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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
All sourcesNASA NTRSDOE OSTI
NASA NTRS1973

High modulus filament wound vessels for cryogenic containers in spacecraft.

Compared to metallic vessels, filament-wound vessels for containment of cryogens and high pressure gases offer high potential weight savings for NASA spacecraft applications. Since carbon fiber/epoxy resin composites exhibit high strength-to-density ratios, high-cycle fatigue life, and excellent strain compatibility with internal metallic liners, filament-wound carbon fiber/epoxy resin composites were evaluated for application to cryogenic internal pressure vessels. Compared to room temperature values, the cryogenic strengths of the composites were reduced by about 15% at -423 F (with the exception of one composite) while moduli increased as much as 25%. Filament-wound carbon fiber/epoxy resin vessel specimens, made by three fabricators, defined and solved problems in the processing of these friable high-modulus fibers into structurally efficient vessel specimens.

Simon, R. A.↗
NASA NTRS1973

An electron-lens for opaque photocathodes.

It is possible to employ opaque photocathodes in image tubes having a special electromagnetic lens without the use of special internal image-forming optical lenses or mirrors. The special electron lens, having flat object and image planes, is found to provide excellent quality electron-optical image transfer. Stray light reflection inside the tube is expected to be less serious in this electron lens than in a conventional magnetically focused image tube lens due to the offset image plane, and due to the increased absorption of photons in opaque photocathode applications.

Johnson, C. B.↗
NASA NTRS1973

Orbiting Astronomical Observatory heat pipe flight performance data.

The paper describes preflight and inflight performance checkout of the three isothermalizer heat pipes onboard the OAO-C spacecraft. The three pipes are: an axially grooved pipe, a pedestal artery pipe, and a self-priming spiral artery pipe. All pipes are 1/2-inch diameter tube rolled into a 48-inch diameter hoop. They are constructed of aluminum and use ammonia as working fluid. Periodic inflight performance checks have been made since launch in August 1972. No degradation in performance of any of the pipes has been detected. The flight data are in excellent agreement with ground test data.

Harwell, W.↗
NASA NTRS1973

A simple method for studying slow crack growth.

A simple, inexpensive method for studying slow crack growth is described. The method entails measurements of load relaxation at constant displacement using a double torsion specimen. It is demonstrated that the data generated using this technique are in excellent agreement with data obtained using the more complex conventional techniques, for a range of materials - steel, titanium, glass, aluminum oxide, PMMA. These encouraging initial results suggest that additional and more detailed studies using this test procedure are merited.

Williams, D. P.↗
NASA NTRS1973

Relaxation of the V = 4,5,6,7, Sigma g/+/ vibrational levels of carbon monoxide studied by laser absorption.

The vibrational relaxation of individual vibration rotation levels of carbon monoxide behind incident shock waves of carbon monoxide has been studied by the method of laser absorption. For the particular vibrational states (V = 4 to 7) and temperature range (2500 to 5500 K) studied, it is concluded that the characteristic relaxation times are in excellent agreement with those obtained via previous measurements of 'bulk' gas properties. Further, the data furnish strong corroboration of the idea that the individual levels are in Boltzmann vibrational equilibrium during the relaxation process.

Chackerian, C., Jr.↗
NASA NTRS1973

Signature extension techniques applied to multispectral scanner data.

Review of a number of spectral radiance signature extension techniques based on the concept of preprocessing the data to reduce the effects due to atmospheric effects, scanner look angle, etc. One of the promising methods studied to date involves using a ratio preprocessing transformation wherein the signals generated in adjacent spectral bands are ratioed on a point-by-point basis prior to classification. This method is easily and efficiently implemented and tests to date have yielded excellent results. Signatures have been successfully extended over 100+ miles, four days, different times of day, and very different atmospheric conditions.

Nalepka, R. F.↗
NASA NTRS1973

Mesoscale history of a small patch of clear air turbulence.

Sequential analyses of data from a network of eight special rawinsonde stations 100 km apart demonstrate the important effects of mesoscale disturbances in a 2.5-hr episode of light-to-moderate clear air turbulence (CAT). The most significant feature was the development of two turbulent fields below and above a 2-km region of a wind minimum which passed over Wallops Island, Va., near 1530 GMT on Feb. 4, 1970. The small scale of these features precludes their detection in the standard 12-hr observation sequence. The rawinsonde network utilized, which incorporates fine-scale details in both space and time, is adequate to provide a very useful current CAT depiction and an excellent source for the preparation of a short-range forecast of CAT.

