Improving the Landing Control Capability of Blended Wing Body Configuration Solar-Powered UAVs by Using Swallow Tails and Distributed Propellers

This paper presents an innovative strategy to improve the landing capability of the solar-powered unmanned aerial vehicles (UAVs) with a low-speed and high-aspect-ratio blended wing body configuration by an innovative combination between the swallow tails and distributed differential propellers. It is proved that adjusting the opening angle of the swallow tails improves the UAV's stability, while higher yawing control efficiency of the differential throttle enhances the control efficiency at small throttle during the landing approach phase. The innovative yawing control method combining the opening of the swallow tails and a moderate separation of local airflow is validated via numerical flight simulations and landing flight tests. Thus, the damping ratio of the phugoid mode significantly increases, the lateral–directional control ability of the UAVs is enhanced in a simple but efficient way, the response speed is shortened, and the trajectory tracking accuracy is improved, even at higher altitudes and strong wind disturbances.