342 research outputs found

    Engine Yaw Augmentation for Hybrid-Wing-Body Aircraft via Optimal Control Allocation Techniques

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    Asymmetric engine thrust was implemented in a hybrid-wing-body non-linear simulation to reduce the amount of aerodynamic surface deflection required for yaw stability and control. Hybrid-wing-body aircraft are especially susceptible to yaw surface deflection due to their decreased bare airframe yaw stability resulting from the lack of a large vertical tail aft of the center of gravity. Reduced surface deflection, especially for trim during cruise flight, could reduce the fuel consumption of future aircraft. Designed as an add-on, optimal control allocation techniques were used to create a control law that tracks total thrust and yaw moment commands with an emphasis on not degrading the baseline system. Implementation of engine yaw augmentation is shown and feasibility is demonstrated in simulation with a potential drag reduction of 2 to 4 percent. Future flight tests are planned to demonstrate feasibility in a flight environment

    Modeling and flight testing of differential thrust and thrust vectoring on a small UAV

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    The primary objectives of this research are to mathematically model the propulsion forces applied to the aircraft during nominal, differential thrust, and thrust vectored flight configurations, and verify this modeling through simulation and flight testing experiments. This thesis outlines the modeling process, simulator development, design, and implementation of a propulsion assisted control system for the WVU Flight Control Systems Lab (FCSL) research aircraft. Differential thrust and thrust vectoring introduce additional propulsive terms in the aircraft force equations that are not present when the thrust line passes through the center of gravity. These additional forces were modeled and incorporated into a simulator of the research aircraft. The effects from differential thrust were small and difficult to quantify. The thrust vectoring effects were also found to be small with the elevator having significantly more pitch control over the vectored motors at the simulated flight conditions.;Differential thrust was implemented using the on-board computer to command a different thrust level to each motor. The desired thrust differential was programed into a flight scheme based on simulation data, and activated during flight via a control switch on the transmitter. The thrust vectoring mechanism was designed using SolidWorksRTM, built and tested outside of the aircraft, and finally incorporated into the aircraft. A high torque servo was used to rotate the motor mounting bar and vector the motors to a desired deflection. Utilizing this mechanism, the thrust vectoring was flight tested, mimicking scenarios tested in simulation. The signal to noise ratio was very low, making it difficult to identify the small changes in the aircraft parameters caused by the vectored thrust

    The Case for Intelligent Propulsion Control for Fast Engine Response

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    Damaged aircraft have occasionally had to rely solely on thrust to maneuver as a consequence of losing hydraulic power needed to operate flight control surfaces. The lack of successful landings in these cases inspired research into more effective methods of utilizing propulsion-only control. That research demonstrated that one of the major contributors to the difficulty in landing is the slow response of the engines as compared to using traditional flight control. To address this, research is being conducted into ways of making the engine more responsive under emergency conditions. This can be achieved by relaxing controller limits, adjusting schedules, and/or redesigning the regulators to increase bandwidth. Any of these methods can enable faster response at the potential expense of engine life and increased likelihood of stall. However, an example sensitivity analysis revealed a complex interaction of the limits and the difficulty in predicting the way to achieve the fastest response. The sensitivity analysis was performed on a realistic engine model, and demonstrated that significantly faster engine response can be achieved compared to standard Bill of Material control. However, the example indicates the need for an intelligent approach to controller limit adjustment in order for the potential to be fulfilled

    An overview of integrated flight-propulsion controls flight research on the NASA F-15 research airplane

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    The NASA Dryden Flight Research Center has been conducting integrated flight-propulsion control flight research using the NASA F-15 airplane for the past 12 years. The research began with the digital electronic engine control (DEEC) project, followed by the F100 Engine Model Derivative (EMD). HIDEC (Highly Integrated Digital Electronic Control) became the umbrella name for a series of experiments including: the Advanced Digital Engine Controls System (ADECS), a twin jet acoustics flight experiment, self-repairing flight control system (SRFCS), performance-seeking control (PSC), and propulsion controlled aircraft (PCA). The upcoming F-15 project is ACTIVE (Advanced Control Technology for Integrated Vehicles). This paper provides a brief summary of these activities and provides background for the PCA and PSC papers, and includes a bibliography of all papers and reports from the NASA F-15 project

    Adaptive Failure Compensation for Aircraft Tracking Control Using Engine Differential Based Model

