@80mileshigh and Solarliner
80mileshigh asked me, and so im giving you and Solarliner the permission to use my Deepstar- and Lander-config.
I calculated the fuel mass to 12751mT, Sky captain did own calculations and got 13500mT. So you can set it between 12760 and 13500mT. It has no big effect. But i propose to increase the Isp to get more DeltaV! If we use Isp 200000 we get dV of 400km/s, before only 193km/s. But the acceleration goes down to 1,28m/s², well enough for that huge ship (before 2,8m/s²) because a fusion drive can run like an afterburner. We give fuel directly into the plasma beam, the fuel consumption rate goes high and the thrust increases, but the exhaust velocity (ISP) falls down.
You can test some settings, but alltime use the same multiplier/divider for Isp, thrust AND attitude thrust. Ofcourse higher Isp numbers enabling more comfortable travel speeds, but maybe TransX and IMFD getting trouble, because they are not made for low thrust vessels.
Perhaps my head is fuzzy, but are you suggesting a two-mode switchable engine (afterburning and non-afterburning) ? Because that's totally do-able. :thumbup:
There could also be a function for [math]I_{sp}[/math] variation based on throttle setting.