Author Topic: Protecting SLS from Fire and Ice - TPS foam application proceeding at Michoud  (Read 10320 times)

Offline MaxTeranous

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I do get that the spray foam insulation is needed for SLS in it's current guise, it just this (excellent) article makes it feel like it takes a lot of time and effort (and thus money) due to design decisions and requirements when compared to other rockets. Falcon was used as a comparison earlier in the thread, and as stated that has insulation too, but LH2 (rather than RP-1) requires way more insulation, and the need to sit fully fueled for 4 hours (rather than "easy" and quick RP-1 tanking and detanking) as a requirement that also leads to even more insulation. Add them together and the $$$$ looks to skyrocket in comparison. Is the cost breakdown of all the insulation for each SLS rocket known?

Online envy887

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I do get that the spray foam insulation is needed for SLS in it's current guise, it just this (excellent) article makes it feel like it takes a lot of time and effort (and thus money) due to design decisions and requirements when compared to other rockets. Falcon was used as a comparison earlier in the thread, and as stated that has insulation too, but LH2 (rather than RP-1) requires way more insulation, and the need to sit fully fueled for 4 hours (rather than "easy" and quick RP-1 tanking and detanking) as a requirement that also leads to even more insulation. Add them together and the $$$$ looks to skyrocket in comparison. Is the cost breakdown of all the insulation for each SLS rocket known?

Sitting for 4 hours isn't the issue. They have to top the tanks anyway, and could easily just pour more fuel in. LH2 tanks need insulation because they otherwise will condense liquid air, which is a massive heat sink into the tank, and also a fire hazard due to the high LOX content.

I would be interested in a detailed explanation of why some vehicles use external insulation on LOX tanks and non-tank surfaces, while others do not.

Offline Steven Pietrobon

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On Ariane V, they use 2 cm thick insulating tiles made from expanded polyurethane.

http://www.sciencephoto.com/media/87848/view
Akin's Laws of Spacecraft Design #1:  Engineering is done with numbers.  Analysis without numbers is only an opinion.

Offline eeergo

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On Ariane V, they use 2 cm thick insulating tiles made from expanded polyurethane.

http://www.sciencephoto.com/media/87848/view

Thank you for that, I had long searched for a good explanation or picture of what Ariane 5 used for TPS (especially how it compared to the Shuttle's ET, when particle release was a concern for STS - I still wonder how it compares).
-DaviD-

Online DaveS

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On Ariane V, they use 2 cm thick insulating tiles made from expanded polyurethane.

http://www.sciencephoto.com/media/87848/view

Thank you for that, I had long searched for a good explanation or picture of what Ariane 5 used for TPS (especially how it compared to the Shuttle's ET, when particle release was a concern for STS - I still wonder how it compares).
Ariane V doesn't have any debris concerns with the insulation as it doesn't have an orbiter hanging off it that has a fragile TPS. So that was something unique to the shuttle.
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Offline woods170

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On Ariane V, they use 2 cm thick insulating tiles made from expanded polyurethane.

http://www.sciencephoto.com/media/87848/view
Yes, and ESA and it's contractors are slowly moving away from it. For Ariane 6 they are shifting to spray-on PU foam for the upper stage. If and when proven successful the plan is to implement spray-on foam on the main stage of A6 as well. But the initial vehicles will still fly with insulation tiles similar to the ones used on A5.

The expanded PU tiles on A5 are a carry-over from the tiles used on the H8 and H10 stages of Ariane 1, 2, 3 and 4.

Offline eeergo

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On Ariane V, they use 2 cm thick insulating tiles made from expanded polyurethane.

http://www.sciencephoto.com/media/87848/view

Thank you for that, I had long searched for a good explanation or picture of what Ariane 5 used for TPS (especially how it compared to the Shuttle's ET, when particle release was a concern for STS - I still wonder how it compares).
Ariane V doesn't have any debris concerns with the insulation as it doesn't have an orbiter hanging off it that has a fragile TPS. So that was something unique to the shuttle.

Obviously :) But there must exist some level of knowledge, if perhaps not as detailed as STS with its cameras and cryopumping studies. Large TPS shedding might be damaging to other LV parts as well (see STS-112)
-DaviD-

Offline Lars-J

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If you are listing alternatives insulation strategies, why not use the most successful hydrogen stage of all time? (I believe) - Centaur.

