NASA has recently conducted a test of a 3D printed aluminum rocket nozzle.

 

The RAMFIRE nozzle performs a hot fire test at Marshall’s East test area stand 115. Credit: NASA

In the realm of current space exploration, a significant trend revolves around how emerging technologies and procedures are driving down the expenses associated with sending crews and payloads into space. This trend extends beyond the commercial space sector and the evolution of retrievable and reusable rockets, as space agencies are also devising innovative approaches to enhance the affordability and accessibility of space. Notably, NASA has been at the forefront of these efforts, recently accomplishing a milestone in manufacturing by producing an aluminum rocket engine nozzle through their groundbreaking Reactive Additive Manufacturing for the Fourth Industrial Revolution (RAMFIRE) process.

Additive manufacturing (AM), more commonly referred to as 3D printing, has instigated a revolution in the world of manufacturing. Unlike conventional machine-based production, which involves shaping items from raw materials and discarding unused materials, 3D printing constructs customized components from the ground up. This manufacturing technique generates minimal waste and offers unparalleled speed, cost-efficiency, and effectiveness when compared to traditional methods. While its early applications were primarily limited to modeling and prototyping, 3D printing has substantially expanded its scope in recent years, particularly within the aerospace industry.

The creation of the aluminum nozzle was a collaborative endeavor between NASA's Announcement of Collaborative Opportunity and the leading AM company, Elementum 3D. Elementum 3D, headquartered in Erie, Colorado, specializes in research related to metal alloy additive manufacturing, as well as the development of materials and printing processes, and the scaling of production techniques. Notably, in 2020, the company was selected as part of NASA's Announcement of Collaborative Opportunity to produce a weldable form of aluminum with sufficient heat resistance for utilization in rocket engines. This achievement led to the development of the aluminum variant, known as A6061-RAM2.

The RAMFIRE nozzle performs a hot fire test at Marshall’s East test area stand 115. Credit: NASA

Compared to other metals, aluminum offers a lower density, making it suitable for high-strength, lightweight components. However, traditional manufacturing methods require assembling a rocket nozzle from numerous individual parts, which proves impractical for aluminum due to its low tolerance for extreme heat and a propensity to crack during welding. The RAMFIRE process, funded by NASA's Space Technology Mission Directorate (STMD), overcomes these challenges by producing aluminum components as single, integrated pieces. This approach reduces the need for extensive bonding and significantly shortens the manufacturing time.

Moreover, these nozzles are designed with small internal channels to effectively dissipate heat and prevent melting. The RAMFIRE 3D printer and its associated process were developed by RPM Innovations (RPMI), a company based in South Dakota specializing in Directed Energy Deposition (DED). RPMI's method involves depositing and fusing layers of powdered alloy using lasers. When combined with Elementum 3D's specialized aluminum powder, this process is referred to as laser powder-directed energy deposition (LP-DED).

During the recent summer, two RAMFIRE nozzles underwent a series of hot-fire tests at the Marshall Space Flight Center's East Test Area in Huntsville, Alabama. These nozzles performed admirably using various fuel configurations, including liquid oxygen (LOX) and liquid hydrogen (LH2), as well as LOX and liquid methane. Notably, they withstood pressures exceeding 5690 kilopascals (825 psi), which are higher than typical launch conditions. The nozzles successfully completed 22 start tests and operated continuously for nearly 10 minutes, demonstrating their capability to function effectively in the most demanding deep-space environments. According to Paul Gradle, the RAMFIRE principal investigator at NASA Marshall, this achievement marks a significant advancement in rocket nozzle technology, as stated in a NASA press release.

In March 2023, NASA demonstrated the effectiveness of 3D-printed components when Relativity Space test-launched their Terran 1 rocket from Cape Canaveral Space Force Station in Florida. This test rocket was groundbreaking as it was the first to be entirely composed of 3D-printed parts, including nine engines made from an innovative alloy called Glenn Research Copper (GRCop). These engines were additively manufactured at NASA's Glenn Research Center under the agency's Game Changing Development program, and they exhibited the ability to withstand temperatures reaching up to 3,315 °C (6,000 °F), which is approximately 40% higher than traditional copper alloys.

Moreover, in addition to rocket nozzles and engines, NASA's Rapid Additively Manufactured Feedstock for Rocket Engines (RAMFIRE) project also achieved the creation of a 91-centimeter (36-inch) diameter aerospike nozzle that includes components suitable for cryogenic fuel applications. These innovations are of great significance to NASA's Moon to Mars program, which encompasses Project Artemis, aiming to return astronauts to the Moon, and the development of the lunar infrastructure required to support crewed missions to Mars. An essential aspect of this program is the capability to transport larger payloads to destinations such as the Moon, Mars, and other deep-space locations.

By manufacturing lightweight rocket components that can endure higher structural loads and extreme temperatures, NASA has taken a significant step towards its goal of returning to the Moon with the intention of establishing a sustainable presence and ultimately sending astronauts to explore the surface of Mars. John Vickers, the principal technologist for STMD advanced manufacturing, emphasized the importance of these advancements in advancing NASA's missions.

NASA, ROCKETS, TECHNOLOGY, 3D PRINTING, 3D-PRINTED ROCKETS, ADDITIVE MANUFACTURING, FEATURED