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#41
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Ladies and Gentlemen of the 51-L Jury
Alasdair McKie
Is your pursuit of the valve command info tied completely to the crossfeed issue you know existed or does it relate to something else? J Maxson Both, obviously. heh heh.....the jury is back. They found Maxson insane, but set the penalty at hanging. |
#42
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Ladies and Gentlemen of the 51-L Jury
In article , "John Maxson"
wrote: Do you have nothing better to do than insult my intelligence? I'm sorry that you feel I'm wasting your time. I've seen a lot of really hostile language lobbed in your direction during the time that I've been reading this group, and I've often wondered which came first - their hostility or yours. In retrospect, I can honestly say to myself that I haven't done anything to deserve this kind of response. I can't help but feel that if you don't have the time for me, I don't have the time for you. While I truly feel you are pursuing your investigation of the events surrounding the loss of Challenger because you want to know the truth and you want the world to know the truth, I'm sorry to say you're closing another mind to your ideas. -A -- Remove .kil to reply by email. |
#43
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Berndt's Bias
Alasdair McKie wrote in message
... In article , "John Maxson" There is a document linked from that post (http://history.nasa.gov/rogersrep/v5p1227.htm) which also depicts a chart showing Findings next to the item "RCS" as "Nominal" How did you miss the column 'EVALUATION,' where it lists "All Measurements Except Valve Commands?" -- John Thomas Maxson, Retired Engineer (Aerospace) Author, The Betrayal of Mission 51-L (www.mission51l.com) |
#44
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Ladies and Gentlemen of the 51-L Jury
In article , Jon Berndt wrote:
"Stephen Stocker" wrote in message In article , Chuck Stewart The correct phrasing would seem to be "Would it have been possible? And, if so, under what circumstances would it have been possible?" Yep, at least on the first part. Under what circumstances would be my next question. If I understand what I've read, while it's not normal for such an event to occur, it *is* within the realm of possibility, with any one of several sets of circumstances? Steve The question of whether or not the RCS could *possibly* be fired during first stage when no abort has been declared should be an easy one to answer. Here is what can be said based on information I have on hand at home: 1) The RCS training manual that is used by flight crews, instructors, and flight controllers (publication RCS 2102 April 1987) states specifically that the RCS is used for on-orbit manuevers, entry flight control, and during ascent in "off-nominal situations" (engine failure aborts) for augmented roll control (this includes the SERC capability mentioned by Jorge previously). It categorically states that the vernier jets (the smaller jets) are only used on-orbit for fine attitude control). This detailed 100+ page training manual states when the RCS is used. First stage usage when no abort has been declared is NOT one of the situations in which the RCS is said to be used. If there was a situation where RCS jets could be used during nominal first stage, this manual would very likely state such. OK. One minor issue which comes to mind is whether the manual cited differs in any significant respect from the one used at the time of the Challenger loss? A couple of other things are running around in my head (extra space ), but they're sort of irrelevant in view of the next two paragraphs... 2) The Ascent Guidance and Control manual (ASC G&C 2102) shows control diagrams for nominal first stage flight. The outputs of the flight control diagrams are to the SRB gimbal actuators and to the main engine gimbal actuators. The RCS jets are not in the loop. A full description of RCS jet usage for abort situations is given. If RCS jets were used in nominal first stage, the document would very likely state such. 3) No purpose would be served by having RCS jets fire for control purposes in nominal first stage flight. In fact, it's a ludicrous idea. Firing an RCS aft yaw jet provides about 870 lbs thrust (vacuum), and provides a very small rolling moment about the center of gravity of the stack. The same effect can be achieved by gimballing nozzles on the ~2.5 million lb thrust SRBs by 0.01 degrees. Really. Do you see what I am getting at? Yes, and it probably would've been my *next* question. Whew, rereading these figures. Sounds like pitting a car engine against a sewing machine motor, only more so. 4) All of us here who have experience with the shuttle program and have been immersed in it for years aren't simply barking out our asses when we say that the RCS jets would not have been commanded to fire during first stage flight when all the engines were still working and no aborts had been declared. Can we point to a document that comes out and says specifically "The RCS jets do not - and in fact are incapable of - firing during first stage"? I cannot find one, but I do not expect to find one, because it is accepted and understood that they do not. I missed this when I first scanned through it. It touches on the other point which I still couldn't pin down, which basically goes back to the question of possibilities. 