The Experts below are selected from a list of 1770 Experts worldwide ranked by ideXlab platform
James E. Murray - One of the best experts on this subject based on the ideXlab platform.
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Analysis of mountain wave 3D wind fields in the Andes derived from high-altitude Sailplane flights
Technical Soaring, 2017Co-Authors: Rick P. Millane, Ni Zhang, Einar Enevoldson, James E. MurrayAbstract:Mountain lee waves are of importance in meteorology since they produce drag that affects the general circulation, and can influence windstorms, clear-air turbulence and ozone abundance. Since mountain waves are used routinely by Sailplane pilots, data collected during wave flights are potentially useful for studying the structure of mountain waves. We have previously described methods for determining 3D wind velocities in mountain waves from limited Sailplane flight data. These methods are applied to data from a high-altitude Sailplane flight in the lee of the Andes that reached an altitude of over 15,000 m, well into the stratosphere, allowing a unique kind of in-situ observation of stratospheric mountain waves. The derived wind fields show parts of the wave structure in the troposphere and the stratosphere, and are compared with other observational data. Thus, a minimally instrumented Sailplane can provide useful data for mountain wave research.
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Determining wind fields in atmospheric mountain waves using Sailplane flight data
Image Reconstruction from Incomplete Data VII, 2012Co-Authors: Ni Zhang, Rick P. Millane, Einar Enevoldson, James E. MurrayAbstract:The problem of estimating wind velocities from limited flight data recordings is considered, with application to Sailplane flights in high-altitude atmospheric mountain waves. Sailplane flight recorders routinely measure only GPS position and the problem is highly underdetermined. The nature of this problem is studied and a maximum a posteriori estimator is developed using prior information on the wind velocity and the Sailplane airspeed and heading. The method is tested by simulation and by application to Sailplane flight data.
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Measuring 3DWind Fields in MountainWaves Using Sailplane Flight Data
Technical Soaring, 2012Co-Authors: Ni Zhang, Rick P. Millane, Einar Enevoldson, James E. MurrayAbstract:Mountain lee waves are of considerable interest in meteorology and also are used routinely by Sailplane pilots as a source of lift for high-attitude and long-distance flights. Data collected during wave flights therefore are potentially useful for studying the structure of mountain waves. Novel methods are described for determining three-dimensional wind velocities in mountain waves using limited data from Sailplane flights. Results are presented for application of the methods to data from a flight in the Sierra Nevada mountain wave. Presented at the XXX OSTIV Congress, Szeged, Hungary, 28 July – 4 August 2010
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measuring 3d wind fields in mountain waves using Sailplane flight data
2012Co-Authors: Ni Zhang, Rick P. Millane, Einar Enevoldson, James E. MurrayAbstract:Mountain lee waves are of considerable interest in meteorology and also are used routinely by Sailplane pilots as a source of lift for high-attitude and long-distance fligh ts. Data collected during wave flights therefore are potentially useful for studying the structure of mountain waves. Novel methods are described for determining threedimensional wind velocities in mountain waves using limited data from Sailplane flights. Results are presented for application of the methods to data from a flight in the Sierra N evada mountain wave.
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Estimating wind velocities from limited Sailplane flight data
Signal and Image Processing, 2011Co-Authors: Ni Zhang, Rick P. Millane, Einar Enevoldson, Alan J. Hunter, James E. MurrayAbstract:The problem of estimating wind velocities from limited flight data recordings is considered, with application to Sailplane flights in high-altitude mountain waves. Sailplane flight recorders routinely measure only GPS position and, infrequently, also airspeed and the problem is underdetermined. Maximum likelihood and maximum a posteriori estimators are developed for these kinds of data and tested by simulation and by application to Sailplane flight data.
Ni Zhang - One of the best experts on this subject based on the ideXlab platform.
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Analysis of mountain wave 3D wind fields in the Andes derived from high-altitude Sailplane flights
Technical Soaring, 2017Co-Authors: Rick P. Millane, Ni Zhang, Einar Enevoldson, James E. MurrayAbstract:Mountain lee waves are of importance in meteorology since they produce drag that affects the general circulation, and can influence windstorms, clear-air turbulence and ozone abundance. Since mountain waves are used routinely by Sailplane pilots, data collected during wave flights are potentially useful for studying the structure of mountain waves. We have previously described methods for determining 3D wind velocities in mountain waves from limited Sailplane flight data. These methods are applied to data from a high-altitude Sailplane flight in the lee of the Andes that reached an altitude of over 15,000 m, well into the stratosphere, allowing a unique kind of in-situ observation of stratospheric mountain waves. The derived wind fields show parts of the wave structure in the troposphere and the stratosphere, and are compared with other observational data. Thus, a minimally instrumented Sailplane can provide useful data for mountain wave research.
