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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 649 records · Page 36

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NASA NTRS1976

Experimental investigation of a double-diffused MOS structure

Self-aligned polysilicon gate technology was applied to double-diffused MOS (DMOS) construction in a manner that retains processing simplicity and effectively eliminates parasitic overlap capacitance because of the self-aligning feature. Depletion mode load devices with the same dimensions as the DMOS transistors were integrated. The ratioless feature results in smaller dimension load devices, allowing for higher density integration with no increase in the processing complexity of standard MOS technology. A number of inverters connected as ring oscillators were used as a vehicle to test the performance and to verify the anticipated benefits. The propagation time-power dissipation product and process related parameters were measured and evaluated. This report includes (1) details of the process; (2) test data and design details for the DMOS transistor, the load device, the inverter, the ring oscillator, and a shift register with a novel tapered geometry for the output stages; and (3) an analytical treatment of the effect of the distributed silicon gate resistance and capacitance on the speed of DMOS transistors.

Lin, H. C.↗

NASA NTRS1979

AIFTDS stand-alone RMDU flight test report

The remote multiplexer/digitizer unit for the airborne integrated flight test data system was subjected to a flight test environment in order to study its dynamic response and that of its associated instrumentation circuitry during an actual flight test. The shielding schemes and instrumentation used are described and the data obtained are analyzed.

Wilner, D. O.↗

NASA NTRS1988

Radar-Data-Processing System

Report describes radar data system at NASA Western Aeronautical Test Range. System provides real-time and recorded data about flightpaths of research aircraft and Space Shuttle. Called RADATS, processes data from three radars simultaneously; interacts with system operator; enhances data by introducing corrections and smoothing; controls range, azimuth, and elevation of radars; and automatically calibrates itself before and after missions. Software classified into three kinds of programs: utility, real-time, and calibration. Equipment exhibited exceptional reliability. Software matured to become virtually trouble-free.

Anderson, Karl F.↗

NASA NTRS1989

Reduction of blade-vortex interaction noise using higher harmonic pitch control

An acoustics test using an aeroelastically scaled rotor was conducted to examine the effectiveness of higher harmonic blade pitch control for the reduction of impulsive blade-vortex interaction (BVI) noise. A four-bladed, 110 in. diameter, articulated rotor model was tested in a heavy gas (Freon-12) medium in Langley's Transonic Dynamics Tunnel. Noise and vibration measurements were made for a range of matched flight conditions, where prescribed (open-loop) higher harmonic pitch was superimposed on the normal (baseline) collective and cyclic trim pitch. For the inflow-microphone noise measurements, advantage was taken of the reverberance in the hard walled tunnel by using a sound power determination approach. Initial findings from on-line data processing for three of the test microphones are reported for a 4/rev (4P) collective pitch control for a range of input amplitudes and phases. By comparing these results to corresponding baseline (no control) conditions, significant noise reductions (4 to 5 dB) were found for low-speed descent conditions, where helicopter BVI noise is most intense. For other rotor flight conditions, the overall noise was found to increase. All cases show increased vibration levels.

Brooks, Thomas F.↗

NASA NTRS1990

Reduction of blade-vortex interaction noise through higher harmonic pitch control

Brooks, Thomas F.↗

NASA NTRS1994

FPCAS2D user's guide, version 1.0

The FPCAS2D computer code has been developed for aeroelastic stability analysis of bladed disks such as those in fans, compressors, turbines, propellers, or propfans. The aerodynamic analysis used in this code is based on the unsteady two-dimensional full potential equation which is solved for a cascade of blades. The structural analysis is based on a two degree-of-freedom rigid typical section model for each blade. Detailed explanations of the aerodynamic analysis, the numerical algorithms, and the aeroelastic analysis are not given in this report. This guide can be used to assist in the preparation of the input data required by the FPCAS2D code. A complete description of the input data is provided in this report. In addition, four test cases, including inputs and outputs, are provided.

