Leonardo da Vinci’s aerial screw was a rotating aerial device often described as a precursor to the modern helicopter.
Leonardo drew the machine around 1489. Its design used a large helical surface made from linen, supported by a reed framework, with a central mast and a platform for operators. He reasoned that turning the screw rapidly might make it rise by forcing air downward.
The sketch is an important example of Leonardo applying the geometry of a screw to flight. However, the proposed machine would not have had enough power with the materials and human muscle available in the fifteenth century.
The aerial screw was not a functioning helicopter and had no engine, rotor controls, or modern fuselage. Its significance is conceptual: it anticipated rotary-wing flight by several centuries, while practical helicopters required lightweight engines and refined aerodynamic rotors.