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Determining wind fields in atmospheric mountain waves using Sailplane flight data
Image Reconstruction from Incomplete Data VII, 2012Co-Authors: Ni Zhang, Rick P. Millane, Einar Enevoldson, James E. MurrayAbstract:The problem of estimating wind velocities from limited flight data recordings is considered, with application to Sailplane flights in high-altitude atmospheric mountain waves. Sailplane flight recorders routinely measure only GPS position and the problem is highly underdetermined. The nature of this problem is studied and a maximum a posteriori estimator is developed using prior information on the wind velocity and the Sailplane airspeed and heading. The method is tested by simulation and by application to Sailplane flight data.
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Measuring 3DWind Fields in MountainWaves Using Sailplane Flight Data
Technical Soaring, 2012Co-Authors: Ni Zhang, Rick P. Millane, Einar Enevoldson, James E. MurrayAbstract:Mountain lee waves are of considerable interest in meteorology and also are used routinely by Sailplane pilots as a source of lift for high-attitude and long-distance flights. Data collected during wave flights therefore are potentially useful for studying the structure of mountain waves. Novel methods are described for determining three-dimensional wind velocities in mountain waves using limited data from Sailplane flights. Results are presented for application of the methods to data from a flight in the Sierra Nevada mountain wave. Presented at the XXX OSTIV Congress, Szeged, Hungary, 28 July – 4 August 2010
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Estimating Wind Velocities in Atmospheric Mountain Waves Using Sailplane Flight Data
University of Canterbury. Electrical and Computer Engineering, 2012Co-Authors: Ni ZhangAbstract:Atmospheric mountain waves form in the lee of mountainous terrain under appropriate conditions of the vertical structure of wind speed and atmospheric stability. Trapped lee waves can extend hundreds of kilometers downwind from the mountain range, and they can extend tens of kilometers vertically into the stratosphere. Mountain waves are of importance in meteorology as they affect the general circulation of the atmosphere, can influence the vertical structure of wind speed and temperature fields, produce turbulence and downdrafts that can be an aviation hazard, and affect the vertical transport of aerosols and trace gasses, and ozone concentration. Sailplane pilots make extensive use of mountain lee waves as a source of energy with which to climb. There are many Sailplane wave flights conducted every year throughout the world and they frequently cover large distances and reach high altitudes. Modern Sailplanes frequently carry flight recorders that record their position at regular intervals during the flight. There is therefore potential to use this recorded data to determine the 3D wind velocity at positions on the Sailplane flight path. This would provide an additional source of information on mountain waves to supplement other measurement techniques that might be useful for studies on mountain waves. The recorded data are limited however, and determination of wind velocities is not straightforward. This thesis is concerned with the development and application of techniques to determine the vector wind field in atmospheric mountain waves using the limited flight data collected during Sailplane flights. A detailed study is made of the characteristics, uniqueness, and sensitivity to errors in the data, of the problem of estimating the wind velocities from limited flight data consisting of ground velocities, possibly supplemented by air speed or heading data. A heuristic algorithm is developed for estimating 3D wind velocities in mountain waves from ground velocity and air speed data, and the algorithm is applied to flight data collected during “Perlan Project” flights. The problem is then posed as a statistical estimation problem and maximum likelihood and maximum a posteriori estimators are developed for a variety of different kinds of flight data. These estimators are tested on simulated flight data and data from Perlan Project flights
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measuring 3d wind fields in mountain waves using Sailplane flight data
2012Co-Authors: Ni Zhang, Rick P. Millane, Einar Enevoldson, James E. MurrayAbstract:Mountain lee waves are of considerable interest in meteorology and also are used routinely by Sailplane pilots as a source of lift for high-attitude and long-distance fligh ts. Data collected during wave flights therefore are potentially useful for studying the structure of mountain waves. Novel methods are described for determining threedimensional wind velocities in mountain waves using limited data from Sailplane flights. Results are presented for application of the methods to data from a flight in the Sierra N evada mountain wave.
