Electromechanical Actuation Technology for the All-Electric Aircraft

Electromechanical actuation is a critical element that must be developed and verified to make the all-electric aircraft a viable concept. For several years the Flight Control Division of the Air Force Wright Aeronautical Laboratories has sponsored activities to demonstrate the credibility of electromechanical actuation systems (EMAS) for primary flight control actuation functions. The foundation for these EMAS activities and several electromechanical actuation development programs are described here. One involves the design, fabrication, and laboratory test of a rotary, hingeline electromechanical actuator. Another involves the development and flight test demonstration of a linear electromechanical actuator for controlling an aileron of a C-141 aircraft. A third involves the design and development of a linear electromechanical actuator for missiles having severe performance, temperature, and volumetric requirements. In addition, a brief summary of the results from two aircraft actuation trade studies compare the baseline (conventional) hydraulic flight control system with an all-electric airplane concept including quantitative comparisons of weight, reliability and maintainability, and life cycle costs.     

特种飞机配电系统设计分析

随着国内大飞机平台和航空电子技术的快速发展,未来我国军用特种飞机设计过程必将体现多电化/全电化设计理念。配电系统作为飞机的关键分系统,对多电/全电飞机而言,重要性更加突出。主要论述特种飞机配电系统设计,分析了当前国内外飞机配电技术的发展现状和特种飞机典型配电系统架构设计方案,针对我国军用特种飞机电源系统发展趋势,提出了未来特种飞机配电系统设计思路,为新一代特种飞机配电系统设计提供了重要参考。     

一种电动飞机概念方案的参数设计方法

为了准确地进行电动飞机概念方案的设计评估,从其自身特征出发,结合任务需求和不同飞行阶段的能耗分析,建立了全机总质量评估模块;为了完成方程的封闭和满足必要的飞行性能约束,建立了参数矩阵图模块;搭建的设计系统可以有效评估起飞总质量、翼载荷、功率载荷和翼展等总体参数。基于该系统,对国内外三款电动飞机进行设计和对比分析:不同机型下,程序所得的各项质量、翼面积、展长和翼载荷等均与实际数据相近;各项数据对比的绝对数值差异反映出对于任务的模拟和能耗在合理范围之内,且其相对误差对于初级设计阶段的总体参数评估而言,也是可以接受的。这些研究结果不仅验证了本文设计方法的正确性和可行性,还表明了该方法可为电动飞机初步的参数选定和性能评估提供重要的设计支撑。      

Flight Safety Issues of an All-Electric Aircraft

Flight safety issues of an all-electric aircraft include flight control system reliability, protection from electromagnetic interference and lightning, and protection from design errors (primarily in software) and handling qualities when failures occur if the all-electric aircraft does not have traditional aerodynamic stability. Some of these questions already have partial answers, but others remain open. The Federal Aviation Administration expects that discussions with experts in the aviation industry, the military services, the National Aeronautics and Space Administration, and foreign regulatory authorities for civil aircraft will be necessary to resolve these issues.     

Motor drive technologies for the power-by-wire (PBW) program:options, trends and tradeoffs. I. Motors and controllers

The Power-By-Wire (PEW) program involves the replacement of hydraulic and pneumatic systems currently used in aircraft with an all-electric secondary power system. One of the largest loads of the all-electric secondary power system will be the motor loads which include pumps, compressors and Electrical Actuators (EAs). Issues of improved reliability, reduced maintenance and efficiency, among other advantages, are the motivation for replacing the existing aircraft actuators with electrical actuators. The EA system contains the motor, the power electronic converters, the actuator and the control system, including the sensors. This paper and a companion paper give a comparative literature review in motor drive technologies, with a focus on the trends and tradeoffs involved in the selection of a particular motor drive technology. The reported research comprises the induction motor (IM), the brushless dc motor (BLDCM) and the switched reluctance motor (SRM) drive technologies. Each of the three drives has the potential for application in the PEW program. Many issues remain to be investigated and compared between the three motor drives, using actual mechanical loads expected in the PBW program     

Advanced Aircraft Electric System

The topics, advanced aircraft electric system and all-electric airplane, inspire a broad range of concepts from the evolutionary to the revolutionary. The revolutionary developments are exciting to the research and development community but find little encouragement or acceptance from airframe developers whose objective is to build an advanced technology airplane using only-off-the-shelf, proven equipment. Their anthem rings "We know how bad the ___________ is, but we have learned to live with it. We have only your vision of how good an advanced system will be and fear to chance it. "However, the cost of living with these known systems combined with the escalating cost of fuel and the military need to address advanced mission capability demands more than a patch called improved reliability and maintainability. The time is at hand to demonstrate an evolutionary approach to achieve a revolutionary improvement. This paper describes an advanced electric system, the life cycle cost improvement anticipated, and the evolutionary means to implementation.     

