Leonardo da Vinci’s aerial screw was a vertical-flight machine designed around a large helical rotor.
Leonardo drew the aerial screw around 1489. The sketch shows a spiral sail or screw wrapped around a central mast, with people turning a platform beneath it. He reasoned that the rotating surface could “screw” upward through the air in a way similar to a screw moving through wood.
The aerial screw is often called a helicopter ancestor, but it was not a functioning helicopter. The proposed human-powered mechanism could not generate enough lift with the materials and power available in the fifteenth century. Modern helicopters use powered rotors with carefully shaped blades and sophisticated control systems. Leonardo’s importance lies in recognizing that rotary motion might produce vertical lift, a concept later explored by many engineers. The drawing is also commonly confused with an ornithopter, which would imitate the flapping motion of bird wings rather than use a rotating screw.