Author Topic: Boeing starts final assembly for NASA’s first SLS Core Stage + second  (Read 1749 times)

Online Chris Bergin

FEATURE ARTICLE: Boeing starts final assembly for NASA’s first SLS Core Stage, work picks up for the second -

https://www.nasaspaceflight.com/2019/01/boeing-final-assembly-nasas-first-sls-core-work-second/

By Philip Sloss speaking with John Shannon (Former Space Shuttle Program Manager, now Boeing SLS).

Lead render by Nathan Koga for NSF/L2

https://twitter.com/NASASpaceflight/status/1089953087694032896

Online dlapine

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Nice article, and glad to see progress on the first SLS core, but I'm left a little unclear as to what was actually finished. My take was that the intertank, LOX and forward skirt had been assembled and set aside.

I took it that work was still to be done on the LH2 tank and boattail engine section?

Offline MATTBLAK

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Extremely good article. Concise and info-dense. My complements to the chef(s).
"Those who can't, Blog".   'Space Cadets' of the World - Let us UNITE!! (crickets chirping)

Offline eeergo

Fantastic article, thank you for this exciting, positive (!) update on the biggest piece for EM-1 (and -2).

Nice article, and glad to see progress on the first SLS core, but I'm left a little unclear as to what was actually finished. My take was that the intertank, LOX and forward skirt had been assembled and set aside.

I took it that work was still to be done on the LH2 tank and boattail engine section?

The upper "join" (the composite formed by the forward skirt, that is, the adapter to the second stage, plus the LOX tank plus the intertank) has been finished and mated with no issues. The LOX S-ducts that run down from the bottom of the LOX tank through the intertank to the engines are being assembled now (equivalent to the single large LOX feedline that ran down the length of the ET in the Shuttle), as well as closeout foam work in the joints where the bolts were just torqued, plus instrumentation and other miscellaneous minor tweaks.

The engine section is progressing but still has major work pending, like finishing ~30% of the wire harnesses and checking them out, plus installing the large LH2 internal feedlines that take up a lot of space and can't be put in place until the wiring is done. The boattail (ready now) can be then mated to the engine section in a 2 month-long process, to then allow the lower "join" (LH2 tank + engine section) to be mated together too.

The LH2 tank is all but complete, and since it appears they're early with that, they started "get-ahead" work by installing the twin external LOX feedlines.

So right now it seems the engine section is the bottleneck, but the two halves of CS-1 should be ready for mating sometime in the spring (3-4 months from now?).

My own question: how does this couple with the STA tests?
-DaviD-

Offline psloss

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My own question: how does this couple with the STA tests?
Completing assembly of the first flight stage is still more critical schedule-wise than finishing the intertank and LH2 tank STA testing.  (Testing of the engine section STA was completed early in 2018.)

They don't need to analyze the LOX tank loads data for the Green Run hot-fire, just the relevant test cases for the engine section, intertank, and LH2 tank.

Offline eeergo

My own question: how does this couple with the STA tests?
Completing assembly of the first flight stage is still more critical schedule-wise than finishing the intertank and LH2 tank STA testing.  (Testing of the engine section STA was completed early in 2018.)

They don't need to analyze the LOX tank loads data for the Green Run hot-fire, just the relevant test cases for the engine section, intertank, and LH2 tank.

Thanks!

Followup: could you refresh my mind as to why the upper join/LOX STA is taking at least the same, if not more, time to complete than the CS-1's equivalent? Is it because of the welding problems that cropped up a while ago affecting the STAs but being solved by the time CS-1 was built, or just because of the schedule priorities (which seems counter-intuitive since the STAs are *test* articles, after all)?

Also, if I may ask: when's the Green Run expected to happen? I assume the two STA joins for that will be mated vertically instead of the flight version's horizontal approach, right?
-DaviD-

Offline psloss

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The structural test articles are only being tested as individual elements, not as an integrated element.  Recall that the last test case for the engine section STA was a margin test to figuratively take it to "failure":
https://www.nasaspaceflight.com/2018/03/pegasus-sls-test-article-nasa-marshall-tests/

(NASA is considering the same test to failure for each of the STAs.)

The LOX STA is a lower priority in this situation -- they don't need to complete the loads analysis for Green Run and they don't want to get in the way of construction/production of the first two flight stages.

Also, the STAs are passive, non-functional structures -- the Green Run hot-fire test will be run on the flight stage.  IIRC, the last forecast on the timing for that was end of 2019, beginning of 2020; however, that's stale and everyone at NASA was furloughed for the last five weeks.

Offline Khadgars

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Very nice article, always top notch.  It's refreshing to finally see all the stages coming together.

Offline envy887

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IIRC, the last forecast on the timing for that was end of 2019, beginning of 2020; however, that's stale and everyone at NASA was furloughed for the last five weeks.

From your article in mid-May, the CS-1 green run hotfire was 10.5 months out:
https://www.nasaspaceflight.com/wp-content/uploads/2018/05/nac_march_2018_hill_-_smith_3-23-2018_final.EM-1-IMMS.Slide-2-W-Insert.jpg

More than 8 months later, it's now some 11 months out?

Is the Orion CM/SM still the critical path to EM-1, and has that slipped similarly?
« Last Edit: 01/29/2019 10:05 pm by envy887 »

Offline ncb1397

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IIRC, the last forecast on the timing for that was end of 2019, beginning of 2020; however, that's stale and everyone at NASA was furloughed for the last five weeks.

From your article in mid-May, the CS-1 green run hotfire was 10.5 months out:
https://www.nasaspaceflight.com/wp-content/uploads/2018/05/nac_march_2018_hill_-_smith_3-23-2018_final.EM-1-IMMS.Slide-2-W-Insert.jpg

More than 8 months later, it's now some 11 months out?

Is the Orion CM/SM still the critical path to EM-1, and has that slipped similarly?

Not exactly. There is an update date stamp of 2/28/2018, which got presented in a 3/26/18 NAC, which got published in a 5/14/2018 NasaSpaceFlight.com article. It looks like Mid March 2019 was the data presented there, which would be 12.5 months out.

edit: and the rabbit hole goes even deeper. The top right corner of that sheets indicates the data is from end of December 2017 even if the graphic is from a couple months later. If so, that would indicate that at that time, it was 14.5 months out.
« Last Edit: 01/29/2019 10:19 pm by ncb1397 »

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