This paper proposes a new approach to constraint analysis for initial sizing. In a typical constraint analysis, the optimum combination of thrust loading and wing loading is chosen based on one's design experience. Such a selected design point may violate prescribed constraints because of the existence of uncertainties in parameters. To handle the uncertainties and to make a systematic aircraft design, this research performed the reliability-based design optimization (RBDO) applied to the constraint analysis, using the reliability index approach (RIA) and the performance measure approach (PMA). As an example, the constraint analysis of an air-to-air fighter was carried out with RBDO. The RBDO using RIA failed the search of the optimum point due to the divergence of reliability index at some initial points, whereas RBDO using PMA yielded stable and fast convergence results. Moreover, the results of deterministic optimization and RBDO with discrete target reliabilities are thoroughly discussed.
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