[gurps] [VEHICLE] Building a hard-SF interstellar ship?

[Roger Burton West]

On Wed, May 02, 2007 at 04:02:37AM -0400, DataPacRat wrote:
>I've recently purchased GVB, and have been playing around with it. My
>most recent idea was to see if I could put together a design with the
>criteria: TL8, no superscience, carrying at least two people in a
>luxury suite from the Solar System to Alpha Centauri. To make it more
>interesting, I wanted to do so in as little time as possible - which,
>effectively, means maximizing the delta-vee.

In other words, picking the engine with the highest specific impulse
(see VxII).

>After some experimenting, the drive that seems to offer the most
>delta-vee per pound of fuel at TL8 is the Orion...

That has an (American-style) specific impulse of 400,000seconds at TL8
(maximum - you can't quite reach this, but you can get arbitrarily
close). A fission fragment rocket from VxI has a specific impulse of
1,000,000seconds. Worth considering? (One "2% of drive mass" fuel load
per 8,000 hours of operation.)

>(Fully-loaded LWt times
>burn time giving a delta-vee of 3,204,600 metres/second.)

Um, no. The whole point is that you lose mass as you go along. See VxII
again:

delta_v=21.8 * ISp * ln (1 + (fuel weight / dry weight)) in mph.

GVB can handle this - you just need to set vTOTAL_FUEL (I think) to the
fuel mass, with a link node.

You might want to think about a spin habitat too.

R