Rick P. Millane - One of the best experts on this subject based on the ideXlab platform.
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Analysis of mountain wave 3D wind fields in the Andes derived from high-altitude Sailplane flights
Technical Soaring, 2017Co-Authors: Rick P. Millane, Ni Zhang, Einar Enevoldson, James E. MurrayAbstract:Mountain lee waves are of importance in meteorology since they produce drag that affects the general circulation, and can influence windstorms, clear-air turbulence and ozone abundance. Since mountain waves are used routinely by Sailplane pilots, data collected during wave flights are potentially useful for studying the structure of mountain waves. We have previously described methods for determining 3D wind velocities in mountain waves from limited Sailplane flight data. These methods are applied to data from a high-altitude Sailplane flight in the lee of the Andes that reached an altitude of over 15,000 m, well into the stratosphere, allowing a unique kind of in-situ observation of stratospheric mountain waves. The derived wind fields show parts of the wave structure in the troposphere and the stratosphere, and are compared with other observational data. Thus, a minimally instrumented Sailplane can provide useful data for mountain wave research.
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Determining wind fields in atmospheric mountain waves using Sailplane flight data
Image Reconstruction from Incomplete Data VII, 2012Co-Authors: Ni Zhang, Rick P. Millane, Einar Enevoldson, James E. MurrayAbstract:The problem of estimating wind velocities from limited flight data recordings is considered, with application to Sailplane flights in high-altitude atmospheric mountain waves. Sailplane flight recorders routinely measure only GPS position and the problem is highly underdetermined. The nature of this problem is studied and a maximum a posteriori estimator is developed using prior information on the wind velocity and the Sailplane airspeed and heading. The method is tested by simulation and by application to Sailplane flight data.
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Measuring 3DWind Fields in MountainWaves Using Sailplane Flight Data
Technical Soaring, 2012Co-Authors: Ni Zhang, Rick P. Millane, Einar Enevoldson, James E. MurrayAbstract:Mountain lee waves are of considerable interest in meteorology and also are used routinely by Sailplane pilots as a source of lift for high-attitude and long-distance flights. Data collected during wave flights therefore are potentially useful for studying the structure of mountain waves. Novel methods are described for determining three-dimensional wind velocities in mountain waves using limited data from Sailplane flights. Results are presented for application of the methods to data from a flight in the Sierra Nevada mountain wave. Presented at the XXX OSTIV Congress, Szeged, Hungary, 28 July – 4 August 2010
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measuring 3d wind fields in mountain waves using Sailplane flight data
2012Co-Authors: Ni Zhang, Rick P. Millane, Einar Enevoldson, James E. MurrayAbstract:Mountain lee waves are of considerable interest in meteorology and also are used routinely by Sailplane pilots as a source of lift for high-attitude and long-distance fligh ts. Data collected during wave flights therefore are potentially useful for studying the structure of mountain waves. Novel methods are described for determining threedimensional wind velocities in mountain waves using limited data from Sailplane flights. Results are presented for application of the methods to data from a flight in the Sierra N evada mountain wave.
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Estimating wind velocities from limited Sailplane flight data
Signal and Image Processing, 2011Co-Authors: Ni Zhang, Rick P. Millane, Einar Enevoldson, Alan J. Hunter, James E. MurrayAbstract:The problem of estimating wind velocities from limited flight data recordings is considered, with application to Sailplane flights in high-altitude mountain waves. Sailplane flight recorders routinely measure only GPS position and, infrequently, also airspeed and the problem is underdetermined. Maximum likelihood and maximum a posteriori estimators are developed for these kinds of data and tested by simulation and by application to Sailplane flight data.
Einar Enevoldson - One of the best experts on this subject based on the ideXlab platform.
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Analysis of mountain wave 3D wind fields in the Andes derived from high-altitude Sailplane flights
Technical Soaring, 2017Co-Authors: Rick P. Millane, Ni Zhang, Einar Enevoldson, James E. MurrayAbstract:Mountain lee waves are of importance in meteorology since they produce drag that affects the general circulation, and can influence windstorms, clear-air turbulence and ozone abundance. Since mountain waves are used routinely by Sailplane pilots, data collected during wave flights are potentially useful for studying the structure of mountain waves. We have previously described methods for determining 3D wind velocities in mountain waves from limited Sailplane flight data. These methods are applied to data from a high-altitude Sailplane flight in the lee of the Andes that reached an altitude of over 15,000 m, well into the stratosphere, allowing a unique kind of in-situ observation of stratospheric mountain waves. The derived wind fields show parts of the wave structure in the troposphere and the stratosphere, and are compared with other observational data. Thus, a minimally instrumented Sailplane can provide useful data for mountain wave research.
