This helps to maintain the propellant temperature in the required range and also keeps the outside of the tank from getting too cold, which would condense and freeze the water vapor in the air into ice; ice is a debris hazard and would add additional weight to the vehicle, reducing overall performance. During the early stages of ascent, the foam also provides thermal protection from aerodynamic heating.
I'm curious: Why does the SLS need foam insulation, while other launchers (such as SpaceX Falcon 9) manage without any such foam insulation?The article says:QuoteThis helps to maintain the propellant temperature in the required range and also keeps the outside of the tank from getting too cold, which would condense and freeze the water vapor in the air into ice; ice is a debris hazard and would add additional weight to the vehicle, reducing overall performance. During the early stages of ascent, the foam also provides thermal protection from aerodynamic heating.I would have thought the foam would impose a greater weight penalty than any condensed ice.
Quote from: cmcqueen on 12/11/2017 12:20 AMI'm curious: Why does the SLS need foam insulation, while other launchers (such as SpaceX Falcon 9) manage without any such foam insulation?The article says:QuoteThis helps to maintain the propellant temperature in the required range and also keeps the outside of the tank from getting too cold, which would condense and freeze the water vapor in the air into ice; ice is a debris hazard and would add additional weight to the vehicle, reducing overall performance. During the early stages of ascent, the foam also provides thermal protection from aerodynamic heating.I would have thought the foam would impose a greater weight penalty than any condensed ice.The SLS uses liquid hydrogen (LH2) fuel and the liquid oxygen (LOX) oxidizer which would boil off without insulation.
Quote from: Rocket Science on 12/11/2017 12:25 AMQuote from: cmcqueen on 12/11/2017 12:20 AMI'm curious: Why does the SLS need foam insulation, while other launchers (such as SpaceX Falcon 9) manage without any such foam insulation?The article says:QuoteThis helps to maintain the propellant temperature in the required range and also keeps the outside of the tank from getting too cold, which would condense and freeze the water vapor in the air into ice; ice is a debris hazard and would add additional weight to the vehicle, reducing overall performance. During the early stages of ascent, the foam also provides thermal protection from aerodynamic heating.I would have thought the foam would impose a greater weight penalty than any condensed ice.The SLS uses liquid hydrogen (LH2) fuel and the liquid oxygen (LOX) oxidizer which would boil off without insulation.Your point about liquid hydrogen is true, but not liquid oxygen. Many (most) other launch vehicles use LOX without jumping through all these hoops for insulating foam.
I'm curious: Why does the SLS need foam insulation, while other launchers (such as SpaceX Falcon 9) manage without any such foam insulation?
Applying foam to the interstage and the forward skirt seems a bit much. Any particular reason why it's being done with SLS?
Applying foam to the intertank and the forward skirt seems a bit much. Any particular reason why it's being done with SLS?
Quote from: Oli on 12/11/2017 09:33 PMApplying foam to the intertank and the forward skirt seems a bit much. Any particular reason why it's being done with SLS?For the same reason most of SLS decisions are justified... Because that's how it was done with Shuttle.No matter what anyone will tell you, this kind of foam is not necessary for LH2, and has many problems. You only need to look back at Saturn V - which flew with two LH2 stages with far longer loiter times - to see that is not necessary.
Although several S-II stages were produced with the original insulation concept, the results were so discouraging that North American spent considerable time and money working up an alternative. Instead of making up panels and affixing them to the tank, the company finally evolved a process for spraying insulation material directly onto the tank walls (eliminating the air pockets), letting it cure, then cutting it to the proper contour. This technique turned out to be much more economical and much lighter than the insulation panels.
Quote from: Lars-J on 12/12/2017 03:23 AMQuote from: Oli on 12/11/2017 09:33 PMApplying foam to the intertank and the forward skirt seems a bit much. Any particular reason why it's being done with SLS?For the same reason most of SLS decisions are justified... Because that's how it was done with Shuttle.No matter what anyone will tell you, this kind of foam is not necessary for LH2, and has many problems. You only need to look back at Saturn V - which flew with two LH2 stages with far longer loiter times - to see that is not necessary. In case you had failed to notice: both LH2 tanks on Saturn V (the one on S-II and the one on S-IVB) were insulated. Boil-off was the prime reason.S-IVB LH2 tank was insulated on the inside. S-II LH2 tank was insulated on the outside.Read from here: https://history.nasa.gov/afj/s-ii/s-ii-insulation.htmlYou will also discover where spray-on-foam originated from: S-II
Quote from: woods170 on 12/12/2017 09:34 AMQuote from: Lars-J on 12/12/2017 03:23 AMQuote from: Oli on 12/11/2017 09:33 PMApplying foam to the intertank and the forward skirt seems a bit much. Any particular reason why it's being done with SLS?For the same reason most of SLS decisions are justified... Because that's how it was done with Shuttle.No matter what anyone will tell you, this kind of foam is not necessary for LH2, and has many problems. You only need to look back at Saturn V - which flew with two LH2 stages with far longer loiter times - to see that is not necessary. In case you had failed to notice: both LH2 tanks on Saturn V (the one on S-II and the one on S-IVB) were insulated. Boil-off was the prime reason.S-IVB LH2 tank was insulated on the inside. S-II LH2 tank was insulated on the outside.Read from here: https://history.nasa.gov/afj/s-ii/s-ii-insulation.htmlYou will also discover where spray-on-foam originated from: S-IIOf course insulation is needed, did I say otherwise? Read again... "this kind of foam". As in what it is and its application method.
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?
On Ariane V, they use 2 cm thick insulating tiles made from expanded polyurethane.http://www.sciencephoto.com/media/87848/view
Quote from: Steven Pietrobon on 12/14/2017 04:27 AMOn Ariane V, they use 2 cm thick insulating tiles made from expanded polyurethane.http://www.sciencephoto.com/media/87848/viewThank 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).
Quote from: eeergo on 12/14/2017 11:18 AMQuote from: Steven Pietrobon on 12/14/2017 04:27 AMOn Ariane V, they use 2 cm thick insulating tiles made from expanded polyurethane.http://www.sciencephoto.com/media/87848/viewThank 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.
Quote from: DaveS on 12/14/2017 11:30 AMQuote from: eeergo on 12/14/2017 11:18 AMQuote from: Steven Pietrobon on 12/14/2017 04:27 AMOn Ariane V, they use 2 cm thick insulating tiles made from expanded polyurethane.http://www.sciencephoto.com/media/87848/viewThank 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)
Quote from: eeergo on 12/14/2017 12:33 PMQuote from: DaveS on 12/14/2017 11:30 AMQuote from: eeergo on 12/14/2017 11:18 AMQuote from: Steven Pietrobon on 12/14/2017 04:27 AMOn Ariane V, they use 2 cm thick insulating tiles made from expanded polyurethane.http://www.sciencephoto.com/media/87848/viewThank 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.
Quote from: woods170 on 12/14/2017 08:11 PMQuote from: eeergo on 12/14/2017 12:33 PMQuote from: DaveS on 12/14/2017 11:30 AMQuote from: eeergo on 12/14/2017 11:18 AMQuote from: Steven Pietrobon on 12/14/2017 04:27 AMOn Ariane V, they use 2 cm thick insulating tiles made from expanded polyurethane.http://www.sciencephoto.com/media/87848/viewThank 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?
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
...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....
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 ?
Quote from: JohnF on 12/26/2017 02:09 PMVery 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 ?Saturn V had a lot of issues and to iron them all out would require an update, essentially, of every piece. And we have a case study on that with J2-X.
Also, weren't the blueprints for it lost in the 70s?