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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 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
NASA NTRS1979

High Efficiency Cell Development

The specific activity was to improve the tandem junction Cell (TJC) as a high efficiency solar cell. The TJC development was to be consistent with module assembly and should contribute to the overall goals of the Low-Cost Solar Array Project. During 1978, TJC efficiency improved from approximately 11 percent to approximately 16 percent (AMI). Photogenerated current densities in excess of 42 mA/sq cm were observed at AMO. Open circuit voltages as high as 0.615 V were measured at AMO. Fill factor was only 0.68 - 0.75 due to a nonoptimum metal contact design. A device model was conceived in which the solar cell is modelled as a transitor. There are virtually no interconnect or packaging factor systems and the TJC is compatible with all conventional module fabrication systems. A modification of the TJC, the Front Surface Field (FSF) cell, was also explored.

Carbajal, B. G.↗
NASA NTRS1979

Solar heating system final design package

The system is composed of a warm air collector, a logic control unit and a universal switching and transport unit. The collector was originally conceived and designed as an integrated roof/wall system and therefore provides a dual function in the structure. The collector serves both as a solar energy conversion system and as a structural weather resistant skin. The control unit provides totally automatic control over the operation of the system. It receives input data from sensor probes in collectors, storage and living space. The logic was designed so as to make maximum use of solar energy and minimize use of conventional energy. The transport and switching unit is a high-efficiency air-handling system equipped with gear motor valves that respond to outputs from the control system. The fan unit was designed for maximum durability and efficiency in operation, and has permanently lubricated ball bearings and excellent air-handling efficiency.

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NASA NTRS1979

On-board orbit determination for application satellites

A proposal for onboard orbit determination which would rely entirely on reference Doppler beacons located within the Continental United States is presented. Algorithms were conceived which were compatible with small computing machines and sufficiently accurate to maintain an adequate satellite ephemeris. An on board computer equipped with a recursive filter with a fading memory to account for dynamic modeling errors and two reference beacons was found to be necessary for the system to work.

Morduch, G. E.↗
NASA NTRS1979

Recent advances in redox flow cell storage systems

Several features which were conceived and incorporated into complete redox systems that greatly enhanced its ability to be kept in proper charge balance, to be capable of internal voltage regulation, and in general be treated as a true multicell electrochemical system rather than an assembly of single cells that were wired together, were discussed. The technology status as it relates to the two application areas of solar photovoltaic/wind and distributed energy storage for electric utility applications was addressed. The cost and life advantages of redox systems were also covered.

Thaller, L. H.↗
NASA NTRS1977

Power converter design optimization

Utilizing the demonstrated capability of nonlinear programming algorithms, a practical design optimization approach for power converters is established to conceive a design to meet all power-circuit performance requirements and concurrently optimize a defined quantity such as weight or losses. In addition, to facilitate a cost-effective design, the computer-aided approach provides a means to readily assess (1) the weight-efficiency tradeoff, (2) impacts of converter requirements and component characteristics on a given design, and (3) optimum power system configurations.

Yu, Y.↗
NASA NTRS1978

The atmospheres of the Jovian satellites

Observational data on the atmospheres of the Galilean satellites of Jupiter, primarily Io, are reviewed. Io's sodium and hydrogen clouds are discussed along with searches for other species associated with Io. The supply and loss of neutral species to and from Io's clouds are considered, and models for the ionosphere of Io detected by Pioneer 10 are examined. Information and speculation concerning possible atmospheres of Europa, Ganymede, and Callisto are briefly summarized. The suggestion is noted that Ganymede could conceivably maintain a significant (of the order of 1 microbar) atmosphere consisting in large part of oxygen.

Johnson, T. V.↗
NASA NTRS1977

The ESSA solution

ESSA (Electronic Switching Spherical Array) is a fixed truncated spherical antenna with its elements over the complete surface, conceived to satisfy many future antenna system requirements. Constant gain and beam shape throughout large volumetric coverage regions are the principle characteristics. In the present paper, the two existing types of ESSA are discussed. ESSA I is a simple nonphase correcting aperture approach characterized by light weight, low dc power consumption, gain between +7 and +14 dB, and 90% spherical coverage. ESSA II is a phase corrected aperture which would have very low sidelobe levels and improved gain over ESSA I (12 to 22 dB), but would be heavier and require more dc power.

Hockensmith, R. P.↗
NASA NTRS1979

A Mars airplane

An airplane specifically designed for Mars flight is described, emphasizing its conceivable role as an aerial surveyor for visual imaging, gamma-ray and IR reflectance spectroscopy, studies of atmospheric composition and dynamics, and gravity-field, magnetic-field, and electromagnetic sounding. Possible imaging systems and surveying tasks are considered, along with a plausible mission scenario for a fleet of 12 airplanes, which would be taken to Mars in squadrons of four by three Shuttle/IUS Twin Stage/spacecraft carriers. A basic configuration closely resembling that of a competition glider is examined, and four types of airplane are discussed: hydrazine-powered cruisers and landers and electrically powered cruisers and landers. Attention is given to navigation, guidance, and control avionics, vehicle weight, the use of composite materials for the wing, and flight testing on earth.

