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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 181 records · Page 10

Large silver-cadmium technology program

The effects of varying cell design on operation factors on the electrochemical performance of sealed, silver-cadmium cells were determined. A factorial experiment was conducted for all test cells constructed with organic separators. Three operating factors were evaluated: temperature, depth of discharge, and charge rate. The six construction factors considered were separator, absorber, electrolyte quantity, cadmium electrode type, cadmium-to-silver ratio, and auxiliary electrode. Test cells of 4 ampere-hour capacity were fabricated and cycled. The best performing cells, on a 94 minute orbit, at 40% depth of discharge, were those containing silver-treated fibrous sausage casings as the separator, and Teflon-ated, pressed cadmium electrodes. Cycling data of cells with inorganic separators (Astroset) are given. Best performance was shown by cells with nonwoven nylon absorbers. Rigid inorganic separators provided the best barrier to silver migration.

Charlip, S.↗

A preliminary study of containment concepts for aircraft landing on elevated STOL-ports

A preliminary study of containment systems for aircraft landing on elevated STOL-ports was conducted as part of an overall study of human acceptance problems associated with STOL operations. The study included a survey and feasibility study of different concepts and a computer analysis of four arrestment systems. The principal conclusion was that a system referred to as the FAA system appears to offer the greatest promise. In this system, standard arresting gear cables are stretched across the roof-top, at roughly 100-foot intervals, but are shielded over the 100-foot-wide primary landing strip. Thus a pilot can land with an arresting hook down, but will not contact the cable unless he swerves off the landing strip, either because he has made a bad landing, or because his landing gear has failed. It was also noted that a suitable curb or guard rail should be developed. Presently available arresting gears and nylon net barriers were considered satisfactory for the overshoot problem.

Haviland, J. K.↗

Flight-and ground-test evaluation of pyrrone foams

Two Pyrrone materials, pure Pyrrone foam with a density of 481 kg/cu m and hollow glass microsphere-Pyrrone composite with a density of 962 kg/cu m, were tested in the Langley 20-inch hypersonic arc heated tunnel at pressure levels from 0.06 to 0.27 atm and heating rates from 1.14 to 11.4 MW/sq m. The 481-kg/cu m Pyrrone foam was also flight tested as an experiment aboard a Pacemaker test vehicle. The results of the ground tests indicated that the thermal effectiveness of the 481-kg/cu m Pyrrone foam was superior to the 962-kg/cu m glass sphere-Pyrrone composite. The 481-kg/cu m Pyrrone foam had approximately one-half the thermal effectiveness of low density phenolic nylon. The 481-kg/cu m Pyrrone foam experienced random mechanical char removal over the entire range of test conditions. Char thermal property inputs for an ablation computer program were developed from the ground test data of the 481-kg/cu m Pyrrone foam. The computer program using these developed char thermal properties, as well as the measured uncharred material properties, adequately predicted the in-depth temperature histories measured during the Pacemaker flight.

Mclain, A. G.↗

Development of flame resistant metal and metal-glass blended structures

A description is given of the design and fabrication of candidate flame-resistant woven and knitted fabrics, tapes, webbings, and cords as replacements for those items used in the Apollo spacecraft which were previously made of nylon and polyester. Structures made from Chromel R metal fibers (74% Ni, 20% Cr, 2-1/2% Fe, 2-1/2% Al, 1/2% Si, 1/2% Mo), Beta glass fibers and high-temperature organic fibers such as PBI (polybenzimidazole) were developed and evaluated. The feasibility of improving the performance of selected fabrics by using CNR (carboxy nitroso rubber) or other nonflammable coatings were also investigated.

Coskren, R. J.↗

Portable life support for instrumentation of an offshore platform

A compressor was used to supply air through a nylon hose to the offshore platform field engineer working at the bottom of the piling. Air quality in the pile was sampled periodically for carbon dioxide, carbon monoxide, hydrogen sulfide, and combustible gases by an universal tester and an explosion meter.

