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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 199 records · Page 11
All sourcesNASA NTRSDOE OSTI
NASA NTRS1983

Radiant heating tests of several liquid metal heat-pipe sandwich panels

Integral heat pipe sandwich panels, which synergistically combine the thermal efficiency of heat pipes and the structural efficiency of honeycomb sandwich construction, were conceived as a means of alleviating thermal stress problems in the Langley Scramjet Engine. Test panels which utilized two different wickable honeycomb cores, facesheets with screen mesh sintered to the internal surfaces, and a liquid metal working fluid (either sodium or potassium) were tested by radiant heating at various heat load levels. The heat pipe panels reduced maximum temperature differences by 31 percent with sodium working fluid and 45 percent with potassium working fluid. Results indicate that a heat pipe sandwich panel is a potential, simple solution to the engine thermal stress problem. Other interesting applications of the concept include: cold plates for electronic component and circuit card cooling, radiators for large space platforms, low distortion large area structures (e.g., space antennas) and laser mirrors.

Camarda, C. J.↗
NASA NTRS1983

Inertial navigation/calibration/precise time and frequency capabilities

The Aerospace Guidance and Metrology Center was conceived in 1959 to be the US Air Force Inertial Navigation and Metrology Center. This paper will show the mission capabilities of the Inertial Navigation Maintenance Center and the Air Force Measurement and Standards Laboratory. Highlighted will be the precise time and frequency program developed by AGMC to support Air Force precise time and frequency requirements worldwide. A description of the past, present, and future precise time and frequency activities will be presented.

Galloway, L. M.↗
NASA NTRS1982

Hybrid thermoelectric solar collector design and analysis

A flat-plate solar collector is conceived where energy cascades through thermoelectric power modules generating direct-current electricity. The intent of this work was to choose a collector configuration and to perform a steady-state thermal performance assessment. A set of energy balance equations were written and solved numerically for the purpose of optimizing collector thermal and electrical performance. The collector design involves finned columns of thermoelectric modules imbedded in the absorber plate (hot junction) over a parallel array of vertical tubes. The thermoelectric power output is limited by the small hot-junction/cold-junction temperature difference which can be maintained under steady-state conditions. The electric power per unit tube pass area is found to have a maximum as a function of a geometric parameter, while electric power is maximized with respect to an electric resistance ratio. Although the electric power efficiency is small, results indicate that there is sufficient electric power production to drive a coolant circulator, suggesting the potential for a stand-alone system.

Roberts, A. S., Jr.↗
NASA NTRS1982

Simple phenomenological modeling of transition-region capacitance of forward-biased p-n junction diodes and transistor diodes

The derivation of a simple expression for the capacitance C(V) associated with the transition region of a p-n junction under a forward bias is derived by phenomenological reasoning. The treatment of C(V) is based on the conventional Shockley equations, and simpler expressions for C(V) result that are in general accord with the previous analytical and numerical results. C(V) consists of two components resulting from changes in majority carrier concentration and from free hole and electron accumulation in the space-charge region. The space-charge region is conceived as the intrinsic region of an n-i-p structure for a space-charge region markedly wider than the extrinsic Debye lengths at its edges. This region is excited in the sense that the forward bias creates hole and electron densities orders of magnitude larger than those in equilibrium. The recent Shirts-Gordon (1979) modeling of the space-charge region using a dielectric response function is contrasted with the more conventional Schottky-Shockley modeling.

Lindholm, F. A.↗
NASA NTRS1983

Radiant heating tests of several liquid metal heat-pipe sandwich panels

Integral heat-pipe sandwich panels, which synergistically combine the thermal efficiency of heat pipes and the structural efficiency of honeycomb sandwich construction, were conceived as a means of alleviating thermal stress problems in the Langley Scramjet Engine. Test panels which utilized two different wickable honeycomb cores, facesheets with screen mesh sintered to the internal surfaces, and a liquid metal working fluid (either sodium or potassium) were tested by radiant heating at various heat-load levels. The heat-pipe panels reduced maximum temperature differences by 31 percent with sodium working fluid and 45 percent with potassium working fluid. Results indicate that a heat-pipe sandwich panel is a potential, simple solution to the engine thermal stress problem. Other interesting applications of the concept include: cold plates for electronic component and circuit card cooling, radiators for large space platforms, low-distortion large area structures (e.g., space antennas) and laser mirrors.

Camarda, C. J.↗
NASA NTRS1982

AXAF, a permanent orbiting X-ray observatory - Telescope and instrumentation plans

The Advanced X-ray Astrophysics Facility (AXAF) now under study is to be a long-lived X-ray observatory in space. It is to be launched by the Space Shuttle, maintainable on-orbit, and retrievable for ground re-furbishment. The AXAF is conceived as an X-ray telescope with 6 nested grazing incidence X-ray mirrors (with a maximum aperture of 1.2 m) and interchangeable and replaceable focal plane instruments. The optics will provide 0.5 arcsecond imagery over a several arcminute field and somewhat reduced resolution over 1 degree in the X-ray band from 0.1 to 10 keV (1.2 to 120 A). The characteristics and expected performance of the observatory are described.

