![\"\"](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2018\/07\/AR-22_July1_2018.35pct.jpg\")
<\/p>\nAerojet Rocketdyne successfully completed a nearly two-week long rapid-turnaround test-firing demonstration of a Space Shuttle Main Engine (SSME) on July 6 at the Stennis Space Center in Mississippi.\n<\/p>\n
Primarily built from hardware long in storage, the parts rebuild of the reusable engine is called the AR-22 and it is being qualified for use in the Experimental Space Plane (XSP) vehicle that is being designed and built by Boeing for the U.S. military Defense Advanced Research Projects Agency (DARPA).<\/p>\n
The XSP is intended to evaluate a launch vehicle that can be operated on a daily basis to deliver small class payloads. Boeing is developing a reusable plane as a first stage booster that will launch vertically like a rocket, using a single AR-22 engine from Aerojet Rocketdyne.<\/p>\n
The plane can carry an expendable upper stage payload out of the atmosphere and up to speeds of Mach 10, release the payload, and then glide back to Earth and land conventionally.<\/p>\n
Ten tests in ten days<\/p>\n
Also known as the Phantom Express, a key capability targeted for the XSP is rapid reuse. The vehicle will be powered by a single AR-22 engine and the goal of the test series was to demonstrate that it could be hot-fired every 24 hours for ten consecutive days.<\/p>\n
\u201cThis test campaign that we just finished, which is the firing of 10 [times] in 10 days, was a significant \u2018go\/no-go\u2019 milestone for us in order for us to move forward with the program,\u201d Scott Wierzbanowski, DARPA\u2019s Program Manager for XSP, said during a teleconference on July 10. \u201cWe needed to show that the main propulsion system, the AR-22, could in fact support rapid turn operations.\u201d<\/p>\n
<\/p>\n
AR-22 engine in mainstage operation during firing on July 1. Credit: Aerojet Rocketdyne.<\/p>\n
\u201cWhat you\u2019ll see is that we were extremely successful. We completely destroyed previously held records of how you deal with a liquid hydrogen, liquid oxygen type engine and shattered this idea that these types of engines can\u2019t be used in a very operable and very aircraft-like way.\u201d<\/p>\n
SpaceX launch tickets (adsbygoogle = window.adsbygoogle || []).push({});<\/p>\n The demonstration test series began with a 100-second test firing in the A-1 test stand at Stennis on June 26 and was successfully completed on July 6. \u201cWe scored a perfect \u2018ten\u2019 last week,\u201d Jeff Haynes, Aerojet Rocketdyne\u2019s Program Manager for AR-22, said.<\/p>\n \u201cWe broke down the ten days into 240 hours, that\u2019s from the start of the first test to the end of the last test and we had sixty-eight minutes to spare when we finished the last test.\u201d<\/p>\n The test team worked around the clock to accomplish the objective, dodging both typical Summer thunderstorms and more organized, tropical system-like weather.<\/p>\n \u201cWe did have Mother Nature intervene on a couple of occasions where we had two very direct lightning strikes to the test facility,\u201d Haynes noted. \u201cThose resulted in some level of damage to the facility that we had to scramble and repair to stay on track to complete the test series.\u201d<\/p>\n \u201cWhich we did,\u201d he added, \u201cand that\u2019s really a testament of the blended test approach team that we had with NASA, the S3 (Syncom Space Services) contractor, DARPA, and Aerojet Rocketdyne all pulling together with two twelve-hour shifts round the clock 24\/7 to get this done.\u201d<\/p>\n AR-22 engine begins July 2nd test in A-1 test stand at Stennis. Credit: Philip Sloss for NSF\/L2.<\/p>\n Haynes also noted that the average turnaround time between tests was about eighteen and half hours, with the shortest time being seventeen hours from one test to the next.<\/p>\n The primary challenge to restarting the engine so quickly following last use was drying out all the hardware. \u201cWhen we test fire the engine it generates a large amount of moisture within the internal cavities of the engine and trying to run the engine again without drying that out would lead to catastrophic events,\u201d Haynes explained.<\/p>\n \u201cSo when we initially looked at drying the engine, it took about seventeen hours so the team got together and did some pretty innovative concepts and ideas to get it down. One of the test series we got as low as six hours to get it completed through drying and out to inspections.\u201d<\/p>\n \u201cThis vehicle due to the turnaround time, we did limited inspections,\u201d Haynes added. \u201cWe did do some borescope [inspections], we did some torque checks on some of the turbomachinery, and we did nozzle leak checks and things like that, but we did not do the typical Shuttle profile of pulling the pumps from the engine and doing a detailed inspection in that regard.\u201d<\/p>\n \u201cWe have significant instrumentation that allows us to know when we are getting into issues and we have redlines that allow us to abort in that scenario, so we felt running this up to those points would be sufficient and it was successful, so that is the approach we\u2019re taking going forward.\u201d<\/p>\n During the Space Shuttle era, the engines would typically run for around eight minutes in flight and for similar durations in ground testing; for this rapid turnaround test series, the AR-22 was fired for 100 seconds per test.