What's the difference? Do you personally have the engineering qualifications to pass judgement on either the JUS design or his unqualified support for it? There are only a handful of design engineers in the world with his level of expertise. If you are one of them then I would like to meet you.
But why and how is pressurization relevant? Surely you can tell us now... it's not as if Chuck can declare it one way or the other depending on your answer at this stage.
Or if pressurization fails during ascent.
Quote from: Will on 01/14/2009 03:00 pmIt has implications for ground processing. Pressure stabilization is an important ingredient of current and past Centaur stages. If he believes and will state that the JUS can achieve Centaur-like mass fraction without any use of pressure stabilization in ground handling, that's important information for a layman evaluating the practicality of the design.If he is assuming that there *will* be some use of pressurization, that's important information as well. But why and how is pressurization relevant? Surely you can tell us now... it's not as if Chuck can declare it one way or the other depending on your answer at this stage.
It has implications for ground processing. Pressure stabilization is an important ingredient of current and past Centaur stages. If he believes and will state that the JUS can achieve Centaur-like mass fraction without any use of pressure stabilization in ground handling, that's important information for a layman evaluating the practicality of the design.If he is assuming that there *will* be some use of pressurization, that's important information as well.
I think that everyone will agree that supporting someone's opinion without actual numbers is foolish. I don't claim to have his level of expertise, but physics is physics and numbers don't lie (they are only interpreted). My issue is not that the design (centaur) is invalid, rather than unless it has had a detailed loads analysis done with detailed finite element models of the actual hardware, then it's just opinion. If you have done this analysis, please let me see your documentation (I am hoping it is in the rebuttal).Futhermore, I think it would help DIRECT's credibility if someone could compile a list of documents which prove DIRECT's viability. The NLS documents are a great example, if you have more LM upper stage documents proving DIRECT's suitability it would help to know that they exist (and are compiled in one place for easy reading).Marc
I was fairly certain that in this context, pressurization implied "balloon tank" which Ross and Clongton assured us was NOT a part of the JUS. This is a departure from the "standard" Centaur.
Quote from: jarmumd on 01/14/2009 04:06 pmI think that everyone will agree that supporting someone's opinion without actual numbers is foolish. I don't claim to have his level of expertise, but physics is physics and numbers don't lie (they are only interpreted). My issue is not that the design (centaur) is invalid, rather than unless it has had a detailed loads analysis done with detailed finite element models of the actual hardware, then it's just opinion. If you have done this analysis, please let me see your documentation (I am hoping it is in the rebuttal).Futhermore, I think it would help DIRECT's credibility if someone could compile a list of documents which prove DIRECT's viability. The NLS documents are a great example, if you have more LM upper stage documents proving DIRECT's suitability it would help to know that they exist (and are compiled in one place for easy reading).MarcI have no connections do DIRECT, so cannot speak for the actual team, but I imagine a request such as yours will not be granted in its entirety.Typically, complex pieces of engineering carried out by private enterprises contain boatloads of proprietary info that no company will ever let go public. If you want access you have to sign Non-Disclosure Agreements (NDAs), and breaking an NDA is a very bad thing. I find it a stretch to believe that companies like Boeing and Lockheed Martin would want detailed numbers on their upper stage performance posted on Internet forums.This is the dilemma facing "public interest" projects like DIRECT. They need as much publicity as possible to stand a chance in the face of much larger, resource-rich organisations, but at the same time they cannot betray their backers. The end result is that there are always doubters who claim (sometimes with justification) that the cause being presented is mere smoke and mirrors.I believe that DIRECT's ultimate aim is a peer review of all the options (Ares, DIRECT, EELV, etc) carried out by impartial people with appropriate credentials. These people could sign NDAs and thus see all the data.Andrew
clongton, I think you make a very valid point.For a very long time, DIRECT took hits for using "anonymous" sources for your information. You spent a long time explaining/defending yourselves on this front. Now, you add a "named" source, and the accusation shifts to his credentials and whether or not he "missed" something. At some point, people need to either accept or reject these things on their own terms but stop the endless triangulations. There may or may not ever be a "tipping point" that resolves the issues to the questioner's satisfaction.
I have a question though regarding that. When we talk about a "fair" review of the alternatives (which DIRECT is of course a part of) how can we ensure that from NASA all the way through the contractor base that the preferences for LV aren't driven by "what does best for our business" and instead what is the best configuration in achieving the goals of the VSE.I'm not meaning to suggest that companies shouldn't act to preserve their own business interest but what I am asking, is it possible to get a "fair" and open review where information isn't suppressed or disregarded because it doesn't serve the interest of a "single" more powerful constituent?
Quote from: Lobo on 01/13/2009 11:48 pmFirst: Any idea of how much it would cost to man-rate the Delta 4?Sounds like it can lift a bit more than Ares 1. But can it carry Orion and the SM dimensionally?The Delta 4 is 16.4 ft dia, and Orion is 16.5 ft. at it's widest.doesn't seem like much, but how much modification to the Delta 4 would be needed to fit the Orion?Also, I read a bit back someone asking about the insulation. Since Ares or Jupiter would be inline, is the foam neaded? And if so, could they go back to the old cheaper foam because it wouldn't matter that it sheds?Less than 500 millionDimensionally is not a problem. An adapter can be made to fit it to the D-IVAll LH2 vehicles need insulation and the current foam is the best there is. The older foam is more expensive and less efficient and also comes offSee Delta IV and Centaur
First: Any idea of how much it would cost to man-rate the Delta 4?Sounds like it can lift a bit more than Ares 1. But can it carry Orion and the SM dimensionally?The Delta 4 is 16.4 ft dia, and Orion is 16.5 ft. at it's widest.doesn't seem like much, but how much modification to the Delta 4 would be needed to fit the Orion?Also, I read a bit back someone asking about the insulation. Since Ares or Jupiter would be inline, is the foam neaded? And if so, could they go back to the old cheaper foam because it wouldn't matter that it sheds?
]Fair enough, I assume the Saturn Rockets didn't need it because it was kerosine/LO2 fueled rather than LH2/LO2 fueled?
Quote from: Lobo on 01/13/2009 10:52 pmI understand the ET won't leave LEO, but it was never designed to carry a load that would like it will be used for now.Like I said, maybe it's not a major obsticle. Just pointing out some other consideration that people might not be thinking about, especially when they all get excited about their own ideas.So you think people, which are working on DIRECT project for 2 years now, somehow "might not be thinking about" whether it is feasible of making ET-derived tank to support this weight.Surprise! They did think about it, and found out that it is possible, and not even hard.
I understand the ET won't leave LEO, but it was never designed to carry a load that would like it will be used for now.Like I said, maybe it's not a major obsticle. Just pointing out some other consideration that people might not be thinking about, especially when they all get excited about their own ideas.
Just trying to have an informative conversation, and no, I haven't been reading this forum prior to about a week ago, so I didn't have the time or energy to read through the 500 some odd pages in the first two threads in their entirety.