A Hybrid MDO Architecture for Launch Vehicle Conceptual Design

Abstract

The launch vehicle conceptual design must ideally refine propulsion systems and trajectory shaping together with vehicle sizing in an integrated manner to obtain the op- timum solution. This objective of optimizing the total launch vehicle system can be achieved by application of Multi-disciplinary Design Optimization (MDO) at conceptual design level. This study illustrates that launch vehicle conceptual design problem, for a given concept, can be formulated as an MDO problem. The development of an MDO strategy for solving this conceptual design problem is also presented here. A Two Stage Launch Vehicle (TSLV) design is considered for studies. In the process of identifying the suitable MDO architecture, studies with single-level formulations clearly establish the need for decomposition of the problem and bi-level architectures. A new bi-level architecture, referred to as Sequenced Collaborative Optimization with Nested Sequential Individual Discipline Feasible (SCO- NSIDF), is developed for implementation of the MDO problem of TSLV design. The successful implementation of SCO-NSIDF poses two challenges in terms of the disciplinary level optimizations, namely, automation of trajectory subsystem optimization and vehicle subsystem optimization. These challenges are overcome by a newly developed optimizing algorithm for the subsystem optimizations and applied to the TSLV design. This study demonstrates that launch vehicle conceptual design, for a given concept, can be formulated as an MDO problem and successfully solved using the proposed SCO-NSIDF architecture.