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Results for “Manufacturing Techniques”

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 433 records · Page 24
All sourcesNASA NTRSDOE OSTI
NASA NTRS1980

Image Properties of an X-Ray Telescope of the Wolter-1 Type with Emphasis on Contrast Reduction by Diffuse Reflection

Theoretical and experimental results are presented on the geometrical-optic imaging properties of a Wolter-1 type paraboloid-hyperboloid X-ray telescope. Particular consideration is given to the effect of microroughness of the mirror on the imaging properties. Experiments were conducted in which scattering properties were determined as a function of wavelength, incidence angle, and roughness of the plane mirrors. Results indicate the need for optimization of mirror material and polishing technology as well as the development of improved mirror manufacturing techniques. The use of transmission gratings along with the Wolter-1 type telescope in spectroscopy applications is discussed.

Lenzen, R.↗
NASA NTRS1980

Investigation of electrical noise in selenium-immersed thermistor bolometers

The selenium immersed, thermistor bolometer, IR detector failed due to spurious and escalating electrical noise outburst as a function of time at elevated temperatures during routine ground based testing in a space simulated environment. Spectrographic analysis of failed bolometers revealed selenium pure zones in the insulating selenium arsenic (Se-As) glass film which surrounds the active sintered Mn, Ni, Co oxide flake. The selenium pure film was identified as a potentially serious failure mechanism. Significant changes were instituted in the manufacturing techniques along with more stringent process controls which eliminated the selenium pure film and successfully produced 22study bolometers.

Tarpley, J. L.↗
NASA NTRS1982

Pressure Switch Is a Low Cost Battery Indicator

Conventional pressure switch, fabricated by printed-circuit manufacturing techniques, can indicate when charge on battery departs from preset level. Membrane on switch is exposed to internal pressure of battery, which varies according to stored charge. When pressure varies from preset level, switch can turn on a light-emitting diode or similar indicator to warn user that battery is low.

Abita, J. L.↗
NASA NTRS1980

Accuracy potentials for large space antenna structures

The relationships among materials selection, truss design, and manufacturing techniques in the interest of surface accuracies for large space antennas are discussed. Among the antenna configurations considered are: tetrahedral truss, pretensioned truss, and geodesic dome and radial rib structures. Comparisons are made of the accuracy achievable by truss and dome structure types for a wide variety of diameters, focal lengths, and wavelength of radiated signal, taking into account such deforming influences as solar heating-caused thermal transients and thermal gradients.

Hedgepeth, J. M.↗
NASA NTRS1982

Analysis of solidification interface shape resulting from applied sinusoidal heating

Maintaining a flat solidification interface is important for forming desired crystal structures in certain types of metal casting processes. This has application in new manufacturing techniques for naturally strengthened composite components such as turbine blades. The solidification interface shape will adjust to be compatible with the spatial distribution of energy being transferred to it. The interface shape must be found that satisfies conditions of simultaneously being at the fusion temperature and having an imposed spatially varying heat flux. Specific results are obtained for the heat transfer from the liquid phase varying along the interface in a cosine fashion. Interface shapes are found as a function of the amplitude and wavelength of the imposed heat transfer variations, and the sensitivity of the interface shape to these variations is examined.

Siegel, R.↗
NASA NTRS1982

Accuracy potentials for large space antenna reflectors with passive structure

Analytical results indicate that a careful selection of materials and truss design, combined with accurate manufacturing techniques, can result in very accurate surfaces for large space antennas. The purpose of this paper is to examine these relationships for various types of structural configurations. Comparisons are made of the accuracy achievable by truss- and dome-type structures for a wide range of diameter and focal length of the antenna and wavelength of the radiated signal.

Hedgepeth, J. M.↗
NASA NTRS1981

Optimization of large area solar cells for low cost space application

The development of large-area solar cell manufacturing techniques for production of up to 10 kW/month of cells for use on the Shuttle Power Extension Package is detailed. Design goals for the cells were 14% efficiency at 135.3 mW/sq cm AM0 illumination for a 10 ohm-cm BSF/reflector cell, or 12.8% for a 2 ohm-cm BSR cell. Use of terrestrial cell technology to produce CVD SiO2 dielectric insulators for 3-in. ingot cells yielded satisfactory contact integrity. Fused silica coverings with thicknesses of 0.004 in. have allowed exploration of conventional and wraparound cell configurations due to inherent flexibilities of the frosted covers. One production run can now handle 108 3-in. wafers for the wraparound form or 216 in one-sided contact evaporations, with both processes taking 70 mins. Current contact grid designs for space use production permits average efficiencies of 12.8%.

