Leonardo da Vinci sketched an aerial screw as a flying-machine concept with a large helical screw.
Drawn around 1489, the device has a broad spiral surface mounted around a central mast. Leonardo proposed that the screw could push against air and rise if rotated rapidly. The idea is frequently described as an early ancestor of the helicopter, although the drawing does not show a practical engine or a complete control system.
The aerial screw was probably inspired partly by the whirling movement of a screw and by earlier Chinese flying toys. Leonardo’s notes demonstrate that he understood that air could provide resistance, but the materials and power sources available in his time could not make the machine fly.
Modern replicas are useful demonstrations of the concept, not proof that Leonardo built a working helicopter. The aerial screw remains one of his best-known studies of vertical flight.