A System Engineering Approach to Assess the Benefits of Additive Manufacturing for Rocket Engines

Advancements in manufacturing techniques, such as additive manufacturing (AM), have opened new possibilities in the aerospace industry, particularly in launch vehicle propulsion systems. Companies such as Relativity Space, SpaceX, Rocket Lab, and Blue Origin are taking advantage of the cost and lead-time benefits of AM for rocket engine production and development. However, the viability of utilizing AM for legacy rocket engine upgrades is in the early stages of development and would require the upgraded parts be recertified which is time consuming and expensive. For instance, the R5-2S, formerly known as Space Shuttle Main Engine, will power NASA's Space Launch System (SLS); however, to meet NASA's future demand for these engines, production must be restarted. Considering NASA's increased interest in outer planetary missions to Mars and beyond, it is also advantageous to explore the benefits of AM for other game changing propulsion systems such as Nuclear Thermal Propulsion (NTP) engines. Due to the evolving nature of the AM technology, the suitability of AM for flight-proven RS-25s or NTP engine development is still in question. It is also important to address whether AM can be effectively used for legacy engine designs or if it's better applied in clean-sheet designs. Consequently, there is a need for a structured evaluation methodology for rocket engine parts to provide guidance on AM decisions for rocket engine upgrades and development. This study will demonstrate one such methodology by using future production of the RS-25s and development of the NTP engine as design examples. This methodology will qualitatively consider different aspects of the decision-making process of AM utilization on a part-by-part basis. The different parameters contributing to the decision will be evaluated utilizing a Systems Engineering (SE) trade study approach of weighing system parameters. The methodology of this study will be represented in the Systems Modeling Language (SysML). This will allow for traceability and assess the utility of Model Based Systems Engineering (MBSE) for establishing an affordability framework for rocket engine development. This methodology is intended to be continuously improved as more empirical data is generated from AM and rocket engine development, improving its effectiveness as a decision-making tool.