tlb wrote:ThinksMarkedly wrote:It might not be. My theory is that two sides would have been enough to get movement, but three is better and four is overkill. Your own explanation would allow for moving with just two, because they are parallel to each other. But it might be unstable, because no system is perfect, so it requires more work / energy to keep it going.
If we assume that the tractors on the spider stick straight away from the ship with an angle toward the front, then you would need three sets in order to maneuver in three dimensions. Two sets on opposite sides of the ship would only allow you to maneuver in a plane.
Well unless you also had some way to roll the ship; as rolling would change the alignment of the plane your two sides of tractors were pulling moving on and thus enable maneuvering in all 3 dimensions. (And you wouldn't necessarily need to use thrusters for that rolling. While anchored by the tractors you could spin up an internal gyrostabilizer, and then after releasing the tractors push against it to rotate the ship before reengaging the tractors; alternatively if you could give the tractor mounts some degree of lateral freedom then the side angle of the tractors could be enough to induce a rotation)
But the 2 side spider is more of a hypothetical engineering solution; rather than a good way to design a warship. Going with 3 sides gives you better ability to stabilize against unwanted lateral motion and provides full pitch and yaw control without having to first roll the ship.