I really can't see what good will come from one center managing the ascent stage while another manages the transfer/descent stage.Seems like a recipe for disaster.
Quote from: GWH on 08/14/2019 12:40 amI really can't see what good will come from one center managing the ascent stage while another manages the transfer/descent stage.Seems like a recipe for disaster.What center manages the ascent stage?
No "disaster" in principle, at least. There's this thing called the telephone, and this other thing called the internet, and these documents called CAD files, all of which allow for detailed coordination between the centers.
Quote from: b0objunior on 08/14/2019 12:48 amQuote from: GWH on 08/14/2019 12:40 amI really can't see what good will come from one center managing the ascent stage while another manages the transfer/descent stage.Seems like a recipe for disaster.What center manages the ascent stage?JSC, but Marshall has overall control of the project.
This is how I imagine this working: Marshall will have a relatively unfettered choice of descent stage proposals, and because that's the heaviest piece, the performance of the chosen descent stage (hydrolox vs. hypergolics etc.) will fix the mass budget for JSC's ascent stage. JSC will have much more control over the ascent stage design than Marshall will have over the design of its fixed-cost elements, and the propulsion system they choose for the ascent stage will determine what kind of refueling element they select for the Gateway. Marshall will then need to select a transfer stage which uses the same propellants.
Quote from: JohnFornaro on 08/14/2019 12:30 pmNo "disaster" in principle, at least. There's this thing called the telephone, and this other thing called the internet, and these documents called CAD files, all of which allow for detailed coordination between the centers.There are also departments dedicated to document control which may or may not have separate standards for each center, their own expectations on what and how often things are to be communicated, how they are, and many many hurdles to that simple communication process.Much more complicated is the potential for all these "mom said dad said" situations where any potential decision point may by conflicted by both centers, infighting and rivalries between the two, and much worse overriding of standards resulting in costly and time consuming rework. At the worst both centers will obviously need to agree on decisions, a more time consuming process when it's two parties rather than one, meaning the primary contractor sees more delays.Agile and/or development processes like those in use at SpaceX will be highly constrained if just one center expects milestones to be met resembling a waterfall development process (which happens to be especially susceptible to delays when accommodating a broad user base).Despite the best new technologies to manage virtual work teams, "too many chefs in the kitchen" is a very real barrier to engineering.
So how did the Saturn V work when Boeing made the first stage; NAA, the second; and MDD, the third? Not to mention two spacecraft built by another two contractors.
Quote from: Jim on 08/14/2019 07:20 pmSo how did the Saturn V work when Boeing made the first stage; NAA, the second; and MDD, the third? Not to mention two spacecraft built by another two contractors.Easy Peesy. They made sure not to use the internet.
Quote from: GWH on 08/14/2019 01:56 pmQuote from: JohnFornaro on 08/14/2019 12:30 pmNo "disaster" in principle, at least. There's this thing called the telephone, and this other thing called the internet, and these documents called CAD files, all of which allow for detailed coordination between the centers.There are also departments dedicated to document control which may or may not have separate standards for each center, their own expectations on what and how often things are to be communicated, how they are, and many many hurdles to that simple communication process.Much more complicated is the potential for all these "mom said dad said" situations where any potential decision point may by conflicted by both centers, infighting and rivalries between the two, and much worse overriding of standards resulting in costly and time consuming rework. At the worst both centers will obviously need to agree on decisions, a more time consuming process when it's two parties rather than one, meaning the primary contractor sees more delays.Agile and/or development processes like those in use at SpaceX will be highly constrained if just one center expects milestones to be met resembling a waterfall development process (which happens to be especially susceptible to delays when accommodating a broad user base).Despite the best new technologies to manage virtual work teams, "too many chefs in the kitchen" is a very real barrier to engineering.So how did the Saturn V work when Boeing made the first stage; NAA, the second; and MDD, the third? Not to mention two spacecraft built by another two contractors.
Didn't the latest solicitation specify that bidders are to submit integrated landers - eg. ascent + descent & optional transfer stages? https://www.fbo.gov/index?s=opportunity&mode=form&tab=core&id=5f6768356bb378bce7b3e80cae39cf1f&_cview=0
Looks like things are proceeding swimmingly already: https://www.cruz.senate.gov/?p=press_release&id=4627
As far as I can tell its 2 or 3 stage only. 3 stage is the reference but a 2 stage system is allowable, with abort to orbit capabilities being the driving requirement.EDIT to minimize posts:Looks like things are proceeding swimmingly already: https://www.cruz.senate.gov/?p=press_release&id=4627