Mull, M. M.↗

Dielectric siphons.

The normally weak polarization force density, exerted on insulating dielectric liquids by a nonuniform electric field, is enhanced if high pressures are used. The nonuniform electric field acts as an elastic ?wall' to contain and guide the dielectric fluid. A general theory for these electrohydrodynamic (EHD) conduits has been developed. An illustrative example of the EHD conduits is the dielectric siphon consisting of two U-shaped electrodes held adjacent to each other by insulating nylon screws.

Jones, T. B.↗

Experimental investigation of strains in fabric under biaxial and shear forces.

The paper defines the experimental phase of an objective to obtain the mechanical characteristics and coefficients required by the generalized form of Hooke's law for nylon-polyurethane-coated fabric. Test specimens were cylindrical fabric sleeves and were loaded in axial tension by an Instron, in hoop tension by pressurizing, and in shear by a torquing fixture. An extensive amount of strain data is included for a wide combination of the three membrane loads. The tests indicate highly nonlinear stress-strain characteristics of the fabric and a strong dependency on all three membrane loads.

Alley, V. L., Jr.↗

Polymer-gas reactions (air pollutants: NO2 and SO2) as function of pressure, UV light, temperature, and morphology: A survey

Reactions of various polymers, such as polystyrene and its stereo-specific isomers, butylrubber, nylon, etc., with nitrogen dioxide and sulfur-dioxide were studied over the past few years. More recently, work has been initiated on the influence of polymer morphology on degradation of polymers in presence of these gases, near UV radiation and oxygen. Unexpected effects have been observed during chain scission near room temperature. Thus, for instance, isotactic polystyrene of various crystallinities, as far as extent and type are concerned, show marked differences in their degradation characteristics. Thus, for instance, crystalline polymers show faster degradation than amorphous ones, which seems to be contrary to expectations. However, this phenomenon can be explained in quite a consistent manner. The importance of all these reactions in connection with air pollution is briefly discussed.

Jellinek, H. H. G.↗

Mechanical component screening for scanner

The critical mechanical components of the scan mirror mechanism are described and their evaluation and screening procedures are discussed. A bumper/damper unit is used in the design to reverse motion of the mirror and effect scan and retrace cycles. A wear evaluation was conducted on the bumper impact surfaces that established nylon 6-10 as an acceptable material. The elastomeric dampers were subjected to thermal vacuum tests for condensables and outgassing as well as parametric life tests. The flexure pivots that support the mirror were tested to establish a curve of stress plotted as a function of cycles to failure for rotational operation. The pivots met the life requirement of 150,000,000 cycles at a + or - 2.9 deg amplitude during fatigue testing. Screening procedures were established for dampers and flexure pivots to obtain flight quality components.

Olson, J. L.↗

Ply-tear webbing energy absorber

Ply-tear webbing is essentially two plain webbings that are bound together by a portion of the warps and that can be torn apart and do work by breaking the binders. Nylon webbing were woven to range in tear force from 1 to 10 kilonewtons. This force is substantially independent of speed, which was as high as 100 m/sec in some cases. A specific energy absorption of 90 J/g was achieved in the dry state. However, lower rated webbings that absorb approximately 40 J/g are recommended for use in practice where it is acceptable.

Stevens, G. W. H.↗

Ablation and radiation coupled viscous hypersonic shock layers, volume 1

The results for a stagnation-line analysis of the radiative heating of a phenolic-nylon ablator are presented. The analysis includes flow field coupling with the ablator surface, equilibrium chemistry, a step-function diffusion model and a coupled line and continuum radiation calculation. This report serves as the documentation, i e. users manual and operating instructions for the computer programs listed in the report.

Engel, C. D.↗

Ablation and radiation coupled viscous hypersonic shock layers, volume 2

A computer program can be used to determine the radiative flux and flux divergence through a nonisothermal planar slab of gas is described. The program considers species typical of air at high temperatures and nylon or carbon phenolic ablation products. The equations solved are for a variable optical depth line and continuum gas model using species cross sections and line widths as the basic data.

