Leonardo da Vinci sketched an aerial screw, a rotating device often compared with a modern helicopter rotor.
The design appears as a large helical sail or screw supported by a frame. Leonardo theorized that if the screw rotated rapidly enough, its surface might push against the air and lift the structure. The concept was an important attempt to apply the logic of a mechanical screw to vertical flight.
It was not a helicopter. The drawing does not show a practical engine, and the materials and human power available in the 15th century could not produce the necessary lift. The aerial screw also lacks the separate rotor, controls, and powered systems required by modern rotorcraft.
Because of its spiral form, the invention is often called a helicopter prototype, but “aerial screw” is the historically precise name. It demonstrates Leonardo’s imaginative approach to solving flight through physical principles rather than simply copying bird wings.