Leonardo da Vinci designed an aerial screw as a proposed machine for lifting from the ground.
His drawing, made around 1489, shows a large helical structure mounted on a platform. Leonardo reasoned that if the screw rotated quickly enough, its surface could push against the air and raise the machine. The concept is widely regarded as an early precursor to the helicopter, though it was never built or flown by Leonardo.
The aerial screw should not be confused with a working helicopter. Leonardo lacked a lightweight engine and a practical method for producing the necessary continuous rotation. Modern helicopters use powered rotors and aerodynamic lift rather than a linen-covered spiral screw. The sketch nevertheless shows Leonardo thinking about vertical flight more than four centuries before powered helicopters became practical.