Offline woods170

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On Ariane V, they use 2 cm thick insulating tiles made from expanded polyurethane.

http://www.sciencephoto.com/media/87848/view

Thank you for that, I had long searched for a good explanation or picture of what Ariane 5 used for TPS (especially how it compared to the Shuttle's ET, when particle release was a concern for STS - I still wonder how it compares).
Ariane V doesn't have any debris concerns with the insulation as it doesn't have an orbiter hanging off it that has a fragile TPS. So that was something unique to the shuttle.

Obviously :) But there must exist some level of knowledge, if perhaps not as detailed as STS with its cameras and cryopumping studies. Large TPS shedding might be damaging to other LV parts as well (see STS-112)
Ariane has not experienced any significant loss of insulation tiles since they started using them on the H8 upper stage on Ariane 1.

Offline eeergo

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On Ariane V, they use 2 cm thick insulating tiles made from expanded polyurethane.

http://www.sciencephoto.com/media/87848/view

Thank you for that, I had long searched for a good explanation or picture of what Ariane 5 used for TPS (especially how it compared to the Shuttle's ET, when particle release was a concern for STS - I still wonder how it compares).
Ariane V doesn't have any debris concerns with the insulation as it doesn't have an orbiter hanging off it that has a fragile TPS. So that was something unique to the shuttle.

Obviously :) But there must exist some level of knowledge, if perhaps not as detailed as STS with its cameras and cryopumping studies. Large TPS shedding might be damaging to other LV parts as well (see STS-112)
Ariane has not experienced any significant loss of insulation tiles since they started using them on the H8 upper stage on Ariane 1.

This begs the question: was the panel solution studied for STS?
-DaviD-

Online DaveS

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On Ariane V, they use 2 cm thick insulating tiles made from expanded polyurethane.

http://www.sciencephoto.com/media/87848/view

Thank you for that, I had long searched for a good explanation or picture of what Ariane 5 used for TPS (especially how it compared to the Shuttle's ET, when particle release was a concern for STS - I still wonder how it compares).
Ariane V doesn't have any debris concerns with the insulation as it doesn't have an orbiter hanging off it that has a fragile TPS. So that was something unique to the shuttle.

Obviously :) But there must exist some level of knowledge, if perhaps not as detailed as STS with its cameras and cryopumping studies. Large TPS shedding might be damaging to other LV parts as well (see STS-112)
Ariane has not experienced any significant loss of insulation tiles since they started using them on the H8 upper stage on Ariane 1.

This begs the question: was the panel solution studied for STS?
AFAIK, no. They really did not care about foam loss from the ET until after STS-107. And it wouldn't have done much good any way. The critical foam loss areas were the protuberances(bipod spindles, pressurization line brackets etc), not the acreage foam on the actual tanks.
« Last Edit: 12/18/2017 02:41 PM by DaveS »
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Offline Wayne Hale

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I'm no expert on SLS or the insulation trades that have been made there. However, I can help a little with the shuttle history which may be of interest in this discussion.  During early shuttle design, and again after STS-107 there was considerable effort made to look at putting the insulation on the inside of the tank rather than the outside.  The conclusion at both times was that there was considerable risk that foam could come off and be ingested into the engine turbopumps with catastrophic results.  So the foam remained outside.

Foam loss was a significant issue for the shuttle program even before STS-107 and efforts were made to reduce foam shedding during ascent in several areas . . . but as we later learned, not enough effort was made to eliminate the losses.  Prior to STS-107, as we all infamously know now, foam loss during ascent was considered a nuisance problem that resulted in minor orbiter tile damage increasing turnaround time between flights.

Losses of the robotically sprayed 'acreage' foam were minimal, most of the foam losses occurred in the hand crafted specialty areas like the ice/frost ramps, PAL ramp, and of course the bipod ramp.  After much investigation these foam on foam areas were subject to differential thermal expansion which caused loss of significantly sized foam.

Foam insulation was necessary for the shuttle to maintain propellant 'quality' - temperature and density.  Boiloff would have been high, but the loss of density of the LOX and LH2 would have made significant ascent performance losses if the foam had not been there.  And ice formation was always a concern.  Much of the foam was sized to ensure the outer tank surface stayed at or above 32 deg F under most conditions.  The Final Inspection Team ensured that there were no areas of ice formation where there were imperfections in the insulation, etc.

