[Spaceships] Getting A Few Thousand Extra MPS

[mlangsdorf]

Going by the Spaceships rules, you can put 14 systems in a detachable lower stage, 1 of which must be an engine and 1 of which should probably be an armor system to represent the ship's hull structures. A fusion rocket (SS1 p 23) gets 60 mps per tank at TL 10, and a spaceship gets a 40% bonus to delta-V for having 9-12 tanks. So 12 tanks will get you to 1008 mps, which is a little more than half of what you need for a ramscoop to work.

So you're looking at a 5 stage design. Assuming a not-crazy 3,000 ton survey craft at the destination, you have a stack:
Stage 5: SM +9 Survey craft with ram scoop which is the upper stage for:
Stage 4: SM +10 collection of initially empty fuel tanks which are the upper stage for:
Stage 3: SM +11 collection of initially empty fuel tanks which are the upper stage for:
Stage 2: SM +12 collection of full fuel tanks which are the upper stage for:
Stage 1: SM +13 collection of full fuel tanks.

So you have an initial ship that is roughly the size of the largest real world oil tankers (300,000 tons) which accelerates at .01 G to 924 mps, which takes 6 months. It then drops Stage 1, slimming down to the size of a nuclear aircraft carrier, and accelerates at 0.01 G for another 6 months to a total 1848 mps. Second stage is discarded and the ramscoop opens up, allowing continual acceleration for the next 20 years or so, reaching a top speed of about 0.2c, well below relativistic effects.

The next bit is tricky - the engines need to do a retrograde burn while the ship the ram scoop is still pointed in the direction of travel. Maybe there's a rear mounted ram scoop for this? Regardless, another 20 years of deceleration drops the speed down to just under 0.01c and the ram scoop shuts down. Burn all the fuel in Stage 3 to get down to 924 MPS and discard it, then keep burning fuel. Assuming that the speed of the target system is only a few MPS relative to the departure system, the 3,000 ton survey craft has arrived in only 40 years or so.

Most of that is back of the envelope math, and Spaceships is an approximation of a design process. But if you accept the Spaceships numbers as being more-or-less realistic, then you can travel 4 light years in 40 years or so at TL 10 without using superscience, though it will cost you over 10 billion GURPS dollars, and that's just the cost of engines and fuel tanks that you're discarding along the way.