The questions about the survival chances of a "hostile terraforming starship" made me wonder about the other side of the coin -- how do you build a stopgap spacefighter?
Take a civilization at TL6 to TL9, with a modest space exploration infrastructure, and perhaps even some belt mining, but no military space assets except for C3I sats and ASATs near the homeworld. Now they are seeing something threatening or just alien in the skies, and they want to get prepared in a hurry. One of the books which formed my passion for science fiction was Spacecraft 2000 to 2100 AD, since re-released as Spacecraft 2100 to 2200 AD with computerized graphics for a RPG. The original contained this picture by Jim Burns: http://jfjacobs.com/Gallery/albums/SciFi-05/0uro0046_jim_burns.jpg The new version lacks the extensive damage to the launch site (a car flying around ...) which is probably more realistic but less fun; it gave the feeling of a desperate crash project. * What can be done, with the TLs as written in GURPS 3E or 4E? The answer to this question is probably "more than you would think" if you ignore real-world constraints. TL6 could see shuttles on top of multi-stage boosters, with a better than even chance of surviving re-entry. They could be turned into aerospace fighters or carry stuff for orbital fighters and a station. TL7 allows expeditions into the outer system, and TL8+ even more so. * What can a crash R&D project develop in a few months or years, even with a wartime economy? Those TL6 shuttles will have an abysmal payload-to-weight ratio, and it gets worse if there is no time to iron out the bugs and half your loads explode. At all TLs, simplicity would be the key to integrate systems in a hurry. * On the plus side (from the starfighter viewpoint), you could probably ignore some environmental concerns, survival comes first ... from TL7 up, Orion ships could be an option (see Footfall by Niven and Pournelle, or Orion Shall Rise by Anderson). On the other hand, they would not know for sure that the ETs are bad until the first overt act, and ruining your world on a maybe might be unwise. * It could be suicidal for a TL9-, non-FTL civilization to pick an avoidable fight with a TL10+, FTL civilization, so "use it or lose it" systems are iffy. Of course there might be no other way -- when lower-TL forces go against good higher-TL forces, their losses are going to be appalling even if they win. My tentative goal is to write local defense craft, with a crew size of half a dozen at best (your typical gaming group), and the option to talk rather than shoot if talking is possible, so it will need more than a few hours endurance. Orbital deployment or surface launch? * Much depends on the scenario, but surface bases are easier to hide or harden. * On the other hand, surface bases concede control of the outer system to the aliens. What deviltry can they come up with in the belt? * Positioning assets in orbit once an alien "embassy ship" is there could be interpreted as a hostile act -- do THEY know that WE know that THEY know WE have to use or lose them? What armament? * From TL7 upwards, there will probably be nuclear missiles in the mix, since they can inflict massive damage without a big delta-V. Enemy point defenses must be saturated by multiple warhead bus missiles (MIRV, except there is no R) and salvo launches. * Kinetic warheads, launched by missiles or railguns, might be adapted from existing ASAT systems. But can a load designed to kill a spy sat (a cloud of ball bearings?) handle a large starship? * Point defenses on the spacefighter could allow it to survive until launch, and perhaps even to wait for the invader to strike first. At TL7, this means gatlings, at TL8+ probably lasers or railguns. Lasers are less likely as atmospheric point defense systems, and there might be no time to build new ones. * The other TL8 beam weapons are masers and particle beams. A big neutral particle beam will probably take too much R&D, even if it feels nicely cinematic. What sensors? * Radar, since it provides exact range and speed if there are good returns. Also the best off-the-shelf system at TL6/TL7. * Thermographs, since thermal emission cloaking in space is anything from iffy to impossible. RAM might work against radar, but heat will leak out. * Optical, for extra detail before the strike. What engines? * TL6 means chemical rockets. * At TL7, chemical rockets are the only way to get into LEO. From orbit outwards, fission rockets might be an option. * At TL8, there is much greater choice. Chemical rockets are still likely for atmospheric takeoff, but fission rockets, either with gas core (VXii9) or without gas core (VE36), and nuclear pulse drive (VXi13) have the power for surface launches. Isp and engine weight suggest the nuclear pulse drive, with gas core fission second and ordinary fission last, but would there be off-the-shelf drives with enough thrust to take a fighter into space? Is radar stealth worth trying? * Developing a stealth airframe takes longer than ignoring this requirement. How will the stealth material react to reentry? * Hiding a TL9- craft against large TL10+ starships with their powerful sensors could be futile even if stealth was possible in space ... Comments? _______________________________________________ GurpsNet-L mailing list <[email protected]> http://mail.sjgames.com/mailman/listinfo/gurpsnet-l