5) Regarding the recent JTM statement: "That's one of the first things I verified on my job in the days following the disaster." I'm not sure how to take that statement. Are we supposed to believe that John Maxson personally verified that the software that was loaded in the GPCs on Challenger's last flight specifically included code that fired the RCS jets (for God-knows-what reason)? In light of what I know and what others have posted, and given the kind of "proof" that I have seen in his book personally, I have only one thing to say: prove it. That was my *assumption* of what John meant, at least that the software loaded was capable of firing them. But as someone pointed out, that's all it is, *my* assumption. Whatever the case, it's interesting to me, and I appreciate the time taken by all to make this understandable to me. As I may have said in another post, I think maybe it's easier for somebody like me, on the "outside" from a technical standpoint, to really enjoy this type of debate. 6) The video/film clip from which the 51l images on the main page of www.mission51l.com are taken from show an artifact that is visible in two camera views and appears to emanate from the "top" SSME. This artifact is not present in more obvious views from north located cameras. I have located a volunteer who has agreed to host about 100 MB of .avi files of 51L footage, within days, I hope. You will be able to judge for yourself. Sounds great! The only video I've been able to find is fairly low resolution and I'm the first to admit that my perception of images isn't the greatest in the world. Also, I wrote last week about inadvertent RCS firings and relayed that I would provide the reference. So, here it is: --- "Space Shuttle Avionics System", NASA SP-504, John F. Hanaway, Intermetrics, Robert W. Moorehead, NASA HQ, 1989 pg. 44: "If a thruster fires because of an incorrect command from one of the GPC's or because of some other failure in a string, an opposing thruster or thrusters controlled by other computers in the set will be commanded to fire to counteract the erroneous torque on the vehicle. An appropriate alarm will be sounded and the crew will be required to take appropriate manual action to disable the uncontrolled jet before fuel use or other constraints are violated." ... "Misfiring RCS jets are detected by sensing the chamber pressure in the jet each time it is commanded to fire, with an appropriate delay to account for the pressure buildup. Continuously firing (failed on) jets are detected by comparing the state of the computer command to a given jet with the voltage applied to the solenoid drivers, which activate the fuel and oxidizer valves causing the jet to fire. If the solenoid driver voltage indicates that the jet is firing with no associated computer command, the jet is declared failed on, the crew is notified, and the associated propellant manifolds must be closed to prevent loss of fuel." Finally, an area where I feel on solid ground! At least the principle of it. The relative simplicity and elegance of things like that amazes me. Multiply it by what, 100,000 or so, and you have the electrical system of a shuttle? g So, I am trying to pass along what several others have been helping with: no RCS jets are believed to be commanded during nominal first stage, [extremely unlikely] inadvertent firings would be handled by the flight software and/or the crew, telemetry would show positive signs, etc. There is no proof I am aware of that the RCS jets could fire during nominal first stage flight for 51l, nor is there visual evidence they did, nor have we seen telemetry evidence that there was. And this, I think, is the only real issue of debate related to the RCS? It helps me in more ways than one, as did your web site. I didn't feel that it told me what I was seeing or not seeing, but rather gave me a groundwork from which to start. Whether that was your intention or not, I think it's a positive thing. Argh, sorry about the short soapbox, and thanks again. Steve Jon |
#45
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Ladies and Gentlemen of the 51-L Jury
In article , John Maxson wrote:
Stephen Stocker wrote in message ... In article , Jon Berndt wrote: Can we point to a document that comes out and says specifically "The RCS jets do not - and in fact are incapable of - firing during first stage"? I cannot find one, snip It touches on the other point which I still couldn't pin down, which basically goes back to the question of possibilities. snip Are we supposed to believe that John Maxson personally verified that the software that was loaded in the GPCs on Challenger's last flight specifically included code that fired the RCS jets (for God-knows-what reason)? In light of what I know and what others have posted, and given the kind of "proof" that I have seen in his book personally, I have only one thing to say: prove it. snip That was my *assumption* of what John meant, at least that the software loaded was capable of firing them. snip There is no proof I am aware of that the RCS jets could fire during nominal first stage flight for 51l, nor is there visual evidence they did, nor have we seen telemetry evidence that there was. Can you make the same statement if you remove the word "nominal?" And this, I think, is the only real issue of debate related to the RCS? There is no "issue of debate" with me over any "nominal" 51-L ascent, nor over any of the flights beyond Mission 51-L. The officials who launched 51-L waivered at length over the unusual hazards involved. OK. I *think* I'm still on the right track, even though the only thing I can do is ask questions and try to learn something. Pages 31-32 and 46-47 of my book (over which Berndt is in denial) tell some of "the rest of the story" (as Paul Harvey would say), and I have good reason to believe that anyone except someone as biased as Berndt would