Bakhle, Milind A.↗

NASA NTRS1995

A longitudinal aerodynamic data repeatability study for a commercial transport model test in the National Transonic Facility

A high Reynolds number investigation of a commercial transport model was conducted in the National Transonic Facility (NTF) at Langley Research Center. This investigation was part of a cooperative effort to test a 0.03-scale model of a Boeing 767 airplane in the NTF over a Mach number range of 0.70 to 0.86 and a Reynolds number range of 2.38 to 40.0 x 10(exp 6) based on the mean aerodynamic chord. One of several specific objectives of the current investigation was to evaluate the level of data repeatability attainable in the NTF. Data repeatability studies were performed at a Mach number of 0.80 with Reynolds numbers of 2.38, 4.45, and 40.0 x 10(exp 6) and also at a Mach number of 0.70 with a Reynolds number of 40.0 x 10(exp 6). Many test procedures and data corrections are addressed in this report, but the data presented do not include corrections for wall interference, model support interference, or model aeroelastic effects. Application of corrections for these three effects would not affect the results of this study because the corrections are systematic in nature and are more appropriately classified as sources of bias error. The repeatability of the longitudinal stability-axis force and moment data has been accessed. Coefficients of lift, drag, and pitching moment are shown to repeat well within the pretest goals of plus or minus 0.005, plus or minus 0.0001, and plus or minus 0.001, respectively, at a 95-percent confidence level over both short- and near-term periods.

Wahls, R. A.↗

NASA NTRS1998

Integrated Advanced Microwave Sounding Unit-A (AMSU-A). Engineering Test Report: METSAT A1 Signal Processor (P/N 1331670-2, S/N F03)

This report presents a description of tests performed, and the test data, for the A1 METSAT Signal Processor Assembly PN: 1331679-2, S/N F03. This assembly was tested in accordance with AE-26754, "METSAT Signal Processor Scan Drive Test and Integration Procedure." The objective is to demonstrate functionality of the signal processor prior to instrument integration.

Lund, D.↗

NASA NTRS2014

Elemental Water Impact Test: Phase 2 36-Inch Aluminum Tank Head

Spacecraft are being designed based on LS-DYNA simulations of water landing impacts. The Elemental Water Impact Test (EWIT) series was undertaken to assess the accuracy of LS-DYNA water impact simulations. EWIT Phase 2 featured a 36-inch aluminum tank head. The tank head was outfitted with one accelerometer, twelve pressure transducers, three string potentiometers, and four strain gages. The tank head was dropped from heights of 1 foot and 2 feet. The focus of this report is the correlation of analytical models against test data. As a measure of prediction accuracy, peak responses from the baseline LS-DYNA model were compared to peak responses from the tests.

Vassilakos, Gregory J.↗

NASA NTRS2015

Elemental Water Impact Test: Phase 1 20-Inch Hemisphere

Spacecraft are being designed based on LS-DYNA simulations of water landing impacts. The Elemental Water Impact Test (EWIT) series was undertaken to assess the accuracy of LS-DYNA water impact simulations. Phase 1 of the EWIT series featured water impact tests of a 20-inch hemisphere dropped from heights of 5 feet and 10 feet. The hemisphere was outfitted with an accelerometer and three pressure gages. The focus of this report is the correlation of analytical models against test data.

Vassilakos, Gregory J.↗

NASA NTRS2016

Helicopter Acoustic Flight Test with Altitude Variation and Maneuvers

A cooperative flight test campaign between NASA and the U.S. Army was performed from September 2014 to February 2015. The purposes of the testing were to: investigate the effects of altitude variation on noise generation, investigate the effects of gross weight variation on noise generation, establish the statistical variability in acoustic flight testing of helicopters, and characterize the effects of transient maneuvers on radiated noise for a medium-lift utility helicopter. This test was performed at three test sites (0, 4000, and 7000 feet above mean sea level) with two aircraft (AS350 SD1 and EH-60L) tested at each site. This report provides an overview of the test, documents the data acquired and describes the formats of the stored data.

Watts, Michael E.↗

NASA NTRSDate not supplied

Space-Cent: Studying the Physiological and Anatomical Effects of Centrifugation and Head Down Tilt: 2021 Update

