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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
NASA NTRSDate not supplied

Multidisciplinary Dynamic Testing Challenges in Validating the NASA Artemis Architecture

NASA is in the midst of bold and exciting next steps in human exploration and spaceflight. The designs of the new Space Launch System (SLS), the Orion spacecraft and the Exploration Ground Systems (EGS) for vehicle processing and launch are essentially complete and there has been significant progress in manufacturing and assembly of specific hardware for the Artemis I and Artemis II missions. Equally as important, the program level and integrated system level testing and analyses are also well underway to support integrated verification, validation, and certificate of flight readiness (CoFR) for the first Artemis mission. Testing and analysis are key to addressing technical challenges that the Artemis missions offer. Building block approaches are required that provide the right balance between component, system, and/or element level testing that satisfies verification and validation objectives and where, uncertainties are quantified and minimized. Artemis I is a system of systems that requires a fusion of test and analysis that adeptly characterizes critical interfaces between major program elements. NASA is implementing new in-situ testing that fuse traditional aerospace structures with civil structures, such as the Integrated Modal Test for the Artemis I vehicle where the Mobile Launcher and Crawler Transporter serve as a support structure whose dynamics couple with that of the Artemis I vehicle. This new paradigm requires a closer inspection of structural behavior of the Crawler Transporter and the Mobile Launcher as they now serve multiple purposes. This requires a paradigm shift to look beyond experimental modal techniques and incorporates operational modal analysis techniques to validate dynamic models from data collected during rollout to the launch pad. A further complicating factor is the Crawler Transporter generated ground forces have numerous harmonics making extracting dynamic responses of the Artemis I, Mobile Launcher, and Crawler Transporter coupled system challenging. This discussion explores all these challenges with and attempts to understand how we best build confidence in systems and system-of-systems performance capabilities and margins and understand uncertainties.

Joel W Sills↗
NASA NTRS2004

Evaluation and Analysis of F-16XL Wind Tunnel Data From Static and Dynamic Tests

A series of wind tunnel tests were conducted in the NASA Langley Research Center as part of an ongoing effort to develop and test mathematical models for aircraft rigid-body aerodynamics in nonlinear unsteady flight regimes. Analysis of measurement accuracy, especially for nonlinear dynamic systems that may exhibit complicated behaviors, is an essential component of this ongoing effort. In this report, tools for harmonic analysis of dynamic data and assessing measurement accuracy are presented. A linear aerodynamic model is assumed that is appropriate for conventional forced-oscillation experiments, although more general models can be used with these tools. Application of the tools to experimental data is demonstrated and results indicate the levels of uncertainty in output measurements that can arise from experimental setup, calibration procedures, mechanical limitations, and input errors.

Kim, Sungwan↗
NASA NTRS2003

Evaluation and Analysis of F-16XL Wind Tunnel Data from Dynamic Tests

A series of wind tunnel tests were conducted in the NASA Langley Research Center as part of an ongoing effort to develop and test mathematical models for aircraft rigid-body aerodynamics in nonlinear unsteady flight regimes. Analysis of measurement accuracy, especially for nonlinear dynamic systems that may exhibit complicated behaviors, is an essential component of this ongoing effort. In this paper, tools for harmonic analysis of dynamic data and assessing measurement accuracy are presented. A linear aerodynamic model is assumed that is appropriate for conventional forced-oscillation experiments, although more general models can be used with these tools. Application of the tools to experimental data is demonstrated and results indicate the levels of uncertainty in output measurements that can arise from experimental setup, calibration procedures, mechanical limitations, and input errors.

Kim, Sungwan↗
NASA NTRS1974

Identification of structural parameters from helicopter dynamic test data

A method is presented for obtaining the mass, stiffness, and damping parameters of a linear mathematical model, having fewer degrees of freedom than the structure it represents, directly from dynamic response measurements on the actual helicopter without a priori knowledge of the physical characteristics of the fuselage. The only input information required in the formulation is the approximate natural frequency of each mode and mobility data measured proximate to these frequencies with sinusoidal force excitation applied at only one point on the vehicle. The practicality and numerical soundness of the theoretical development was demonstrated through a computer simulation of an experimental program.

Giansante, N.↗
NASA NTRS1988

An assessment of ground effects determined by static and dynamic testing techniques

A new testing technique was developed wherein the rate of descent can be included as a parameter in ground effects investigations. This technique simulates the rate of descent by horizontal motion of a model over an inclined ground board in the Langley Vortex Research Facility (VRF) During initial evaluations of the technique, dynamic ground effects data were obtained over the inclined ground board, steady state ground effects data were obtained over a flat portion of the ground board, and the results were compared to conventional static wind tunnel ground effect data both with and without a moving belt ground plane simulation. Initial testing and analysis led to the following conclusions: the moving belt ground plane had little effect on static ground effects for the configurations tested unless thrust reversers were employed; in general, rate-of-descent reduced ground effects to the point that for reversed thrust cases an expected loss of lift due to ground effects was eliminated at approach conditions; and, in general, the steady state results from the VRF matched static results obtained from the wind tunnel once the flow field stabilized over the flat portion of the ground board.

