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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 829 records · Page 46
All sourcesNASA NTRSDOE OSTI
NASA NTRS1975

Comparisons of pilot performance in simulated and actual flight

Five highly experienced professional pilots performed instrument landing system approaches under simulated instrument flight conditions in a Cessna 172 airplane and in a Link-Singer GAT-1 simulator while under the influence of orally administered secobarbital (0, 100, and 200 mg). Tracking performance in two axes and airspeed control were evaluated continuously during each approach. Error and RMS variability were about half as large in the simulator as in the airplane. The observed data were more strongly associated with the drug level in the simulator than in the airplane. Further, the drug-related effects were more consistent in the simulator. Improvement in performance suggestive of learning effects were seen in the simulator, but not in actual flight.

Billings, C. E.↗
NASA NTRS1974

Solid state electro-optic color filter and iris

The electro-optic properties of lanthanum-modified lead zirconate titanate (PLZT) ferroelectric ceramic material are evaluated when utilized as a variable density and/or spectral filter in conjunction with a television scanning system. Emphasis was placed on the development of techniques and procedures for processing the PLZT disks and for applying efficient electrode structures. A number of samples were processed using different combinations of cleaning, electrode material, and deposition process. Best overall performance resulted from the direct evaporation of gold over chrome electrodes. A ruggedized mounting holder assembly was designed, fabricated, and tested. The assembly provides electrical contacts, high voltage protection, and support for the fragile PLZT disk, and permits mounting and optical alignment of the associated polarizers. Operational measurements of a PLZT sample mounted in the holder assembly were performed in conjunction with a television camera and the associated drive circuits. The data verified achievement of the elimination of the observed white-line effect.

Source record↗
NASA NTRS1979

Electronically-scanned pressure measurement system

Sensor and associated microcomputer-based data acquisition unit can measure up to 1,024 unknown pressures at data rates as high as 10 kHz with maximum system inaccuracies of + or - 0.25 percent of full scale. System can be calibrated in place, making it easy to calibrate between runs for high cost or short run time wind tunnel testing.

Basta, T., Jr.↗
NASA NTRS1978

Escort - A data acquisition and display system to support research testing

A combination of a central minicomputer and test-site microcomputers has been adopted to provide on-line data acquisition and display service for a large number of different research programs. By integrating the data acquisition and recording functions in the minicomputer/microcomputer system, rapidly updated displays of selected data in terms of engineering units may be obtained. The system described here is primarily designed for steady-state test conditions, but may also provide data on slow transients associated with changing experimental conditions. Application of the system to full-scale jet engine tests, ion thruster assessments and anechoic chamber analyses are mentioned.

Miller, R. L.↗
NASA NTRS1978

Sequential High-Resolution Wind Profile Measurements

Tropospheric flow and lower stratospheric flow as measured by 94 sequences of high-resolution Jimsphere balloon data are presented and discussed. The 70 and 24 sequential series are presented for the Kennedy Space Center, Florida, and Point Mugu, California, areas, respectively. Supplemental data, consisting of the associative temperature profiles and surface and 200 mb synoptic maps, are also presented. The measurements are discussed relative to both the engineering and disciplinary areas. An initial subjective analysis of mesoscale features observed on some sequences is presented.

Johnson, D. L.↗
NASA NTRS1979

Magnetic field studies at Jupiter by Voyager 1: Preliminary results

Results obtained by the Goddard Space Flight Center magnetometers on Voyager 1 concerning the large scale configuration of the Jovian bow shock and magnetopause, and the magnetic field in both the inner and outer magnetosphere are highlighted. There is evidence that a magnetic tail extending away from the planet on the nightside is formed by the solar wind-Jovian field interaction. This is much like Earth's magnetosphere but is a new configuration for Jupiter's magnetosphere not previously considered from earlier Pioneer data. Magnetic field perturbations associated with intense electrical currents (approximately 5 x 10 to the 6th power amps) flowing near or in the magnetic flux tube linking Jupiter with the satellite Io and induced by the relative motion between Io and the co-rotating Jovian magnetosphere are analyzed and interpreted. These currents may be an important source of heating the ionosphere and interior of Io through Joule dissipation.

Ness, N. F.↗
NASA NTRS1980

Overview on the study of the solar cycle from space

Recent insights into the workings of the solar system are reviewed as factors to be considered when formulating key questions to be answered during a large scale program to study the solar cycle. The main objectives of the Solar Cycle and Dynamics Mission are to determine the causes (physical origins and mechanisms) of the solar cycle and the effects of these mechanisms on the heliosphere, the vast region that includes the corona, interplanetary medium, and the terrestrial environment. The mission should be able to obtain synoptic data on solar variability associated with the cycle, and over at least a fraction of a single 11-year cycle.

