Comprehensive design method for aerodynamic performance and stability of HWB configuration in large cargo aircraft

To explore the application potential of the Hybrid Wing Body (HWB) configuration in the field of large cargo aircraft, an optimization design method balancing aerodynamic efficiency and dynamic stability is proposed. Taking the lift-to-drag ratio and the Dutch roll mode flight quality during the cruise phase as optimization objectives, an aerodynamic/stability optimization framework is constructed. An Euler equation solver with boundary layer corrections is employed for rapid analysis, while a high-fidelity RANS solver is used to validate the optimization results. Based on the analysis of the initial configuration, the optimization framework is applied to enhance the aerodynamic efficiency and dynamic stability modal response characteristics of the target configuration. RANS calculation results show that, under the premise of maintaining design constraints, the total drag coefficient of the aerodynamically optimized configuration is reduced by approximately 3.5 counts, with the cruise lift-to-drag ratio increasing from 21.244 to 21.784, achieving an efficiency improvement of approximately 2.54%. For the configuration optimized with both aerodynamic performance and dynamic stability objectives, the total drag coefficient is reduced by approximately 2.4 counts, the cruise lift-to-drag ratio is improved to 21.609 with an efficiency increase of approximately 1.72%, and the product of the Dutch roll mode damping ratio and the undamped natural frequency is increased from 0.02633 to 0.05117. This improvement elevates the flight quality from Level 3 to Level 2 according to the MIL-F-8785C standard, significantly enhancing the lateral-directional dynamic stability. The optimization framework effectively balances aerodynamic performance and dynamic stability, providing insights and references for the engineering application and optimization of HWB-configured large cargo aircraft.