大展弦比长航时飞行器在飞行器发展中占有重要地位。对于亚声速飞行器来说，增大机翼的展弦比，是降低诱导阻力，提高巡航升阻比的最有效手段。但大展弦比飞行器也存在着对起降跑道要求高、抗风能力差的缺陷。变展长变体技术可以使飞机在起降和巡航两个飞行阶段拥有不同的翼展和气动外形，进而解决大展弦比飞行器的性能缺陷，但现有的变展长变体技术往往在结构增重、空间侵占等方面付出过高的代价，进而抵消了变体带来的性能收益。为此，本文发展和完善了一种单-双折叠翼变体飞行器的新概念。这种变体飞行器使用气动力驱动变体，在获得50%变展长能力的同时，极大降低了变体所需要付出的各方面代价，在多个方面优于现有的变展长变体飞行器。在这一新概念的基础上，本文进一步开展了单-双折叠翼变体的气动特性研究、动力学和控制研究、结构机构设计研究。在气动特性研究中，重点分析了单-双折叠翼变体飞行器在双翼构型下的气动特性、变体过程中的气动特性以及气动力驱动变体的副翼特性，总结形成了单-双折叠翼变体飞行器的气动设计规律和设计准则；在动力学和控制研究中，建立了单-双折叠翼变体的动力学模型，明确了单-双折叠翼变体的控制方案，并进一步讨论了变体对于飞机稳定性的影响；在变体的结构机构设计研究中，分析了变体过程中机翼和机构的传力路径和受力特性，并进一步以“全球鹰”无人机为原准机，开展了变体机构的强度刚度设计，形成了单-双折叠翼变体飞行器结构设计方案。此后，基于以上三项研究内容，本文进一步开展了单-双折叠翼变体飞行器总体设计方法研究，分析了单-双折叠翼变体飞行器总体设计中气动、结构、控制等多个学科之间的耦合作用，明确了其设计约束和设计准则，发展了适用于单-双折叠翼变体飞行器的飞机总体参数拟定方法和平面形状设计方法，并进一步分析单-双折叠翼变体的收益和代价。最后，本文还开展了单-双折叠翼变体的原理验证研究，研制了单-双折叠翼变体原理验证机并开展了空中变体飞行试验和地面车载变体试验。通过这些试验，充分验证了单-双折叠翼变体概念的合理性和可行性，综合检验了本文中所形成的单-双折叠翼变体飞行器设计方法。
High aspect ratio long-endurance aircraft plays an important role in the development of aircraft. For subsonic aircraft, increasing the aspect ratio is the most effective way to reduce the induced drag and improve the cruise lift-drag ratio. However, aircraft with a high aspect ratio also has the defects of high requirements for takeoff /landing runways and poor wind resistance. The variable-span morphing technology can make the aircraft have different wingspan and aerodynamic shapes in the two flight phases of takeoff/landing and cruise, thus solving the performance defects of the high-aspect-ratio aircraft. However, the existing variable-span morphing technology often pays a high price in terms of structural weight gain, space occupation, and so on, thus offsetting the performance benefits brought by the morphing. To this end, this paper developed and perfected a new concept of monoplane-biplane morphing aircraft. This morphing aircraft uses aerodynamics to drive morphing, which greatly reduces the cost of the morphing and is superior to the existing morphing aircraft in many aspects while obtaining the variable-wingspan capability of 50%. Based on this new concept, this paper further carried out the research on aerodynamic characteristics, dynamics and control, and structural mechanism design of the monoplane-biplane morphing aircraft. In the study of aerodynamic characteristics, the aerodynamic characteristics in the biplane configuration, the aerodynamic characteristics during the morphing process, and the aileron characteristics of the aerodynamic-driven morphing were emphatically analyzed, and the aerodynamic design regular pattern and criteria are summarized; In the research of dynamics and control, the dynamics model of the monoplane-biplane morphing is established, the control scheme was defined, and the influence of the morphing on the aircraft stability was further discussed; In the structural mechanism design research of the morphing, the force transmission path and force characteristics of the wing and morphing mechanism during the morphing process were analyzed, and the strength and stiffness design of the variant mechanism was further carried out with the "Global Hawk" UAV as the original aircraft, forming the structural design scheme of the monoplane-biplane morphing aircraft. Since then, based on the above three research contents, this paper further carried out the research on the overall design method of the monoplane-biplane morphing aircraft, analyzed the coupling between the aerodynamics, structure, control, and other disciplines in the overall design of the monoplane-biplane morphing aircraft, clarified its design constraints and design criteria, and developed the aircraft overall parameter formulation method and plane shape design method applicable to the monoplane-biplane morphing aircraft. The benefits and costs of the monoplane-biplane morphing were further analyzed.Finally, this paper also carried out the principal verification research of the monoplane-biplane morphing, developed the monoplane-biplane morphing principle verification UAV, and carried out the flight morphing test and the ground vehicle morphing test. Through these tests, the rationality and feasibility of the concept of the monoplane-biplane morphing aircraft were fully verified, and the design method of monoplane-biplane morphing aircraft formed in this paper was also comprehensively verified.
