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  • 1
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    Ground-to-air flow visualization using Solar Calcium-K line Background-Oriented Schlieren (2016)
    Springer
    Details
    Publication Date: 2016-12-15
    Print ISSN: 0723-4864
    Electronic ISSN: 1432-1114
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Springer
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    PAPER CURRENT
  • 2
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    Imaging Shockwaves and Vortices on Full-Scale Aircraft Using Schlieren Photography with the Sun's Limb from the Ground and from an Aircraft (2016)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Advancing the state of the art of schlieren photography for validation of wind tunnel and CFD efforts; may lead to better low boom commercial aircraft.
    Keywords: Solar Physics; Fluid Mechanics and Thermodynamics
    Type: DFRC-E-DAA-TN32671 , Industry Panel Presentation at the University of Southern California; Nov 03, 2017; Los Angeles, CA; United States|International Symposium on Flow Visualization; Jun 19, 2016 - Jun 22, 2016; Gatlinburg, TN; United States
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 3
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    SCAMP: Rapid Focused Sonic Boom Waypoint Flight Planning Methods, Execution, and Results (2012)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: 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.
    Keywords: Acoustics
    Type: DFRC-E-DAA-TN6916 , AIAA Aerospace Sciences Meeting; Dec 19, 2012 - Dec 21, 2012; Grapevine, TX; United States|Industry Panel Presentation at the University of Southern California; Nov 03, 2017; Los Angeles, CA; United States
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 4
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    The Effect of Sonic Booms on Earthquake Warning Systems (2011)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Several aerospace companies are designing quiet supersonic business jets for service over the United States. These aircraft have the potential to increase the occurrence of mild sonic booms across the country. This leads to interest among earthquake warning (EQW) developers and the general seismological community in characterizing the effect of sonic booms on seismic sensors in the field, their potential impact on EQW systems, and means of discriminating their signatures from those of earthquakes. The SonicBREWS project (Sonic Boom Resistant Earthquake Warning Systems) is a collaborative effort between Seismic Warning Systems, Inc. (SWS) and NASA Dryden Flight Research Center. This project aims to evaluate the effects of sonic booms on EQW sensors. The study consists of exposing high-sample-rate (1000 sps) triaxial accelerometers to sonic booms with overpressures ranging from 10 to 600 Pa in the free field and the built environment. The accelerometers record the coupling of the sonic boom to the ground and surrounding structures, while microphones record the acoustic wave above ground near the sensor. Sonic booms are broadband signals with more high-frequency content than earthquakes. Even a 1000 sps accelerometer will produce a significantly aliased record. Thus the observed peak ground velocity is strongly dependent on the sampling rate, and increases as the sampling rate is reduced. At 1000 sps we observe ground velocities that exceed those of P-waves from M〈sub〉L 〈/sub〉 3 earthquakes at local distances, suggesting that sonic booms are not negligible for EQW applications. We present the results of several experiments conducted under SonicBREWS showing the effects of typical-case low amplitude sonic booms and worst-case high amplitude booms. We show the effects of various sensor placements and sensor array geometries. Finally, we suggest possible avenues for discriminating sonic booms from earthquakes for the purposes of EQW.
    Keywords: Geosciences (General)
    Type: DFRC-E-DAA-TN3366 , Seismological Society of America''s Annual Meeting; Apr 13, 2011; Memphis, TX; United States
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 5
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    High-Quality Seismic Observations of Sonic Booms (2011)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The SonicBREWS project (Sonic Boom Resistant Earthquake Warning Systems) is a collaborative effort between Seismic Warning Systems, Inc. and NASA Dryden Flight Research Center. This project aims to evaluate the effects of sonic booms on Earthquake Warning Systems in order to prevent such systems from experiencing false alarms due to sonic booms. The airspace above the Antelope Valley, California includes the High Altitude Supersonic Corridor and the Black Mountain Supersonic Corridor. These corridors are among the few places in the US where supersonic flight is permitted, and sonic booms are commonplace in the Antelope Valley. One result of this project is a rich dataset of high-quality accelerometer records of sonic booms which can shed light on the interaction between these atmospheric phenomena and the solid earth. Nearly 100 sonic booms were recorded with low-noise triaxial MEMS accelerometers recording 1000 samples per second. The sonic booms had peak overpressures ranging up to approximately 10 psf and were recorded in three flight series in 2010 and 2011. Each boom was recorded with up to four accelerometers in various array configurations up to 100 meter baseline lengths, both in the built environment and the free field. All sonic booms were also recorded by nearby microphones. We present the results of the project in terms of the potential for sonic-boom-induced false alarms in Earthquake Warning Systems, and highlight some of the interesting features of the dataset.