Moving towards a more electric aircraft

The latest advances in electric and electronic aircraft technologies from the point of view of an "all-electric" aircraft are presented herein. Specifically, we describe the concept of a "more electric aircraft" (MEA), which involves removing the need for on-engine hydraulic power generation and bleed air off-takes, and the increasing use of power electronics in the starter/generation system of the main engine. Removal of the engine hydraulic pumps requires fully-operative electrical power actuators and mastery of the flight control architecture. The paper presents a general overview of the electrical power generation system and electric drives for the MEA, with special regard to the flight controls. Some discussion regarding the interconnection of nodes and safety of buses and protocols in distributed systems is also presented     

DIMA架构下飞机全电刹车系统故障传播行为分析与评估

在DIMA平台开放性体系架构的背景下,飞机航电与机电等系统功能逐渐渗透融合,面向DIMA架构的全电刹车系统是未来飞机刹车系统的主流设计趋势,但目前尚未形成针对DIMA架构下全电刹车系统的故障传播行为分析与评估方法。针对上述问题,首先结合DIMA架构特征和全电刹车相关标准,分析面向DIMA架构下的全电刹车系统分层架构,在此基础上构建全电刹车系统任务-功能-资源层次模型。其次,考虑到DIMA平台资源共享的特点,结合系统层次模型开展系统耦合关联分析,引入Floyd算法计算间接耦合矩阵以及路由矩阵,通过构造失效严重程度矩阵量化系统关联耦合度,建立系统故障传播结构模型,综合考虑故障路径传播概率和系统边缘介数,构建DIMA架构下全电刹车系统故障传播强度模型,以识别系统故障传播关键路径,完成故障传播行为分析与评估。最后通过实例分析,以验证所提方法的正确性与合理性。     

Radiation Belt Storm Probes (RBSP) Education and Public Outreach Program

The Radiation Belt Storm Probes (RBSP) Education and Public Outreach (E/PO) program serves as a pipeline of activities to inspire and educate a broad audience about Heliophysics and the Sun-Earth system, specifically the Van Allen Radiation Belts. The program is comprised of a variety of formal, informal and public outreach activities that all align with the NASA Education Portfolio Strategic Framework outcomes. These include lesson plans and curriculum for use in the classroom, teacher workshops, internship opportunities, activities that target underserved populations, collaboration with science centers and NASA visitors’ centers and partnerships with experts in the Heliophysics and education disciplines. This paper will detail the activities that make up the RBSP E/PO program, their intended audiences, and an explanation as to how they align with the NASA education outcomes. Additionally, discussions on why these activities are necessary as part of a NASA mission are included. Finally, examples of how the RBSP E/PO team has carried out some of these activities will be discussed throughout.     

UAVs: the future. [A century of powered flight: 1903-2003]

Unmanned air vehicles (UAV) are assuming a prominent role in aviation and the future may have already arrived. Most of us have heard of the Global Hawk and Predator UAVs, which have been collecting real-time battlefield data without risking loss of life. However, the most amazing performance and avionics can be found in airplane-model-size MiniUAVs and insect-like MicroUAVs still on the drawing board. Meanwhile the all-electric NASA Helios "tower in the sky" is moving ever closer to reality.     

