Leonardo da Vinci called his 1489 rotating device for lifting people into the air an aerial screw.
The design appears in the Codex Atlanticus and resembles a large helical screw mounted on a platform. Leonardo proposed that the screw's linen sail, reinforced with reeds, would rotate rapidly and push against the air. He wrote that the device should be made about 5 metres across, although the exact operating details are incomplete.
The aerial screw is frequently described as a helicopter ancestor, but it was not a functioning helicopter. Its mechanism lacked a practical power source, and human muscle could not have turned the rotor quickly enough to provide useful lift. Modern helicopters also rely on carefully shaped rotor blades and powered rotors rather than a continuous helical surface.
The idea nevertheless demonstrated Leonardo's interest in vertical flight. The sketch is one of several aviation concepts in which he tried to apply mechanical principles to observations of birds and air movement.