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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 1,063 records · Page 59
All sourcesNASA NTRSDOE OSTI
NASA NTRS1995

Wire-Arc-Sprayed Aluminum Protects Steel Against Corrosion

Aluminum coatings wire-arc sprayed onto steel substrates found effective in protecting substrates against corrosion. Coatings also satisfy stringent requirements for adhesion and flexibility, both at room temperature and at temperatures as low as liquid hydrogen. Developed as alternatives to corrosion-inhibiting primers and paints required by law to be phased out because they contain and emit such toxic substances as chromium and volatile organic compounds.

Zimmerman, Frank R.↗
NASA NTRS1995

Mechanical properties of high-temperature superconducting wires

Bending strength, fracture toughness, and elastic modulus data were acquired for YBa2Cu3O(x), Bi2Sr2CaCu2O(x) (Bi,Pb)2Sr2Ca2Cu3O(x), and Tl2Ba2Ca2Cu3O(x) bars. These data and thermal expansion coefficients strongly suggest that the maximum possible tensile strain without fracture of bulk tapes or wires is approximately equals 0.2%. In Ag-clad conductors, residual stresses will be of limited benefit, but fractures produced by larger strains can be accommodated by shunting current through the Ag.

Goretta, K. C.↗
NASA NTRS1995

Wiring test program insulation material related properties

This viewgraph presentation provides an overview of activities at DASA-RI concerning the testing of wires for manned spacecraft, including test facilities, arc-tracking tests, flammability tests, microgravity tests, and standardization, and outlines future activities.

Reher, Heinz-Josef↗
NASA NTRS1995

USAF/WL robust 300 C wire insulation system program status

The objective of this program is to identify, develop, and demonstrate an optimum wire insulation system capable of continuous operation at 300 C which possesses a combination of superior electrical (AC or DC), mechanical, and physical properties over Kapton derived insulations described in MIL-W-81381 and those hybrid materials commonly known as TKT constructions.

Wong, Wing↗
NASA NTRS1995

Metal clad aramid fibers for aerospace wire and cable

High strength light weight metal clad aramid fibers can provide significant weight savings when used to replace conventional metal wire in aerospace cable. An overview of metal clad aramid fiber materials and information on performance and use in braided electrical shielding and signal conductors is provided.

Tokarsky, Edward W.↗
NASA NTRS1996

Proceedings of the F-8 Digital Fly-By-Wire and Supercritical Wing First Flight's 20th Anniversary Celebration

A technical symposium, aircraft display dedication, and pilots' panel discussion were held on May 27, 1992, to commemorate the 20th anniversary of the first flights of the F-8 Digital Fly-By-Wire (DFBW) and Supercrit- ical Wing (SCW) research aircraft. The symposium featured technical presentations by former key government and industry participants in the advocacy, design, aircraft modification, and flight research program activities. The DFBW and SCW technical contributions are cited. A dedication ceremony marked permanent display of both program aircraft. The panel discussion participants included eight of the eighteen research and test pilots who flew these experimental aircraft. Pilots' remarks include descriptions of their most memorable flight experiences The report also includes a survey of the Gulf Air War, and an after-dinner presentation by noted aerospace author and historian Dr. Richard Hallion.

Hodge, Kenneth E.↗
NASA NTRS1996

Proceedings of the F-8 Digital Fly-By-Wire and Supercritical Wing First Flight's 20th Anniversary Celebration: Bibliography Appendices - Volume 2

A technical symposium, aircraft display dedication, and pilots' panel discussion were held on May 27, 1992. to commemorate the 20th anniversary of the first flights of the F-8 Digital Fly-By-Wire (DFBW) and Supercritical Wing (SCW) research aircraft. The symposium featured technical presentations by former key government and industry participants in the advocacy, design, aircraft modification, and flight research program activities. The DFBW and SCW technical contributions are cited. A dedication ceremony marked permanent display of both program aircraft. The panel discussion participants included eight of the eighteen research and test pilots who flew these experimental aircraft. Pilots' remarks include descriptions of their most memorable flight experiences. The report also includes a survey of the Gulf Air War, an after-dinner presentation by noted aerospace author and historian Dr. Richard Hallion.

