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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 469 records · Page 26
All sourcesNASA NTRSDOE OSTI
NASA NTRS1984

Wind loading on solar concentrators: Some general considerations

A survey was completed to examine the problems and complications arising from wind loading on solar concentrators. Wind loading is site specific and has an important bearing on the design, cost, performance, operation and maintenance, safety, survival, and replacement of solar collecting systems. Emphasis herein is on paraboloidal, two-axis tracking systems. Thermal receiver problems also are discussed. Wind characteristics are discussed from a general point of view. Current methods for determining design wind speed are reviewed. Aerodynamic coefficients are defined and illustrative examples are presented. Wind tunnel testing is discussed, and environmental wind tunnels are reviewed. Recent results on heliostat arrays are reviewed as well. Aeroelasticity in relation to structural design is discussed briefly.

Roschke, E. J.↗
NASA NTRS1984

Satellite servicing: A business opportunity?

The possibilities of satellite servicing as a business opportunity are examined. The service rate which a user must be charged to yield a reasonable return is derived and then compared against the market's willingness to pay that rate. Steps taken to provide the basis from which the service rate could be derived include: (1) constructing a hypothetical on orbit servicing business offering both on orbit and associated ground services; (2) estimating the total on orbit service business potential by analyzing mission models to the year 2000; and (3) setting up ground rules to bound the conduct of the business. Using this basic information service demand (business volume) cost to set up the business, costs for operation and maintenance tax rates and desired rate of return are estimated to determine the user charge. Sensitivity of the service rate to various parameters are also assessed. The time span for the business venture runs from 1986 through 2000 with service to 1991 provided via the orbiter and by a space station beyond 1991. This point analysis shows about five years of negative cash flow, with steady profits thereafter.

Wong, R. E.↗
NASA NTRS1984

Application of the Hardman methodology to the Single Channel Ground-Airborne Radio System (SINCGARS)

The HARDMAN methodology was applied to the various configurations of employment for an emerging Army multipurpose communications system. The methodology was used to analyze the manpower, personnel and training (MPT) requirements and associated costs, of the system concepts responsive to the Army's requirement for the Single Channel Ground-Airborne Radio System (SINCGARS). The scope of the application includes the analysis of two conceptual designs Cincinnati Electronics and ITT Aerospace/Optical Division for operating and maintenance support addressed through the general support maintenance echelon.

Source record↗
NASA NTRS1985

A 34 ampere-hour nickel-cadmium minimum trickle charge testing

The current rates used for trickle charging batteries are critical in maintaining a full charge and in preventing an overcharge condition. The importance of the trickle charge rate comes from the design, maintenance and operational requirements of an electrical power system. The results of minimum trickle charge testing performed on six 34 ampere-hour, nickel-cadmium cells manufactured by General Electric are described. The purpose of the testing was to identify the minimum trickle charge rates at temperatures of 15 C and 30 C.

Timmerman, P. J.↗
NASA NTRS1985

Practical aspects of photovoltaic technology, applications and cost (revised)

The purpose of this text is to provide the reader with the background, understanding, and computational tools needed to master the practical aspects of photovoltaic (PV) technology, application, and cost. The focus is on stand-alone, silicon solar cell, flat-plate systems in the range of 1 to 25 kWh/day output. Technology topics covered include operation and performance of each of the major system components (e.g., modules, array, battery, regulators, controls, and instrumentation), safety, installation, operation and maintenance, and electrical loads. Application experience and trends are presented. Indices of electrical service performance - reliability, availability, and voltage control - are discussed, and the known service performance of central station electric grid, diesel-generator, and PV stand-alone systems are compared. PV system sizing methods are reviewed and compared, and a procedure for rapid sizing is described and illustrated by the use of several sample cases. The rapid sizing procedure yields an array and battery size that corresponds to a minimum cost system for a given load requirement, insulation condition, and desired level of service performance. PV system capital cost and levelized energy cost are derived as functions of service performance and insulation. Estimates of future trends in PV system costs are made.

Rosenblum, L.↗
NASA NTRS1984

Magnetically suspended Stirling cryogenic space refrigerator Test results

In 1979, a project leading to the development of a Stirling type cryogenic refrigerator for spaceborne application was initiated. The refrigerator is to generate five watts of net cooling at a temperature of 65 K. An operation without maintenance for a period of five years is required. A novel approach was selected for meeting the life requirement, taking into account an electromagnetic suspension of the moving parts. The fabrication of the hardware has now been completed and the performance of the refrigerator has been measured. The present paper provides a short review of the Stirling cycle, a description of the refrigerator design, and a summary of the test results. The new refrigerator configuration contains four major features, including a purely rectilinear drive, magnetic bearings, clearance seals, and all metal/ceramic working space surfaces. The displacer and the piston are supported and guided by magnetic bearings. The magnetic bearing consists of a set of electromagnetic actuators and radial position transducers.

