Additively Manufactured Bimetallic Combustion Chambers for Small Launch Vehicles

Arctic Slope Technical Services, Inc. (ASTS) is pleased to propose to continue the development of an additive manufacturing (AM) approach for fabricating bimetallic combustion chambers. Our chamber design, which is applicable to future NASA small launch vehicles, exploits the combined capabilities of selective laser melting (SLM) and magnetic pulse welding (MPW), in order to reduce manufacturing lead time and cost and to improve quality through ease of inspection. The chamber will use a two-piece GRCop-84 liner that is inserted and MP welded into a one-piece Inconel 625 structural jacket. The MPW step will be used to permanently join the two halves of the liner at the throat and the liner itself to the jacket in a structurally sound, watertight manner. Our structural jacket design includes integral propellant manifolds, which eliminates the time and expense associated with machining or casting separate components and welding them in place.The benefits of such a design are substantial. First, it is well understood that for complicated components like a modern combustion chamber, an AM manufacturing approach can drastically reduce cost (by 50% or more) and lead time (weeks instead of months). Second, our particular design overcomes weaknesses of other additive designs by enabling easy inspection of the printed parts that otherwise would have to undergo CT scanning or X-ray inspection, which has proven to be exceptionally difficult for complex internal geometries like regenerative cooling channels and propellant manifolds. Third, our basic material and manufacturing approach is scalable to booster class combustion chambers at a rate controlled solely by scaling of the build volumes available in commercial SLM machines (which is occurring rapidly). In fact, commercial MPW systems are already being used in the automotive industry that can instantaneously weld parts of several meters in length