NASA NASA and satellite launch company Virgin Orbit have produced a usable 3D printed combustion chamber for rocket engines. The component is made of copper and is designed to drive the adoption of 3D printing in commercial space and reduce the cost of future NASA missions.
Founded in 2017, Virgin Orbit has been working with NASA's Combustion and Additive Manufacturing experts for the past two years at the Marshall Space Flight Center (MSFC) in Alabama and other centers in Cleveland and California.
As part of the ongoing development process, the latest 3D printed combustion chamber successfully completed a test launch of MSFC, which can provide up to 2,000 pounds of thrust.
The combustion chamber is a key component of all rocket engines. Here the propellant is mixed and ignited, producing extremely high temperatures up to 5,000 ° F (2760 ° C).
This requires complex internal cooling channels that are filled with gas that cools below 100 ° F (38 ° C) above absolute zero. The complex cooling process makes the combustion chamber one of the most difficult engine components to develop, while maintaining low costs and lead times.
According to Paul Gradl, senior engineer at NASA and project leader at Virgin Orbit, "Traditionally, manufacturing, testing and delivering traditional combustion chambers took months. We can significantly reduce this time."
"Additive manufacturing is ready to add and improve traditional processes. It provides new design and performance opportunities, and provides a highly durable hardware-through this partnership, we have further enhanced this capability."
This project adds design complexity and also faces the challenge of 3D printed multi-metal copper components. Copper is of particular interest to the aerospace industry due to its high thermal conductivity, excellent creep (deformation) and high temperature strength, and economy. However, due to its natural sheen, copper has proven to be a difficult material for additive manufacturing because it reflects the heat applied by the laser beam.
Nevertheless, some aerospace companies have successfully used copper-based alloys to produce parts. Private space exploration company Aerojet Rocketdyne showed off its copper-based SLM-made RL-10 rocket thrust chamber in 2017. Aerospace startup Launcher successfully tested the EOS 3D printed copper rocket engine in 2018. NASA also had some a priori successes with the material, 3D printing the first full-size copper rocket engine of 2015.
To create the multi-metal combustion chamber, Virgin Orbit engineers used the proven NASA additive manufacturing copper alloy GRCop-84, which was developed in 2014 for alignment inside the chamber. It was then printed on a Virgin Orbit hybrid additive / subtractive all-in-one machine that applied a second bimetal superalloy jacket and processed the parts to the correct size.
Earlier this year, NASA researchers announced the development of GRCop-84, the ultimate replacement for GRCop-42. The high-strength, high-conductivity copper-based alloy was created by a team from NASA MSFC and the NASA Glen Research Center (GRC) in Ohio. It is hoped that GRCop-42 will have higher thermal conductivity while matching the strength of GRCop-84.
The benefit of developing multi-metal parts is that you can take advantage of the unique properties of each metal, such as strength or thermal conductivity, to create a stronger, higher-performance end product.
Commenting on the addition of different metals, Kevin Zagorski, advanced manufacturing manager at Virgin Orbit, said: "The combination of multiple optimized materials and additive manufacturing technologies we use represents a significant advance in 3D printed rocket engine combustion chambers."
"The information we get from working with NASA will be key to applying these technologies," he added.
The combustor was tested using high-pressure liquid oxygen / kerosene propellants in late 2018 / early 2019, producing more than 2,000 pounds of thrust in a series of 60-second ignition tests.