Engel, C. D.↗

Correlation of new hypervelocity impact data by threshold penetration relations

Threshold penetration data are established by impacting spherical projectiles onto 2024 aluminum single-wall targets. Nylon and cadmium projectiles were used at impacting velocities from 3.0 to 6.8 km/s and 7.9 to 8.5 km/s respectively. These data are combined with existing data and compared with three threshold relations to assess their respective validities over a wide range of projectile densities. Two of these relations were validated over the extended range of projectile densities.

Hayduk, R. J.↗

Ablation and radiation coupled viscous hypersonic shock layers.

Coupled ablator shock layer solutions for the stagnation point are presented for typical hyperbolic entry atmospheric flight conditions. These solutions were obtained by numerically solving the stagnation line shock layer equations and quasi-steady ablator equations. These equations included ablation and radiation coupling within the viscous shock layer, line and continuum radiation for both air and phenolic-nylon ablation species and local thermodynamic equilibrium throughout. The results presented provide a sound basis for understanding many of the processes characteristic of hypersonic shock layer heating.-

Engel, C. D.↗

Effects of simulated space environment on Skylab parasol material

A material consisting of ripstop nylon bonded to the Mylar side of aluminized Mylar film was used to construct the first Skylab parasol. The mechanical properties of elongation and tensile strength and the radiative properties of solar absorptance and thermal emittance were measured before and after exposure to simulated solar radiation at intensities of 1.0 and 3.5 solar constants for exposure times as long as 947 hours or 3316 equivalent solar hours. The accelerated testing indicated more severe degradation than was experienced in the real-time test (1 solar constant). The results predicted that this material could have given satisfactory performance throughout the planned lifetime of the Skylab workshop.

Slemp, W. S.↗

Steady state thermal radiometers

A radiometer is described operating in a vacuum under steady state conditions. The front element is an aluminum sheet painted on the outer side with black or other absorptive material of selected characteristics. A thermocouple is bonded to the inner side of the aluminum sheet. That is backed by highly insulative layers of glass fiber and crinkled, aluminized Mylar polyester. Those layers are backed with a sturdy, polyester sheet, and the entire lamination is laced together by nylon cords. The device is highly reliable in that it does not drift out of calibration, and is significantly inexpensive.

Loose, J. D.↗

Interaction of graphite and ablative materials with CO2-laser, carbon-arc, and xenon-arc radiation

The behavior of graphite and several charring ablators in a variety of high radiative heat flux environments was studied in various radiative environments produced by a CO2 laser and a carbon arc facility. Graphite was also tested in xenon arc radiation. Tests were conducted in air nitrogen, helium, and a mixture of CO2 and nitrogen, simulating the Venus atmosphere. The experimental results are compared with theoretical results obtained with a one dimensional charring ablator analysis and a two dimensional subliming ablator analysis. Photomicroscopy showed no significant differences in appearance or microstructure of the charring ablators or graphite after testing in the three different facilities, indicating that the materials respond fundamentally the same to the radiation of different frequencies. The performance of phenolic nylon and graphite was satisfactorily predicted with existing analyses and published material property data.

Brewer, W. D.↗

Evaluation of the energy transfer in the char zone during ablation. Part 2: In-depth response of ablative composites, volume 1

The decomposition of ablative composites is described along with the transport phenomena of pyrolysis gases which result from the decomposition of these plastics as they flow through the porous char of char-forming ablators. The pyrolysis products are those formed by the thermal degradation of nylon-phenolic resin and silicone elastomer composites. Emphasis is placed on the nature and extent of chemical reactions of the pyrolysis products and the char, along with the energy absorbed by the combined pyrolysis and char zone. Chemical reactions with thermodynamically consistent kinetic data are determined in order to develop a realistic analysis for predicting the thermal performance of ablative heat shields.

Pike, R. W.↗