Design of hybrid-electric aircraft with fault-tolerance considerations

The potential benefits of hybrid-electric or all-electric propulsion have led to a growing interest in this topic over the past decade. Preliminary design of propulsion systems and innovative configurations has been extensively discussed in literature, but steps towards higher levels of technological readiness, optimisation algorithms based on reliable weight estimation and simulation-based mission analysis are required. This paper focuses on the integration of a method for evaluating the lateral-directional controllability of an aircraft within a design chain that integrates aero-propulsive interactions, accurate modelling of the fuel system, and mid-fidelity estimation of the structural weight. Furthermore, the present work proposes a strategy for powerplant management in scenarios with an inoperative chain element. Benefits of hybrid-electric propulsion on the design of the vertical tail plane are evaluated involving the analysis of multiple failure scenarios and certification requirements. The proposed application concerns a commuter aircraft.     

A review of advanced turboprop transport aircraft

The application of advanced technologies shows the potential for significant improvement in the fuel efficiency and operating costs of future transport aircraft envisioned for operation in the 1990s time period. One of the more promising advanced technologies is embodied in an advanced turboprop concept originated by Hamilton Standard and NASA and known as the propfan. The propfan concept features a highly loaded multibladed, variable pitch propeller geared to a high pressure ratio gas turbine engine. The blades have high sweepback and advanced airfoil sections to achieve 80 percent propulsive efficiency at M=0.80 cruise speed. Aircraft system studies have shown improvements in fuel efficiency of 15–20 percent for propfan advanced transport aircraft as compared to equivalent turbofan transports. Beginning with the Lockheed C-130 and Electra turboprop aircraft, this paper presents an overview of the evolution of propfan aircraft design concepts and system studies. These system studies include possible civil and military transport applications and data on the performance, community and far-field noise characteristics and operating costs of propfan aircraft design concepts. NASA Aircraft Energy Efficiency (ACEE) program propfan projects with industry are reviewed with respect to system studies of propfan aircraft and recommended flight development programs.     

Today... tomorrow [of multidisciplinary systems of systems]

Some recent or near future examples of multidisciplinary systems of systems are illustrated. They include: upgraded Shuttle avionics; Airbus fly-by-wire; integrated modular electronics; electric automobiles; all-electric aircraft; and JointSTARS system     

Design of safety monitor schemes for a fault tolerant flight control system

For a research aircraft, "conventional" control laws (CLs) are implemented on a "baseline" flight computer (FC) while research CLs are typically housed on a dedicated research computer. Therefore, for an experimental aircraft used to test specific fault tolerant flight control systems, a safety logic scheme is needed to ensure a safe transition from conventional to research CLs (while at nominal conditions) as well as from research CLs at nominal conditions to conditions with "simulated" failures on specific control surfaces. This paper describes the design of such a safety scheme for the NASA Intelligent Flight Control System (IFCS) F-15 Program. The goals of the IFCS F-15 program are to investigate the performance of a set of fault tolerant CLs based on the use of dynamic inversion with neural augmentation. The different transitions are monitored using information relative to flight conditions and controller-related performance criteria. The testing of the scheme is performed with a Simulink-based flight simulation code and interface developed at West Virginia University for the NASA IFCS F-15 aircraft.     

Modern turboprop engines

The turboprop engine has played a major role in short haul commuter aircraft and military transport and patrol aircraft where speed is not critical. In recent years NASA have proposed the application of turboprops, coupled to advanced propellers usually referred to as ‘propfans’, at conventional turbofan speeds. The achievement of this goal would provide significant savings in fuel without sacrifice of flight speed. The paper reviews the past history and current state of development of modern turboprops, noting that there has been very little recent development of high power units. Current trends suggest a shift from the NASA goal away from turboprops to a new breed of engine using the generic name Ultra High Bypass systems. Although the future of the turboprop for high speed transportation may appear dubious, there is no doubt that the turboprop is going to continue to play an increasingly important role in the short haul commuter aircraft market.     

NASA共同研究模型翼身组合体数值模拟研究

采用结构网格求解器WiseManPlus软件,对DPW5提供的NASA共同研究模型CRM翼身组合体构型进行数值模拟研究.采用雷诺平均N-S方程,选择SA一方程湍流模型和SST两方程湍流模型,开展了网格收敛性分析及抖振分析计算研究,评估了该软件对此类民机构型的阻力预测能力.按照DPW5的要求,采用会议统一提供的基准结构网格进行计算分析,研究结果表明,计算的巡航设计点的阻力及大攻角下的气动力系数与试验值吻合较好,达到会议统计分析平均水平.计算结果表明,所采用的结构网格求解器WiseManPlus软件计算精度较高,适用于大型民机高速巡航及抖振现象的数值模拟研究.     

