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NASA Astronaut on Columbia Repair (and others)
"Pat Flannery" wrote I think the odds of this working are about 1% at best. It still doesn't address the problem of what the EVAing astronauts are supposed to hold onto while they are putting stuff into the hole, .... Actually that was the least of their problems -- they would be holding onto the PLB door, the centerline edge of which would have been positioned within a few feet of the damaged RCC area. They could have rigged a workable foot restraint attached to handholds along that edge. |
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NASA Astronaut on Columbia Repair (and others)
"Pat Flannery" wrote in message ... Had there been warning, you also bet that there wouldn't have been anybody in the ship doing entry without helmets and gloves -- an appalling failure of safety practices, in real life, but sadly consistent with safety standards that had crept up on some (not all, or even most) of the team. Yeah, that was a real sloppy thing to do. They were getting very lax about things, and Story Musgrave's standing reentry really set a bad example in that regard. the thing that still galls me about that particular Musgrave Maneuver is that, the evening of the Columbia disaster, he was on CNN *bragging* about doing that entry, going on and on about all the neat stuff he saw out the window. At some point he must have seen Miles's face, or he just suddenly realized what he was saying, because he got very serious all of a sudden, and they cut to somebody else. Trauma makes people do and say some very unfortunate things. -- Terrell Miller "Just...take...the...****ing...flower...darlin g" Terrell's dating style according to OKCupid.com |
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NASA Astronaut on Columbia Repair (and others)
"Jorge R. Frank" wrote in message ... Normally, the boundary layer trips to turbulent well after the period of peak heating but rough surfaces can result in early transitions. A transition prior to Mach 21 can cause vehicle damage and a transition prior to Mach 24 can cause loss of vehicle. The improvised Columbia repair would likely have gone turbulent right from the beginning of entry (Mach 25), exposing the RCC panel and the trailing black tiles to the superheated air. Columbia's damage occurred at just about the worst possible location since the shock from the nose cap intersects the shock from the leading edge between RCC panels 5 and 13, depending on Mach number. That's what some of these boneheads don't understand- you can't just use a spatula and smooth it by eye. It has to be smooth to an extremely fine degree to hold off (not prevent) boundary layer separation. I'm afraid it's not something that Real Men (tm) are going to be able to do off the cuff hanging on the end of a robot arm. |
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NASA Astronaut on Columbia Repair (and others)
Scott Hedrick wrote:
That's what some of these boneheads don't understand- you can't just use a spatula and smooth it by eye. It has to be smooth to an extremely fine degree to hold off (not prevent) boundary layer separation. Separation or transition? Lee Jay |
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NASA Astronaut on Columbia Repair (and others)
Pat Flannery wrote:
I think the odds of this working are about 1% at best. It still doesn't address the problem of what the EVAing astronauts are supposed to hold onto while they are putting stuff into the hole, or the fact that bags of water will boil and explode as soon as they get depressurized in the airlock, or water coming out of some sort of jury-rigged hose is going to emerge as a spray of superfine droplets, not come out as a stream that will flow into the hole. You might be able to get the hole filled in with the hose, but it would be anything but smooth, and you'd have chunks of ice around it that would break free and do more damage as heating started on reentry. Not to mention the fact that after you overcome all _those_ difficulties - you have to deal with two different (additional) problems; 1 - hoping the steam from the vaporizing ice doesn't damage your patch 2 - your patch will also be under attack from behind as the temperature in the wing goes above freezing. D. -- Touch-twice life. Eat. Drink. Laugh. -Resolved: To be more temperate in my postings. Oct 5th, 2004 JDL |
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NASA Astronaut on Columbia Repair (and others)
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NASA Astronaut on Columbia Repair (and others)
Herb Schaltegger wrote: That's not a real URL, Patrick. No booze for you! Yeah, realized that and went to the page it was on instead. :-) Pat |
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NASA Astronaut on Columbia Repair (and others)
Personally, I from what I've read in the CAIB, it doesn't look to me that