Zombeck, M. V.↗
NASA NTRS1982

AXAF, a permanent orbiting X-ray observatory - Telescope and instrumentation plans

The Advanced X-ray Astrophysics Facility (AXAF) now under study is to be a long-lived X-ray observatory in space. It is to be launched by the Space Shuttle, maintainable on-orbit, and retrievable for ground re-furbishment. The AXAF is conceived as an X-ray telescope with 6 nested grazing incidence X-ray mirrors (with a maximum aperture of 1.2 microns) and interchangeable and repleceable focal plane instruments. The optics will provide 0.5 arcsecond imagery over a several arcminute field and somewhat reduced resolution over 1 degree in the X-ray band from 0.1 to 10 keV (1.2 to 120 A). The characteristics and expected performance of the observatory are described.

Zombeck, M. V.↗
NASA NTRS1982

Computational fluid dynamics of airfoils and wings

It is pointed out that transonic flow is one of the fields where computational fluid dynamics turns out to be most effective. Codes for the design and analysis of supercritical airfoils and wings have become standard tools of the aircraft industry. The present investigation is concerned with mathematical models and theorems which account for some of the progress that has been made. The most successful aerodynamics codes are those for the analysis of flow at off-design conditions where weak shock waves appear. A major breakthrough was achieved by Murman and Cole (1971), who conceived of a retarded difference scheme which incorporates artificial viscosity to capture shocks in the supersonic zone. This concept has been used to develop codes for the analysis of transonic flow past a swept wing. Attention is given to the trailing edge and the boundary layer, entropy inequalities and wave drag, shockless airfoils, and the inverse swept wing code.

Garabedian, P.↗
NASA NTRS1982

Plans for a large deployable reflector for submillimeter and infrared astronomy from space

Continuing plans for a large deployable reflector (LDR), conceived as a 10- to 30-m-diameter clear-aperture telescope, operating at wavelengths from 1000 microns to a diffraction-limited 30 microns, and to be placed in orbit for a life of 10 years by the Space Shuttle, are discussed. The primary reflector will be composed of a number of closely packed hexagonal segments of glass or lightweight composite material and attached to a truss integrating structure through position actuators providing three degrees of freedom for each segment. Technical aspects of optical design, surface measurement systems, deployment, and detectors are discussed, as are practical and fiscal limitations.

Swanson, P. N.↗
NASA NTRS1982

A common-aperture X- and S-band four-function feedcone

Williams and Withington (1979) have considered a prototype X-S-band feedhorn which enabled simultaneous X- and S-band reception from a Cassegrain antenna. This feedhorn has quite successfully demonstrated an alternate method to the standard Deep Space Network (DSN) system of multiple subreflectors and dichroic plate for dual-band reception. In connection with a Network Consolidation Program, involving centralized control of existing antennas and construction of new reflector antennas, a second-generation feedhorn/combiner was conceived to show that this common-aperture feedhorn system was capable of performing all necessary functions the DSN would be called upon to perform with existing and future X-S-band spacecraft. Attention is given to the feedhorn concept, the combiner concept, the first and the second generation of the horn, Sand X-band tuning, and planned capabilities. The feedhorn greatly extends the state of the art in DSN performance and will enhance DSN capabilities in the future.

Withington, J. R.↗
NASA NTRS1983

Photolysis of methane and the ionosphere of Uranus

Photochemical calculations for Uranus predict an extensive region of condensation of acetylene, ethane and methane in the vicinity of the temperature inversion layer. This could explain why ethane was not detected on Uranus, unlike Neptune which has a much warmer inversion layer. Subsequent snow-out of the condensibles is expected to result in reduced visibility in the troposphere. Ionospheric calculations for the equatorial region to be probed by Voyager, indicate peak electron concentrations on the order of 5,000 per cu cm, if dynamical effects are important. Upper limit to the electron peak is 30,000 per cu cm. Exospheric temperatures as high as 200-250K are conceivable.

Atreya, S. K.↗
NASA NTRS1983

Production and analysis of output data products for Landsat-4 in the engineering check-out phase

The Landsat-D (now Landsat-4) program was initiated by NASA in the mid-1970's. The spacecraft was launched on July 16, 1982. Instruments on the satellite include the fourth Multispectral Scanner (MSS) and the new higher-resolution Thematic Mapper (TM). In order to achieve the planned engineering and scientific objectives, attention has to be given to the validation of spacecraft and instrument performance, the adjustment of ground processing procedures, and the definition of the measures of the TU utility. To satisfy these requirements, a Landsat Assessment System (LAS) was conceived, and the Applications Developmental Data System (ADDS) was instituted. The set of component systems collectively became known as the 'Scrounge' system. The present investigation is concerned with the Scrounge system and the results of radiometric and geometric data evaluations. Attention is given to the TM geometric correction, TM data resampling, a radiometric correction functional description, and the results of the TM geometric and radiometric correction.

