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Post by wvengineer on Aug 29, 2022 12:07:48 GMT
Live feed of NASA's new moon rocket.
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Post by wvengineer on Aug 29, 2022 13:06:54 GMT
Launch scrubbed due to engine trouble that does not have a fast fix.
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Post by GTCGreg on Aug 29, 2022 14:05:41 GMT
Launch scrubbed due to engine trouble that does not have a fast fix. Yeah, they had some sort of fuel leak but got that resolved. This problem had something to do with preheating one of the engines. That said, this sort of thing can be expected with a new rocket design. They'll get it ironed out. |
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Post by wvengineer on Aug 29, 2022 14:52:01 GMT
Well a bit of a bummer, but defiantly better safe than sorry here. That would REALLY suck to have an accident with that thing.
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Post by the light works on Aug 29, 2022 14:52:06 GMT
nothing more annoying than finding a bug during startup.
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Post by GTCGreg on Aug 29, 2022 16:27:32 GMT
Well a bit of a bummer, but defiantly better safe than sorry here. That would REALLY suck to have an accident with that thing. Or as Musk calls it, an unplanned rapid disassembly. |
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Post by wvengineer on Aug 29, 2022 21:58:53 GMT
NASA has rescheduled for Friday, Sept 2, 2022 at noon eastern time. Here's hoping they have the hydrogen problem sorted by then.
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Post by GTCGreg on Aug 30, 2022 0:42:30 GMT
Keeping my fingers crossed.
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Post by the light works on Aug 30, 2022 4:12:40 GMT
so, in tonight's news, it sounds like they precool the engines, and the cooling system wasn't working right.
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Post by GTCGreg on Aug 30, 2022 6:49:04 GMT
so, in tonight's news, it sounds like they precool the engines, and the cooling system wasn't working right. I believe that was the original problem. The early news reports kept say they couldn't preheat the engine, but they don't preheat them, they precool them. They do this by bleeding some liquid hydrogen into the engine to cool it down before they ignite it. For some reason, they couldn't get the liquid hydrogen to bleed into the number 3 engine (there's 4.) Right now, if they can get the precooling problem solved, they are going to try for this Friday, but the weather isn't looking too good. If that fails, they are shooting for a 1.5 hour window on Monday, Sept 5th. And if that doesn't happen, they have to wait until Sept 19th. |
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Post by rmc on Aug 30, 2022 9:58:48 GMT
My "negative" outlook on the SLS design.
Space Shuttle had foam on the main tank that could, and would, break off and potentially damage stuff.
Space Shuttle had o-rings on SRBs that were susceptible to failing (too cold? No proper fit... who knows? Bump it the right way and maybe no proper fit too when under a lot of fiery pressure. And, yes. I know these were redesigned)
Understandably it's a stretch, but foam falling, striking an SRB and loosening an o-ring fit SEEMS within the realm of possibility. And, yes, As I stated, I know the o-ring fittings were all redesigned after the 1986 incident.
But, it seems like to me they took the most dangerous rocket ever made for "shuttling" people, and borrowed the very worst parts of its configuration with which to reconstruct a reborn version... albeit this time, at least, there is a pretty good escape rocket atop it all.
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Post by wvengineer on Aug 30, 2022 12:40:58 GMT
For the SRB boosters, the o-ring problem was due to poor seal design and poor choice of o-ring material that reacted poorly to cold temps. The seal has been redesigned and they use different rubber in the o-rings now. They now test these boosters in much worse conditions than the Challenger accident and have performed flawlessly. Since the Challenger redesign, the SRBS have proven to be one of the most reliable boosters made. As far as foam goes, as far as I know, shedding foam is still a problem, but now you don't have a fragile space place strapped to the side. So if you loose foam, it doesn't matter because there is nothing there to hit. So in both cases, I would argue that those issues are not concerns in this configuration. It is interesting to go through the accident investigations for both the Challenger and Columbia and the root cause in both cases was NASA management ignoring the advice of engineers and pushing ahead with aggressive flight schedules even though they knew of problems. Also the same root cause for Apollo 1 as well. There is a documentary on NetFlix called "Challenger: The Final Flight" that looks at the engineering and management behind both accidents. Highly recommended. en.wikipedia.org/wiki/Challenger:_The_Final_FlightSo the question here is did NASA management learn from their previous experience and listen to the engineers or just let "Go fever" push ahead. Here's hoping that they are playing safe. |
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Post by the light works on Aug 30, 2022 14:06:03 GMT
I don't recall if I said it about challenger, but after the columbia disaster, I recognized that there is a trend at NASA to start out cautiously, and make sure everything is 100% perfect, and then as things don't go wrong, they start getting more and more relaxed about safety precautions, until it bites them in the arse. then they co back to being neurotic about caution.
an engineering youtuber pointed out it is possible for a circle to be deformed in such a way that it still appears round in a caliper test. he mentioned there was a possibility the SRB assemblies might have had something like that, which helped cause the o-ring failure. I think an in depth study would show that the foam shedding issue got worse over time*, and wasn't so severe at the time of the challenger disaster, not to mention the SRBs not having any heat shielding, let alone the delicate heat shielding used on the shuttle, and so weren't affected by foam strikes.
*by which I mean NASA started out investing more into preventing significant foam shedding, and when there weren't any major problems, gradually got less and less careful to control it
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Post by GTCGreg on Aug 30, 2022 15:11:48 GMT
But in this case, it’s a little more cut and dry. The problem has nothing to do with SRB’s or foam. It also has little to do with NASA either being overlyl cautious or underly so. It has to do with the thing is broke so no, you can’t light it.
