Decomposition of Mathematical Programming Models for Aircraft Wing Design Facilitating the Use of Dynamic Programming Approach

Aircraft designers strive to achieve optimal weight-reliability tradeoffs while designing an aircraft. Since aircraft wing skins account for more than fifty percent of their structural weight, aircraft wings must be designed with utmost care and attention in terms of material types and thickness configurations. In particular, the selection of thickness at each location of the aircraft wing skin is the most consequential task for aircraft designers. To accomplish this, we present discrete mathematical programming models to obtain optimal thicknesses either to minimize weight or to maximize reliability. We present theoretical results for the decomposition of these discrete mathematical programming models to reduce computer memory requirements and facilitate the use of dynamic programming for design purposes. In particular, a decomposed version of the weight minimization problem is solved for an aircraft wing with thirty locations (or panels) and fourteen thickness choices for each location to yield an optimal minimum weight design.

Structural Design and Analysis of Small Flapping Wing Aircraft Based on the Crank Slider Mechanism

In this project,the miniaturization of the aircraft was realized under the premise of strong maneuverability,high concealability,and driving a certain load,and the flight mode and structural characteristics of birds were imitated.A small bionic flapping wing aircraft was built.The flapping of the wing was realized by the crank slider mechanism,and the sizes of each part were calculated according to the bionics formula.The wingspan was 360.37 mm,the body width was 22 mm,the body length was 300 mm,the wing area was 0.05 m^(2),the flapping amplitude was 71°.ADAMS software was used to simulate the dynamics of the designed aircraft,and the variation of flapping amplitude and angular velocity during the movement of the aircraft was obtained,which verified the feasibility of the mechanism.The prototype aircraft was made for flight test,and the designed bionic flapping wing aircraft achieved the expected effect.It provides a theoretical basis and data support for the design and manufacture of small flapping wing aircraft.

Adaptive Kalman Filter of Transfer Alignment with Un-modeled Wing Flexure of Aircraft

The alignment accuracy of the strap-down inertial navigation system （SINS） of airborne weapon is greatly degraded by the dynamic wing flexure of the aircraft. An adaptive Kalman filter uses innovation sequences based on the maximum likelihood estimated criterion to adapt the system noise covariance matrix and the measurement noise covariance matrix on line, which is used to estimate the misalignment if the model of wing flexure of the aircraft is unknown. From a number of simulations, it is shown that the accuracy of the adaptive Kalman filter is better than the conventional Kalman filter, and the erroneous misalignment models of the wing flexure of aircraft will cause bad estimation results of Kalman filter using attitude match method.

OPTIMAL DESIGN AND AERODYNAMIC CALCULATION OF WING CONFIGURATION OF CIVIL AIRCRAFT

An effective method of optimal design of wing configuration is provided. The SUMT (sequential unconstained minimization technique) method is a good technique for solving the nonlinear programming. The application of penalty in optimal design of wing configuration has been solved well. The present method for the aerodynamic calculation is the combination of both the nonlinear panel method and the suction analogy method of vortexlift spanwise distribution on large swept wing-tip. The calculation results are in good agreement with experimental data. According to the computation and experiment,the mechanism of the increased lift and reduced drag about the sheared wing-tip wing has been analyzed, and some opinions of interest are proposed.

EXPERIMENTAL RESEARCH OF THE CONFIGURATION OF WING－TIP DRAG REDUCTION FOR LIGHT AIRCRAFT

hree kinds of devices of drag reduction are presented swept wingtip,stage by stage swept wingtip and downbend wingtip. The effects of changing geometryparameters of the swept wingtip on the drag reducing are also presented. Wind-tunnelexperiment results indicate that a properly designed swept wingtip results in an incre-ment in induced efficiency of 4%～ 7% and that swept wingtip can increase longitudinalstatic-stability. Water-tunnel experiment results indicate that the reason for drag re-ducing of swept wingtip is that when the angle of attack is not zero, the strong end vor-tex of the wing is weakened by the combined effect of the leading edge and trailing edgevortices of the swept wingtip.

