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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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Multilayer insulation of prefabricated panels is developed for cryogenic storage tanks. System utilizes panels of aluminized Mylar separated by sheets of low conductivity polyurethane foam. Panels are self-evacuated by cryopumping of gaseous carbon dioxide at time of use.
Prefabricated multilayered self-evacuating insulation panels using gas with low vapor pressure at cryogenic temperatures for application to storage of cryogens
Acoustic emission data were obtained from three point bend fracture toughness specimens of 12-nickel maraging steel, and two pressure vessels of the same material. One of the pressure vessels contained a prefabricated flaw which was extended and sharpened by fatigue cycling. It is shown that the flawed vessel had similar characteristics to the fracture specimens, thereby allowing estimates to be made of its nearness to failure during a proof test. Both the flawed and unflawed pressure vessel survived the proof pressure and 5 cycles to the working pressure, but it was apparent from the acoustic emission response during the proof cycle and the 5 cycles to the working pressure that the flawed vessel was very near failure. The flawed vessel did not survive a second cycle to the proof pressure before failure due to flaw extension through the wall (causing a leak).
High-temperature, reusable surface insulation tiles are repaired quickly and economically using prefabricated tile plugs.
The design of large, space-based power generation satellites is strongly influenced by the transportation modes available and the assembly methods adopted. Flight plans for assembly are explored using the Space Shuttle as the transport vehicle. Future heavy-lift launch systems are postulated, and their impact on assembly cost of operational Solar Satellite Power Stations (SSPS) presented. Sensitivity to various levels of ground detail parts prefabrication are compared to corresponding levels of orbital fabrication. Assumptions concerning the degree of human skills are outlined, and related to the method of assembly. Cost comparisons and recommendations for continued studies are developed.
Development of inside diameter slicing technology to significantly increase the number of useable slices per inch of crystal over industry practice is discussed. The required reduction of both blade and slice thickness is to be accomplished by a combination of three key elements of slicing technology: (1) ingot rotation with minimum exposed blade area; (2) dynamic cutting edge control; and (3) the use of prefabricated insert blades. Design modifications on a slicing saw with microprocessor controls and hardware fabrication to complete this conversion were initiated. Several runs were conducted on the engineering saw incorporating the method of ingot rotation. Ingots with diameters up to six inches were sliced successfully on a production saw.
The practical design of low-cost space structures involves the use of approaches that reduce the cost of the design and development effort itself. Such approaches include: (1) design with criteria arrived at rationally; (2) design for simplicity, repeatability, and modularity; (3) assembly without adjustments; (4) design for testability on the ground; (5) the attainment of structural efficiency by configuration and material choice rather than by squeezing down on the design margins; and (6) prefabrication and preassembly before launch. Attention is given to truss platform designs, and the Seasat Extendible Support Structure is discussed as a particular example.
The paper examines a construction capability to build large structures in space, its use in conjunction with the Shuttle Orbiter and a large Space Construction Base, and its relationship to system performance and cost. The geodetic beam design using a tetrahedral truss structure and reinforced plastics and its structural analysis, tests of demonstration cylinders, and preliminary machine design are discussed. The geodetic structure is shown to have high buckling stability, low thermal distortion, high stiffness, and its simple shape permits high-production-rate automatic fabrication. The geodetic beam fabrication machine which will automatically fabricate cylindrical beams in space from earth-prefabricated rods, and on-orbit beam and platform fabrication are described. Preliminary results of system performance and cost studies indicate that on-orbit fabrication using a small geodetic beam machine can be economically superior to the deployable and erectable modes of construction for many near term applications.
Sixteen conceptual designs of residential photovoltaic arrays are described. Each design concept was evaluated by an industry advisory panel using a comprehensive set of technical, economic and institutional criteria. Key electrical and mechanical concerns that effect further array subsystem development are also discussed. Three integrated array design concepts were selected by the advisory panel for further optimization and development. From these concepts a single one will be selected for detailed analysis and prototype fabrication. The three concepts selected are: (1) An array of frameless panels/modules sealed in a T shaped zipper locking neoprene gasket grid pressure fitted into an extruded aluminum channel grid fastened across the rafters. (2) An array of frameless modules pressure fitted in a series of zipper locking EPDM rubber extrusions adhesively bonded to the roof. Series string voltage is developed using a set of integral tongue connectors and positioning blocks. (3) An array of frameless modules sealed by a silicone adhesive in a prefabricated grid of rigid tape and sheet metal attached to the roof.
A large scale integration (LSI) technology, the standard transistor array uses a prefabricated understructure of transistors and a comprehensive library of digital logic cells to allow efficient fabrication of semicustom digital LSI circuits. The cell placement technique for this technology involves formation of a one dimensional cell layout and "folding" of the one dimensional placement onto the chip. It was found that, by use of various folding methods, high quality chip layouts can be achieved. Methods developed to measure of the "goodness" of the generated placements include efficient means for estimating channel usage requirements and for via counting. The placement and rating techniques were incorporated into a placement program (CAPSTAR). By means of repetitive use of the folding methods and simple placement improvement strategies, this program provides near optimum placements in a reasonable amount of time. The program was tested on several typical LSI circuits to provide performance comparisons both with respect to input parameters and with respect to the performance of other placement techniques. The results of this testing indicate that near optimum placements can be achieved by use of the procedures incurring severe time penalties.
