Electronic/electric technology benefits study

The benefits and payoffs of advanced electronic/electric technologies were investigated for three types of aircraft. The technologies, evaluated in each of the three airplanes, included advanced flight controls, advanced secondary power, advanced avionic complements, new cockpit displays, and advanced air traffic control techniques. For the advanced flight controls, the near term considered relaxed static stability (RSS) with mechanical backup. The far term considered an advanced fly by wire system for a longitudinally unstable airplane. In the case of the secondary power systems, trades were made in two steps: in the near term, engine bleed was eliminated; in the far term bleed air, air plus hydraulics were eliminated. Using three commercial aircraft, in the 150, 350, and 700 passenger range, the technology value and pay-offs were quantified, with emphasis on the fiscal benefits. Weight reductions deriving from fuel saving and other system improvements were identified and the weight savings were cycled for their impact on TOGW (takeoff gross weight) and upon the performance of the airframes/engines. Maintenance, reliability, and logistic support were the other criteria

Energy efficient transport technology: Program summary and bibliography

The Energy Efficient Transport (EET) Program began in 1976 as an element of the NASA Aircraft Energy Efficiency (ACEE) Program. The EET Program and the results of various applications of advanced aerodynamics and active controls technology (ACT) as applicable to future subsonic transport aircraft are discussed. Advanced aerodynamics research areas included high aspect ratio supercritical wings, winglets, advanced high lift devices, natural laminar flow airfoils, hybrid laminar flow control, nacelle aerodynamic and inertial loads, propulsion/airframe integration (e.g., long duct nacelles) and wing and empennage surface coatings. In depth analytical/trade studies, numerous wind tunnel tests, and several flight tests were conducted. Improved computational methodology was also developed. The active control functions considered were maneuver load control, gust load alleviation, flutter mode control, angle of attack limiting, and pitch augmented stability. Current and advanced active control laws were synthesized and alternative control system architectures were developed and analyzed. Integrated application and fly by wire implementation of the active control functions were design requirements in one major subprogram. Additional EET research included interdisciplinary technology applications, integrated energy management, handling qualities investigations, reliability calculations, and economic evaluations related to fuel savings and cost of ownership of the selected improvements

Advanced flight control system study

The architecture, requirements, and system elements of an ultrareliable, advanced flight control system are described. The basic criteria are functional reliability of 10 to the minus 10 power/hour of flight and only 6 month scheduled maintenance. A distributed system architecture is described, including a multiplexed communication system, reliable bus controller, the use of skewed sensor arrays, and actuator interfaces. Test bed and flight evaluation program are proposed

Advanced flight control system study

A fly by wire flight control system architecture designed for high reliability includes spare sensor and computer elements to permit safe dispatch with failed elements, thereby reducing unscheduled maintenance. A methodology capable of demonstrating that the architecture does achieve the predicted performance characteristics consists of a hierarchy of activities ranging from analytical calculations of system reliability and formal methods of software verification to iron bird testing followed by flight evaluation. Interfacing this architecture to the Lockheed S-3A aircraft for flight test is discussed. This testbed vehicle can be expanded to support flight experiments in advanced aerodynamics, electromechanical actuators, secondary power systems, flight management, new displays, and air traffic control concepts

Urban and extra-urban hybrid vehicles: a technological review

Pollution derived from transportation systems is a worldwide, timelier issue than ever. The abatement actions of harmful substances in the air are on the agenda and they are necessary today to safeguard our welfare and that of the planet. Environmental pollution in large cities is approximately 20% due to the transportation system. In addition, private traffic contributes greatly to city pollution. Further, “vehicle operating life” is most often exceeded and vehicle emissions do not comply with European antipollution standards. It becomes mandatory to find a solution that respects the environment and, realize an appropriate transportation service to the customers. New technologies related to hybrid –electric engines are making great strides in reducing emissions, and the funds allocated by public authorities should be addressed. In addition, the use (implementation) of new technologies is also convenient from an economic point of view. In fact, by implementing the use of hybrid vehicles, fuel consumption can be reduced. The different hybrid configurations presented refer to such a series architecture, developed by the researchers and Research and Development groups. Regarding energy flows, different strategy logic or vehicle management units have been illustrated. Various configurations and vehicles were studied by simulating different driving cycles, both European approval and homologation and customer ones (typically municipal and university). The simulations have provided guidance on the optimal proposed configuration and information on the component to be used

