Leonardo da Vinci studied vertical lift using a rotating screw-like rotor.
His aerial-screw design featured a large helical surface intended to push against the air as it rotated. Leonardo reasoned that the motion could make the device rise vertically, an idea that anticipates the basic lift direction of a helicopter.
The concept was not a working helicopter. The design lacked a practical engine and the materials and power available in Leonardo’s time could not have provided the required sustained rotation. It is therefore best understood as a theoretical flying-machine study.
The aerial screw is often called a helicopter precursor, but it should not be confused with Leonardo’s separate flapping-wing ornithopter drawings. The screw sought lift from rotation, while the ornithopter sought lift from wing flapping.