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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 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
NASA NTRS1974

The petrology of the Apollo 17 mare basalts

Petrographic studies of Apollo 17 mare basalts indicate that 70215 and 71569 arrived at the lunar surface as liquids. Low-pressure melting experiments show that compositional variations within the Apollo 17 and Apollo 11 ophitic basalt suites may be generated by near-surface fractional crystallization of liquids with compositions similar to 70215 and 70017. High-pressure melting experiments show that liquids similar in composition to 70017 and 70215 can be generated by partial melting of an olivine+clinopyroxene+Fe-Ti-oxide source at depths of 100-150 km within the moon.

Longhi, J.↗
NASA NTRS1975

Spectroradiometric calibration techniques in the far ultraviolet - A stable emission source for the Lyman bands of molecular hydrogen

The problems associated with making accurate spectroradiometric measurements in the far UV region are sketched briefly. The equipment and methods that were developed for providing absolute sensitivity calibration of an Apollo 17 far UV spectrometer are described. The absolute reference standards were photoelectric diodes calibrated at the National Bureau of Standards. A complete vacuum optical facility, which included a premonochromator and stable UV light sources, was developed to calibrate the Apollo 17 instrument, and it has been used for a number of other tasks. Absolute radiometric calibrations between about 1200 and 1700 A were performed with an absolute accuracy of + or - 10%. The light source, which was designed to provide a very stable light output, is a low-pressure molecular hydrogen lamp in which the pressure is stabilized by thermal control of uranium hydride powder.-

Fastie, W. G.↗
NASA NTRS1975

Absolute calibration of a hydrogen discharge lamp in the vacuum ultraviolet

A low-pressure hydrogen discharge lamp was calibrated for radiant intensity in the vacuum ultraviolet spectral region on an absolute basis and was employed as a laboratory standard source in spectrograph calibrations. This calibration was accomplished through the use of a standard photodiode detector obtained from the National Bureau of Standards together with onsite measurements of spectral properties of optical components used. The stability of the light source for use in the calibration of vacuum ultraviolet spectrographs and optical systems was investigated and found to be amenable to laboratory applications. The lamp was studied for a range of operating parameters; the results indicate that with appropriate peripheral instrumentation, the light source can be used as a secondary laboratory standard source when operated under preset controlled conditions. Absolute intensity measurements were recorded for the wavelengths 127.7, 158.0, 177.5, and 195.0 nm for a time period of over 1 month, and the measurements were found to be repeatable to within 11 percent.

Nealy, J. E.↗
NASA NTRS1975

Properties of solid and gaseous hydrogen, based upon anisotropic pair interactions

Properties of H2 are studied on the basis of an analytic anisotropic potential deduced from atomic orbital and perturbation calculations. The low-pressure solid results are based on a spherical average of the anisotropic potential. The ground state energy and the pressure-volume relation are calculated. The metal-insulator phase transition pressure is predicted. Second virial coefficients are calculated for H2 and D2, as is the difference in second virial coefficients between ortho and para H2 and D2.

Etters, R. D.↗
NASA NTRS1975

Lightweight fuel cell powerplant for Tug

The design and characteristics of a lightweight powerplant based on advanced cell technology to meet the requirements of the Space Tug are described. The powerplant can be operated off low-pressure hydrogen and oxygen rocket propellant tanks and avoid the need for a dedicated reactant supply. Product water can be condensed or not, depending on vehicle or payload requirements. The heart of the unit, the fuel cell power section, consist of lightweight, series-connected, alkaline cells, while the power section contains accessory components for reactant conditioning, distribution, and venting, coolant circulation, passive product water removal and electric control. The proposed design offers at least a 50 per cent saving in powerplant weight, so that the total estimated powerplant dry weight including structure, tubing, wiring, interface connectors, and interface heat exchanger is 48 lb.

Handley, L. M.↗
NASA NTRS1976

Waveguide CO2 laser gain - Dependence on gas kinetic and discharge properties

A simple rate-equation approach is used to examine the gas-kinetic and discharge properties of waveguide CO2 lasers. The dependence of the population inversion and laser small-signal gain on gas pressure, gas mixture, pumping rate (discharge current), tube bore diameter, and wall temperature is calculated along with the dependence of laser tunability on the gas-kinetic properties and cavity losses. It is found that for low-loss cavities, the laser tunability may substantially exceed the molecular full width at half-maximum. Furthermore, the more helium-rich gas mixtures give greater tunability when cavity losses are small, and less tunability when cavity losses are large. By contrast with conventional lasers, the waveguide-laser transition is homogeneously broadened. Thus, the dependence of gain on gas pressure and other kinetic properties differs substantially from that predicted by scaling results from conventional low-pressure lasers.

Cohen, S. C.↗
NASA NTRS1975

Experimentally reproduced textures and mineral chemistries of high-titanium mare basalts

Many of the textures, morphologies, and mineral chemistries of the high-titanium mare basalts have been experimentally duplicated using single-stage cooling histories. Lunar high-titanium mare basalts are modeled in a 1 m thick gravitationally differentiating flow based on cooling rates, thermal models, and modal olivine contents. The low-pressure equilibrium phase relations of a synthetic high-titanium basalt composition were investigated as a function of oxygen fugacity, and petrographic criteria are developed for the recognition of phenocrysts which were present in the liquid at the time of eruption.

