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  • 1
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    Curved-flow, rolling-flow, and oscillatory pure-yawing wind-tunnel test methods for determination of dynamic stability derivatives (1981)
    In:  CASI
    Details
    Publikationsdatum: 2011-10-14
    Beschreibung: The test capabilities of the Stability Wind Tunnel of the Virginia Polytechnic Institute and State University are described, and calibrations for curved and rolling flow techniques are given. Oscillatory snaking tests to determine pure yawing derivatives are considered. Representative aerodynamic data obtained for a current fighter configuration using the curved and rolling flow techniques are presented. The application of dynamic derivatives obtained in such tests to the analysis of airplane motions in general, and to high angle of attack flight conditions in particular, is discussed.
    Schlagwort(e): AERODYNAMICS
    Materialart: AGARD Dyn. Stability Parameters; 13 p
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  • 2
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    An atomic oxygen facility for studying polymer materials for spacecraft applications (1984)
    In:  CASI
    Details
    Publikationsdatum: 2006-02-14
    Beschreibung: A nozzle beam facility utilizing microwave discharge on a helium carrier gas seeded with oxygen to produce atomic oxygen fluxes of the order of 10 to the 15th power atoms/cu cm/sec is described. In addition, limited test results obtained from exposing a graphite/epoxy composite and Kapton (H) film are presented in terms of mass loss measurements and changes in surface morphology.
    Schlagwort(e): NONMETALLIC MATERIALS
    Materialart: NASA. Goddard Space Flight Center 13th Space Simulation Conf.; p 169-192
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  • 3
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    In-flight lift and drag measurements on a first generation jet transport equipped with winglets (1982)
    In:  CASI
    Details
    Publikationsdatum: 2006-02-14
    Beschreibung: A KC-135A aircraft equipped with wing tip winglets was flight tested to demonstrate and validate the potential performance gain of the winglet concept as predicted from analytical and wind tunnel data. Flight data were obtained at cruise conditions for Mach numbers of 0.70, 0.75, and 0.80 at a nominal altitude of 36,000 ft. and winglet configurations of 15 deg cant/-4 deg incidence, 0 deg cant/-4 deg incidence, and baseline. For the Mach numbers tested the data show that the addition of winglets did not affect the lifting characteristics of the wing. However, both winglet configurations showed a drag reduction over the baseline configuration, with the best winglet configuration being the 15 deg cant/-4 deg incidence configuration. This drag reduction due to winglets also increased with increasing lift coefficient. It was also shown that a small difference exists between the 15 deg cant/-4 deg incidence flight and wind tunnel predicted data. This difference was attributed to the pillowing of the winglet skins in flight which would decrease the winglet performance.
    Schlagwort(e): AERODYNAMICS
    Materialart: KC-135 Winglet Program Rev.; p 103-116
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  • 4
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    KC-135 winglet program overview (1982)
    In:  CASI
    Details
    Publikationsdatum: 2006-02-14
    Beschreibung: A joint NASA/USAF program was conducted to accomplish the following objectives: (1) evaluate the benefits that could be achieved from the application of winglets to KC-135 aircraft; and (2) determine the ability of wind tunnel tests and analytical analysis to predict winglet characteristics. The program included wind-tunnel development of a test winglet configuration; analytical predictions of the changes to the aircraft resulting from the application of the test winglet; and finally, flight tests of the developed configuration. Pressure distribution, loads, stability and control, buffet, fuel mileage, and flutter data were obtained to fulfill the objectives of the program.
    Schlagwort(e): AERODYNAMICS
    Materialart: KC-135 Winglet Program Rev.; p 1-46
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  • 5
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    KC-135 wing and winglet flight pressure distributions, loads, and wing deflection results with some wind tunnel comparisons (1982)
    In:  CASI
    Details
    Publikationsdatum: 2006-02-14
    Beschreibung: A full-scale winglet flight test on a KC-135 airplane with an upper winglet was conducted. Data were taken at Mach numbers from 0.70 to 0.82 at altitudes from 34,000 feet to 39,000 feet at stabilized flight conditions for wing/winglet configurations of basic wing tip, 15/-4 deg, 15/-2 deg, and 0/-4 deg winglet cant/incidence. An analysis of selected pressure distribution and data showed that with the basic wing tip, the flight and wind tunnel wing pressure distribution data showed good agreement. With winglets installed, the effects on the wing pressure distribution were mainly near the tip. Also, the flight and wind tunnel winglet pressure distributions had some significant differences primarily due to the oilcanning in flight. However, in general, the agreement was good. For the winglet cant and incidence configuration presented, the incidence had the largest effect on the winglet pressure distributions. The incremental flight wing deflection data showed that the semispan wind tunnel model did a reasonable job of simulating the aeroelastic effects at the wing tip. The flight loads data showed good agreement with predictions at the design point and also substantiated the predicted structural penalty (load increase) of the 15 deg cant/-2 deg incidence winglet configuration.
    Schlagwort(e): AERODYNAMICS
    Materialart: KC-135 Winglet Program Rev.; p 47-102
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  • 6
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    Status of advanced airfoil tests in the Langley 0.3-meter transonic cryogenic tunnel (1984)
    In:  CASI
    Details
    Publikationsdatum: 2006-02-14
    Beschreibung: A joint NASA/U.S. industry program to test advanced technology airfoils in the Langley 0.3-meter Transonic Tunnel (TCT) was formulated under the Langley ACEE Project Office. The objectives include providing U.S. industry an opportunity to compare their most advanced airfoils to the latest NASA designs by means of high Reynolds number tests in the same facility. At the same time, industry would again experience in the design and construction of cryogenic test techniques. The status and details of the test program are presented. Typical aerodynamic results obtained, to date, are presented at chord Reynolds number up to 45 x 10(6) and are compared to results from other facilities and theory. Details of a joint agreement between NASA and the Deutsche Forschungs- und Versuchsantalt fur Luft- and Raumfahrt e.V. (DFVLR) for tests of two airfoils are also included. Results of these tests will be made available as soon as practical.
    Schlagwort(e): AERODYNAMICS
    Materialart: Advan. Aerodyn.: Selected NASA Res.; p 37-53
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  • 7
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    Thermal control coatings experiment (A0138-6) (1984)
    In:  CASI
    Details
    Publikationsdatum: 2006-02-14
    Beschreibung: The objectives of this LDEF experiment are to verify the validity of space environment simulation performed in the laboratory in order to measure the stability of the thermo-optical properties of thermal control coatings, and to compare the behavior in space of some materials for which the available ultraviolet solar simulation is inadequate (especially in the far ultraviolet). The experimental approach is to passively expose samples of the thermal coatings of interest. These coatings include black paint, aluminum paint, white paint, a solar absorber, an optical surface reflector, second surface mirrors, metal coatings, and silica fabrics. Preflight and postflight measurements of thermo-optical properties will be compared to determine the effects of space environment exposure.
    Schlagwort(e): NONMETALLIC MATERIALS
    Materialart: NASA. Langley Research Center Long Duration Exposure Facility (LDEF); p 52-53
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  • 8
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    Atomic-oxygen stimulated outgassing (A0034) (1984)
    In:  CASI
    Details
    Publikationsdatum: 2006-02-14
    Beschreibung: The objective of this experiment is to determine if the impingement of atomic oxygen in near-Earth orbit is a major factor in producing optically damaging outgassed products. The expected results will be to obtain samples which have been exposed to atomic oxygen for long durations. Analysis of these samples will determine if the impingement of atomic oxygen on the thermal control surfaces stimulates a significant amount of outgassed products. This experiment will give a clearer picture of the contamination problem and will assist in assuring that future Shuttle payloads, such as the Space Telescope and High-Energy Astronomy Observatory, will not experience Skylab contamination levels. Selected thermal control surfaces will be exposed to the atomic oxygen in near-Earth orbit. Passive collecting samples will collect any induced outgassing resulting from oxygen impingement. The optical condition of the passive samples will be measured using a ground-based integrating sphere reflectometer and a directional reflectometer.
    Schlagwort(e): NONMETALLIC MATERIALS
    Materialart: NASA. Langley Research Center Long Duration Exposure Facility (LDEF); p 11-13
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  • 9
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    Shuttle tile environments and loads (1982)
    In:  CASI
    Details
    Publikationsdatum: 2006-02-14
    Beschreibung: The Shuttle tile ascent environments are discussed and the procedures used to convert these environments into tile loads are outlined. Testing which was performed to quantify or verify the loads are discussed, along with the load combination rationale which was used. The discussion of the ascent environment is limited to the transonic/supersonic portion of the mission since mechanical design loads occur during this time, and to specific regions of the vehicle, in particular those regions in which undensified critical (black) tiles are located.
    Schlagwort(e): NONMETALLIC MATERIALS
    Materialart: Shock and Vibration Inform. Center The Shock and Vibration Bull., No. 52. Part 2; p 111-125
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  • 10
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    Structural characteristics of the shuttle orbiter ceramic thermal protection system (1982)
    In:  CASI
    Details
    Publikationsdatum: 2006-02-14
    Beschreibung: The thermal protection system (TPS) of the Space Shuttle Orbiter is described as well as the results of dynamic reponse studies conducted in support of the efforts to certify the TPS for flight. The ceramic Thermal Protection System consists of ceramic tiles bonded to felt pads which are in turn bonded to the Orbiter substructure to protect the aluminum substructure from the heat of reentry.
    Schlagwort(e): NONMETALLIC MATERIALS
    Materialart: Shock and Vibration Inform. Center The Shock and Vibration Bull., No. 52. Part 2; p 101-110
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  • 11
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    Fibrous ceramic insulation (1982)
    In:  CASI
    Details
    Publikationsdatum: 2006-04-12
    Beschreibung: Some of the reusable heat shielding materials used to protect the Space Shuttles, their manufacturing processes, properties, and applications are discussed. Emphases is upon ceramic materials. Space Shuttle Orbiter tiles are discussed.
