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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 NTRS1975

Digital control of high-intensity acoustic testing

A high intensity acoustic test system is reported that consists of a reverberation room measuring 18 feet wide by 21 feet long by 26 feet high, with an internal volume of 10,900 cubic feet. The room is rectangular in shape. Acoustic energy is supplied through two 50-Hz cutoff exponential horns about 12 feet long. Each of the two horns has two transducers rated at 4000 acoustic watts each. A gaseous nitrogen supply is used to supply the energy. The equalized electrical signal is corrected by a circuit designed to compensate for the transducer nonlinearity, then fed into one channel of a phase linear power amplifier, then into the transducer. The amplifiers have been modified to increase their reliability. The acoustic energy in the room is monitored by six B and K 1/2-inch condenser microphones. The electrical signal from each microphone is fed into a six channel real time averager to give a spatial average of the signals.

Slusser, R. A.↗
NASA NTRS1976

TPGITF user's manual

The primary purpose of TPG interface (TPGITF) software is to create test patterns, according to a mathematical model, for a real device. In order for the device actually to be tested or to be accurately simulated, a means is required to transform the TPGITF generated test into forms acceptable as input to logic test equipment or to a software logic simulator. The MACRODATA-200 Logic Test System and the LOGSIM logic simulator are the particular systems supported by the TPGITF software. A description is presented of the TPGITF software processor. It is assumed that the reader is familiar with the TPG, LOGSIM, and TOIL systems. Flow charts are given.

Pitts, E. R.↗
NASA NTRS1975

Apollo Soyuz, mission evaluation report

The Apollo Soyuz mission was the first manned space flight to be conducted jointly by two nations - the United States and the Union of Soviet Socialist Republics. The primary purpose of the mission was to test systems for rendezvous and docking of manned spacecraft that would be suitable for use as a standard international system, and to demonstrate crew transfer between spacecraft. The secondary purpose was to conduct a program of scientific and applications experimentation. With minor modifications, the Apollo and Soyuz spacecraft were like those flown on previous missions. However, a new module was built specifically for this mission - the docking module. It served as an airlock for crew transfer and as a structural base for the docking mechanism that interfaced with a similar mechanism on the Soyuz orbital module. The postflight evaluation of the performance of the docking system and docking module, as well as the overall performance of the Apollo spacecraft and experiments is presented. In addition, the mission is evaluated from the viewpoints of the flight crew, ground support operations, and biomedical operations. Descriptions of the docking mechanism, docking module, crew equipment and experiment hardware are given.

Source record↗
NASA NTRS1975

Flight qualification of mortar-actuated parachute deployment systems

A brief discussion outlines background of mortar use in parachute deployment systems. A description of the system operation is presented. Effects of the environment on performance are discussed as well as the instrumentation needed to assess this performance. Power unit qualification and lot qualification for shear pins and cartridges is delineated. Functional mortar system tests are described. Finally, bridle deployment and parachute deployment are discussed.

Pleasants, J. E.↗
NASA NTRS1976

Launch Processing System

This paper presents a functional description of the Launch Processing System, which provides automatic ground checkout and control of the Space Shuttle launch site and airborne systems, with emphasis placed on the Checkout, Control, and Monitor Subsystem. Hardware and software modular design concepts for the distributed computer system are reviewed relative to performing system tests, launch operations control, and status monitoring during ground operations. The communication network design, which uses a Common Data Buffer interface to all computers to allow computer-to-computer communication, is discussed in detail.

Byrne, F.↗
NASA NTRS1976

Effect of adsorbed chlorine and oxygen on the shear strength of iron and copper junctions

Static-friction experiments were performed in ultrahigh vacuum at room temperature on copper, iron, and steel contacts selectively contaminated with oxygen and chlorine in submonolayer amounts. The concentration of the adsorbates was determined with Auger electron spectroscopy and was measured relative to the saturation concentration of oxygen on iron (concentration, 1.0). The coefficient of static friction decreased with increasing adsorbate concentration; however, it was independent of the type of metal and the adsorbate species. The results compared satisfactorily with an extension of the junction growth theory to heterogeneous interfaces. The reduction in interfacial shear strength was measured by the ratio of the shear strength of the interface with an adsorbate concentration of 1.0 and the strength of the clean metal interface. This ratio was about 0.835 for all the systems tested.

Wheeler, D. R.↗
NASA NTRS1976

Digital flight control for the NASA 737 airplane

A brief description of the hardware and software for the digital flight control computers for the NASA 737 airplane is given. Software modules include the basic executive, scheduler, redundancy management, software signal selection, system test, mode logic, pitch axis flight control program and the lateral axis flight control program. A more detailed description of the software development effort is given for the digital flight control software. The software development tasks discussed are: software requirements, development, documentation, control, lab evaluation and formal lab tests. The software development costs are identified and conclusions are drawn concerning the software development effort required to support digital flight control for commercial jet transport applications.

Malcom, L. G.↗
NASA NTRS1976

Flight evaluation of advanced navigation techniques for general aviation using frequency scanning

Experiments on an automatic multisensor navigation concept are being conducted in a Cessna 402B. The test system consists of VOR, DME, and air data sensors controlled by a Hewlett Packard 9820A electronic calculator which processes the data and, by means of a four-state Kalman filter, outputs position and ground and wind velocities to a map display. Novel features which make such a system potentially low-cost include frequency-scanning operation of a single VOR receiver and a single DME transceiver and use of a shed-vortex true airspeed sensor. Results obtained during flight in a local area where six to eight DME NAVAIDS were receivable yielded better than 1/4-mile accuracy.

