What rotating-wing aircraft did Leonardo da Vinci sketch for vertical flight?

Leonardo da Vinci sketched an aerial screw as a concept for vertical flight.

The drawing, usually dated to around 1489, shows a large helical surface mounted on a frame. Leonardo reasoned that if the screw rotated quickly enough, its shape might push against the air and lift the machine. The idea resembles the principle later used by helicopter rotors, although its proposed structure and materials were very different.

The aerial screw was a study, not a demonstrated aircraft. Leonardo did not have a lightweight engine or a practical method for producing the required power. The machine also lacked the aerodynamic rotor design and control systems essential to modern helicopters.

The aerial screw is distinct from Leonardo’s wing-flapping ornithopter studies. The screw sought lift through rotation, whereas an ornithopter imitates the flapping motion of birds. That difference makes it one of Leonardo’s clearest early explorations of rotary flight.