One of Leonardo's most iconic images, the Aerial Screw (also known as the Helicopter) illustrates the ingenuity of da Vinci, and indicates (along with many other drawings!) his obsession with flying.

While it is often referred to as a helicopter, the premise of the lift to make it rise is more like archimedes screw than the rotors of a helicopter. This model uses one of the bevel gears he drew in his codices and creates a nice 2 to 1 increase in speed of the crankshaft, so the mast spins quickly, illustrating the manner in which this machine would have worked.