Hodge, Kenneth E.↗
NASA NTRS1997

Reduction of Calcofluor in Solithane Conformal Coatings of Printed Wiring Boards

An investigation on the outgassing of a pigment employed as a fluorescent medium in conformal coatings has been performed. The conformal coatings in question are used to protect printed wiring boards from environmental hazards such as dust and moisture. The pigment is included in the coating at low concentration to allow visual inspection of the conformal coating for flaw detection. Calcofluor, the fluorescent pigment has been found to be a significant outgasser under vacuum conditions and a potential source of contamination to flight hardware. A minimum acceptable concentration of Calcofluor for flaw detection is desirable. Tests have been carried out using a series of Solithane(TM) conformal coating samples, with progressively lower Calcofluor concentrations, to determine the minimum required concentration of Calcofluor. It was found that the concentration of Calcofluor could be reduced from 0.115% to 0.0135% without significant loss in the ability to detect flaws, while at the same time significant reductions in Calcofluor outgassing and possible contamination of systems could be realized.

Miller, Michael K.↗
NASA NTRS1959

Evaluation of Transpiration-Cooled Turbine Blades with Shells of "Poroloy" Wire Cloth

An experimental investigation was made to evaluate the durability and permeability of a group of transpiration-cooled, strut-supported turbine blades. The porous shells were formed from a woven-wire material. The blades were fabricated by a contractor for the Bureau of Aeronautics. The results of permeability tests indicated that the shell material exhibited large random variations in local permeability, which result in excessive coolant flows and very nonuniform cooling. For this reason no heat-transfer evaluations were made because any results would have been inconclusive. Four blades were investigated for structural soundness in a turbo-jet engine operating at a turbine-inlet temperature of approximately 1670 deg F and a turbine tip speed of approximately 1305 feet per second. The maximum temperature of the porous-shell material was approximately 1050 deg F. Inspection of the first two blades after 10 minutes of engine operation revealed that the tips of both of the blades had failed. For the second pair of blades, an improved tip cap was provided by the use of built-up weld extending from strut tip to shell. One of these blades was then operated for 33 hours without failure, and was found to be in good condition at the end of this time. The second blade of this second pair failed within the first 10 minutes of operation because of a poor bond between shell and strut lands.

Richards, Hadley T.↗
NASA NTRS1997

On Electromagnetic Field-to-Wire Coupling Versus Conducted Injection Techniques

Since the inception of conducted injection techniques to model radiated susceptibility/immunity coupling, considerable debate has ensued regarding its validity. This paper affirms the viewpoint of Szentkuti, (1989) builds upon test results of Adams (1992) and Trout (1996), and discusses Perini's theoretical observations (1993, 1995A, 1995B). Analytical and test results are presented which further demonstrate under what specific conditions conducted and radiated techniques can be correlated, and how the work of Adams, Trout, and Perini fits into the general problem of modeling field-to-wire coupling. At frequencies where transmission line and antenna effects are minimal, conducted immunity techniques provide excellent correlation with analytical and empirical predictions of radiated coupling. From a practical standpoint, conducted injection techniques provide realistic coupling at frequencies and amplitude levels that would be uneconomical to achieve with traditional radiated techniques.

Javor, Ken↗
NASA NTRS1999

Small Explorer WIRE Failure Investigation Report

This paper presents the Small Explorer WIRE Failure Investigation Report in viewgraph form. Some of the diagrams include: 1) Overview of the Pyro Box and key interfaces; 2) Schematic Diagram of the A1020 FPGA (Field Programmable Gate Array) inputs; 3) Three critical FPGA reset signals shown in detail; 4) State machines for firing the cover pyrotechnic devices; 5) Oscillator Overview; and 6) General Crystal Oscillator Startup Characteristics.

Katz, Richard B.↗
NASA NTRS2000

POwer WithOut Wire (POWOW): A SEP Concept for Space Exploration

Electric propulsion has emerged as a cost-effective solution to a wide range of satellite applications. Deep Space 1 demonstrated electric propulsion as a primary propulsion source for a spacecraft. The POwer WithOut Wires (POWOW) concept has been developed as a solar electric propelled spacecraft that would travel to Mars, for example, enter selenosynchronous orbit and then use lasers to beam power to surface installations. This concept has been developed with industrial expertise in high efficiency solar cells, advanced concentrator modules, innovative arrays, and high power electric propulsion systems. The paper will present the latest version of the spacecraft, the technologies involved, possible missions and trip times to Mars and laser beaming options. The POWOW spacecraft is a general purpose solar electric propulsion system that includes technologies that are directly applicable to commercial and government spacecraft with power levels ranging from 4 kW in Low Earth Orbits (LEO) to about 1 MW. The system is modular and expandable. Learning curve costing methodologies are used to demonstrate cost effectiveness of a modular system.

