Leonardo da Vinci sketched an aerial screw as a proposed vertical-flight machine.
The design appears in Leonardo’s manuscripts from around 1489. It shows a large helical sail or screw wrapped around a central mast. Leonardo reasoned that, if the screw rotated rapidly enough, its surface might press against the air and lift the machine upward.
The aerial screw is often called an early helicopter concept, but it was not a working helicopter. Leonardo did not have a practical engine, lightweight structural materials, or a proven method for producing the required rotation. The design therefore remained a theoretical machine rather than a tested aircraft.
The idea is also different from Leonardo’s ornithopter studies. An ornithopter depends on flapping wings, whereas the aerial screw uses a rotating helical surface. Modern helicopters use powered rotating blades, making the aerial screw historically interesting but mechanically impractical in its original form.