NASA, an independent agency of the U.S. federal government responsible for the civil space program, aeronautics research, and space research, recently built and tested an innovative 3D printed rocket nozzle made of aluminium, making it lighter than conventional nozzles and paving the way for deeper space flights with greater payload capacity.
Engineers from NASA’s Marshall Space Flight Centre in Huntsville, Alabama, collaborated with Elementum 3D in Erie, Colorado, under the agency’s Announcement of Collaborative Opportunity, to develop a weldable type of aluminium that is heat resistant enough for use on rocket engines. Aluminium has a lower density than other metals, allowing for high-strength, lightweight components.
However, due to its low tolerance to extreme heat and proclivity to crack during welding, aluminium has traditionally been avoided for additive manufacturing of rocket engine parts – until now.
RAMFIRE Project
RAMFIRE (Reactive Additive Manufacturing for the Fourth Industrial Revolution) project, which is funded by NASA’s Space Technology Mission Directorate (STMD), focuses on developing lightweight, additively manufactured aluminium rocket nozzles. Small internal channels in the nozzles keep the nozzle cool enough to prevent melting.
A nozzle may require up to a thousand individually joined parts using traditional manufacturing methods. The RAMFIRE nozzle is constructed as a single piece, resulting in fewer bonds and a shorter manufacturing time.
NASA and Elementum 3D first created the A6061-RAM2 aluminium variant to construct the nozzle and modify the powder used with laser powder directed energy deposition (LP-DED) technology. Another commercial partner, Rapid City, South Dakota-based RPM Innovations (RPMI), used the newly invented aluminium and specialised powder to build the RAMFIRE nozzles using their LP-DED process.
Paul Gradl, RAMFIRE principal investigator at NASA Marshall, said, “Industry partnerships with specialty manufacturing vendors aid in advancing the supply base and help make additive manufacturing more accessible for NASA missions and the broader commercial and aerospace industry.”
We’ve reduced the steps involved in the manufacturing process, allowing us to make large-scale engine components as a single build in a matter of days.
– Paul Gradl, RAMFIRE Principal Investigator, NASA Marshall
Aluminium 3D Printed Rocket Nozzle
NASA’s Moon-to-Mars goals necessitate the ability to transport more cargo to deep space destinations. The novel alloy could help with this by allowing the production of lightweight rocket components that can withstand high structural loads.
“Mass is critical for NASA’s future deep space missions. Projects like this mature additive manufacturing along with advanced materials, and will help evolve new propulsion systems, in-space manufacturing, and infrastructure needed for NASA’s ambitious missions to the Moon, Mars, and beyond.”
– John Vickers, principal technologist for STMD advanced manufacturing
Earlier this summer, two RAMFIRE nozzles completed multiple hot-fire tests using liquid oxygen and liquid hydrogen fuel configurations, as well as liquid oxygen and liquid methane fuel configurations, at Marshall’s East Test Area. The nozzles successfully accumulated 22 starts and 579 seconds, or nearly 10 minutes, of run time with pressure chambers exceeding 825 pounds per square inch (psi), which was higher than anticipated testing pressures. This event demonstrates that the nozzles can function in the most extreme deep-space environments.
“This test series marks a significant milestone for the nozzle,” Gradl said. “After putting the nozzle through the paces of a demanding hot-fire test series, we’ve demonstrated the nozzle can survive the thermal, structural, and pressure loads for a lunar lander scale engine.”
Aside from successfully building and testing rocket engine nozzles, the RAMFIRE project has used the RAMFIRE aluminium material and additive manufacturing process to build other advanced large components for demonstration purposes. A 36-inch diameter aerospike nozzle with complex integral coolant channels and a vacuum-jacketed tank for cryogenic fluid applications are among the features.
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