Rikkus67 From Canada, joined Jun 2000, 1461 posts, RR: 2 Posted (5 years 9 months 5 days 19 hours ago) and read 3907 times:
Upon viewing the latest Spacewalks by a Canadian Astronaught, and the decision by NASA to not repair the damaged heat tiles, I have a general question for everyone:
Originally, the External Fuel Tank for the space shuttle fleet was painted. NASA decided to NOT paint the fuel tank after a number of launches, sighting excesive cost and fuel burn as the primary reasons.
With the loss of one of the shuttles due to foam loss, and the continuing problems with the loss of said foam on the fuel tank during liftoff, I am wondering why NASA wouldn't consider painting the fuel tanks again? I realize the fleet only has a few years left, but I will be one of those that are going to be nervous on tomorrows re-entry.
Does anyone else share the same view on the external fuel tank? Was there as much foam loss with the fuel tank painted, or was the research into this problem only analyzed after the previous tragedy?
Cessna 172; King Air 100; Twin Otter; SAAB 340; Dash 7; Dash 8-100,-200,-300,-400; CRJ-200,700,900; ERJ-170; F-28; DC 9-
KELPkid From United States of America, joined Nov 2005, 5932 posts, RR: 4 Reply 2, posted (5 years 9 months 5 days 19 hours ago) and read 3871 times:
Weight savings. ~1100 lbs. that could otherwise go towards lifting stuff up to the ISS
Also, the first 4 or 5 flights did have the external tank painted...
The foam problems aren't really related to the paint, but rather to the foam itself: it was not a problem when the external tank contractor was using CFC's as the foaming agent. NASA made them stop using CFC's for obvious reasons...(ozone layer damage potential), and then the foam started really coming off on launch. I don't know why the foaming agent made a difference in how the external tank foam held on.
Celebrating the birth of KELPkidJR on August 5, 2009 :-)
Tugger From United States of America, joined Apr 2006, 4629 posts, RR: 7 Reply 3, posted (5 years 9 months 5 days 19 hours ago) and read 3862 times:
By eliminating the paint, NASA was able to save money and shed about 1,000 lb (455 kg) of weight, translating into improved payload performance. (from www.aerospaceweb.org)
Tug
KELPkid beat me to it!
[Edited 2007-08-21 01:39:20]
I don’t know that I am unafraid to be myself, but it is hard to be somebody else. -W. Shatner
Reins485 From United States of America, joined Jul 2005, 136 posts, RR: 0 Reply 4, posted (5 years 9 months 5 days 19 hours ago) and read 3859 times:
Weight obviously is a reason. Another reason, if they did paint it, they would not use white because spotting ice forming would be more difficult on a white surface. And another reason is if they did paint it and it chunks fell off the higher mass due to paint would lead to more damage being done to the tiles.
Quoting Rikkus67 (Thread starter): but I will be one of those that are going to be nervous on tomorrows re-entry.
There really is no reason to worry any more than usual, the shuttle has landed in the past while missing several tiles, while this is time there is only a ding and all tiles are in place. The concern NASA had with the ding is that heat gets to the frame of the shuttle and requiring extensive repair, which Endeavour has just come out of about 5 years worth of overhaul and if they couldn't use it again for a while, it would limit the amount of missions per year to the space station and maybe preventing them from completing it to its current design.
Thorny From , joined Dec 1969, posts, RR: Reply 5, posted (5 years 9 months 5 days 17 hours ago) and read 3828 times:
Quoting Rikkus67 (Thread starter): Does anyone else share the same view on the external fuel tank? Was there as much foam loss with the fuel tank painted, or was the research into this problem only analyzed after the previous tragedy?
The ground test articles and the Tanks for STS-1 and STS-2 were painted white. The paint was not applied for all tanks after STS-2's. This was primarily to save about 1,000 lbs., the weight of the paint, which is almost directly applied to the Shuttle's payload capacity. And then, as now, the Shuttle needs every pound it can shave off for payload.
There was as much foam loss on the painted Tanks as on the unpainted Tanks. Some say more, but that might only be a consequence of very early flight experience.
Painted foam is heavier than unpainted foam, so the bits that come off will have more mass and potentially will do more damage if it hits the Orbiter. Ergo, NASA still doesn't paint the Tanks.
