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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 1,675 records · Page 93
All sourcesNASA NTRSDOE OSTI
NASA NTRS1977

Proximity sensor technology for manipulator end effectors

Optical proximity sensing devices suitable for hand mounting on a manipulator are described, which use near IR LED light sources operating at 0.94 micron and silicon detectors, with appropriate signal processing so that the data are unaffected by ambient light. Laboratory tests with simple proximity sensors are described. Extension of the same techniques to yield multipoint or digital sensors is also discussed. A cooperative proximity sensor concept is described, which employs a composite mirror attached to the work piece to generate an unambiguous set of position and orientation signals. A very rudimentary experiment in local control of a manipulator with a pair of hand mounted proximity sensors is also described.

Johnston, A. R.↗
NASA NTRS1976

Automatic vehicle monitoring

Automatic vehicle monitoring systems are discussed. In a baseline system for highway applications, each vehicle obtains position information through a Loran-C receiver in rural areas and through a 'signpost' or 'proximity' type sensor in urban areas; the vehicle transmits this information to a central station via a communication link. In an advance system, the vehicle carries a receiver for signals emitted by satellites in the Global Positioning System and uses a satellite-aided communication link to the central station. An advanced railroad car monitoring system uses car-mounted labels and sensors for car identification and cargo status; the information is collected by electronic interrogators mounted along the track and transmitted to a central station. It is concluded that automatic vehicle monitoring systems are technically feasible but not economically feasible unless a large market develops.

Bravman, J. S.↗
NASA NTRS1977

Shuttle Experimental Radar for Geological Exploration (SERGE); antenna and integration concept definition study

The baseline configuration defined has the SERGE antenna panel array mounted on the OFT-2 pallet sufficiently high in the bay that negligible amounts of radiation from the beam are reflected from orbiter surfaces into the shuttle payload bay. The array is symmetrically mounted to the pallet along the array long dimension with the pallet at the center. It utilizes a graphite epoxy trusswork support structure. The antenna panels are of SEASAT engineering model design and construction. The antenna array has 7 panels and a 7-way naturally tapered coax corporate feed system. The performance of the system is predicted to exceed 33 db gain, have -15 db sidelobes in the E-plane and even lower in the H-plane, and have and E-plane beamwidth less than 2.2 deg, all within performance specification. The primary support structure is predicted to exceed the specified greater than 25 hertz fundamental frequency, although individual panels will have hertz fundamental frequency.

Kierein, J. W.↗
NASA NTRS1978

Gas turbine engine with convertible accessories

Drive means for connecting a gas turbine engine to its accessories are so constructed as to allow the accessories to be selectively positioned to any one of several predetermined circumferential positions about the perimeter of the engine. This feature permits convenient mounting of the same engine upon vehicles demanding radically different engine mounting arrangements.

Sargisson, D. F.↗
NASA NTRS1976

Development of birefringent filters for spaceflight

The critical problem for flight of a birefringent filter is the shock mounting of the calcite. The design presented here bonds the calcite block with silicon rubbers to the calcite holder. The calcite together with its all necessary polarizers and rotating achromatic plates are mounted together in units called a filter module. By using a set of modules containing calcite crystals of differing lengths, a filter can be produced. A description of the modules is given. Also described is a container for the filter modules, which can be used both to hermetically seal the system or contain an index matching oil. The response of a filter element while being controlled by the Lockheed Temperature Control is described and the determination of the wavelength sensitivity to temperature of calcite is explained. Operation of the filter using a software control algorithm instead of a hardware temperature controller is shown. Some radiation considerations of filter systems are given.

Title, A. M.↗
NASA NTRS1978

Space shuttle orbiter reaction control system interactions with the vehicle flow field

Test data on the effect of the interaction between the space shuttle orbiter rear-mounted reaction control system jets and the flow over the vehicle in the atmosphere are analyzed with particular attention to yaw angle effects. Masted tank-plus-orbiter jet interactions resulting from combinations of forward and rear-mounted reaction control jets being fired prior to external tank staging are also documented. The primary correlating parameter used for the mated data is a single-jet momentum ratioed to free-stream momentum. An analytic model for computing reaction control system interactions for all control combinations used for mated vehicle coast is included.

Rausch, J. R.↗
NASA NTRS1978

Study of fuel systems for LH2-fueled subsonic transport aircraft, volume 1

Several engine concepts examined to determine a preferred design which most effectively exploits the characteristics of hydrogen fuel in aircraft tanks received major emphasis. Many candidate designs of tank structure and cryogenic insulation systems were evaluated. Designs of all major elements of the aircraft fuel system including pumps, lines, valves, regulators, and heat exchangers received attention. Selected designs of boost pumps to be mounted in the LH2 tanks, and of a high pressure pump to be mounted on the engine were defined. A final design of LH2-fueled transport aircraft was established which incorporates a preferred design of fuel system. That aircraft was then compared with a conventionally fueled counterpart designed to equivalent technology standards.

