This is basically my original concept for the MH12500 Heavy Lift Launch Vehicle standardised module. The baseline stats (basicly the mass budget allowances) are essentially identical to those I noted for the MH12500A module (the more advanced version). Although the mass budget is in the same range, the actual mass and capacity of the MH12500 are somewhat lower than the advanced version (this should be self evident, since the advanced version has the same dimensions, but
squares out the structure toward the exterior).
I have made a few revisions to the design. Instead of a lateral triple tank, I have pulled-in the walls of the first (innermost) pressure vessel to 10m diameter. This is now a single tank, intended to store LH propellant for Earth launch. The second vessel has been brought in to the original 12m diameter, but now serves as an outer wall for a concentric LOX propellant tank. This means that the inner tank now functions as a common wall for both LH and LOX tanks. The benefit of this is that less insulation is required for the LH tank, as there is less temperature differential. Likewise, as the cross-sectional proportions of the two tanks happen to be just about the optimal burn mix ratio (so the propellants will be consumed at the same rate, linearly), the LH tank can be much lighter, as the mass differential is also greatly reduced. The two propellant tanks share common