Quoting Rikkus67 (Thread starter): but I will be one of those that are going to be nervous on tomorrows re-entry.
The Shuttles have come home with much worse before. This isn't a Columbia situation.
PC12Fan From United States of America, joined Jan 2007, 2236 posts, RR: 5 Reply 7, posted (5 years 9 months 5 days 4 hours ago) and read 3709 times:
Quoting Thorny (Reply 5): Quoting Rikkus67 (Thread starter):
but I will be one of those that are going to be nervous on tomorrows re-entry.
The Shuttles have come home with much worse before. This isn't a Columbia situation.
I still think it would have been a good idea to perform a "fix" in orbit just to see how it would do in a real test. What have you got to lose if it's been deemed safe already?
Just when I think you've said the stupidest thing ever, you keep talkin'!
Hemispheres From United States of America, joined May 2004, 85 posts, RR: 0 Reply 8, posted (5 years 9 months 5 days 2 hours ago) and read 3668 times:
Quoting PC12Fan (Reply 7): I still think it would have been a good idea to perform a "fix" in orbit just to see how it would do in a real test. What have you got to lose if it's been deemed safe already?
I don't think NASA would send someone outside the orbiter unless it is completely necessary. A lot can still go wrong on an EVA.
"I have to put in my two cents, but I only get a penny for my thoughts. - Someone is making money"
Thorny From , joined Dec 1969, posts, RR: Reply 9, posted (5 years 9 months 5 days 1 hour ago) and read 3651 times:
Quoting PC12Fan (Reply 7): I still think it would have been a good idea to perform a "fix" in orbit just to see how it would do in a real test. What have you got to lose if it's been deemed safe already?
Making it worse.
Spacewalks are always risky. Mr. Shannon said that they were looking into deliberately damaging/repairing a tile before launch to test the materials in flight conditions, possibly by STS-120 in October. That seems like a good compromise to me.
Rikkus67 From Canada, joined Jun 2000, 1461 posts, RR: 2 Reply 10, posted (5 years 9 months 5 days ago) and read 3633 times:
Thanks for the excellent feedback, everyone! The important factor that I had not contemplated was the additional mass added with the paint, defeinitely a good point. Interesting about the non-cfc issues, though.
What is the current status on the replacement vehicles for the shuttle fleet?
Cessna 172; King Air 100; Twin Otter; SAAB 340; Dash 7; Dash 8-100,-200,-300,-400; CRJ-200,700,900; ERJ-170; F-28; DC 9-
Thorny From , joined Dec 1969, posts, RR: Reply 11, posted (5 years 9 months 5 days ago) and read 3627 times:
Quoting KELPkid (Reply 2): The foam problems aren't really related to the paint, but rather to the foam itself: it was not a problem when the external tank contractor was using CFC's as the foaming agent. NASA made them stop using CFC's for obvious reasons...(ozone layer damage potential), and then the foam started really coming off on launch. I don't know why the foaming agent made a difference in how the external tank foam held on.
I didn't catch this yesterday.
It should be noted that the Tank which caused the Columbia disaster was from the pre-Non-CFC batch. The CFC issue had nothing to do with the Columbia accident. Columbia was flying the second-to-last of the older Light Weight Tanks (LWTs), whereas all the Space Station flights before Columbia and all flights since have been with the newer Super Lightweight Tank (SLWT). And only the SLWTs were using the new "green" agent.
Thorny From , joined Dec 1969, posts, RR: Reply 12, posted (5 years 9 months 5 days ago) and read 3625 times:
Quoting Rikkus67 (Reply 10): What is the current status on the replacement vehicles for the shuttle fleet?
Progressing very slowly due to lack of funding. First flight 2013. First manned flight 2014. And few are taking even those delayed dates seriously.
There are also persistent rumors that the Ares I rocket planned for the manned Orion spacecraft just won't work and that a major change is forthcoming.
Legs From Australia, joined Jun 2006, 207 posts, RR: 0 Reply 13, posted (5 years 9 months 4 days 11 hours ago) and read 3547 times:
Quoting Thorny (Reply 9): deliberately damaging/repairing a tile
On a slightly related note, what sort of temperatures does the shuttle encounter on ascent? The descent temps are more impressive, granted, but Id imagine theyd be significant on the way up as well?
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