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NASA and Teledyne Brown recently completed major welding of the LVSA at the Advanced Weld Facility at Marshall. The structure is primarily made up of sixteen 2195 aluminum alloy panels.<\/p>\nNASA is getting ready to apply spray-on foam insulation (SOFI) to the outside of the Launch Vehicle Stage Adapter (LVSA) that will fly as a part of the Space Launch System (SLS) launch vehicle on Exploration Mission-1 (EM-1). The LVSA is a roughly thirty feet by thirty feet conical spacer structure that connects the top of the SLS Core Stage with the Interim Cryogenic Propulsion System (ICPS) upper stage that will fly on EM-1.<\/p>\n
LVSA:<\/p>\n
Built by NASA and prime contractor Teledyne Brown Engineering, the LVSA will shortly begin preparations at the National Center for Advanced Manufacturing in Building 4707 at the Marshall Space Flight Center (MSFC) in Huntsville, Alabama, for a few months of foam application work.<\/p>\n
Following some additional work at Marshall, the LVSA will be shipped to the Kennedy Space Center (KSC) in Florida next year.<\/p>\n
The flight article is the second unit completed; the first unit, a structural test article, was used in integrated structural tests at Marshall this year with the other elements that connect the Orion spacecraft with the ICPS and the SLS. In Building 4707 at Marshall, a clean area is ready for the foam application work to take place.<\/p>\n
NASA and Teledyne Brown recently completed major welding of the LVSA at the Advanced Weld Facility at Marshall. The structure is primarily made up of sixteen 2195 aluminum alloy panels.<\/p>\n
\u201c2195 panels [and] 2219 rings,\u201d noted Jon Street, manufacturing lead for the LVSA in the Marshall engineering directorate. \u201cThat\u2019s a segmented ring on the bottom [and] a solid forging that\u2019s machined into a ring at the forward end.\u201d (2219 is another aluminum alloy that is used extensively on the SLS Core Stage structures.)<\/p>\n
Due to its dimensions, the adapter had to first be welded into two cones, forward and aft, which were then welded to complete the structure.<\/p>\n
\u201cI don\u2019t have a tool that can get twenty-eight feet tall,\u201d Street added. \u201cWe build the forward cone first with vertical welds and there are eight of them. It takes about five weeks to do it. Basically what we do is we weld up seven of the joints and then we have to measure it to figure out the final arc length for the top and bottom that we need to do to maintain a cone.<\/p>\n
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\u201cThat takes about a week of scanning and analysis. Then we trim that last one and we weld it. So once you make that cone, you\u2019re stuck with that cone, so the top and the bottom diameter has to be [correct].\u201d<\/p>\n
\u201cI build it like a cake \u2014 I take the forward off, reconfigure the tool, and then I build the aft, and it\u2019s a cone, so I\u2019m trying to hit a target diameter, but I\u2019m not trying to get too small or too short, either. So I\u2019ve got to manage all that.\u201d<\/p>\n
\u201cOnce we weld those two together, I want to make sure the flange is centered \u2014 the axis to the top of the cone \u2014 and then once I weld that bottom, I trim that middle joint area, and load the top cone on, and then start trimming until I get the two pieces where I need it. Because you have to have the panels fairly flat \u2014 you cannot have \u2018step\u2019 in it.\u201d<\/p>\n
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\u201cThe cone part of it that people have trouble with is if I trim it to meet a diameter, I could trim it so it\u2019s too short. You can\u2019t weld it unless you get the two diameters right so the biggest challenge was maintaining axial center and parallelism.\u201d<\/p>\n
The panels were welded using conventional friction stir welding, while the circumferential welds of the rings to the top and bottom used self-reacting friction stir welding. The rings at the top and the bottom of the adapter, also called flanges, are structural attach points to other parts of the launch vehicle.<\/p>\n
The bottom flange is essentially identical to the flanges that will be on the Core Stage elements and will be bolted to the top flange of the Forward Skirt during vehicle integration in the Vehicle Assembly Building at the Kennedy Space Center in Florida. The adapter\u2019s top flange will attach with a frangible joint assembly to the ICPS.<\/p>\n
During flight, the Orion-ICPS stack will separate from the Core Stage at the LVSA top flange, with the LVSA remaining attached to the Core Stage.<\/p>\n
TPS foam application:<\/p>\n
Unlike the static testing of the STA done on the ground, the flight unit needs thermal protection from the atmospheric heating it will see during ascent, so it received a coat of primer in preparation for applying spray-on foam insulation on top of that.<\/p>\n
