The spider drive was a revolutionary technology providing a means of space travel without the use of impellers.

Because it did not use impellers, starships using it were almost undetectable in operation. On the downside, the acceleration rates of this new means of propulsion were modest and substantially lower than with traditional drives. Still, the military advantages were substantial.

The spider drive was first developed by the Mesan Alignment in the 20th Century PD.

Basic principle[]

The spider drive propelled the vessel in question through N-space (normal or Einsteinian space). The system used a number of tractor/pressor beams of unprecedented power to pierce and tractor on to the "Alpha Wall" boundary between N-space and hyperspace. By tractoring the hyper wall further in advance of the ship and "pulling" itself along, the ship obtained motion. Spider drives were a very stealthy way of moving a ship, as they produced no gravity field above and below it, thus gravitic sensors were unable to detect a drive signature.

However, any ship crossing the hyper wall between normal space and hyperspace, would radiate a hyper footprint that could be detected. But that footprint could be significantly reduced if the ship took proper care with the transition and made the transition far enough from a sensitive detection grid. The fact that an impeller wedge would then give away the location of the ship normally made such maneuvers impractical. The inherent difficulty in detecting a spider drive made such care much more practical and worthwhile, as shown during Oyster Bay.

However, the spider drive was only effectively capable of imparting a normal space acceleration of around 200 gravities due to a lack of inertial compensators, compared to impellers offering known accelerations of up to 700 gravities or 7kps². Maximum speed was limited, as with most ships, to 0.8c in normal space due to radiation and shielding issues. Thus the lower acceleration meant that it would take a spider drive vessel longer to reach maximum speed, a military disadvantage. A spider drive produced no impeller wedge and no sidewalls, which normally served as the main protection of a starship. (SI2)

Effects on starship design[]

The spider drive required a style of ship building different to that of impeller or reaction thruster powered craft. Mesan spider drive vessels were trilaterally symmetric because of the need for three sets of tractors to stabilize movement. This was a significant departure from the traditional hammerhead design used in the majority of naval construction. The lack of a protective wedge meant there was no unarmored "top" or "bottom," and such ships had three sets of broadside weapons in between their three drive "keels" instead of an impeller drive ship's two.

The spider drive also required improvements on gravitic plating technology, as the vessel in question had no wedge and therefore no gravity sump for an inertial compensator to work with to neutralize the effects of acceleration. Because grav-plates carried the load of compensating for acceleration, spider drive ships were wider, with their decks oriented perpendicular to the axis of motion (i.e. the front of the ship is "up" internally). (SI2)

Known uses[]