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Edwards Air Force Base, CA, United States

Page J.A.,Wyle | Hobbs C.M.,Wyle | Haering Jr. E.A.,NASA | Maglieri D.J.,Eagle Aeronautics Inc. | And 5 more authors.
51st AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition 2013 | Year: 2013

This paper documents the May 2011 experimental flight test acoustic and meteorological measurements gathered as part of the Superboom Caustic Analysis and Measurement Program (SCAMP). The SCAMP team, led by Wyle and NASA includes partners from the Boeing Company, Pennsylvania State University, Gulfstream Aerospace, Eagle Aeronautics and Central Washington University and collaborators from Cessna, Northrop-Grumman and Nagoya University. The objectives of the SCAMP research program are to validate, via flight test measurements, models for sonic boom signatures in and around focal zones, and to apply these models to predict focus booms for low-boom aircraft designs. This experiment required precision flight of an F-18B executing different maneuvers to create focused sonic booms. The experiment was designed to capture concurrent F-18B onboard flight data instrumentation, high-fidelity, ground-based and elevated acoustic data, and surface and upper air meteorological measurements. The ground-based acoustic instrumentation array was located at the Cuddeback Air-to-Ground Gunnery Range, California. Primary acoustic measurements were on-track, in a plane of symmetry corresponding to the formal theory. Off-track measurements were achieved by flying the aircraft along a path laterally displaced from the linear measurement array. Under SCAMP, a process was developed whereby a trained measurement team provided immediate feedback based on aural observations to the On-Site Test Director. In real time, desired changes of the F-18B way points and flight paths were then relayed to the pilot, thereby improving focused boom measurement captures and data outcomes. During the two weeks of flight operations, 70 sonic boom events were captured by the instrumentation systems. © 2013 by Juliet A. Page. Source

Hanson C.,NASA | Schaefer J.,NASA | Burken J.J.,NASA | Johnson M.,Tybrin Corporation | Nguyen N.,NASA
AIAA Guidance, Navigation, and Control Conference 2011 | Year: 2011

National Aeronautics and Space Administration (NASA) researchers have conducted a series of flight experiments designed to study the effects of varying levels of adaptive controller complexity on the performance and handling qualities of an aircraft under various simulated failure or damage conditions. A baseline, nonlinear dynamic inversion controller was augmented with three variations of a model reference adaptive control design. The simplest design consisted of a single adaptive parameter in each of the pitch and roll axes computed using a basic gradient-based update law. A second design was built upon the first by increasing the complexity of the update law. The third and most complex design added an additional adaptive parameter to each axis. Flight tests were conducted using NASA's Full-scale Advanced Systems Testbed, a highly modified F-18 aircraft that contains a research flight control system capable of housing advanced flight controls experiments. Each controller was evaluated against a suite of simulated failures and damage ranging from destabilization of the pitch and roll axes to significant coupling between the axes. Two pilots evaluated the three adaptive controllers as well as the non-adaptive baseline controller in a variety of dynamic maneuvers and precision flying tasks designed to uncover potential deficiencies in the handling qualities of the aircraft, and adverse interactions between the pilot and the adaptive controllers. The work was completed as part of the Integrated Resilient Aircraft Control Project under NASA's Aviation Safety Program. © Protection in the United States. Source

Smearcheck M.A.,Air Force Institute of Technology | Veth M.J.,Air Force Institute of Technology | Zangaro C.,Tybrin Corporation
Institute of Navigation - International Technical Meeting 2010, ITM 2010 | Year: 2010

This paper investigates the navigation accuracy achievable by fusing various combinations of sensors of differing modalities to be used in a next generation time-space position information (TSPI) system for the Air Force Flight Test Center (AFFTC). These sensors include inertial, GPS, vehicle-mounted EO/IR cameras, barometric altimeter, laser ranging sensors (both airborne and ground located), ground-based tracking radars, and ground-based theodolites. Because the AFFTC's updated TSPI sensor package will be deployed at a test range located in the Mojave Desert, the aforementioned sensors can take advantage of environment specific factors to improve performance including a stable climate, limited precipitation, natural non-changing terrain features, artificial pre-surveyed landmarks, and the capability to install ground based sensors. In order to perform this study, four key areas were addressed: investigation of sensors suitable for a next-generation TSPI system, modeling of those sensors, development of data simulation software, and a sensitivity analysis with various sensor combinations. A discussion of viable onboard and ground-based sensors and how they may be modeled and used to generate TSPI data is provided. Data generation software is explained including sensor deployment, generation of simulation measurements based on environmental constraints, and optical feature tracking. Results are presented in the form of a sensitivity analysis that specifies the expected accuracy and navigation performance of different sensing packages. The minimal TSPI sensor package capable of meeting accuracy requirements is identified. Source

Haering Jr. E.A.,NASA | Cliatt II L.J.,NASA | Delaney Jr. M.M.,NASA | Plotkin K.J.,Wyle | And 2 more authors.
51st AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition 2013 | Year: 2013

Successful execution of the flight phase of the Superboom Caustic Analysis and Measurement Project (SCAMP) required accurate placement of focused sonic booms on an array of prepositioned ground sensors. While the array was spread over a 10,000-ft-long area, this is a relatively small region when considering the speed of a supersonic aircraft and sonic boom ray path variability due to shifting atmospheric conditions and aircraft trajectories. Another requirement of the project was to determine the proper position for a microphone-equipped motorized glider to intercept the sonic boom caustic, adding critical timing to the constraints. Variability in several inputs to these calculations caused some shifts of the focus away from the optimal location. Reports of the sonic booms heard by persons positioned amongst the array were used to shift the focus closer to the optimal location for subsequent passes. This paper describes the methods and computations used to place the focused sonic boom on the SCAMP array and gives recommendations for their accurate placement by future quiet supersonic aircraft. For the SCAMP flights, 67% of the foci were placed on the ground array with measured positions within a few thousand feet of computed positions. Among those foci with large caustic elevation angles, 96% of foci were placed on the array, and measured positions were within a few hundred feet of computed positions. The motorized glider captured sonic booms on 59% of the passes when the instrumentation was operating properly. Source

Schaefer J.,NASA | Hanson C.,NASA | Johnson M.A.,Tybrin Corporation | Nguyen N.,NASA
AIAA Guidance, Navigation, and Control Conference 2011 | Year: 2011

Three model reference adaptive controllers (MRAC) with varying levels of complexity were evaluated on a high performance jet aircraft and compared along with a baseline nonlinear dynamic inversion controller. The handling qualities and performance of the controllers were examined during failure conditions that induce coupling between the pitch and roll axes. Results from flight tests showed with a roll to pitch input coupling failure, the handling qualities went from Level 2 with the baseline controller to Level 1 with the most complex MRAC tested. A failure scenario with the left stabilator frozen also showed improvement with the MRAC. Improvement in performance and handling qualities was generally seen as complexity was incrementally added; however, added complexity usually corresponds to increased verification and validation effort required for certification. The tradeoff between complexity and performance is thus important to a controls system designer when implementing an adaptive controller on an aircraft. This paper investigates this relation through flight testing of several controllers of vary complexity. Source

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