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At least 685 records · Page 38

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NASA NTRS1979

Projected techno-economic improvements for advanced solar thermal power plants

The projected characteristics of solar thermal power plants (with outputs up to 10 MWe) employing promising advanced technology subsystems/components are compared to current (or pre-1985) steam-Rankine systems. Improvements accruing to advanced technology development options are delineated. The improvements derived from advanced systems result primarily from achieving high efficiencies via solar collector systems which (1) capture a large portion of the available insolation and (2) concentrate this captured solar flux to attain high temperatures required for high heat engine/energy conversion performance. The most efficient solar collector systems employ two-axis tracking. Attractive systems include the central receiver/heliostat and the parabolic dish.

Fujita, T.↗

NASA NTRS1979

Improvement of selected satellite applications through the use of microwave data

This paper describes an analysis of a data set in which satellite acquired microwave data (Seasat Synthetic Aperture Radar) have been registered with Landsat Multispectral Scanner data and the combined data processed using conventional multichannel spectral pattern recognition programs. Results of this analysis indicate that the combined data set offers improvement in surface classification that is significant to certain applications. A brief description of the registration procedure is given. The improvement in results rendered to selected resource management applications is discussed. The presented results are preliminary due to the short time that the satellite microwave data have been available; however, a more comprehensive analysis is in progress and will be completed during the coming year.

Mooneyhan, D. W.↗

NASA NTRS1980

Improved adherence of T1C coatings to steel

Modified process for RF sputtering of titanium carbide coatings onto 440-C steel has resulted in improved adherence. Small partial pressure of nitrogen, approximately 0.5 percent, during first minutes of deposition markedby improved adherence, friction, and wear properties when compared with coatings applied on sputter-etched surfaces, or oxidized surfaces or in presence of small oxygen partial pressure. X-ray photoelectron spectroscopy and X-ray diffraction were used to characterize resultant coatings.

Brainard, W. A.↗

NASA NTRS1979

An improved Woodward's panel method for calculating leading-edge and side-edge suction forces at subsonic and supersonic speeds

Woodward's panel method for subsonic and supersonic flow was improved by employing control points determined by exactly matching two-dimensional pressure at a finite number of points. The results show great improvement in the predicted pressure distribution of a flapped airfoil. With the paneling scheme of cosine law in both chordwise and spanwise directions, the method is shown to accurately predict leading edge and side edge suction forces of various configurations in subsonic and supersonic flow.

Lan, C. E.↗

NASA NTRS1979

Summary of the Flight Technology Improvement Workshop

Spaceborne instrumentation technology deficiencies are summarized. Recommendations are given for technology development, improvements in existing technology, and policy changes needed to facilitate the use of improved technology. Optical radiometric instruments, attitude control, and electromechanical and power subsystems are considered.

Source record↗

NASA NTRS1980

Improved sample management in the cylindrical-tube microelectrophoresis method

A modification to an analytical microelectrophoresis system is described that improves the manipulation of the sample particles and fluid. The apparatus modification and improved operational procedure should yield more accurate measurements of particle mobilities and permit less skilled operators to use the apparatus.

Smolka, A. J. K.↗

NASA NTRS1980

Conceptual design study of an improved gas turbine powertrain

The conceptual design for an improved gas turbine (IGT) powertrain and vehicle was investigated. Cycle parameters, rotor systems, and component technology were reviewed and a dual rotor gas turbine concept was selected and optimized for best vehicle fuel economy. The engine had a two stage centrifugal compressor with a design pressure ratio of 5.28, two axial turbine stages with advanced high temperature alloy integral wheels, variable power turbine nozzle for turbine temperature and output torque control, catalytic combustor, and annular ceramic recuperator. The engine was rated at 54.81 kW, using water injection on hot days to maintain vehicle acceleration. The estimated vehicle fuel economy was 11.9 km/l in the combined driving cycle, 43 percent over the 1976 compact automobile. The estimated IGT production vehicle selling price was 10 percent over the comparable piston engine vehicle, but the improved fuel economy and reduced maintenance and repair resulted in a 9 percent reduction in life cycle cost.

Chapman, W. I.↗

NASA NTRS1979

Conceptual design study of an improved automotive gas turbine powertrain

Automotive gas turbine concepts with significant technological advantages over the spark ignition (SI) engine were assessed. Possible design concepts were rated with respect to fuel economy and near-term application. A program plan which outlines the development of the improved gas turbine (IGT) concept that best met the goals and objectives of the study identifies the research and development work needed to meet the goal of entering a production engineering phase by 1983. The fuel economy goal is to show at least a 20% improvement over a conventional 1976 SI engine/vehicle system. On the basis of achieving the fuel economy goal, of overall suitability to mechanical design, and of automotive mass production cost, the powertrain selected was a single-shaft engine with a radial turbine and a continuously variable transmission (CVT). Design turbine inlet temperature was 1150 C. Reflecting near-term technology, the turbine rotor would be made of an advanced superalloy, and the transmission would be a hydromechanical CVT. With successful progress in long-lead R&D in ceramic technology and the belt-drive CVT, the turbine inlet temperature would be 1350 C to achieve near-maximum fuel economy.

Wagner, C. E.↗

NASA NTRS1980

Properties of PMR Polyimide composites made with improved high strength graphite fibers

High strength, intermediate modulus graphite fibers were obtained from various commercial suppliers, and were used to fabricate PMR-15 and PMR-2 polyimide composites. The effects of the improved high strength graphite fibers on composite properties after exposure in air at 600 F were investigated. Two of the improved fibers were found to have an adverse effect on the long term performance of PMR composites. The influence of various factors such as fiber physical properties, surface morphology and chemical composition were also examined.

