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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 1,189 records · Page 66
All sourcesNASA NTRSDOE OSTI
NASA NTRS1978

Field effect transistor and method of construction thereof

A field effect transistor is constructed by placing a semi-conductor layer on an insulating substrate so that the gate region is separated from source and drain regions. The gate electrode and gate region of the layer are of generally reduced length, the gate region being of greatest length on its surface closest to the gate electrode. This is accomplished by initially creating a relatively large gate region of one polarity, and then reversing the polarity of a central portion of this gate region by ion bombardment, thus achieving a narrower final gate region of the stated configuration.

Fletner, W. R.↗
NASA NTRS1977

Lunar materials for construction of space manufacturing facilities

Development of industrial operations in deep space would be prohibitively expensive if most of the construction and expendable masses had to be transported from earth. Use of lunar materials reduces the needed investments by a factor of 15 to 20. It is shown in this paper that judicious selection of lunar materials will allow one to obtain hydrogen, nitrogen, carbon, helium and other specific elements critical to the support of life in large space habitats at relatively low costs and lower total investment even further. Necessary selection techniques and extraction schemes are outlined. In addition, tables are presented of the oxide and elemental abundances characteristic of the mare and highland regions of the moon which should be useful in evaluating what can be extracted from the lunar soils.

Criswell, D. R.↗
NASA NTRS1979

An Exploratory Investigation of the Effect of Plastic Coating on the Profile Drag of a Practical-Metal-Construction Sailplane Airfoil

An exploratory investigation was performed in the Langley low-turbulence pressure tunnel to determine the effect of a plastic coating on the profile drage of a practical-metal-construction sailplaine airfoil. The mode was tested with three surface configurations: (1) filled, painted, and sanded smooth; (2) rough bare metal; and (3) plastic-coated. The investigation was conducted at Reynolds numbers based on airfoil chord of 1,100,000, 2,200,000, and 3,300,000 at a constant Mach number of 0.10. The results indicate that, at all three Reynolds numbers, the order of the drag values of the three surface configurations, starting with the highest drag, was: filled, painted, and sanded smooth; rough bare metal; and plastic-coated.

Somers, D. M.↗
NASA NTRS1979

Method of construction of a multi-cell solar array

The method of constructing a high voltage, low power, multicell solar array is described. A solar cell base region is formed in a substrate such as but not limited to silicon or sapphire. A protective coating is applied on the base and a patterned etching of the coating and base forms discrete base regions. A semiconductive junction and upper active region are formed in each base region, and defined by photolithography. Thus, discrete cells which are interconnected by metallic electrodes are formed.

Routh, D. E.↗
NASA NTRS1979

An exploratory investigation of the effect of a plastic coating on the profile drag of a practical-metal-construction sailplane airfoil

The Langley low-turbulence pressure tunnel to determine the effect of a plastic coating on the profile drag of a practical-metal-construction sailplane airfoil was investigated. The model was tested with three surface configurations: (1) filled, painted, and sanded smooth; (2) rough bare metal; and (3) plastic-coated. The results are compared with data for the design airfoil (Wortmann FX 67-K-170/17) from another low-turbulence wind tunnel. The investigation was conducted at Reynolds numbers based on airfoil chord of 1.1 x 10 to the 6th power, 2.2 x 10 to the 6th power, and 3.3 x 10 to the 6th power at a Mach number of 0.10.

Somers, D. M.↗
NASA NTRS1979

Space Construction System Analysis. Special Emphasis Studies

Generic concepts were analyzed to determine: (1) the maximum size of a deployable solar array which might be packaged into a single orbit payload bay; (2) the optimal overall shape of a large erectable structure for large satellite projects; (3) the optimization of electronic communication with emphasis on the number of antennas and their diameters; and (4) the number of beams, traffic growth, and projections and frequencies were found feasible to package a deployable solar array which could generate over 250 kilowatts of electrical power. Also, it was found that the linear-shaped erectable structure is better for ease of construction and installation of systems, and compares favorably on several other counts. The study of electronic communication technology indicated that proliferation of individual satellites will crowd the spectrum by the early 1990's, so that there will be a strong tendency toward a small number of communications platforms over the continental U.S.A. with many antennas and multiple spot beams.

Source record↗
NASA NTRS1979

Fire-resistant materials for aircraft passenger seat construction

The thermal response characteristics of fabric and fabric-foam assemblies are described. The various aspects of the ignition behavior of contemporary aircraft passenger seat upholstery fabric materials relative to fabric materials made from thermally stable polymers are evaluated. The role of the polymeric foam backing on the thermal response of the fabric-foam assembly is also ascertained. The optimum utilization of improved fire-resistant fabric and foam materials in the construction of aircraft passenger seats is suggested.

Fewell, L. L.↗
NASA NTRS1979

The use of wood for wind turbine blade construction

The interrelationships between moisture and wood, conditions for dry rot spore activity, the protection of wood fibers from moisture, wood resin composites, wood laminating, quality control, and the mechanical properties of wood are discussed. The laminated veneer and the bonded sawn stock fabrication techniques, used in the construction of a turbine blade with a monocoque 'D' section forming the leading edge and a built up trailing edge section, are described. A 20 foot root end sample complete with 24 bonded-in studs was successfully subjected to large onetime loads in both the flatwise and edgewise directions, and to fatigue tests. Results indicate that wood is both a viable and advantageous material for use in wind turbine blades. The basic material is reasonably priced, domestically available, ecologically sound, and easily fabricated with low energy consumption.

