![\"The](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2013\/04\/A24.jpg\" "\\"The")
That heritage \u2013 which is continuing with SMAT \u2013 ranges back as far as the early days of the Space Shuttle Program (SSP).<\/p>\nThe mini-me version of the Space Launch System (SLS) is now being put through its paces as part of the Scale Model Acoustic Test (SMAT) program. The heavily instrumented five percent scale model of the SLS is being used to provide data on the acoustical energy that could be expected during launch, in turn feeding into the design of Pad 39B\u2019s Sound Suppression System that will be tasked with mitigating the impact on the vehicle.<\/p>\n
SMAT:<\/p>\n
A better definition of the lift-off acoustic environment can be determined from hot fire testing of dynamically scaled models of the launch vehicle and stand.<\/p>\n
That heritage \u2013 which is continuing with SMAT \u2013 ranges back as far as the early days of the Space Shuttle Program (SSP).<\/p>\n
During the Space Shuttle development program, a 6.4 percent scale model of the launch vehicle, propulsion system, launch stand, and exhaust duct system with water suppression was used to refine the analytical\/scaling estimates of the lift-off acoustic environment.<\/p>\n
The resulting data provides a very useful template for the full scale rocket, although final verification of the environment is only fully provided by full static firings or launches of the actual vehicle.<\/p>\n
![\"Z8\"](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2014\/06\/Z81.jpg\")
Notably, the debut launch of the Space Shuttle Program (SSP) \u2013 with Columbia on STS-1 \u2013 showed the importance of understanding the acoustic environments, as the orbiter\u2019s heat shield was damaged when an overpressure wave from the SRBs caused a forward RCS oxidizer strut to fail. Her body flap was also pushed five degrees out of position.<\/p>\n
The subject was also raised during STS-129\u2019s Flight Readiness Review (FRR), as a potential issue with a very small area of the orbiter \u2013 known as a stinger attach point between the RCS and OMS Pod \u2013 raised concerns that recent acoustic environment analysis of the Space Shuttle Main Engines (SSMEs) during ignition could cause stressing that potentially leads to cracks in the attach pins\/stinger.<\/p>\n
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![\"STS-129](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2013\/04\/A221.jpg\" "\\"STS-129")
Although those concerns were based on old and overly conservative data, managers showed their usual due diligence in gathering an array of updated information, via new computational models, borescope inspections on the fleet, and the installation of sensors in the area in question \u2013 all of which would be used to completely allay the potential fear of life fatigue on the stinger.<\/p>\n
Notably, the FRR presentations noted they lacked key historical data, while Main Engine Ignition (MEI) Acoustic & SSME Ignition Overpressure (IOP) Environment data was classed as \u201ccontinually evolving\u201d during the 30 years of the program \u2013 leading to the concern ahead of STS-129.<\/p>\n
Click here for FRR Articles: http:\/\/www.nasaspaceflight.com\/tag\/frr\/<\/p>\n
![\"ASMAT](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2013\/04\/Z46.jpg\" "\\"ASMAT")
The vehicle that was set to replace the Space Shuttle, Ares I, also underwent IOP testing \u2013 with the Ares I Scale Model Acoustics Test (ASMAT) tested during 2010.<\/p>\n
Numerous tests, each using a different pad configuration \u2013 such as with and without water bags within the launch mount \u2013 were conducted at MSFC.<\/p>\n
Quick look test results indicated that the overall noise levels measured on the vehicle were within predicted ranges and the data compared favorably between the firings. However, Ares I was cancelled shortly after the ASMAT firings.<\/p>\n
With SLS now under the acoustical microscope, the SMAT program is using updated approaches for harvesting data from the test firings.<\/p>\n
\u201cThis test is unique because it\u2019s like going through the steps of a true launch, only on a much smaller scale,\u201d said Jeremy Kenny, acoustics engineer at MSFC.<\/p>\n
\u201cThe noise the engines and boosters generate is so great that it can impact the rocket, and the crew, during liftoff. We have to ensure we have the proper suppression system to basically turn that noise down to a safe level.\u201d<\/p>\n
The primary source of the acoustic field is the fluctuating turbulence in the mixing region of the rocket exhaust flow \u2013 known as Engine Generated Acoustics.<\/p>\n
![\"SLS](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2013\/04\/Z76.jpg\")
Engine generated noise is a function of the exhaust flow parameters, launch stand configuration, and to a lesser extent atmospheric conditions.<\/p>\n
