Actually, the advantage of the filament wound cases is that you can safely operate them at higher pressures, getting more efficiency out of the propellant. No steel liner at all - it is not needed. We are also going to switch from PBAN to HTPB in the new boosters, so the combination of a lightweight case, higher MEOP, and HTPB propellant provide a significant performance increase over the existing RSRM.

ATK went to the Vulcain engine/Ariane 5 to get a man-rated liquid upper stage with a minimal amount of change needed. That was the driving consideration, not total lift capability.

The ATK capsule will be similar to Orion, but both Orion and Liberty have very little in common with Boeing's CST-100.

We will use the Ares I-X MLP; they are modifying another one for SLS.

Now, I need to figure out how to get my NAR number on the outside....<g>