BACKGROUND The objective of this study was to evaluate the cerebral and ocular physiological and anatomical effects of head-down tilt bedrest (HDBR) with and without daily artificial gravity (AG) in healthy subjects to provide novel insights into possible countermeasures for the Spaceflight Associated Neuro-ocular Syndrome (SANS). Previous long-term studies using the spaceflight analog of strict 6° HDBR for 30 days revealed changes in ocular structure, including optic disc edema. The effects of an AG countermeasure using intermittent centrifugation to restore upright hydrostatic gradients and reduce the ocular and brain anatomical effects has not been explored. METHODS The effects of 60-day exposure to simulated microgravity (6° HDBR) on the cerebral, ocular and vestibular systems with and without the intervention of daily 30 minute exposure to AG (short-arm centrifugation) was evaluated in 24 healthy subjects. Non-invasive measurements of cerebral blood flow, intracranial blood volume (near infrared spectroscopy, NIRS), cerebral and ocular structure (MRI and optical coherence tomography), internal jugular vein area (ultrasound), lateral ventricular volumes (MRI), intraocular pressure, and sensorimotor/vestibular (i.e. balance and coordination) systems were made during various time-points during the bedrest study. Additional measures with ultrasound and NIRS were made during centrifugation. RESULTS The study began in Spring 2019 and all 24 subjects completed the testing by end of 2019. Data analysis continues. We report the following updated results for 2021. MRI showed significant decreases in carotid artery flow, increases in brain and CSF volumes, and aqueductal flow velocities in all subjects in HDT compared to baseline supine, but no effects of the short duration AG. All groups showed increased posterior globe flattening during bedrest compared to baseline, without protection from AG. As previously reported we observed chorioretinal folds for the first time in a bedrest analog, as well as optic disc edema, with no protection from the short-term AG. Data from the study is now being transmitted to the NASA LSDA which will allow for future research. CONCLUSIONS The 6 degree HDBR analog produced significant changes in the anatomical and physiological functions of the brain and eye in healthy subjects. Daily 30 minute exposure to AG with short-arm centrifugation had significant transient effects on physiology of the cerebrovascular system, but was not sufficient to prevent the anatomical effects of HDBR on the brain and eye.

E M Bershad↗

NASA NTRS2022

Yuma 2022 Rotorcraft Acoustic Flight Test

A cooperative flight test campaign between U.S. Navy, Army, Marine Corps, and NASA was performed at Marine Corps Air Station (MCAS) Yuma from 19 January to 15 February 2022. The primary purpose of testing military vehicles was to characterize the acoustic signature of the MV-22 rotorcraft and Stalker unmanned aerial system for typical mission gross weight, configuration, and for a range of typical mission operating conditions. Additionally, a civilian MD530 vehicle was tested to characterize the acoustic emissions for both legacy blades and S411 main rotor blades. This report provides an overview of the test, documents the data acquired, and describes the formats of the stored data.

Acoustics↗

NASA NTRS1997

Flight Wing Surface Pressure and Boundary-Layer Data Report from the F-111 Smooth Variable-Camber Supercritical Mission Adaptive Wing

Flight tests were conducted using the advanced fighter technology integration F-111 (AFTI/F-111) aircraft modified with a variable-sweep supercritical mission adaptive wing (MAW). The MAW leading- and trailing-edge variable-camber surfaces were deflected in flight to provide a near-ideal wing camber shape for the flight condition. The MAW features smooth, flexible upper surfaces and fully enclosed lower surfaces, which distinguishes it from conventional flaps that have discontinuous surfaces and exposed or semi-exposed mechanisms. Upper and lower surface wing pressure distributions were measured along four streamwise rows on the right wing for cruise, maneuvering, and landing configurations. Boundary-layer measurements were obtained near the trailing edge for one of the rows. Cruise and maneuvering wing leading-edge sweeps were 26 deg for Mach numbers less than 1 and 45 deg or 58 deg for Mach numbers greater than 1. The landing wing sweep was 9 deg or 16 deg. Mach numbers ranged from 0.27 to 1.41, angles of attack from 2 deg to 13 deg, and Reynolds number per unit foot from 1.4 x 10(exp 6) to 6.5 x 10(exp 6). Leading-edge cambers ranged from O deg to 20 deg down, and trailing-edge cambers ranged from 1 deg up to 19 deg down. Wing deflection data for a Mach number of 0.85 are shown for three cambers. Wing pressure and boundary-layer data are given. Selected data comparisons are shown. Measured wing coordinates are given for three streamwise semispan locations for cruise camber and one spanwise location for maneuver camber.

