Screw-Propelled Vehicle

Basic Information

To begin with, get your mind out of the gutter. We're not talking about that kind of screw. A screw-propelled vehicle is one that utilizes rotating cylinders with helical ridges spiraling along their sides which grip the surface on which the vehicle rests and push it along. It works similar in principle to the Archimedes screw, except that instead of remaining stationary while it conveys material, in this case the material stays where it is and the mechanism attached to the screw moves along.

This, naturally, results in a highly-specialized vehicle. It won't work very well on a hard surface like a concrete road; but it performs quite well on surfaces like snow, or mud and swamp. Such machines typically have a set of two cylinders, with the helical flanges spiraling and rotating in opposite directions so as to counterbalance each other. The first machines with this design were intended as agricultural machines, with the idea that the spiral blades would double as a means of propulsion and a tiller to break up the soil. The first vehicle actually built, patented in 1907, was intended to haul lumber across snow and ice.

During World War II, the British boffin and inventor of pykrete, Geoffrey Pyke, proposed developing screw-propelled transport for commandos in Norway; but his ideas were rejected in favor of a more traditional tracked-vehicle.

Since the propulsion cylinders have to be fairly large, to give maximum contact with the surface; they can also be made hollow, making them double as flotation units. For this reason, screw-propulsion works well for amphibious vehicles that can handle shallow water and mud that conventional boats cannot. A modern screw-propelled vehicle developed in the Netherlands for this purpose is called the Amphirol.

Sources

Bibliography

1. Wikipedia article: Screw-propelled vehicle

Game and Story Use

• This could be used as an exotic form of transportation in the right location.
  • Say, if the PCs are arctic explorers, for example
  • Or using them to traverse a swampy region, or one where receding tides frequently leave difficult-to-traverse muddy flats.
• You might want to refer to the vehicle as an "Amphirol", rather than a "screw-powered vehicle", unless you want your players to be snickering throughout the game.
  • Of course, having a vehicle that is actually powered by sex might be interesting…
    • Except how would you steer it? No, let's not even go there.