    Schlagwort(e): NONMETALLIC MATERIALS
    Materialart: NASA. Langley Research Center Advan. Mater. Technol.; p 261-274
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  • 12
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    Polymer research at NASA Langley Research Center (1982)
    In:  CASI
    Details
    Publikationsdatum: 2006-04-12
    Beschreibung: Polymer synthesis programs involve the development of Novel thermoplastics, pseudothermoplastics, and thermosets. These systems are prepared to elucidate structure-property relationships involving thermal capabilities, toughness, processability and environmental stability. Easily processable polyimides, solvent-resistant polysulfones and polyphenylquinoxalines, and tougher high and intermediate temperature polymers were developed. Characterization efforts included high pressure liquid chromatography methodology, the development of toughness tests for fiber reinforced composites, a study of electrical properties of metal ion filled polyimides, and a study of the mutagenicity of aromatic diamines. Also the mechanism of cure/degradation of experimental polymers was studied by rheology, mechanical behavior, separation techniques and spectroscopy. The degradative crosslinking of alkyl-containing polyimides, the separation and identification of crosslinked phenylquinoxalines, the rheological behavior of hot-melt polyimides, and the elucidation of the cure of norbornene endcapped imides were also studied.
    Schlagwort(e): NONMETALLIC MATERIALS
    Materialart: Advan. Mater. Technol.; p 29-48
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  • 13
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    Polymer materials research at NASA Ames Research Center (1982)
    In:  CASI
    Details
    Publikationsdatum: 2006-04-12
    Beschreibung: Polymers that provide significant improvements in both efficiency and safety for civilian transport aircraft and military combat aircraft were developed. High strength to weight structures such as carbon fiber composites with long term durability are requirements common to both classes of aircraft. Aircraft safety improvements in fire resistance and crashworthiness of primary and secondary structures are long term objectives for transport aircraft. Void filler ballistic foams, intumescent coatings, and radiation-resistant transparent plastics contribute to vulnerability reduction in combat military aircraft. Low and high velocity impact tolerance, fire resistance, thermal stability, and long term durability of polymers and components are emphasized.
    Schlagwort(e): NONMETALLIC MATERIALS
    Materialart: NASA. Langley Research Center Advan. Mater. Technol.; p 49-64
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  • 14
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    Component testing for dynamic model verification (1984)
    In:  CASI
    Details
    Publikationsdatum: 2006-02-14
    Beschreibung: Dynamic model verification is the process whereby an analytical model of a dynamic system is compared with experimental data, adjusted if necessary to bring it into agreement with the data, and then qualified for future use in predicting system response in a different dynamic environment. These are various ways to conduct model verification. The approach taken here employs Bayesian statistical parameter estimation. Unlike curve fitting, whose objective is to minimize the difference between some analytical function and a given quantity of test data (or curve), Bayesian estimation attempts also to minimize the difference between the parameter values of that funciton (the model) and their initial estimates, in a least squares sense. The objectives of dynamic model verification, therefore, are to produce a model which: (1) is in agreement with test data; (2) will assist in the interpretation of test data; (3) can be used to help verify a design; (4) will reliably predict performance; and (5) in the case of space structures, will facilitate dynamic control.
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA. Langley Research Center Recent Experiences in Multidisciplinary Analysis and Optimization, Part 2; 15 p
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  • 15
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    Post and a random-walk search mode (1984)
    In:  CASI
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    Publikationsdatum: 2006-02-14
    Beschreibung: Multidisciplinary analysis often requires optimization of nonlinear systems that are subject to constraints. Trajectory optimization is one example of this situation. The Program to Optimize Simulated Trajectories (POST) was used successfully for a number of problems. The purpose is to describe POST and a new optimization approach that has been incorporated into it. Typical uses of POST will also be illustrated. The projected-gradient approach to optimization is the preferred option in POST and is discussed. A new approach to optimization, the random-walk approach, is described, and results with the random-walk approach are presented.
    Schlagwort(e): AERODYNAMICS
    Materialart: Recent Experiences in Multidisciplinary Analysis and Optimization, Part 2; 23 p
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  • 16
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    Corrosion properties of second-generation conductive materials (1984)
    In:  CASI
    Details
    Publikationsdatum: 2006-02-14
    Beschreibung: Since the introduction of silver-filled epoxy adhesives and silver-filled nitrocellulose lacquer as RFI control materials, a number of new materials have been introduced. The resin carriers have been changed in an effort to make the materials more usable or more EPA acceptable and the fillers have been varied in an effort to make the materials less costly. The corrosion-related properties of second-generation materials were assessed, including adhesives, caulks, and greases. Aluminum 2024 was used as the only substrate material. Ten days of salt fog was used as the corrosive environment. If a noble material such as silver, nickel, or carbon is sandwiched with aluminum an increase in dc resistance results given enough time. If this is unsatisfactory electrically it should either not be used or have all corrosive environments excluded.
    Schlagwort(e): NONMETALLIC MATERIALS
    Materialart: NASA. Langley Research Center Intern. Aerospace and Ground Conf. on Lightning and Static Elec.; 7 p
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  • 17
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    Wall interference measurements for three-dimensional models in transonic wind tunnels: Experimental difficulties (1984)
    In:  CASI
    Details
    Publikationsdatum: 2006-02-14
    Beschreibung: The purpose is not to provide a detailed discussion of several wall interference experiments, but rather to use these experiments (recently accomplished in the Boeing Transonic Wind Tunnel (BTWT) to illustrate the problems associated with many of the measurements required by current wall interference assessment/correction (WIAC) procedures. The wall correction to lift is emphasized. It is shown that, because conventional tunnels and relatively small models continue to be used, the flow field or flow boundary measurements to be made impose severe requirements on the experiment itself. In some cases, existing instrumentation and test techniques may not be adequate to obtain the data accuracies needed.
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA. Langley Research Center Wind Tunnel Wall Interference Assessment and Correction, 1983; p 21-42
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  • 18
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    Adaptation of a four-wall interference assessment/correction procedure for airfoil tests in the 0.3-m TCT (1984)
    In:  CASI
    Details
    Publikationsdatum: 2006-02-14
    Beschreibung: Based upon limited, initial observations of wall interference corrections obtained for one airfoil test, there is a need for assessing the upstream flow direction. If there is no direct measurement then a two-pass correction procedure similar to the one described here is required. Questions have arisen pertaining to the correct interpretation of the pressure coefficients measured on the slats of a slotted tunnel wall, the interpretation of just what the calculated equivalent body encompasses or should include, and what can or should be considered as quantitative criteria for data correctability. Further studies using this modified procedure will address these questions. Hopefully, a meaningful WIAC procedure can be validated for the airfoil tests in the 0.3-m TCT.
    Schlagwort(e): AERODYNAMICS
    Materialart: Wind Tunnel Wall Interference Assessment and Correction, 1983; p 393-414
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  • 19
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    Some experience with Barnwell-Sewall type correction to two-dimensional airfoil data (1984)
    In:  CASI
    Details
    Publikationsdatum: 2006-02-14
    Beschreibung: A series of airfoils were tested in the Langley 0.3-Meter Transonic Cryogenic Tunnel (TCT) at Reynolds numbers from 2 to 50 million. The 0.3-m TCT is equipped with Barnwell slots designed to minimize blockage due to the tunnel flow and ceiling. This design suggests that sidewall corrections for blockage is needed, and that a lifting airfoil produces a change in angle of attack. Sidewall correction methods were developed for subsonic and subsonic-transonic flow. Comparisons of theory with experimental data obtained in the 0.3-m TCT for two airfoils, the British NPL 9510 and the German R-4 are presented. The NPL 9510 was tested as part of the NASA/United Kingdom Joint Aeronautical Program and R-4 was tested as part f the DFVLR/NASA Advanced Airfoil Research Program. For the NPL 9510 airfoil, only those test points that one would anticipate being difficult to predict theoretically are presented.
    Schlagwort(e): AERODYNAMICS
    Materialart: Wind Tunnel Wall Interference Assessment and Correction, 1983; p 375-392
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  • 20
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    Experiences with a high-blockage model tested in the NASA Ames 12-foot pressure wind tunnel (1984)
    In:  CASI
    Details
    Publikationsdatum: 2006-02-14
    Beschreibung: Representation of the flow around full-scale ships was sought in the subsonic wind tunnels in order to a Hain Reynolds numbers as high as possible. As part of the quest to attain the largest possible Reynolds number, large models with high blockage are used which result in significant wall interference effects. Some experiences with such a high blockage model tested in the NASA Ames 12-foot pressure wind tunnel are summarized. The main results of the experiment relating to wind tunnel wall interference effects are also presented.
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA. Langley Research Center Wind Tunnel Wall Interference Assessment and Correction, 1983; p 345-360
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  • 21
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    An inerference assessment approach for a three-dimensional slotted tunnel with sparse wall pressure data (1984)
    In:  CASI
    Details
    Publikationsdatum: 2006-02-14
    Beschreibung: The various procedures referred to as wall interference assessment and correction procedures presume the existence of a surface distribution of data (usually static pressure) measured over a surface on or near the tunnel walls for each test point to be assessed. An alternative approach in which a reasonably sophisticated computer model of the test section flow would be fitted parametrically to a sparse set of measured data is presented. The measurements provides line distributions of static pressure near the center lines of the top, side and bottom walls. The development of a test section model incorporating explicit recognition of discrete slots of finite length with controlled flow reentry into the solid wall downstream portion of the tunnel is shown.
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA. Langley Research Center. Wind Tunnel Wall Interference Assessment and Correction, 1983; p 323-334
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  • 22
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    Synthesis of aminosilane and aromatic diamine intermediates for polymerization (1982)
    In:  CASI
    Details
    Publikationsdatum: 2006-02-14
    Beschreibung: The preparation of monomers for use in a study to improve properties of epoxy polymers and silicone elastomers is described. Various approaches to the solution of the synthesis of aminosilane and diamine curing agents were examined. Ortho-, meta-, and para-substituted diamines where X is CH2, C(CH3)2, O, S, NH, or SO2 and n = 0, 1, 2, and 3 were investigated.