Brandhorst, Henry W., Jr.↗
NASA NTRS2000

Application of Rapid Prototyping and Wire Arc Spray to the Fabrication of Injection Mold Tools (MSFC Center Director's Discretionary Fund)

Rapid prototyping (RP) is a layer-by-layer-based additive manufacturing process for constructing three-dimensional representations of a computer design from a wax, plastic, or similar material. Wire arc spray (WAS) is a metal spray forming technique, which deposits thin layers of metal onto a substrate or pattern. Marshall Space Flight Center currently has both capabilities in-house, and this project proposed merging the two processes into an innovative manufacturing technique, in which intermediate injection molding tool halves were to be fabricated with RP and WAS metal forming.

Cooper, K. G.↗
NASA NTRS2001

Effect of Slow External Flow on Flame Spreading over Solid Material: Opposed Spreading over Polyethylene Wire Insulation

The effect of slow external flow on solid combustion is very important from the view of fire safety in space because the solid material in spacecraft is generally exposed to the low air flow for ventilation. Further, the effect of low external flow on fuel combustion is generally fundamental information for industrial combustion system, such as gas turbine, boiler incinerator and so on. However, it is difficult to study the effect of low external flow on solid combustion in normal gravity, because the buoyancy-induced flow strongly disturbs the flow field, especially for low flow velocity. In this research therefore, the effect of slow external flow on opposed flame spreading over polyethylene (PE) wire insulation have been investigated in microgravity. The microgravity environment was provided by Japan Microgravity Center (JAMIC) in Japan and KC-135 at NASA GRC. The tested flow velocity range is 0-30cm/s with different oxygen concentration and inert gas component.

Fujita, O.↗
NASA NTRS2000

Transport Through Carbon Nanotube Wires

This viewgraph presentation gives an overview of the the current carrying capacity of nanotube wires. Information is given on the motivation for the research, models and assumptions, Bragg reflection and Zener tunneling effects, and the influence of defects. Results show that dI/dv versus V does not increase in a manner commensurate with the increase in the number of subbands; in small diameter nanotubes, Zener tunneling is ineffective; Zener tunneling contributes to current with increase in nanotube diameter; and the increase in dI/dV with bias is much smaller than the increase in the number of subbands.

Anantram, M. P.↗
NASA NTRS2001

Modeling Ballistic Current Flow in Carbon Nanotube Wires

Experiments have shown carbon nanotubes (CNT) to be almost perfect conductors at small applied biases. The features of the CNT band structure, large velocity of the crossing subbands and the small number of modes that an electron close to the band center / Fermi energy can scatter into, are the reasons for the near perfect small bias conductance. We show that the CNT band structure does not help at large applied biases - electrons injected into the non crossing subbands can either be Bragg reflected or undergo Zener-type tunneling. This limits the current carrying capacity of CNT. We point out that the current carrying capacity of semiconductor quantum wires in the ballistic limit is different, owing to its band structure. The second aspect addressed is the relationship of nanotube chirality in determining the physics of metal-nanotube coupling. We show that a metallic-zigzag nanotube couples better than an armchair nanotube to a metal contact. This arises because in the case of armchair nanotubes, while the pi band couples well, the pi* band does not couple well to the metal. In the case of zigzag nanotube both crossing modes couple reasonably well to the metal. Many factors such as the role of curvature, strain and defects will play a role in determining the suitability of nanotubes as nanowires. From the limited view point of metal-nanotube coupling, we feel that metallic-zigzag nanotubes are preferable to armchair nanotubes.

Anantram, M. P.↗
NASA NTRS2001

Transport Through Carbon Nanotube Wires

This viewgraph presentation deals with the use of carbon nanotubes as a transport system. Contact, defects, tubular bend, phonons, and mechanical deformations all contribute to reflection within the nanotube wire. Bragg reflection, however, is native to an ideal energy transport system. Transmission resistance depends primarily on the level of energy present. Finally, the details regarding coupling between carbon nanotubes and simple metals are presented.

Anantram, M. P.↗
NASA NTRS1995

An Advanced Fly-By-Wire Flight Control System for the RASCAL Research Rotorcraft: Concept to Reality

Design features of a new fly-by-wire flight control system for the Rotorcraft-Aircrew Systems Concepts Airborne Laboratory (RASCAL) are described. Using a UH-60A Black Hawk helicopter as a baseline vehicle, the RASCAL will be a flying laboratory capable of supporting the research requirements of major NASA and Army guidance, control, and display research programs. The paper describes the research facility requirements of these pro-rams and the design implementation of the research flight control system (RFCS), with emphasis on safety-of-flight, adaptability to multiple requirements and performance considerations.

Rediess, Nicholas A.↗