Leonardo da Vinci’s 1489 spiral machine designed to rise through the air is commonly called the aerial screw.
The sketch shows a helical sail wrapped around a central shaft and supported by a circular frame. Leonardo proposed that turning the shaft would force the surrounding air downward, causing the machine to move upward. The concept resembles the rotor principle later used by helicopters, although Leonardo’s design could not realistically lift itself with the materials and power sources available in the fifteenth century.
The aerial screw was a study of flight rather than a completed aircraft. Its linen-covered spiral was intended to act like a screw moving through a fluid, an analogy Leonardo extended from nautical and mechanical devices.
It is often called a helicopter in popular accounts, but “aerial screw” is the more historically precise name for Leonardo’s drawing. Modern helicopters use powered rotors with aerodynamic blades, not a single continuous spiral sail.