    Schlagwort(e): NONMETALLIC MATERIALS
    Materialart: The 1981 NASA(ASEE Summer Fac. Fellowship Program; 9 p
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  • 23
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    Development of high strength, high temperature ceramics (1982)
    In:  CASI
    Details
    Publikationsdatum: 2006-02-14
    Beschreibung: Improvement in the high-pressure turbopumps, both fuel and oxidizer, in the Space Shuttle main engine were considered. The operation of these pumps is limited by temperature restrictions of the metallic components used in these pumps. Ceramic materials that retain strength at high temperatures and appear to be promising candidates for use as turbine blades and impellers are discussed. These high strength materials are sensitive to many related processing parameters such as impurities, sintering aids, reaction aids, particle size, processing temperature, and post thermal treatment. The specific objectives of the study were to: (1) identify and define the processing parameters that affect the properties of Si3N4 ceramic materials, (2) design and assembly equipment required for processing high strength ceramics, (3) design and assemble test apparatus for evaluating the high temperature properties of Si3N4, and (4) conduct a research program of manufacturing and evaluating Si3N4 materials as applicable to rocket engine applications.
    Schlagwort(e): NONMETALLIC MATERIALS
    Materialart: Alabama Univ. in Huntsville The 1981 NASA(ASEE Summer Fac. Fellowship Program; 11 p
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  • 24
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    Development of toughened epoxy polymers for high performance composite and ablative applications (1982)
    In:  CASI
    Details
    Publikationsdatum: 2006-02-14
    Beschreibung: A survey of current procedures for the assessment of state of cure in epoxy polymers and for the evaluation of polymer toughness as related to nature of the crosslinking agent was made to facilitate a cause-effect study of the chemical modification of epoxy polymers. Various conformations of sample morphology were examined to identify testing variables and to establish optimum conditions for the selected physical test methods. Dynamic viscoelasticity testing was examined in conjunction with chemical analyses to allow observation of the extent of the curing reaction with size of the crosslinking agent the primary variable. Specifically the aims of the project were twofold: (1) to consider the experimental variables associated with development of "extent of cure" analysis, and (2) to assess methodology of fracture energy determination and to prescribe a meaningful and reproducible procedure. The following is separated into two categories for ease of presentation.
    Schlagwort(e): NONMETALLIC MATERIALS
    Materialart: Alabama Univ. in Huntsville The 1981 NASA(ASEE Summer Fac. Fellowship Program; 17 p
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  • 25
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    Interference from slotted walls (1984)
    In:  CASI
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    Publikationsdatum: 2006-02-14
    Beschreibung: Wall interference is made predominant in tunnel models and by wall geometries to facilitate the study of slot flow. The viscous effects in slots are studied by two dimensional measurements of flow. Wall interference is assessed by measuring pressure distributions at two levels near the walls. Interference on lifting delta wings is calculated. Pressure distributions at inner boundaries show basis axisymetries between the pressure side and the suction side, pointing to the necessity of having wider slots on the pressure side.
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA. Langley Research Center Wind Tunnel Wall Interference Assessment and Correction, 1983; p 293-300
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  • 26
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    Development in UK of a method for calculating tunnel wall corrections from flow measurements (1984)
    In:  CASI
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    Publikationsdatum: 2006-02-14
    Beschreibung: Classical methods for calculation of wall corrections which are not satisfactory for a number of flows of interest are discussed. To meet these objections, a number of methods were developed which use measurements of the low at or close to the tunnel walls as an outer boundary condition to define wall interference. The development, assessment and application of one such method is summarized.
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA. Langley Research Center Wind Tunnel Wall Interference Assessment and Correction, 1983; p 259-271
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  • 27
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    NLR activities in the field of wind tunnel wall interference (1984)
    In:  CASI
    Details
    Publikationsdatum: 2006-02-14
    Beschreibung: Measured field data as a boundary condition for calculating the interference flow field were applied. They are divided into two categories. In the first category, the field data must consist of distributions of a single velocity component, and an accurate estimate of the hypothetical free air contribution of the model to this component is required. The differences between measured values and estimated model contributions are attributed to wall interference and they establish the boundary condition. The associated field data measurements are simple, yet the necessary model representation generally is a serious drawback. The second category requires field data which consist of velocity vector distributions at the price of multicomponent measurements, but at the profit that no information at all is required about the model. In solid wall test sections, the price is reduced to virtually zero but the profit remains.
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA. Langley Research Center Wind Tunnel Wall Interference Assessment and Correction, 1983; p 221-229
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  • 28
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    Performance of two transonic airfoil wind tunnels utilizing limited ventilation (1984)
    In:  CASI
    Details
    Publikationsdatum: 2006-02-14
    Beschreibung: A limited-zone ventilated wall panel was developed for a closed-wall icing tunnel which permitted correct simulation of transonic flow over model rotor airfoil sections with and without ice accretions. Candidate porous panels were tested in the Ohio State University 6- x 12-inch transonic airfoil tunnel and result in essentially interference-free flow, as evidenced by pressure distributions over a NACA 0012 airfoil for Mach numbers up to 0.75. Application to the NRC 12- x 12-inch icing tunnel showed a similar result, which allowed proper transonic flow simulation in that tunnel over its full speed range.
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA. Langley Research Center Wind Tunnel Wall Interference Assessment and Correction, 1983; p 165-170
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  • 29
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    Investigations of flow field perturbations induced on slotted transonic-tunnel walls (1984)
    In:  CASI
    Details
    Publikationsdatum: 2006-02-14
    Beschreibung: The free-stream interference caused by the flow through the slotted walls of the test sections of transonic wind tunnels has continuously a problem in transonic tunnel testing. The adaptive-wall transonic tunnel is designed to actively control the near-wall boundary conditions by sucking or blowing through the wall. In order to make the adaptive-wall concept work, parameters for computational boundary conditions must be known. These parameters must be measured with sufficient accuracy to allow numerical convergence of the flow field computations and must be measured in an inviscid region away from the model that is placed inside the wind tunnel. The near-wall flow field was mapped in detail using a five-port cone probe that was traversed in a plane transverse to the free-stream flow. The initial experiments were made using a single slot and recent measurements used multiple slots, all with the tunnel empty. The projection of the flow field velocity vectors on the transverse plane revealed the presence of a vortex-like flow with vorticity in the free stream. The current research involves the measurement of the flow field above a multislotted system with segmented plenums behind it, in which the flow is controlled through several plenums simultaneously. This system would be used to control a three-dimensional flow field.
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA. Langley Research Center Wind Tunnel Wall Interference Assessment and Correction, 1983; p 119-142
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  • 30
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    Assessment of lift- and blockage-induced wall interference in a three-dimensional adaptive-wall tunnel (1984)
    In:  CASI
    Details
    Publikationsdatum: 2006-02-14
    Beschreibung: A three-dimensional adaptive-wall wind tunnel experiment was conducted at Ames Research Center. This experiment demonstrated the effects of wall interference on the upwash distribution on an imaginary surface surrounding a lifting wing. This presentation demonstrates how the interference assessment procedure used in the adaptive-wall experiments to determine the wall adjustments can be used to separately assess lift- and blockage-induced wall interference in a passive-wall wind tunnel. The effects of lift interference on the upwash distribution and on the model lift coefficient are interpreted by a simple horseshoe vortex analysis.
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA. Langley Research Center Wind Tunnel Wall Interference Assessment and Correction, 1983; p 89-100
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  • 31
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    Wind tunnel wall interference in closed, ventilated and adaptive test sections (1984)
    In:  CASI
    Details
    Publikationsdatum: 2006-02-14
    Beschreibung: A wall interference correction method for closed rectangular test sections was developed which uses measured wall pressures. Measurements with circular discs for blockage and a rectangular wing as a lift generator in a square closed test section validate this method. These measurements are intended to be a basis of comparison for measurements in the same tunnel using ventilated (in these case, slotted) walls. Using the vortex lattice method and homogeneous boundary conditions, calculations were performed which show sufficiently high pressure levels at the walls for correction purposes in test sections with porous walls. In Gottingen, an adaptive test section (which is a deformable rubber tube of 800 mm diameter) was built and a computer program was developed which is able to find the necessary wall adaptation for interference-free measurements in a single step. To check the program prior to the first run, the vortex lattice method was used to calculate wall pressure distributions in the nonadapted test section as input data for the one-step method. Comparison of the pressure distribution in the adapted test section with free-flight data shows nearly perfect agreement. An extension of the computer program can be made to evaluate the remaining interference corrections.
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA. Langley Research Center Wind Tunnel Wall Interference Assessment and Correction, 1983; p 61-78
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  • 32
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    Review of the advanced technology airfoil test program in the 0.3-meter transonic cryogenic tunnel (1984)
    In:  CASI
    Details
    Publikationsdatum: 2006-02-14
    Beschreibung: The following areas were addressed: interchangeable test sections in the 0.3-M Transonic Cryogenic Tunnel (TCT); typical airfoil installation; airfoil capability; advanced technology airfoil test (ATAT); effects of the Reynolds number on the normal force coefficient; effects of the Reynolds number on the drag coefficient; and comparison of experimental results with theory.
    Schlagwort(e): AERODYNAMICS
    Materialart: Wind Tunnel Wall Interference Assessment and Correction, 1983; p 361-374
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  • 33
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    Determination of equivalent model geometry for tunnel wall interference assessment/correction (1984)
    In:  CASI
    Details
    Publikationsdatum: 2006-02-14
    Beschreibung: A formula for the determination of equivalent model geometry with two variables measured at the interface is derived, based on two dimensional subsonic flow. This predicted model profile is a reasonable initial estimate for transonic flow as long as the sonic region does not reach the interface. A general formula is given in two forms. One is in terms of complex variable functions and the other is an integral equation. The complex-function formula has the advantage of using analytic expressions. The integral equation form requires a numerical solution after assuming the model geometry as a polynomial function. Examples are given to illustrate the application of the formulas.
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA. Langley Research Center Wind Tunnel Wall Interference Assessment and Correction, 1983; p 335-342
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  • 34
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    An analytic solution to the classical two-body problem with drag (1981)
    In:  CASI
    Details
    Publikationsdatum: 2006-02-14
    Beschreibung: The two body problem was analyzed with a specific drag model. The model treats drag as a force proportional to the vector velocity and inversely proportional to the distance to the center of attraction. The solution is expressed in terms of known functions and is of a simple and compact form. The time of flight is expressed as a quadrature in the true anomaly. The results are: (1) development of a vector differential equation which allows analysis of an infinite number of gravitational and drag models; and (2) obtaining the solution of a linear differential equation using the inverse method of laplace transforms.
