One of Leonardo's most iconic images, the Aerial Screw (also known as the Helicopter) illustrates the ingenuity of da Vinci, and indicates his obsession with flying. While this idea may never have got off the ground, for some basic technical reasons, it gave us an insight into the different ways in which Leonardo considered the challenge of human powered flying, and defines him as an inventor well ahead of his time. 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. Kit features pieces that are drilled and pegged for strength, the canopy and support structure are removeable for experimenting, and lots of interesting information about how it works. Kit stands about 15" tall and 9" across.