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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 775 records · Page 43
All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

Coherent Optical Processing of Phased Array Radar Data

Interfacing a coherent optical processor, which utilizes an electron-beam addressed, potassium dideuterium phosphate (KDP) crystal modulator, with a linear phased array is studied. An abbreviated development of typical radar signals from a linear array is included. A plan for formating the spatial modulator with linear array signals is presented. The theoretical expectations which include target angle and Doppler are derived. A simulated set of M signals which are typical of a linear array of M elements was devised. This set of signals was used to modulate the wave front of collimated laser light via the KDP crystal according to the format presented.

Rogers, J. W.↗
NASA NTRS1972

Feasibility study of a 110 watt per kilogram lightweight solar array system

An investigation of the feasibility of a solar array panel subsystem which will produce 10,000 watts of electrical output at 1 A.U. with an overall beginning-of-life power-to-weight ratio of at least 110 watt/kg is reported. A description of the current baseline configuration which meets these requirements is presented. A parametric analysis of the single boom, two blanket planar solar array system was performed to arrive at the optimum system aspect ratio. A novel concept for the stiffening of a lightweight solar array by canting the solar cell blankets at a small angle to take advantage of the inherent in-plane stiffness to increase the symmetric out-of-plane frequency is introduced along with a preliminary analysis of the stiffening effect. A comparison of welded and soldered solar cell interconnections leads to the conclusion that welding is required on this ultralightweight solar array. The use of a boron/aluminum composite material in a BI-STEM type deployable boom is investigated as a possible advancement in the state-of-the-art.

Shepard, N. F.↗
NASA NTRS1972

Design and development of a brushless, direct drive solar array reorientation system

This report covers the design and development of the laboratory model, and is essentially a compilation of reports covering the system and its various parts. To enhance completeness, the final report of Phase 1 covering circuit development of the controller is also included. A controller was developed for a brushless, direct-drive, single axis solar array reorientation system for earth-pointed, passively-stabilized spacecraft. A control systems was designed and breadboard circuits were built and tested for performance. The controller is designed to take over automatic control of the array on command after the spacecraft is stabilized in orbit. The controller will orient the solar array to the sun vector and automatically track to maintain proper orientation. So long as the orbit is circular, orientation toward the sun is maintained even though the spacecraft goes into the shadow of the earth. Particular attention was given in the design to limit reaction between the array and the spacecraft.

Jessee, R. D.↗
NASA NTRS1972

Passive solar array orientation devices for terrestrial application.

A passive solar array orientation device, called a thermal heliotrope, is described, and several terrestrial applications are illustrated. The thermal heliotrope consists of a bimetallic helical coil that serves as the motor element, producing torque and angular displacement. A control mechanism in the form of one or more shades completes the basic device. In comparison with electromechanical tracking systems, the thermal heliotrope is electrically passive, has relatively few parts, and is low cost. After describing the principle of operation and several models built for space applications, the design considerations for several terrestrial thermal heliotrope units are presented. It is suggested that the use of the thermal heliotrope for solar array orientation could significantly reduce array cost, thereby increasing the competitive economic posture of solar arrays for terrestrial applications. The thermal heliotrope modified for terrestrial use is readily adaptable to orient solar energy concentrators, such as furnaces and stills.

Fairbanks, J. W.↗
NASA NTRS1972

Solar array cost reductions.

There is great interest in reducing the cost of solar arrays, which will continue to be the prime power source for unmanned spacecraft for some time. The cost of solar power systems over the last decade, and means by which cost reductions may be achieved in the future are discussed. It is shown that the total system cost index is a function of solar array area, and that cost decreases as production of solar arrays goes up. This effect can be exploited more than has been done in the past by making common building blocks from which a variety of arrays can be assembled.

Bernatowicz, D. T.↗
NASA NTRS1974

A four-element end-fire microphone array for acoustic measurements in wind tunnels

A prototype four-element end-fire microphone array was designed and built for evaluation as a directional acoustic receiver for use in large wind tunnels. The microphone signals were digitized, time delayed, summed, and reconverted to analog form in such a way as to create a directional response with the main lobe along the array axis. The measured array directivity agrees with theoretical predictions confirming the circuit design of the electronic control module. The array with 0.15 m (0.5 ft) microphone spacing rejected reverberations and background noise in the Ames 40- by 80-foot wind tunnel by 5 to 12 db for frequencies above 400 Hz.

