The SRB-derived launch vehicle for the Crew Exploration Vehicle (CEV) recently changed from a four-segment SRB, with one Space Shuttle Main Engine (SSME) on the upper stage, to a booster comprised of a five-segment SRB with single J-2X upper-stage engine. <\/p>\n
ESAS Lead Dr. Doug Stanley of Georgia Tech explained that this revised design for the Crew Launch Vehicle (CLV) was actually a preferred design of many on the ESAS team, but had originally been dropped for schedule reasons.\n <\/p>\n
<\/font><\/p>\n When NASA unveiled its Exploration Systems Architecture Study (ESAS) report in September, the original plan was to launch the CEV atop the 4-segment\/SSME CLV. However, the aforementioned scheduling changes surrounding an expendable air-start version of the SSME prompted engineers and designers to switch to the 5-segment design \u2013 with a single J-2X engines. The new design will have a slightly smaller payload capacity than the 4-segment booster.<\/font> <\/font><\/p>\n <\/p>\n The decision to go to the 5-segment booster reverts to a CLV design that was a favourite of many ESAS team members, narrowly edged out in the end by the 4-segment CLV for schedule reasons, according to Dr. Stanley.<\/p>\n \u2018We switched to the 4 segment with SSME at the last minute to enable flying in 2011, which is no longer an option in the budget,\u2019 Dr. Stanley explained in a Q and A session with NASASpaceflight readers on the site\u2019s forum. \u2018Once the schedule slipped to 2012, the 5 segment CLV with J-2S becomes the preferred approach based on our report. The 4-segment with SSME was only preferred if you had to fly in 2011.\u2019<\/p>\n Dr. Stanley also noted how narrowly the 4-segment CLV had originally triumphed over the 5-segment design. \u2018The ESAS effort did not just select a single \u2018right\u2019 answer\u2026it was a very open architecture. We examined a wealth of alternatives, and in many areas the decision as to which was preferred was a very close one\u00e2\u20ac\u00a6NASA has a continuing architecture analysis capability in place to assess the impacts of changes.\u2019<\/p>\n In fact, due to commonality with the Shuttle-derived heavy-lift (SDLV) launcher, the 5-segment CLV should actually save on development costs in the long term, he noted. <\/p>\n \u2018The 5-segment solid with a J-2S was actually the lowest life-cycle cost approach, because you will eventually need to develop the J-2S and 5-segment solid anyhow [for the HLLV],\u2019 Dr. Stanley added. He explained that, since an air-start SSME has never been developed, while the J-2S has already been built and tested, \u2018this [way] you don\u2019t ever have to worry about the cost and risk of the altitude start SSME.<\/p>\n <\/font><\/font><\/p>\n \u00e2\u20ac\u0153No new risks on the [altitude-start] SSME [were] discovered\u2026but avoiding it would be great\u2026The problem is finding the extra $1B+ through 2012 to switch launch vehicles to one with a lower Life Cycle Cost.\u2019<\/p>\n <\/font><\/font> CLV\/CEV section: The SRB-derived launch vehicle for the Crew Exploration Vehicle (CEV) recently changed from a four-segment SRB, with one Space Shuttle Main Engine (SSME) on the upper stage, to a booster comprised of a five-segment SRB with single J-2X upper-stage engine. ESAS Lead Dr. Doug Stanley of Georgia Tech explained that this revised design for the […]<\/p>\n","protected":false},"author":1,"featured_media":0,"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":[],"class_list":["post-42165","post","type-post","status-publish","format-standard","hentry","category-news"],"acf":[],"_links":{"self":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/42165"}],"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=42165"}],"version-history":[{"count":0,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/42165\/revisions"}],"wp:attachment":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/media?parent=42165"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/categories?post=42165"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/tags?post=42165"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
Dr. Stanley thread:
<\/u>http:\/\/forum.nasaspaceflight.com\/forums\/thread-view.asp?tid=1258&start=1<\/p>\n
<\/u>http:\/\/forum.nasaspaceflight.com\/forums\/forum-view.asp?fid=5<\/p><\/p>\n","protected":false},"excerpt":{"rendered":"