Parametric CAD Modelling of Aircraft Wings for FEA Vibration Analysis

Excessive vibration of aircraft wings during flight is harmful and may cause propagation of existing cracks in the material, leading to catastrophic failures as a result of material fatigue. This study investigates the variations of modal characteristics of aircraft wings with respect to changes in the structural configurations. We develop parametric Computer-Aided Design (CAD) models to capture new design intend on the aircraft wing architectures. Subsequent Finite Element Analysis (FEA) based vibration analysis is performed to study the effects of architecture changes on the wing’s natural frequencies and mode shapes. It is concluded that the spar placement and the number of ribs have significant influence on the wing’s natural vibration properties. Integrating CAD modelling and FEA vibration analysis enables designers to develop alternative wing architectures to implement design requirements in the preliminary design stage.

Conceptual Design and Aerodynamic Study of Joined-Wing Business Jet Aircraft

The concept of joined-wing aircraft with nonplanar wings as conceived and patented by Wolkovitch is attractive due to various advantages such as light weight, high stiffness, low induced drag, high trimmed CLmax, reduced wetted area and parasite drag and good stability and control, which have been supported by independent analyses, design studies and wind tunnel tests. With such foreseen advantages, the present work is carried out to design joined-wing business-jet aircraft and study and investigate its advantages and benefits as compared to the current available conventional business jet of similar size, passenger and payload capacity. In particular, the work searches for a conceptual design of joined-wing configured business-jet aircraft that possesses more superior characteristics and better aerodynamic performance in terms of increased lift and reduced drag, and lighter than the conventional business jet of similar size. Another significant objective of this work is to prove that the added rigidity possessed by the joined wing configuration can contribute to weight reduction.

A Dynamic Programming Approach to the Design of Composite Aircraft Wings

A light and reliable aircraft has been the major goal of aircraft designers. It is imperative to design the aircraft wing skins as efficiently as possible since the wing skins comprise more than fifty percent of the structural weight of the aircraft wing. The aircraft wing skin consists of many different types of material and thickness configurations at various locations. Selecting a thickness for each location is perhaps the most significant design task. In this paper, we formulate discrete mathematical programming models to determine the optimal thicknesses for three different criteria: maximize reliability, minimize weight, and achieve a trade-off between maximizing reliability and minimizing weight. These three model formulations are generalized discrete resource-allocation problems, which lend themselves well to the dynamic programming approach. Consequently, we use the dynamic programming method to solve these model formulations. To illustrate our approach, an example is solved in which dynamic programming yields a minimum weight design as well as a trade-off curve for weight versus reliability for an aircraft wing with thirty locations (or panels) and fourteen thickness choices for each location.

Retarded Harrier Maneuver as a New and Efficient Approach for Fixed-Wing Aircraft to Achieve S/VTOL

Modern day VTOL fixed-wing aircraft based on quadplane design is relatively simple and reliable due to lack of complex mechanical components compared to tilt-wings or tilt-rotors in the pre-80’s era. Radio-controlled aerobatic airplanes have thrust-to-weight ratio of greater than unity and are capable of performing a range of impressive maneuvers including the so-called harrier maneuver. We hereby present a new maneuver known as the retarded harrier that is applicable to un/manned fixed-wing aircraft for achieving VTOL flight with a better forward flight performance than a quadplane in terms of weight, speed and esthetics. An airplane with tandem roto-stabilizers is also presented as an efficient airframe to achieve VTOL via retarded harrier maneuver, and detailed analysis is given for hovering at 45° and 60° and comparison is made against the widely adopted quadplane. This work also includes experimental demonstration of retarded harrier maneuver using a small remotely pilot airplane of wingspan 650 mm.

柔翼结构飞行器智能控制系统关键技术与途径

柔翼结构飞行器具有轻质、空间集成、重复使用、有较大的阻力面积和升力系数等优点,可实现巡航飞行、低速驻空、再入返回、气动减速、定点归航、着陆缓冲等功能,是当前的研究热点。智能控制系统是柔翼结构飞行器飞航与回收着陆系统的核心技术之一,结合智能技术在控制系统中的应用研究与工程实践,对柔翼结构飞行器智能控制系统及其技术特征进行了分析;介绍了刚-柔组合体一体化控制与仿真、环境感知与健康状态在线评估、航迹规划与跟踪飞行控制、集群飞行控制、着陆与缓冲智能控制、智能硬件容错与重构等关键技术。对柔翼结构飞行器智能控制系统的未来发展进行了思考,提出了飞行环境的智能及柔性感知、气动参数的在线识别、多任务模式自主执行及控制系统的演进学习等发展建议,通过对智能控制技术持续不断地研究与实践,为柔翼结构飞行器系统的研制提供强有力的支撑。

