Model Uncertainty: A Challenge in Nonlinear Coupled Multidisciplinary System Design

Abstract

This paper considers the e↵ects of uncertainty on multidisciplinary analysis estimates used in conceptual aircraft design. Specifically, the paper presents an analysis of the stability and control (S&C) characteristics of an illustrative Blended-Wing-Body (BWB) configuration using uncertain aerodynamic estimates. The S&C properties of a BWB are highly nonlinear, and as such pose a challenge for low-fidelity analysis techniques. By propagating bounds on uncertain aerodynamic data them through the analysis, bounds are derived for the resulting S&C limits. These estimates can then be used to guide future research and development e↵orts. Results demonstrate that even moderate uncertainty in estimating aerodynamic lift, drag, and moment coecients translates into large uncertainty in estimating the center of gravity limits, due to the highly nonlinear nature of the S&C model. The paper identifies directions for ongoing work using a multifidelity approach to address this issue.