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  • Other Sources  (594)
  • AERODYNAMICS  (419)
  • SPACECRAFT DESIGN, TESTING AND PERFORMANCE  (175)
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  • 1980-1984  (594)
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  • 1982  (594)
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  • 1980-1984  (594)
  • 1945-1949
  • 1925-1929
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  • 1
    Publication Date: 2006-02-14
    Description: 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.
    Keywords: AERODYNAMICS
    Type: KC-135 Winglet Program Rev.; p 103-116
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  • 2
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    In:  CASI
    Publication Date: 2006-02-14
    Description: 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.
    Keywords: AERODYNAMICS
    Type: KC-135 Winglet Program Rev.; p 1-46
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  • 3
    Publication Date: 2006-02-14
    Description: 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.
    Keywords: AERODYNAMICS
    Type: KC-135 Winglet Program Rev.; p 47-102
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  • 4
    Publication Date: 2006-02-14
    Description: A comprehensive set of measurements about the orbiter environment are provided by the plasma diagnostics package (PDP). Ion and electron particle densities, energies, and spatial distribution functions; ion mass for identification of particular molecular ion species; and magnetic fields, electric fields and electromagnetic waves over a broad frequency range are studied. Shuttle environmental measurements will be made both on the pallet and, by use of the remote manipulator system (RMS), the PDP will be maneuvered in and external to the bay area to continue environmental measurements and to carry on a joint plasma experiment with the Utah State University fast-pulsed electron generator. Results of orbiter environment EMI measurements and S-band field strengths as well as preliminary results from wake search operations indicating wake boundary identifiers are reported.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA. Goddard Space Flight Center 12th Space Simulation Conf.; 8 p
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  • 5
    Publication Date: 2006-02-14
    Description: The Earth radiation budget experiment (ERBE) software development approach is described. An iterative development approach was adopted which provides for three releases or versions of the processing system, each of increasing levels of complexity and solidity. The final release of the system will be used to process the flight data. The major phases for each iterative release consist of specifications developed in concert with the science team, preliminary design, subsystem reviews, coding, subsystem code walkthroughs, system testing, system documentation, and project status review.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA. Goddard Space Flight Center 12th Space Simulation Conf.; 15 p
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  • 6
    Publication Date: 2006-02-14
    Description: The correlation of outgassing to the stability of the damping properties of polymer materials to be used in spacecraft structures is discussed. A test series was devised to obtain basic information from off-the-shelf damping materials. The test results could be considered as a guideline toward the application of these materials. Eight materials were selected to form a representative cross section of those polymers having both ready availability as commercial damping materials and desirable properties. A table indicates the temperatures at which peak damping occurs at 1 Hz and the type of beam specimen used in the vacuum exposure tests. These materials as a group cover the temperature range of -85 C to 38 C.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA. Goddard Space Flight Center 12th Space Simulation Conf.; 25 p
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  • 7
    Publication Date: 2006-02-14
    Description: A molecular beam facility to simulate the space environment of a spacecraft at low orbit was designed with the intent of studying the effect on the properties of optical elements of oxygen atoms impacting at orbital velocity. The four-stage differentially pumped molecular beam facility includes a variety of oxygen atom beam sources which cover a wide range of velocities (1 km/sec to approximately 8 km/sec), in addition to the ultra-clean experimental environmental of an ultra-high vacuum chamber and an optical diagnostic set-up. The primary oxygen atom beam source used to obtain the 8 km/sec O atoms is an arc heated source. It consists of a modified commercially available plasma torch. The modifications include attachments which provide for a nozzle which is used to expand the atomic beam into the vacuum system, and exhaust channels to dispose of excess torch gas. The torch operates in the 'nontransferred' mode of operation, that is the electric arc is confined within the torch. A plasma is formed in helium by a dc arc. A small amount of O2 is injected downstream from the arc where it is thermally dissociated by the hot He into oxygen atoms. The high temperature and isentropic expansion give the oxygen atoms their velocity. Using seeded beam techniques, oxygen atom beams of approximately 3.5 and approximately 1.5 km/sec, respectively, are obtained.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA. Goddard Space Flight Center 12th Space Simulation Conf.; 1 p
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  • 8
    Publication Date: 2006-02-14
