Yeah it's frustrating how little is public about this thing.
That thread on NASASpaceFlight is also where the mass figure comes from.
Best guess from the rocketplane xp sources are that the RS-88 is KeroLOX, so if that's true RCS and retros are probably going to be something else.
As for the size issue. unless I'm mistaken this thing shouldn't be that much bigger than the 4.6m shuttle payload bay. Maybe try throwing it on one of the delta add-ons to make sure?
That thread on NASASpaceFlight is also where the mass figure comes from.
Best guess from the rocketplane xp sources are that the RS-88 is KeroLOX, so if that's true RCS and retros are probably going to be something else.
As for the size issue. unless I'm mistaken this thing shouldn't be that much bigger than the 4.6m shuttle payload bay. Maybe try throwing it on one of the delta add-ons to make sure?