Onno Meyer wrote: > An interplanetary ship which goes interstellar without proper > preparation is doomed to starvation or worse. A few tons of > special supplies should do wonders.
True enough. >> Right; but what about year-long trips? At 10G, a ship would take >> about 13 months to reach a destination that's one parsec away; 19 >> months for two parsecs; 23 months for three parsecs. These would be >> non-stop trips. I don't doubt that a ship that's designed with >> week-long trips in mind could manage such distances without breaking >> down; but there's the matter of food supplies: such ships probably >> won't be equipped with stasis tubes, and aren't likely to be carrying >> enough food to feed the crew for a year or two (or more, if you need >> to go more than three parsecs out in one hop). > > I was thinking of a factor of ten or so -- months instead of > weeks, years instead of months -- and a well-prepared flight. > Provisions might take ten on twenty percent out of the cargo > capacity, or even less. > > 13 months are 400 days. So a ship designed for 40 days and > ample safety margins should be able to do a parsec if push > comes to shove. 40 days sounds like an outer-system craft. 40 days at 10G is nearly 2000 AU; 13 days at 10G is approximately 200 AU; and 4 days at 10G is approximately 20 AU. Every planet in the solar system is within ten days' travel of every other one; and everything within the orbit of Saturn is within four days' travel. In-system ships are more likely to be designed for four days and ample safety margins, rather than 40 days. >> I've stated that the thrust-to-mass ratio of the drives is on the >> order of hundreds of Newtons per kg of drive; probably not more than >> 300N/kg, and possibly as low as 100N/kg. Power-to-thrust requirements >> should be somewhere between 1kW/10N and 1kW/100N, and field >> maintenance requirements should be negligible in interstellar space, >> and possibly in interplanetary space as well. >> >> With those assumptions, what sorts of spacecraft could you design? > > Call it 200 N per kg of engine/power pack. A ship capable of > 10 G acceleration would be roughly 50% engine. > > I'm assuming that quarters, life support and provisions are > proportional to the crew size. > > That leaves the required hull/armor as a major decision. If > it takes many meters of ice or steel to survive the hazards > of interstellar flights, small ships become impractical and > up-armored ships will be hard to tell from regular ones. Hmm... true. Spaceships 5 gives guidelines for how much of a hazard interstellar gas is at various fractions of lightspeed; but I have no idea how much of a hazard it would be for a warp bubble ship. Do particles enter and exit the bubble at rest, or does the transition impart them with some kinetic energy? If the former, how much of a buildup of interstellar gas at the bow if the ship could occur before it starts getting dangerous? (As well, how much of a buildup would need to occur before it starts becoming useful? Such a ship might be able to use its warp bubble as part of a narrow-channel interstellar ramscoop, without the need for huge magnetic fields to redirect the gasses.) The first issue is whether or not dangerous speeds are attainable in a year or so; if they are, armored hulls would be necessary for all interstellar journeys. If dangerous speeds require a decade or more of acceleration, then there could potentially be hundreds of star systems that you could visit without having to choose between armoring your ship or coasting part of the way. -- Jonathan "Dataweaver" Lang _______________________________________________ GurpsNet-L mailing list <[email protected]> http://mail.sjgames.com/mailman/listinfo/gurpsnet-l
