动力增升对翼身融合飞机沉降特性的改善

翼身融合体飞机起降阶段的“沉降问题”是影响该类布局飞行安全的典型问题，为此提出了一种将动力风扇竖直嵌入机翼中的动力增升方案。分析了动力增升系统对飞行的气动影响，提出了动力增升系统的匹配设计和评价方法，探讨了动力增升系统布局的主要约束。在综合考虑动力增升系统推质比、俯仰力矩配平以及操稳特性等限制因素基础上，基于示例翼身融合体无人机，匹配设计了动力增升系统及其布局方案，针对过渡飞行状态设计了姿态稳定控制律。飞行试验表明:使用动力增升能缓解进近阶段升降舵操纵所引起的下沉率突增与高度沉降现象，同时可将验证机的起、降速度降低20%以上，且该方案易于在小型翼身融合体飞机上实现。 

Improvement of powered lifting scheme on the saggingcharacteristic of blended wing body aircraft

Blended wing body aircraft frequently shows the sagging phenomenon, which is a safety sensitive problem in takeoff and landing. Focusing on the problem, a powered lifting scheme by use of ducted fan in wings was presented. Aerodynamic effect of the powered lifting system on flight was analyzed. A matched design and assessment method for the powered lifting system was established, and the main constraints of the layout were integrated. Taking the thrust weight ratio of the system, pitching trim, maneuverability and stability into consideration, a blended wing body drone was used as example and the powered lifting system and its layout scheme were presented. For smooth transition of flight phases, an attitude stabilization control law was further introduced. Flight tests show that the powered lifting device can mitigate the sudden increase of sink rate and height sagging phenomenon due to elevator deflection in approaching stage. Meanwhile, the scheme can reduce the takeoff and landing velocity by over 20%, and the scheme is apt to be implemented on small size of blended wing body aircraft.