    Description: A preliminary assessment of the space shuttle contamination environment was made using data from the first two orbital flight tests, STS-1 and STS-2. Data sources consisted of crew observations during flight, postflight vehicle inspection, and the induced environment contamination monitor which was used on STS-2 and consists of 10 instruments. These instruments are used to measure gas phase contaminants, particle population, humidity, and molecular deposition in the orbiter payload bay during ascent and descent and particle population, molecular deposition, and gas cloud during orbital flight. Results of the measurements described are presented in summary form and indicate low molecular deposition rates for both pressurized and orbital flight.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA. Goddard Space Flight Center 12th Space Simulation Conf.; 21 p
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  • 9
    Publication Date: 2006-02-14
    Description: The structure of the European Space Agency (ESA) is described. The major test facilities used for ESA programs are described. Facility characteristics and special test methods are described.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA. Goddard Space Flight Center 12th Space Simulation Conf.; 28 p
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  • 10
    Publication Date: 2006-02-14
    Description: The training program and procedures developed and implemented at the space simulation laboratory at Martin Marietta Aerospace in Denver are discussed. The training of technicians and professionals as well as preparation for instructors is covered. Training manuals and their compilation are reported as applicable to the specific needs of the laboratory. The development of a space simulation course as part of the Martin Marietta Continuing Education Night School approaching space simulation from an academic viewpoint is presented. Finally, public relations tours of the facility as an informational/educational tool are discussed.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA. Goddard Space Flight Center 12th Space Simulation Conf.; 5 p
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  • 11
    Publication Date: 2006-02-14
    Description: A test involving a flow of hot hydrazine decomposition products at a rate of 13.6 g/s (0.03 lb/s) established the requirement to maintain pressure in an 11.9-m-(39 ft) diameter space chamber below 200 microns. The flow, 2/3 hydrogen and 1/3 nitrogen by volume, continued for several periods ranging from 3 to 15 min. The pressure requirement was necessary to minimize thermal effects of the gas on the test vehicle but was well beyond the capability of the existing facility pumps. Various methods of obtaining additional temporary jump capacity were considered. From these, the slugged-charcoal approach was selected as the quickest and least expensive method to implement.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA. Goddard Space Flight Center 12th Space Simulation Conf.; 23 p
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  • 12
    Publication Date: 2006-02-14
    Description: A thermal balance test (controlled flux intensity) on a simple black dummy spacecraft using IR lamps was performed and evaluated, the latter being aimed specifically at thermal mathematical model (TMM) verification. For reference purposes the model was also subjected to a solar simulation test (SST). The results show that the temperature distributions measured during IR testing for two different model attitudes under steady state conditions are reproducible with a TMM. The TMM test data correlation is not as accurate for IRT as for SST. Using the standard deviation of the temperature difference distribution (analysis minus test) the SST data correlation is better by a factor of 1.8 to 2.5. The lower figure applies to the measured and the higher to the computer-generated IR flux intensity distribution. Techniques of lamp power control are presented. A continuing work program is described which is aimed at quantifying the differences between solar simulation and infrared techniques for a model representing the thermal radiating surfaces of a large communications spacecraft.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA. Goddard Space Flight Center 12th Space Simulation Conf.; 26 p
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  • 13
    Publication Date: 2006-02-14
    Description: The Jet Propulsion Laboratory 25-foot space simulator with its 5.8-m (19-ft) diameter simulated solar beam provides an excellent facility for measuring the optical characteristics of parabolic solar concentrator panels and gores. The virtual source position and size were determined by using a single lamp of the 37 xenon 30-kW source array with only the center lens in the 19-channel optical mixer. This data was used to define the optical test geometry, and it allowed accurate measurement of focal length and surface deviations of the mirror under test. A flux distribution of a typical solar concentrator placed directly on the solar beam gives measurements of performance at the focal point of the parabolic surface.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA. Goddard Space Flight Center 12th Space Simulation Conf.; 19 p
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  • 14
    Publication Date: 2006-02-14
    Description: Several mathematical models, including a minimum integral square criterion problem, were used for the qualitative investigation of fuel optimal maneuvers for spacecraft with fixed thrusters. The solutions consist of intervals of "full thrust" and "coast" indicating that thrusters do not need to be designed as "throttleable" for fuel optimal performance. For the primary model considered, singular solutions occur only if the optimal solution is "pure translation". "Time optimal" singular solutions can be found which consist of intervals of "coast" and "full thrust". The shape of the optimal fuel consumption curve as a function of flight time was found to depend on whether or not the initial state is in the region admitting singular solutions. Comparisons of fuel optimal maneuvers in deep space with those relative to a point in circular orbit indicate that qualitative differences in the solutions can occur. Computation of fuel consumption for certain "pure translation" cases indicates that considerable savings in fuel can result from the fuel optimal maneuvers.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: Alabama Univ. in Huntsville The 1981 NASA(ASEE Summer Fac. Fellowship Program; 21 p
