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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 217 records · Page 12

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NASA NTRS1973

H2-O2 auxiliary power unit for Space Shuttle vehicles - A progress report.

Description of a program to establish technology readiness of hydrogen-oxygen (H2-O2) auxiliary power units for use on board the Space Shuttle orbiter vehicle. Fundamental objectives include experimentally establishing an acceptable propellant flow control method, verification of combustor stability, and adequate thermal management. An initial auxiliary power unit (APU) configuration with recycled hydrogen flow has been studied and revised toward greater simplicity and scaling ease. The selected APU is a recuperated open-cycle, turbine-driven unit. Series flow of cryogenic hydrogen removes internally-generated heat and heat from the hydraulic system. The revised configuration schematic and its calculated performance are reviewed. A weight comparison is made between the shuttle baseline hydrazine and H2-O2 APU systems, showing that hydrogen-oxygen APUs have the potential of increasing the payload of the Space Shuttle.

Joyce, J. P.↗

NASA NTRS1973

Revised tables of airspeed, altitude, and Mach number presented in the International system of units

Because inception of a national program to implement the International System of Units (SI) appears to be inevitable and imminent, the tables of airspeed, altitude, and Mach number prepared by Livingston and Gracey to serve for airspeed meter and altimeter calibrations and for the conversion of flight measurements of these quantities to related parameters - Mach number, true airspeed, equivalent airspeed, etc. - have been revised to the SI. Tables of airspeed in knots are also included because of the significance of this quantity in navigation. In addition, the data in the altitude tables have been revised to the U.S. Standard Atmosphere of 1962. The latter data reflect increased knowledge of the higher atmosphere and more precise determination of basic quantities, including the redefinition of the absolute thermodynamic temperature scale by the Tenth General Conference on Weights and Measures in 1954. The U.S. Standard Atmosphere, 1962, corresponds to the International Civil Aviation Organization (ICAO) Standard Atmosphere up to 20 kilometers (geopotential altitude). A table of conversion factors for various pressure units is presented in SI Units.

Benner, M. S.↗

NASA NTRS1973

Brayton heat exchanger unit development program (alternate design)

A Brayton Heat Exchanger Unit Alternate Design (BHXU-Alternate) consisting of a recuperator, a heat sink heat exchanger, and a gas ducting system, was designed and fabricated. The design was formulated to provide a high performance unit suitable for use in a long-life Brayton-cycle powerplant. Emphasis was on double containment against external leakage and leakage of the organic coolant into the gas stream. A parametric analysis and design study was performed to establish the optimum component configurations to achieve low weight and size and high reliability, while meeting the requirements of high effectiveness and low pressure drop. Layout studies and detailed mechanical and structural design were performed to obtain a flight-type packaging arrangement, including the close-coupled integration of the BHXU-Alternate with the Brayton Rotating Unit (BRU).

Duncan, J. D.↗

NASA NTRS1975

Short, unit-memory, Byte-oriented, binary convolutional codes having maximal free distance

It is shown that (n sub 0, k sub 0) convolutional codes with unit memory always achieve the largest free distance among all codes of the same rate k sub 0/n sub 0 and same number 2MK sub 0 of encoder states, where M is the encoder memory. A unit-memory code with maximal free distance is given at each place where this free distance exceeds that of the best code with k sub 0 and n sub 0 relatively prime, for all Mk sub 0 less than or equal to 6 and for R = 1/2, 1/3, 1/4, 2/3. It is shown that the unit-memory codes are byte-oriented in such a way as to be attractive for use in concatenated coding systems.

Lee, L. N.↗

NASA NTRS1975

Design and test of a flywheel energy storage unit for spacecraft application

This paper summarizes the design and test of a development flywheel energy storage device intended for spacecraft application. The flywheel unit is the prototype for the rotating assembly portion of an Integrated Power and Attitude Control System (IPACS). The paper includes a general description of the flywheel unit; specific design characteristics for the rotor and bearings, motor-generators, and electronics; an efficiency analysis; and test results for a research unit.