Brewer, G. D.↗
NASA NTRS1978

ATS-6 flight accelerometers

Five accelerometers mounted near the adapter base of the Titan 3-C launch vehicle and three on the hub of the ATS-F spacecraft provided (1) data for verifying basic spacecraft mode shapes and frequencies during powered flight while attached to the launch vehicle; (2) failure mode detection and diagnostic information on in-flight anomalies; and (3) data to be used in the design of future spacecraft to be flown on the Titan 3-C. Because data from the instruments mounted on the spacecraft hub passed through an in-flight disconnect at the separation plane between the transtage and ATS-F, the moment this connector was broken, the signal to the telemetry system showed a step function change. By monitoring these telemetry traces on the ground at appropriate times during flight sequences, a positive indication of spacecraft separation was obtained. Flight data showing dynamic response at spacecraft launch vehicle interface and at the top of ATS spacecraft during significant launch events are presented in tables.

Mattson, R.↗
NASA NTRS1977

A miniature 48-channel pressure sensor module capable of in situ calibration

A new high data rate pressure sensor module with in situ calibration capability has been developed by the Langley Research Center to help reduce energy consumption in wind-tunnel facilities without loss of measurement accuracy. The sensor module allows for nearly a two order of magnitude increase in data rates over conventional electromechanically scanned pressure sampling techniques. This module consists of 16 solid state pressure sensor chips and signal multiplexing electronics integrally mounted to a four position pressure selector switch. One of the four positions of the pressure selector switch allows the in situ calibration of the 16 pressure sensors; the three other positions allow 48 channels (three sets of 16) pressure inputs to be measured by sensors. The small size of the sensor module will allow mounting within many wind-tunnel models, thus eliminating long tube lengths and their corresponding slow pressure response.

Gross, C.↗
NASA NTRS1977

Dynamic model for an instrument pointing system

The instrument pointing system concept discussed in the present paper was developed for Spacelab missions. The system is mounted on soft shockmounts to minimize Shuttle disturbances (such as man motion, thruster firings, etc.) and to reduce the effect of large center of mass offsets between the instrument and the pointing system gimbal axes. The instrument pointing system is soft mounted to the Spacelab pallet located in the Orbiter payload bay. The nonlinear model, incorporating the dynamic equations of motion, the controller equations and the definition of sensor dynamics and gimbal bearing friction, is given, along with a system of linearized equations of motion of the Space Shuttle Orbiter and instrument pointing system (linearized model).

Howell, J. T.↗
NASA NTRS1978

Plasma disturbances created by probes in the ionosphere and their potential impact on low-energy measurements considered for Spacelab

An experimental investigation of the perturbations created by small conducting bodies immersed in highly rarefied plasma streams was carried out for spherical and cylindrical geometries in the plasma wind tunnel facility at Marshall Space Flight Center. These measurements, as well as the results of previous studies conducted in that facility, were evaluated for the purpose of demonstrating the potential hazards of interference between instruments mounted on diagnostic packages. The scaling in the laboratory work is sufficiently accurate to provide a rough indication of the spatial extent and magnitude of the disturbances created by small probes of 3-6 cm in diameter mounted on board spacecraft moving at altitudes of 150-200 km. The results of such studies have direct application to the location of probes on instrument packages and design of experiments in future space shuttle/Spacelab missions.

Stone, N. H.↗
NASA NTRS1977

Optical design of a stigmatic spectroheliometer for photometric studies of dynamic phenomena at extreme-ultraviolet wavelengths

The design of a stigmatic spectroheliometer for photometric studies of dynamic phenomena in the solar atmosphere at extreme ultraviolet (EUV) wavelengths is described. The normal-incidence spectrometer requires only one reflective surface, and is equipped with a series of exit slits and associated one-dimensional detector arrays that are mounted at the secondary (vertical) foci of the concave diffraction grating. It is shown that such a spectrometer mounted at the focus of an off-axis paraboloid telescope mirror of the size employed in the EUV spectroheliometer flown on Skylab could record monochromatic images of a 2 x 2 (arcmin) sq field-of-view with a spatial resolution element of 1 x 1 (arcsec) sq in a time of 4 s, 24 s, or 4 min, depending on whether the region studied is flaring, active, or quiet. The resulting spectroheliograms would have an average photometric precision of 10% and a spectral purity of 0.1 A.

