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Current NIA Graduate Student: Nelson Guerreiro |
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Graduate Student:Nelson Guerreiro, Ph.D. Candidate, University of Maryland
Research Project: Lift Distribution Control Using Spatially Distributed Actuators and Sensors
University Advisor: Dr. James E. Hubbard, Jr., Aerospace Engineering, University of Maryland
Drag is an important parameter to consider when evaluating the performance of an aircraft. The drag produced by an aircraft must be offset by engine power to maintain steady, level flight. As a result, the drag affects an aircraft’s performance in areas such as: fuel consumption, power required, range, endurance, loiter time, etc… In this research, the concept of reducing the drag of an Unmannned Aerial Vehicle (UAV) through the use of trailing edge morphing is explored.
A considerable amount of the drag produced during slow flight of most aircraft, possibly 50 percent or more, can be attributed to induced drag. From aerodynamic theory, the induced drag cannot be eliminated altogether, since it is a function of the lift produced by the aircraft. However, induced drag is also inversely proportional to the wing aspect ratio and the wing span efficiency factor. Aerodynamic theory also states that an elliptical lift distribution yields a span efficiency factor of one and, thus, minimal induced drag for a given lift coefficient and aspect ratio. Trailing edge morphing is used in this research to closely reproduce an elliptical lift distribution on a non-elliptical wing planform of a UAV.
Morphing is achieved through the use of spatially distributed actuators on the trailing edge of a UAV’s main wing. The actuators’ spatial distribution is optimized, using extensive aerodynamic analysis, for minimal control effort in producing an elliptical lift distribution. Co-located conformal sensors are designed with an appropriate chord-wise electrode aperture to measure lift and drag produced at each spanwise sensor location. These distributed parameter sensors provide the feedback required for closed-loop control to maintain an elliptical lift distribution and minimize induced drag in all flight conditions.
Wind Tunnel data of morphing wing configurations is used to build non-linear dynamics models with non-linear controls influence functions that allow for the development of distributed parameter controllers. Simulations can be performed for any specified aircraft mission and compared with data obtained from aircraft flight testing. Data for the morphing wing configuration is also compared against data obtained from a conventional wing to assess performance gains.
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