飞翼布局飞行器研究现状分析

对飞翼布局飞行器的发展脉络进行了梳理,涵盖了从其早期的进化史到现阶段的研究进展,并对未来的发展方向进行了思考和展望。同时,论述了飞翼布局飞行器的几个主要控制难点,具体包括:宽速域非线性状态下的姿态控制问题、多效应耦合下的高精度自主起降控制问题、气动模型近似及强扰动状态下的鲁棒控制难题,以及因多舵面冗余而引起的控制分配问题。此外,还深入讨论了当前重点研究的飞翼布局飞行器的流动控制问题,并对接下来主动流动控制技术的研究动向进行了阐述。

倾转机翼/旋翼机过渡姿态规划分析

针对带有倾转机翼段的新构型倾转旋翼机复杂的倾转过渡变构型过程,提出一种基于动量叶素理论的高速段倾转走廊边界计算方法。通过低速时机翼失速限制和高速时旋翼可用功率限制建立倾转过渡走廊计算模型,对比了传统构型倾转旋翼机和倾转机翼/旋翼机的倾转过渡走廊差别。对2种构型倾转旋翼机倾转过渡状态下前飞速度、机身迎角、旋翼桨距角姿态进行了对比分析。结果表明:带有倾转机翼段的倾转机翼/旋翼机具有更狭窄的倾转走廊,在短舱角0°状态,倾转机翼段占1/3展长的旋翼机相较于传统构型倾转旋翼机,倾转速度边界从39~57 m/s缩减到41.7~51.2 m/s,倾转操纵难度加大;在大于45°短舱角的倾转前期,同样的前飞速度和短舱倾转角状态下,倾转机翼/旋翼机机身迎角降低约2°,旋翼桨距角增大1°~4°,随着倾转过渡的完成,2种构型倾转旋翼机姿态差异逐渐变小。

高超声速变体飞行器关键技术研究综述

高超声速变体飞行器有潜力通过变形提升飞行器在宽速域、大空域飞行全包线下的适用性,在未来的民用与军事领域都具有极大的战略意义。本文主要对高超声速变体飞行器的研究进展进行综述,阐述了国内外高超声速和变体飞行器项目的研究进展和现状,并且对现有的高超声速变体飞行器的主要变形方式进行了分类与介绍。同时,总结了高超声速变体飞行器在变构型机构设计方法与理论、高功重比与快速响应的驱动设计、可承载大变形蒙皮、承载/热防护一体化结构设计等方面的技术难点,提出了高超声速变体飞行器的后续研究发展方向,以期对后续高超声速变体飞行器的相关研究提供一定的参考。

倾转旋翼飞行器机翼滑流区面积可视化计算方法

机翼滑流区面积计算是进行倾转旋翼飞行器旋翼与机翼气动干扰分析的关键,针对倾转旋翼飞行器机翼滑流区面积计算,基于CATIA二次开发和参数化设计技术,结合气动计算和三维几何图形运算,提出一种可视化计算方法,其能够在考虑机翼和旋翼参数影响的情况下,准确计算机翼滑流区面积,并且能够直观地确定机翼滑流区区域及机翼滑流区随各项参数的动态变化过程。通过基于XV-15倾转旋翼飞行器参数进行实例计算和分析,结果表明:机翼安装角、后掠角、上反角等机翼参数在纵向和侧向分析时对机翼滑流区面积影响较小;旋翼后倒角、侧倒角及旋翼主轴侧倾角等旋翼参数对机翼滑流区面积影响较大;在不考虑旋翼后倒角和侧倒角的情况下,采用所提方法对XV-15倾转旋翼飞行器机翼滑流区面积进行计算,计算精度最大可提升18.976%。

飞行器折叠翼展开冲击环境条件研究

带折叠翼飞行器在结构上与传统飞行器略有差异,其翼展开冲击环境条件的制定无相似型号及经验可参考。本文针对飞行器折叠翼展开冲击环境条件问题,通过分析五种条件制定方法,对不同样本量情况下飞行器折叠翼展开冲击环境进行研究,给出了该类型飞行器折叠翼展开冲击环境条件的制定方法。

