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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 sources NASA NTRS DOE OSTI

NASA NTRS1975

Study of the application of hydrogen fuel to long-range subsonic transport aircraft. Volume 1: Summary

The feasibility of using liquid hydrogen as fuel in advanced designs of long range, subsonic transport aircraft is assessed. Both passenger and cargo type aircraft are investigated. Comparisons of physical, performance, and economic parameters of the LH2 fueled designs with conventionally fueled aircraft are presented. Design studies are conducted to determine appropriate characteristics for the hydrogen related systems required on board the aircraft. These studies included consideration of material, structural, and thermodynamic requirements of the cryogenic fuel tanks and fuel systems with the structural support and thermal protection systems.

Brewer, G. D.↗

NASA NTRS1979

Photovoltaic systems perspective

This paper summarizes the elements of photovoltaic power system and clarifies the terminology currently used. The relationship of system efficiency and cost is described particularly for the Balance of Photovoltaic System (BOPS) area. The current status of the BOPS development activity is described. The photovoltaic systems terminology is found to be on the road to standardization. Power conditioning, energy storage, and support structure are found to be BOPS cost and/or efficiency drivers. Although the current BOPS activity has identified low-cost/high-efficiency components, further development work is necessary.

Sutton, P. D.↗

NASA NTRS1979

A Microwave Radiometer Spacecraft, some control requirements and concepts

A general overview of a conceptual design for a Microwave Radiometer Spacecraft using a large passive reflector, microwave radiometers, and advanced control concepts is presented. The mission requirements, developed around high resolution, large area mapping of soil moisture for global crop forecasting, are reviewed. These mission requirements, along with system design requirements, dictate the need for a reflector in excess of 700 meters in diameter. Conceptual designs for supporting structures and subsystems, including attitude and surface control, are summarized.

Lovelace, U. M.↗

NASA NTRS1981

Solar-heated bank-Marks Mississippi

Report describes air solar-energy collectors which supply 60 percent of space heating load for full-service bank. Contemporary structure supports 468 square feet of flat-plate arrays, and features onsite temperature and power measurement readouts. Air-flow collectors minimize problems experienced with conventional liquid solar equipment and eliminate need for heat exchanger for space heating.

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NASA NTRS1980

Offset weap rib concept and development

The applicability of the Wrap rib antenna design for offset feed configurations for antennas up to 300 m in diameter was assessed. The antenna design was defined for both symmetric and offset configurations in terms of surface quality, cost, weight, and mechanical complexity. A supporting deployable feed support structure was developed and characterized.

Woods, A. A., Jr.↗

NASA NTRS1979

Study of wrap-rib antenna design

The results of a parametric design study conducted to develop the significant characteristics and technology limitations of space deployable antenna systems with aperture sizes ranging from 50 up to 300 m and F/D ratios between 0.5 and 3.0 are presented. Wrap/rib type reflectors of both the prime and offset fed geometry and associated feed support structures were considered. The significant constraints investigated as limitations on achievable aperture were inherent manufacturability, orbit dynamic and thermal stability, antenna weight, and antenna stowed volume. A data base, resulting in the defined maximum achievable aperture size as a function of diameter, frequency and estimated cost, was formed.

Wade, W. D.↗

NASA NTRS1979

Magnetic suspension system for an Annular Momentum Control Device (AMCD)

A technique to control a rim suspended in a magnetic field was developed. A complete system was developed, incorporating a support structure, magnetic actuators, a rim drive mechanism, an emergency fail-safe system, servo control system, and control electronics. Open loop and closed loop response of the system at zero speed and at 500 revolutions per minute (r/min) of the rim was obtained and analyzed. The rim was then dynamically balanced and a rim speed of 725 r/min was achieved. An analog simulation of the hardware was developed and tested with the actual control electronics connected to the analog computer. The system under development is stable at rim speeds below 700 r/min. Test results indicate that the rim under test is not rigid. The rim has a warp and a number of binding modes which prevented achievement of higher speeds. Further development efforts are required to achieve higher rim speeds.

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NASA NTRS1980

Parametric instabilities of rotor-support systems with application to industrial ventilators

Rotor support systems interaction with parametric excitation is considered for both unequal principal shaft stiffness (generators) and offset disc rotors (ventilators). Instability regions and types of instability are computed in the first case, and parametric resonances in the second case. Computed and experimental results are compared for laboratory machine models. A field case study of parametric vibrations in industrial ventilators is reported. Computed parametric resonances are confirmed in field measurements, and some industrial failures are explained. Also the dynamic influence and gyroscopic effect of supporting structures are shown and computed.

Parszewski, Z.↗

NASA NTRS1980

Low-pass interference filters for submillimeter astronomy

Low-pass (long-wave transmitting) interference filters, suitable for broadband photometric observations, previously have been constructed from series of capacitive grids stretched on thin Mylar. These filters have the desired optical properties of high transmission, sharp cut-ons, and good blocking at short wavelengths. Their designs, however, do not scale from one wavelength to another and their performance can deteriorate at low temperatures due to differential contraction of the dielectric backing and the supporting structure. The deviation of these early filters from the predicted scaling was due primarily to the difference in refractive index between the backing material and the medium between the grids. In the present paper, filters are described in which dielectric spacers are used, instead of air, as the medium between the grids. This technique has improved the scaling and has reduced the distortion from differential contraction.