The All-Electric Fighter Airplane Flight Control Issues, Capabilities, and Projections

The prime issues raised in any all-electric airplane discussion are (1) is the electric power system as reliable and trustworthy as a hydraulic power system; (2) can electromechanical flight control actuators perform satisfactorily, i.e., can the performance match that of hydraulic actuators; (3) can redundant electromechanical actuation systems (EMAS) be designed to equal the flight safety reliability of dual tandem hydraulic actuators; and (4) can satisfactory solutions be found or developed for dissipating the heat generated in actuators and power controllers. The first question should be inconsequential since it is assumed that the all-electric aircraft will be equipped with a fly-by-wire (FBW) flight control system (FCS) which is already dependent upon an uninterrupted supply of electrical power. Design studies and hardware already developed show that the answer to question (2) is that EMAS outperform hydraulic actuators, particularly under load. The answer to question (3) is not as clear primarily because the issue has not been addressed in any depth. As posed the answer must be yes, but with the proviso that the weight might be greater than currently predicted. Studies have shown that we can cope with the heat dissipation issue addressed in question (4) in the case of motors and inverter/power controllers. The projections regarding usage of EMAS and the future of the all-electric airplane must be based on the type of vehicle (small subsonic transport, large transport, or military tighter) and the economics involved.     

非对称结构损伤飞机鲁棒容损控制器设计

当飞机发生非对称结构损伤时,飞机的质量、重心位置和气动特性都会发生突变,飞机机体的对称性遭到破坏,致使飞机的横纵向间运动产生强烈的耦合。针对飞机发生非对称结构损伤时导致的飞行控制问题,建立了非对称结构损伤飞机的损伤模型,并基于一种新型鲁棒容损控制策略,采用非线性扩张状态观测器和非线性动态逆相结合的方法,对飞机的姿态控制器进行了设计,兼顾了飞机系统的性能和对损伤的鲁棒性。最后,基于NASA的通用运输机模型,对所设计控制器的控制效果进行了仿真验证。仿真结果表明,设计的姿态控制器有效地抑制了非对称结构损伤给飞机控制系统带来的不确定性和扰动,具有较好的控制性能。     

飞机座舱显示控制界面设计

飞机座舱显示控制系统作为人机接口,一直是航空工效学关注的对象,提高飞机座舱显示控制系统的可视性和方便操作性,是其设计时所要追求的目标。综合近年来飞机座舱显示控制界面的相关研究现状,创建一种飞机座舱显示控制界面设计方法,并探讨软件设计中涉及到的一些关键技术。该方法集成在 C++系统 中,在飞机座舱设计的各个阶段分别引入飞行员三维人体几何模型和运动学模型;结合视景仿真建模理论和相 关软件,实现飞行视景及座舱显示控制界面的开发;提出飞机座舱显示控制界面设计的综合评价方法,以及各 种评价指标的筛选与评价体系的确立。该显示控制界面设计方法能够通过模拟飞行员的操作动作与计算视 角、可达性、操纵力等参数,较好地反映出飞行员的运动学和动力学特性,提高了界面友好性、操作直观性、简便性。     

一种检测机场跑道辅助飞机着陆的系统设计

跑道作为机场的关键设施,是飞机着陆和减速滑行的区域,通过视觉定位方法计算飞机相对跑道的位置,可以作为辅助飞机快速平稳着陆的一种思路。视觉传感器所需成本较低,对安装环境要求不高,本文旨在设计一个仅靠视觉传感器对飞机进行定位的辅助着陆系统,运用目标检测和视觉定位两个模型,计算飞机相对跑道的位置。首先搭建出等比例微缩的机场跑道模型,视觉传感器产生运动模拟飞机飞行路径,目标检测模型通过机载视觉传感器获取的图像识别出跑道区域,随后视觉定位模型提取图像中跑道区域特征点,计算飞机相对跑道的位置。分别对目标检测和视觉定位两部分的实现原理及难点进行阐述,尝试将目标检测和视觉定位结合起来实现飞机降落时的定位,描述辅助着陆系统设计的整体思路。