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  • 15
    Publication Date: 2006-02-14
    Description: A planar model of a space base and one module is considered. For this simplified system, a feedback controller which is compatible with the modular construction method is described. The systems dynamics are decomposed into two parts corresponding to base and module. The information structure of the problem is non-classical in that not all system information is supplied to each controller. The base controller is designed to accommodate structural changes that occur as the module is added and the module controller is designed to regulate its own states and follow commands from the base. Overall stability of the system is checked by Liapunov analysis and controller effectiveness is verified by computer simulation.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: Alabama Univ. in Huntsville The 1981 NASA(ASEE Summer Fac. Fellowship Program; 35 p
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  • 16
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    In:  CASI
    Publication Date: 2006-02-14
    Description: A residual gas analyzer (RGA), a device for measuring the amounts and species of various gases present in a vacuum system is discussed. In a recent update of the RGA, it was shown that the use of microprocessors could revolutionize data acquisition and data reduction. This revolution is exemplified by the Inficon 1Q200 RGA which was selected to meet the needs of this update. The Inficon RGA and the Zilog microcomputer were interfaced in order the receive and format the digital data from the RGA. This automated approach is discussed in detail.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA. Goddard Space Flight Center 12th Space Simulation Conf.; 16 p
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  • 17
    Publication Date: 2006-02-14
    Description: By using infrared images obtained from GOES satellite, the digital count values of pixels representing blackbody temperatures of the cloud top, convective storms are observed throughout their life cycles. Clouds associated with a tornadic storm are compared with those without a tornadic storm to illustrate how the infrared and visible observations from a geosynchronous satellite can be used to study the differences in their life cycles.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA. Goddard Space Flight Center 12th Space Simulation Conf.; 11 p
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  • 18
    Publication Date: 2006-02-14
    Description: An environmental noise assessement of the initial launch of the Space Transportation System, STS-1 Columbia was conducted. The principal objective of the environmental noise assessment was to measure the noise generated during the initial launch of the space shuttle to ascertain the validity of the levels predicted in the 1979 environmental impact statement. In the 1979 study information obtained for expendable launch vehicles, Titan, Saturn and Atlas was used to predict the noise levels that would be generated by the simultaneous firing of the two solid rocket boosters and the three space shuttle main engines. Fifteen monitoring sites were established in accessable areas located from 4,953 to 23,640 meters from the launch pad. Precision sound level meters were used to capture the peak level during the launch. Data obtained was compared to the predicted levels and were also compared to the identified levels, standards and criteria established by the federal agencies with noise abatement and control responsibilities.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA. Goddard Space Flight Center 12th Space Simulation Conf.; 16 p
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  • 19
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    Publication Date: 2006-02-14
    Description: Multilayer insulation blankets used for the attenuation of radiant heat transfer in spacecraft are addressed. Typically, blanket effectiveness is degraded by heat leaks in the joints between adjacent blankets and by heat leaks caused by the blanket fastener system. An approach to blanket design based upon modular sub-blankets with distributed seams and upon an associated fastener system that practically eliminates the through-the-blanket conductive path is described. Test results are discussed providing confirmation of the approach. The specific case of the thermal control system for the optical assembly of the Space Telescope is examined.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA. Goddard Space Flight Center 12th Space Simulation Conf.; 8 p
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  • 20
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    Publication Date: 2006-04-12
    Description: Research efforts are reviewed on the space durability of materials, including radiation effects on polymer matrix composites and films, dimensional stability of polymer matrix composites and tension-stabilized cables, and thermal control coatings. Research to date has concentrated on establishing a fundamental understanding of space environmental effects on current graphite-reinforced composites and polymer systems, and development of analytical models to explain observed changes in mechanical, physical, and optical properties. As a result of these research efforts, new experimental facilities have been developed to simulate the space environment and measure the observed property changes. Chemical and microstructural analyses have also been performed to establish damage mechanisms and the limits for accelerated testing. The implications of these results on material selection and system performance are discussed and additional research needs and opportunities in the area of tougher resin/matrix and metal/matrix composites are identified.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: Advan. Mater. Technol.; p 357-380
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  • 21
    Publication Date: 2011-08-18