Noyes, R. W.↗
NASA NTRS1978

FAA navigation program

The FAA navigation program, which includes two major activity areas: those associated with certification of navigation systems to meet current requirements and those associated with building the data base needed to define future system improvements is examined. The near term activities, including the VORTAC upgrading program, the development of the technical data base needed for certification of LORAN C and OMEGA as a part of the current air navigation system, and the development of area navigation standards are examined in regard to cost factors and user requirements. Future system activities discussed include analysis of alternative system configurations made up of system elements including VORTAC VOR-DME, OMEGA and differential OMEGA, LORAN C, and GPS. The interrelationships between the near and far term programs are discussed. A helicopter IFR program which includes an assessment of the operational suitability of several navigation system alternatives for meeting helicopter navigation requirements for CONUS and offshore operations is reported.

Blake, N. A.↗
NASA NTRS1981

Coronal streamers in the solar wind at 1 AU

Virtually all solar wind observing groups have reported substantial variations in the solar wind helium-hydrogen abundance ratio (A(He)). A study of Los Alamos Imp solar wind data has revealed an association between low A(He) and high proton density that occurs at low flow speeds and that is correlated with polarity reversals of the interplanetary magnetic field. The current investigation has the objective to present further examples of the low A(He), high proton density, low speed, magnetic field polarity association, and to document the common occurrence of multiple events lasting approximately 3-7 days. The results are presented of attempts to relate these events directly to maps or isophotes of solar coronal brightness at 1.5 solar radii. The results of the investigation suggest that a substantial fraction of the low-speed solar wind originates in coronal streamers, particularly near solar minimum.

Gosling, J. T.↗
NASA NTRS1981

Comet Tempel-Tuttle and the Leonid meteors

The distribution of dust surrounding periodic comet Tempel-Tuttle has been mapped by analyzing the associated Leonid meteor shower data over the 902-1969 interval. The majority of dust ejected from the parent comet evolves to a position lagging the comet and outside the comet's orbit. Hence, it appears that radiation pressure and planetary perturbations, rather than ejection processes, control the dynamic evolution of the Leonid particles. Significant Leonid meteor showers are possible roughly 2500 days before or after the parent comet reaches perihelion, but only if the comet passes closer than 0.025 AU inside or 0.010 AU outside the earth's orbit. Although the conditions in 1998-1999 are optimum for a significant Leonid meteor shower, the event is not certain because the dust particle distribution near the comet is far from uniform. The orbit of comet Tempel-Tuttle has been redetermined for the 1366-1966 observed interval.

Yeomans, D. K.↗
NASA NTRS1982

X-ray emission from the Carina Nebula and the associated early stars

New Einstein observations of the Carina Nebula show the extent of the diffuse X-ray nebula to be 1.1 deg E-W by 0.7 deg N-S. The diffuse X-ray emission is generally associated with optically bright regions, but the correlation is not exact. Emission is strongest from regions bordering the apparently overlying dust lane, indicating an interaction between the energetic material of the optical nebula and the region containing the dust. The diffuse X-rays are from hot gas with temperatures of about 10 million K, and electron densities of 0.1-1/cu cm. The energy to heat this gas probably comes from strong stellar winds of the early stars embedded in the nebula. X-rays from 15 O and W-R stars in the Carina OBI association have been detected. Data are consistent with the hypothesis that X-ray luminosity is equal to about 2.0 x 10 to the -7th of bolometric luminosity for all O stars in this region with remarkably little scatter. X-ray emission from the three W-R stars observed is significantly different. In particular, the WN6 star, HD 93162, has an X-ray luminosity equal to about 2.0 x 10 to the -6th of bolometer luminosity, a factor of 30 higher than for two other W-R stars in this nebula, and perhaps the highest X-ray luminosity/bolometric luminosity of any W-R star for which X-ray observations have been made.

Seward, F. D.↗
NASA NTRS1984

Differential, integral, and momentum-transfer cross sections for elastic electron scattering by neon - 5 to 100 eV

Relative elastic-scattering differential cross sections were measured in the 5-100-eV impact energy and 10-145 deg angular ranges. Normalization of these cross sections was achieved by utilizing accurate total electron-scattering cross sections. A phase-shift analysis of the angular distributions in terms of real phase shifts has been carried out. From the differential cross sections, momentum-transfer cross sections were obtained and the values of the critical energy and angle were established (associated with the lowest value of the differential cross section) as 62.5 + or - 2.5 eV and 101.7 deg + or - 1.5 deg, respectively. The present phase shifts, the critical parameters, and differential, integral, and momentum-transfer cross sections are compared to previous experimental and theoretical results. The error associated with the present data is about 10 percent.