    Schlagwort(e): AERODYNAMICS
    Materialart: Houston Univ. The 1981 NASA ASEE Summer Fac. Fellowship Program, Vol. 2; 22 p
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  • 35
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    Wind tunnel wall interference correction for aircraft models (1984)
    In:  CASI
    Details
    Publikationsdatum: 2006-02-14
    Beschreibung: Wall interference correction procedures seek to determine the required changes in certain flow or geometric parameters so that the difference between the flow properties at the model's surface in the tunnel and free air are minimized. A transonic and a linear correction procedure were developed for aircraft models. In addition to Mach number and angle of attack corrections, an estimate of the accuracy of the corrections is provided by the transonic correction procedure. Lift, pitching moment and pressure measurements near the tunnel walls are required. The efficiency and accuracy of the correction procedure are improved. Moreover, correction of both the wing and tail angles of attack is allowed. The procedure is valid for transonic as well as subcritical flows. However, for subcritical flows further approximations and simplifying assumptions are made, leading to a very simple and efficient correction procedure.
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA. Langley Research Center. Wind Tunnel Wall Interference Assessment and Correction, 1983; p 301-322
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  • 36
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    Tunnel constraint for a jet in crossflow (1984)
    In:  CASI
    Details
    Publikationsdatum: 2006-02-14
    Beschreibung: A facet of a unified tunnel correction scheme which uses wall pressures to determine tunnel induced blockage and upwash is described. With this method, there is usually no need to use data concerning model forces or power settings to find the interference; it follows directly from the pressures and tunnel dimensions. However, highly inclined jets do not produce good pressure signatures and are highly three dimensional, so they must be treated differently. Flow modeling is also discussed.
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA. Langley Research Center. Wind Tunnel Wall Interference Assessment and Correction, 1983; p 273-290
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  • 37
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    Progress in wind tunnel wall interference assessment/correction procedures at the NAE (1984)
    In:  CASI
    Details
    Publikationsdatum: 2006-02-14
    Beschreibung: Wall corrections as a function of wall porosity in the transonic wall interference problem was assessed. Effective porosities primarily for the two dimensional case were established as follows: (1) comparison of experimental data for two geometrically similar models of different chord/height ratio, an overall value of wall porosity could be deduced; (2) theoretical development which allows for unequal porosity for the floor and ceiling and wall boundary pressure measurements, porosities for floor and ceiling could be deduced; (3) a scheme was developed which allowed unequal porosity of floor and ceiling and streamwise varying porosity. The boundary layer development along the perforated floor and ceiling under the influence of the model pressure field, variations in boundary layer thickness underlining the difficulties in deducing meaningful values of wall porosity were determined. Wall boundary pressure measurement, in combination with singularity modelling of the airfoil, was sufficient to yield required information on the wall interference flow without having to establish some value for wall porosity. The singularity modelling of the airfoil initially covered only lift and volume but was extended to include drag and pitching moment, and second order volume term. It is shown by asymptotic transonic small disturbance analysis, that the derived corrections to angle of attack and free stream Mach number are correct to the first order.
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA. Langley Research Center Wind Tunnel Wall Interference Assessment and Correction, 1983; p 231-257
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  • 38
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    Asymptotic methods for wind tunnel wall corrections at transonic speed (1984)
    In:  CASI
    Details
    Publikationsdatum: 2006-02-14
    Beschreibung: The effort to develop classical methods to compute wall interference at transonic speeds is outlined. The two-dimensional theory and three-dimensional development are discussed. Also, some numerical application of the two-dimensional work are indicated. The basic advantages of the asymptotic theory are noted.
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA. Langley Research Center Wind Tunnel Wall Interference Assessment and Correction, 1983; p 193-203
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  • 39
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    Effect of boundary layers on solid walls in three-dimensional subsonic wind tunnels (1984)
    In:  CASI
    Details
    Publikationsdatum: 2006-02-14
    Beschreibung: A solution for the tunnel wall boundary layer effects for three-dimensional subsonic tunnels is presented. The model potentials are represented with simple singularities placed on the centerline of the tunnel and Laplace's equation in cylindrical coordinates is solved for either the conventional homogeneous slotted-wall boundary condition, the solid-wall viscous boundary condition, or a combination of them. The most pronounced wall boundary layer effect is on solid blockage for completely closed wind tunnels. Boundary layers on the wall reduce the blockage from the solid-wall, no-boundary-layer case in a manner similar to opening slots in a solid wall. Additionally, for solid-wall tunnel configurations, the streamline curvature interference factor is reduced by a significant amount, whereas the lift interference factor at the model station does not depend on the boundary layer parameter. For combination wall configurations, the slot effect of the horizontal walls dominates the viscous effect of the solid sidewalls.
    Schlagwort(e): AERODYNAMICS
    Materialart: Wind Tunnel Wall Interference Assessment and Correction, 1983; p 205-218
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  • 40
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    Experiments suitable for wind tunnel wall interference assessment/correction (1984)
    In:  CASI
    Details
    Publikationsdatum: 2006-02-14
    Beschreibung: Three experiments suitable for wall interference assessment and evaluation of proposed correction methods are presented. The experiments are: (1) a series of airfoil tests using a newly designed transonic flow facility that employs side-wall boundary layer suction and upper- and lower-wall shaping; (2) tests on a swept airfoil section spanning a solid-wall wind tunnel with fixed contouring on all four walls; and (3) tests on a swept wing of aspect ratio 3 mounted in a solid-wall wind tunnel with fixed flat walls. Each of the experiments provides data on the airfoil sections as well as on the wind tunnel walls. All the experiments were performed in solid wall wind tunnels corrected for boundary layer displacement effects. Although the experiments were performed primarily to evaluate computer code performance, it is believed that they also provide information that can be used to evaluate methods for assessing and correcting wall interference effects.
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA. Langley Research Center Wind Tunnel Wall Interference Assessment and Correction, 1983; p 171-190
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  • 41
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    Effect of upstream sidewall boundary layer removal on an airfoil test (1984)
    In:  CASI
    Details
    Publikationsdatum: 2006-02-14
    Beschreibung: Sidewall boundary layer effects were investigated by applying partial upstream sidewall boundary layer removal in the Langley 0.3-m transonic cryogenic tunnel. Over the range of sidewall boundary layer displacement thickness of these tests the influence on pressure distribution was found to be small for subcritical conditions; however, for supercritical conditions the shock position was affected by the sidewall boundary layer. For these tests (with and without boundary layer remove) comparisons with predictions of the GRUMFOIL computer code indicated that Mach number corrections due to the sidewall boundary layer improve the agreement for both subcritical and supercritical conditions. The results also show that sidewall boundary layer removal reduces the magnitude of the sidewall correction; however, a suitable correction must still be made.
    Schlagwort(e): AERODYNAMICS
    Materialart: Wind Tunnel Wall Interference Assessment and Correction, 1983; p 143-163
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  • 42
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    A data base for three-dimensional all-interference code evaluation (1984)
    In:  CASI
    Details
    Publikationsdatum: 2006-02-14
    Beschreibung: A validation of a measured boundary condition technique was carried out to demonstrate the feasibility of a wall interference assessment/correction (WIAC) system. An experimental evaluation was also carried out to compare performances of various techniques, to define the number of necessary boundary measurements for accurate assessment/corrections and to define the envelope of test conditions for which accurate assessment/corrections are achieved. The relative merits of a WIAC system and an adaptive wall tunnel are compared. The measurement surface boundary data is performed with a system of two rotating pipes. These pipes sweep out a cylindrical measurement surface near the tunnel walls, approximately one inch from the wall at the closest point. The experimental model was specially designed and fabricated for the adaptive wall experiments. The model is a wing/tail/body configuration with swept lifting surface. The boundary data taken in Tunnel 1T with the rotating pipe system has been shown to offer several attractive features for WIAC code evaluation. Good spatial resolution of measurements is achieved and measurements are made upstream and downstream of the model. Also, two velocity components are determined.
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA. Langley Research Center Wind Tunnel Wall Interference Assessment and Correction, 1983; p 101-118
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  • 43
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    Survey of ONERA activities on adaptive-wall applications and computation of residual corrections (1984)
    In:  CASI
    Details
    Publikationsdatum: 2006-02-14
    Beschreibung: The research undertaken concerning the computation and/or reduction of wall interference follows two main axes: improvement of wall correction determinations, and use of adaptive flexible walls. The use of wall-measured data to compute interference effects is reliable when the model representation is assessed by signatures with known boundary conditions. When the computed interferences are not easily applicable to correcting the results (especially for gradients in two-dimensional cases), the flexible adaptive walls in operation in T2 are an efficient and assessed means of reducing the boundary effects to a negligible level, if the direction and speed of the flow are accurately measured on the boundary. The extension of the use of adaptive walls to three-dimensional cases may be attempted since the residual corrections are assumed to be small and are computable.
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA. Langley Research Center Wind Tunnel Wall Interference Assessment and Correction, 1983; p 43-60
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  • 44
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    Langley high-lift research on a high-aspect-ratio supercritical wing configuration (1981)
    In:  CASI
    Details
    Publikationsdatum: 2006-02-14
    Beschreibung: To determine the low speed performance characteristics of a representative high aspect ratio supercritical wing, two low speed jet transport models were fabricated. A 12-ft. span model was used for low Reynolds number tests in the Langley 4- by 7-Meter Tunnel and the second, a 7.5-ft. span model, was used for high Reynolds number tests in the Ames 12-foot Pressure Tunnel. A brief summary of the results of the tests of these two models is presented and comparisons are made between the data obtained on these two models and other similar models. Follow-on two and three dimensional research efforts related to the EET high-lift configurations are also presented and discussed.
