[kreios]

I'll answer to the relevant points here.

Originally Posted by ericthered

I'm not sure why you're using a fusion torch instead of a fusion rocket. the rocket has 4x the delta-v. Do you need the speed?

The acceleration, yes. If you only look at the departure burn, the Fusion Rocket needs more than eight hours thrust to produce the necessary dV (which means even more time spent on waiting for periapsis). The torch needs five minutes of thrust.

I'm surprised to find out that using water is cheaper than hydrogen, but the math holds up. Even counting transport costs, water is half the dv for 1/50th of the price, and you only decrease cargo space by 25%, so it makes sense. And you probably don't even need pure water: melted ice from an icy moon like Europa will work.

So was I, but - assuming waystations - hydrogen is far too expensive. If I remember correctly, there's a break-even point somewhere between five and ten jumps, so maybe for exploration craft - but on the other hand, they'd have to deal with the hassle of cryogenic hydrogen.

I'm sad to see you drop the FTL "emerging at rest" mechanism. I was having a lot of fun with it.

Hm... maybe I should spend a post looking over that mechanism and computing the dV. It might be worth keeping.