GURPS Spaceships, in use!

[David L Pulver]

Originally Posted by ectropy

So, I've got a directed question for any of you:

Without superscience, how do you get a colony ship to Alpha Centauri (requires about 4000 mps delta-V)?

At TL9, it seems impossible - even using a magsail for braking (to save half the delta-V requirement), multi-staging like crazy, an Adv Fusion Pulse Drive, and the Delta-V Increase table on page 27, that still gives only 32 mps per stage... which comes to 63 stages.

At TL10, it comes just into possibility - using the same parameters, you get 160 mps per stage, or 13 stages. If the colony ship (final stage with magsail) is SM+10, the whole vessel would be SM+23 when it leaves the solar system. And let's not even mention the cost...

At TL11, it becomes possible to do - same parameters again, leaves us with only four extra stages necessary. When it leaves the solar system, the colony ship (SM+11) with all its boosters is going to be SM+15 or larger.

Antimatter has higher delta-V, but generally the fuel costs so much more than the efficiency increase, that it isn't worth it. The exception might be Antimatter Pion (3400 mps per fuel tank), which means that the colony ship could get there in a single stage, 2 at the highest. Fuel cost is still astronomical.

So... am I missing anything?

A lot of colony ships are in book 5. Quick and dirty to carry a minimum of 500 colonists, try a SM+13 ship set up like this:

Front Hull
[1] Diamondoid armor
[2] Habitat (500 luxury cabins, 100 minifacs, 100 establishments, 100 labs, 2,500 tons cargo.)
[3] Hangar (10,000 tons of landing craft, roll on/off cargo, probes, etc.)
[4] Magsail
[5] Open Space (farms)
[6] Fuel
[core] Control Room

Central Hull
[1] Diamondoid Armor
[2-6] Fuel
[core] Reactor

Rear Hull
[1] Diamondoid Armor
[2-5] Fuel
[6] Adv. Fusion Pulse

It therefore has 10 fuel tanks. At TL11, an advanced fusion pulse drive gets 350 mps per tank. We multiply that by 1.4 for having 10 tanks, which gives us a 490 mps per tank. 490 x 10 = 4,900 mps, and we're off with room to spare!







Suppose you assume that 12 systems of the colony ship will be fuel tanks.