<\/p>\n \u201cWe only need less than 20 seconds to show that the engine can run, go through steady-state and get thermally-stable,\u201d Haynes explained. \u201cWe\u2019re pushing it out this time to get 100 seconds to show that capability exists to go through the 10 times we need to do it to get that durability on the engine proven, as well.\u201d<\/p>\n Exhaust cloud dissipating following AR-22 test on July 2. Credit: Philip Sloss for NSF\/L2.<\/p>\n For the test-series, the engine went through a simpler throttle profile than Shuttle for the shorter tests. \u201cWe would start to 100 percent thrust and then throttle down typically to about 90 percent,\u201d Haynes said.<\/p>\n \u201cThis vehicle, the Phantom Express, only required that level of performance out of this singular engine to achieve the mission profile. We were able on the last test to throttle to 80 percent, which at sea-level there are some challenges with going below that because of the way atmospheric pressure occurs on the engine.\u201d Throttling down below 80 percent thrust at sea-level would cause damaging flow separation in the nozzle.<\/p>\n For XSP flights, the engine run-times will vary based on the performance needed for the payload. \u201cEvery mission, trajectory, and profile is going to be a little bit different, but generally less than half the amount of time it would run for a Shuttle ascent,\u201d Steve Johnston, Boeing Phantom Works Launch Director, said. \u201cSo on the order of three minutes or so, in that ballpark.\u201d<\/p>\n The last hot-fire test ran for an additional forty-seven seconds to demonstrate a new capability developed by Aerojet Rocketdyne that could allow engines to recover from some failure conditions rather than triggering an immediate abort and shutdown.<\/p>\n \u201cWe introduced a health management system that is new to this engine, it\u2019s called Advanced Anomaly and Command and Control Center, AC3,\u201d Haynes explained. \u201cWe actually tricked the engine into thinking it was experiencing a red-line condition, which under the Shuttle program would have been an immediate shutdown of the engine.\u201d<\/p>\n \u201cWe allowed our new software to throttle down the engine automatically, assess the situation, and then do a step-wise recovery of the thrust profile in a matter of seconds to get back to the full throttle. So the engine accomplished this and we were able to keep the engine running, which for this vehicle would be an important reliability feature to have.\u201d<\/p>\n Phantom Express overview<\/p>\n Boeing\u2019s Phantom Works Division is the prime contractor for the Phantom Express. The glideback booster will weigh approximately 240,000 pounds when fueled. It is designed to be able to carry an expendable upper stage up to speeds between Mach 5 and Mach 10.<\/p>\n DARPA\u2019s requirement is for the system to be able to deliver at least 3000 pounds to orbit. \u201cWe are targeting a little bit more capability than that \u2014 our current estimate is about 5000 pounds,\u201d Johnston noted. \u201cOur payload performance varies depending upon what orbital inclination you\u2019re flying, so it varies from three to five-thousand pounds depending upon what altitude and inclination you\u2019re targeting.\u201d<\/p>\n After deploying the upper stage, the booster is an unpowered glider. For lower speed deployments, it will flyback to a landing field at the launch site; for higher speed deployments that take it beyond range of a return to the launch site, it can land on runways downrange.<\/p>\n Artist concept of resuable XSP booster during ascent. Credit: Boeing.<\/p>\n The booster will fly autonomously, using Global Positioning System (GPS) for guidance and navigation. \u201cIt\u2019s not using any of the local aircraft type recovery systems \u2014 no ILS (Instrument Landing System), no PAR (Precision Approach Radar), no localizer,\u201d Wierzbanowski noted.<\/p>\n The rapid turnaround engine demonstration was a major test in Phase 2 of the program, which continues with design and construction of the booster vehicle and integration of the expendable upper stage. Phase 3 will see flight testing of the system, beginning with test flights of the booster itself, then carrying payloads.<\/p>\n Phase 3 is planned to include a similar rapid turnaround demonstration of the vehicle, flying it and turning it around ten times in ten days.<\/p>\n Fabrication of vehicle subassemblies is already underway, with tank construction going on in the Seattle, Washington, area. \u201cThis is a collaborative effort within Boeing between our defense and commercial airplanes and our enterprise technology business,\u201d Johnston said.<\/p>\n \u201cThe same facility up in the Puget Sound area that developed the original technology for the 787 composite fuselage sections is currently fabricating for us our liquid oxygen tank. That liquid oxygen tank is complete through layup and cure, it\u2019s going through inspection now.\u201d<\/p>\n \u201cThe next step after that will be the development of our liquid hydrogen tank and with those two things combined we\u2019ll have about two-thirds of the length of the vehicle fabricated,\u201d he added. In addition, construction of the wings is going on in at Boeing facilities in St. Louis, and software is being developed at facilities in Southern California.<\/p>\n<\/p>\nSee Also<\/h4>\n
\n
![\"\"](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2018\/07\/P1090711.35pct.jpg\")
<\/p>\n![\"\"](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2018\/07\/P1090783.35pct.jpg\")
<\/p>\n![\"\"](\"https:\/\/www.nasaspaceflight.com\/wp-content\/uploads\/2018\/07\/phantom_express_gallery1_960.jpg\")
<\/p>\n