Cormack, A., III↗

NASA NTRS1975

A review of ride comfort studies in the United Kingdom

United Kingdom research which is relevant to the assessment of vehicle ride comfort was reviewed. The findings reported in approximately 80 research papers are outlined, and an index to the areas of application of these studies is provided. The data obtained by different research groups are compared, and it is concluded that, while there are some areas of general agreement, the findings obtained from previous United Kingdom research are insufficient to define a general purpose ride comfort evaluation procedure. The degree to which United Kingdom research supports the vibration evaluation procedure defined in the current International Standard on the evaluation of human exposure to whole-body vibration is discussed.

Griffin, M. J.↗

NASA NTRS1977

Lunar spectral units - A northern hemispheric mosaic

The distribution of lunar spectral units has been studied with the aid of multispectral imaging using silicon vidicons. The employed method has been developed over the last few years. The lunar observations used in the study had been made on May 7, 1974 (UT) at the Table Mountain Observatory. Four narrow bandpass interference filters centered at 0.38, 0.56, 0.85, and 1.05 micrometers were used. In the data displays presented the large differences (as in visual albedo) between the mare and the uplands have been deliberately minimized to allow small variations between these two major regions to be studied. Most of the spectral units are quite distinct, with relatively sharp boundaries. Attention is given to the general characteristics of spectral units, the distribution of mare basalt types, and the distribution of orange glass and dark mantling material.

Johnson, T. V.↗

NASA NTRS1975

Geochemical and geological units of Mare Humorum - Definition using remote sensing and lunar sample information

Mare Humorum has been found to contain at least nine distinct units. Mare basalt units typical of those at the Apollo 12 and 15 sites and central Mare Serenitatis exist also in Mare Humorum, but the early, high-titanium basalts typical of Mare Tranquillitatis and southeast Mare Serenitatis are absent. Basalts containing about 5% TiO2, not sampled at any Apollo site, also are found in Mare Humorum. Emplacement of extensive low-titanium basalts occurred in Mare Humorum in roughly the same period as emplacement of similar basalts at Apollo 12 and central Mare Serenitatis. These were followed by emplacement of the higher titanium basalts during a later period. These and other units are characterized and their extent mapped using a combination of remote sensing and Apollo sample studies. The results are interpreted in the context of the evolution of the Humorum region.

Pieters, C.↗

NASA NTRS1964

Chassis unit insert tightening-extract device

The invention relates to the insertion and extraction of rack mounted electronic units and in particular to a screw thread insert tightening and extract device, for chassis units having a collar which may be rotatably positioned manually for the insert tightening or extraction of various associated chassis units, as desired.

Haerther, L. W.↗

NASA NTRS1980

Storage peak gas-turbine power unit

A storage gas-turbine power plant using a two-cylinder compressor with intermediate cooling is studied. On the basis of measured characteristics of a .25 Mw compressor computer calculations of the parameters of the loading process of a constant capacity storage unit (05.3 million cu m) were carried out. The required compressor power as a function of time with and without final cooling was computed. Parameters of maximum loading and discharging of the storage unit were calculated, and it was found that for the complete loading of a fully unloaded storage unit, a capacity of 1 to 1.5 million cubic meters is required, depending on the final cooling.

Tsinkotski, B.↗

NASA NTRS1980

The surface of Io - Geologic units, morphology, and tectonics

The geologic units, morphology and tectonics evident on a preliminary geological map obtained from best-resolution Voyager 1 images and a preliminary pictorial map of the surface of Io are discussed. Nine volcanic units are identified on the surface which are composed of mountain materials, intervent, layered and eroded layered plains, and wall and floor, pit crater flow, shield crater flow, fissure flow and crater cone units associated with volcanic vents, along with seven types of structural features. The cumulative volcanic crater size distribution of 170 Ionian vents with craters greater than 14 km is similar to that of impact craters on other solar system bodies, with a surplus of small craters and a preponderance of volcanic vents in the Io equatorial zone. The observed surface morphologies provide evidence for a mixture of silicates and sulfur as the dominant surface material. Lineaments and grabens are also apparent on the surface, in a common planetary grid pattern.

Schaber, G. G.↗

NASA NTRS1981

Description of a dual fail-operational redundant strapdown inertial measurement unit for integrated avionics systems research

Attention is given to a redundant strapdown inertial measurement unit for integrated avionics. The system consists of four two-degree-of-freedom turned rotor gyros and four two-degree-of-freedom accelerometers in a skewed and separable semi-octahedral array. The unit is coupled through instrument electronics to two flight computers which compensate sensor errors. The flight computers are interfaced to the microprocessors and process failure detection, isolation, redundancy management and flight control/navigation algorithms. The unit provides dual fail-operational performance and has data processing frequencies consistent with integrated avionics concepts presently planned.