Soderman, P. T.↗
NASA NTRS1974

Analysis of finite-size phased arrays of circular waveguide elements

A derivation is presented for the calculation of the interelement mutual coupling in a finite-size planar array of waveguide-fed apertures covered by a multilayered dielectric and/or plasma. The general mutual admittance expression is evaluated for circular apertures and the mutual coupling calculations are verified experimentally for two transverse electric circular waveguide mode excited apertures. A parametric study of higher order mode aperture fields indicates that the only significant change in the circular aperture mutual coupling is due to the transverse magnetic mode, which introduces an additional phase shift. Qualitative agreement between calculations for a 183-element array of circular apertures and an infinite array establishes the validity of the finite-array theoretical model.

Bailey, M. C.↗
NASA NTRS1974

The data array, a tool to interface the user to a large data base

Aspects of the processing of spacecraft data is considered. Use of the data array in a large address space as an intermediate form in data processing for a large scientific data base is advocated. Techniques for efficient indexing in data arrays are reviewed and the data array method for mapping an arbitrary structure onto linear address space is shown. A compromise between the two forms is given. The impact of the data array on the user interface are considered along with implementation.

Foster, G. H.↗
NASA NTRS1973

The performance of solar arrays in deep space

Spacecraft of the Mariner class have been used by the United States during the past 11 years for planetary exploration. During these missions, the solar array performance characteristics were carefully monitored, and the data were reduced and analyzed. In addition to the direct array telemetry itself, the five latest Mariners were also equipped with a special transducer to aid in evaluating performance and determining the cause of array degradation. This paper describes the performance results of the Mariner solar arrays and the intelligence returned from the special performance transducer carrier on the later flights.

Goldsmith, J. V.↗
NASA NTRS1974

Mutual coupling in a finite planar array of circular apertures

Equations are presented for the calculation of the interelement mutual coupling in a finite-size planar array of waveguide-fed apertures in an infinite flat conductor. The general mutual admittance expression is evaluated for circular apertures, and the mutual coupling calculations are verified experimentally for two Te-(11) mode excited apertures. Qualitative agreement between calculations for a 183-element array and an infinite array establishes the validity of the finite-array theoretical model.

Bailey, M. C.↗
NASA NTRS1974

Mutual coupling in a finite planar array of circular apertures

Equations are presented for the calculation of the interelement mutual coupling in a finite size planar array of wave-guide-fed apertures in an infinite flat conductor. The general mutual admittance expression is evaluated for circular apertures and the mutual coupling calculations are verified experimentally for two TE11 mode excited apertures. Qualitative agreement between calculations for a 183 element array and an infinite array establishes the validity of the finite array theoretical model.

Bailey, M. C.↗
NASA NTRS1975

An experimental investigation of heat transfer to reusable surface insulation tile array gaps in a turbulent boundary layer with pressure gradient

An experimental investigation was performed to determine the effect of pressure gradient on the heat transfer to space shuttle reusable surface insulation (RSI) tile array gaps under thick, turbulent boundary layer conditions. Heat transfer and pressure measurements were obtained on a curved array of full-scale simulated RSI tiles in a tunnel wall boundary layer at a nominal freestream Mach number of 10.3 and freestream unit Reynolds numbers of 1.6, 3.3, and and 6.1 million per meter. Transverse pressure gradients were induced over the model surface by rotating the curved array with respect to the flow. Definition of the tunnel wall boundary layer flow was obtained by measurement of boundary layer pitot pressure profiles, and flat plate wall pressure and heat transfer. Flat plate wall heat transfer data were correlated and a method was derived for prediction of smooth, curved array heat transfer in the highly three-dimensional tunnel wall boundary layer flow and simulation of full-scale space shuttle vehicle pressure gradient levels was assessed.

