NASA Partners with Elementum 3D, RPM Innovations

Elementum 3D, a developer and supplier of metal additive manufacturing (AM) advanced materials, print parameters, and services, is collaborating with RPM Innovations, Inc. as part of NASA’s RAMFIRE (Reactive Additive Manufacturing for the Fourth Industrial Revolution) project, designed, printed and tested a new additively manufactured rocket nozzle made from the company’s A6061-RAM2 aluminum powder.

In October 2023, at the Marshall Space Flight Center, NASA performed 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 temperature gradients up to 6000 °F.

This 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. 

The aerospike design breaks free from the traditional design, which is efficient at only one point in the rocket’s trajectory.

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 efficient engine performance, 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.

The aerospike nozzle configuration presents design and fabrication challenges. This has 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.

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 step toward developing a larger version.

NASA commissioned Elementum 3D to work closely with its RAMFIRE project engineers and scientists and RPM Innovations, to develop and print a 36-in.-diameter aluminum aerospike rocket demonstration nozzle out of Elementum 3D’s A6061-RAM2 material. RPM Innovations performed the build with its large-format LP-directed energy deposition 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.

Sources: Press materials received from the company and additional information gleaned from the company’s website.