Leonardo da Vinci sketched an aerial screw as a spiral screw powered by human effort.
Usually dated to around 1489, the design appears in Leonardo’s manuscripts as a large helical surface wrapped around a central mast. Leonardo proposed that the screw might rise if its surface pushed against the air, an idea that resembles the operating principle of a modern helicopter rotor.
The machine was not a helicopter in the modern engineering sense. It had no engine, and the proposed human power would not have been sufficient to lift the structure. The drawing is therefore best understood as a study of aerial propulsion rather than a successfully tested aircraft.
The aerial screw is often called a helicopter precursor, but that description can cause confusion. A helicopter generates lift with rotating blades and controls its motion with an engine and rotor system. Leonardo’s broad spiral surface would have behaved differently. Nevertheless, the sketch is one of his clearest attempts to imagine vertical flight and is among the most famous pages associated with his studies of invention.