Intertank insulation was required for ascent heating primarily although it did help with the prelaunch time while tanked on the launch pad.  It not only prevented heat transfer into the propellant tanks but preserved the material strength of the aluminum skin of the intertank during the aeroheating of ascent.

That is a quick summary.  I expect the SLS team - which has a lot of shuttle veterans - are making engineering trades for all of this, not simply doing it 'because the shuttle did it'.  In fact, I would go further to state that there is a conscious mind set to do things differently than shuttle with most of the SLS team, as far as I have interacted with them.

Offline mike robel

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Wayne,

Thanks for your perspective.  It is very illuminating for me.  However, I note the Saturn SIVB had internal insulation and proved to be a very reliable booster, as discussed in https://history.nasa.gov/SP-4206/ch6.htm.  There was no mention of engine ingestion in the cited work.

The S-II had external insulation, at first in premolded pieces (which had a lot of problems), and later it was sprayed on.

I wonder if the external insulation was selected because the shuttle tank was not constructed by McDonnel-Douglas, but by Martin (if I recall correctly) and then by North American Rockwell (I think) and still later Boeing?

Mike


Offline Markstark

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This may be relevant to the discussion

Offline mike robel

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Online DaveS

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Wayne,

Thanks for your perspective.  It is very illuminating for me.  However, I note the Saturn SIVB had internal insulation and proved to be a very reliable booster, as discussed in https://history.nasa.gov/SP-4206/ch6.htm.  There was no mention of engine ingestion in the cited work.

The S-II had external insulation, at first in premolded pieces (which had a lot of problems), and later it was sprayed on.

I wonder if the external insulation was selected because the shuttle tank was not constructed by McDonnel-Douglas, but by Martin (if I recall correctly) and then by North American Rockwell (I think) and still later Boeing?

Mike


NAR was the orbiter vehicle only. NAR subsequently became Rockwell Intl and was bought by Boeing. Martin-Marietta was bought up by Lockheed creating Lockheed Martin.
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"We're rolling in the wrong direction but for the right reasons"
-USA engineer about the rollback of Discovery prior to the STS-114 Return To Flight mission

Online envy887

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...
Intertank insulation was required for ascent heating primarily although it did help with the prelaunch time while tanked on the launch pad.  It not only prevented heat transfer into the propellant tanks but preserved the material strength of the aluminum skin of the intertank during the aeroheating of ascent.
...

Is this due to the booster nose cone shockwaves impinging on the intertank? I don't know of any other multicore vehicle that insulates the intertank or interstage with SOFI, though DIVH and FH do both appear to have insulation there.

Offline JohnF

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Very very basic question, common sense wise, why get away from the Saturn V design for a rocket going to the moon ?, the blueprints for man's greatest machine surely still exist. The shuttle design booster seems to troublesome, from foam to O rings etc. I suppose I will answer my own question, tooling perhaps ?

Online DaveS

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Very very basic question, common sense wise, why get away from the Saturn V design for a rocket going to the moon ?, the blueprints for man's greatest machine surely still exist. The shuttle design booster seems to troublesome, from foam to O rings etc. I suppose I will answer my own question, tooling perhaps ?
The o-rings are since long fixed and the foam is of no concern to an inline vehicle really. The tooling and engineering knowledge that went into the Saturns are since long gone. Recreating it would essentially be creating it anew.
"For Sardines, space is no problem!"
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"We're rolling in the wrong direction but for the right reasons"
-USA engineer about the rollback of Discovery prior to the STS-114 Return To Flight mission

Offline Hog

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Very very basic question, common sense wise, why get away from the Saturn V design for a rocket going to the moon ?, the blueprints for man's greatest machine surely still exist. The shuttle design booster seems to troublesome, from foam to O rings etc. I suppose I will answer my own question, tooling perhaps ?
There are no issues related to SOFI or SRB O-rings as related to SLS.  Any shed foam wont hit the vehicle like the sidemounted Orbiter Vehicles, remember all that ice that fell when the F-1s came to life?
O-rings were redesigned for the 1st RTF back almost 30 years ago now.

We were lucky IMO to get away from the Apollo program without a LVLC.  Saturn-V as mans greatest machine, interesting view.

I'm sure there are budgetary concerns as well.  There was also a big push to use Shuttle derived technologies.
Paul

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