Bryant, W. H.↗

NASA NTRS1981

Description of a dual fail operational redundant strapdown inertial measurement unit for integrated avionics systems research

An experimental redundant strapdown inertial measurement unit (RSDIMU) is developed as a link to satisfy safety and reliability considerations in the integrated avionics concept. The unit includes four two degree-of-freedom tuned rotor gyros, and four accelerometers in a skewed and separable semioctahedral array. These sensors are coupled to four microprocessors which compensate sensor errors. These microprocessors are interfaced with two flight computers which process failure detection, isolation, redundancy management, and general flight control/navigation algorithms. Since the RSDIMU is a developmental unit, it is imperative that the flight computers provide special visibility and facility in algorithm modification.

Bryant, W. H.↗

NASA NTRS1983

VLSI Unit for Two-Dimensional Convolutions

Universal logic structure allows same VLSI chip to be used for variety of computational functions required for two dimensional convolutions. Fast polynomial transform technique is extended into tree computational structure composed of two units: fast polynomial transform (FPT) unit and Chinese remainder theorem (CRT) computational unit.

Liu, K. Y.↗

NASA NTRS1980

Government financial support for civil aircraft research, technology and development in four European countries and the United States

Data on the levels of government financial support for civil aircraft airframe and engine (CAAE) research and technology (R&T) in the United States and Europe (United Kingdom, West Germany, France and The Netherlands) and means of comparing these levels are provided. Data are presented for the years 1974-1977. European R&T expenditure data were obtained through visits to each of the four European countries, to the Washington office of the European Communities, and by a search of applicable literature. CAAE R&T expenditure data for the United States were obtained from NASA and Federal Aviation Administration (FAA).

Chandler, B.↗

NASA NTRS1984

Optical residue addition and storage units using a Hughes liquid crystal light valve

Optical addition and storage units are described in this paper. These units are implemented using the Hughes Liquid Crystal Light Valve (LCLV) as a spatial light modulator using residue arithmetic for a numerical representation. The main hardware components of the design, besides the light valve, include an array of single-mode optical fibers that provide input information, a polarizing prism in combination with quarter-wave and half-wave retarders for residue arithmetic implementation in the adder, and a holographic array for spatial stability in the storage unit.

Habiby, S. F.↗

NASA NTRS1983

Evaluation of the effects of the seasonal variation of solar elevation angle and azimuth on the processes of digital filtering and thematic classification of relief units

The effects of the seasonal variation of illumination over digital processing of LANDSAT images are evaluated. Two sets of LANDSAT data referring to the orbit 150 and row 28 were selected with illumination parameters varying from 43 deg to 64 deg for azimuth and from 30 deg to 36 deg for solar elevation respectively. IMAGE-100 system permitted the digital processing of LANDSAT data. Original images were transformed by means of digital filtering so as to enhance their spatial features. The resulting images were used to obtain an unsupervised classification of relief units. Topographic variables (declivity, altitude, relief range and slope length) were used to identify the true relief units existing on the ground. The LANDSAT over pass data show that digital processing is highly affected by illumination geometry, and there is no correspondence between relief units as defined by spectral features and those resulting from topographic features.

Parada, N. D. J.↗

NASA NTRS1984

The design and development of a solar tracking unit

The solar tracking unit was developed to support the Laser Heterodyne Spectrometer (LHS) airborne instrument, but has application to a general class of airborne solar occultation research instruments. The unit consists of a mirror mounted on two gimbals, one of which is hollow. The mirror reflects a 7.6 cm (3.0 in.) diameter beam of sunlight through the hollow gimbal into the research instrument optical axis. A portion of the reflected sunlight is directed into a tracking telescope which uses a four quadrant silicon detector to produce the servo error signals. The colinearity of the tracker output beam and the research instrument optical axis is maintained to better than + or - 1 arc-minute. The unit is microcomputer controlled and is capable of stand alone operation, including automatic Sun acquisition or operation under the control of the research instrument.

Jones, I. W.↗