    Description: Single-stage and two-stage launch vehicles were evaluated for various levels of propulsion technology and payloads. The evaluation included tradeoffs between ascent flight performance and vehicle sizing that were driven by engine mass, specific impulse, and propellant requirements. Numerous mission, flight, and vehicle-related requirements and constraints were satisfied in the design process. The results showed that advanced technology had a large effect on reducing both single- and two-stage vehicle size. High-pressure hydrocarbon-fueled engines that were burned in parallel with two-position nozzle hydrogen-fueled engines reduced dry mass by 23% for the two-stage vehicle and 28% for the single-stage vehicle as compared to an all-hydrogen-fueled system. The dual-expander engine reduced single-stage vehicle dry mass by 41%. Using advanced technology, the single-stage vehicle became comparable in size and sensitivity to that of the two-stage vehicle for small payloads.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: Journal of Spacecraft and Rockets; 19; July-Aug
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  • 22
    Publication Date: 2011-08-18
    Description: Attention is directed to the acoustics research of the 1950s and 1960s for guidance in understanding and quantizing the turbulence amplification that can occur in regions of shock-wave boundary-layer interaction. Three primary turbulence amplifier-generator mechanisms are identified and shown, by linear analysis, to be responsible for turbulence amplification across a shock wave in excess of 100% of the incident turbulence intensity.
    Keywords: AERODYNAMICS
    Type: AIAA Journal; 20; July 198
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  • 23
    Publication Date: 2011-08-18
    Description: A comparison is made between the storable-propellant engine and an equivalent dual-expander engine using oxygen, propane, and hydrogen propellants. The propane and hydrogen dual-expander engine is then compared with previous results with separate propane and hydrocarbon engines. It is shown that the dual-expander reduces vehicle dry mass from 94 to 89 Mg, or 5%. The hydrogen-only thrust of the dual-expander is 0.4 MN, while the separate hydrogen engines have a thrust of 2.3 MN. The low thrust level increases the difficulty of cooling the dual-expander engine, and additional hydrogen flow is added for transpirational cooling. This additional hydrogen flow leads to an increase in the hydrogen tank size. It is also shown that storable propellants increase the dry mass of single-stage earth-to-orbit vehicles by about 20% and the gross mass by about 54%. It is concluded that dual-expander engines should be studied with several thrust splits and thrust levels.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: Journal of Spacecraft and Rockets; 19; May-June
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  • 24
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    Publication Date: 2011-08-18
    Description: Illustrations for a presentation on superplastic forming/diffusion bonding titanium design concepts are presented. Sandwich skin panels with hat section, semicircular corrugation, sine wave, and truss cores are shown. The fabrication of wing panels is illustrated, and applications to the design of advanced variable sweep bombers summarized.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center Laminar Flow Control; p 95-110
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  • 25
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    Publication Date: 2011-08-18
    Description: Illustrations for a presentation demonstrating superplastic forming/diffusion bonding titanium porous panels are presented. Fabrication phases, sandwich panels, load bearing qualities, microstructure, and panel surface after finishing are illustrated.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center Laminar Flow Control; p 111-138
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  • 26
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    Publication Date: 2011-08-18
    Description: The X-29A is a technology demonstrator. The FSW is just one of the technologies. Others include the following: discrete variable camber, relaxed static stability, triplex digital fly-by-wire (FBW) control system, variable-incidence/close-coupled canard, aeroelastically tailored composite wing, and thin supercritical airfoil. The growth potential for additional technologies is shown.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center Wind-Tunnel(Flight Correlation, 1981; p 177-189
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  • 27
    Publication Date: 2011-08-18
    Description: The use of correlated data in airplane development is discussed. Areas of interest include initial airworthiness of an aircraft, low-speed configuration optimization, and high-speed configuration optimization. Data from wind tunnel tests are shown to be significant when applied to guarantee compliance, which includes fuel consumption, airspeeds, and takeoff and landing performance. The use of correlation in achieving FAA certification is also discussed.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center Wind-Tunnel-Flight Correlation, 1981; p 141-157
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  • 28
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    Publication Date: 2011-08-18
    Description: F-15 correlation data for longitudinal control and inlet-ramp effectiveness, and horizontal-tail setting for trim are presented. The Reynolds number effect on airfoil laminar bubble burst is included.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center Wind-Tunnel(Flight Correlation, 1981; p 109-115
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  • 29
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    Publication Date: 2011-08-18
    Description: The XB-70-1 was selected for a wind-tunnel/flight correlation program as representative of a large, flexible supersonic airplane similar to a supersonic transport. Tests were made to determine the effects of control deflections, wing tip deflection, and variations in inlet mass flow (additive drag).
