and lightweight structure needed for practical flight.
The aerial screw is also frequently called Leonardo’s “helicopter,” although that modern label can be misleading. Leonardo did not invent a functioning helicopter; he produced an influential early study of vertical flight using a rotating airfoil.