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marsavian
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« Reply #2760 on: 10/25/2009 08:01 PM » |
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This was your easy cheap Direct v1.0 engine specification remember ?
We had a cost allocation of $1 billion set aside for it, with an additional margin of $750m.
I'm not sure I'd call that "cheap" 
Ross.
Shared with the DoD and Delta IV it might be  .
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Downix
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« Reply #2761 on: 10/25/2009 08:27 PM » |
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This was your easy cheap Direct v1.0 engine specification remember ?
We had a cost allocation of $1 billion set aside for it, with an additional margin of $750m.
I'm not sure I'd call that "cheap"
Ross.
Shared with the DoD and Delta IV it might be .
What would the DoD gain from such a project, after already sinking millions into the RS-68A? The Regen does not offer the DoD any advantage to their existing program, and only increases cost to operate.
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marsavian
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« Reply #2762 on: 10/25/2009 08:33 PM » |
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This was your easy cheap Direct v1.0 engine specification remember ?
We had a cost allocation of $1 billion set aside for it, with an additional margin of $750m.
I'm not sure I'd call that "cheap"
Ross.
Shared with the DoD and Delta IV it might be .
What would the DoD gain from such a project, after already sinking millions into the RS-68A? The Regen does not offer the DoD any advantage to their existing program, and only increases cost to operate.
Long-term price reductions due to shared usage with NASA and greater performance.
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Downix
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« Reply #2763 on: 10/25/2009 08:37 PM » |
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This was your easy cheap Direct v1.0 engine specification remember ?
We had a cost allocation of $1 billion set aside for it, with an additional margin of $750m.
I'm not sure I'd call that "cheap"
Ross.
Shared with the DoD and Delta IV it might be .
What would the DoD gain from such a project, after already sinking millions into the RS-68A? The Regen does not offer the DoD any advantage to their existing program, and only increases cost to operate.
Long-term price reductions due to shared usage with NASA and greater performance.
I have not seen figures for greater performance, do you have any?
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marsavian
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« Reply #2764 on: 10/25/2009 08:39 PM » |
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As long as there has been no reduction in thrust the higher Isp (435s/418s vs 414s) will automatically give greater performance.
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Downix
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« Reply #2765 on: 10/25/2009 08:41 PM » |
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As long as there has been no reduction in thrust the higher Isp (435s/418s vs 414s) will automatically give greater performance.
To take advantage they'd have to re-design the Delta IV into a new Delta V design, as you'd run out of fuel before you took full advantage of the added isp.
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marsavian
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« Reply #2766 on: 10/25/2009 08:43 PM » |
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As long as there has been no reduction in thrust the higher Isp (435s/418s vs 414s) will automatically give greater performance.
To take advantage they'd have to re-design the Delta IV into a new Delta V design, as you'd run out of fuel before you took full advantage of the added isp.
Higher Isp means you use less fuel to get the same performance. Your statement is wrong.
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adamsmith
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« Reply #2767 on: 10/25/2009 08:45 PM » |
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This was your easy cheap Direct v1.0 engine specification remember ?
We had a cost allocation of $1 billion set aside for it, with an additional margin of $750m.
I'm not sure I'd call that "cheap"
Ross.
Shared with the DoD and Delta IV it might be .
What would the DoD gain from such a project, after already sinking millions into the RS-68A? The Regen does not offer the DoD any advantage to their existing program, and only increases cost to operate.
Long-term price reductions due to shared usage with NASA and greater performance.
If you could achieve 435s isp, it might be worth it, but lets CLOSE THE GAP with the SSME. By the way, has every one seen the video linked through www.directlauncher.com supporting option 4B. I presume the support for option 4B is because that is the only one that CLOSES THE GAP. Why didn't they set up 5C to also close the gap? Seemed natural to me. Stanley
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Mark S
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« Reply #2768 on: 10/25/2009 08:51 PM » |
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So now all of a sudden DIRECT has to be able to match a dual Ares-V Lite launch, instead of the CxP 1.5 capability? Talk about moving the goal posts!
It's really ridiculous that we have to keep putting up with this crap. I'm surprised that Augustine let his committee get shanghaied by the NASA NIH crowd. There is absolutely no justification for a requirement to match the capacity of a dual Ares-V Lite, just as there is no justification for the requirement for the separation of Orion from any other spacecraft (Altair and EDS). Strangely enough, the panel is not calling for this alleged "CAIB requirement" for Ares-V Lite, only for all the other launchers. Hm.
Can an Ares-V Lite launch without an upper stage and still put Orion plus 30 mT of payload to LEO orbit? Can Ares-V Lite be built using existing tooling and facilities? Can Ares-V Lite be accommodated by existing transport infrastructure? Can Ares-V Lite use 4-segment RSRBs or 5-segment RSRBs, depending on the mission requirements? Can Ares-V Lite be built and flown with existing man-rated main engines? Can we afford to launch two Ares-V Lites for every lunar mission, when the 1.5 plan was already too expensive?
All this tells me is that NASA is not pro-actively thinking about the best way forward, they are reacting to events and trying to save their Precious.
So the question is, will B1 and B2 fall for it like Augustine did? Or will they see the FUD for what it is and deal with it accordingly? Only time will tell.
My thanks to Ross, Chuck, and the entire DIRECT team for continuing to fight for the survival of the American HSF program. Give 'em heck!
Mark S.