Powers, Sheryll Goecke↗

NASA NTRS1993

Joint Acoustic Propagation Experiment (JAPE)

The Joint Acoustic Propagation Experiment (JAPE), performed under the auspices of NATO and the Acoustics Working Group, was conducted at White Sands Missile Range, New Mexico, USA, during the period 11-28 Jul. 1991. JAPE consisted of 220 trials using various acoustic sources including speakers, propane cannon, various types of military vehicles, helicopters, a 155mm howitzer, and static high explosives. Of primary importance to the performance of these tests was the intensive characterization of the atmosphere before and during the trials. Because of the wide range of interests on the part of the participants, JAPE was organized in such a manner to provide a broad cross section of test configurations. These included short and long range propagation from fixed and moving vehicles, terrain masking, and vehicle detection. A number of independent trials were also performed by individual participating agencies using the assets available during JAPE. These tests, while not documented in this report, provided substantial and important data to those groups. Perhaps the most significant feature of JAPE is the establishment of a permanent data base which can be used by not only the participants but by others interested in acoustics. A follow-on test was performed by NASA LaRC during the period 19-29 Aug. 1991 at the same location. These trials consisted of 59 overflights of supersonic aircraft in order to establish the relationship between atmospheric turbulence and the received sonic boom energy at the surface.

Carnes, Benny L.↗

NASA NTRS2023

Plug20 Test Report: Particle Image Velocimetry (PIV) Measurements

This report provides turbulent flow statistics made using particle image velocimetry (PIV) for several internally mixed exhaust systems with external plugs (Plug20 designs). The tests were conducted at the NASA Glenn Research Center’s Aero-Acoustic Propulsion Laboratory (AAPL) in May and June 2022. The corresponding acoustic data for the configurations and flows presented in this report can be found in an earlier Technical Memorandum, NASA/TM-20210010291, “Plug20 Test Report.” The Plug20 nozzle family was designed to represent commercial supersonic vehicles in the 2025 to 2035 timeframe with a bypass ratio around 4, having an internal mixer, with and without an external plug to improve nacelle boattail drag and shock. The flow conditions measured represent engine cycles for commercial supersonic aircraft at takeoff, having pressure ratios of 2.0 and heated fan and core streams, measured both with and without a flight stream surrounding the plume. A few unheated flow conditions were also tested to tie results to other baseline test results. The PIV measurements in both streamwise and cross-stream planes are described, along with brief analysis to visually catalog the contents and confirm their validity. In this analysis, the streamwise PIV is found to match benchmark datasets within its experimental error. However, the cross-stream turbulent quantities measured by two systems do not match each other or the streamwise measurements in amplitude—caution is required when using the cross-stream data. Data acquired and included in this report are (1) velocity statistics of the plumes in both a streamwise and several cross-stream planes, and (2) the hot nozzle geometry. Tabular forms of the data and computer-aided design (CAD) files of the hot geometry are presented as supplemental files described in Appendix A (TM-20230006779SUPPL1.zip) and Appendix B (TM-20230006779SUPPL2.zip).

Turbulence↗

NASA NTRS1993

High speed QPPM direct detection optical communication receivers for FSDD intersatellite links

This final report consists of four separate reports, one for each project involved in this contract. The first report is entitled '325 Mbps QPPM (quaternary pulse position modulation) Direct Detection Free Space Optical Communication Encoder and Receiver,' which was our primary work. The second report is entitled 'Test Results of the 325 Mbps QPPM High Speed Data Transmission GaAs ASICs,' which describes our work in connection with Galaxy Microsystems, Inc. who produced these ASICs for NASA. The third report, 'Receiver Performance Analysis of BPPM Optical Communication Systems Using 1.3 micron Wavelength Transmitter and InGaAs PIN Photodiodes,' was prepared at the request of the NASA/Photonics Branch for their efforts in upgrading the 1773 optical fiber data bus. The fourth report, 'Photomultiplier Tubes for Use at 1.064 micron Wavelength,' was also prepared at the request of the NASA/Photonics Branch as a research project.

Davidson, Frederic M.↗

NASA NTRS1928

Tank Tests of Twin Seaplane Floats

The following report contains the most essential data for the hydrodynamic portion of the twin-float problem. The following points were successfully investigated: 1) difference between stationary and nonstationary flow; 2) effect of the shape of the step; 3) effect of distance between floats; 4) effect of nose-heavy and tail-heavy moments; 5) effect of the shape of floats; 6) maneuverability.

FLOAT STEPS↗