    Schlagwort(e): AERODYNAMICS
    Materialart: Advan. Aerodyn.: Selected NASA Res.; p 55-77
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  • 45
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    Measured transonic unsteady pressures on an energy efficient transport wing with oscillating control surfaces (1981)
    In:  CASI
    Details
    Publikationsdatum: 2006-02-14
    Beschreibung: Highlight results are presented from subsonic and transonic pressure measurement studies conducted in the Langley Transonic Dynamics Tunnel on a supercritical wing model representative of an energy efficient transport design. Steady- and unsteady-pressure data were acquired on the upper and lower wing surface at an off-design Mach number of 0.60 and at the design Mach number of 0.78, for a Reynolds number of 2.2 x 10(6) (based on the wing average chord). The model configuration consisted of a sidewall-Mounted half-body fuselage and a semi-span wing with an aspect ratio of 10.76, a leading-edge sweepback angle of 28.8 degrees, and supercritical airfoil sections. The wing is instrumented with 252 static pressure orifices and 164 dynamic pressure gages. Model test variables included wing angle of attack, control-surface mean deflection angle, control-surface oscillating deflection angle and frequency, and phasing between oscillating leading-edge and trailing-edge controls when used together.
    Schlagwort(e): AERODYNAMICS
    Materialart: Advan. Aerodyn.: Selected NASA Res.; p 21-36
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  • 46
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    Effects of solar radiation on glasses (1984)
    In:  CASI
    Details
    Publikationsdatum: 2006-02-14
    Beschreibung: The effects of solar radiation and space environment on glasses in space flight by exposing glass specimens to the space environment was determined. The occurrence of optical, mechanical, and chemical property changes was analyzed. The property changes of samples receiving differing cumulative solar radiation exposure are compared.
    Schlagwort(e): NONMETALLIC MATERIALS
    Materialart: NASA. Langley Research Center Long Duration Exposure Facility (LDEF); p 170-172
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  • 47
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    Ion-beam-textured and coated surfaces experiment (S1003) (1984)
    In:  CASI
    Details
    Publikationsdatum: 2006-02-14
    Beschreibung: The objective of this LDEF experiment is to measure the effects of exposure to the shuttle launch and near Earth space environments on the optical properties of ion beam textured high absorptance solar thermal control surfaces, the optical and electrical properties of ion beam sputtered conductive solar thermal control surfaces, and the weight loss of ion beam deposited oxide polymer films. The various types of surfaces to be tested include six major categories: (1) ion beam textured surfaces suitable for space solar thermal (solar concentration) application; (2) painted and/or state of the art solar thermal surfaces; (3) ion beam sputtered conductive coatings for thermal and space charge control (e.g., indium-oxide coated metalized FEP Teflon); (4) ion beam sputtered conductive coated solar sail materials for space charge control and cooling through emittance; (5) micrometeoroid sensitive samples whose optical properties change only as a result of micrometeoroid impact; and (6) Kapton coated with oxide polymer films to minimize oxygen degradation at near Earth orbit altitudes.
    Schlagwort(e): NONMETALLIC MATERIALS
    Materialart: NASA. Langley Research Center Long Duration Exposure Facility (LDEF); p 62-65
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  • 48
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    Thermal control surface experiment (S0069) (1984)
    In:  CASI
    Details
    Publikationsdatum: 2006-02-14
    Beschreibung: The objectives of this LDEF experiment are to determine the effects of the near Earth orbital environment and the Shuttle induced environment in spacecraft thermal control surfaces. Spectral reflectance measurements will be obtained and used to differentiate between different solid state damage mechanisms of environmental damage to separate the effects of contamination from those of natural environment damage, and for comparison and correlation with laboratory test data.
    Schlagwort(e): NONMETALLIC MATERIALS
    Materialart: NASA. Langley Research Center Long Duration Exposure Facility (LDEF); p 57-61
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  • 49
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    Exposure of spacecraft coatings (S0010) (1984)
    In:  CASI
    Details
    Publikationsdatum: 2006-02-14
    Beschreibung: The objectives of this LDEF experiment are to determine the effects of both the Shuttle-induced environment and the space radiation environment on selected sets of spacecraft thermal control coatings. The experimental approach is to passively expose samples of thermal control coatings to Shuttle-induced and space radiation environments and to return the samples for postflight evaluation and comparison with preflight measurements to determine the effects of the environmental exposure. Optical measurements of the samples will include total normal emittance and spectral reflectance. The experiment will utilize a 6 in. deep peripheral tray and an experiment exposure control canister (EECC). The EECC will provide protection for some of the samples against exposure to the launch and reentry environments. The EECC will be programmed to open about 2 weeks after LDEF deployment and close pior to LDEF retrieval by the Shuttle and reentry. Some samples will not be housed in the EECC and will be exposed to the Shuttle-induced environment during launch and reentry. Comparison of the data from these samples with data from samples in the EECC will yield information about possible contamination induced degradation effects.
    Schlagwort(e): NONMETALLIC MATERIALS
    Materialart: Long Duration Exposure Facility (LDEF); p 54-56
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  • 50
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    Balloon materials degradation (S1006) (1984)
    In:  CASI
    Details
    Publikationsdatum: 2006-02-14
    Beschreibung: The objective of this experiment is to assess the effects of long-term exposure of candidate balloon films, tapes, and lines to the hostile environment above the Earth's atmosphere. Degradation of mechanical and radiometric properties will be observed by a series of tests on exposed materials. The experiment is passive and will test candidate balloon films, tapes, and lines. The experiment will occupy one-third of a 3-in.-deep peripheral tray. Two additional identical sets of material will be prepared. The first set will be tested immediately and the second will be held in a controlled environment until the recovery of the samples placed on orbit. Tests will then be performed on this second set to determine any effects of aging. The specimens that are recovered from the Long Duration Exposure Facility will also be tested and the effects of long-duration exposure noted. In addition to these specimens, another set of specimens will be exposed at an accelerated exposure facility and the results will be compared with those of specimens exposed in situ.
    Schlagwort(e): NONMETALLIC MATERIALS
    Materialart: NASA. Langley Research Center Long Duration Exposure Facility (LDEF); p 49-51
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  • 51
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    Polymer matrix composites research at NASA Lewis Research Center (1982)
    In:  CASI
    Details
    Publikationsdatum: 2006-04-12
    Beschreibung: The in situ polymerization of monomer reactants (PMR) approach was demonstrated to be a powerful approach for solving many of the processing difficulties associated with the use of high temperature resistant polymers as matrix resins in high performance composites. The PMR-15 polyimide provides the best overall balance of processing characteristics and elevated temperature properties. The excellent properties and commercial availability of composite materials based on PMR-15 led to their acceptance as viable engineering materials. The PMR-15 composites are used to produce a variety of high quality structural components.
    Schlagwort(e): NONMETALLIC MATERIALS
    Materialart: NASA. Langley Research Center Advan. Mater. Technol.; p 65-90
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  • 52
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    Viscous wing code development: A 3-D viscid-inviscid interactive analysis (1983)
    In:  Other Sources
    Details
    Publikationsdatum: 2011-08-19
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA. Langley Research Center, Theoretical Aerodynamics Contractors' Workshop, Volume 2; p 607-63
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  • 53
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    Computation of separated flow on airfoils with the Grumfoil code (1983)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA. Langley Research Center, Theoretical Aerodynamics Contractors' Workshop, Volume 2; p 557-58
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  • 54
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    Analysis of airfoil transitional separation bubbles (1983)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA. Langley Research Center, Theoretical Aerodynamics Contractors' Workshop, Volume 2; p 539-55
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  • 55
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    Entropy effects and shock fitting in conical supersonic full potential flows (1983)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Schlagwort(e): AERODYNAMICS
    Materialart: NASA. Langley Research Center, Theoretical Aerodynamics Contractors' Workshop, Volume 2; p 461-49
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  • 56
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    Corrosion protection coating (1982)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Schlagwort(e): NONMETALLIC MATERIALS
    Materialart: NASA Technol. Appl. Team; p 40
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  • 57
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    Crystallization of fluorozirconate glasses (1984)
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    Publikationsdatum: 2011-08-19
    Beschreibung: The crystallization of a number of glasses of the fluorozirconate family has been studied (using powder X-ray diffraction and DSC) as a function of time and temperature of heating. The main crystalline phases were beta BaZrF6 and beta BaZr2F10. Stable and metastble transformations to the low-temperature alpha phases were also investigated. The size of crystallites in fully devitrified glasses was calculated (from line broadening of the X-ray diffraction peaks) to be about 60 nm.
    Schlagwort(e): NONMETALLIC MATERIALS
    Materialart: Materials Research Bulletin (ISSN 0025-5408); 19; 5, 19; 577-590
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  • 58
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    Viscous transonic flow computation over Space Shuttle configuration (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: A thin-layer Navier-Stokes code capable of predicting steady-state viscous flows is applied to the transonic flow over a Space Shuttle configuration. The code is written in the generalized coordinate system, and the grid-generation code of Fujii (1983) is used for the discretization of the flow field. The flow-field computation is done using the CRAY 1S computer at NASA Ames. The computed result is physically reasonable, even though no experimental data is available for the comparison purpose.
    Schlagwort(e): AERODYNAMICS
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  • 59
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    Ion beam deposition of amorphous carbon films with diamond like properties (1982)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: Carbon films were deposited on silicon, quartz, and potassium bromide substrates from an ion beam. Growth rates were approximately 0.3 micron/hour. The films were featureless and amorphous and contained only carbon and hydrogen in significant amounts. The density and carbon/hydrogen ratio indicate the film is a hydrogen deficient polymer. One possible structure, consistent with the data, is a random network of methylene linkages and tetrahedrally coordinated carbon atoms.
    Schlagwort(e): NONMETALLIC MATERIALS
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  • 60
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    Surface crystallization of a fluoride glass (1983)
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    Publikationsdatum: 2011-08-19
    Beschreibung: Growth of crystals on the surface of a Zr-Ba-La fluoride glass was observed by optical and scanning electron microscopy. Small, dark crystal nucleated rapidly and grew to a size of about 10 microns; then they stopped growing, and wrinkled regions emerged, covering the entire crystal surface.
