ERIE, Colo., July 25, 2024 /PRNewswire-PRWeb/ — Elementum 3D, a leading developer and supplier of metal additive manufacturing (AM) advanced materials, print parameters, and services, is pleased to share that, collaborating with RPM Innovations, Inc. as part of NASA’s RAMFIRE (Reactive Additive Manufacturing for the Fourth Industrial Revolution) project, designed, printed, and successfully tested a new additively manufactured rocket nozzle made from the company’s A6061-RAM2 aluminum powder. This breakthrough advances ongoing efforts to exceed current rocket performance and efficiency.
In October 2023, at the Marshall Space Flight Center, NASA performed what some thought was impossible: a successful hot-fire test of an additively manufactured aluminum rocket nozzle. The NASA-funded Reactive Additive Manufacturing for the Fourth Industrial Revolution (RAMFIRE) project’s goal was to transition rocket engine technology to a laser powder-directed energy deposition (LP-DED) process to enable large-scale production. The prior approach used lightweight, additively manufactured aluminum alloys printed with a laser-powder bed fusion (L-PBF) process capable of experiencing huge temperature gradients up to 6000 °F.
This breakthrough supports efforts to make large-scale nozzles, including aerospikes, available to industry. This successful project positive result allows aerospace/space engineers to see the nozzle as proof-of-concept that informs new component designs.
This breakthrough supports efforts to make large-scale nozzles, including aerospikes, available to industry. The RAMFIRE project printed a large-scale LP-DED aerospike demonstration nozzle with integral channels made of Elementum 3D’s A6061-RAM2. This successful project positive result allows aerospace/space engineers to see the nozzle as proof-of-concept that informs new component designs.
For nearly seven decades, rocket engineers have sought an alternate design to the standard bell-nozzle rocket engine. The aerospike design breaks free from the traditional design, which is efficient at only one point in the rocket’s trajectory.
Why is this innovative nozzle a sought-after option, especially since the bell nozzle is a proven design with adequate capabilities throughout the history of human spaceflight?
The aerospike’s inside-out rocket nozzle plume travels externally, rather than exiting from within a traditional bell-shaped nozzle. The main advantage is that, as the rocket climbs, atmospheric and airstream pressure keep the plume at optimum conditions along the entire trajectory. This allows highly efficient engine performance, including better performance over a range of pressures and altitudes, delivering higher payloads while decreasing overall rocket weight.
If rocket launches are more efficient using the aerospike nozzle design, why has it never been seriously tested on the launchpad?
The lack of actual flight test data has precluded use of these nozzles in current as well as next generation space launch vehicles.
Moreover, the aerospike nozzle configuration presents unique design and fabrication challenges. This and other factors have meant limited test opportunities and a dearth of actual flight test data, precluding use of the aerospike design on current and next generation launch vehicles.
Additive manufacturing has changed perspectives about the ability to test and implement the aerospike design in a cost-effective manner. NASA recently validated data from hot-fire tests on their 3D printed Rotating Detonation Rocket Engine (RDRE), which is not a traditional combustion engine, and reported that recent advancements in 3D printing can overcome some of the engine’s design challenges—specifically, how to manage its temperature. The ability to print the aerospike demonstration nozzle with a qualified high-strength, lightweight aluminum alloy is a significant step toward developing a larger version.
NASA commissioned Elementum 3D to work closely with their RAMFIRE project engineers and scientists and RPM Innovations, Inc., to develop and print a 36″-diameter aluminum aerospike rocket demonstration nozzle out of Elementum 3D’s A6061-RAM2 material. RPM Innovations performed the build with its large-format LP-DED process. DED uses a focused energy source to create 3D printed parts with powder or wire feedstock. With DED, metal deposition and fusion occur simultaneously. A nozzle deposits material into the focused beam of a high-power laser under tightly controlled atmospheric conditions. The feedstock melts and deposits as the tool path progresses.
REM Surface Engineering supported the RAMFIRE project’s post-production with its Extreme ISF Process. They uniformly removed ~400 µm of surface material from the aerospike nozzle surface, which reduced surface roughness/waviness and hot-wall thickness. The benefits of improving the hot wall surface texture include extending the nozzle’s fatigue life and creating a more uniform surface for heat transfer/heat pickup properties. The wall thickness reduction can also bring DED parts into final geometric tolerances. While not performed on this unit, internal channel finishing for rocket nozzles and similar components can reduce particle shedding and pressure drop caused by as-printed roughness.
Why has it taken almost 70 years to successfully produce a lightweight, high-strength aluminum rocket engine?
For one thing, the design requires conformal cooling channels to flow cryogenic propellants that keep the nozzle well below the material’s melting temperature. Internal channels are an additive manufacturing specialty and are far too complex to create with traditional machining processes.
Second, metal additive manufacturing via laser melting processes only became industrialized in the past few decades as computer, automation, and laser technology grew more sophisticated and affordable.
Finally, the ability to additively manufacture aerospace-grade aluminum has only become possible in the past decade. Since 2014, Elementum 3D has gained extensive knowledge and experience developing “impossible-to-print” high-strength aluminum feedstock powders with its patented RAM (Reactive Additive Manufacturing) technology.
Standard aluminum alloys are highly prone to a type of cracking called hot tearing under the rapid heating and cooling conditions inherent to laser welding processes. Industry considers popular wrought aluminum alloys, including AA6061, un-weldable for this reason. Elementum 3D’s RAM chemistry controls the solidification process, producing crack-free, fine-grained microstructures and printed material with strength equal–and in some cases superior–to wrought aluminum.
Will the combination of A6061-RAM2’s optimized thermal and mechanical properties and the design freedom of additive manufacturing be the path to designing and manufacturing new, innovative rocket engines that rival the efficiency of an aerospike rocket engine?
Only time and further research can answer that question. The research data acquired from optimizing A6061-RAM2 aluminum alloy for large blown-powder DED improves engineers’ confidence in the ability to improve rocket efficiency to meet or exceed the aerospike’s performance.
