In the current era, the use of new technologies and processes is reducing the cost to send crews and payloads into space. Space agencies are finding ways to make space accessible and affordable, beyond the commercial space sector. NASA is one of the space agencies that has recently tested and built an aluminum rocket engine using its new Reactive additive Manufacturing for Fourth Industrial Revolution (RAMFIRE).
3D Printing, or additive manufacturing (AM), has revolutionized the manufacturing industry. 3D-printing, in contrast to traditional machine-based production, creates components that are made-to order. This process produces virtually no waste, is cost-effective and efficient and can be done much faster than traditional methods. Whereas it was once confined to modeling and prototyping, the technology’s applications have expanded considerably in recent years – including the aerospace industry.
The aluminum nozzle was developed by NASA’s Announcement of Collaborative Opportunity in partnership with the leading AM company Elementum 3D. Elementum 3D is based in Erie Colorado and specializes in metal additive manufacturing research and development, as well as material and print processes. They also develop scaled-production techniques. The company was chosen in 2020 as part of a Collaborative Opportunity Announcement to develop a heat-resistant type of aluminum suitable for rocket engines. This led to the A6061 RAM2 aluminum variant.
Aluminum is lighter than other metals and has a higher density. This allows for lightweight, high-strength components. A rocket nozzle can require up to a thousand parts that are individually welded in conventional manufacturing. Aluminum has a very low tolerance for extreme heat, and it tends to crack when welded. The RAMFIRE process, which was funded under NASA’s Space Technology Mission Directorate (STMD), does away with this by producing aluminum components as a single piece, requiring far fewer bonds and significantly reduced manufacturing time.
In addition, they are equipped with internal channels to cool the nozzles enough to prevent melting. RPM Innovations, a commercial partner of RAMFIRE, developed the RAMFIRE process and 3D printer. This South Dakota company is a specialist in Directed Energy Deposition. Layers of powdered aluminum are deposited using lasers. When combined with Elementum 3D’s specialized aluminum powder, the resulting process is known as laser powder-directed energy deposition (LP-DED).
Earlier this summer, two RAMFIRE nozzles completed a series of hot-fire tests at the Marshall Space Flight Center’s East Test Area in Huntsville, Alabama. The nozzles were successful using both liquid hydrogen and liquid oxygen.2), as well as LOX and liquid methane fuel configurations, and at pressures exceeding 5690 kilopascals (825 psi) – higher than what is anticipated for launches. The nozzles completed 22 tests of start and continued to fire for almost 10 minutes. This proved that they could operate in even the most challenging deep-space environment. Paul Gradl is the RAMFIRE principal researcher at NASA Marshall. He said in a NASA Press Release:
“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. This test series marks an important milestone for nozzle. 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.”
NASA demonstrated the effectiveness 3D-printed parts in March 2023 by launching Relativity Space’s Terran 1 test rocket from Cape Canaveral Space Force Station, Florida. This rocket test was the first made entirely from 3D-printed components, and included nine engines made out of a new alloy called Glenn Research Copper. These engines were additively manufactured at NASA’s Glenn Research Center under the agency’s Game Changing Development program, and were able to tolerate temperatures approaching 3,315 °C (6,000 °F) – up to 40% higher than traditional copper alloys.
RAMFIRE manufactures rocket nozzles as well as engines. They also produce a 91 cm (36 inch) diameter aerospike with components that are used for cryogenic fuel. These innovations are crucial to NASA’s Moon to Mars program, which includes Project Artemis and returning astronauts to the Moon, and the creation of the lunar infrastructure necessary to mount crewed missions to Mars. The ability to send heavier payloads into deep space, including the Moon, Mars and other destinations, is fundamental to this program.
NASA is one step away from returning to the Moon permanently and putting boots on Martian ground by producing lightweight rocket components. John Vickers, STMD’s principal technologist, said:
“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.”
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