Vannucci, R. D.↗

NASA NTRS1980

Improved components for engine fuel savings

The Engine Component Improvement (ECI) Project formulated to address near term improvements for current engines is described with emphasis on the development of component technologies to reduce the fuel consumption of CF6, JT9D, and JT8D engines. The technical and economical acceptability and the fuel saving potential of nine concepts are demonstrated. Descriptions of these concepts, results of testing, and the status as to entering airline service are presented. Also presented is the status of the remaining concepts still under development.

Antl, R. J.↗

NASA NTRS1979

Experiments for improved positioning by means of integrated Doppler satellite observations and the NNSS broadcast ephemeris

A study to improve position determination using broadcast ephemeris in Doppler data reduction is presented. The uncertainty of the broadcast ephemeris was assessed, and sample autocovariances were computed for acceleration, velocity, and position considering the state disturbance as a signal. An experiment was made in which three stations coobserved 12 passes, and the removal of the radial bias resulted in a chord distance which was in better agreement with the ground survey. In the second experiment, the station positions of the first test simulated the range observations, and the autocovariance function of the acceleration signal in the Cartesian coordinate system was used in an adaptive filtering procedure to improve the state of the satellite in one pass.

Arur, M. G.↗

NASA NTRS1980

Improved position and new optical candidate for A0538-66

An analysis of HEAO 1 modulation collimator data leading to an improved position determination and a new optical counterpart candidate for the transient X-ray source A0538-66 is reported. Data obtained during five outbursts, all of which were separated by 16.7 days or a small multiple thereof, indicates that the outbursts, although of varying duration, intensity, and hardness ratio originated from the same source, at a position of 5 h 35 min 42.7 sec RA and 66 deg 53 arcmin 44 arcsec dec. The improved position determination is found to exclude the previously suggested optical counterpart, and a search of archive plates of the Large Magellanic cloud in the refined error regions has lead to the tentative identification of a B-type star with an observed B variability of 1 mag with the X-ray source.

Johnston, M. D.↗

NASA NTRS1980

Performance improvement of delta wings at subsonic speeds due to vortex flaps

Subsonic wind tunnel tests were conducted to determine performance improvements possible from the use of leading edge vortex flaps (LEVF) on delta wings. Various flap sizes and deflection angles were examined and lift-to-drag ratio improvements of up to 40% were found at moderate angles of attack on 60 deg and 75 deg swept wings. The LEVF is concluded to be effective in moving the wing's leading edge vortex onto the flaps, tilting the vortex-induced force vector forward to produce a thrust or reduce the wing's drag while maintaining attached flow and lift on the wing's upper surface.

Marchman, J. F., III↗

NASA NTRS1980

Development and flight evaluation of automatic flare laws with improved touchdown dispersion

The paper describes the development and flight testing of automatic landing flare laws with improved longitudinal touchdown dispersion. The major sources of touchdown dispersion in current control laws and design objectives of this equipment are discussed. A ground-speed adaptive sink-rate control law and a specified flare trajectory control law were selected for development; the performance of resulting flare laws was evaluated by simulations and flight testing on the NASA TCV B-737 aircraft. These flare laws showed substantial improvement in longitudinal touchdown dispersion, when compared to a more conventional flare law used previously.

Lambregts, A. A.↗

NASA NTRS1982

Improved High-Temperature Seal

High-temperature seals on Space Shuttle Orbiter elevons will be improved by a new flexible seal design that increases the number of leak barriers, allows for thermal expansion and cuts weight by more than two-thirds. Improved seal may be useful in applications where it is necessary to seal gaps between moving surfaces.

Wood, K. E.↗

NASA NTRS1978

An improved viscous characteristics analysis program

An improved two dimensional characteristics analysis program is presented. The program is built upon the foundation of a FORTRAN program entitled Analysis of Supersonic Combustion Flow Fields With Embedded Subsonic Regions. The major improvements are described and a listing of the new program is provided. The subroutines and their functions are given as well as the input required for the program. Several applications of the program to real problems are qualitatively described. Three runs obtained in the investigation of a real problem are presented to provide insight for the input and output of the program.

Jenkins, R. V.↗

NASA NTRS1980

Synthesis of improved phenolic and polyester resins

Thirty-seven cured phenolic resin compositions were prepared and tested for their ability to provide improved char residues and moisture resistance over state of the art epoxy resin composite matrices. Cyanate, epoxy novolac and vinyl ester resins were investigated. Char promoter additives were found to increase the anaerobic char yield at 800 C of epoxy novolacs and vinyl esters. Moisture resistant cyanate and vinyl ester compositions were investigated as composite matrices with Thornel 300 graphite fiber. A cyanate composite matrix provided state of the art composite mechanical properties before and after humidity exposure and an anaerobic char yield of 46 percent at 800 C. The outstanding moisture resistance of the matrix was not completely realized in the composite. Vinyl ester resins showed promise as candidates for improved composite matrix systems.

Delano, C. B.↗

NASA NTRS1981

Guidance and control system research for improved terminal area operations

Several guidance and control system research and development activities aimed at improving the operational capabilities of commercial aircraft in the terminal area are described. The guidance and control systems were designed to improve the capacity and efficiency of terminal area operations, enhance the approach and landing capability of aircraft in adverse weather conditions, and reduce the impact of aircraft noise perceived on the ground. Specific performance features include the ability to capture and track steep glideslopes, use short final approaches, perform flares with reduced longitudinal touchdown dispersion and execute high speed runway rollout and turnoff. Results obtained from simulation studies or flight tests are shown for each of the algorithms.

Hueschen, R. M.↗