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Post by rmc on Aug 30, 2022 15:44:18 GMT
I know I wouldn't want blocks of foam at high velocity raining down on the aft skirt feed thru (Rooster Tail) of an SRB. Who knows if the five segment joints, above, can take being torqued out of alignment, when under burning pressure.
But, anyway.
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Post by the light works on Aug 30, 2022 16:06:00 GMT
But in this case, it’s a little more cut and dry. The problem has nothing to do with SRB’s or foam. It also has little to do with NASA either being overlyl cautious or underly so. It has to do with the thing is broke so no, you can’t light it. yeah, in this case a thing in the startup checklist didn't happen, so the checklist had to be stopped. by point was that (and it is human nature for anything, not just space launches) changes were made in how things were done. as things went well, changes were made to reduce weight and improve performance, and operators became more confident that everything would go right. I recall that in the case of the challenger explosion, the original launch protocols would have scrubbed the launch because of the cold. |
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Post by GTCGreg on Aug 30, 2022 16:30:57 GMT
But in this case, it’s a little more cut and dry. The problem has nothing to do with SRB’s or foam. It also has little to do with NASA either being overlyl cautious or underly so. It has to do with the thing is broke so no, you can’t light it. yeah, in this case a thing in the startup checklist didn't happen, so the checklist had to be stopped. by point was that (and it is human nature for anything, not just space launches) changes were made in how things were done. as things went well, changes were made to reduce weight and improve performance, and operators became more confident that everything would go right. I recall that in the case of the challenger explosion, the original launch protocols would have scrubbed the launch because of the cold. Sorry, I didn’t mean to imply that you were wrong. In fact, I fully agree with what you’re saying. |
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Post by the light works on Aug 30, 2022 16:49:00 GMT
yeah, in this case a thing in the startup checklist didn't happen, so the checklist had to be stopped. by point was that (and it is human nature for anything, not just space launches) changes were made in how things were done. as things went well, changes were made to reduce weight and improve performance, and operators became more confident that everything would go right. I recall that in the case of the challenger explosion, the original launch protocols would have scrubbed the launch because of the cold. Sorry, I didn’t mean to imply that you were wrong. In fact, I fully agree with what you’re saying. hopefully they will never become incautious to the point of ignoring a malfunction. |
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Post by wvengineer on Aug 30, 2022 19:35:45 GMT
But in this case, it’s a little more cut and dry. The problem has nothing to do with SRB’s or foam. It also has little to do with NASA either being overlyl cautious or underly so. It has to do with the thing is broke so no, you can’t light it. yeah, in this case a thing in the startup checklist didn't happen, so the checklist had to be stopped. by point was that (and it is human nature for anything, not just space launches) changes were made in how things were done. as things went well, changes were made to reduce weight and improve performance, and operators became more confident that everything would go right. I recall that in the case of the challenger explosion, the original launch protocols would have scrubbed the launch because of the cold. In the case of Challaner, Engineers at the company who made the boosters said DO NOT LAUNCH. The problem was a known issue and while a fix was in the works, NASA management was pushing to go ahead anyway. NASA was pushing to get flights more often to justify the cost of the shuttle program. With this flight, because it was a media event with Christa McAuliffe going up, NASA strong-armed the SRB supplier to sign off on the flight over the major objection of the engineers. The media embarrassment of a delay was more important to them than the safety of a known problem. The foam was an interesting one. Foam strikes were a known problem from the very first flight. The first flight after the Challenger disaster had enough damage to the Atlantis, and the crew knew about the damage, that the crew was fulling expecting NOT to survive the re-entry. By some miracle, the damage was not in as critical location and they survived. After that, NASA just got the idea that "It's no big deal." In the 2000's, NASA was pushing more flights to finish the ISS and again, ignored engineer concerns about damage from foam. IN both cases, NASA management was more concerned about media appearance and pushing stuff to fly than listening to the engineers involved. |
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Post by the light works on Aug 30, 2022 20:07:51 GMT
yeah, in this case a thing in the startup checklist didn't happen, so the checklist had to be stopped. by point was that (and it is human nature for anything, not just space launches) changes were made in how things were done. as things went well, changes were made to reduce weight and improve performance, and operators became more confident that everything would go right. I recall that in the case of the challenger explosion, the original launch protocols would have scrubbed the launch because of the cold. In the case of Challaner, Engineers at the company who made the boosters said DO NOT LAUNCH. The problem was a known issue and while a fix was in the works, NASA management was pushing to go ahead anyway. NASA was pushing to get flights more often to justify the cost of the shuttle program. With this flight, because it was a media event with Christa McAuliffe going up, NASA strong-armed the SRB supplier to sign off on the flight over the major objection of the engineers. The media embarrassment of a delay was more important to them than the safety of a known problem. The foam was an interesting one. Foam strikes were a known problem from the very first flight. The first flight after the Challenger disaster had enough damage to the Atlantis, and the crew knew about the damage, that the crew was fulling expecting NOT to survive the re-entry. By some miracle, the damage was not in as critical location and they survived. After that, NASA just got the idea that "It's no big deal." In the 2000's, NASA was pushing more flights to finish the ISS and again, ignored engineer concerns about damage from foam. IN both cases, NASA management was more concerned about media appearance and pushing stuff to fly than listening to the engineers involved. it's that whole "it's worked just fine so far" attitude we all get. |
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