Photo credit: www.nasa.gov
Nasa’s Stennis Space Center: A Legacy of Innovation in Rocket Propulsion Testing
NASA’s Stennis Space Center, located near Bay St. Louis, Mississippi, is recognized as the largest rocket propulsion test facility in the United States. For over 35 years, it has played a crucial role not only in testing but also in training engineers, particularly during a significant period in the late 1980s and early 1990s when it served as a vital learning hub for enhancing the space shuttle main engines.
Between 1988 and the mid-1990s, engineers at Stennis operated a Diagnostic Test Facility dedicated to rocket engine plume exhaust diagnostics. This endeavor sought to deepen the understanding of the combustion processes within the space shuttle main engines, setting a foundation for advanced research and testing practices that continue at the center today.
“The work conducted at the Diagnostic Test Facility demonstrates the proactive and dedicated ethos of the NASA Stennis team to bolster the nation’s space exploration initiatives,” remarked Joe Schuyler, director of the NASA Stennis Engineering and Test Directorate.
Joe Schuyler
NASA Stennis Engineering and Test Directorate Director
Visualize a rocket lifting off, trailing behind it a vivid stream of exhaust, referred to as the engine plume. This plume is indicative of various conditions within the engine, including the state of its materials subjected to the extreme high temperatures of combustion. Just like a physician assesses vital signs during an examination, engineers needed to interpret the plume emitted by the space shuttle main engines to ensure their operational integrity for future missions.
The Stennis Space Center, being the premier facility for propulsion testing in the country, was an ideal venue for such detailed studies. Thus, the project aimed at analyzing space shuttle main engine exhaust was initiated by Stennis engineers in collaboration with NASA.
The vision for the Diagnostic Testbed Facility was conceived in October 1987. Following a rapid five-month design phase, construction began to create a space roughly the size of a standard garage intended for in-depth research on rocket engine exhaust and the associated material degradation observed during hot fire tests.
The facility was outfitted with a 1,300-square-foot control center and a rooftop observation deck, along with small-scale testing infrastructure to evaluate a 1,000-pound-thrust rocket engine that functioned similarly to the larger engines used in actual shuttle missions. This utilization of a smaller engine allowed for increased flexibility in testing while incurring lower costs than if they had operated the full-size space shuttle engine.
Multiple short-duration hot fire tests could be executed efficiently with the smaller engine, which produced data from exhaust temperatures soaring to 3,900 degrees Fahrenheit within just six seconds. For each test, chemical solutions replicating engine materials were introduced into the combustion chamber, afterward analyzed for color emissions using various optical and data collection tools.
This systematic analysis enabled identification of specific wear patterns within engine components, mirroring the diagnostic practices used in medical assessments to determine necessary maintenance interventions.
Glenn Varner
NASA Stennis Engineer
The importance of the Diagnostic Testbed Facility extended beyond the immediate testing protocols, establishing critical safety measures for engine operations while simultaneously enriching the engineers’ understanding of exhaust diagnostics. Engineers aimed for swift turnaround times between tests, averaging 18 to 20 minutes, with a record-setting minimum of 12 minutes between tests. By January 1991, the facility had achieved 588 engine firings, accumulating over 3,450 seconds of operational data.
As testing advanced, the facility’s team developed extensive expertise in plume diagnostics. Among them was Glenn Varner, a longtime engineer who played an integral role in successful testing efforts for NASA’s Space Launch System (SLS) core stage. Much of Varner’s foundational knowledge stemmed from experiences gained at the Diagnostic Test Facility, emphasizing the broad learning opportunities it provided in crucial areas like handling propellants and engine components.
The impact of the Diagnostic Testbed Facility reached far beyond those directly involved in its research efforts. In 1993, following upgrades, the facility completed a series of successful tests on a small-scale liquid hydrogen turbopump for a commercial aerospace custome, marking an early instance of collaboration between NASA and the private sector. This partnership set a precedent for the ongoing success of the NASA Stennis E Test Complex, which now accommodates numerous commercial aerospace projects using its advanced infrastructure and skilled propulsion experts.
“Although the original structures related to the Diagnostic Testbed Facility are largely unrecognizable today, the innovative spirit that characterized that time remains vibrant at Stennis,” Schuyler stated.
Over the past two decades, NASA Stennis has effectively harnessed the technological advancements and insights derived from the Diagnostic Test Facility to bolster both its missions and industry collaborations.
The facility’s equipment and testing methodologies have been integral to developing the E Test Complex, which features twelve active test cell positions capable of conducting various propellant and engine tests.
“The Diagnostic Testbed Facility laid the groundwork for what we have now,” said Varner. “The foundational elements from that time still inform our testing methodologies today, with many of the personnel who developed their skills there now guiding new engineers in managing the complexities of propulsion systems.”
This legacy of knowledge transfer and practical application ensured that the methodologies born from the Diagnostic Testbed Facility continue to shape the future of propulsion testing and development at NASA Stennis.
Source
www.nasa.gov