Usselman, T. M.↗
NASA NTRS1975

On the origin of high-Ti mare basalts

Analyses were conducted of sixteen Apollo 17 mare basalts for alkali, alkaline-earth, and rare-earth elements, Co, and Sc. The obtained data were utilized in a study concerning the nature of the igneous processes responsible for the chemical variations among the high-Ti, low-K basalts. Estimates were obtained regarding the abundances of the large-ion, lithophile elements in the source regions for the basalts. It is shown that the source regions could plausibly have been produced by processes believed to have occurred during the early history of the moon. Attention is given to chemical variations among the Apollo 17 mare basalts, near-surface (low-pressure) crystal fractionation, partial melting, limits on the extent of partial melting, and a summary of possible events leading to formation of high-Ti mare basalts.

Shih, C.-Y.↗
NASA NTRS1957

Nonmetallic Material Compatibility with Liquid Fluorine

Static tests were made on the compatibility of liquid fluorine with several nonmetallic materials at -3200 F and at pressures of 0 and 1500 pounds per square inch gage. The results are compared with those from previous work with gaseous fluorine at the same pressures, but at atmospheric temperature. In general, although environmental effects were not always consistent, reactivity was least with the low-temperature, low-pressure liquid fluorine. Reactivity was greatest with the warm, high-pressure gaseous fluorine. None of the liquids and greases tested was found to be entirely suitable for use in fluorine systems. Polytrifluorochloroethylene and N-43, the formula for which is (C4F9)3N, did not react with liquid fluorine at atmospheric pressure or 1500 pounds per square inch gage under static conditions, but they did react when injected into liquid fluorine at 1500 pounds per square inch gage; they also reacted with gaseous fluorine at 1500 pounds per square inch gage. While water did not react with liquid fluorine at 1500 pounds per square inch gage, it is known to react violently with fluorine under other conditions. The pipe-thread lubricant Q-Seal did not react with liquid fluorine, but did react with gaseous fluorine at 1500 pounds per square inch gage. Of the solids, ruby (Al2O3) and Teflon did not react under the test conditions. The results show that the compatibility of fluorine with nonmetals depends on the state of the fluorine and the system design.

Price, Harold G , Jr↗
NASA NTRS1926

Experimental investigation of the physical properties of medium and heavy oils, their vaporization and use in explosion engines. Part I

While little has been accomplished in obtaining an abundant supply of light oils from coal and heavy oils, progress has been made on engine design to make use of the heavier oils. Progress has been made in two different directions which are outlined in this paper: the group of engines with medium and high-pressure carburetion in the cylinder; and the group of engines with low-pressure carburetion of the heavy oils before reaching the cylinder.

OILS↗
NASA NTRS1940

Stability of Castering Wheels for Aircraft Landing Gears

A theoretical study was made of the shimmy of castering wheels. The theory is based on the discovery of a phenomenon called kinematic shimmy. Experimental checks, use being made of a model having low-pressure tires, are reported and the applicability of the results to full scale is discussed. Theoretical methods of estimating the spindle viscous damping and the spindle solid friction necessary to avoid shimmy are given. A new method of avoiding shimmy -- lateral freedom -- is introduced.

Kantrowitz, Arthur↗
NASA NTRS1953

Aerodynamic Forces and Loadings on Symmetrical Circular-Arc Airfoils with Plain Leading-Edge and Plain Trailing-Edge Flaps

An investigation has been made in the Langley two-dimensional low-turbulence tunnel and in the Langley two-dimensional low-pressure tunnel of 6- and 10-percent-thick symmetrical circular-arc airfoil sections at low Mach numbers and several Reynolds numbers. The airfoils were equipped with 0.15-chord plain leading-edge flaps and 0.20-chord plan trailing-edge flaps. The section lift and pitching-moment characteristics were determined for both airfoils with the flaps deflected individually and in combination. The section drag characteristics were obtained for the 6-percent-thick airfoil with the flaps partly deflected as low-drag-control flaps and for airfoils with the flaps neutral. Surface pressures were measured on the 6-percent-thick airfoil section with the flaps deflected either individually or in appropriate combination to furnish flap load and hinge-moment data applicable to the structural design of the airfoil. A generalized method is developed that permits the determination of the chordwise pressure distribution over sharp-edge airfoils with plain leading-edge flaps and plain trailing-edge flaps of arbitrary size and deflection.

Cahill, Jones F↗
NASA NTRS1931

Effect of viscosity in speed measurements with double-throat Venturi tubes

In order to clarify the viscosity effect some experiments were made in the Gottigen low-pressure tunnel with the Bruhn double-throat Venturi tube. This type of tunnel makes it possible to vary the pressure and thereby the density within wide limits and consequently, to examine the viscosity effect. This, however, did not impair the results because pressure and temperature were determined at different periods.