Matthei, K. W.↗
NASA NTRS1983

General Aviation Turbine Engine (GATE) Overview

When all the technology studies were done and the accompanying market analyses were complete, the conclusion was that it is indeed possible to reduce the cost of turbine engines by a factor of 3 using low-cost manufacturing techniques and increased production rates. In the interest of reducing engine cost, some performance was sacrificed. Yet we ended up with about a 20 percent predicted improvement in SFC over current technology turboprops. However, even this level of improvement does not match the low SFC of reciprocating powerplants--particularly those advanced concepts described earlier. The 20 percent better SFC and much lower weight of a turboprop does mean that if such a powerplant were installed in a resized small airplane, one could save between 10 and 30 percent fuel relative to existing recip engines, depending on different mission and airplane combinations. The price of the aircraft would go down about 15 percent in the case of a high powered single, or 25 percent in the case of a normal size twin. The operating costs would decrease about 10 percent in the case of the single, and as much as 35 percent in the case of the twin.

Strack, W. C.↗
NASA NTRS1982

Fabrication of bonded graphite/polyimide structures for advanced aerospace applications

The tooling concepts and manufacturing techniques developed to produce subelements and full-scale bonded test articles for two of the NASA Composites for Advanced Transportation Systems are examined as part of the structural development of graphite/polyimide composite material systems for the Space Shuttle Orbiter and other space transportation systems. The subassembly and the assembly bonding of the test articles were accomplished using self-tooling and low-cost aluminum tooling concepts in order to eliminate the need for complex and expensive tools. Processing procedures and tooling approaches were developed which permit controlled pressure application on specific bonding planes. Two test articles were fabricated using these techniques, an acoustic panel and a quarter segment of the Space Shuttle aft body flap.

Frost, R. K.↗
NASA NTRS1984

Solar absorptance and thermal emittance of some common spacecraft thermal-control coatings

Solar absorptance and thermal emittance of spacecraft materials are critical parameters in determining spacecraft temperature control. Because thickness, surface preparation, coatings formulation, manufacturing techniques, etc. affect these parameters, it is usually necessary to measure the absorptance and emittance of materials before they are used. Absorptance and emittance data for many common types of thermal control coatings, are together with some sample spectral data curves of absorptance. In some cases for which ultraviolet and particle radiation data are available, the degraded absorptance and emittance values are also listed.

Henninger, J. H.↗
NASA NTRS1984

Unidirectional fibers and polyurethane elastomer matrix based composites synthesis and properties

A study of the properties and manufacturing techniques for long-fiber reinforced elastomeric composites for flexible and damping structural materials is presented. Attention is given to the usage of polyurethane in the matrix to obtain plastic elastomeric matrices and vitreous transition temperatures which vary from -80 C to 10 C, as well as assure good fiber adhesion. Various polyurethane formulations synthesized from diisocyanate prepolymers are examined in terms of mechanical and thermal properties. The principal reinforcing fiber selected is a unidirectional glass cloth.

Chakar, A.↗
NASA NTRS1985

Manufacturing and producibility technology

Activities of the manufacturing/producibility working group within the Advanced High-Pressure O2/H2 Technology Program are summarized. The objectives of the M/P working group are: to develop and evaluate process and manufacturing techniques for advanced propulsion hardware design and selected materials; and to optimize the producibility of (SSME) components and assemblies by improved performance, increased life, greater reliability, and/or reduced cost. The technologies being developed include: plasma arc, laser, and inertia welding; combustion chamber and turbine blade coatings; coating processes; high performance alloy electroforming; and process control technology.