Boucher, R. J.↗
NASA NTRS1972

Reference data for thermocouple materials below the ice point.

Standard thermoelectric data have been determined for four thermocouple combinations used below the ice point: commercial types E, K, and T and the special combination of KP vs Au-0.07 at.% Fe. Power series coefficients necessary to generate E = f(T) data for these combinations are given. In addition, extensive tests were carried out to ascertain the variability between materials from different manufacturers. Typical wires processed for low-temperature usage often have slightly thermoelectric properties (up to 1%) from those, nominally identical, wires made for high-temperature applications. Generally, type E is the most satisfactory standardized commercial combination. The Au-0.07 at.% Fe material has been examined in particular detail, because it is not yet an ISA standard material. It has excellent sensitivity in the liquid helium/liquid hydrogen temperature range and a nearly linear thermovoltage at higher temperatures.

Sparks, L. L.↗
NASA NTRS1972

Studies of the performance of W-Re type thermocouples.

The effect of exposure of bare-wire and BeO-insulated commercial W-Re thermocouple materials to high temperatures in gaseous environments was investigated. The temperature range of interest was primarily 2000 to 2400 K, and the investigations were confined to thermocouple wires of 0.25 mm diameter. Thermoelements were examined for metallurgical structural changes and chemical changes by conventional methods. In the temperature range of interest, grain growth was inhibited in the chemically doped W-3% Re alloy, and excellent room-temperature ductility was retained subsequent to the exposure. The compatibility of high purity (in excess of 99.8%), sintered BeO insulators with the thermoelements differed, depending upon whether the BeO-insulated thermoelement assemblies were self-heated electrically or heated in a furnace; in tests in argon environments, highly reliable performance occurred when the assemblies were heated in a furnace. BeO-insulated W-3% Re vs W-25% Re thermocouples, constructed with degassed and aged materials, exhibited drifts equivalent to about 3 mK/hr during 1000 hours of exposure at 2073 K in argon while in the presence of tantalum.

Burns, G. W.↗
NASA NTRS1973

Development of an H2O atmosphere around Comet Kohoutek /1973f/ and its possible detection.

Although chemically stable 'parent molecules' for the observed radicals in comets, have been suspected for more than thirty years none of them has yet been observed spectroscopically. The newly discovered great comet Kohoutek may provide an excellent opportunity for directly observing a 'parent molecule' (namely, H2O) for the first time. The continuous development of a H2O atmosphere around the nucleus as the comet approaches the sun is discussed together with the detection of this atmosphere, using ground-based instruments and instruments carried in aircraft, balloons, and rockets.

Ip, W.-H.↗
NASA NTRS1972

Apollo 16 mission Report. Supplement 1: Apollo 16 guidance, navigation, and control system performance analysis report

The results are reported of additional studies which were conducted to supplement conclusions drawn in the MSC Mission Report and analyses which were not completed in time to meet the Mission Report dealine. A detailed evaluation of the Abort Guidance System sensor assembly and results from the investigation of the X gyro loop anomaly are included. Further evidence is presented substantiating the excellent LM IMU performance obtained from preliminary indications. A detailed study is presented of the procedural changes implemented on Apollo 16 to diminish the number and duration of interruptions to the CSM DAP attitude maneuver during P20 Option 5 operations.

Source record↗
NASA NTRS1973

Noise and wake structure measurements in a subsonic tip speed fan

The results of an experimental program are reported which show the effect of blade angle, tip speed, fan pressure ratio, and thrust on noise of a model fan of 0.457m (18 inches) diameter operating at subsonic tip speeds at pressure ratios between 1.06 and 1.15. The fan used in this study had 12 blades, 7 stator vanes, and a spacing between the rotor and stator of 1.85 blade chords. This fan was originally designed for aerodynamic testing and was considered a good performer. It was used in the noise test program as it incorporated features found to reduce noise in an earlier analytical parametric study. For a given pressure ratio the fan was shown to exhibit minimum noise at the blade angle and tip speed near that of maximum aerodynamic efficiency. Also, the noise level and spectrum character of this fan showed excellent correlation with scaled data of a similar larger diameter fan. Results of the program confirm the trends shown in the earlier analytical parametric study which showed that fan noise could be reduced for a given thrust and pressure ratio by increasing fan solidity, improving fan aerodynamic design, and operating the fan at an optimum subsonic tip speed. In addition to noise, the blade wake characteristics at the leading edge of the stator were measured in this program. At root and tip sections some difference between predicted and measured wakes was found. However comparisons between predicted and measured wakes at mid span locations was found to be good.