Register, D. F.↗
NASA NTRS1984

The dependence of reflectance spectra of Mercury on surface terrain

Reflectance spectra of Mercury covering the spectral range of 0.3-1.1 micron, obtained during 1963-1976, were examined for any correlations with surface terrain. Mercury's 6.1385-deg/day rotational rate, the phases of the planet around maximum elongations, and bidirectional-reflectance-spectroscopy theory were used to identify the surface area associated with each spectrum. Data from 1974-1975, rereduced with improved standard-star-flux ratios, show a weak absorption band in the near infrared not seen in earlier analyses. Older spectra suggest that the western longitudes of the unimaged side of Mercury are similar to the rest of the planet. Spectra of the intercrater plains in the 0-90-deg quadrant suggest a possible absorption band. Spectra of areas dominated by Caloris Basin with the encompassing smooth plains may show Fe(2+) abundances in the soil comparable to lunar-highlands soil. No striking differences between spectra of intercrater plains and smooth plains are found. The absorption features seen in spectra of Mercury are generally weaker than features seen in lunar spectra.

Vilas, F.↗
NASA NTRS1984

Mixing and the dynamics of the deep chlorophyll maximum in Lake Tahoe

Chlorophyll-temperature profiles were measured across Lake Tahoe about every 10 days from April through July 1980. Analysis of the 123 profiles and associated productivity and nutrient data identified three important processes in the formation and dynamics of the deep chlorophyll maximum (DCM): turbulent diffusion, nutrient supply rate, and light availability. Seasonal variation in these three processes resulted in three regimes: a diffusion-dominated regime with a weak DCM, a variable-mixing regime with a pronounced, nutrient supply-dominated DCM, and a stable regime with a deep, moderate light availability-dominated DCM. The transition between the first two regimes occurred in about 10 days, the transition between the last two more gradually over about 3 weeks. The degree of spatial variability of the DCM was highest in the second regime and lowest in the third. These data indicate that the DCM in Lake Tahoe is constant in neither time nor space.

Abbott, M. R.↗
NASA NTRS1986

Dynamic loading on parallel shaft gears

A computer-based analysis of the dynamic effects of spur gear systems is presented. The method of analysis with its associated computer code is capable of determining the dynamic response of spur gear systems having involute tooth profiles and standard contact ratios. Various parameters affecting the system dynamic behavior are examined. Numerical results of the analysis are compared with semi-empirical formulae, AGMA (American Gear Manufacturers Association) formulae, and experimental data. A close correlation with the experimental data is obtained.

Lin, H. H. (edward)↗
NASA NTRS1986

Equatorial thermospheric measurements of temperatures and winds at Arequipa, Peru

Enhancement of FPI temperatures above quiet levels was observed a few hours after the start of magnetic activity. Magnitude of this enhancement is about 300 degrees. This is followed by relaxation to prestorm levels. Apparent average offset of RPI temperatures from mass spectrometer incoherent scatter radar by 100 to 200 degrees for relatively quiet times is also observed. There was a definite suggestion of a midnight thermal enhancement for April and August data, with a magnitude of about 100 degrees, seen in both 1983 and 1984 observations. There was a definite enhancement of 6300A surface brightness in the south as compared with other directions, probably connected to the tropical airglow arcs. Meridional winds were small (less than 25 m/s) throughout night. Indication of northward migration of the observed 6300A enhancement in the evening hours as observations approach local winter solstice. This is probably related to the observed poleward (to the south) meridional wind (of magnitude 50 m/s) in this period. Zonal component of winds always eastward, but speed approaches zero sooner near equinox than at summer solstice. Typical magnitude at peak is of order 100 to 150 m/s. Suggestion of zonal wind increase after twilight and recovery of 6300A emission for April data. Origin not clear but may be related to midnight thermal enhancement. Meridional wind virtually zero for equinox in 1983; shows evening flow towards winter hemisphere in early evening for solstice data. Suggestion of post-midnight surge in April 1984 data. No major effects associated with magnetic storm activity, but a suggestion of decrease in zonal component below nominal levels.

Meriwether, J. W., Jr.↗
NASA NTRS1987

Experimental studies on the tripping behavior of narrow T-stiffened flat plates subjected to hydrostatic pressure and underwater shock

An experimental investigation was conducted to determine the static and dynamic responses of a specific stiffened flat plate design. The air-backed rectangular flat plates of 6061-T6 aluminum with an externally machined longitudinal narrow-flanged T-stiffener and clamped boundary conditions were subjected to static loading by water hydropump pressure and shock loading from an eight pound TNT charge detonated underwater. The dynamic test plate was instrumented to measure transient strains and free field pressure. The static test plate was instrumented to measure transient strains, plate deflection, and pressure. Emphasis was placed upon forcing static and dynamic stiffener tripping, obtaining relevant strain and pressure data, and studying the associated plate-stiffener behavior.

Budweg, H. L.↗