    Schlagwort(e): NONMETALLIC MATERIALS
    Materialart: American Ceramic Society, Communications (ISSN 0002-7820); 66; C-132
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  • 61
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    Siloxane containing addition polyimides (1984)
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    Publikationsdatum: 2011-08-18
    Beschreibung: Addition polyimide oligomers have been synthesized from bis(gamma-aminopropyl) tetramethyldisiloxane and 3, 3', 4, 4'-benzophenonetetracarboxylic dianhydride using a variety of latent crosslinking groups as endcappers. The prepolymers were isolated and characterized for solubility (in amide, chlorinated and ether solvents), melt flow and cure properties. The most promising systems, maleimide and acetylene terminated prepolymers, were selected for detailed study. Graphite cloth reinforced composites were prepared and properties compared with those of graphite/Kerimid 601, a commercially available bismaleimide. Mixtures of the maleimide terminated system with Kerimid 601, in varying proportions, were also studied.
    Schlagwort(e): NONMETALLIC MATERIALS
    Materialart: SAMPE Quarterly (ISSN 0036-0821); 15; 24-30
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  • 62
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    Nonlinear aerodynamic effects on bodies in supersonic flow (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Schlagwort(e): AERODYNAMICS
    Materialart: Journal of Aircraft (ISSN 0021-8669); 21; 809-815
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  • 63
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    Thermoplastic composite matrices with improved solvent resistance (1984)
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    Publikationsdatum: 2011-08-18
    Beschreibung: In order to improve solvent resistance of aromatic thermoplastic polymers, ethynyl-terminated aromatic sulfone polymers (ETS), sulfone/ester polymers (SEPE) containing pendent ethynyl groups, and phenoxy resin containing pendent ethynyl groups are synthesized. Cured polysulfones and phenoxy resins containing ethynyl groups on the ends or pendent on the molecules exhibited systematic behavior in solvent resistance, film flexibility, and toughness as a function of crosslink density. The film and composite properties of a cured solvent-resistant ETS were better than those of a commercially available solvent sensitive polysulfone. The study was part of a NASA program to better understand the trade-offs between solvent resistance, processability and mechanical properties which may be useful in designing composite structures for aerospace vehicles.
    Schlagwort(e): NONMETALLIC MATERIALS
    Materialart: SAMPE Journal (ISSN 0091-1062); 20; 18-23
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  • 64
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    New implicit boundary procedures - Theory and applications (1984)
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    Publikationsdatum: 2011-08-18
    Beschreibung: Previously cited in issue 5, p. 579, Accession no. A83-16536
    Schlagwort(e): AERODYNAMICS
    Materialart: AIAA Journal (ISSN 0001-1452); 22; 1094-110
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  • 65
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    Numerical simulations of unsteady transonic flow in diffusers (1984)
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    Publikationsdatum: 2011-08-18
    Beschreibung: Previously cited in issue 15, p. 2346, Accession no. A82-31959
    Schlagwort(e): AERODYNAMICS
    Materialart: AIAA Journal (ISSN 0001-1452); 22; 1139-114
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  • 66
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    Polyimides formulated from a partially fluorinated diamine for aerospace tribological applications (1984)
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    Publikationsdatum: 2011-08-18
    Beschreibung: Preliminary pribological studies on polyimides formulated from the diamine 2,2-bis 4-(4-aminophenoxy)phenyl hexafluoropane (4-BDAF) indicate that polyimides formulated from this diamine have excellent potential for high temperature tribological applications. The dianhydrides used to make the polyimides were pyromellitic (PMDA) and benzophenonetetracarboxylic acid (BTDA). Friction and wear studies at 25 and 200 C indicate that polyimides formulated using 50 mole percent of the PMDA dianhydride and 50 mole percent of the BTDA dianhydride perform better than polyimides formulated solely with the BTDA dianhydride. Graphite fiber reinforced polyimide composites were formulated with the polyimide made from the BTDA dianhydride and both graphitic and non-graphitic fibers were evaluated. Graphitic fibers produced better tribological results, since thin, flowing, 'layer-like' transfer films were produced which did not build up with long sliding durations. Non-graphitic fibers did not produce this type of transfer. Previously announced in STAR as N83-22423
    Schlagwort(e): NONMETALLIC MATERIALS
    Materialart: ASLE Transactions; 27; 189-196
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  • 67
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    Effects of viscosity on transonic-aerodynamic and aeroelastic characteristics of oscillating airfoils (1984)
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    Publikationsdatum: 2011-08-18
    Schlagwort(e): AERODYNAMICS
    Materialart: Journal of Aircraft (ISSN 0021-8669); 21; 700-707
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  • 68
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    Leeside flows over delta wings at supersonic speeds (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Schlagwort(e): AERODYNAMICS
    Materialart: Journal of Aircraft (ISSN 0021-8669); 21; 680-686
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  • 69
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    Ceramic-coated metals can survive contact with hot working fluid (1984)
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    Publikationsdatum: 2011-08-18
    Beschreibung: Thermal barrier coatings (TBCs) have been developed as a means of protecting turbine blades and other engine hot section components whose surfaces are exposed to the most extreme operating conditions. By adding a thin, insulating ceramic oxide layer to an air-cooled turbine blade, the difference between the gas temperature and the metal temperature is further increased as a function of ceramic coating thickness, heat flux, and oxide thermal conductivity. An 0.04-cm thick ceramic layer can typically yield a 100-300 C temperature drop. Of the various techniques available for the deposition of thermal barrier coatings, the most common is that of plasma spraying. Significant improvements have been made in TBC durability through the use of bond coat compositions with increased oxidation resistance.
    Schlagwort(e): NONMETALLIC MATERIALS
    Materialart: Research and Development (ISSN 0160-4074); 26; 122-125
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  • 70
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    New phosphorus-containing bisimide resins (1984)
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    Publikationsdatum: 2011-08-18
    Beschreibung: Phosphorus-based flame retardants have been effectively used in a wide variety of polymeric materials. Such additives, however, may either influence the decomposition reaction in polymers or lack durability due to a tendency to be leached out by solvents. Attention is given to the synthesis, characterization, thermal stability and degradation mechanisms of bisimide resins, and an evaluation is conducted of the flammability and mechanical properties of graphite cloth-reinforced laminates fabricated from one of the six phosphorus-containing bisimide resins considered.
    Schlagwort(e): NONMETALLIC MATERIALS
    Materialart: IN: Contemporary topics in polymer science. Volume 4. New York; 115-139
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  • 71
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    Thermal oxidative degradation reactions of linear perfluoroalkyl ethers (1983)
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    Publikationsdatum: 2011-08-18
    Beschreibung: Thermal and thermal oxidative stability studies were performed on linear perfluoroalkyl ether fluids. The effect on degradation by metal catalysts and degradation inhibitors is reported. The linear perfluoroalkyl ethers are inherently unstable at 316 C in an oxidizing atmosphere. The metal catalysts greatly increased the rate of degradation in oxidizing atmospheres. In the presence of these metals in an oxidizing atmosphere, the degradation inhibitors were highly effective in arresting degradation at 288 C. However, the inhibitors had only limited effectiveness at 316 C. The metals promote degradation by chain scission. Based on elemental analysis and oxygen consumption data, the linear perfluoroalkyl ether fluids have a structural arrangement based on difluoroformyl and tetrafluoroethylene oxide units, with the former predominating. Previously announced in STAR as N82-26468
    Schlagwort(e): NONMETALLIC MATERIALS
    Materialart: I&EC - Industrial and Engineering Chemistry, Product Research and Development (ISSN 0196-4321); 22; 166-170
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  • 72
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    Fresh attack on laminar flow (1984)
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    Publikationsdatum: 2011-08-18
    Beschreibung: Laminar flow control is a technology with great potential for aircraft drag reduction. Stabilization of laminar boundary layers became known as natural laminar flow (NLF) and research led to the development of NLF airfoils. Research was also conducted on stabilization by suction, referred to as laminar flow control (LFC). Experiments demonstrated that extensive laminar flow could be achieved in flight. However, there remained doubts regarding the practicality of producing, with the technology then available, wing surfaces sufficiently smooth and wavefree to meet laminar-flow criteria and maintaining the wing surface quality in normal service. In 1976, the Aircraft Energy Efficiency (ACEE) program was begun by NASA to develop fuel-conservative technology for commercial transports. The progress of the ACEE program is discussed. Attention is given to LFC wing structures, and LFC leading-edge systems.
    Schlagwort(e): AERODYNAMICS
    Materialart: Aerospace America (ISSN 0740-722X); 22; 72-76
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  • 73
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    Space Shuttle heating analysis with variation in angle of attack and catalycity (1984)
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    Publikationsdatum: 2011-08-18
    Beschreibung: Previously cited in issue 5, p. 586, Accession no. A83-16747
    Schlagwort(e): AERODYNAMICS
    Materialart: Journal of Spacecraft and Rockets (ISSN 0022-4560); 21; 217-219
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  • 74
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    Large-area silicon sheet technology status in United States' Department of Energy photovoltaics programs (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Schlagwort(e): NONMETALLIC MATERIALS
    Materialart: International Journal of Solar Energy (ISSN 0142-5919); 2; 171-187
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  • 75
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    Fracture mechanics of cellular glass (1983)
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    Publikationsdatum: 2011-08-18
    Beschreibung: The fracture mechanics of cellular glasses (for the structural substrate of mirrored glass for solar concentrator reflecting panels) are discussed. Commercial and developmental cellular glasses were tested and analyzed using standard testing techniques and models developed from linear fracture mechanics. Two models describing the fracture behavior of these materials were developed. Slow crack growth behavior in cellular glass was found to be more complex than that encountered in dense glasses or ceramics. The crack velocity was found to be strongly dependent upon water vapor transport to the tip of the moving crack. The existence of a static fatigue limit was not conclusively established, however, it is speculated that slow crack growth behavior in Region 1 may be slower, by orders of magnitude, than that found in dense glasses. Previously announced in STAR as N82-11209
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  • 76
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    Simulated space radiation effects on dielectrics and coatings (1983)
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    Publikationsdatum: 2011-08-18
    Beschreibung: Simulation tests of space radiation have been performed for specific organic and inorganic materials. The test results for fifteen materials exposed to protons and five exposed to electrons are presented.