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Determining wind fields in atmospheric mountain waves using Sailplane flight data
Image Reconstruction from Incomplete Data VII, 2012Co-Authors: Ni Zhang, Rick P. Millane, Einar Enevoldson, James E. MurrayAbstract:The problem of estimating wind velocities from limited flight data recordings is considered, with application to Sailplane flights in high-altitude atmospheric mountain waves. Sailplane flight recorders routinely measure only GPS position and the problem is highly underdetermined. The nature of this problem is studied and a maximum a posteriori estimator is developed using prior information on the wind velocity and the Sailplane airspeed and heading. The method is tested by simulation and by application to Sailplane flight data.
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Measuring 3DWind Fields in MountainWaves Using Sailplane Flight Data
Technical Soaring, 2012Co-Authors: Ni Zhang, Rick P. Millane, Einar Enevoldson, James E. MurrayAbstract:Mountain lee waves are of considerable interest in meteorology and also are used routinely by Sailplane pilots as a source of lift for high-attitude and long-distance flights. Data collected during wave flights therefore are potentially useful for studying the structure of mountain waves. Novel methods are described for determining three-dimensional wind velocities in mountain waves using limited data from Sailplane flights. Results are presented for application of the methods to data from a flight in the Sierra Nevada mountain wave. Presented at the XXX OSTIV Congress, Szeged, Hungary, 28 July – 4 August 2010
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measuring 3d wind fields in mountain waves using Sailplane flight data
2012Co-Authors: Ni Zhang, Rick P. Millane, Einar Enevoldson, James E. MurrayAbstract:Mountain lee waves are of considerable interest in meteorology and also are used routinely by Sailplane pilots as a source of lift for high-attitude and long-distance fligh ts. Data collected during wave flights therefore are potentially useful for studying the structure of mountain waves. Novel methods are described for determining threedimensional wind velocities in mountain waves using limited data from Sailplane flights. Results are presented for application of the methods to data from a flight in the Sierra N evada mountain wave.
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Estimating wind velocities from limited Sailplane flight data
Signal and Image Processing, 2011Co-Authors: Ni Zhang, Rick P. Millane, Einar Enevoldson, Alan J. Hunter, James E. MurrayAbstract:The problem of estimating wind velocities from limited flight data recordings is considered, with application to Sailplane flights in high-altitude mountain waves. Sailplane flight recorders routinely measure only GPS position and, infrequently, also airspeed and the problem is underdetermined. Maximum likelihood and maximum a posteriori estimators are developed for these kinds of data and tested by simulation and by application to Sailplane flight data.
Mark D. Maughmer - One of the best experts on this subject based on the ideXlab platform.
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THE DESIGN OF WINGLETS FOR HIGH-PERFORMANCE
2014Co-Authors: Mark D. MaughmerAbstract:Although theoretical tools for the design of winglets for high-performance Sailplanes were initially of limited value, simple methods were used to design winglets that gradually became accepted as benefiting overall Sailplane performance. To further these gains, an improved methodology for winglet design has been developed. This methodology incorporates a detailed component drag buildup that includes the ability to interpolate input airfoil drag and moment data across operational lift coefficient, Reynolds number, and flap-setting ranges. Induced drag is initially predicted using a relatively fast multi- lifting line method. In the final stages of the design process, a full panel method, including relaxed-wake modeling, is employed. The drag predictions are used to compute speed polars for both level and turning flight. The predicted performance is in good agreement with flight-test results. The straight and turning flight speed polars are then used to obtain cross-country performance over a range of thermal strengths, sizes, and shapes. Example design cases presented here demonstrate that winglets can provide a small, but important, performance advantage over much of the operating range for both span limited and span unlimited high-performance Sailplanes. Nomenclature b span c wing chord cl section lift coefficient h winglet height CDp profile drag coefficient averaged over span K induced drag factor S planform area V airspeed VCC average cross-country speed VCR crossover velocity VS sink rate W weight ρ air densit
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The Conceptual Design of a Tailless Sailplane Having a Stabilizing Fuselage
Technical Soaring, 2011Co-Authors: Ippei Otani, Mark D. MaughmerAbstract:A conceptual design of a tailless Standard Class Sailplane is presented in this paper. Longitudinal static stability requires a negative pitching moment gradient with respect to the lift coefficient and a positive pitching moment at zero lift. The former depends on the position of the center of gravity with respect to the neutral point of the aircraft, while the latter, in the case of tailless Sailplanes, is obtained by designing the wing to take over the stabilizing function normally provided by the empennage. The two methods employed to achieve this, often in combination, are the use of an airfoil with a positive moment coefficient about its aerodynamic center, and the aft sweeping with washout of the wing to provide the needed positive pitching moment at zero lift. The idea introduced here explores a fuselage design that helps to support the stabilizing function. The pressure distribution around the fuselage is tailored to contribute to the stability of the vehicle. To determine the overall benefit of this concept, the cross-country performance of the tailless aircraft is predicted and compared to that of a current conventional Sailplane. It is found that the conceptual design is predicted to achieve performance levels comparable to those of conventional designs.
