Foldable wings are designed for tube-launched unmanned aerial vehicles (UAVs), aiming to improve portability and meet launch platform requirements. However, conventional tube-launched UAVs cannot operate across the wide speed ranges required for the performance of multiple missions, due to the fixed configuration of their wings after launch. This study therefore proposes a tube-launched UAV which can change wing-sweep angle to expand the flight speed range and enhance the UAV’s agility. A computational aerodynamics method is employed to assess the transient aerodynamic performance of the UAV during the sweep morphing process. The simulation results indicate that the transient aerodynamic forces generate a dynamic hysteresis loop around the quasi-steady data. The lift and drag coefficients exhibit maximum relative deviations of 18.5% and 12.7% from the quasi-steady data for the sweep morphing period of 0.5 s. The hysteresis effect of the flow structure, rather than the additional velocity resulting from wing-sweep morphing, is the major contributor to the aerodynamic hysteresis loop. Compared to the conventional tube-launched UAVs, the proposed tube-launched UAV with a variable-sweep wing shows a wider flight speed range, from 22.59 to 90.12 m/s, and achieves an 82.84% increase in loitering speed. To verify the effectiveness of the wing-sweeping concept, a prototype was developed, and a flight test was carried out. The test data obtained from flight control system agree well with the simulation data, which demonstrates the feasibility and effectiveness of the variable-sweep wing in widening the speed range for tube-launched UAVs. This work can provide a reference for the design of tube-launched UAVs for wide speed range flight.

Ducted UAVs have attracted much attention because the duct structure can reduce the propeller tip vortices and thus increase the effective lift area of the lower propeller. This paper investigates the effects of parameters on the aerodynamic characteristics of ducted UAVs, such as co-axial twin propeller configuration and duct structure. The aerodynamic characteristics of the UAV were analyzed using CFD methods, while the impact sensitivity analysis of the simulation data was sorted using the orthogonal test method. The results indicate that, while maintaining overall strength, increasing the propeller spacing by about 0.055 times the duct chord length can increase the lift of the upper propeller by approximately 1.3% faster. Reducing the distance between the propeller and the top surface of the duct by about 0.5 times the duct chord length can increase the lift of the lower propeller by approximately 7.7%. Increasing the chord length of the duct cross-section by about 35.3% can simultaneously make the structure of the duct and the total lift of the drone faster by approximately 150.6% and 15.7%, respectively. This research provides valuable guidance and reference for the subsequent overall design of ducted UAVs.

The rising industrial demand for ultra-lightweight materials with exceptional strength and toughness has intensified interest in dual-phase Mg-Li alloys due to their low density and high specific strength. While much of the research on Mg-Li alloys has concentrated on conventional strengthening methods, such as grain refinement and solid-solution strengthening, overcoming the challenge of plastic deformation compatibility between the α- and β-phases remains unresolved. This study focuses on Mg-8Li binary alloy, systematically investigating the impact of rolling deformation temperature and strain on the phase structures. A detailed analysis of fracture behavior reveals a novel brittle–tough composite fracture control strategy that enhances both strength and toughness simultaneously. This work advances the understanding of phase structure control and its role in strengthening and toughening mechanisms, offering critical insights for the development of next-generation dual-phase magnesium alloys.

A tandem folding-wing UAV is investigated, focusing on simulation analysis of wing static and modal characteristics and deformation experiments. Using ANSYS Workbench, the structural stability and stiffness are evaluated numerically. The results demonstrate that the wingtip deformations are 48 mm for the front wing and 16 mm for the rear wing. The wingtip deformation discrepancy between the experiment and simulation result is within 8%, indicating the rationality of the prediction. The maximum equivalent stress remains below the material’s yield strength. Modal analysis is performed to identify the wing structure dynamic characteristics. The first six modal parameters are obtained for analyzing the natural frequency and vibration mode of the wing. The results in this study can provide a reference for the structural design of tandem wing UAVs.

This work investigates the aerodynamic characteristics and flight performance of a span-extendable aircraft under both retracted and extended wing configurations through numerical simulations. A validated computational fluid dynamics method is employed to capture the flow field distributions. The numerical results indicate that the extended-wing configuration significantly improves aerodynamic efficiency by reducing induced drag and increasing the effective angle of attack. A lift-to-drag ratio of 19.42 is achieved, representing a 34.58% improvement over the retracted configuration. The flight performance analysis reveals a 25% reduction in loitering speed, a 44% decrease in power consumption, a 34% increase in maximum flight range, and a 76% more flight endurance. These findings confirm the effectiveness of span-variable morphing wings in enhancing flight efficiency and provide valuable insights for the development of next-generation variable wing aircraft.