Huber, M. C. E.↗
NASA NTRS1978

Cam-Operated Pitch-Change Apparatus

A pitch-change apparatus for a ducted thrust fan having a plurality of variable pitch blades employs a camming ring mounted coaxially at the hub at an axially fixed station along the hub axis for rotation about the hub axis both with the blades and relative to the blades. The ring has a generally spherical outer periphery and a plurality of helical camming grooves extending in a generally spherical plane on the periphery. Each of the variable pitch blades is connected to a pitch-change horn having a cam follower mounted on its outer end, and the camming ring and the horns are so arranged about the hub axis that the plurality of followers on the horns engage respectively the plurality of helical camming grooves. Rotary drive means rotates the camming ring relative to the blades to cause blade pitch to be changed through the cooperative operation of the camming grooves on the ring and the cam followers on the pitch-change horns.

Barnes, P. E.↗
NASA NTRS1978

Electronically scanned pressure sensor module with in SITU calibration capability

This high data rate pressure sensor module helps reduce energy consumption in wind tunnel facilities without loss of measurement accuracy. The sensor module allows for nearly a two order of magnitude increase in data rates over conventional electromechanically scanned pressure sampling techniques. The module consists of 16 solid state pressure sensor chips and signal multiplexing electronics integrally mounted to a four position pressure selector switch. One of the four positions of the pressure selector switch allows the in situ calibration of the 16 pressure sensors; the three other positions allow 48 channels (three sets of 16) pressure inputs to be measured by the sensors. The small size of the sensor module will allow mounting within many wind tunnel models, thus eliminating long tube lengths and their corresponding slow pressure response.

Gross, C.↗
NASA NTRS1978

Assessment of the potential of solar thermal small power systems in small utilities

The potential economic benefit of small solar thermal electric power systems to small municipal and rural electric utilities is assessed. Five different solar thermal small power system configurations were considered in three different solar thermal technologies. The configurations included: (1) 1 MW, 2 MW, and 10 MW parabolic dish concentrators with a 15 kW heat engine mounted at the focal point of each dish, these systems utilized advanced battery energy storage; (2) a 10 MW system with variable slat concentrators and central steam Rankine energy conversion, this system utilized sensible thermal energy storage; and (3) a 50 MW central receiver system consisting of a field of heliostats concentrating energy on a tower-mounted receiver and a central steam Rankine conversion system, this system also utilized sensible thermal storage. The results are summarized in terms of break-even capital costs. The break-even capital cost was defined as the solar thermal plant capital cost which would have to be achieved in order for the solar thermal plants to penetrate 10 percent of the reference small utility generation mix by the year 2000. The calculated break-even capital costs are presented.

Steitz, P.↗
NASA NTRS1969

Wind tunnel

A supersonic wind wind tunnel is described for testing several air foils mounted in a row. A test section of a wind tunnel contains means for mounting air foil sections in a row, means for rotating each section about an axis so that the angle of attack of each section changes with the other sections, and means for rotating the row with respect to the air stream so that the row forms an oblique angle with the air stream.

Wilson, E. M.↗
NASA NTRS1978

Implications of cavity, topographic and geologic influences on tilt and strain observations

Tilt and strain observations are importantly (pathologically at the 100%, typically at the few 10s% level) affected by cavities, topography, and geological inhomogenities; gravity observation are practically unaffected. The traditional earth tide observatory and abandoned mine or tunnel is a very poor place to measure body tides because of the complicated cavities, topography and geology. Instead, the ideal site for observing the body tide is in flat terrain with horizontally layered, mechanically homogeneous geology. Strain will be measured with long surface- or trench-mounted laser strain meters and tilt with long, surface- or trench mounted liquid levels, or with borehole tiltmeters. Horizontal geological discontinuities can produce large perturbations of the tilt and strain tides, and these perturbations, using the known homogeneous tidal strains and tilts, can be used in exploring local structure in favorable cases and, through possible time variations of tidal admittances, in predicting earthquakes.

Harrison, J. C.↗
NASA NTRS1979

Field Measurements of Penetrator Seismic Coupling in Sediments and Volcanic Rocks

Field experiments were conducted to determine how well a seismometer installed using a penetrator would be coupled to the ground. A dry-lake bed and a lava bed were chosen as test sites to represent geological environments of two widely different material properties. At each site, two half-scale penetrators were fired into the ground, a three-component geophone assembly was mounted to the aft end of each penetrator, and dummy penetrators were at various distances to generate seismic signals. These signals were detected by the penetrator-mounted geophone assembly and by a reference geophone assembly buried or anchored to surface rock and 1-m from the penetrator. The recorded signals were digitized, and cross-spectral analyses were performed to compare the observed signals in terms of power spectral density ratio, coherence, and phase difference. The analyses indicate that seismometers deployed by penetrators will be as well coupled to the ground as are seismometers installed by conventional methods for the frequency range of interest in earthquake seismology.

Nakamura, Y.↗