Whitcomb, S. E.↗

NASA NTRS1980

The large-scale far-infrared structure of W3 and W4

The large-scale structure of the giant H II region complex W3/W4 has been mapped in two wavelength bands covering 60 to 120 microns at an angular resolution of 12 arc min. The only region of strong emission observed lies along a molecular ridge at an ionization/shock front in the sources. This structure supports the idea that a new generation of stars formed after neutral material ahead of the front became gravitationally unstable. These embedded stars are dominating the energetics of the molecular/infrared cloud, although the visible OCl 352 cluster in neighboring IC 1805 may supply much of the heating flux to the fainter regions. A simple model relating the far-infrared and CO emission is presented.

Thronson, H. A., Jr.↗

NASA NTRS1979

Development of CO2 laser Doppler instrumentation for detection of clear air turbulence, volume 2: Appendices

Analyses of the mounting and mount support systems of the clear air turbulence transmitters verify that satisfactory shock and vibration isolation are attained. The mount support structure conforms to flight crash safety requirements with high margins of safety. Restraint cables reinforce the mounts in the critical loaded forward direction limiting maximum forward system deflection to 1 1/4 inches.

Harris, C. E.↗

NASA NTRS1980

Shuttle remote manipulator system hardware test facility

The shuttle remote manipulator (RMS) is designed and built for operations in a zero gravity environment. As such, the ground test facility for the integrated RMS must simulate conditions which support verification of the overall system performance. In order to allow ground test operations, a test facility was constructed with an area of 60 ft. x 120 ft. and extremely tight tolerances on floor flatness and slope. An air bearing support structure was designed for the RMS to operate with 4 degrees of freedom. The RMS system test facility and systems tests conducted to date are described.

Wagner-Bartak, C. G.↗

NASA NTRS1980

Safety of liquid propulsion systems for STS payloads

STS payload safety requirements for Earth-storable liquid propulsion systems are reviewed with respect to applicable safety documents. The effect of normal flight and emergency landing/abort launch profiles on propulsion system design is delineated. Spacecraft studied include Earth satellites, interplanetary spacecraft, and orbit transfer vehicles. Safety considerations for monopropellant (hydrazine), bipropellant (nitrogen tetroxide/monomethyl hydrazine), and ion (mercury) propulsion systems are described. Safety requirements for specific components of propulsion systems are reported. Analysis techniques for STS payload fracture control requirements for pressure vessels and critical support structure are discussed.

Lewis, J. C.↗

NASA NTRS1981

Comments on settling chamber design for quiet, blowdown wind tunnels

Transfer of an existing continous circuit supersonic wind tunnel to Langley and its operation there as a blowdown tunnel is planned. Flow disturbance requirements in the supply section and methods for reducing the high level broad band acoustic disturbances present in typical blowdown tunnels are reviewed. Based on recent data and the analysis of two blowdown facilities at Langley, methods for reducing the total turbulence levels in the settling chamber, including both acoustic and vorticity modes, to less than one percent are recommended. The pertinent design details of the damping screens and honeycomb and the recommended minimum pressure drop across the porous components providing the required two orders of magnitude attenuation of acoustic noise levels are given. A suggestion for the support structure of these high pressure drop porous components is offered.

Beckwith, I. E.↗

NASA NTRS1977

Space Fabrication Demonstration System

Progress on fabrication facility (beam builder) support structure control, clamp/weld block, and welding and truss cut off is discussed. The brace attachment design was changed and the design of the weld mechanism was modified which achieved the following system benefits: (1) simplified weld electrode life; (2) reduced weld power requirements; and (3) simplified brace attachment mechanisms. Static and fatigue characteristics of spot welded 2024T3 aluminum joints are evaluated.

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NASA NTRS1981

Advanced solar concentrator: Preliminary and detailed design

A single reflection point focusing two-axis tracking paraboloidal dish with a reflector aperture diameter of approximately 11 m has a reflective surface made up of 64 independent, optical quality gores. Each gore is a composite of a thin backsilvered mirror glass face sheet continuously bonded to a contoured substrate of lightweight, rigid cellular glass. The use of largely self-supporting gores allows a significant reduction in the weight of the steel support structure as compared to alternate design concepts. Primary emphasis in the preliminary design package for the low-cost, low-weight, mass producible concentrator was placed on the design of the higher cost subsystems. The outer gore element was sufficiently designed to allow fabrication of prototype gores.

Bell, D. M.↗

NASA NTRS1981

Investigation of potential of differential absorption Lidar techniques for remote sensing of atmospheric pollutants

The NASA multipurpose differential absorption lidar (DIAL) system uses two high conversion efficiency dye lasers which are optically pumped by two frequency-doubled Nd:YAG lasers mounted rigidly on a supporting structure that also contains the transmitter, receiver, and data system. The DIAL system hardware design and data acquisition system are described. Timing diagrams, logic diagrams, and schematics, and the theory of operation of the control electronics are presented. Success in obtaining remote measurements of ozone profiles with an airborne systems is reported and results are analyzed.

Butler, C. F.↗

NASA NTRS1981

Image motion compensation on the Spacelab 2 Solar Optical Universal Polarimeter /SL2 SOUP/

The SOUP experiment on Spacelab 2 includes a 30 cm visible light telescope and focal plane package mounted on the Instrument Pointing System (IPS). Scientific goals of the experiment dictate pointing stability requirements of less than 0.05 arcsecond jitter over periods of 5-20 seconds. Quantitative derivations of these requirements from two different aspects are presented: (1) avoidance of motion blurring of diffraction-limited images; (2) precise coalignment of consecutive frames to allow measurement of small image differences. To achieve this stability, a fine guider system capable of removing residual jitter of the IPS and image motions generated on the IPS cruciform instrument support structure has been constructed. This system uses solar limb detectors in the prime focal plane to derive an error signal. Image motion due to pointing errors is compensated by the agile secondary mirror mounted on piezoelectric transducers, controlled by a closed-loop servo system.

Tarbell, T. D.↗