Leonardo da Vinci designed the aerial screw as a helical device intended to lift a machine into the air.
The drawing appears in a manuscript dated to around 1489. Leonardo proposed a large screw-shaped framework covered with reed, linen, and other lightweight materials. He reasoned that rotating the helix through the air could produce upward motion, an idea that resembles the principle behind a modern helicopter rotor.
The aerial screw was not a working helicopter. Leonardo’s design lacked a practical power source capable of turning the structure fast enough, and its heavy materials would have created major engineering problems. The design is therefore best understood as an early investigation of vertical flight rather than a completed aircraft.
Its appearance also shows Leonardo’s habit of exploring flight through several different approaches. He studied gliding surfaces, flapping wings, parachutes, and rotating mechanisms. The aerial screw is sometimes casually called a helicopter, but that modern name describes a later aircraft category, not Leonardo’s original machine.