Hankins, J. D.↗
NASA NTRS1985

Bearings working group

The service life of the Space Shuttle Main Engine (SSME) turbomachinery bearings was a predominant factor in engine durability and maintenance problems. Recent data has indicated that bearing life is about one order of magnitude lower than the goal of seven and one-half hours particularly those in the High Pressure Oxidizer Turbopump (HPOTP). Bearing technology, primarily cryogenic turbomachinery bearing technology, is expanded by exploring the life and performance effects of design changes; design concept changes; materials changes; manufacturing technique changes; and lubrication system changes. Each variation is assessed against the current bearing design in full scale cryogenic tests.

Source record↗
NASA NTRS1984

Graphite/epoxy composite stiffened panel fabrication development

This report describes the manufacturing development procedures used to fabricate a series of carbon/epoxy panels with integrally molded stiffeners. Panel size was started at 6 inches by 18 inches and one stiffener and increased to 30 inches by 60 inches and six integral stiffeners. Stiffener concepts were optimized for minimum weight (or mass) to carry stress levels from 1500 lbs/inch to 25,000 lbs/inch compression load. Designs were created and manufactured with a stiffener configuration of integrally molded hat, J, I, sine wave I, solid blade, and honeycomb blade shapes. Successful and unsuccessful detail methods of tooling, lay-up methods, and bagging methods are documented. Recommendations are made for the best state-of-the-art manufacturing technique developed for type of stiffener construction.

Palmer, R. J.↗
NASA NTRS1985

National space transportation systems planning

In the fall of 1984, the DOD and NASA had been asked to identify launch vehicle technologies which could be made available for use in 1995 to 2010. The results of the studies of the two groups were integrated, and a consumer report, dated December 1984, was forwarded to the President. Aspects of mission planning and analysis are discussed along with a combined mission model, future launch system requirements, a launch vehicle planning background, Shuttle derivative vehicle program options, payload modularization, launch vehicle technology implications, a new engine program for the mid-1990's. Future launch systems goals are to achieve an order of magnitude reduction in future launch cost and meet the lift requirements and launch rates. Attention is given to an advanced cryogenic engine, advanced LOX/hydrocarbon engine, advanced power systems, aerodynamics/flight mechanics, reentry/recovery systems, avionics/software, advanced manufacturing techniques, autonomous ground and mission operations, advanced structures/materials, and air breathing propulsion.

Lucas, W. R.↗
NASA NTRS1986

Lessons learned from the DC-10 carbon-epoxy rudder program

With the DC-10 carbon-epoxy rudder, the Douglas Aircraft Company achieved one of the greatest percentage weight savings associated with composite structures. Apart from minor damage from lightning strikes, the 15 rudders put into service have experienced virtually trouble-free operation for about a decade. This paper explains why a multirib, postbuckled skin design was used for the DC-10 composite rudder, how it was justified, and how it would have compared with more conventional sandwich design concepts. Special attention is devoted to the reasons why, for such postbuckled designs, it is better to allow the skin to wrinkle and unload itself than to reinforce it and make it resist buckling until some higher load level is attained. With minor changes in the manufacturing technique, this design concept is ideal for the control surfaces on many aircraft. The paper includes suggestions on how to make even better composite control surfaces in the future.

Hart-Smith, L. J.↗
NASA NTRS1988

Small gas turbine engine technology

Performance of small gas turbine engines in the 250 to 1,000 horsepower size range is significantly lower than that of large engines. Engines of this size are typically used in rotorcraft, commutercraft, general aviation, and cruise missile applications. Principal reasons for the lower efficiencies of a smaller engine are well known: component efficients are lower by as much as 8 to 10 percentage points because of size effects. Small engines are designed for lower cycle pressures and temperatures because of smaller blading and cooling limitations. The highly developed analytical and manufacturing techniques evolved for large engines are not directly transferrable to small engines. Thus, it was recognized that a focused effort addressing technologies for small engies was needed and could significantly impact their performance. Recently, in-house and contract studies were undertaken at the NASA Lewis Research Center to identify advanced engine cycle and component requirements for substantial performance improvement of small gas turbines for projected year 2000 applications. The results of both in-house research and contract studies are presented. In summary, projected fuel savings of 22 to 42 percent could be obtained. Accompanying direct operating cost reductions of 11 to 17 percent, depending on fuel cost, were also estimated. High payoff technologies are identified for all engine applications, and recent results of experimental research to evolve the high payoff technologies are described.

Niedzwiecki, Richard W.↗