Beowulf wrote:NecronLord wrote:PeZook wrote:It lofts about 112 tonnes to orbit (shuttle+payload in the cargo bay), which is 6-8 tonnes less than the Saturn, but the whole STS assembly also masses 1/3 less. The Shuttle is a pretty impressive vehicle, to be honest, if quite expensive to use.
Indeed. The proposed Ares models use a lot of the best features of shuttle technology. Particularly its solid booster first stage.
I thought the solid booster first stage was one of the worst features of shuttle technology. They're reusable in a sense, but require essentially complete refurbishment of the booster for reuse. It's almost as cheap to just build a new booster. It's responsible for half the failures of the STS. The way they're using the booster in Ares I essentially requires reengineering the fuel grain, which isn't cheap.
This is wrong in several ways. Most RSRM parts are reusable about twenty times (the nozzle thrust bearing for ten); many of these are massive complex forgings and are not at all cheap. It is, in fact, nowhere near as cheap to build a new booster. This has been studied time and again - if, as you say, it's as cheap to build new ones each time,
NASA would do just that.
The solid rocket motors have never failed under the conditions for which they were designed. Blaming Challenger on the boosters is like blaming Ford for your car sinking when you tried to drive across a lake.
The expansion of the four-segment booster to the five-segment RSRMV for Ares is cheaper than any other options examined - that's why NASA picked it. The reshaping of the grain structure is easily performed, and parts commonality between RSRM and RSRMV is in excess of 80%.
Infrastructure commonality is higher, which of course is where the savings come in.