Multifidelity Optimization of Hybrid Wing-Body Aircraft with Stability and Control Requirements

Methods of satisfying the stability and control (S&C) requirements for hybrid wing-body (HWB) aircraft are investigated using a multifidelity multidisciplinary optimization framework. A Reynolds-averaged Navier-Stokes solver is used for aerodynamic prediction, together with conceptual-level weight and balance models. These are coupled with a gradient-based optimizer to form a multidisciplinary optimization tool. Two HWB configurations are investigated. The first uses winglets with winglet-mounted rudders for lateral control, whereas the second uses centerbody-mounted fins with rudders. Longitudinal control is achieved with one centerbody elevator and six wing-mounted elevons. The designs are optimized for a combination of minimum/maximum takeoff weight and cruise drag. The ability of the designs to maintain lateral trim with one engine inoperative at a specified minimum control speed and to achieve a given rotational acceleration at a specified rotation speed forms the off-design S&C constraints. Additional constraints at cruise ensure trim and a required static margin. In addition to a classical HWB shape, a narrower cabin layout is also considered, which provides an improved performance. The required S&C requirements are found to be attainable using both configurations, with the fin-based control having a small performance advantage. The narrow-centerbody configuration is found to provide superior performance over the classical configuration.