The Extendable Tetrahedral Truss orbiting antenna concept, comprising the use of prefabricated, automatically deployable lattice structures and their subsequent assembly into larger structures suitable for microwave antenna use, is described. It is assumed that the Space Shuttle Orbiter payload bay will be able to accommodate only modular portions of the structural system required, and that the Space Shuttle crew will furnish the manual labor entailed by orbital assembly. It is concluded that a deployable beam module system may be a more elegant design solution than the alternative triangular-module system.
Although hardware description languages (HDL) are becoming more and more necessary to automated design systems, their application is complicated due to the difficulty in translating the HDL description into an implementable format, nonfamiliarity of hardware designers with high-level language programming, nonuniform design methodologies and the time and costs involved in transfering HDL design software. Digital design language (DDL) suffers from all of the above problems and in addition can only by synthesized on a complete system and not on its subparts, making it unsuitable for synthesis using standard modules or prefabricated chips such as those required in LSI or VLSI circuits. The present paper presents a method by which the DDL translator can be made to generate modular equations that will allow the system to be synthesized as an interconnection of lower-level modules. The method involves the introduction of a new language construct called a Module which provides for the separate translation of all equations bounded by it.
Study of concepts for large space structures will interest those designing scaffolding, radio towers, rescue equipment, and prefabricated shelters. Double-fold, double-cell module was selected for further design and for zero gravity testing. Concept is viable for deployment by humans outside space vehicle as well as by remotely operated manipulator.
The use of low cost, off the shelf prefabricated enclosures for spacecraft system thermal cycling applications was indicated. The enclosures are erected in the satellite integration areas without disturbing the test article, electrical test set, or RF interfaces. They are assembled by metal clad, modular urethane panels. These panels are self supporting, and are locked and sealed to each other on assembly. Penetrations for interconnecting cables, coaxial and waveguide services; and temperature conditioning inlet and outlet ducts are easily incorporated where required. The facility and its advantages and intrinsic benefits are described.
Strong supporting structures for flat solar photovoltaic arrays built with such commonly available materials as wood and galvanized steel sheet. Structures resist expected static loads from snow and ice as well as dynamic loads from winds and even Earthquake vibrations. Supporting structure uses inexpensive materials. Parts prefabricated to minimize assembly work in field.
Experimental results are presented that show that the structure of carbon fibers induces molecular orientation of liquid crystal polymers. X-ray diffraction data are used to demonstrate final collinearity of the polymer molecular axis and carbon fiber axis independent of fabrication approaches or prefabrication orientation of the polymer relative to the carbon fiber direction. The final degree of polymer molecular orientation approximately equals the degree of carbon basal plane orientation within the carbon fiber.
The Initial Manned Lunar Outpost (IMLO) is proposed as the initial permanent base for manned activities on the Moon. The study concentrated on identifying the equipment, support systems, and initial base configuration necessary to accomplish the various science, industrial and exploration activities planned. The primary concepts of the MLO were the use of hard modules for habitation areas creating a flexible, modular transportation system; designing a multi-functional vehicle; and using an overhead radiation protection system. The transportation system, dubbed the Lunar Mobile Surface Transport System (LMSTS), carries the hard modules to the surface of the moon and provides a method to move them to the desired location through the use of interchangeable pallets. The avionics pallets are changed-out with wheel and hitch pallets, transforming the LMSTS into a "tractor trailer" used with the Multi-Functional Vehicle (MFV). The modules are placed under the Regolith Support Structure (RSS) which provides a stable environment and radiation protection for the entire base. The overhead structure was chosen over simply burying the modules to provide a study on the advantages and disadvantages of this type of system. The advantages include easy access to the exterior of the modules, providing a protected area for vehicles and equipment used in EVA, and creating an area of constant temperature. Disadvantages include a need for prefabrication of structural components, including the preconstruction and construction phases of the initial MLO. The design approach taken considered existing and near-term materials and technology only, without the consideration of possible future building technologies.
Proposed welding technique combines best features of metal (other than tungsten)/inert-gas welding, plasma arc welding, and tungsten/inert-gas welding. Advantages include: wire fed to weld joint preheated, therefore fed at high speed without spattering; high-frequency energy does not have to be supplied to workpiece to initiate welding; size of arc gap not critical, power-supply control circuit adjusts voltage across gap to compensate for changes; only low gas-flow rate needed; welding electrode replaced easily as prefabricated assembly; external wire-feeding manipulator not needed; and welding process relatively forgiving of operator error.