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  • Aircraft Propulsion and Power  (10)
  • Acoustics  (9)
  • Astrodynamics
  • 2010-2014  (12)
  • 2000-2004  (13)
  • 1960-1964
  • 1
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    A Direct Approach for Minimum Fuel Maneuvers of Distributed Spacecraft in Multiple Flight Regimes (2004)
    In:  CASI
    Details
    Publication Date: 2018-06-06
    Description: In this work we present a method to solve the impulsive minimum fuel maneuver problem for a distributed set of spacecraft. We develop the method assuming a fully non-linear dynamics model and parameterize the problem to allow the method to be applicable to any flight regime. Furthermore, the approach is not limited by the inter-spacecraft separation distances and is applicable to both small formations as well as constellations. We assume that the desired relative motion is driven by mission requirements and has been determined a-priori. The goal of this work is to develop a technique to achieve the desired relative motion in a minimum fuel manner. To permit applicability to multiple flight regimes, we have chosen to parameterize the cost function in terms of the maneuver times expressed in a useful time system and the maneuver locations expressed in their Cartesian vector representations. We also include as an independent variable the initial reference orbit to solve for the optimal injection orbit to minimize and equalize the fuel expenditure of distributed sets of spacecraft with large inter-spacecraft separations. In this work we derive the derivatives of the cost and constraints with respect to all of the independent variables.
    Keywords: Astrodynamics
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 2
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    Turbofan Noise Studied in Unique Model Research Program in NASA Glenn's 9- by 15-Foot Low-Speed Wind Tunnel (2001)
    In:  CASI
    Details
    Publication Date: 2018-06-02
    Description: A comprehensive aeroacoustic research program called the Source Diagnostic Test was recently concluded in NASA Glenn Research Center's 9- by 15-Foot Low Speed Wind Tunnel. The testing involved representatives from Glenn, NASA Langley Research Center, GE Aircraft Engines, and the Boeing Company. The technical objectives of this research were to identify the different source mechanisms of noise in a modern, high-bypass turbofan aircraft engine through scale-model testing and to make detailed acoustic and aerodynamic measurements to more fully understand the physics of how turbofan noise is generated.
    Keywords: Acoustics
    Type: Research and Technology 2000; NASA/TM-2001-210605
    Format: application/pdf
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  • 3
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    Vibration Test Demonstrated Dynamic Capability of an Operating Stirling Convertor (2001)
    In:  CASI
    Details
    Publication Date: 2018-06-05
    Description: The NASA Glenn Research Center and the U.S. Department of Energy are currently developing a high-efficiency, long-life, free piston Stirling convertor for use as an advanced spacecraft power system for future NASA missions. As part of this development, a Stirling Technology Demonstrator Converter (TDC), developed by Stirling Technology Company for the Department of Energy, was vibration tested at Glenn's Structural Dynamics Laboratory in November and December 1999. This testing demonstrated that the Stirling TDC is able to withstand the harsh random vibration (20 to 2000 Hz) seen during a typical spacecraft launch and to survive with no structural damage or functional power performance degradation, thereby enabling its use in future spacecraft power systems. Glenn and Stirling personnel conducted tests on a single 55 We TDC. The purpose was to characterize the TDC's structural response to vibration and to determine if the TDC could survive the vibration criteria established by the Jet Propulsion Laboratory for launch environments. The TDC was operated at full-stroke and full power conditions during the vibration testing.
    Keywords: Aircraft Propulsion and Power
    Type: Research and Technology 2000; NASA/TM-2001-210605
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  • 4
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    Optimal Orbit Design for the Magnetospheric Imaging Constellation (2001)
    In:  Other Sources
    Details
    Publication Date: 2019-07-17
    Description: The Magnetospheric Imaging Constellation (MagIC) is a NASA space science concept to study the Earth's Magnetosphere. The concept proposes to apply tomography techniques using an array of spacecraft to obtain three dimensional images of the Earth's magnetosphere. This paper presents an optimal orbit design to ensure that the constellation is in the desired region of the magnetosphere for maximum time. The solution is found using a steepest descent optimization algorithm that takes into account perturbations from the non-spherical Earth, drag, Sun, Moon and other significant bodies. The solution also satisfies constraints on maximum eclipse duration and geometry constraints to allow an adequate GPS navigation solution. We present three solutions depending upon the epoch of the primary science: vernal equinox, summer solstice, and a third midway between the vernal equinox and summer solstice. Orbit insertion is also considered. All spacecraft are assumed to be launched on a single vehicle into a nominal orbit and the (Delta)V's to achieve the nominal orbit are presented. After insertion into the nominal orbit, each spacecraft undergoes a phasing maneuver to place it in the appropriate position with respect to the rest of the constellation. We present a minimum fuel approach to maneuver each spacecraft from the nominal orbit into the desired final orbit.