Gougeon, M.↗
NASA NTRS1980

Development of a composite geodetic structure for space construction, phase 1A

The development of a geodetic beam and beam builder for on orbit construction of large truss type space structures is discussed. The geodetic beam is a lightweight, open lattice structure composed of an equilateral gridwork of crisscrossing rods. The beam provides a high degree of stiffness and minimizes structural distortion, due to temperature gradients, through the incorporation of a new graphite and glass reinforced thermoplastic composite material with a low coefficient of thermal expansion. A low power consuming, high production rate, beam builder automatically fabricates the geodetic beams in space using rods preprocessed on Earth. Three areas of the development are focused upon; (1) geodetic beam designs for local attachment of equipment or beam to beam joining in a parallel or crossing configurations, (2) evaluation of long life pultruded rods capable of service temperatures higher than possible with the HMS/P1700 rod material, and (3) evalaution of high temperature joint encapsulant materials.

Source record↗
NASA NTRS1979

Certain questions of the acclimatization of construction workers to the conditions of a subtropical climate

The period of active acclimatization was determined for construction workers coming into a subtropical climate. Changes were observed in metabolic processes, oxygen needs, pulse rate, arterial pressure, body and skin temperature, body weight, water consumption and loss, and the comfort zone of heat sensitivity. It was concluded that acclimatization is facilitated if introduction to the hot climate occurs in the mild cool season, rather than the summer. This also prevents heat prostration and improves the development of adaptive mechanisms.

Babayev, A.↗
NASA NTRS1980

Studies on questions of design and construction of chain scraper conveyors

The basic behavior of mining crushed goods in chain scraper conveyors was examined using a special test stand. The characteristics resistance lines of the upper end-piece were determined for conveyor idle as a function of the determinative crushed good characteristics (granular structure, moisture content, type of goods) on the size of the conveyor load, on the conveyor construction and on the stopped time of the conveyor. Crushed goods with a narrow granular profile and sphere-like grains caused about 35% greater resistance than fine coal and raw coal with broad granular profile. For goods containing water more than 10% by weight, the solids friction retreated in favor of flow friction. The coefficient of resistance decreased considerably in the range of lower speeds and then increased with increasing conveyor speed. The conveyance of sandstone ore required about 280% greater specific drive than the conveyance of raw coal. Resistance coefficients for coal and raw coal showed no dependence on the design of the conveyor. Start-up of loaded conveyors after longer stop times was simulated and the specific break-loose force was determined.

Guder, H.↗
NASA NTRS1979

Construction and testing of the 2.5m mass driver

Presented are the designs used in the construction of the 2.5 m mass driver and the results of the initial testing program. The mass driver consists of equal length sections of acceleration and deceleration each containing 59 drive coils of 13.1 cm caliber. Intermediate energy storage is provided by sector capacitors which are recharged every half cycle by an external power source. The drive coils are individually energized through SCR's with timing supplied by position sensing optical detectors. The drive consists of two phases which operate in quadrature. The initial bucket to be propelled through the mass driver contains two coils of aluminum wire chilled to liquid nitrogen temperatures to momentarily sustain superconducting field intensities. Magnetic flight is generated by eddy current repulsion from six copper guide strips lining the mass driver. Nominal acceleration is 5000 m/sec per sec giving a maximum bucket velocity of 112 m/s.

Snow, W. R.↗
NASA NTRS1979

Multilevel modeling of the space construction base

A mathematical model representing a flexible space vehicle in terms of interconnected discrete masses is recast into hierarchical form to facilitate the application of multilevel control techniques. The model's state equations are temporarily decoupled by utilization of a set of coordination equations. A hierarchical form of the model is constructed with the set of coordination equations at the top of the hierarchy and the set of decoupled scalar state equations in the bottom level.

Chichester, F. D.↗
NASA NTRS1980

A plane-polar approach for far-field construction from near-field measurements

The planar configuration with a probe scanning a polar geometry is discussed with reference to its usefulness in the determination of a far field from near-field measurements. The accuracy of the method is verified numerically, using the concept of probe compensation as a vector deconvolution. Advantages of the Jacobi-Bessel series over the fast Fourier transforms for the plane-polar geometry are demonstrated. Finally, the far-field pattern of the Viking high gain antenna is constructed from the plane-polar near-field measured data and compared with the previously measured far-field pattern.

Rahmat-Samii, Y.↗
NASA NTRS1980

A three-dimensional turbulent compressible subsonic duct flow analysis for use with constructed coordinate systems

An approximate analysis, applicable to nonorthogonal coordinate systems having a curved centerline and planar transverse coordinate surfaces normal to the centerline, is presented for computation of three-dimensional subsonic flow in straight and curved diffusers. The formulation is intended to facilitate the use of constructed coordinates in circumstances where it is difficult to maintain smooth behavior in higher derivatives; the use of local Cartesian variables and fluxes leads to governing equations which require only first derivatives of the coordinate transformation. The analysis is applied to a particular family of duct and diffuser geometries having curved centerlines and superelliptic cross sections. Qualitative agreement with experimental measurements is observed with regard to streamwise vortices and distortion of the primary flow.

Levy, R.↗