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\u201cThere\u2019s some pretty high heat loads in some places,\u201d Mindy Nettles, the SLS manager for the LVSA said about the requirement for insulation. \u201cWe don\u2019t have any cryo exposure, it\u2019s just the ascent heating.\u201d<\/p>\n
Once work begins, the first task is to prepare the surface, beginning with cleaning.<\/p>\n
\u201cThe first thing that we\u2019ll do is a solvent wipe. We\u2019ll wipe down the whole hardware with a\u2026cleaner that we use for these substrates,\u201d Michael Frazier, branch chief for the Non-Metallic Materials Division in Marshall\u2019s Materials and Processes Lab added.<\/p>\n
Next, the weld lands where the panels were joined together side-by-side and top-to-bottom will be painted with primer.<\/p>\n
\u201cThe panels came pre-primed and then we\u2019ll just fill in the weld lands,\u201d Amy Buck, thermal protection system expert in Marshall\u2019s Materials and Processes Lab, said. \u201cWe will roll that material on with just paint rollers \u2014 that\u2019s why we tried to minimize the area that we had to do.<\/p>\n
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\u201cSo the panels were pre-primed with a spray process and then we\u2019ll do the rolling process on the weld lands. And then once we get all that done we\u2019ll start the foam application.\u201d<\/p>\n
\u201cWe have a very skilled crew of technicians that are ready to do this job.\u201d<\/p>\n
The type of spray-on foam used on the LVSA will be manual spray. Although similar in chemistry, each of the three foam application processes used on SLS hardware has its own formulation.<\/p>\n
Besides the manual spray foam, there is a robotically-sprayed foam (also called \u201cauto spray\u201d) that is used at the Michoud Assembly Facility in New Orleans on the barrels of the large Core Stage propellant tanks, and a pour foam that is used for hardware with more complex shapes, like Core Stage propellant feedlines and valves.<\/p>\n
The manual spray foam was chosen for the LVSA for a few reasons.<\/p>\n
\u201cThis is one of the largest manual sprays that\u2019s ever been done,\u201d Buck explained. \u201cWe don\u2019t have the equipment to do the automatic spray in this facility. The automatic equipment we have here at Marshall is much smaller so we had to go back to a manual process to do the larger article here. So we\u2019ll split it into sections and do a section at a time.\u201d<\/p>\n
\u201cThis manual spray foam that we have here is more robust as far as the temperatures and humidities that you can apply it in,\u201d Frazier added. \u201cWe can apply that at room temperature. The robotically-applied foam that goes on the [Core Stage propellant] tanks [requires] a temperature and humidity controlled booth to do that operation.<\/p>\n
\u201cThey are sprayed at much higher temperatures, environment-wise, and much lower humidities than what we\u2019re able to do here with the manual spray foam. [Manual spray] gives us more range, more capability for applying foam.\u201d<\/p>\n
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Additionally, since the SLS Block 1 vehicle is only planned to be flown once, producing this stage adapter is a \u201cone-off\u201d job, as is the foaming operation for it.<\/p>\n
The sprays will be done by hand; two technicians standing up on a lift will alternate using a hand-held spray gun.<\/p>\n
\u201cWe have a portable dispense unit that will carry the foam materials,\u201d Buck said. \u201cThere will be two component materials that stay separate until [they get] to the gun. And so when they come together in the gun it will go straight onto the substrate and then react and rise. So it actually starts immediately when it gets into the gun.\u201d<\/p>\n
The materials will stay on the ground with hoses for each running up to the gun where they are combined.<\/p>\n
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\u201cIt will be one spray gun, two guys operating one gun,\u201d Buck explained.<\/p>\n
\u201cThey\u2019ll switch off as they go up. The material that\u2019s in the two drums will stay on the ground along with the actual pumping equipment will also be on the ground and the material will then go through hoses up. There will just be two guys and a hose with the gun.\u201d<\/p>\n
The team has been practicing for the work by spraying on a test panel.<\/p>\n
\u201cWe have one of the panels \u2014 one sixteenth of the full article \u2014 over in our other development facility and we\u2019ve been spraying on it so that we can get everything right,\u201d she explained. \u201cWe\u2019re spraying the whole acreage and then down here where this ramp is, where it goes towards the [bottom] flange, we will actually spray part of that, too.<\/p>\n
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\u201cSo our spray foam technicians have been working on how to make that ramp from a manual process in a net spray, so they won\u2019t have to go back and shave [the foam] to get that ramp. They\u2019re going to build it up as they spray the article.\u201d<\/p>\n
For the LVSA, the technicians will spray alternating strips on one panel at a time.<\/p>\n