    Keywords: Astrodynamics
    Type: 16th International Symposium on Space Flight Dynamics; Pasadena, CA; United States
    Format: text
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  • 5
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    A Preliminary Formation Flying Orbit Dynamics Analysis for Leonardo-BRDF (2001)
    In:  Other Sources
    Details
    Publication Date: 2019-07-17
    Description: Leonardo-BRDF is a NASA mission concept proposed to allow the investigation of radiative transfer and its effect on the Earth's climate and atmospheric phenomenon. Enabled by the recent developments in small-satellite and formation flying technology, the mission is envisioned to be composed of an array of spacecraft in carefully designed orbits. The different perspectives provided by a distributed array of spacecraft offer a unique advantage to study the Earth's albedo. This paper presents the orbit dynamics analysis performed in the context of the Leonardo-BRDF science requirements. First, the albedo integral is investigated and the effect of viewing geometry on science return is studied. The method used in this paper, based on Gauss quadrature, provides the optimal formation geometry to ensure that the value of the integral is accurately approximated. An orbit design approach is presented to achieve specific relative orbit geometries while simultaneously satisfying orbit dynamics constraints to reduce formation-keeping fuel expenditure. The relative geometry afforded by the design is discussed in terms of mission requirements. An optimal two-burn initialization scheme is presented with the required delta-V to distribute all spacecraft from a common parking orbit into their appropriate orbits in the formation. Finally, formation-keeping strategies are developed and the associated delta-V's are calculated to maintain the formation in the presence of perturbations.
    Keywords: Astrodynamics
    Type: 2001 Flight Mechanics Symposium; 131; NASA/CP-2001-209986
    Format: text
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  • 6
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    Investigation of Acoustic Fields for the Cassini Spacecraft: Reverberant Versus Launch Environments (2000)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The characterization and understanding of the acoustic field within a launch vehicle's payload fairing (PLF) is critical to the qualification of a spacecraft and ultimately to the success of its mission. Acoustic measurements taken recently for the Cassini mission have allowed unique opportunities to advance the aerospace industry's knowledge in this field. Prior to its launch, the expected liftoff acoustic environment of the spacecraft was investigated in a full-scale acoustic test of a Titan IV PLF and Cassini simulator in a reverberant test chamber. A major goal of this acoustic ground test was to quantify and verify the noise reduction performance of special barrier blankets that were designed especially to reduce the Cassirii acoustic environment. This paper will describe both the ground test and flight measurements, and compare the Cassini acoustic environment measured during launch with that measured earlier in the ground test. Special emphasis will be given to the noise reduction performance of the barrier blankets and to the acoustic coherence measured within the PLF.
    Keywords: Acoustics
    Type: NASA/TM-2000-209387 , E-11814 , AIAA Paper 99-1985 , NAS 1.15:209387 , Aerocoustics; May 10, 1999 - May 12, 1999; Bellevue, WA; United States
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  • 7
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    The Testing Behind The Test Facility: The Acoustic Design of the NASA Glenn Research Center's World-Class Reverberant Acoustic Test Facility (2011)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The National Aeronautics and Space Administration (NASA) Glenn Research Center (GRC) is leading the design and build of the new world-class vibroacoustic test capabilities at the NASA GRC?s Plum Brook Station in Sandusky, Ohio, USA. Benham Companies, LLC is currently constructing modal, base-shake sine and reverberant acoustic test facilities to support the future testing needs of NASA?s space exploration program. T he large Reverberant Acoustic Test Facility (RATF) will be approximately 101,000 ft3 in volume and capable of achieving an empty chamber acoustic overall sound pressure level (OASPL) of 163 dB. This combination of size and acoustic power is unprecedented amongst the world?s known active reverberant acoustic test facilities. The key to achieving the expected acoustic test spectra for a range of many NASA space flight environments in the RATF is the knowledge gained from a series of ground acoustic tests. Data was obtained from several NASA-sponsored test programs, including testing performed at the National Research Council of Canada?s acoustic test facility in Ottawa, Ontario, Canada, and at the Redstone Technical Test Center acoustic test facility in Huntsville, Alabama, USA. The majority of these tests were performed to characterize the acoustic performance of the modulators (noise generators) and representative horns that would be required to meet the desired spectra, as well as to evaluate possible supplemental gas jet noise sources. The knowledge obtained in each of these test programs enabled the design of the RATF sound generation system to confidently advance to its final acoustic de-sign and subsequent on-going construction.