Lyon, J. C.↗
NASA NTRS1983

Tracking and data relay satellite system (TDRSS) - A worldwide view from space

The development, performance levels, and operational use of the TDRSS satellite system are outlined. The TDRSS spacecraft were conceived in the mid-1960s by NASA as a means of using GEO-positioned satellites to eliminate existing ground stations. The main ground terminal becomes Goddard Space Flight Center, through which users other than the Shuttle can also gain access. The TDRSS functions as a relay vehicle, with very little on-board processing except for status reports inserted into the data stream. Use of the TDRSS system by nonNASA agencies currently costs $110/min for forwards, return, and tracking, $24/min for forward service alone, and $8/min for return service only. The spacecraft can store data on board and dump it to the ground station during the limited hours of operation.

Macoughtry, W. O.↗
NASA NTRS1983

Compiling the space shuttle wind tunnel data base: An exercise in technical and managerial innovators

Engineers evaluating Space Shuttle flight data and performance results are using a massive data base of wind tunnel test data. A wind tunnel test data base of the magnitude attained is a major accomplishment. The Apollo program spawned an automated wind tunnel data analysis system called SADSAC developed by the Chrysler Space Division. An improved version of this system renamed DATAMAN was used by Chrysler to document analyzed wind tunnel data and data bank the test data in standardized formats. These analysis documents, associated computer graphics and standard formatted data were disseminated nationwide to the Shuttle technical community. These outputs became the basis for substantiating and certifying the flight worthiness of the Space Shuttle and for improving future designs. As an aid to future programs this paper documents the lessons learned in compiling the massive wind tunnel test data base for developing the Space Shuttle. In particular, innovative managerial and technical concepts evolved in the course of conceiving and developing this successful DATAMAN system and the methods and organization for applying the system are presented.

Kemp, N. D.↗
NASA NTRS1984

Conceptual design and simulator implementation of an automatic terminal approach system

The pilot-machine interface with aircraft automation to increase the safety and utility of single-pilot IFR (instrument flight rules) operations is addressed. An automatic terminal approach system (ATAS), that uses stored instrument approach data to automatically tune aircraft radios and control the aircraft autopilot, was conceived as a means of improving this critical interface. The ATAS automatically flies instrument approach procedures, including the missed approach, and provides for easy pilot interaction to accommodate air traffic control radar vectors and altitude assignments. A research prototype of an ATAS was developed to the extent necessary for a simulation implementation and piloted evaluation. The development of the ATAS concept and the software algorithms is described.

Hinton, D. A.↗
NASA NTRS1983

A novel algorithm for sea surface height estimation using complex SAR data

A method of extracting sea height information from Synthetic Aperture Radar (SAR) complex data was studied. A fundamental SAR ocean imaging model for gravity waves showed that information about the long wave is present in the SAR complex data, especially its phase. Phase demodulation algorithm followed by linear regression and filtering was employed. Only the latter two steps incorporated a priori information that might be available. A relatively simplified simulation indicated that the finite bandwidth of the SAR system imposed the apparently most serious limitation. A preliminary application to SEASAT-SAR complex imagery was encouraging. Information about the long wave, if incorporated into a more sophisticated phase demodulation structure, i.e., at an earlier point in the algorithm, could conceivably mitigate this bandwidth limitation.

Harger, R. O.↗
NASA NTRS1984

Loop Gain and Circuit Parameters for Residual Carrier Tracking in the Advanced DSN Block V Receiver

A circuit level analysis for residual carrier tracking of a deep space network signal by a proposed Block V receiver as conceived by the Receiver Advanced Development Team is presented. The objective is to aid the circuit designer in selection of loop parameters to achieve the required performance objectives. The topics specifically addressed are: (1) loop stability and gain requirements, (2) loop component parametric equations, and (3) phase detector technology.

Young, P. H.↗
NASA NTRS1984

Present capabilities and future requirements for computer-aided geometric modeling in the design and manufacture of gas turbine

Gas turbine engine design requires the ability to rapidly develop complex structures which are subject to severe thermal and mechanical operating loads. As in all facets of the aerospace industry, engine designs are constantly driving towards increased performance, higher temperatures, higher speeds, and lower weight. The ability to address such requirements in a relatively short time frame has resulted in a major thrust towards integrated design/analysis/manufacturing systems. These computer driven graphics systems represent a unique challenge, with major payback opportunities if properly conceived, implemented, and applied.

Caille, E.↗