    Schlagwort(e): NONMETALLIC MATERIALS
    Materialart: IEEE Transactions on Nuclear Science (ISSN 0018-9499); NS-30; 4090-409
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  • 77
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    The effect of annealing on the creep of plasma-sprayed ceramics (1983)
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    Publikationsdatum: 2011-08-18
    Beschreibung: The creep of plasma sprayed ZrO2-8Y2O3 was measured at temperatures from 98 to 1250 C (180 to 220 F), and compared to creep of identical samples after annealing at temperatures from 98 to 1316 C (1800 to 2400 F). Loads and temperatures which produced significant creep of as sprayed ceramics produced no creep after annealing. Previously announced in STAR as N83-24799
    Schlagwort(e): NONMETALLIC MATERIALS
    Materialart: Ceramic Engineering and Science Proceedings (ISSN 0196-6219); 4; 819-827
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  • 78
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    Residual stress in plasma-sprayed ceramic turbine tip and gas-path seal specimens (1983)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: The residual stresses in a ceramic sheet material used for turbine blade tip gas path seals, were estimated. These stresses result from the plasma spraying process which leaves the surface of the sheet in tension. To determine the properties of plasma sprayed ZrO2-Y2O3 sheet material, its load deflection characteristics were measured. Estimates of the mechanical properties for sheet materials were found to differ from those reported for plasma sprayed bulk materials. Previously announced in STAR as N83-28380
    Schlagwort(e): NONMETALLIC MATERIALS
    Materialart: Ceramic Engineering and Science Proceedings (ISSN 0196-6219); 4; 802-809
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  • 79
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    Correlation of compressive and shear stress with spalling of plasma-sprayed ceramic materials (1983)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: Ceramics on metal substrates for potential use as high temperature seals or other applications are exposed to forces originating from differences in thermal expansion between the ceramic and the metal substrate. This report develops a relationship between the difference in expansion of the ceramic and the substrate, defines conditions under which shear between the ceramic and the substrate occurs, and those under which bending forces are produced in the ceramic. The off-axis effect of compression forces resulting from high temperature plastic flow of the ceramic producing buckling of the ceramic is developed. Shear is associated with the edge or boundary stresses on the component while bending is associated with the distortion of an interior region. Both modes are significant in predicting life of the ceramic. Previously announced in STAR as N83-27016
    Schlagwort(e): NONMETALLIC MATERIALS
    Materialart: Ceramic Engineering and Science Proceedings (ISSN 0196-6219); 4; 810-818
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  • 80
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    Life modeling of atmospheric and low pressure plasma-sprayed thermal-barrier coating (1984)
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    Publikationsdatum: 2011-08-19
    Beschreibung: The cycles-to-failure vs cycle duration data for three different thermal barrier coating systems, which consist of atmospheric pressure plasma-sprayed ZrO2-8 percent Y2O3 over similarly deposited or low pressure plasma sprayed Ni-base alloys, are presently analyzed by means of the Miller (1980) oxidation-based life model. Specimens were tested at 1100 C for heating cycle lengths of 1, 6, and 20 h, yielding results supporting the model's value.
    Schlagwort(e): NONMETALLIC MATERIALS
    Materialart: Ceramic Engineering and Science Proceedings (ISSN 0196-6219); 5; 470-478
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  • 81
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    Mechanical property measurements of plasma-sprayed thermal-barrier coatings subjected to oxidation (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: Techniques have been developed for measuring the tensile properties of plasma-sprayed coatings which are used in thermal barrier applications. The measurements have included the average Young's modulus, bond strength and elongation at failure. The oxidation behavior of the bond coat plays an important role in the integrity and adhesion of plasma-sprayed thermal barrier coatings. This work studies the nature of the high temperature degradation on the mechanical properties of the coating. Furnace tests have been carried out on U-700 alloy with bond coats of NiCrAlY or NiCrAlZr and an overlay of ZrO2-8 percent Y2O3. Weight gain measurements on the coatings have been examined with relation to the adhesion strength and failure observations. The results from an initial study are reported in this work.
    Schlagwort(e): NONMETALLIC MATERIALS
    Materialart: Ceramic Engineering and Science Proceedings (ISSN 0196-6219); 5; 479-490
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  • 82
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    Ethynyl-terminated polyarylates - Synthesis and characterization (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: Hydroxy-terminated polyarylates (HTPA) with number-average molecular weights of approximately 2500, 5000, 7500, and 10,000 were synthesized and converted to corresponding 4-ethynylbenzoyloxy-terminated polyarylates (ETPA) by reaction with 4-ethynylbenzoyl chloride. The terminal ethynyl groups were thermally reacted to provide chain extension and crosslinking. The cured ETPA exhibited higher glass transition temperatures (Tg) and better solvent resistance than a high molecular weight linear polyarylate. Solvent resistance was further improved by curing 2,2-bis(4-ethynylbenzoyloxy-4-prime-phenyl) propane, a coreactant, with ETPA at concentrations of approximately 10 percent (w/w).
    Schlagwort(e): NONMETALLIC MATERIALS
    Materialart: Journal of Polymer Science: Polymer Chemistry Edition (ISSN 0360-6376); 22; 3011-302
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  • 83
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    The development of aerospace polyimide adhesives (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: Few materials are available which can be used as aerospace adhesives at temperatures in the range of 300 C. The Materials Division at NASA-Langley Research Center developed several high temperature polyimide adhesives to fulfill the stringent needs of current aerospace programs. These adhesives are the result of a decade of basic research studies on the structure property relationships of both linear and addition aromatic polyimides. The development of both in house and commercially available polyimides is reviewed with regards to their potential for use as aerospace adhesives.
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  • 84
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    Polyimides - Tribological properties and their use as lubricants (1984)
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    Publikationsdatum: 2011-08-19
    Beschreibung: Friction, wear, and wear mechanisms of several different polyimide films, solid bodies, composites, and bonded solid lubricant films are compared and discussed. In addition, the effect of such parameters as temperatures, type of atmosphere, contact stress, and specimen configuration are investigated. A friction and wear transition occurs in some polyimides at elevated temperatures and this transition is related to molecular relaxations that occur in polyimides. Friction and wear data from an accelerated test (pin-on-disk) are compared to similar data from an end use test device (plain spherical bearing), and to other polymers investigated in a similar geometry.
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  • 85
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    Polyimide characterization studies - Effect of pendant alkyl groups (1984)
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    Publikationsdatum: 2011-08-19
    Beschreibung: The effect on selected polyimide properties when pendant alkyl groups were attached to the polymer backbone was investigated. A series of polymers were prepared using benzophenone tetracarboxylic acid dianhydride (BTDA) and seven different p-alkyl-m,p'-diaminobenzophenone monomers. The alkyl groups varied in length from C(1) (methyl) to C(9) (nonyl). The polyimide prepared from BTDA and m,p'-diaminobenzophenone was included as a control. All polymers were characterized by various chromatographic, spectroscopic, thermal, and mechanical techniques. Increasing the length of the pendant alkyl group resulted in a systematic decrease in glass transition temperature (Tg) for vacuum cured films. A 70 C decrease in Tg to 193 C was observed for the nonyl polymer compared to the Tg for the control. A corresponding systematic increase in Tg indicative of crosslinking, was observed for air cured films. Thermogravimetric analysis revealed a slight sacrifice in thermal stability with increasing alkyl length. No improvement in film toughness was observed.
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  • 86
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    Rheological characterization of addition polyimide matrix resins and prepregs (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: Although graphite-reinforced polyimide matrix composites offer outstanding specific strength and stiffness, together with high thermal oxidative stability, processing problems connected with their rheological behavior remain to be addressed. The present rheological studies on neat polyimide resin systems encountered outgassing during cure. A staging technique has been developed which can successfully handle polyimide samples, and novel methods were applied to generate rheological curves for graphite-reinforced prepregs. The commercial graphite/polyimide systems studied were PRM 15, LARC 160, and V378A.
    Schlagwort(e): NONMETALLIC MATERIALS
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  • 87
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    A thermoplastic polyimidesulfone (1984)
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    Publikationsdatum: 2011-08-19
    Beschreibung: A polymer system has been prepared which has the excellent thermoplastic properties generally associated with polysulfones, and the solvent resistance and thermal stability of aromatic polyimides. This material, with improved processability over the base polyimide, can be processed in the 260-325 C range in such a manner as to yield high quality, tough unfilled moldings; strong, high-temperature-resistant adhesive bonds; and well consolidated, graphite-fiber-reinforced moldings (composites). The unfilled moldings have physical properties that are similar to aromatic polysulfones which demonstrates the potential as an engineering thermoplastic. The adhesive bonds exhibit excellent retention of initial strength levels even after thermal aging for 5000 hours at 232 C. The graphite-fiber-reinforced moldings have mechanical properties which makes this polymer attractive for the fabrication of structural composites.
    Schlagwort(e): NONMETALLIC MATERIALS
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  • 88
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    Spherical microglass particle impingement studies of thermoplastic materials at normal incidence (1984)
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    Publikationsdatum: 2011-08-19
    Beschreibung: Light optical and scanning electron microscope studies were conducted to characterize the erosion resistance of polymethyl methacrylate (PMMA), polycarbonate (PC), polytetrafluoroethylene (PTFE) and ultra-high-molecular-weight-polyethylene (UHMWPE). Erosion was caused by a jet of spherical micro-glass beads at normal impact. During the initial stages of damage, the surfaces of these materials were studied using a profilometer. Material buildup above the original surface was observed on PC and PMMA. As erosion progressed, this buildup disappeared as the pit became deeper. Little or no buildup was observed on PTFE and on UHMWPE. UHMWPE and PTFE are the most resistant materials and PMMA the least. Favorable properties for high erosion resistance seem to be high values of ultimate elongation, and strain energy and a low value of the modulus of elasticity. Erosion-rate-versus-time curves of PC and PTFE exhibit incubation, acceleration and steady state periods. A continuously increasing erosion rate period was observed however for PMMA instead of a steady state period. At early stages of damage and at low impact pressure material removal mechanisms appear to be similar to those for metallic materials.