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THE DESIGN OF WINGLETS FOR HIGH-PERFORMANCE SailplaneS
Journal of Aircraft, 2003Co-Authors: Mark D. MaughmerAbstract:Although theoretical tools for the design of winglets for high-performance Sailplanes were initially of limited value, simple methods were used to design winglets that gradually became accepted as benefiting overall Sailplane performance. To further these gains, an improved methodology for winglet design has been developed. This methodology incorporates a detailed component drag buildup that includes the ability to interpolate input airfoil drag and moment data across operational lift coefficient, Reynolds number, and flapsetting ranges. Induced drag is initially predicted using a relatively fast multi- lifting line method. In the final stages of the design process, a full panel method, including relaxed-wake modeling, is employed. The drag predictions are used to compute speed polars for both level and turning flight. The predicted performance is in good agreement with flight-test results. The straight and turning flight speed polars are then used to obtain cross-country performance over a range of thermal strengths, sizes, and shapes. Example design cases presented here demonstrate that winglets can provide a small, but important, performance advantage over much of the operating range for both span limited and span unlimited high-performance Sailplanes.
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THE DESIGN OF WINGLETS FOR HIGH-PERFORMANCE SailplaneS
Technical Soaring, 2003Co-Authors: Mark D. MaughmerAbstract:Although theoretical tools for the design of winglets for high-performance Sailplanes were initially of limited value, simple methods were used to design winglets that gradually became accepted as benefiting overall Sailplane performance. As understanding was gained, improved methods for winglet design were developed. The current approach incorporates a detailed component drag buildup that interpolates airfoil drag and moment data across operational lift-coefficient, Reynolds-numbe{, and flap-deflection ranges. Induced drag is initially predicted using a relatively fast multiple lifting-line method. In the final stages of the design process, a full panel method, including relaxed-wake modeling, is employed. The drag predictions are used to compute speed polars for both level and turning flight. The predicted performance is in good agreement with flight-test results. The straight- and turningflight-speed polars are then used to obtain average crosscountry speeds as they depend on thermal strength, size, and shape, which are used to design the winglets that provide the greatest gain in overall performance. Flight-test measurements and competition results have demonstrated that the design methods produce winglets that provide an important performance advantage over much of the operating range for both span-limited and span-unlimited highperformance Sailplanes.
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The Penn State Sailplane Course
2002Co-Authors: Götz Bramesfeld, Mark D. MaughmerAbstract:Since 1989, the Department of Aerospace Engineering of The Pennsylvania State University has offered a special undergraduate project course that has a strong emphasis on “hands on” design and fabrication. Specifically, a group of approximately twenty-five students, freshmen through seniors, is involved in the design and construction of high-performance Sailplanes. Students can and are expected to enroll in this course for every semester during their undergraduate study. The basic course structure consists primarily of three components. The first, lecture, provides the student with the necessary theoretical background of modern Sailplanes and their design requirements. The second component is concerned with design groups of four to six students, in which the students design and analyze Sailplanes, such as their performance, structure, stability and control, and so forth. The third component is the fabrication of parts that have been designed and analyzed theoretically, such as the current project of a full-size, 50-foot wingspan Sailplane made out of modern composite materials. To a large part, the learning experience can be related to the integrated nature of the design course, as well as to the interaction of undergraduate students at all levels of their program.