Peters, H↗
NASA NTRS1959

Review of Aircraft Altitude Errors Due to Static-Pressure Source and Description of Nose-Boom Installations for Aerodynamic Compensation of Error

A brief review of airplane altitude errors due to typical pressure installations at the fuselage nose, the wing tip, and the vertical fins is presented. A static-pressure tube designed to compensate for the position errors of fuselage-nose installations in the subsonic speed range is described. This type of tube has an ogival nose shape with the static-pressure orifices located in the low-pressure region near the tip. The results of wind-tunnel tests of these compensated tubes at two distances ahead of a model of an aircraft showed the position errors to be compensated to within 1/2 percent of the static pressure through a Mach number range up to about 1.0. This accuracy of sensing free-stream static pressure was extended up to a Mach number of about 1.15 by use of an orifice arrangement for producing approximate free-stream pressures at supersonic speeds and induced pressures for compensation of error at subsonic speeds.

Gracey, William↗
NASA NTRS1959

Tire-to-Surface Friction Especially Under Wet Conditions

The results of measurements of the maximum friction available in braking on various runway surfaces under various conditions is shown for a C-123B airplane and comparisons of measurements with a tire-friction cart on the same runways are made. The.results of studies of wet-surface friction made with a 12-inch-diameter low-pressure tire on a tire-friction treadmill, with an automobile tire on the tire-friction cart, and with a 44 x 13 extra-high-pressure type VII aircraft tire at the Langley landing-loads track are compared. Preliminary results of tests on the tire-friction treadmill under wet-surface conditions to determine the effect of the wiping action of the front wheel of a tandem-wheel arrangement on the friction available in braking for the rear wheel are given.

Sawyer, Richard H.↗
NASA NTRS1961

Alignment Charts for Transport Properties Viscosity, Thermal Conductivity, and Diffusion Coefficients for Nonpolar Gases and Gas Mixtures at Low Density

Alignment charts (nomographs) designed to permit rapid calculations of the low-pressure transport properties of nonpolar gases and gas mixtures are presented. Calculations for pure gases are based on the rigorous kinetic theory of gases as applied to a realistic intermolecular force law. Mixture viscosities and conductivities are calculated from good approximations derived from rigorous theory. The properties are calculable with a precision of 2 percent or better. Accuracy depends on how well the constants characterizing the Intermolecular force law are known; if constants are derived from experimental data, results should be accurate to 5 percent or better. Force constants are tabulated for 65 gases.

Brokaw, Richard S.↗
NASA NTRS1937

Stability of Castering Wheels for Aircraft Landing Gears, Special Report

In many installations of castering rubber-tired wheels there is a tendency for the wheel to oscillate violently about the spindle axis. This phenomenon, popularly called 'shimmy,' has occurred in some airplane tail wheels and has been corrected in two ways: first by the application of friction in the spindles of the tail wheels; and, second, by locking the wheels while taxiing at high speeds. Shimmy is common with the large wheels used as nose wheels in tricycle landing gears and, since it is impossible to lock the wheels, friction in the nose-wheel spindle has been the sole means of correction. Because the nose wheel is larger than the conventional tail wheel and usually carries a greater load, the larger amounts of spindle friction necessary to prevent shimmy are objectionable. the present paper presents a theoretical and experimental study of the problem of the stability of castering wheels for airplane landing gears. On the basis of simplified assumptions induced from experimental observations, a theoretical study has been made of the shimmy of castering wheels. The theory is based on the discovery of a phenomenon called 'kinematic shimmy' and is compared quantitatively with the results of model experiments. Experimental checks, using a model having low-pressure tires, are reported and the applicability of the results to full scale is discussed. Theoretical methods of estimating the spindle viscous damping and spindle solid friction necessary to avoid shimmy - lateral freedom - is introduced.

Kantrowitz, Arthur↗
NASA NTRS1961

Atmospheric Photochemistry

The upper atmosphere offers a vast photochemical laboratory free from solid surfaces, so all reactions take place in the gaseous phase. At 30 km altitude the pressure has fallen to about one-hundredth of that at ground level, and we shall, rather arbitrarily, regard the upper atmosphere as beginning at that height. By a little less than 100 km the pressure has fallen to 10(exp -3) mm Hg and is decreasing by a power of ten for every 15 km increase in altitude. Essentially we are concerned then with the photochemistry of a nitrogen-oxygen mixture under low-pressure conditions in which photo-ionization, as well as photodissociation, plays an important part. Account must also be taken of the presence of rare constituents, such as water vapour and its decomposition products, including particularly hydroxyl, oxides of carbon, methane and, strangely enough, sodium, lithium and calcium. Many curious and unfamiliar reactions occur in the upper atmosphere. Some of them are luminescent, causing the atmosphere to emit a dim light called the airglow. Others, between gaseous ions and neutral molecules, are almost a complete mystery at this time. Similar interesting phenomena must occur in other planetary atmospheres, and they might be predicted if sufficient chemical information were available.

Massey, Harrie↗