Due to the limitations of mechanical actuation systems, methods involving control surface deflections to address gust loads suffer from low maneuvering efficiency and limited control effectiveness. Considering the poor static stability characteristics of flying-wing aircraft, a study was conducted on gust load alleviation using jet flow control, based on Computational Fluid Dynamics (CFD) simulations. Initially, the gust response characteristics of the flying wing aircraft were analyzed. Building upon this analysis, both wall jet and circulation control were employed to mitigate the aerodynamic loads induced by gusts. Additionally, a gust load alleviation control strategy based on pressure feedback was proposed. The results indicate that gusts predominantly alter the pressure distribution on the leading edge of the upper wing surface, thus affecting aerodynamic loads. Both wall jet and circulation control were found to be effective in controlling loads; however, the circulation control demonstrated higher efficiency in alleviating gust-induced loads under the current actuator parameters and configurations. In this study, a pressure feedback-based closed-loop control system was designed, which automatically adjusts the jet according to the intensity of the gusts to achieve load alleviation. Under closed-loop control based on pressure feedback, the root mean square value of the increment in lift coefficient induced by gusts was reduced by approximately 63.1%, and the root mean square value of the increment in pitch moment coefficient was reduced by approximately 72.1%.

The dragonfly is a flapping insect with excellent flying capabilities in nature, and its wings feature prominent corrugated structures. In this study, different types of corrugated airfoils, i.e. corrugation at the leading edge, corrugation at the trailing edge and corrugation along the whole chord are designed and compared with their smooth counterpart to investigate the effect of corrugation distribution on the aerodynamic characteristics of airfoils. Both gliding phase and flapping phase are simulated with the method of computational fluid dynamics (CFD). The chord Reynolds number (Re) based on the incoming velocity is varied from 1000 to 2000. The results show that, in the gliding phase, the recirculation zones formed within the corrugation produce negative frictional drag. The leading-edge corrugated airfoil has lower drag while the trailing-edge corrugated airfoil has higher lift and lift-to-drag ratio. The time-averaged lift coefficient and lift-to-drag ratio of the trailing-edge corrugated airfoil are increased by 23.1% and 9.1% respectively compared with the flat airfoil at $\alpha ={10}^{\circ }$. While at higher angles of attack, the aerodynamic characteristics of all airfoils are similar. Flow analysis shows that the trailing-edge corrugation increases the strength of leading-edge vortex (LEV) and the surface pressure difference upstream. In the flapping phase, the trailing-edge corrugation can decrease the negative lift generated in the upstroke, thereby increasing the cyclic-averaged lift. And the airfoil with corrugation along the whole chord has the highest cyclic-averaged lift because of stronger rotational circulation. This study suggests that it is an effective scheme to improve aerodynamic characteristics of airfoil by adjusting the corrugation distribution.

Vertical Takeoff and Landing (VTOL) aircraft combine the performance advantages of fixed-wing aircraft, such as long flight range and high speed, with the maneuverability and vertical takeoff and landing capabilities of rotorcraft. In recent years, VTOL aircraft have become a hot topic in the field of aircraft research. Tail-sitter VTOL aircraft, in particular, have garnered significant attention due to their simple structure and high weight efficiency. This article proposes a general layout scheme for a variable-wing tail-sitter VTOL aircraft, and designs a wing variant actuation mechanism with the self-locking function. Wind tunnel force measurements are conducted to study the aerodynamics of the aircraft in the fixed-wing cruise mode and quadcopter hover mode, and during the transition between these modes. The results offer valuable insights into the aircraft’s trimming capabilities and its flight performance in the fixed-wing cruise mode, as well as the aerodynamic characteristics during the forward transition phase. An elevon-rotor coordinated yaw enhancement control strategy is introduced to improve the yaw control effectiveness during the hover mode. By studying the aerodynamic forces acting on the aircraft during the transition process, a transition control strategy based on the airspeed and pitch attitude angle is developed. Flight tests are conducted to validate the aircraft’s performance, demonstrating good maneuverability and wind resistance of the aircraft in the quadcopter hover and fixed-wing cruise modes. The successful and smooth mode transitions without altitude loss validate the effectiveness of the control strategies.

Samara aircraft is a biology-inspired aircraft based on the samara. To improve the capability of the task execution of the samara aircraft, a combinable samara aircraft is designed. The combinatorial aircraft can be composed of two, three or six individual single samara aircraft through a combination box, and has the abilities of rapid assembly on the ground and controlled separation in the air. Based on the blade-element momentum theory, the aerodynamic model of single aircraft and combinatorial aircraft is established. It is found that the flight efficiency of combinatorial aircraft is 13. 3% higher than that of single aircraft. Then, the flight dynamics model and the outer loop control law for the aircraft are completed. Through six degrees of freedom flight simulation, the typical flight state of the aircraft and the process of controlled separation in the air are studied, which shows that the aircraft has the abilities of controlled flight and stable separation in the air. Finally, in the actual test flight, the controlled separation of the 3-combined aircraft is successfully realized. The design of the combinatorial aircraft and the technique of controlled separation make the aircraft obtain the dual advantages of high flight efficiency and UAV cluster.

As one of the promising configurations of the next generation of commercial aircraft, research on departure characteristics of the Blended-Wing-Body (BWB) is of great signification to safe flight limits. A three-degree-of-freedom (3-DOF) virtual flight test in a wind tunnel has been implemented for a candidate configuration to predict the departure characteristics. The support mechanism, the test model and the control law of the virtual flight test are introduced. In order to show the relationship between virtual flight test and actual flight test, the similarity criterion is also given. In open loop, the model has mild oscillations in the longitudinal and lateral directions, which are stable in closed-loop. The effect of flight control has been verified in virtual flight and actual subscale flight test. The analysis of system identification results indicate that the model has a good response to the excitation signal, and the response is in reasonable agreement with the flight test. Finally, the virtual flight departure test results are compared with the flight test. It shows that there is a good correspondence between the angle of attack and the elevator deflection at departure. This gives promising evidence of the practicability of virtual flight testing to predict departure of a BWB.