Leonardo da Vinci called his 1489 machine with a rotating helical screw an aerial screw.
The aerial screw is one of Leonardo’s best-known studies of flight. His drawing shows a large helical surface wrapped around a central mast. Leonardo reasoned that if the screw were rotated rapidly, its surface might press against the air and lift the machine, an idea often compared with the principle of a helicopter rotor.
The sketch does not show a practical engine, control system, or proven method for supplying enough power. Human muscles alone could not have driven a full-sized version effectively. For that reason, the aerial screw is generally treated as a conceptual aircraft design rather than a successful helicopter.
It is sometimes called a helicopter because of its appearance and proposed vertical lift. However, the modern helicopter uses powered rotors that generate lift through aerodynamic blades, not a fabric-covered spiral screw. Leonardo’s drawing remains an important early study of vertical flight.