Comparison Between Traditional Method (Statistical Method) and Multidisciplinary Optimization Method (AAO) in Designing of a Lightweight Liquid Propellant LV

One of the most important problems that nowadays are common in aerospace societies in Iran and also around the world is how to optimize the designing of the flight objects. Since the flight objects like LVs, which are the subject of this paper, are composed of several subsystems that have influences to each others, the multidisciplinary design optimization methods (MDO) are commonly used for doing design optimization of them. In usage of the multidisciplinary design optimization methods for different objects, to select the proper optimization algorithm is one of the very important problems. In this research the conceptual design of a lightweight liquid propellant LV is done with the all at once (AAO) method. The object of optimization is to minimize gross launch weight and four disciplines of structure, aerodynamics, trajectory, and propulsion are considered. Performance of gradient based algorithm of SQP and heuristic algorithm of GA and traditional method (statistical method) by solving an example are compared and is shown that if the output of statistical method is used as start point of optimization using gradient based algorithm of SQP, the global answer will be derived.