Leonardo da Vinci sketched an aerial screw as a proposed rotating aircraft centuries before modern helicopters.
The aerial screw appears in a drawing from around 1489. Its design uses a large helical surface, or screw, intended to push against the air and lift the machine upward when rotated. Leonardo compared the principle to a screw moving through a solid material, adapting a familiar mechanical idea to flight.
The machine was not a practical helicopter in the modern sense. It lacked a suitable lightweight engine and an efficient rotor system, and the proposed structure was too heavy for human-powered flight. Its significance lies in the early recognition that rotation could generate vertical lift.
The aerial screw is often called a helicopter precursor, but it should not be described as a functioning helicopter. Modern helicopters use powered rotors, aerodynamic blades, and control systems that Leonardo’s sketch did not provide.