Abstract: The split drag rudders (SDRs) were usually used for the yaw control of tailless flying wing aircraft with the symmetric deflection mode. This approach was simple and effective, but the upper and lower deflectors of the SDRs were constrained to deflect symmetrically, limiting the distribution and control mode of the deflectors, reducing the maximum available moment in pitch axis and roll axis, affecting the handling performance of the aircraft flying at low speed. A certain flying wing UAV was used as the study model. The CFD method was adopt to investigate the aerodynamic characteristic of SDRs operating in either symmetrical or asymmetrical fashion. An allocation scheme based on convex coordinate rotation and optimization was proposed. The allocation efficiency of the method was studied. Simulation results show that the scheme has a high allocation efficiency, which can significantly improve the reachable moment subset of flying wing aircraft with the SDR asymmetrical deflection mode, enhance the controlling ability in pitch axis and yaw axis ,and improve the maneuverability of the aircraft.

Key words: tailless flying wing aircraft, split drag rudders, control allocation, reachable moment subset