The design of more-electric engine power systems

The More-Electric Aircraft (MEA) concept is now a well-established concept, following its introduction and development over the previous couple of decades. MEA systems are underpinned by state-of-the-art technologies to realise the reduction of CO2 emissions and increased the effectiveness of on-board power transmission. The More-Electric Engine (MEE) concept is increasingly being seen as a complementary solution for MEA applications. Within this concept, the engine auxiliary systems such as fuel pumps, oil pumps and actuation systems will be replaced by electrically driven equivalents and power will be extracted from multiple different engine shafts for electrical generation, with the potential to achieve significant fuel savings. However, with these changes, a dedicated high-integrity and flexibly reconfigurable MEE multiple-channel power architecture is required. When designing a multiple-channel power architecture for MEE，it should comply with relevant power system design certification standards, requiring the application of a multi-disciplinary design methodology. In this thesis, key design certification and airworthiness standards are reviewed in order to identify those applicable to MEE design. Combining these with traceable qualitative and quantitative design logic, the first power system design rule set for MEE power system architecture baselining is established. Building on this foundational knowledge base, candidate novel multiple-channel power architectures are proposed and evaluated. These studies determine that a high degree of controllability and redundancy is key to achieving high system reliability and resilience in MEE power system architectures. In addition, a review of the research literature in this thesis is shown to reveal a shortage of proposed design and optimisation processes for flexible and redundant MEE-type power systems, making it difficult to maximise the design value of a feasible solution. As interdisciplinary and multi-system design processes can be time-consuming and laborious, this thesis instead presents a concurrent design (Co-design) methodology, addressing both MEE power architecture concepts and power management functions. This novel design process includes an initial coarse optimisation to determine the design space boundaries and exclude unsuitable and over-designed solutions for further detailed design, reducing design iterations. A subsequent collaborative synthesis stage for the concurrent design process is then proposed, in which fault scenario case studies and load shedding factor are used to verify the robustness of the combined MEE architecture and power management solutions to off-nominal operating conditions. This enables the refinement of the solution-space by using the simulated results to highlight the areas of the MEE power architecture that can be further optimised, demonstrating the benefits of knowledge-based collaborative design as a process for multi-criteria design. The contributions to the design of MEE power systems architectures presented in this thesis hence provide end-to-end value to the academic and industrial research community in the formation and design of new MEE concepts, with wider application to technologically-adjacent applications (such as hybrid electric aircraft, or high-integrity dc microgrids) also possible.The More-Electric Aircraft (MEA) concept is now a well-established concept, following its introduction and development over the previous couple of decades. MEA systems are underpinned by state-of-the-art technologies to realise the reduction of CO2 emissions and increased the effectiveness of on-board power transmission. The More-Electric Engine (MEE) concept is increasingly being seen as a complementary solution for MEA applications. Within this concept, the engine auxiliary systems such as fuel pumps, oil pumps and actuation systems will be replaced by electrically driven equivalents and power will be extracted from multiple different engine shafts for electrical generation, with the potential to achieve significant fuel savings. However, with these changes, a dedicated high-integrity and flexibly reconfigurable MEE multiple-channel power architecture is required. When designing a multiple-channel power architecture for MEE，it should comply with relevant power system design certification standards, requiring the application of a multi-disciplinary design methodology. In this thesis, key design certification and airworthiness standards are reviewed in order to identify those applicable to MEE design. Combining these with traceable qualitative and quantitative design logic, the first power system design rule set for MEE power system architecture baselining is established. Building on this foundational knowledge base, candidate novel multiple-channel power architectures are proposed and evaluated. These studies determine that a high degree of controllability and redundancy is key to achieving high system reliability and resilience in MEE power system architectures. In addition, a review of the research literature in this thesis is shown to reveal a shortage of proposed design and optimisation processes for flexible and redundant MEE-type power systems, making it difficult to maximise the design value of a feasible solution. As interdisciplinary and multi-system design processes can be time-consuming and laborious, this thesis instead presents a concurrent design (Co-design) methodology, addressing both MEE power architecture concepts and power management functions. This novel design process includes an initial coarse optimisation to determine the design space boundaries and exclude unsuitable and over-designed solutions for further detailed design, reducing design iterations. A subsequent collaborative synthesis stage for the concurrent design process is then proposed, in which fault scenario case studies and load shedding factor are used to verify the robustness of the combined MEE architecture and power management solutions to off-nominal operating conditions. This enables the refinement of the solution-space by using the simulated results to highlight the areas of the MEE power architecture that can be further optimised, demonstrating the benefits of knowledge-based collaborative design as a process for multi-criteria design. The contributions to the design of MEE power systems architectures presented in this thesis hence provide end-to-end value to the academic and industrial research community in the formation and design of new MEE concepts, with wider application to technologically-adjacent applications (such as hybrid electric aircraft, or high-integrity dc microgrids) also possible

Shuttle Ground Operations Efficiencies/Technologies (SGOE/T) study. Volume 2: Ground Operations evaluation

The Ground Operations Evaluation describes the breath and depth of the various study elements selected as a result of an operational analysis conducted during the early part of the study. Analysis techniques used for the evaluation are described in detail. Elements selected for further evaluation are identified; the results of the analysis documented; and a follow-on course of action recommended. The background and rationale for developing recommendations for the current Shuttle or for future programs is presented

Aircraft electromagnetic compatibility

Illustrated are aircraft architecture, electromagnetic interference environments, electromagnetic compatibility protection techniques, program specifications, tasks, and verification and validation procedures. The environment of 400 Hz power, electrical transients, and radio frequency fields are portrayed and related to thresholds of avionics electronics. Five layers of protection for avionics are defined. Recognition is given to some present day electromagnetic compatibility weaknesses and issues which serve to reemphasize the importance of EMC verification of equipment and parts, and their ultimate EMC validation on the aircraft. Proven standards of grounding, bonding, shielding, wiring, and packaging are laid out to help provide a foundation for a comprehensive approach to successful future aircraft design and an understanding of cost effective EMC in an aircraft setting

Electrical power generation in aircraft: review, challenges and opportunities

The constant growth of air traffic, the demand for performance optimization and the need for decreasing both operating and maintenance costs have encouraged the aircraft industry to move towards more electric solutions. As a result of this trend, electric power required on board of aircraft has significantly increased through the years, causing major changes in electric power system architectures. Considering this scenario, the paper gives a review about the evolution of electric power generation systems in aircraft. The major achievements are highlighted and the rationale behind some significant developments discussed. After a brief historical overview of the early DC generators (both wind- and engine-driven), the reasons which brought the definitive passage to the AC generation, for larger aircraft, are presented and explained. Several AC generation systems are investigated with particular attention being focused on the voltage levels and the generator technology. Further, examples of commercial aircraft implementing AC generation systems are provided. Finally, the trends towards modern generation systems are also considered giving prominence to their challenges and feasibility