    Schlagwort(e): NONMETALLIC MATERIALS
    Materialart: ASLE Transactions; 27; 373-379
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  • 89
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    Metric-discontinuous zonal grid calculations using the Osher scheme (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: Computations on zonal grids - in particular, grids with metric discontinuities resulting from the interspersion of highly clustered regions with coarse regions - are possible using a fully conservative form of the Osher upwind scheme. These zonal grids can result from an abrupt clustering of points near solution discontinuities or near other flow features that require improved resolution. The zonal approach is shown to capture shocks with almost 'shock-fitting' quality but with minimal effort. Results for inviscid flow, including quasi-one-dimensional nozzle flow, supersonic flow over a cylinder, and blast-wave diffraction by a ramp, are presented. These calculations demonstrate the powerful capabilities of the Osher scheme used in conjunction with zonal grids in simulating flow fields with complex shock patterns.
    Schlagwort(e): AERODYNAMICS
    Materialart: Computers and Fluids (ISSN 0045-7930); 12; 3, 19
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  • 90
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    Thermogravimetric analysis of silicon carbide-silicon nitride polycarbosilazane precursor during pyrolysis from ambient to 1000 C (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: Thermogravimetric analysis data are presented on the unmeltable polycarbosilazane precursor of silicon carbide-silicon nitride fibers, over the room temperature-1000 C range in a nitrogen atmosphere, in order to establish the weight loss at various temperatures during the precursor's pyrolysis to the fiber material. The fibers obtained by this method are excellent candidates for use in applications where the oxidation of carbon fibers (above 400 C) renders them unsuitable.
    Schlagwort(e): NONMETALLIC MATERIALS
    Materialart: Journal of Materials Science Letters (ISSN 0261-8028); 3; 802-804
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  • 91
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    An exploratory study of area-efficient vortex flap concepts (1983)
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    Publikationsdatum: 2011-08-18
    Beschreibung: The potential of planform modification and hinge-line relocation to improve the thrust efficiency of vortex flaps was experimentally investigated on a 60-deg cropped delta wing model. Spanwise segmentation of the flap, together with chord-tailoring of the segments, allowed the vortex to be maintained on the outboard flap surfaces to higher angles of attack. In addition, location of the flap hinge aft of and underneath the wing leading edge generated substantial thrust from the vortex suction acting on the leading-edge lower surface. A combination of these beneficial effects allowed the flap/wing area to be reduced from 11.4 percent of the continuous flap to 6.3 percent of segmented flap, essentially without detriment to the incremental lift-to-drag ratio due to flap addition in the lift coefficient range 0.5-0.7 based on the basic wing area.
    Schlagwort(e): AERODYNAMICS
    Materialart: Journal of Aircraft (ISSN 0021-8669); 20; 1062-106
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  • 92
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    Observations and implications of natural laminar flow on practical airplane surfaces (1983)
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    Publikationsdatum: 2011-08-18
    Beschreibung: Previously cited in issue 20, p. 3138, Accession no. A82-40893
    Schlagwort(e): AERODYNAMICS
    Materialart: Journal of Aircraft (ISSN 0021-8669); 20; 993-1006
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  • 93
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    Ultrasonic mixing of epoxy curing agents (1983)
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    Publikationsdatum: 2011-08-18
    Beschreibung: A new technique for mixing solid curing agents into liquid epoxy resins using ultrasonic energy was developed. This procedure allows standard curing agents such as 4,4 prime-diaminodiphenyl sulfone (4,4 prime-DDS) and its 3,3 prime-isomer, (3,3 prime-DDS) to be mixed without prior melting of the curing agent. It also allows curing agents with very high melt temperatures such as 4,4 prime-diaminodiphenyl sulfone (4,4 prime-DDS) and its 3,3 prime-isomer, (3,3 prime-DDS) to be mixed without prior melting of the curing agent. It also allows curing agents with very high melt temperatures such as 4,4 prime-diaminobenzophenone (4,4 prime-DABP) (242 C) to be mixed without premature curing. Four aromatic diamines were ultrasonically blended into MY-720 epoxy resin. These were 4, 4 prime-DDS; 3,3 prime-DDA; 4, 4 prime-DABP and 3,3 prime-DABP. Unfilled moldings were cast and cured for each system and their physical and mechanical properties compared. Previously announced in STAR as N83-27018
    Schlagwort(e): NONMETALLIC MATERIALS
    Materialart: SAMPE Quarterly (ISSN 0036-0821); 14; 46-50
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  • 94
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    Hardness of dense beta-Si3N4 (1983)
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    Publikationsdatum: 2011-08-18
    Beschreibung: The effects of small changes in the concentration of an oxygen content densification aid on the room temperature microhardness of hot isostatically pressed and sintered beta-Si3N4 ceramics are studied. The compositions studied were Si3N4 containing 7 wt. pct BeSiN2, a fixed nonoxide densification aid, and 1.9-3.7 wt. pct oxygen as a second, variable densification aid. A proportional relationship between high density and high oxygen content, regardless of heat treatment type, is noted.
    Schlagwort(e): NONMETALLIC MATERIALS
    Materialart: Journal of Materials Science Letters (ISSN 0261-8028); 2; 657-659
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  • 95
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    Stability of shock waves attached to wedges and cones (1983)
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    Publikationsdatum: 2011-08-18
    Beschreibung: Previously cited in issue 06, p. 799, Accession no. A82-17876
    Schlagwort(e): AERODYNAMICS
    Materialart: AIAA Journal (ISSN 0001-1452); 21; 1611-161
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  • 96
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    Stability of silica heat shield materials in the Space Shuttle environment (1983)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: Sample tiles of Space Shuttle reusable surface insulation (RSI) and fibrous refractory composite insulation (FRCI) have been alternately exposed to simulated mission heating and the Kennedy Space Center launch-pad environment for up to 50 cycles. The two types of tiles were coated with an identical glass composition. The coating on RSI tiles was prone to cracking in the test environment while the same coating on FRCI was not. Absorption of water contaminated with environmental deposits resulted in accelerated devitrification in the RSI tiles. Devitrification in FRCI tiles was significantly less. The rate of environmental degradation of tiles appeared to be dependent on the amount of water absorption.
    Schlagwort(e): NONMETALLIC MATERIALS
    Materialart: Ceramic Engineering and Science Proceedings (ISSN 0196-6219); 4; 564-577
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  • 97
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    Surface chemistry, friction, and wear of Ni-Zn and Mn-Zn ferrites in contact with metals (1983)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: X-ray photoelectron and Auger electron spectroscopy analysis were used in sliding friction experiments. These experiments were conducted with hot-pressed polycrystalline Ni-Zn and Mn-Zn ferrites, and single-crystal Mn-Zn ferrite in contact with various transition metals at room temperature in both vacuum and argon. The results indicate that Ni2O3 and Fe3O4 were present on the Ni-Zn ferrite surface in addition to the nominal bulk constituents, while MnO2 and Fe3O4 were present on the Mn-Zn ferrite surface in addition to the nominal bulk constituents. The coefficients of friction for the ferrites in contact with metals were related to the relative chemical activity of these metals. The more active the metal, the higher is the coefficient of friction. The coefficients of friction for the ferrites were correlated with the free energy of formation of the lowest metal oxide. The interfacial bond can be regarded as a chemical bond between the metal atoms and the oxygen anions in the ferrite surfaces. The adsorption of oxygen on clean metal and ferrite does strengthen the metal-ferrite contact and increase the friction. The ferrites exhibit local cracking and fracture with sliding under adhesive conditions. All the metals transferred to the surfaces of the ferrites in sliding. Previously announced in STAR as N83-19901
    Schlagwort(e): NONMETALLIC MATERIALS
    Materialart: Ceramic Engineering and Science Proceedings (ISSN 0196-6219); 4; 674-693
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  • 98
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    Shrinkage of amorphous silica fibers (1983)
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    Publikationsdatum: 2011-08-18
    Beschreibung: By the application of a new technique, the viscosity of amorphous silica fibers was determined in the 1100-1350 C temperature range. An equation was derived that describes the kinetics of shrinkage of the fibers in terms of their radius, viscosity, and surface tension.
    Schlagwort(e): NONMETALLIC MATERIALS
    Materialart: Ceramic Engineering and Science Proceedings (ISSN 0196-6219); 4; 492-501
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  • 99
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    Phase distributions in plasma-sprayed zirconia-yttria (1983)
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    Publikationsdatum: 2011-08-18
    Beschreibung: The distribution of phases in plasma-sprayed zirconia-yttria has been determined over a range of yttria levels from 0 to 26.1 molpct YO(1.5) using room temperature X-ray diffractometry. Pure, plasma-sprayed zirconia is composed almost entirely of the monoclinic phase. At levels of yttria between 4 and 10 percent, a quenched-in tetragonal phase predominates, and at higher levels the cubic phase predominates. The phase distributions are compared with previously reported test lives of thermal barrier coatings formed from these materials. Regions of optimal lives were found to correlate with regions having high amounts of the tetragonal phase, small but nonzero amounts of the monoclinic phase, and little or none of the cubic phase. Possible relationships between phase composition and coating performance are discussed.
    Schlagwort(e): NONMETALLIC MATERIALS
    Materialart: American Ceramic Society Bulletin (ISSN 0002-7812); 62; 1355-135
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  • 100
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    Development of plane strain fracture toughness test for ceramics using Chevron notched specimens (1983)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: Chevron-notched four-point-bend and short-bar specimens have been used to determine the fracture toughness of sintered aluminum oxide and hot-pressed silicon nitride ceramics. The fracture toughness for Si3N4 is found to be essentially independent of the specimen size and chevron notch configuration, with values ranging from 4.6 to 4.9 MNm exp -3/2. In contrast, significant specimen size and notch geometry effects have been observed for Al2O3, with the fracture toughness ranging from 3.1 to 4.7 MNm exp -3/2. These effects are attributed to a rising crack growth resistance curve for the Al2O3 tested.
    Schlagwort(e): NONMETALLIC MATERIALS
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