find it extremely compelling. I believe that everybody who knows the technical aspects of the shuttle would have to be "biased", in the sense of having their own opinions based on their experiences. Maybe I'm weird, but I also think it can lead to quality debate, and I hope that's where this is leading. I do not intend to post all of that on USENET, however. Let me just say that KSC made more last-minute changes to the 51-L flight software load than for any prior mission, many without verification and proper sign-off. There were many verbal waivers. I'll quote from page 31: "Johnson waived a requirement to downlink the RCS data, and an unusual Lockheed uplink accomplished the change." Now whether that extended to the switch-scan data, I'm not positive; but sources whom I trust felt very strongly that it should not have. That probably answered Jon's question, if I understood it correctly. (Please correct me if I'm wrong, my brain's tired!) And again, I appreciate the information from both of you. Steve |
#46
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Ladies and Gentlemen of the 51-L Jury
Stephen Stocker wrote in message
... In article , John Maxson wrote: Pages 31-32 and 46-47 of my book (over which Berndt is in denial) tell some of "the rest of the story" (as Paul Harvey would say), and I have good reason to believe that anyone except someone as biased as Berndt would find it extremely compelling. I believe that everybody who knows the technical aspects of the shuttle would have to be "biased", in the sense of having their own opinions based on their experiences. Maybe I'm weird, but I also think it can lead to quality debate, and I hope that's where this is leading. Let's hope so. If they let post-51-L spin get in the way of finding out what happened on 51-L, they are being subjective, not objective. Since my most severely critical opposition is coming from folks with post-51-L experience at JSC, one would think they would be objective enough to obtain the waiver log and the waivers for 51-L as a starting point for their understanding and argument of flight software issues. I don't see that happening. They stonewall by putting up strawmen. -- John Thomas Maxson, Retired Engineer (Aerospace) Author, The Betrayal of Mission 51-L (www.mission51l.com) |
#47
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Ladies and Gentlemen of the 51-L Jury
Stephen Stocker wrote in message
... In article , John Maxson wrote: There were many verbal waivers. I'll quote from page 31: "Johnson waived a requirement to downlink the RCS data, and an unusual Lockheed uplink accomplished the change." Now whether that extended to the switch-scan data, I'm not positive; but sources whom I trust felt very strongly that it should not have. That probably answered Jon's question, if I understood it correctly. (Please correct me if I'm wrong, my brain's tired!) I don't know what his question was, so I'll confess that I can't. I feel quite strongly that nothing will change his opinions/attacks. I will say this, though. I don't trust any RCS telemetry from JSC as being representative of what happened during Mission 51-L. It's essentially worthless, being atmospheric pressure with KSC readings in the operating range zeroed out except at the very end. My 51-L RCS telemetry from KSC has values in the operating range, one at a time not inconsistent with a plot in the PC Report. Nevertheless, the 51-L House S&T technical staff was unable to get 51-L RCS T/M from NASA Headquarters to confirm that RCS firings occurred during Mission 51-L, so it was left *open*. -- John Thomas Maxson, Retired Engineer (Aerospace) Author, The Betrayal of Mission 51-L (www.mission51l.com) |
#48
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Berndt's Bias
"John Maxson" wrote in message news:bhkskr$1c2 How did you miss the column 'EVALUATION,' where it lists "All Measurements Except Valve Commands?" If the chamber pressures and temperature readings, and firing commands (as opposed to valve commands) show no RCS action, that's pretty unequivocal. NO RCS FIRINGS OCCURRED. |
#49
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Oberg Seeks Technical Explanation
"Jon Berndt" wrote in message news:3f3db788$0$64929 FWIW, I have actually seen TAL in some NASA docs as Trans-Atlantic Landing, although now everyone seems careful about calling it Transoceanic Abort Landing. True, some NASA people are human, but then how does that explain the TAL abort from Vandenberg that we designed, into Easter Island or Hao? |
#50
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Ladies and Gentlemen of the 51-L Jury
"John Maxson" wrote in message I will say this, though. I don't trust any RCS telemetry from JSC as being representative of what happened during Mission 51-L. It's essentially worthless, being atmospheric pressure with KSC readings in the operating range zeroed out except at the very end. My 51-L RCS telemetry from KSC has values in the operating range, one at a time not inconsistent with a plot in the PC Report. Nevertheless, the 51-L House S&T technical staff was unable to get 51-L RCS T/M from NASA Headquarters to confirm that RCS firings occurred during Mission 51-L, so it was left *open*. This is a claim that is subject to rational documentation and proof. Please show us your 51-L RCS telemetry records. On what basis do you aver -- and what significance to you suggest -- that some capitol hill staffer couldn't get some sort of document from HQ, when actually the document would have come from JSC? And is "open" a status flag in a published report, or is that more just verbal memory? |
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