Magliozzi, B.↗
NASA NTRS1973

Synthesis of optically clear polymeric materials for high temperature windows

A polymer has been developed that has excellent potential for use as windows in spacecraft as well as conventional aircraft. This polymer, phenolphthalein polycarbonate, has outstanding thermal properties, e.g., in place of melting or burning, it produces an insulating charred foam that closes off transmission of radiant heat through the window. This fact, coupled with an oxygen index of 0.43 and a 177 C tensile strength of 58 mega Newtons/sq m, makes this polymer a prime candidate for further development. Pilot plant preparation in a 20 gallon Pfaudler kettle was accomplished and large test specimens were prepared for evaluations.

Pannell, C. E.↗
NASA NTRS1973

Low temperature mechanical properties, fractographic and metallographic evaluation of several alloy steels

The mechanical properties are presented of alloy steels, 4130, 4140, 4340, 6150, and 8740. Test specimens were manufactured from approximately 1.00 inch (2.54 cm) diameter bar stock which had been heat treated to two different hardness levels. The following mechanical tests were performed at temperatures of 80 F (+26.7 C), 0 F (-17.8 C), -100 F (-73 C), and -200 F (-129 C): (1) tensile test (Ultimate, yield, modulus, elongation, and reduction of area), (2) notched tensile test, (3) charpy V-notched impact test (impact energy), and (4) double shear strength test (ultimate and yield). The test data indicate excellent tensile strength, notched/unnotched tensile ratios, ductility, impact, and shear properties at all test temperatures, except at -200 F (-129 C) where the impact strength of the higher strength group of alloy steels, 4130 (Rc-37) and 4140 (Rc-44) decreased to approximately 9 ft. lbs. (12 joules) and 6 ft. lbs. (8 joules), respectively. Chemical, metallographic, and fractographic analyses were also performed to evaluate microstructure, microhardness and the effect of decrease in temperature on the ductile to brittle failure transition.

Montano, J. W.↗
NASA NTRS1973

Black silicate paints: Formulation and performance data on OSO-H

Formulations and general procedures are given for making and applying space environmentally, as well as atmospherically stable black silicate paints. Compositions are given which meet spacecraft self-contamination requirements, have excellent heat resistance, and are strongly semiconductive.

Schutt, J. B.↗
NASA NTRS1973

Transport analysis of measured neutron leakage spectra from spheres as tests of evaluated high energy cross sections

Integral tests of evaluated ENDF/B high-energy cross sections have been made by comparing measured and calculated neutron leakage flux spectra from spheres of various materials. An Am-Be (alpha,n) source was used to provide fast neutrons at the center of the test spheres of Be, CH2, Pb, Nb, Mo, Ta, and W. The absolute leakage flux spectra were measured in the energy range 0.5 to 12 MeV using a calibrated NE213 liquid scintillator neutron spectrometer. Absolute calculations of the spectra were made using version 3 ENDF/B cross sections and an S sub n discrete ordinates multigroup transport code. Generally excellent agreement was obtained for Be, CH2, Pb, and Mo, and good agreement was observed for Nb although discrepancies were observed for some energy ranges. Poor comparative results, obtained for Ta and W, are attributed to unsatisfactory nonelastic cross sections. The experimental sphere leakage flux spectra are tabulated and serve as possible benchmarks for these elements against which reevaluated cross sections may be tested.

Bogart, D. D.↗
NASA NTRS1973

Volcanic activity and satellite-detected thermal anomalies at Central American volcanoes

The author has identified the following significant results. A large nuee ardente eruption occurred at Santiaguito volcano, within the test area on 16 September 1973. Through a system of local observers, the eruption has been described, reported to the international scientific community, extent of affected area mapped, and the new ash sampled. A more extensive report on this event will be prepared. The eruption is an excellent example of the kind of volcanic situation in which satellite thermal imagery might be useful. The Santiaguito dome is a complex mass with a whole series of historically active vents. It's location makes access difficult, yet its activity is of great concern to large agricultural populations who live downslope. Santiaguito has produced a number of large eruptions with little apparent warning. In the earlier ground survey large thermal anomalies were identified at Santiaguito. There is no way of knowing whether satellite monitoring could have detected changes in thermal anomaly patterns related to this recent event, but the position of thermal anomalies on Santiaguito and any changes in their character would be relevant information.

Stoiber, R. E.↗