SLS goes orange

[Rune]

Well, this was my source: http://www.nasaspaceflight.com/2015/10/nasa-sls-milestones-converge-debut-flight/

I will quote from your source:

The post-CDR design does include more foam on the top end of the rocket after an additional decision included a call for the LVSA (Launch Vehicle to Stage Adaptor) to have foam on the outside, based on the latest thermal analysis.

Given the LVSA has the core stage LOX tank below it, the ICPS LOX tank inside, and the ICPS LH2 tank above it, it is expected this area of the rocket will become cold during the final countdown and form ice on the outside.

Nothing in there says it will stop the ice forming. It just says they needed additional insulation on top of the LOX tank due to thermal considerations, not only around the LH2 tank. Considering there is a cryogenic upper stage inside that adapter, it makes sense. LOX tanks also need to be bled to avoid overpressure during launch countdown, BTW.

So what is your point, again? I might have misunderstood what you were saying. In any case, yeah, thermally isolating the tanks is done to stop them blowing up, not to stop them forming ice. Pretty much all liquid fuel rockets shed ice on launch, except hypergolics.

Rune. This makes me wonder how they stop ice forming inside the adaptor, around the ICPS, and becoming a problem... or the Centaur on Atlas 5XX series... inert gas to take all water vapour out?

[okan170]

Nothing in there says it will stop the ice forming. It just says they needed additional insulation on top of the LOX tank due to thermal considerations, not only around the LH2 tank. Considering there is a cryogenic upper stage inside that adapter, it makes sense. LOX tanks also need to be bled to avoid overpressure during launch countdown, BTW.

So what is your point, again? I might have misunderstood what you were saying. In any case, yeah, thermally isolating the tanks is done to stop them blowing up, not to stop them forming ice. Pretty much all liquid fuel rockets shed ice on launch, except hypergolics.

Rune. This makes me wonder how they stop ice forming inside the adaptor, around the ICPS, and becoming a problem... or the Centaur on Atlas 5XX series... inert gas to take all water vapour out?

Clarification, the idea is that the foam will drastically reduce the amount of uncontrollable ice buildup on the interstage of both the ICPS and EUS stages. This part of the stage is not related to the tank pressurization and is ventilated to prevent general overpressure like all interstages. The area in question is near the top of the LOX tank dome on the core stage but is not part of the tank itself or its thermal protection. If thermal analysis showed ice remained at manageable levels without the foam, it would have just been painted white. Source on this is an SLS program manager.

[Bill Phil]

That is usually the reason to use white (reflective) albative paint, to shield thermal loads. But where would those come from in this case? The RS-68's? I would buy that, only the core is subjected to the much higher heat load of both boosters, and it doesn't need a highly reflective exterior, even when the heat load would increase pressure on the tank due to boiloff of the fuel. In STS, they were obviously painted to protect form repeated saltwater immersion. Still, the hit in performance from a fancy paintjob must be quite minuscule in the case of the boosters, so you can afford to make it look finished, and not out of the 50's. Which personally would be cool to no end, shiny metallic rockets engineered for performance and nothing else.

As to the CaLV Ares V SLS paintjob in the slides, it is, and will continue to be, the one required to sell the rocket to Congress and (in a distant second place) the public. When it couldn't resemble Constellation, it went back to the glory days of Apollo. I guess the emphasis now is to link it to shuttle hardware, with a few stripes to "make it go faster".

Rune. Speaking without any first-hand knowledge here, let's clarify that.

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Nonsense. That insulation is there to keep the tank from blowing up form the increase in pressure caused by a few thousand tons of hydrogen boiling off as they soak ambient heat on the pad, without venting half your fuel. Pieces of the insulation will still break apart on launch and pose the same impact risk as the usual ice (that will also be present, I'd bet).

RS-68s? Are we talking DIV? SLS uses RS-25s.

[Guest]

This rocket is very quickly living up to its reputation as a space-carrot

Why does that sound so kerbalized?