\u201c[For] this particular operation we\u2019re going to mask off sixteen vertical strips, because that\u2019s about the limit that the guy can do in the cart that he\u2019s going to be up in,\u201d Frazier explained. \u201cSo we mask off everything but those strips that we\u2019re going to be working on. We\u2019ll spray that strip and then we\u2019ll remove the masking.\u201d<\/p>\n
\u201cWe\u2019re actually going to alternate a space over so we don\u2019t get overspray onto the article next to it. And then after we do those sixteen alternating sprays, then we\u2019ll come back and do the ones that are in between.<\/p>\n
\u201cWe use what we call a tie-coat \u2014 you actually have to prep that surface of the foam that you did spray. You cut it and then you tie-coat it, it\u2019s an adhesive material that you put in there. You let that dry and then you spray foam into those other alternating sixteen segments that you have.\u201d<\/p>\n
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As they build up the foam, they will use a tool to measure until they reach the specified thickness.<\/p>\n
\u201cWe have a dualscope gauge, which is an eddy current gauge,\u201d Frazier noted. \u201cWe actually touch the surface of the foam and it can read the distance to the metal that is behind it on the substrate.\u201d<\/p>\n
The work is planned to take a few months.<\/p>\n
\u201cWe will have the article through December working on it, to spray it,\u201d Buck said. \u201cWe have about two months of foam work and about a month of primer.\u201d<\/p>\n
Like house painting, most of the time involved is getting set up to do a spray.<\/p>\n
\u201cThere\u2019s more time spent probably prepping the hardware and getting it ready than is [spent on] the actual operation of putting the foam and the paint on. It\u2019s more masking and removing and curing, letting stuff go through the normal process and then checking the thicknesses. There\u2019s a lot of [work besides] just applying the material to the hardware.\u201d<\/p>\n
Next Steps:<\/p>\n
After the foam application is complete, the LVSA will be moved to another area for additional work.<\/p>\n
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\u201cWhen we\u2019re through, then we\u2019ll move to another building, that\u2019s taller and we will attach the frangible joint assembly,\u201d Nettles said. \u201cTeledyne Brown will then finish up some work on the interior of the cone, some internal platforms that have to be used for work to get to the cryo propulsion stage (the ICPS) and then we will board the Pegasus barge and go to the Cape.\u201d<\/p>\n
Nettles said the barge trip for the adapter from Marshall to Kennedy is currently planned for the summer of next year.<\/p>\n
The LVSA will eventually take its place on the rocket in the VAB at Kennedy, when it is stacked on the Core Stage. It will be lifted up into High Bay 3 and positioned on top of the Forward Skirt, where workers on an elevated platform on Level E will install 360 bolts around the circumference where the flanges on the two pieces meet.<\/p>\n
The same type of manually sprayed foam will then be used to \u201ccloseout\u201d the bolted flanges.<\/p>\n
Some time later, the ICPS will be lifted into the High Bay 3 integration cell and attached to the frangible joint assembly on the top of the LVSA.<\/p>\n
(Images: NASA and Philip Sloss via L2 which includes, presentations, videos, graphics and internal \u2013 interactive with actual SLS engineers \u2013 updates on the SLS and HLV, available on no other site. SLS render by L2 Artist Nathan Koga. The full gallery of Nathan\u2019s (SpaceX Dragon to MCT, SLS, Commercial Crew and more) L2 images can be *found here*))<\/p>\n
To join L2, click here: \/\/www.nasaspaceflight.com\/<\/p>\n","protected":false},"excerpt":{"rendered":"
NASA is getting ready to apply spray-on foam insulation (SOFI) to the outside of the Launch Vehicle Stage Adapter (LVSA) that will fly as a part of the Space Launch System (SLS) launch vehicle on Exploration Mission-1 (EM-1). The LVSA is a roughly thirty feet by thirty feet conical spacer structure that connects the top of […]<\/p>\n","protected":false},"author":1,"featured_media":30017,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"inline_featured_image":false,"footnotes":"","_links_to":"","_links_to_target":""},"categories":[2],"tags":[3718,7866,624],"class_list":["post-38708","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-news","tag-em-1","tag-maf","tag-sls"],"acf":[],"_links":{"self":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/38708"}],"collection":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/comments?post=38708"}],"version-history":[{"count":0,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/38708\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/media\/30017"}],"wp:attachment":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/media?parent=38708"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/categories?post=38708"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/tags?post=38708"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}