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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 1,657 records · Page 92
All sourcesNASA NTRSDOE OSTI
NASA NTRS1974

Monitoring physical and chemical parameters of Delaware Bay waters with an ERTS-1 data collection platform

The author has identified the following significant results. Evaluation of the probe performances during the initial phase indicates that the dissolved oxygen sensor available as part of the package is not sufficiently reliable for long term operation. The turbidity probe requires frequent visits to the site to maintain it in proper operating condition. The cost of these visits would have to be weighed against the information obtained. The conductivity/salinity, temperature, pH, and depth indicators have worked extremely well over the course of the study. Monthly cleanings would maintain all these probes in top operating condition. Currently the accuracy of each measurement returned via satellite is being compared to the accuracy of the probe reading and water samples analyzed in the laboratory.

Klemas, V.↗
NASA NTRS1975

Discussion and theoretical summarization of the experimental data

A summary of research on psychological factors that cause substantial changes in the reliability indicators of an operators work is followed by a conclusion that strong moral-volitional qualities are the basic factors that make the human behavior under conditions of stress effective; emotional subcortical subdominants affect a person's conscious organization and self control in a man machine environment.

Mileryan, Y. A.↗
NASA NTRS1975

Development of beam lead RF integrated circuits

This paper describes the design and development of a set of multifunction VHF/UHF integrated circuits aimed at providing a major improvement in spacecraft radio reliability through low stress operation and the processing of these circuits in beam-lead form. The methods evolved for the high frequency characterization of the devices are discussed together with the design of suitable test fixtures. Typical test results and the distribution of test parameters are presented. A unique carrier for beam-lead devices is described, and the need for such a device is discussed. The application of the carrier to device screening, burn-in and drift measurements is discussed together with the incentives for providing these capabilities. An overview of the integration of the devices into the spacecraft radio is given and candidate assembly processes are discussed. The technology impact of this approach upon future spacecraft radio systems is qualitatively examined.

Kline, A. J.↗
NASA NTRS1979

Design study of a 15 kW free-piston Stirling engine-linear alternator for dispersed solar electric power systems

A conceptual design of a free piston solar Stirling engine-linear alternator which can be designed and developed to meet the requirements of a near-term solar test bed engine with minimum risks was developed. The conceptual design was calculated to have an overall system efficiency of 38% and provide 15kW electric output. The free piston engine design incorporates features such as gas bearings, close clearance seals, and gas springs. This design is hermetically sealed to provide long life, reliability, and maintenance free operation. An implementation assessment study performed indicates that the free piston solar Stirling engine-linear alternator can be manufactured at a reasonable price cost (direct labor plus material) of $2,500 per engine in production quantities of 25,000 units per year. Opportunity for significant reduction of cost was also identified.

Dochat, G. R.↗
NASA NTRS1980

An 8 x 10 to the 5th bit bubble memory cell for spacecraft applications

A multiple chip magnetic bubble memory cell design developed for NASA embodies the low power, low weight, environmental tolerance and reliability necessary for successful operation in spacecraft launch and mission environments. Packaging of multiple chips in a common magnetic bias, drive coil assembly reduces weight and volume overhead per chip and also reduces the number of coil drive components required. This 8 x 10 to the 5th bit cell is conduction cooled and provides a metal and ceramic sealed hermetic chip environment.

Becker, F. J.↗
NASA NTRS1980

Aircraft maintenance. Citations from the International Aerospace Abstracts data base

These citations from the international literature concern various aspects of aircraft maintenance. Both military and civil aviation experience are included. Articles cited concern airline operations, engine and avionics reliability, the use of automatic test equipment, maintenance scheduling, and reliability engineering. This updated bibliography contains 347 citations, 85 of which are new additions to the previous edition.