    Keywords: Geosciences (General)
    Type: DFRC-372 , S31D-2272 , DFRC-E-DAA-TN4480 , AGU Fall Meeting 2011; Dec 05, 2011 - Dec 09, 2011; San Francisco, CA; United States
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 6
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    Quiet Sonic Booms: A NASA and Industry Progress Report (2011)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: The purpose of this Oral Presentation is to present a progress report on NASA and Industry efforts related to Quiet Sonic Boom Program activities. This presentation will review changes in aircraft shaping to produce quiet supersonic booms and associated supersonic flight test methods and results. In addition, new flight test profiles have been recently developed that have allowed for the generation of sonic booms of varying intensity. These new flight test profiles have allowed for ground testing of the response of various building structures to sonic booms and the associated public acceptability to various sonic boom intensities. The new flight test profiles and associated ground measurement test methods will be reviewed. Finally, this Oral Presentation will review the International Regulatory requirements that would be involved to change aviation regulation and allow for overland quiet supersonic flight.
    Keywords: Acoustics
    Type: DFRC-E-DAA-TN3217 , 43rd European Symposium of the Society of Experimental; May 25, 2011; Venice; Italy
    Format: text
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    NASA TECHNICAL REPORTS
  • 7
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    Background Oriented Schlieren (BOS) of a Supersonic Aircraft In Flight (2016)
    In:  CASI
    Details
    Publication Date: 2019-07-20
    Description: This article describes the development and use of Background Oriented Schlieren on a full-scale supersonic jet in flight. A series of flight tests was performed in October, 2014 and February 2015 using the flora of the desert floor in the Supersonic Flight Corridor on the Edwards Air Force Base as a background. Flight planning was designed based on the camera resolution, the mean size and color of the predominant plants, and the navigation and coordination of two aircraft. Software used to process the image data was improved with additional utilities. The planning proved to be effective and the vast majority of the passes of the target aircraft were successfully recorded. Results were obtained that are the most detailed schlieren imagery of an aircraft in flight to date.
    Keywords: Aerodynamics; Instrumentation and Photography
    Type: ARC-E-DAA-TN32179 , AIAA Aviation Forum; Jun 13, 2016 - Jun 17, 2016; Washington, DC; United States
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 8
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    An Overview of Lessons Learned from Sonic-Boom Flight Research Projects Conducted by NASA Armstrong Flight Research Center (2018)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: This presentation describes the planning and executing of large scale sonic-boom acoustics tests as a part of LBFD testing with the goal to give the future teams the road-map for how to efficiently and effectively plan and execute these types of tests.
    Keywords: Acoustics
    Type: AFRC-E-DAA-TN58337 , AIAA Aviation Forum; Jun 25, 2018 - Jun 29, 2018; Atlanta, GA; United States
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 9
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    An Overview of Lessons Learned from Sonic-boom Flight Research Projects Conducted by NASA Armstrong Flight Research Center (2018)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Over the course of four years, a team of aerospace engineers at the National Aeronautics and Space Administration Armstrong Flight Research Center completed four projects, each with the objective to research sonic-boom signatures from a ground-and building-level perspective. The relatively compressed timeline of these projects resulted in many lessons learned. With each successive project, these lessons have been more relied upon and referenced. This paper provides a high-level overview of the teams relevant lessons learned and the importance of these lessons for future projects.
    Keywords: Aeronautics (General)
    Type: AFRC-E-DAA-TN56431 , AIAA Aviation and Aeronautics Forum and Exposition (AVIATION 2018); Jun 25, 2018 - Jun 29, 2018; Atlanta, GA; United States
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 10
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    Human Response to Low-Intensity Sonic Booms Heard Indoors and Outdoors (2010)
    In:  CASI
    Details
    Publication Date: 2019-07-12
    Description: Test subjects seated inside and outside a house were exposed to low-intensity N-wave sonic booms during a 3-week test period in June 2006- The house was instrumented to measure the booms both inside and out. F-18 aircraft were flown to achieve a variety of boom overpressures from approximately .1 to .6 psf During four test days, seventy-seven test subjects heard the booms while seated inside and outside the house. Using the Magnitude Estimation methodology and artificial reference sounds ; the subjects rated the annoyance of the booms. Since the same subjects heard similar booms both inside and outside the house, comparative ratings of indoor and outdoor annoyance were obtained. For a given metric level, indoor subjects gave higher annoyance scores than outdoor subjects. For a given boom; annoyance scores inside were on average the same as those outside. In a post-test questionnaire, the majority of subjects rated the indoor booms as more annoying than the outdoor ones. These results are discussed in this paper.
    Keywords: Acoustics
    Type: NASA/TM-2010-216685 , L-19846 , NF1676L-10465
    Format: application/pdf
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    NASA TECHNICAL REPORTS
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