NASA is constantly bringing additive manufacturing into use on projects, whether it’s 3D printing rocket engine parts or launching 3D printed CubeSats into space. For several years, NASA has been working on a project involving building a completely 3D printed rocket engine. It won’t culminate in an engine that will actually go into space; rather, the goal is to show that 3D printing an engine can be done and that it could be done again in the future, changing the way that rocket engines are made and saving money, time, and resources.
The Low Cost Upper Stage-Class Propulsion Project involves using additive manufacturing to develop high-pressure/high-temperature combustion chambers and nozzles with copper alloys. In its latest development, NASA successfully hot-fire tested a combustion chamber, made using a new combination of 3D printing techniques, at the agency’s Marshall Space Flight Center in Huntsville, Alabama. The project is a joint effort between Marshall, Glenn Research Center in Cleveland, Ohio, and Langley Research Center in Hampton, Virginia.
“NASA continues to break barriers in advanced manufacturing by reducing time and costs involved in building rocket engine parts through additive manufacturing. We are excited about the progress of this project. We demonstrated that the E-Beam Free Form Fabrication produced combustion chamber jacket can protect the chamber liner from the pressures found in the combustion chamber,” said John Fikes, Project Manager for the Low Cost Upper Stage-Class Propulsion Project.
In 2015, NASA 3D printed the first-ever full-scale copper rocket engine part, a combustion chamber liner 3D printed at Marshall from a powdered copper alloy made by material scientists at Glenn. The combustion chamber liner was then sent to Langley, where E-Beam Free Form Fabrication Technology, a layer-additive process that uses an electron beam and wire to create metal structures, was used to deposit a nickel alloy onto the liner, forming the chamber jacket.
A copper lining is good for thermal conductivity, but it’s not very strong, hence the nickel alloy jacket, which strengthens it so that it can withstand the pressure contained in the chamber. This process eliminates the need for traditional techniques like brazing, meaning that the jacket could be made in hours rather than days or weeks. In addition, traditional processes would have required multiple welded parts, while E-Beam Free Form Fabrication Technology allowed it to be made in one piece.
The chamber was recently sent back to Marshall where it was installed in a test stand and fired at various power levels for durations of 2 to 30 seconds under conditions resembling an actual launch. The final test ran for a duration of 25 seconds under 100 percent power, and the chamber remained in great shape according to post-test data.
“Testing the chamber in flight-like conditions helps us continue to prove these revolutionary technologies. We are proud of the way the chamber preformed during this test and the capabilities here at Marshall that allow us to continue paving the way for advancements in additive manufacturing,” said Chris Protz, Engineering and Design Lead for the propulsion project.
The technology for the combustion chamber liner and its jacket will be incorporated into a new project called Rapid Analysis and Manufacturing Propulsion Technology, which aims to further improve production times and costs for thrust chamber assemblies.
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