Clarke, V. C.↗
NASA NTRS1979

Gas drag in primordial circumplanetary envelopes - A mechanism for satellite capture

Known properties of the current solar system and Bodenheimer's (1977) model of early Jovian evolution are employed to develop a mechanism for satellite capture based on gas drag in primordial circumplanetary envelopes. In particular, the deceleration and fragmentation of two parent bodies passing through an extended primordial Jovian nebula may account for the clusters of prograde and retrograde satellites of Jupiter. Subsequently, the fragments probably underwent limited orbital evolution, and were dispersed by collision with a stray body. The heavy element cores of the outer planets may also be due to primordial gas drag capture. Nebular drag capture of the Martian satellites Phobos and Deimos, Neptune's Nereid and Triton, and Saturn's Phoebe and Iapetus is also conceivable.

Pollack, J. B.↗
NASA NTRS1979

Preliminary QCGAT program test results

The paper presents the NASA Lewis program to demonstrate that large engine technology can be applied to general aviation engines to reduce noise, emissions, and fuel consumption. After a Phase I study, two contractors, Garrett AiResearch and AVCO-Lycoming, were selected to design, manufacture, assemble, test, and deliver their Quiet, Clean, General Aviation Turbofan (QCGAT) engines to NASA. Noise, emission, and performance goals and how well they were met are discussed. Noise goals involve take off noise 3.5 n. mi. from runway threshold, sideline noise at .25 n mi. and approach noise 1 n mi. from the runway at an altitude of 370 ft. The AiResearch engines power a stretched Learjet 35 and the Lycoming a specially conceived Beech executive jet, resulting in differing power goals. Thus the thrust goal for the Lycoming was 1622 lb. while the AiResearch goal was 3937 lb. Cruise thrust goals were 485 lb. at Mach 0.6 at 25,000 ft. and 903 lb. at Mach 0.8 at 40,000 ft. respectively. The design of both engines, based on existing cores, is studied, noting such special QCGAT features as new reduction gears, combustor and power turbine. Test results are given, indicating that while the goals for noise and thrust were met those for emissions were only partially met.

Koenig, R. W.↗
NASA NTRS1978

Prebiotic condensation reactions using cyanamide

Condensation reactions in cyanamide, 4-amino-5-imidazole-carboxamide and cyanamide, imidazole systems under dehydrating conditions at moderate temperatures (60 to 100 deg C) were investigated. The cyanamide, imidazole system was used for synthesis of palmitoylglycerols from ammonium palmitate and glycerol. With the addition of deoxythymidine to the former system, P1, P2-dideoxythymidine 5 prime-phosphate was obtained; the same cyanamide, 4-amino-5-imidazole-carboxamide system was used to synthesize deoxythymidine oligonucleotides using deoxythymidine 5 prime-phosphate and deoxythymidine 5 prime-triphosphate, and peptides using glycine, phenylalanine or isoleucine with adenosine 5 prime-triphosphate. The pH requirements for these reactions make their prebiotic significance questionable; however, it is conceivable that they could occur in stable pockets of low interlayer acidity in a clay such as montmorillonite.

Sherwood, E.↗
NASA NTRS1978

The NASA Standard Telemetry and Command Components /STACC/

The Standard Telemetry and Command Components (STACC) were conceived by NASA for use on the Multimission Modular Spacecraft. The components have wider application, however, and already are being considered for many other spacecraft. A programmable Central Unit controls Remote Interface Units via a full duplex data bus, providing data acquisition and command distribution capability throughout the spacecraft. The Central Unit can meet any uplink, time code, and format requirements without hardware changes. Each remote unit can acquire any type of data (serial digital, bi-level, analog, or passive analog) on any channel. A third type of unit is an optional interface providing I/O capability to an on-board computer. The protocols used on the 1Mbps data bus are compatible with MSFC's 'Standard Interfaces for Digital Data, Multiplex Serial Data Acquisition and Distribution Systems (SIDD/MSDADS Standard)'. The bus design saves significant harness weight and simplifies the single point ground and isolation approaches.