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    An aircraft model that incorporates independently adjustable engine throttles and ailerons is employed to develop an adaptive control scheme in the presence of actuator failures. This model captures the key features of aircraft flight dynamics when in the engine differential mode. Based on this model an adaptive feedback control scheme for asymptotic state tracking is developed and applied to a transport aircraft model in the presence of two types of failures during operation, rudder failure and aileron failure. Simulation results are presented to demonstrate the adaptive failure compensation scheme

    Integration, Testing and Validation, of a Small Hybrid-Electric Remotely-Piloted Aircraft

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    Parallel hybrid-electric technology offers a wide variety of new mission capabilities including low-observable loiter operations and increased fuel efficiency for small remotely-piloted aircraft. This research focused on the integration, validation, and testing of a hybrid-electric propulsion system consisting of commercially available components to fabricate a small remotely-piloted aircraft capable of extended low-observable operation. Three novel aspects contributed to the success of the design: optimization of the propulsive components to the integrated system, torque control of the components for additive power, and a one-way bearing/ pulley mechanism (patent pending) mechanically linking the hybrid system components. To the knowledge of the author at the time of publication, this project represents the first functional parallel hybrid-electric propulsion system for a remotely-piloted aircraft. The integration phase entailed the selection, testing, and assembly of components chosen based on prior design simulations. The propulsion system was retrofitted onto a glider airframe with a 12 ft wingspan and a maximum takeoff weight of 35 lbs, also based on the initial design simulations. During the validation and testing phases, results from bench, ground, and flight testing were compared to the design simulations. The designed propulsion system was well matched to the power estimates of the design simulations. Bench and ground tests demonstrated that hybrid mode, electric only mode, combustion only mode, and regeneration mode are fully functional. Comparison of bench test results to an engine only variant of the airframe indicate the HE system is capable of flying the aircraft

    An Electronic Workshop on the Performance Seeking Control and Propulsion Controlled Aircraft Results of the F-15 Highly Integrated Digital Electronic Control Flight Research Program

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    Flight research for the F-15 HIDEC (Highly Integrated Digital Electronic Control) program was completed at NASA Dryden Flight Research Center in the fall of 1993. The flight research conducted during the last two years of the HIDEC program included two principal experiments: (1) performance seeking control (PSC), an adaptive, real-time, on-board optimization of engine, inlet, and horizontal tail position on the F-15; and (2) propulsion controlled aircraft (PCA), an augmented flight control system developed for landings as well as up-and-away flight that used only engine thrust (flight controls locked) for flight control. In September 1994, the background details and results of the PSC and PCA experiments were presented in an electronic workshop, accessible through the Dryden World Wide Web (http://www.dfrc.nasa.gov/dryden.html) and as a compact disk

    Spinoff, 1976

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    This report is divided into three sections: 1. The Research Payoff, 2. Technology Twice Used, and 3. Technology Utilization at Work. The first describes a wide variety of current space spinoffs of use in business or personal life, as well as the space explorations from which they have been derived. The second provides information on specific examples of technology transfer that are typical of the spinoffs resulting from NASA's Technology Utilization Program. The third briefly describes the different activities of the Technology Utilization Office, all of which have as their purpose the profitable utilization of aerospace technology

    Aeronautical engineering: A continuing bibliography with indexes (supplement 272)

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    This bibliography lists 719 reports, articles, and other documents introduced into the NASA scientific and technical information system in November, 1991. Subject coverage includes: design, construction and testing of aircraft and aircraft engines; aircraft components, equipment, and systems; ground support systems; and theoretical and applied aspects of aerodynamics and general fluid dynamics

    Design, analysis, and control of large transport aircraft utilizing engine thrust as a backup system for the primary flight controls

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    A review of accidents that involved the loss of hydraulic flight control systems serves as an introduction to this project. In each of the accidents--involving transport aircraft such as the DC-10, the C-5A, the L-1011, and the Boeing 747--the flight crew attempted to control the aircraft by means of thrust control. Although these incidents had tragic endings, in the absence of control power due to primary control system failure, control power generated by selective application of engine thrust has proven to be a viable alternative. NASA Dryden has demonstrated the feasibility of controlling an aircraft during level flight, approach, and landing conditions using an augmented throttles-only control system. This system has been successfully flown in the flight test simulator for the B-720 passenger transport and the F-15 air superiority fighter and in actual flight tests for the F-15 aircraft. The Douglas Aircraft Company is developing a similar system for the MD-11 aircraft. The project's ultimate goal is to provide data for the development of thrust control systems for mega-transports (600+ passengers)
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