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robertross
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« Reply #2769 on: 10/25/2009 09:02 PM » |
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All this tells me is that NASA is not pro-actively thinking about the best way forward, they are reacting to events and trying to save their Precious.
Mark S.
I would say the new HLV review started by Gen Bolden 'might' have a thought on the matter. I think HE wants proof of the best way forward. If we are indeed starting with a new slate, he won't tolerate 'silliness' to go on under his watch.
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robertross
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« Reply #2770 on: 10/25/2009 09:02 PM » |
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You're wrong
p13-14
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20070002798_2007001569.pdf
That very neatly demonstrates that only if you're fixated on the "1.5 launch" architecture, do you actually need gargantuan performance.
In a two-launch architecture, that clearly shows that you can still easily achieve the same goals with the smaller configuration.
Thanks for reminding me about those charts. I can use them in my presentation Tuesday...
Ross.
More presentations?? Man, I don't know how you do it.
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alexSA
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« Reply #2771 on: 10/25/2009 09:12 PM » |
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280mT for a lunar mission? Total crap. Completely unnecessary.
Whether it's necessary or not is irrelevant. The point the Augustine report was making is that if you have Ares V Lite, only a dual launch scenario makes sense, as a 1.5 launch scenario with Ares V Lite doesn't work. But if you account for 2 Ares V Lite per crewed mission, you need to start comparing this scenario to something comparable with J-241 or J-246. 2 J-241 evidently would mean a crewed mission that falls short of the capability and margins of a 2-launch Ares V Lite mission. All that being said, of course you could also try to compare a scenario of 6 Ares V Lite vs. 6 J-246 which results in about comparable engine costs. But 6 J-246 per year is a much more limited architecture than a 6 Ares V Lite per year architecture.
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Downix
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« Reply #2772 on: 10/25/2009 09:28 PM » |
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As long as there has been no reduction in thrust the higher Isp (435s/418s vs 414s) will automatically give greater performance.
To take advantage they'd have to re-design the Delta IV into a new Delta V design, as you'd run out of fuel before you took full advantage of the added isp.
Higher Isp means you use less fuel to get the same performance. Your statement is wrong.
You are assuming that the RS-68 Regen will get more isp than the RS-68A however. But you post the isp for the RS-68A here. So, again, what is the advantage of a longer burn time between two engines of the same isp, assuming that the RS-68 Regen has the same isp as the RS-68A. Now, if the Regen can get a further performance improvement, well, then you can get the DoD interested. So far, however, I have not heard of that.
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robertross
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« Reply #2773 on: 10/25/2009 09:32 PM » |
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280mT for a lunar mission? Total crap. Completely unnecessary.
Whether it's necessary or not is irrelevant.
It is TOTALLY relevant! The whole reason we have the choices before us are based around the required mass to orbit, TLI, and beyond. It's the one reason why PD makes so much sense going forward: develop a base architecture that can be scaled up over time to launch the necessary mass in sizable chunks that are affordable over the long term. That's the beauty of Direct: it is 100% scalable, and one of the most affordable options out there.
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kraisee
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« Reply #2774 on: 10/25/2009 09:33 PM » |
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You always need to start with your REQUIREMENTS if you are ever to have any chance of realistically assessing any architecture at all.
Failing to define any REQUIREMENTs at all is the #1 Category A mistake which the Committee made.
The entire comparison of this 280mT pseudo-requirement completely breaks down when you factor in the additional cost of the larger lander which can utilize the 280mT of lift performance.
The total mass in LEO has never been an official REQUIREMENT. It's the total mass heading towards the moon which is the only real REQUIREMENT.
For CxP, the 45mT lander currently being designed is expected to be a $4-5bn per year program -- and we can't even afford that!
A lander 50% larger simply isn't an affordable proposition.
The *underlying premise* of this particular comparison is therefore a completely BROKEN one.
What the committee should have done is find out what it takes for each architecture to accomplish the mission REQUIREMENTs.
The current mission requirement are defined by CxP 70000 Constellation Architecture Requirements Document (CARD) Rev 3 Change 001, March 2009 (available on L2).
That document currently specifies that at the time of a TLI, the lander must mass no more than 45,000kg, Orion mass 20,185kg, ASE mass 890kg and there is 5,000kg of Manager's Margin included for safety. That's a grand total of 71,075kg or 71.1mT of total spacecraft mass being pushed thru TLI.
71.1mT thru TLI is the official NASA CARD REQUIREMENT as it stands today.
If they had done their job properly, the Committee should have spent their time studying how much each option costs to accomplish the ACTUAL REQUIREMENTS.
If they had done the job properly, they would have found that the current Ares-I + Ares-V architecture can simply not meet the performance REQUIREMENT at all.
If they had done the job properly, they would have found that while Dual Ares-V Lite can exceed that performance, there is no cost profile which allows that excess performance to be utilized, so the vehicles would have been overly expensive for the actual REQUIREMENT.
If they had done the job properly, they would have found that 4 Advanced EELV's could have done the job, but the cost for four launchers is quite high to meet the REQUIREMENT.
If they had done the job properly, they would have found that Side-Mount SDLV could not actually deliver the required masses of those specific spacecraft & associated propellant in just two flights, so would have required a third -- which is similarly too high to meet the REQUIREMENT.
If they had done the job properly, they would have found that an In-Line solution can deliver the correct REQUIREMENT masses to both LEO and to TLI in just two launches. Further, it costs no more to develop & operate than the Sidemount option -- and costs considerably less than any Ares configuration.
IF they had done the job properly.
Ross.
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