Daniels, A.↗
NASA NTRS1985

Photovoltaic performance models - A report card

Models for the analysis of photovoltaic (PV) systems' designs, implementation policies, and economic performance, have proliferated while keeping pace with rapid changes in basic PV technology and extensive empirical data compiled for such systems' performance. Attention is presently given to the results of a comparative assessment of ten well documented and widely used models, which range in complexity from first-order approximations of PV system performance to in-depth, circuit-level characterizations. The comparisons were made on the basis of the performance of their subsystem, as well as system, elements. The models fall into three categories in light of their degree of aggregation into subsystems: (1) simplified models for first-order calculation of system performance, with easily met input requirements but limited capability to address more than a small variety of design considerations; (2) models simulating PV systems in greater detail, encompassing types primarily intended for either concentrator-incorporating or flat plate collector PV systems; and (3) models not specifically designed for PV system performance modeling, but applicable to aspects of electrical system design. Models ignoring subsystem failure or degradation are noted to exclude operating and maintenance characteristics as well.

Smith, J. H.↗
NASA NTRS1985

Laser angle sensor

A laser angle measurement system was designed and fabricated for NASA Langley Research Center. The instrument is a fringe counting interferometer that monitors the pitch attitude of a model in a wind tunnel. A laser source and detector are mounted above the model. Interference fringes are generated by a small passive element on the model. The fringe count is accumulated and displayed by a processor in the wind tunnel control room. This report includes optical and electrical schematics, system maintenance and operation procedures.

Pond, C. R.↗
NASA NTRS1985

CELCAP: A Computer Model for Cogeneration System Analysis

A description of the CELCAP cogeneration analysis program is presented. A detailed description of the methodology used by the Naval Civil Engineering Laboratory in developing the CELCAP code and the procedures for analyzing cogeneration systems for a given user are given. The four engines modeled in CELCAP are: gas turbine with exhaust heat boiler, diesel engine with waste heat boiler, single automatic-extraction steam turbine, and back-pressure steam turbine. Both the design point and part-load performances are taken into account in the engine models. The load model describes how the hourly electric and steam demand of the user is represented by 24 hourly profiles. The economic model describes how the annual and life-cycle operating costs that include the costs of fuel, purchased electricity, and operation and maintenance of engines and boilers are calculated. The CELCAP code structure and principal functions of the code are described to how the various components of the code are related to each other. Three examples of the application of the CELCAP code are given to illustrate the versatility of the code. The examples shown represent cases of system selection, system modification, and system optimization.

Source record↗
NASA NTRS1985

Some key considerations in evolving a computer system and software engineering support environment for the space station program

The space station data management system involves networks of computing resources that must work cooperatively and reliably over an indefinite life span. This program requires a long schedule of modular growth and an even longer period of maintenance and operation. The development and operation of space station computing resources will involve a spectrum of systems and software life cycle activities distributed across a variety of hosts, an integration, verification, and validation host with test bed, and distributed targets. The requirement for the early establishment and use of an apporopriate Computer Systems and Software Engineering Support Environment is identified. This environment will support the Research and Development Productivity challenges presented by the space station computing system.

Mckay, C. W.↗
NASA NTRS1985

A comparison of 8.415-, 32.0- and 565646-GHz deep space telemetry links

An economic and performance comparison is made of spacecraft telecommunication links at 8.415, 32.0, and 565646 GHz (0.53-micron wavelength) for the return of 3.43 x 10 to the 11th power bits from a Saturn Orbiter/Titan Probe mission in year 2000. Technical performance and costs for both ends of the links are included. Spacecraft antenna or telescope efficiencies, pointing losses, ground-based or Earth-orbiting relay terminals efficiencies, noise temperatures, recurring and nonrecurring engineering, and maintenance and operations costs are modeled. Weather effects, dc-to-RF or laser power conversion efficiencies, gravity and other environment distortions gain reductions, and the cost of pointing and tracking are analyzed. The effort is focused primarily on the microwave frequency links. There are large uncertainties in the cost results, but conclusions indicate that for a mid-1990's launch, the Ka-band system is as cost effective as X-band. The Ka-band system has a data rate advantage as compared to the X-band system for the same dc power input to the spacecraft. The magnitude of the advantage is a complex function of the weather at the DSN stations and the elevation angle of the ground antenna. A simple numerical comparison of the advantage is difficult and curves are provided. The optical frequency link is more costly based on the launch-to-orbit costs for the orbiting terminal. A more detailed study of the optical system is recommended to quantify astrometric tracking benefits and improve the accuracy of the cost estimate.

