During the original Apollo program, NASA produced more than 650 thrusters to support six Moon landings. In fact, each Apollo Lunar and Service module featured four “quad” reaction control systems (RCS), each of which generated more than 100 pounds of thrust to control the spacecraft’s roll, pitch, and yaw during flight.
While these feats of engineering propelled those early, critical missions, those applications are now 60 years in the past. As we look forward, NASA’s Artemis program aims to place unmanned Orion spacecraft into lunar orbit, with the eventual goal to achieve crewed landings on the Moon, which would then serve as a launching point for Mars exploration.
Aerojet Rocketdyne’s Unique Challenge
The quad RCS was a milestone at its initial creation, but to reiterate, 60 years of innovation in space exploration can alter perspectives of once cutting-edge designs. Aerojet Rocketdyne looked to improve upon the original RCS, adapting its design to reduce weight and improve material qualities without sacrificing the design complexity that defined the original iteration.
Fortunately, in those 60 years of innovation, the strides made in advanced metal additive manufacturing (AM) could enable the improvement of core parts with unprecedented efficacy. To achieve their goals, Aerojet Rocketdyne engaged nTopology for design and modeling improvements to the RCS, and Velo3D to execute on those designs.
In evaluating potential manufacturing partners, Aerojet Rocketdyne ran into issues with both traditional manufacturing methods and conventional metal AM systems. For traditional manufacturing such as casting, brazing, and welding, the required complexity of the internal channels were all but impossible to accomplish given the levels of post-processing required.
Conventional metal AM systems struggled with the part’s delicate lattice features, used to increase stiffness, and would subject the build to recoater contact which in turn threatened part integrity. These systems also required pitching the build plate for manufacturing which not only warped the final part, but additionally required extensive support structures which would need to be extracted in post-processing.
The Velo3D and nTopology Solution
With a clear mandate of part optimization, weight reduction, and improved material quality, all while remaining cost-conscious, Velo3D and nTopology got to work.
Working with nTopology and Velo3D, Aerojet Rocketdyne combined the latest advancements in design software technology and the Velo3D end-to-end manufacturing solution, with scalable hypergolic MON-25 propulsion technology, to create a high-performance quad RCS at a fraction of the production cost of legacy RCS designs.
“As with any complex endeavor, the more affordable you can make it, the greater the chance that you will ensure its completion, and the moon is no different,” said James Horton, Aerospace Engineer and Mission Architect at Aerojet Rocketdyne. “Metal AM plays a key role in achieving these goals.”
Velo3D printed the part using Inconel® 718, a nickel-based alloy, which provided a marked alternative to the original quad injector’s Titanium 6Al-4V, notorious for printing hard and brittle.
Utilizing Velo3D’s Sapphire printers, Aerojet Rocketdyne was able to achieve optimized, complex internal lattice design features without the need for extensive support structures or pitched build plate warping.
In the end, Aerojet Rocketdyne was left with an RCS thruster that is 1/5 the mass, 1/2 the size, and 1/3 the cost of a conventionally manufactured version. It also contains far fewer components thanks to design insight from nTopology, making it easier to assemble, with much less chance of failure during operation.
Aerojet Rocketdyne Mark II injector block in different orientations. The part is comprised of Titanium 6AI-4V and was printed on a Velo3D Sapphire metal 3D printer.
As we look to the future of space exploration, a good place to start is improving and optimizing the innovations of the past. By tapping the potential of cutting-edge modern-day design and manufacturing solutions, Aerojet Rocketdyne was able to breathe new life into their quad RCS and ready it for the future.