折叠翼飞行器气动弹性变体飞行仿真平台

折叠翼飞行器的变体过程伴随质量分布、刚度分布及气动载荷分布的大幅动态变化,是一个高度复杂的动力学过程。为实现该过程各种动力学问题的有效分析,基于共享内存技术开发了一套高性能的耦合计算程序,并在此基础上整合了Adams多体动力学计算软件、非定常气动力计算程序及飞行控制技术,搭建了折叠翼的气动弹性变体飞行仿真平台。基于该平台,对折叠翼进行了气动弹性分析和飞行变体过程仿真,验证了平台强大的计算和分析能力。

固定翼飞机转运体外膜氧合患者经验总结

目的总结体外膜氧合(ECMO)危重症患者固定翼飞机转运经验。方法回顾性收集并分析我国2017年5月至2023年3月北京市红十字会999专业航空医疗救援联合相关医疗单位采用固定翼飞机转运的11名ECMO支持患者信息,总结ECMO患者固定翼飞机转运中的注意事项以及可能发生的不良事件。结果男性9名,女性2名,平均年龄(56.6±16.6)岁;10例患者诊断重症肺炎,1例患者诊断心肌病合并心源性休克;静脉-静脉ECMO 10例,静脉-动脉ECMO 1例;2例(18%)患者采用B-1999固定翼飞机转运,9例(82%)采用B-5999固定翼飞机转运,飞行距离(713.9±388.6)km,飞行时间(1.5±0.7)h,转运总时间(4.4±0.8)h;转运医护团队包括4人(医生2名,护士2名)。所有患者均成功转运,其中两名患者在转运途中出现不良反应(心率下降、飞行中氧分压降低)。结论在专业、经验丰富的ECMO医护团队和设备准备充分的情况下,固定翼飞机空中医疗救援ECMO患者安全可行。

有翼飞行器初制导阶段两段式协同集结方法

针对多枚有翼飞行器初制导阶段跨大空域飞行的协同集结问题,将协同集结问题转化为初始部署点到编队协同飞行区域之间的时间与位置协同问题。将协同集结过程划分为两个阶段,第一阶段飞行器间无信息交互,设计了带有集结角度约束的第一阶段时间协同集结方法,为各枚飞行器指定共同的集结时间和集结角度,采用模糊逻辑实现航迹控制与速度控制的合理分配,在可靠建立通信拓扑且满足终端放宽判断条件后,转入第二阶段协同集结飞行。第二阶段飞行器利用相互间构建的通信拓扑交互信息,为跟随者飞行器设计了基于编队跟踪控制的协同集结方法,通过李雅普诺夫理论对闭环系统稳定性进行了证明。仿真算例验证了所提方法的有效性。

仿生扑翼飞行器姿态稳定控制设计与实验

针对扑翼飞行器在飞行过程中姿态调整控制问题,提出了一种快速响应的自动姿态稳定控制方法。利用牛顿定律和动量矩定理建立扑翼飞行器数学模型,结合扑翼飞行器姿态变化工作原理,研究飞行过程中姿态调整控制方案策略。采用串级PID控制算法设计姿态调整内环和外环控制器,以扑翼飞行器欧拉角为输出,对扑翼飞行器姿态调整过程进行了仿真计算以及外场飞行实验。通过对扑翼飞行器姿态角的响应仿真分析及外场飞行实验数据分析,验证了扑翼飞行器数学模型的准确性及姿态控制器的有效性。结果表明:在阶跃信号输入下,姿态角能快速响应并快速趋于稳态,外场飞行中扑翼飞行器俯仰角保持15°,飞行加速度保持1 m/s^(2),可以较好地自动保持姿态稳定。

涡轴-涡扇变循环发动机方案及性能匹配设计研究

针对旋转机翼式垂直起降高速巡航飞行器,提出了一种新概念结构形式的涡轴-涡扇变循环(TSFVCE)发动机,能够分别在涡轴和涡扇两种模态工作。首先对涡轴-涡扇变循环发动机的结构及工作模式进行了介绍,并建立基于变比热的部件级性能仿真模型;然后通过循环分析,确定发动机第二涵道比为3,Flade外涵风扇压比为1.98,第一涵道比为0.11,完成发动机设计点性能方案设计;最后分析了核心机驱动风扇(CDFS)可调机构对发动机性能影响机理,得出CDFS放气阀对发动机涡扇模态下的推力与涡轴模态下的功率影响较大,对涡扇模态的推力影响最大为61.5%,对涡轴模态的功率影响最大为33.3%,可利用此特性实现发动机在涡扇和涡轴模态下推力和功率输出的匹配。