Paulson, John W., Jr.↗
NASA NTRS2013

Structural Dynamics Testing of Advanced Stirling Convertor Components

NASA Glenn Research Center has been supporting the development of Stirling energy conversion for use in space. Lockheed Martin has been contracted by the Department of Energy to design and fabricate flight-unit Advanced Stirling Radioisotope Generators, which utilize Sunpower, Inc., free-piston Advanced Stirling Convertors. The engineering unit generator has demonstrated conversion efficiency in excess of 20 percent, offering a significant improvement over existing radioisotope-fueled power systems. NASA Glenn has been supporting the development of this generator by developing the convertors through a technology development contract with Sunpower, and conducting research and experiments in a multitude of areas, such as high-temperature material properties, organics testing, and convertor-level extended operation. Since the generator must undergo launch, several launch simulation tests have also been performed at the convertor level. The standard test sequence for launch vibration exposure has consisted of workmanship and flight acceptance levels. Together, these exposures simulate what a flight convertor will experience. Recently, two supplementary tests were added to the launch vibration simulation activity. First was a vibration durability test of the convertor, intended to quantify the effect of vibration levels up to qualification level in both the lateral and axial directions. Second was qualification-level vibration of several heater heads with small oxide inclusions in the material. The goal of this test was to ascertain the effect of the inclusions on launch survivability to determine if the heater heads were suitable for flight.

Heaters↗
NASA NTRS1968

Environmental and dynamic testing

Low frequency plane wave sound generator and impedance measuring device applicable in environmental qualification testing of spacecraft and subsystems

Source record↗
NASA NTRS1970

Sinusoidal-pressure generator for testing dynamic pressure probes

Generator can produce sinusoidal pressures at frequencies from 300 to 5000 Hz and peak-to-peak amplitudes up to 5.6 lbs/sq in. Amplitude and phase-angle measurements made at various frequencies are compared with measurements from a piezoelectric transducer mounted flush with the resonant tube wall.

Englund, R., Jr.↗
NASA NTRS1972

Inflight dynamics testing of the Apollo spacecraft

Response of the Apollo command module, service and lunar module airframe while in a docked configuration in the flight environment was measured in a frequency band encompassing the first two bending modes. Transfer characteristics from thrust-application point to control-system sensor were examined. The frequency and the stability margins of the first two predominant structural resonances were verified by the test. This report describes the flight test that was performed and the postflight data analysis.

Peters, W. H.↗
NASA NTRS1971

Dynamic testing of a single-degree-of-freedom strapdown gyroscope

Test methods and results are presented for the equivalent average input rate of a single-degree-of-freedom gyroscope operated both open loop and with a ternary-logic pulse-torque-to-balance loop during multiaxis angular oscillation. For the open-loop tests, good agreement was obtained with theoretical results. Two-axis testing was performed for oscillations about the Input-Output axes, the Input-Spin axes, and the Spin-Output axes. These tests run in the torque-to-balance mode revealed significant departures from open-loop results in the induced drift rate. An analysis is developed explaining much of the closed-loop data presented. Test data for the gryoscope in a ternary torque-to-balance loop with constant input rates is presented. The tests demonstrate that the instrument rate linearity does not change with interrogation frequency from 3,600 to 14,400 Hz if the torque coil is tuned to offer a resistive load to the current switch. Analysis cited shows that gyroscope lag compensation eliminates multiple pulsing and other equivalent forms of degraded resolution in a wide variety of quantizing loops. This result is test verified for the ternary delta-modulator loop.

Lory, C. B.↗
NASA NTRS1972

Structural evaluations and dynamic testing of solar electric propulsion components.

Results of an experimental and analytical study of selected Solar Electric Propulsion (SEP) thrust subsystem components are presented. A mass and center-of-mass mockup of an experimental power conditioning (PC) panel was used for the PC structure evaluation. Test environment was based on that specified for prooftesting the Viking spacecraft electronics. Modal frequencies were surveyed over the range of 0-2000 Hz using both conventional test equipment and the holographic interferometry technique. Results of the forced vibration tests point to the need for some additional stiffening to make the structure qualifiable.

Womack, J. R.↗
NASA NTRS1973

Dynamic testing of complex structures

Response of structure is determined under impulses large enough to create severe strains. Electrodynamic shaker can provide impulses to nearly any point on structure and can deliver repeated pulses of varying force and duration.

Birs, C.↗
NASA NTRS1974

Fluid dynamics test method

Test method and apparatus determine fluid effective mass and damping in frequency range where effective mass may be considered as total mass less sum of slosh masses. Apparatus is designed so test tank and its mounting yoke are supported from structural test wall by series of flexures.

Gayman, W. H.↗