Zollars, G. F.↗
NASA NTRS1983

Outline of the Mu radar

A middle and upper atmospheric radar system is described. The antenna array consists of 25 groups each of which consists of 19 crossed-Yagis with three elements; each antenna has semiconductor transmitter and receiver, called a module, and each group of 19 antennas works as an independent small radar steering its radar beam under the control of a microcomputer. Thus, the total system consists of 25 small radars of this kind, enabling one to do various sophisticated operations with the system. The system is controlled by two other computers, one for radar controlling (HP9835A) and the other for data taking and on-line analysis (VAX11/750). The computer-controlled system is simple in operation for users and reliable in observation. Very quick beam steering (as quick as in a msec) is also possible because of electronic phase-changing of each module output under control of the microcomputer which is further controlled by the radar controller.

Kato, S.↗
NASA NTRS1983

Positional repeatability measurements of stepper motors at cryogenic temperatures

For cryogenically-cooled infrared instruments and telescopes employed in space, reliable and predictable motor operations at 4 K in vacuum are in most cases necessary. For the Shuttle Infrared Telescope Facility (SIRTF), stepper motors may be employed in a number of applications. A test facility was designed and built for measuring stepper motor positional repeatability, in vacuum, over a temperature range from ambient to liquid helium temperature. Tests regarding positional repeatability were conducted at different motor speeds, directions of motor rotation, step sizes, and power conditions. In addition, tests were performed with respect to the ability of the motor to remain in a position with no power applied to the motor.

Pompea, S. M.↗
NASA NTRS1984

High frequency plasma generator for ion thrusters

The results of a program to experimentally develop two new types of plasma generators for 30 cm electrostatic argon ion thrusters are presented. The two plasma generating methods selected for this study were by radio frequency induction (RFI), operating at an input power frequency of 1 MHz, and by electron cyclotron heating (ECH) at an operating frequency of 5.0 GHz. Both of these generators utilize multiline cusp permanent magnet configurations for plasma confinement and beam profile optimization. The program goals were to develop a plasma generator possessing the characteristics of high electrical efficiency (low eV/ion) and simplicity of operation while maintaining the reliability and durability of the conventional hollow cathode plasma sources. The RFI plasma generator has achieved minimum discharge losses of 120 eV/ion while the ECH generator has obtained 145 eV/ion, assuming a 90% ion optical transparency of the electrostatic acceleration system. Details of experimental tests with a variety of magnet configurations are presented.

Goede, H.↗
NASA NTRS1985

Development of an unsteady aerodynamics model to improve correlation of computed blade stresses with test data

A reliable rotor aeroelastic analysis operational that correctly predicts the vibration levels for a helicopter is utilized to test various unsteady aerodynamics models with the objective of improving the correlation between test and theory. This analysis called Rotor Aeroelastic Vibration (RAVIB) computer program is based on a frequency domain forced response analysis which utilizes the transfer matrix techniques to model helicopter/rotor dynamic systems of varying degrees of complexity. The results for the AH-1G helicopter rotor were compared with the flight test data during high speed operation and they indicated a reasonably good correlation for the beamwise and chordwise blade bending moments, but for torsional moments the correlation was poor. As a result, a new aerodynamics model based on unstalled synthesized data derived from the large amplitude oscillating airfoil experiments was developed and tested.

Gangwani, S. T.↗
NASA NTRS1986

Plasma contactor performance characterization

The plasma contactor performance is outlined. Some performance objectives are given including expellant compatibility, high electron production capability, high ion production capability, high reliability for starting and operation, passive emission control, switchover capability between ion/electron emission, low ion and electron energies, low system mass, and low expellant consumption rate. The basic elements of the hollow cathode are shown along with key features of the plasma source.

Wilbur, P.↗
NASA NTRS1986

Unattended deep space station tracking station development: Monitor and control technology

The major developments leading to successful demonstration of fully unattended operation of a Deep Space Network (DSN) station (DSS 13) are reviewed. Unattended operation was demonstrated by reliably tracking, commanding, and delivering telemetry from the Pioneer 8 spacecraft. Transfer of automated monitor and control technology to DSN implementation is summarized, along with related accomplishments.

