Abstract

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.

Highlights

  • Morphing aircraft can improve the aerodynamic performance, flexibility of mission execution, and comprehensive performance within the flight envelope, by changing the local or overall shape [1,2,3,4,5]

  • The aerodynamic and dynamic characteristics of a high-aspect-ratio wing aircraft change drastically during the morphing process. Changes in parameters such as the wingspan, wing area, and moment of inertia will cause the centroid and aerodynamic center to move in a large range, which may affect the stability, maneuverability, and flight performance, such as endurance, rate of climb, and fuel economy of the aircraft, adversely [6,7,8,9]

  • Sci. 2021, 11, 8859 configuration changes on the aerodynamic characteristics and stability of heavy-duty unmanned aerial vehicle (UAV) has not been fully clarified, and there is a lack of systematic research on the coordinate trim compensation mechanism of multi-section morphing wings with a high aspect ratio

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Summary

Introduction

Morphing aircraft can improve the aerodynamic performance, flexibility of mission execution, and comprehensive performance within the flight envelope, by changing the local or overall shape [1,2,3,4,5]. Sci. 2021, 11, 8859 configuration changes on the aerodynamic characteristics and stability of heavy-duty UAVs has not been fully clarified, and there is a lack of systematic research on the coordinate trim compensation mechanism of multi-section morphing wings with a high aspect ratio Under this morphing mode, the wingspan ratio of the inner and outer wing sections of the UAV will affect the design variables that determine the aircraft performance, such as the wingspan, aspect ratio, wing area, and sweep angle. In response to the above problems, a design scheme of a bionic multi-section variablesweep wing UAV that utilizes the reverse coordinated sweep angle change in the inner and outer wing sections is proposed, which improves the aerodynamic performance and realizes the centroid self-trim compensation.

Kane Dynamic Modeling Methods
Design of Stability Augmentation Systems
Overall Design of Bionic Multi-Section Variable-Sweep Wing UAV
Determination of Design Parameters of Targeted Morphing UAV
Influence Analysis of Static Stability
Aerodynamic Analysis of UAV Based on the Centroid Self-Trim Deformation
Multivariable Influence Analysis on Aerodynamic Characteristics of UAV
Multivariable Influence Analysis on Pitching Trim Characteritics of UAV
Stability Analysis and Augmentation Adjustment of UAV
Multi-Section Variable-Sweep Wing UAV System
Establishment and Linearization of Dynamic Equations
Influence Analysis of Dynamic Stability
Longitudinal Stability Augmentation Design
Discussions
Conclusions
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