Leonardo da Vinci sketched an aerial screw, a proposed lifting machine with a rotating spiral surface wrapped around a central shaft.
Leonardo drew the design around 1489, describing a framework covered with linen and stiffened with reeds. His idea was that the spiral surface would “screw” upward through the air if rotated rapidly. The concept is often called a helicopter predecessor, but it was not a practical helicopter and was never built by Leonardo.
Modern helicopters generate lift with rotating rotor blades that have carefully shaped airfoils and are powered by engines. Leonardo’s aerial screw instead resembled a large helical screw and lacked the power, materials, and aerodynamic understanding needed for flight.
The design is historically significant because it anticipated vertical-lift aircraft in concept. It should not be confused with Leonardo’s flapping-wing ornithopter, which sought to imitate bird flight rather than use a rotary screw.