Dickinson, R. M.↗
NASA NTRS1985

Onsite 40-kilowatt fuel cell power plant manufacturing and field test program

A joint Gas Research Institute and U.S. Department of Energy Program was initiated in 1982 to evaluate the use of fuel cell power systems for on-site energy service. Forty-six 40 kW fuel cell power plants were manufactured at the United Technologies Corporation facility in South Windsor, Connecticut, and are being delivered to host utilities and other program participants in the United States and Japan for field testing. The construction of the 46 fully-integrated power plants was completed in January 1985 within the constraints of the contract plan. The program has provided significant experience in the manufacture, acceptance testing, deployment, and support of on-site fuel cell systems. Initial field test results also show that these experimental power plants meet the performance and environmental requirements of a commercial specification. This Interim Report encompasses the design and manufacturing phases of the 40 kW Power Plant Manufacturing and Field Test program. The contract between UTC and NASA also provides UTC field engineering support to the host utilities, training programs and associated manuals for utility operating and maintenance personnel, spare parts support for a defined test period, and testing at UTC of a power plant made available from a preceding program phase. These activities are ongoing and will be reported subsequently.

Source record↗
NASA NTRS1985

A sensitivity analysis of central flat-plate photovoltaic systems and implications for national photovoltaics program planning

The sensitivity of the National Photovoltaic Research Program goals to changes in individual photovoltaic system parameters is explored. Using the relationship between lifetime cost and system performance parameters, tests were made to see how overall photovoltaic system energy costs are affected by changes in the goals set for module cost and efficiency, system component costs and efficiencies, operation and maintenance costs, and indirect costs. The results are presented in tables and figures for easy reference.

Crosetti, M. R.↗
NASA NTRS1985

Space station data system analysis/architecture study. Task 2: Options development, DR-5. Volume 3: Programmatic options

Task 2 in the Space Station Data System (SSDS) Analysis/Architecture Study is the development of an information base that will support the conduct of trade studies and provide sufficient data to make design/programmatic decisions. This volume identifies the preferred options in the programmatic category and characterizes these options with respect to performance attributes, constraints, costs, and risks. The programmatic category includes methods used to administrate/manage the development, operation and maintenance of the SSDS. The specific areas discussed include standardization/commonality; systems management; and systems development, including hardware procurement, software development and system integration, test and verification.

Source record↗
NASA NTRS1985

Cost containment and KSC Shuttle facilities or cost containment and aerospace construction

This presentation has the objective to show examples of Cost Containment of Aerospace Construction at Kennedy Space Center (KSC), taking into account four major levels of Project Development of the Space Shuttle Facilities. The levels are related to conceptual criteria and site selection, the design of construction and ground support equipment, the construction of facilities and ground support equipment (GSE), and operation and maintenance. Examples of cost containment are discussed. The continued reduction of processing time from landing to launching represents a demonstration of the success of the cost containment methods. Attention is given to the factors which led to the selection of KSC, the use of Cost Engineering, the employment of the Construction Management Concept, and the use of Computer Aided Design/Drafting.

Brown, J. A.↗
NASA NTRS1986

Astronomy on a manned Mars mission

Three extra-solar-system astronomical experiments onboard a manned Mars mission are proposed. First, a modest, 50 cm aperture optical-ultraviolet-infrared telescope (or pair used as an interferometer) coupled with the Mars-Sun baseline would increase the number (by a factor of 3.4) and a volume of stars with accurately measured distances via stellar parallax and, therefore, greatly improve upon the cosmic distance scale; the darker sky at Mars would also provide nearly a full astronomical magnitude deeper images of distant and low brightness objects (limited by zodiacal light). Second, a gamma-ray burst detector coupled with similar detectors in other parts of the solar system will be used to reduce the position error boxes and to study the nature of these energetic sources. Third, the long baselines on a Mars mission radio interferometer will provide a view of the radio universe at unprescedented resolution, 4 x 10 to the minus 9th arcsec at 1 mm wavelength, which can potentially resolve the engine in nearby active galaxies. Each of these experiments is relatively inexpensive, taking advantage of the human presence for operation and maintenance, and the long Earth to Mars baseline.

Burns, Jack O.↗
NASA NTRS1987

Beam waveguides in the Deep Space Network

A beam waveguide is a mechanism for guiding electromagnetic radiation from one part of an antenna to another through a series of reflectors. Appropriate placement of reflectors on an antenna allows a beam to be guided around the elevation axis and/or below the alidade. The beam waveguide permits placement of all electronics in a room on the alidade below the elevation axis, or below the alidade; feed horn covers to be protected from the weather; and feed electronics to be in spacious rooms rather than in crowded cones, and always level rather than tipping with change in elevation angle. These factors can lead to lower costs in implementation such as Ka-band, better antenna performance at X-band, more efficient and stable performance of transmitters and receivers, and lower maintenance and operating costs. Studies are underway to determine methods for converting the major antennas of the Deep Space Network (DSN) to beam waveguide operations by 1995.

Clauss, R. C.↗
NASA NTRS1987

Product assurance policies and procedures for flight dynamics software development

The product assurance policies and procedures necessary to support flight dynamics software development projects for Goddard Space Flight Center are presented. The quality assurance and configuration management methods and tools for each phase of the software development life cycles are described, from requirements analysis through acceptance testing; maintenance and operation are not addressed.

Perry, Sandra↗