Flying vertebrates exhibit sophisticated wingbeat kinematics. Their specialized forelimbs allow for the wing morphing motion to couple with the flapping motion during their level flight. Previous flyable bionic platforms have successfully applied bioinspired wing morphing but cannot yet be propelled by the morphing-coupled wingbeat pattern. Spurred by this, we develop a bioinspired flapping-wing aerial vehicle entitled RoboFalcon, which is equipped with a novel mechanism to drive the bat-style morphing wings, performs a morphing-coupled wingbeat pattern, and overall manages an appealing flight. The novel mechanism of RoboFalcon allows coupling the morphing and flapping during level flight and decoupling these when maneuvering is required, producing a bilateral asymmetric downstroke affording high rolling agility. The bat-style morphing wing is designed with a tilted mounting angle around the radius at the wrist joint to mimic the wrist supination and pronation effect of flying vertebrates’ forelimbs. Wind tunnel tests indicate that the rolling moment of the asymmetric downstroke is correlated with the flapping frequency, and the wrist mounting angle can be used for tuning the angle of attack, lift-thrust configuration, and power consumption of the equilibrium flight state. The agility of RoboFalcon is assessed through several tethered rolling maneuvers and outdoor free flight tests, and we present a concise analysis of the vehicle's lateral dynamics model based on system identification. We believe that this article yields a well-performing bionic platform and provides a new actuation strategy for the morphing-coupled flapping flight.

With the rapid development of high energy laser weapons (HELWs), the integration of HELW on unmanned combat aerial vehicles (UCAVs) has become a hot research topic. To study the impact of HELW on UCAV mission effectiveness, this paper proposes a 4-level design framework based on the system-of-system (SoS) oriented design. To validate the framework, the impact of HELW is analyzed in four aspects: the strike capability, the stealth performance, the vulnerability, and the defense capability, where the UCAV design constrains are noted. Simulation experiments of penetration scenario are carried out using agent-based modeling and simulation. The simulation results show that the integration of HELW can increase the survivability and mission effectiveness rate (MER) of the UCAV, especially for UCAVs with high speed and stealth performance. But the MER of the UCAV does not increase with the increase of HELW output power in most cases, indicating the importance of balancing the HELW and UCAV performances in concept design.

Wingtip slots, where the outer primary feathers of birds split and spread vertically, are regarded as an evolved favorable feature that could effectively improve their aerodynamic performance. They have inspired many to perform experiments and simulations as well as to relate their results to aircraft design. This paper aims to provide guidance for the research on the aerodynamic mechanism of wingtip slots. Following a review of previous wingtip slot research, four imperfections are put forward: vacancies in research content, inconsistencies in research conclusions, limitations of early research methods, and shortage of the aerodynamic mechanism analysis. On this basis, further explorations and expansion of the influence factors for steady state are needed; more attention should be poured into the application of flow field integration method to decompose drag, and evaluation of variation in induced drag seems a more rational choice. Geometric and kinematic parameters of wingtip slot structure in the unsteady state, as well as the flexibility of wingtips, should be taken into account. As for the aerodynamic mechanism of wingtip slots, the emphasis can be placed on the study of the formation, development, and evolution of wingtip vortices on slotted wings. Besides, some research strategies and feasibility analyses are proposed for each part of the research.

Bird-like flapping-wing aerial vehicles (BFAVs) have attracted significant attention due to their advantages in endurance, range, and load capacity. For a long time, biologists have been studying the enigma of bird flight to understand its mechanism. In contrast, aviation designers focus more on bionic flight systems. This paper presents a comprehensive review of the development of BFAV design. The study aims to provide insights into building a flyable model from the perspective of aviation designers, focusing on the methods in the process of overall design, flapping wing design and drive system design. The review examines the annual progress of flight-capable BFAVs, analyzing changes in prototype size and performance over the years. Additionally, the paper highlights various applications of these vehicles. Furthermore, it discusses the challenges encountered in BFAV design and proposes several possible directions for future research, including perfecting design methods, improving component performance, and promoting practical application. This review will provide essential guidelines and insights for designing BFAVs with higher performance.

The wing planform and flapping kinematics are critical for the hovering flight of flapping wing micro air vehicles (FWMAVs). The degree of influence of wing geometry and kinematic parameters on aerodynamic performance still lacks in-depth analysis. In this study, a sensitivity analysis was conducted based on the quasi-steady aerodynamic model. Each parameter was investigated independently by using the control variable method. The degree of each variable’s influence on lift, power, and power loading is evaluated and compared. Furthermore, detailed exponential relationships were established between the parameters and the corresponding aerodynamic properties. It is found that, for the geometric parameters, wing area has the greatest influence on lift, and the distribution of area has the most visible effect on aerodynamic power. All geometric parameters are negatively correlated with power loading. For the kinematic parameters, flapping frequency, compared with sweeping amplitude, results in faster lift growth and slower drop in power loading, while their influence on aerodynamic power is nearly comparable. A moderate pitching amplitude with advanced rotation will maximize the lift. For the flapping trajectory, lift and power loading are primarily affected by the shape of the pitching motion rather than the sweeping motion. But the sweeping motion seems to dominate the power consumption. The research in this paper is helpful to understand the effect of each parameter and provide theoretical guidance for the development of FWMAVs.

Flexible deformation of the insect wing has been proven to be beneficial to lift generation and power consumption. There is great potential for shared research between natural insects and bio-inspired Flapping wing Micro Aerial Vehicles (FWMAVs) for performance enhancement. However, the aerodynamic characteristics and deformation process of the flexible flapping wing, especially influenced by wing membrane material, are still lacking in-depth understanding. In this study, the flexible flapping wings with different membrane materials have been experimentally investigated. Power input and lift force were measured to evaluate the influence of membrane material. The rotation angles at different wing sections were extracted to analyze the deformation process. It was found that wings with higher elastic modulus membrane could generate more lift but at the cost of more power. A lower elastic modulus means the wing is more flexible and shows an advantage in power loading. Twisting deformation is more obvious for the wing with higher flexibility. Additionally, flexibility is also beneficial to attenuate the rotation angle fluctuation, which in turn enhances the aerodynamic efficiency. The research in this paper is helpful to further understand the aerodynamic characteristics of flexible flapping wing and to design bio-inspired FWMAVs with higher performance.