Do you have LOC\LOM number for new J-246?
Is the Direct team not leading themselves open if they switch to the J-246, like NASA that they keep on refining their plans? All good, PM know that Planning is good, and there will be refinement as you know more but at some point you have to implement. Is the Direct team basically saying that the Constellation team really needs to revaluate the whole program due to the wrong assumptions that they made in the ESAS study. That would take a strong leader at NASA to say, we may have made a mistake in the ESAS study.
Would SSME Jupiter be v3.0?
I am pleased to announce that by almost unanimous vote of both our engineering team and our public team together, we have decided to break with the Constellation Program's baseline choices and DIRECT is officially moving to a position of baselining the Space Shuttle Main Engine as our primary Main Propulsion System for the Jupiter launchers.The provisional plan for Jupiter is to utilize older flown SSME's during the testing phase of the program and some early IOC flights, to build some new SSME's and then at some yet-to-be-determined point in the future to fund a new development program intended to reduce the production costs of the SSME.The cost for the SSME, per unit, is higher than the RS-68, although it completely avoids all up-front development costs and schedule impacts, so overall it is a much faster and cheaper alternative in the short- to -mid-terms. In the quantities which DIRECT plans to build the SSME's, their production costs significantly drop compared to current low-volume production runs used previously for the Shuttle Program.When re-developed into a cheap alternative in the future, the cost profile is extremely competitive with the RS-68 Regen, yet offers significantly greater performance in the Jupiter configuration.The RS-68 option does not completely 'disappear', but becomes the secondary option instead of the primary.Switching to the SSME for our baseline does not imply any change at this time regarding using the J-2X verses the RL-10 or even an RL-60 option. At this moment the J-2X remains our baseline, although discussions are on-going.Ross.
Sad to say, the "fall back" to RS-68 would be a little disappointing at this point!
Is there -any- advantage the J-2X would have in the Direct Architecture?
I can see three advantages of using the J-2X over the RL-10 engine for the Jupiter EDS:
The J-2X is a very large engine. The nozzle is roughly the same size as the nozzle on the F-1. It's much bigger than would be needed on an EELV, unless you wanted to triple their payload to LEO or something.
J-2X Powered Upper stage on a Delta IV heavy? How much Could that lift to LEO? TLI?Cargo only perhaps.. max G's would have to be high at 100% thrust.Could you even get it off the pad with enough fuel in the US to do you any good?
Quote from: yinzer on 03/28/2009 03:31 pmThe J-2X is a very large engine. The nozzle is roughly the same size as the nozzle on the F-1. It's much bigger than would be needed on an EELV, unless you wanted to triple their payload to LEO or something. J-2X Powered Upper stage on a Delta IV heavy? How much Could that lift to LEO? TLI?Cargo only perhaps.. max G's would have to be high at 100% thrust.Could you even get it off the pad with enough fuel in the US to do you any good?
Quote from: TrueBlueWitt on 03/28/2009 04:16 pmQuote from: yinzer on 03/28/2009 03:31 pmThe J-2X is a very large engine. The nozzle is roughly the same size as the nozzle on the F-1. It's much bigger than would be needed on an EELV, unless you wanted to triple their payload to LEO or something. J-2X Powered Upper stage on a Delta IV heavy? How much Could that lift to LEO? TLI?Cargo only perhaps.. max G's would have to be high at 100% thrust.Could you even get it off the pad with enough fuel in the US to do you any good? No. The J-2X is only going to be useful if you are trying to lift very heavy payloads, fifty tons or more. The EELV lower stages are not big enough for such payloads. The only reason J-2X could be used on Ares I was because the SRB was so undersized.It's also worth noting that going to the J-2X was instrumental in the imminent downfall of the Ares I. Putting paper engines squarely in the critical path of your new launch vehicle when you don't have to is not wise.
Quote from: MP99 on 03/28/2009 08:51 amSad to say, the "fall back" to RS-68 would be a little disappointing at this point!Only if you want a new upper stage, not if you go with L1 rendez-vous. No new engines, no new upper stage, cheaper and fewer engines. But to be honest it's not so much the cost I care about (since you guys are paying), it is the impact on depots and international / commercial manned spaceflight.
SSME J-130 can lift a lot more mass to orbit than RS-68 J-120 without developing an upper stage at all.Add in a separate 55m/s circ burn post-ascent, and you're looking at 2:1 in favour of SSME (93mT+).
If you want an architecture without an upper stage, why would you prefer an RS-68-based core?
Quote from: robertross on 03/28/2009 12:34 amWe were always told Orion won't be ready before Ares-I.Robert, I think you have been mis-informed.Orion could always have been made ready before Ares-I. CxP have restricted its budget so that it is designed to finish at the same time as it's launcher will, but that really is an artificial limitation.The long-pole for the pair has always been the development schedule of the J-2X engine, followed by the schedule of the 5-segment booster.Ross.
We were always told Orion won't be ready before Ares-I.
Robert,RL-10 already requires human-rating anyway, for the Altair LSAM.