NASA seriously looked at the repair option before putting out the report. Bags of water and tools, when they had all sorts of thermal blankets, some graphite composites, and who knows what else. Having never seriously looked at the repair option, it's no wonder NASA is has so much trouble trying to figure out how to actually do a premission planned repair. Really makes me wonder if the attitude at NASA went from "There is nothing we can do, so why look" to "There is nothing we could have done anyway, we did the right thing". Columbia sometimes it tripped the boundary layer quite early, Mach 19. ....Normally, the transition from smooth to turbulent flow occurs equally on both wings after the orbiter has slowed to about Mach 8. On some missions, however, the transition has happened when the shuttle is higher, in the hottest part of re-entry, moving as fast as Mach 19... http://www.floridatoday.com/columbia...ry2A44731A.htm "This is magnified when transition occurs early, which has resulted in slumped tiles and other damage to the shuttle (tiles). The higher heating has also aggravated the effect of ascent debris impacts." Also, you have no idea if an improvised Columbia repair would or would not have trip the boundary layer. Or, even if it was tripped what damage would occur, other than a bunch of slumped tiles and possibly an overheated unusable Vehicle sitting on the runway. Your statement about Mach 24-25 being some sort of limit makes no sense at all. From EI to Mach 25, temperatures may be high, but density is very low. Dynamic pressure is below 20 psf, and stagnation heat flux is still building up to this point. It's not the high heating region. Page 63, 64 http://caib.nasa.gov/events/public_h...8/present.html Anybody have a good URL to all the Columbia Repair Studies? How many different patches were studied? What materials were used in the patches? Did they have the spacewalk consumables? How did all the candidate repair materials do in the arc jet facility? Where are the studies? Where are the test/experimental results? How did the thermal blankets perform on the leading edge? Did they melt and flow smooth? Did the high spot disappear first? What Mach Number? How did the glass/water composites perform? Would a Thanksgiving Turkey have worked better? In figuring out how to patch some future Orbiter, figuring out how to patch Columbia wouldn't have been a total waste of time. -- Craig Fink Courtesy E-Mail Welcome @ -- On Tue, 14 Nov 2006 23:44:46-0500, Scott Hedrick wrote: "Jorge R. Frank" wrote in message ... Normally, the boundary layer trips to turbulent well after the period of peak heating but rough surfaces can result in early transitions. A transition prior to Mach 21 can cause vehicle damage and a transition prior to Mach 24 can cause loss of vehicle. The improvised Columbia repair would likely have gone turbulent right from the beginning of entry (Mach 25), exposing the RCC panel and the trailing black tiles to the superheated air. Columbia's damage occurred at just about the worst possible location since the shock from the nose cap intersects the shock from the leading edge between RCC panels 5 and 13, depending on Mach number. |
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NASA Astronaut on Columbia Repair (and others)
Remember the question why NASA did not release their results on the in orbit repair options for Columbia? Incorrect. The results were released with the CAIB report, both as a chapter in the main report and as an appendix. The only "results" they released was a statement that their tests were inconclusive. No report what they tested, how they tested neither the results they got. They did no materials testing, only analysis, and very limited analysis at that. They didn't just say the analysis was inconclusive. They said more than that. "The assessment of the level of difficulty of the repair operation is high. The level of risk to the crew is moderate and the risk of doing additional damage to the Orbiter is high (i.e. enlarging the wing leading edge breach). The overall assessment of the expectation of task success is moderate to low, depending on damage site characteristics and the required repair technique." "The results while inconclusive, do not indicate this option was likely to succeed." Actually, what you cite above is a report by a NASA team. It was published by the CAIB but the CAIB was not involved in its writing. The CAIB conclusion on the subject did not oppose it because they had no other data then the NASA report to base on: "Because the NASA team could not verify that the repairs would survive even a modified re-entry, the rescue option had a considerably higher chance of bringing Columbia's crew back alive." (CAIB Vol. 1) In effect, the same guys who immediately after the diasater openly stated "there was no way to repair" (they even said it that line as the astronauts were still alive) did later the task to investigate whether their statement was correct. They did it the NASA disaster way: "inconclusive" It seems the results were