Design-to-Cost and Robust Liquid Rocket Engine Design Using PMDA/PMDO and MBSE

Abstract

Prevailing launch vehicle and liquid rocket engine design philosophies derived from 1950s research efforts focus on delivering optimum performance and minimizing weight. Performance optimization has been sought on almost every major booster and upper stage engine typically requiring rocket propulsion technologies that push the components to their technological limits. An alternate design philosophy of “design-to-cost”, while often discussed, has historically seen limited use in conceptual design studies. Taking material limits, transients, component margins, and manufacturability into account earlier in the rocket engine design process can potentially produce simpler designs that suboptimize on traditional performance parameters (weight and performance) but yield more robust designs that cost less to manufacture. Two emerging analytical philosophies can evolve the design-to-cost approach. Integrated system models using Preliminary Multidisciplinary Analysis/Preliminary Multidisciplinary Optimization (PMDA/PMDO) optimize engine configurations using material and component operation constraints on the aforementioned parameters to achieve a robust design. PMDA/PMDO based models create a medium for all engineering disciplines to effectively communicate and explore constraint-based design options from the earliest phases of product development. The second component of the rocket engine evolved “design-to-cost” philosophy uses Model Based Systems Engineering (MBSE). MBSE is the formalized application of modeling to support system requirements, design, analysis, verification and validation activities beginning in the conceptual design phase and continuing throughout development and later life cycle phases. This is an approach where models are an integral part of the technical baseline throughout the life cycle. At the heart of this paradigm is a meta-model that is an evolving, cohesive representation of the system and serves as the living single source of truth. MBSE provides benefits by enhancing productivity, enhancing quality, reducing risk, and providing improved communications among the system development team. The merging of design-to-cost philosophies within the frameworks of PMDA/PMDO and MBSE will create a powerful combination that produces robust and affordable liquid rocket engine designs to meet the demanding mission requirements of spaceflight.