Foster, C.↗
NASA NTRS1987

Command and control of the Voyager spacecraft

The Voyager Mission was designed to be conducted using reprogrammable onboard computers. This decision was based on the need for highly reliable semi-autonomous operations of the spacecraft and the lengthy two-way communication times envisioned during the mission. Command and control of the spacecraft is effected by the process through which the programs for these computers are developed. While this results in a relatively passive real-time command and control function, provisions exist for intervention to occur in order to modify or augment the programs or respond to spacecraft anomalies.

Adamski, Terrence P.↗
NASA NTRS1987

Spacecraft on-board SAR image generation for EOS-type missions

Spacecraft on-board synthetic aperture radar (SAR) image generation is an extremely difficult problem because of the requirements for high computational rates (usually on the order of Giga-operations per second), high reliability (some missions last up to 10 years), and low power dissipation and mass (typically less than 500 watts and 100 Kilograms). Recently, a JPL study was performed to assess the feasibility of on-board SAR image generation for EOS-type missions. This paper summarizes the results of that study. Specifically, it proposes a processor architecture using a VLSI time-domain parallel array for azimuth correlation. Using available space qualifiable technology to implement the proposed architecture, an on-board SAR processor having acceptable power and mass characteristics appears feasible for EOS-type applications.

Liu, K. Y.↗
NASA NTRS1987

Noncontacting measurement technologies for space propulsion condition monitoring

This paper describes four noncontacting measurement technologies that can be used in a turbopump condition monitoring system. The isotope wear analyzer, fiberoptic deflectometer, brushless torque-meter, and fiberoptic pyrometer can be used to monitor component wear, bearing degradation, instantaneous shaft torque, and turbine blade cracking, respectively. A complete turbopump condition monitoring system including these four technologies could predict remaining component life, thus reducing engine operating costs and increasing reliability.

Randall, M. R.↗
NASA NTRS1987

0.87-micron CSP diode lasers for spaceborne communications

Index-guided channeled-substrate-planar (CSP) AlGaAs diode lasers are being developed for reliable, high-power operation for use as sources in spaceborne optical communications systems. Although most work on this AlGaAs structure has been aimed at optimizing performance at output wavelengths less than 8400 A, emission in the 8700 A regime is also of interest. In particular, such wavelengths are required for use in the direct detection laser transceiver to be incorporated into NASA's advanced communications technology satellite, in order to avoid absorption of the light by the atmosphere when communicating with ground-based terminals. Lowest order spatial mode and substantially single longitudinal mode output has been observed in 0.87-micron CSP devices in excess of 50 mW cw and 100 mW 50 percent duty-cycle, with rms phase-front aberrations measured to be about lambda/40.

Carlin, D. B.↗
NASA NTRS1988

25-LBF GO2/GH2 space station thruster

Multiple 25-lbf oxygen/gaseous hydrogen thruster assemblies for the Space Station propulsion application were designed and fabricated by Rocketdyne and endurance tested at the NASA/Marshall Space Flight Center. The thrusters incorporate a regeneratively cooled thrust chamber with a nozzle area ratio of 30, a 12-element coaxial injector, an ignition system, and close-coupled propellant valves. The various thruster configurations comprised of mating different injectors and thrust chambers. Over 2 million lbf-sec of impulse was demonstrated at mixture ratios from 3 to 8.4 at vacuum conditions. A thruster was subjected to over 10,000 pulses during which minimum impulse bits of less than 0.5 lb/sec were repeatedly and reliably demonstrated. A total operating time of 25.6 hr was accumulated on the thruster assemblies with one 6.1-hr. continuous firing duration. The thrusters operated between a thrust range of 11.2 and 36.6 lbf. The test results indicate that all major technology issues for long-life gaseous oxygen/gaseous hydrogen thrusters for the Space Station application have been resolved.

Finden, L. E.↗