Jackson, C. T., Jr.↗
NASA NTRS1972

Statistical properties of filtered pseudo-random digital sequences

A tutorial presentation of pseudo-random digital sequences, their generation and properties is given. The results of a study of filtered pseudo-random sequences, and their statistical properties are reported. The generator, to be used in a telemetry communications system test unit, must generate its pseudo-random signals by filtering a long digital sequence. Desired signal properties include: (1) approximately Gaussian amplitude probability density function; and (2) signal spectral envelope approximately that of the filter being used in the generator. Filtered maximum-length sequences have been used for this, and similar applications in the past. The results were good for low-pass filtered sequences when the ratio of digital clock frequency to filter cutoff frequency was between fifteen and twenty. However, for higher values of this ratio, a definite skewing of the amplitude density function was observed.

Weathers, G. D.↗
NASA NTRS1976

Implementation of Large Scale Integrated (LSI) circuit design software

Portions of the Computer Aided Design and Test system, a collection of Large Scale Integrated (LSI) circuit design programs were modified and upgraded. Major modifications were made to the Mask Analysis Program in the form of additional operating commands and file processing options. Modifications were also made to the Artwork Interactive Design System to correct some deficiencies in the original program as well as to add several new command features related to improving the response of AIDS when dealing with large files. The remaining work was concerned with updating various programs within CADAT to incorporate the silicon on sapphire silicon gate technology.

Kuehlthau, R. L.↗
NASA NTRS1977

A review of applications of microwave radiometry to oceanography

The emissivity of sea ice and atmospheric precipitation was investigated. Using the above physics, the data from the Electrically Scanning Microwave Radiometers (ESMR's) on the Nimbus-5 and Nimbus-6 satellites operating at wavelengths of 1.55 cm and 8mm, respectively, can be interpreted in terms of rain rate, ice coverage, and first year versus multi-year ice determination. The rain rate data is being used to establish a climatology of rainfall over the oceans. Both ice and rain data sets have been generated for the Global Atmospheric Research Project Data Systems Test.

Wilheit, T. T., Jr.↗
NASA NTRS1976

Photomultiplier tube development for the 1.06 micrometer wavelength

High speed, electrostatic photomultipliers were developed for use in 400 megabit laser communication systems operating at the 1.06 micron wavelength. A high performance, electrostatic III-V photocathode PMT was shown in communication system tests to perform competitively with solid state and avalanche photodiodes. Signal-induced noise and III-V cathode stability were identified as remaining technical problems while cathode quantum efficiencies of or = 5% at 1.06 micron and 320 picosecond rise and fall time pulse performance were achieved.

Enck, R. S., Jr.↗
NASA NTRS1976

Failure rate analysis of Goddard Space Flight Center spacecraft performance during orbital life

The reported study presents the results of analyses conducted with the aid of both Duane and Weibull growth models. The failure rate values provided may be useful for estimating future space performance, and comparing past, present, and future space performance. Failure rate data from thermal-vacuum system tests are examined and related to the space values. Attention is given to the data base, the time distribution of space malfunctions, limitations on data, and average component reliability for three years in space.

Norris, H. P.↗
NASA NTRS1977

Cell biology experiments conducted in space

A review of cell biology experiments conducted during the first two decades of space flight is provided. References are tabulated for work done with six types of living test system: isolated viruses, bacteriophage-host, bacteria, yeasts and filamentous fungi, protozoans, and small groups of cells (such as hamster cell tissue and fertilized frog eggs). The general results of studies involving the survival of cells in space, the effect of space flight on growing cultures, the biological effects of multicharged high-energy particles, and the effects of space flight on the genetic apparatus of microorganisms are summarized. It is concluded that cell systems remain sufficiently stable during space flight to permit experimentation with models requiring a fixed cell line during the space shuttle era.

Taylor, G. R.↗
NASA NTRS1978

Design of a blood-freezing system for leukemia research

Leukemia research involves the use of cryogenic freezing and storage equipment. In a program being carried out at the National Cancer Institute (NCI), bone marrow (white blood cells) was frozen using a standard cryogenic biological freezer. With this system, it is difficult to maintain the desired rate of freezing and repeatability from sample to sample. A freezing system was developed that satisfies the requirements for a repeatable, constant freezing rate. The system was delivered to NIC and is now operational. This report describes the design of the major subsystems, the analyses, the operating procedure, and final system test results.

Williams, T. E.↗
NASA NTRS1978

A small gas inlet system for orbital mass-spectrometer calibrations

A gas inlet system is described for generating precise gas pressures that are to be used as calibration references for the mass spectrometers aboard the dual air density Explorer satellites. This gas inlet system was developed as an inflight calibration technique in which a known amount of onboard gas is released in the satellite cavity and is detected by the mass spectrometer. Although several flight mass spectrometer experiments have been proposed, none make use of the inflight calibration technique described in this report. Laboratory measurements and calibration of the metering leak technique for the gas inlet systems are discussed. The systems tested have metering leak rates between 2 and 4 microliters/sec at 298 K for argon-40, and they produce molecular flow up to 100 torr, which is the highest test pressure in this experiment. Test data show that metering leak rates are reproducible within 1 percent of established means for helium-3, helium-4, and argon-40.

Smith, A.↗
NASA NTRS1978

Advanced space engine powerhead breadboard assembly system study

The objective of this study was to establish a preliminary design of a Powerhead Breadboard Assembly (PBA) for an 88 964-Newton (20,000-pound) thrust oxygen/hydrogen staged combustion cycle engine for use in orbital transfer vehicle propulsion. Existing turbopump, preburner, and thrust chamber components were integrated with interconnecting ducting, a heat exchanger, and a control system to complete the PBA design. Cycle studies were conducted to define starting transients and steady-state balances for the completed design. Specifications were developed for all valve applications and the conditions required for the control system integration with the facility for system test were defined.

Campbell, R. G.↗