How do you determine what parts will be made of what materials?
ATK performs trade studies as a part of the initial program or product lifecycle to determine the materials that will be utilized on a part or component; typically a composite versus metal trade. In most instances, the composite design costs more to produce than the metal counterpart. However, the composite design typically saves weight and has the potential to reduce part count. The trade studies take into account the specific criteria for the component and weight, each based on customer need. Some customers or applications will pay a higher price for weight savings or increased performance (examples include space craft and satellite structures), while others may place a higher priority on cost (such as commercial aircraft or automotive structures). ATK also considers how the individual part or component must interface with other components and in the overall system.
How did you become involved with NASA’s Ares I launch vehicle?
ATK worked on a trade study with NASA comparing the base-line approach of metal to the attributes of composites. Our design and analysis group focused its efforts on some of the major Ares I first stage components, such as frustum and aeroshell as well as skirts. The results demonstrated the use of composites structures could result in a component weight savings of 25 to 30 percent when compared to similar components made from metal. These trade studies were evaluated by ATK and presented to NASA. As a result, the frustum and aeroshell were chosen to be manufactured from composites.
How do you see the new NASA CCM (composite crew module) reducing overall weight of future manned launch vehicles?
The CCM project has demonstrated the capabilities of composites in the application of a pressure shell for a manned spacecraft. When a composite structure design is optimized for its intended application, you will typically realize a 15 to 20 percent weight savings over an equivalent metal structure. We believe that what was demonstrated on the CCM project can be applied to an overall integrated crew module or cargo module assembly, and will realize the same levels of weight savings over an all-metallic design.
From ATK’s point of view, how would you describe the outcome of the CCM project?
The CCM project was hugely successful for NASA, ATK and all of the industry partners that had the opportunity to support this project. One of NASA’s primary objectives was to provide the agency with experience in the design, manufacture and test of complex composite structures. The other primary objective was to test and validate the design assumptions and manufacturing processes. From both perspectives, this project was a home run. The CCM completed all testing, which included cycled structural loading and internal pressurization, to design ultimate limits—with no failures. Additionally, intentional damage was induced to the pressure shell and testing to ultimate loads repeated and no failures or damage propagation were detected. That’s a significant result, as it demonstrates the integrity of composites in support of manned space flight.