Elliott, N. P.↗
NASA NTRS1979

Flight control systems development of highly maneuverable aircraft technology /HiMAT/ vehicle

The highly maneuverable aircraft technology (HiMAT) program was conceived to demonstrate advanced technology concepts through scaled-aircraft flight tests using a remotely piloted technique. Closed-loop primary flight control is performed from a ground-based cockpit, utilizing a digital computer and up/down telemetry links. A backup flight control system for emergency operation resides in an onboard computer. The onboard systems are designed to provide fail-operational capabilities and utilize two microcomputers, dual uplink receiver/decoders, and redundant hydraulic actuation and power systems. This paper discusses the design and validation of the primary and backup digital flight control systems as well as the unique pilot and specialized systems interfaces.

Petersen, K. L.↗
NASA NTRS1979

A new theory of simple classical fluids

The paper presents a unified structural and thermodynamic theory of simple classical fluids in which the interactions between the particles can be represented by spherically symmetric pairwise potentials. Both the excess entropy and the gross features of the radial distribution function are determined mainly by excluded volume effects, which are in turn governed by a hard-core property intrinsic to any pair potential. The potential beyond this effective hard core is considered relatively weak and can be treated as a perturbation. It is also considered essential to sum all subclasses of diagrams to infinite order. The basic form of a diagrammatic scheme which allows both summation and the determination of the structure and excess entropy is presented, and a statement of universality is derived. The statement has been confirmed within the accuracy of present-day computer simulations, and a possible procedure for calculating both the structure and thermodynamics of every physically conceivable pair potential is presented.

Rosenfeld, Y.↗
NASA NTRS1979

Aerocapture - A system design for planetary exploration

The paper presents the results of a study that developed conceptual designs of an atmospheric entry system with moderate to high L/D ratios to establish the concepts of aerocapture into low circular Mars orbits from hyperbolic flyby trajectories. The payloads considered in this study were those currently conceived for the Mars Sample Return (MSR) mission including single mission (SM) and multi-mission (MM) modes. The design concepts developed are also applicable (with small modification) for establishment of closed orbits about Venus and Saturn. The MSR mission payload requires an orbiter, lander, ascent vehicle, and rover, with a total mass of approximately 4000 kg. The emphasis during the study was placed on development of concepts for aerodynamic configuration, the aeroshell design, and a guidance, navigation, and control subsystem.

Cruz, M. I.↗
NASA NTRS1980

Computerized systems analysis and optimization of aircraft engine performance, weight, and life cycle costs

The computational techniques are described which are utilized at Lewis Research Center to determine the optimum propulsion systems for future aircraft applications and to identify system tradeoffs and technology requirements. Cycle performance, and engine weight can be calculated along with costs and installation effects as opposed to fuel consumption alone. Almost any conceivable turbine engine cycle can be studied. These computer codes are: NNEP, WATE, LIFCYC, INSTAL, and POD DRG. Examples are given to illustrate how these computer techniques can be applied to analyze and optimize propulsion system fuel consumption, weight and cost for representative types of aircraft and missions.

Fishbach, L. H.↗
NASA NTRS1980

Recent theoretical work on Cepheids and other types of variables

Some important problems in the theory of Cepheids and of other types of variables are pointed out. Three of these are: (1) large-amplitude mode behavior; (2) convection; and (3) Cepheid masses, which must essentially always be inferred indirectly. Of the several types of indirect mass which can be defined, the inferred masses of the 'beat (or double-mode) Cepheids,' seem to be smaller than one expects for this period range by factors of 2-3. For the nonbeat Cepheids, the indirect masses also appear to be low as compared with conventional stellar evolution theory, but by a smaller amount, say some 20-40 percent. Some conceivable ways of explaining these mass discrepancies are discussed. The question of whether the apparently predominantly radial pulsations of the beat Cepheids could be contaminated with a small admixture of nonradial pulsations, so that the use of purely radial pulsation theory may not be applicable to the beat Cepheids is addressed. Some other conjectures which may bear on ordinary or beat Cepheids are offered.

Cox, J. P.↗
NASA NTRS1978

Report for simultaneous, multiple independently steered beam study for Airborne Electronically Steerable Phased Array (AESPA) program

Design concepts of an array for the formation of multiple, simultaneous, independently pointed beams for satellite communication links were investigated through tradeoffs of various approaches which were conceived as possible solutions to the problem. After the preferred approach was selected, a more detailed design was configured and is presented as a candidate system that should be given further consideration for development leading to a preliminary design. This array uses an attenuator and a phase shifter with every element. The aperture excitation necessary to form the four beams is calculated and then placed across the array using these devices. Pattern analysis was performed for two beam and four beam cases with numerous patterns being presented. Parameter evaluation shown includes pointing accuracy and beam shape, sidelobe characteristics, gain control, and beam normalization. It was demonstrated that a 4 bit phase shifter and a 6 bit, 30 dB attenuator were sufficient to achieve adequate pattern performances. The phase amplitude steered multibeam array offers the flexibility of 1 to 4 beams with an increase in gain of 6 dB if only one beam is selected.

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