Leonardo da Vinci’s aerial-screw design was a rotating device intended to lift by driving air downward.
Drawn around 1489, the airscrew consists of a helical sail wrapped around a central shaft. Leonardo reasoned that if the screw rotated quickly enough, its spiral surface might bite into the air and raise the machine. The concept is frequently called a helicopter precursor, but it was not a working helicopter and lacked an engine capable of supplying the required power.
The design reflects Leonardo’s study of screws, mills, birds, and other mechanisms. Its central idea resembles the aerodynamic principle behind a propeller, although modern helicopter rotors generate lift through airfoils rather than a solid spiral sail.
The airscrew should therefore be treated as a conceptual machine, not as the first successful helicopter. Practical powered vertical flight required later developments in engines, lightweight structures, and rotor design.