Stochastic Gust Analysis Techniques for Aircraft Conceptual Design

Dynamic loading constraints due to maneuver and gust loads are an important design consideration for novel aircraft configurations. Incorporating these constraints in the early design process with an appropriate level of fidelity presents a significant challenge, due both to the need for more detailed aerodynamics and control modeling, and to the stochastic nature of the gust encounter problem. This paper presents a stochastic gust analysis approach that is suitable for a multidisciplinary design optimization setting that incorporates dynamic loading constraints. The analysis approach employs Lyapunov and matched filter theory methods to address the stochastic nature of the gust response. A set of gust simulation studies are carried out to assess the relative importance of the various physics involved in aircraft gust encounters and the effects of different modeling assumptions. The study demonstrates the importance of modeling rigid body motion, pitch dynamics, and aircraft flexibility, but shows that for gust encounters at typical flight conditions, a quasisteady aerodynamics assumption is reasonable for load predictions over the majority of the wing acerage, meaning that full unsteady aerodynamic simulations are likely not required for typical gust lengths.