Leonardo da Vinci's aerial screw was a concept for rising through the air with a large helical screw.
Leonardo drew the aerial screw in the 1480s, probably around 1489, in a manuscript now associated with the Codex Atlanticus. The design showed a linen-covered helical surface wrapped around a central mast. Leonardo reasoned that if the screw rotated quickly enough, its surface would press against the air and lift the machine.
The aerial screw is frequently called a helicopter precursor, but it was not a working helicopter. Leonardo did not provide a practical engine or a lightweight power system capable of turning the rotor. Modern helicopters use rotating airfoils and powered rotors, whereas the aerial screw relied on a solid helical surface. Its importance lies mainly in its early attempt to apply screw-like motion to vertical flight.