Leonardo da Vinci designed an aerial screw, a rotating machine intended to rise through the air.
The drawing, usually dated to around 1489, shows a large helical rotor made from reeds, linen, and wire. Leonardo proposed that the screw would push against the air in a way comparable to a screw moving through water. The concept is often treated as an important ancestor of the helicopter.
However, Leonardo’s machine was not a practical helicopter. Its proposed rotor was far too large and heavy for the available human power, and the design lacked the engine, control system, and lightweight materials needed for sustained flight. It is best understood as an imaginative aerodynamic experiment.
The term “aerial screw” is especially useful because it distinguishes Leonardo’s device from later helicopters. Helicopter development required advances in engines and rotor engineering during the 19th and 20th centuries, culminating in practical powered aircraft.