>>12256896They should’ve made the Atlas V core 8 meters wide and used the revived F1Bs on it. That plus a balloon J-2X upper stage can give you 70 mt into LEO, and 101 do you use 4 Atlas V cores with an F1 engine as a boosters.
>BUT WAIT! EXPENSIVE!!!!The F-1B’s that Dynetics pushes costed $15 million apiece. 6 of them (2 on the core and 1 for each booster) would cost $90 million - less than the cost of a single SLS SSME. Also the J-2X upper stage engine isn’t that bad either.
>DEVELOPMENT COSTS ARE HIGH!Maybe. But as of 2010 the J-2X was only five years away from completion anyways and had already been fired a few times. Also the cost of developing the new F-1Bs would probably not be cheap, but it likely would’ve been around “just” $1 Billion. It took that much to restart production of the SSME and they’ve already flown! But I could see engine development cost being more seeing as you have to build 1 engine from (mostly) scratch and another is embryonic.
>ITS NOT SHUTTLE DERIVED!!!!Neither is the SLS. The SLS core uses entirely different metals and was redesigned to support top loads. Aside from the tooling, it has nothing in common with the shuttle external tank. The boosters are also very different. More than just adding another segment, they redesigned the propellant and the insulation material of the boosters, as well as their nozzles. At this point the only thing they have in common with the Shuttle SRBs are their steel casings.
For our hypothetical launcher, we can reuse the shuttle tooling to give us a Kerolox stage that is the same height as the Atlas V first stage (short) but is very fat. We know this is not very expensive, because ULA scales up an Atlas V first stage for Vulcan while keeping Development costs at around $1 Billion. There’s no way this would cost more than SLS.
Developing the upper stage would see a Centaur basically being made fat and given a new engine.
