Leonardo da Vinci’s rotating aerial machine powered by a large helical screw is commonly called the aerial screw.
Leonardo drew the concept in a notebook dated approximately 1489. The machine has a large spiral rotor made from reeds, linen, and wire, supported by a circular platform. His notes suggest that rotating the screw could make it rise by pressing against the air, an idea that resembles the action of a modern helicopter rotor.
The aerial screw is often described as a helicopter precursor, but it was not a practical helicopter. Leonardo’s drawing does not show a usable engine, and the materials and human power available in the fifteenth century could not have provided enough lift for the heavy structure. Modern helicopters also need controlled rotor blades, a power source, and a way to counter torque.
The design remains important because it shows Leonardo reasoning about vertical flight. It should not be confused with his separate flapping-wing ornithopter, which attempted to imitate bird flight rather than screw-driven lift.