Variation modes of avian wings offer large-scale morphing aircraft an effective approach for solving problems such as the mass center shift in longitudinal trim and control system design during the morphing process. In this paper, a numerical method is established for fully understanding the influence of combined morphing on roll efficiency of a biomimetic wing unmanned aerial vehicle (UAV) from the perspective of aerodynamic change, system convergence time and aerodynamic energy consumption. Analysis and simulation results show that the biomimetic wing provides effective measures to improve the mission execution efficiency of UAV. System oscillation can obviously be reduced with asymmetric sweep angle change as the supervisory control surface for pure roll maneuver, and actuators require higher output power than that with the single deflection of the flexible trailing edge (Flex-TE). In addition, for aircraft design, a larger mass ratio of the inner wing is beneficial to enhance system stability. Energy consumption of wing and Flex-TE show laws of first increasing and then decreasing along the spanwise direction during the morphing process. For actuators of the Flex-TE, the output power of units 1 to 15 should higher than other spanwise units. For the sweep angle generalized control surface, the maximum value of energy consumption per unit time is located near the 20-th spanwise unit. INDEX TERMS Multi-joint wing, control efficiency, control allocation, aerodynamic energy consumption.

In this study, a design scheme for a high-aspect-ratio bionic multi-section variable-sweep wing unmanned aerial vehicle (UAV) that utilizes the reverse coordinated change in the sweep angle of the inner and outer wing sections is proposed, which improves the aerodynamic performance and realizes the self-trim compensation of the wing’s centroid. According to the layout characteristics of this type of UAV, a reasonable distribution design of the wingspan ratio of the inner and outer sections is explored, to reduce the impact of aerodynamic center movement and moment of inertia change. The calculation and analysis results show that the coordinated variable-sweep scheme can significantly improve the influence of sweep angle change on the longitudinal static stability margin of UAVs with a high aspect ratio. The coordinated sweep angle change in the inner and outer wing sections can not only reduce the drag during high-speed flight, but also play a significant role in improving the performance of the aircraft at different stages in the mission profile. Appropriately increasing the wingspan proportion of the inner section can reduce the trim resistance of the V-tail, reduce the thrust of the engine, and increase the range and duration of the UAV. From the perspective of stability change, the multi-section variable-sweep wing UAV with a wingspan ratio of the inner and outer sections that is between 1.41 and 1.78 has better dynamic stability performance. Among them, the UAV with a wingspan ratio of the inner and outer sections that is equal to 1.41 has better longitudinal stability performance, while the UAV with a wingspan ratio of the inner and outer sections that is equal to 1.78 has better lateral/directional stability performance.