too unwanted obvious: Gutierrez is wrong. And it turns out, so were NASA's results from the CAIB report. The three years of work that have gone into RCC repair capability since that report have made clear that the in-flight repair options for Columbia would not have worked. What is your source? Was it you who said something the same line over a year ago claiming some knowledge of NASA tests not yet released? As we got no source it was dismissed as one of the many Columbia Usenet myths. But maybe there is a report out now. I`m not the only one eager to read it! It depends on what you mean by "report". NASA has published no report directly addressing Columbia repair on STS-107. But then again, that's not necessary. What I did was to read the CAIB report, both Volume 1 section 6.4 and Appendix D.13, and make careful note of the assumptions both stated and implicit. Then I read on NASA's work on RCC repair and entry aerothermodynamics since the CAIB report was published. This work does not directly address 107, but the results of it invalidate the assumptions from CAIB. It's as simple as that. First, the results of the RCC impact tests at SwRI demonstrate that the area around the hole in panel 8L almost certainly had surrounding areas where the RCC was cracked and delaminated. Arcjet tests at Ames and JSC demonstrate that RCC damage propagates rapidly along these cracks. So it doesn't matter what the crew puts in the hole behind the panel to try to stop the flow of superheated air; the damage will quickly spread and allow the superheated air to simply go around the repair. In simple words you assume the hole in the RCC would grow up until most the RCC was consumed and the ice block was no longer a blockade. That would be a clear "no way to repair". But I doubt that the delamination would spread that fast. Its a plasma oxidation of an otherwise covered RCC layer on the open crack surface. The hole may be 2 cm wider after reentry, but not 4 times its size. As you read it otherwise somewhere (or you got that impression there), please give me your source. Second, due to the improvised materials, the repair would not have been smooth enough to prevent an early boundary layer transition. RCC is rated to 3000 deg F, the lower surface black tiles to 2200 deg F. The shock ahead of the vehicle contains superheated air at temperatures up to 10,000 deg F. It is the laminar (smooth) boundary layer that protects the TPS from these extreme temperatures. Normally, the boundary layer trips to turbulent well after the period of peak heating but rough surfaces can result in early transitions. A transition prior to Mach 21 can cause vehicle damage and a transition prior to Mach 24 can cause loss of vehicle. The improvised Columbia repair would likely have gone turbulent right from the beginning of entry (Mach 25), exposing the RCC panel and the trailing black tiles to the superheated air. Columbia's damage occurred at just about the worst possible location since the shock from the nose cap intersects the shock from the leading edge between RCC panels 5 and 13, depending on Mach number. We had this issue here before, maybe not with you. Just summ: 1. the hole it had is a larger BL obstacle then any remaining irregularities from an repair 2. there was no evidence of BL trip related damage by CAIB, it all developed at the RCC 3. required smoothness criteria for the shuttle was to protect it against any thermal damage to the tiles. This was to keep the tiles reusable. In case of an emergency some tile damage would be accecptable. 4. on other missions Columbia had several early BL trips without serious damage or without any damage at all. -- JRF ## CrossPoint v3.12d R ## |
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NASA Astronaut on Columbia Repair (and others)
The Guy In Ireland wrote:
"Story Musgrave's standing reentry really set a bad example in that regard. " Sorry whats that all about? Did he stand for a reentry and why did he? From http://www.spacestory.com/flyingdr.htm : "I was conducting my own experiment. The whole flight had been so totally exhilarating and I was on such a high that I decided to stand throughout re-entry. It's my nature to press and push, to go beyond what's expected. I had my Hasselblad camera and I was taking some photos. Also, I wanted to prove that you can stand while going from zero gravity back into gravity. That's important if an astronaut ever has to leave the top deck and go below to throw a switch or circuit breaker. I wanted to show that the cardiovascular system doesn't have any problem going back into gravity and that you don't have to be strapped down." "My standing was smooth and steady, and it shows how the STS system is maturing. We all had total confidence. Standing up throughout re-entry, instead of being strapped down, was the perfect end to a perfect trip. I was having fun, as always. " -- Something like: "ntlworld" "com" "dot" "at" "marypegg" |
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