Preliminary estimates of the engine generated acoustics at a specified location on the vehicle can be determined by scaling measured acoustic data from previous launch vehicle programs, taking into account the above mentioned flow, configuration, and atmospheric parameters.<\/p>\n
\u201cWhen you\u2019re building the largest rocket in the world, you have to take everything into consideration,\u201d said SLS Chief Engineer Garry Lyles.<\/p>\n
\u201cAcoustic testing is a very critical part of that. We\u2019re using testing techniques that were highly successful during the space shuttle era, and tailoring them to SLS design specifications. It\u2019s getting us where we need to be for the rocket\u2019s first flight.\u201d<\/p>\n
![\"Z6\"](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2014\/06\/Z6.jpg\")
The test stand at MSFC allows for the mini-SLS to be placed at fixed elevations for individual test firings, these being 0, 2.5, 5.0, 7.5, and 10.0 feet. Based on the scale of the ASMAT, these distances corresponded to full-scale elevations of 0, 50, 100, 150, and 200 feet.<\/p>\n
The test vehicle is heavily instrumented, with five primary instrumentation suites resulting in over 325 sensors on the SMAT rocket.<\/p>\n
The instrumentation includes B&K 4944-B microphones and pressure transducers on the tower\/mobile launcher. It also includes far field measurement devices, accelerometers, thermocouples and strain gauges on vehicle, thermocouples, flow meters and chamber pressure instrumentation.<\/p>\n
![\"Z6\"](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2014\/01\/Z68.jpg\")
The tests will ramp up over time, with the opening SMAT firing at the start of this year \u2013 which lasted five seconds \u2013 involving an article that was without its twin imitation boosters.<\/p>\n
Instead, SMAT began testing with small thrusters of its aft, mimicking the RS-25D (Space Shuttle Main Engines) that will be placed on the core of the real life SLS.<\/p>\n
These thrusters \u2013 similar to vintage hardware originally designed in the 1960\u2019s and tested during the Space Shuttle program \u2013 successfully met all test objectives during Phase I scale model acoustic testing at Marshall\u2019s Test Stand 115.<\/p>\n
Testing has now moved on to using the two \u201cbooster\u201d rockets on each side of test article, which utilizes two Rocket-Assisted Take Off (RATO) motors, simulating SLS boosters, with the test requirement calling for the motors ignite simultaneously, as the SRBs would during launch.<\/p>\n
![\"SMAT](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2013\/04\/Z54.jpg\")
Once the test program is complete, the data will feed into the final design of the Sound Suppression System for SLS at Pad 39B.<\/p>\n
The initial model of the system was one of the first items to be built at MSFC for the SMAT tests.<\/p>\n
Work begin in 2012 at Marshall\u2019s test stand 116, with the construction of a working water-based sound suppression system that is now being employed by the SMAT testings.<\/p>\n
The build was finalized after discussions with NASA\/KSC Ground Systems Development and Operations (GSDO) engineers, who are responsible for the full scale system that will be used during SLS\u2019 debut launch at the end of 2017<\/p>\n
(Images via NASA and L2)<\/p>\n
(NSF and L2 are continuing to provide the most extensive and exclusive SLS coverage. To join L2, support the site and access a huge database of content, click here: http:\/\/www.nasaspaceflight.com\/l2\/)<\/p>\n","protected":false},"excerpt":{"rendered":"
The mini-me version of the Space Launch System (SLS) is now being put through its paces as part of the Scale Model Acoustic Test (SMAT) program. The heavily instrumented five percent scale model of the SLS is being used to provide data on the acoustical energy that could be expected during launch, in turn feeding […]<\/p>\n","protected":false},"author":1,"featured_media":30309,"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":[9064,8906,624,9065],"class_list":["post-39562","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-news","tag-mei","tag-msfc","tag-sls","tag-smat"],"acf":[],"_links":{"self":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/39562"}],"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=39562"}],"version-history":[{"count":0,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/39562\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/media\/30309"}],"wp:attachment":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/media?parent=39562"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/categories?post=39562"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/tags?post=39562"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}