Edwards Air Force Base, CA, United States
Edwards Air Force Base, CA, United States

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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.

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.

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.

Fecko M.,Applied Communication science | Chang K.,Applied Communication science | Cichocki A.,Applied Communication science | Kim H.,Applied Communication science | And 11 more authors.
Proceedings of the International Telemetering Conference | Year: 2014

In an iNET telemetry network, Link Manager (LM) dynamically allocates capacity to radio links to achieve desired QoS guarantees. Under the T&E S&T iMANPOL program, we developed an enhanced capacity allocation algorithm that can better cope with severe congestion and misbehaving users and traffic flows. We compare the E-LM with the LM baseline algorithm (B-LM), which employs priority-weighted allocation. The B-LM is expected to perform well for the majority of traffic patterns, but does not prevent an ill-behaved traffic class from causing excessive latency on other radio links. The E-LM ensures that each class has a "guaranteed" portion of the total available bandwidth that is proportional to the weight of the class. If the traffic loading of a class is lower than its quota, the difference can be flexibly shared by other classes across multiple links. If the traffic loading of a class is higher than its quota, its demand may still be satisfied, provided that the capacity is not taken away from well-behaved traffic classes that stay below their quotas. The qualitative analysis shows the E-LM provides lower latencies for the well-behaved links in overloading conditions and increases the overall system throughput when the traffic is unbalanced. We conducted extensive experiments to confirm that analysis, with the E-LM reducing latency of well-behaved flows up to 90%, and increasing overall throughput up to 65% over the B-LM.

Baumann E.,NASA | Pahle J.W.,NASA | Davis M.C.,NASA | White J.T.,Tybrin Corporation
Journal of Spacecraft and Rockets | Year: 2010

NASA has flight tested a flush airdata sensing system on the Hyper-X research vehicle (X-43A) at hypersonic speeds during the course of two successful flights. The flush airdata sensing system was calibrated to operate between Mach 3 and Mach 8, and flight-test data were collected between Mach 1 and Mach 10. The flush airdata sensing system acquired pressure data from surface-mounted ports and generated a real-time angle-of-attack estimate onboard the X-43A. The collected data were primarily intended to evaluate the flush airdata sensing system performance, and the estimated angle of attack was used by the flight control algorithms on the X-43A for only a portion of the first successful flight. A separate set of algorithm calibrations based on wind-tunnel data was found to match the flight results better than the analytically derived calibrations at the lower Mach numbers. This paper provides an overview of the flush airdata sensing system and angle-of-attack estimation algorithms, the in-flight angle-of-attack estimation algorithm performance, and the comparisons between flight-test data, analytical predictions, and wind-tunnel results. Flight-test results indicate that the flush airdata sensing system is a viable technique for generating a real-time angle-of-attack estimate at hypersonic velocities.

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.

Fecko M.,Applied Communication science | Chang K.,Applied Communication science | Cichocki A.,Applied Communication science | Wong L.,Applied Communication science | And 4 more authors.
Proceedings of the International Telemetering Conference | Year: 2015

We developed priority-aligned flow control between the queuing system and the radio for IPbased telemetry systems. The approach provides the unified flow control across all nodes and traffic classes in telemetry links to better regulate bandwidth usage without creating oscillations. It combines multiple features: Volume-based flow control ensures consistency between a traffic queue's drain rate and the TDMA slot allocations for this queue. The allocations are translated into the number of packets to be sent to the radio from the router for each QoS class and test mission. In the case of iNET, the necessary capacity allocations are provided by the Link Manager on the ground. Fine-grained queue management allows flow control algorithms to adjust dynamically multiple parameters at the Traffic Engineering Queues as needed. Router-radio interface enhances the existing IETF standard Data Link Exchange Protocol (DLEP) to provide the signaling required for our solution. We defined the queue throughput shortage as the key evaluation metric. Our approach performed significantly better in comparison with the coarse-grained queue control available in Linux kernel. When averaged across links/queues, the reduction was 2-6% and 4-28% for high (8Mbps) and low (1Mbps) channel capacities, respectively. When averaged across multiple channel capacities, the maximum per-queue shortage was reduced from 47% to 4.5%.

Fladeland M.,NASA | Sumich M.,NASA | Lobitz B.,California State University, Monterey Bay | Kolyer R.,NASA | And 6 more authors.
Geocarto International | Year: 2011

Earth scientists use unmanned aerial vehicles (UAVs) to enable measurements and observations that cannot be collected by manned aircraft such as the ER-2, DC-8 or B-200. Science community interest in UAVs to date has largely been focused on the larger class of UAV such as the Global Hawk and Predator, because of the large mass of legacy airborne science instruments. With the continued miniaturization of instruments and data systems and the rapid pace of development of all classes of UAV world-wide during the past decade, smaller classes of UAV are now capable of providing important science measurements and observations. Small (<50 lbs GTOW) and medium-class UAV (>500 lbs GTOW) complement the larger platforms by enabling in situ measurements of the atmospheric boundary layer with low-altitude remote sensing or air sampling, while providing a relatively low cost platform for storm penetration and dangerous, remote missions where the system may not return. The National Aeronautics and Space Administration (NASA) Sensor Integrated Environmental Remote Research Aircraft (SIERRA) project at the Ames Research Center (ARC) has demonstrated the utility of a medium class unmanned aircraft for providing science measurements in remote and dangerous environments using active, passive and in situ earth science instrument payloads. This article describes the SIERRA project, details past and future missions, and discusses the primary requirements for small and medium class UAV.

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.

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