The basic concepts, modeling analysis, and optimization solutions of MDO have been described in the previous chapters. However, MDO is essentially an application technique, and the effect of its application on a flight vehicle is the most important criterion to test the theory. Therefore, some MDO application cases will be presented from this chapter onward. It is worth mentioning that the MDO method is a general application technique that can be used for both vehicle subsystems (e.g., structure, thermal layout, wings, and engines, etc.), overall vehicle (e.g., missiles, aircraft, satellites, etc.), and vehicle systems (e.g., spacecraft in-orbit service systems, etc.).