Reliability Allocation to Launch Vehicle Subsystems by Using AHP Method in Conceptual Design Phase

The goal of this paper is presenting a methodology for reliability allocation to launch vehicle subsystems using Analytical Hierarchy Process (AHP) method in conceptual design phase. In this methodology, the goal function is reliability and the main considered criterions are technology, complexity, operational time of each subsystem and cost. For applying AHP method to launch vehicle subsystems reliability allocation, a Matlab code(for investigating compatibility and determining allocation weight factors by employing Matrix Eigen Vector Method) and a Excel sheet(for forming the comparison matrix) are employed. To this point, by using the outcomes of liquid-propellant launch vehicle conceptual design software (LVCD) which developed by authors, the launch vehicle specifications and operational time of each subsystems is derived and is feed to this methodology as input. The results of applying this method to launch vehicle reliability allocation for the second stage of a launch vehicle, shows the error of this method below 2%. It is clear that this small error in reliability issues in conceptual design phase is acceptable.