Throckmorton, D. A.↗
NASA NTRS1974

Test report SEPS solar array root section model

The fabrication and test of a solar array functional root section model to verify preliminary array design concepts is presented. The root section model is full scale width and contains a model array blanket. The blanket contains 1/8 live electrical modules and the remainder contains solar cell mass simulators. A storable Astromast is used for array blanket extension and retraction. The model component and system assembly hardware, tests, and test results are described.

Source record↗
NASA NTRS1975

Cost competitiveness of a solar cell array power source for ATS-6 educational TV terminal

A cost comparison is made between a terrestrial solar cell array power system and a variety of other power sources for the ATS-6 Satellite Instructional Television Experiment (SITE) TV terminals in India. The solar array system was sized for a typical Indian location, Lahore. Based on present capital and fuel costs, the solar cell array power system is a close competitor to the least expensive alternate power system. A feasibility demonstration of a terrestrial solar cell array system powering an ATS-6 receiver terminal at Cleveland, Ohio is described.

Masters, R. M.↗
NASA NTRS1975

Airborne electronically steerable phased array

Results of a study directed to the design of a lightweight high-gain, spaceborne communications array are presented. The array includes simultaneous transmission and receiving, automatic acquisition and tracking of a signal within a 60-degree cone from the array normal, and provides for independent forming of the transmit and receive beams. Application for this array is the space shuttle, space station, or any of the advanced manned (or unmanned) orbital vehicles. Performance specifications are also given.

Coats, R.↗
NASA NTRS1975

Pressure gradient effects on heat transfer to reusable surface insulation tile-array gaps

An experimental investigation was performed to determine the effect of pressure gradient on the heat transfer within space shuttle reusable surface insulation (RSI) tile-array gaps under thick, turbulent boundary-layer conditions. Heat-transfer and pressure measurements were obtained on a curved array of full-scale simulated RSI tiles in a tunnel-wall boundary layer at a nominal free-stream Mach number and free-stream Reynolds numbers. Transverse pressure gradients of varying degree were induced over the model surface by rotating the curved array with respect to the flow. Definition of the tunnel-wall boundary-layer flow was obtained by measurement of boundary-layer pitot pressure profiles, wall pressure, and heat transfer. Flat-plate heat-transfer data were correlated and a method was derived for prediction of heat transfer to a smooth curved surface in the highly three-dimensional tunnel-wall boundary-layer flow. Pressure on the floor of the RSI tile-array gap followed the trends of the external surface pressure. Heat transfer to the surface immediately downstream of a transverse gap is higher than that for a smooth surface at the same location. Heating to the wall of a transverse gap, and immediately downstream of it, at its intersection with a longitudinal gap is significantly greater than that for the simple transverse gap.

Throckmorton, D. A.↗
NASA NTRS1975

Geometric analysis and restitution of digital multispectral scanner data arrays

An investigation was conducted to define causes of geometric defects within digital multispectral scanner (MSS) data arrays, to analyze the resulting geometric errors, and to investigate restitution methods to correct or reduce these errors. Geometric transformation relationships for scanned data, from which collinearity equations may be derived, served as the basis of parametric methods of analysis and restitution of MSS digital data arrays. The linearization of these collinearity equations is presented. Algorithms considered for use in analysis and restitution included the MSS collinearity equations, piecewise polynomials based on linearized collinearity equations, and nonparametric algorithms. A proposed system for geometric analysis and restitution of MSS digital data arrays was used to evaluate these algorithms, utilizing actual MSS data arrays. It was shown that collinearity equations and nonparametric algorithms both yield acceptable results, but nonparametric algorithms possess definite advantages in computational efficiency. Piecewise polynomials were found to yield inferior results.

Baker, J. R.↗
NASA NTRS1975

Silicon solid/state linear arrays for multispectral high resolution imaging systems

Solid-state, electronically scanned, linear detector arrays are now available which can be used in a pushbroom scan mode imaging system for high-resolution multispectral earth resource survey applications. These arrays provide high performance in the visible to near-IR region. Two performance criteria must be assessed in the choice of a detector array: signal-to-noise ratio and spectral response. Consideration of diffraction limitations shows that optics size cannot be significantly reduced by using very low-noise detectors. The required spectral response for a viable detector array should not have spectral ripples that cause a low-level, but significant, error in the detected effective reflectance of the target.

Thompson, L. L.↗