Friday, August 5, 2016
SLS Update: A Solid Rocket Booster's Exhaust Plume As Never Seen Before...
Revolutionary Camera Recording Propulsion Data Completes Groundbreaking Test (News Release)
While thousands turned out to watch NASA’s Space Launch System (SLS) recently complete a full-scale test of its booster, few were aware of the other major test occurring simultaneously. NASA’s High Dynamic Range Stereo X (HiDyRS-X) project, a revolutionary high-speed, high dynamic range camera, filmed the test, recording propulsion video data in never before seen detail.
The HiDyRS-X project originated from a problem that exists when trying to film rocket motor tests. Rocket motor plumes, in addition to being extremely loud, are also extremely bright, making them difficult to record without drastically cutting down the exposure settings on the camera. Doing so, however, darkens the rest of the image, obscuring other important components on the motor.
Traditionally, video cameras record using one exposure at a time, but HiDyRS-X records multiple, slow motion video exposures at once, combining them into a high dynamic range video that perfectly exposes all areas of the video image.
The HiDyRS-X project began as part of NASA Space Technology Mission Directorate’s Early Career Initiative (ECI), designed to give young engineers the opportunity to lead projects and develop hardware alongside leading innovators in industry. Howard Conyers, a structural dynamist at NASA’s Stennis Space Center, was awarded as an ECI grant in 2015. After initial proof of concept and a preliminary design review, the HiDyRS-X project was placed within NASA’s Game Changing Development program to complete its first prototype. Created in partnership with Innovative Imaging and Research Corporation, the project was tested on small rocket nozzle plumes at Stennis.
The massive booster test served as a rare opportunity to test the HiDyRS-X hardware in a full-scale environment. The Qualification Motor 2, or QM-2, test was held at Orbital ATK’s test facility in Promontory, Utah, and was the second and final booster test before SLS’s first test flight in late 2018. SLS will be the most powerful rocket in the world, and will take our astronauts farther into deep space than ever before.
In moving from the smaller-scale tests to QM-2, Conyers says the most difficult challenges were seen in compensating for brightness of the booster plume, which is several orders of magnitude brighter than what they had tested before. They were also faced with transporting and assembling the equipment at the QM-2 test site located in the desert of Utah — a remote environment requiring the HiDyRS-X team to be self-sufficient, as well as deliberate and methodical in their preparation and set up. Unlike the smaller scale rocket engine tests at Stennis, boosters are extremely powerful and, once ignited, cannot be turned off or restarted. The HiDyRS-X team had one shot at getting good footage.
In the days prior to the test of QM-2, the HiDyRS-X team double- and triple-checked their connections and start procedures to allow the camera to collect as much footage as possible. Leading up to the day of the test, the team performed several more dry runs using the camera to ensure that everything was working perfectly, Conyers says.
With thousands of people assembled over a mile away to watch the fiery plume of the solid rocket booster, Conyers and his team monitored the camera from a safe distance, ready to act in case something went wrong. As the countdown clock ticked down to zero, the SRB ignited and the HiDyRS-X team watched the camera’s automatic timer fail to go off. Luckily, they were quick to hit the manual override, allowing the camera to turn on just moments after ignition.
Once engaged, the camera recorded several seconds of the two-minute test before the power source was suddenly disconnected. In an unanticipated series of events, the sheer power of the booster shook the ground enough for the power cable to be removed from the power box.
Having had two unexpected camera outages during the test, Conyers described being disappointed.
“I was bummed,” Conyers says. “Especially because we did not experience any failures during the dry runs.”
When the team reviewed the camera footage, they saw a level of detail on par with the other successful HiDyRS-X tests. The team saw several elements never before caught on film in an engine test.
“I was amazed to see the ground support mirror bracket tumbling and the vortices shedding in the plume,” Conyers says. The team was able to gather interesting data from the slow motion footage, and Conyers also discovered something else by speeding up the playback.
“I was able to clearly see the exhaust plume, nozzle and the nozzle fabric go through its gimbaling patterns, which is an expected condition, but usually unobservable in slow motion or normal playback rates.”
Although initially disappointed with the camera anomalies, Conyers and the HiDyRS-X team came out of QM-2 with proof that their technology worked and that it had the ability to provide unprecedented views of high exposure rocket motor tests. The test experience also left Conyers with two major lessons learned for the future. First, to start the camera a full ten seconds before ignition to allow the ground team time to start the camera manually in the event of a timer failure. The second lesson, Conyers adds, is to understand just how powerful the engine tests are to properly protect and secure the electronics hardware from damage or disconnection.
“Failure during testing of the camera is the opportunity to get smarter,” Conyers says. “Without failure, technology and innovation is not possible.”
HiDyRS-X will continue testing at Stennis, while a second prototype of the camera is built with more advanced high dynamic range capabilities, using data gathered from the past few years of experimentation. The second HiDyRS-X prototype will be made with an improved manufacturing process to enhance the alignment capabilities of multiple exposure settings -- a challenge overcome in the first prototype.
HiDyRS-X not only stands as a game changing technology expected to revolutionize propulsion video analysis, but it also stands as a testament to ECI and the power of determined young engineers within NASA. Seasoned NASA employees and recent hires alike have the capacity to significantly contribute to NASA’s research and development goals. ECI’s emphasis on pairing young engineers with innovative industry partners enables technological leaps that would otherwise be impossible.
“The Stennis HiDyRS-X ECI project continues to be an exciting and challenging public-private collaboration of which we are proud to be a part,” says Mary Pagnutti, president of the Innovative Imaging and Research Corporation. “It’s giving us the chance to mentor early career technologists and advance the way we image and assess rocket motor firings.”