    Keywords: Acoustics
    Type: E-17701 , IMAC XXIX, Jan.31- Feb.3, 2011; Jan 31, 2011 - Feb 03, 2011; Cleveland, OH; United States
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  • 8
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    Overview of ERA Ultra High Bypass Propulsor Technology Development (2011)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A review of the current research being conducted under the Environmentally Responsible Aviation (ERA) Ultra High Bypass (UHB) Testing subelement is presented. The four exiting tasks under the subelement, a description of each task, and the current status of each are given. The four tasks are: 1. Collaborate with P&W to design, fabricate and test a second generation of Geared Turbofan 2. Design, fabricate and test advanced Over the Rotor acoustic treatment and acoustically treated Soft Vanes 3. Develop a Shape Memory Alloy Variable Area Nozzle concept and demonstrate prototype 4. Refurbish and update the GRC Ultra High Bypass Drive Rig Following the current task updates, an overview of three proposed additional tasks to support the existing tasks is presented. The additional tasks would allow noise reduction and noise diagnostic testing technologies to be demonstrated at TRL 4 as part of existing planned fan model testing in the NASA Glenn 9 x15 Low Speed Wind Tunnel under the ERA UHB Testing subelement.
    Keywords: Aircraft Propulsion and Power
    Type: E-17844 , Acoustics Technical Working Group Meeting; Apr 21, 2011 - Apr 22, 2011; Cleveland, OH; United States
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  • 9
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    The Development of the Acoustic Design of NASA Glenn Research Center's New Reverberant Acoustic Test Facility (2011)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The National Aeronautics and Space Administration (NASA) Glenn Research Center (GRC) is leading the design and build of the new world-class vibroacoustic test capabilities at the NASA GRC's Plum Brook Station in Sandusky, Ohio, USA. Benham Companies, LLC is currently constructing modal, base-shake sine and reverberant acoustic test facilities to support the future testing needs of NASA s space exploration program. The large Reverberant Acoustic Test Facility (RATF) will be approximately 101,000 ft3 in volume and capable of achieving an empty chamber acoustic overall sound pressure level (OASPL) of 163 dB. This combination of size and acoustic power is unprecedented amongst the world s known active reverberant acoustic test facilities. The key to achieving the expected acoustic test spectra for a range of many NASA space flight environments in the RATF is the knowledge gained from a series of ground acoustic tests. Data was obtained from several NASA-sponsored test programs, including testing performed at the National Research Council of Canada s acoustic test facility in Ottawa, Ontario, Canada, and at the Redstone Technical Test Center acoustic test facility in Huntsville, Alabama, USA. The majority of these tests were performed to characterize the acoustic performance of the modulators (noise generators) and representative horns that would be required to meet the desired spectra, as well as to evaluate possible supplemental gas jet noise sources. The knowledge obtained in each of these test programs enabled the design of the RATF sound generation system to confidently advance to its final acoustic design and subsequent on-going construction.
    Keywords: Acoustics
    Type: E-17660-1 , Aerospace Testing Seminar; Mar 29, 2011 - Mar 31, 2011; Los Angeles, CA; United States
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  • 10
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    The Testing Behind The Test Facility: The Acoustic Design of the NASA Glenn Research Center's World-Class Reverberant Acoustic Test Facility (2011)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The National Aeronautics and Space Administration (NASA) Glenn Research Center (GRC) is leading the design and build of the new world-class vibroacoustic test capabilities at the NASA GRC's Plum Brook Station in Sandusky, Ohio, USA. Benham Companies, LLC is currently constructing modal, base-shake sine and reverberant acoustic test facilities to support the future testing needs of NASA's space exploration program. The large Reverberant Acoustic Test Facility (RATF) will be approximately 101,000 cu ft in volume and capable of achieving an empty chamber acoustic overall sound pressure level (OASPL) of 163 dB. This combination of size and acoustic power is unprecedented amongst the world's known active reverberant acoustic test facilities. The key to achieving the expected acoustic test spectra for a range of many NASA space flight environments in the RATF is the knowledge gained from a series of ground acoustic tests. Data was obtained from several NASA-sponsored test programs, including testing performed at the National Research Council of Canada's acoustic test facility in Ottawa, Ontario, Canada, and at the Redstone Technical Test Center acoustic test facility in Huntsville, Alabama, USA. The majority of these tests were performed to characterize the acoustic performance of the modulators (noise generators) and representative horns that would be required to meet the desired spectra, as well as to evaluate possible supplemental gas jet noise sources. The knowledge obtained in each of these test programs enabled the design of the RATF sound generation system to confidently advance to its final acoustic design and subsequent on-going construction.
    Keywords: Acoustics
    Type: E-17433-1 , 29th International Modal Analysis Conference (IMAC); Jan 31, 2011 - Feb 03, 2011; Jacksonville, FL; United States
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