    Keywords: AERODYNAMICS
    Type: Wind-Tunnel(Flight Correlation, 1981; p 65-91
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  • 30
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    Publication Date: 2011-08-18
    Description: Considerations and recommendations for correlation are given. Basic tunnel calibration prior to research and development tests is suggested. Areas of concentration include: wing cruise drag and drag rise, wing separation and stall, afterbody and base drag, propulsion effects, vortex flows, cavity flows, and excrescences.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center Wind-Tunnel(Flight Correlation, 1981; p 191-197
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  • 31
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    Publication Date: 2011-08-18
    Description: A 2-percent-scale model was designed for testing in the NTF. This model has remotely controlled elevons, body flap, and rudder to minimize tunnel entries associated with configuration changes in the NTF. The Shuttle Orbiter has a very large aerodynamic data base obtained in ground facilities. Since the vehicle flight-test program has already begun, a large amount of flight data can be analyzed and correlated with the NTF results.
    Keywords: AERODYNAMICS
    Type: Wind-Tunnel(Flight Correlation, 1981; p 173-176
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  • 32
    Publication Date: 2011-08-18
    Description: It is found from the comparisons that large longitudinal aerodynamic differences exist between wind tunnel predictions and flight measurements. Cold gas plume simulation underpredicted Shuttle base pressure. It is concluded that observed flight prediction increments are probably caused by several factors such as input error, independent variable errors, plume effects, and Reynolds number effects.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center Wind-Tunnel(Flight Correlation, 1981; p 133-140
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  • 33
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    Publication Date: 2011-08-18
    Description: Correlation efforts and selected results for transonic drag are reviewed. A process to reduce the typical error sources to decrease the errors inherent in the transonic aircraft development process is summarized.
    Keywords: AERODYNAMICS
    Type: Wind-Tunnel(Flight Correlation, 1981; p 93-108
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  • 34
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    Publication Date: 2011-08-18
    Description: Predicted and flight-test drag on the C-5A and the C-141 are correlated. Equivalent rigid flight-test profile drag and a rigid estimate based on wind tunnel data are also correlated. Correlations for the National Transonic Facility are included.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center Wind-Tunnel(Flight Correlation, 1981; p 33-46
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  • 35
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    Publication Date: 2011-08-18
    Description: Wind tunnel/flight correlation history from the P-51 to the F-8 supercritical wing is reviewed, showing that researchers continue to be faced with nearly identical discrepancies in predicted versus measured drag. The capabilities of the National Transonic Facility to allow assessment of the effects which have heretofore plagued researchers and aircraft designers are anticipated.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center Wind-Tunnel(Flight Correlation, 1981; p 23-32
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  • 36
    Publication Date: 2011-08-18
    Description: The explicit-implicit predictor corrector method of MacCormack (1981) is applied to the analysis of flows past airfoils. By comparing results obtained with different methods and meshes, it is shown that the above method provides, after certain modifications, reasonably good predictions of inviscid and viscous flows about an airfoil. Good results are also obtained for the transonic regime if the free-stream conditions are correct and if a suitable mesh is used.
    Keywords: AERODYNAMICS
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  • 37
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    Publication Date: 2011-08-18
    Description: An improved method, based on one strip approximation of the method of integral relations which was reported originally by Belov, Ginzburg and Shub (1973), is presented for the calculation of flow parameters in the impingement region of a supersonic, underexpanded jet striking a normal surface located within the first cell. The results are presented for two impingement conditions and found to be in good agreement with the experimental data.
    Keywords: AERODYNAMICS
    Type: Aeronautical Quarterly; 33; Aug. 198
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  • 38
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    Publication Date: 2011-08-18
    Description: The Applications Technology Satellite-6 (ATS-6) geosynchronous satellite charged up to -2200 V in sunlight on day 178, 1974. This event, being the highest known spacecraft charging event in sunlight, is used to estimate a worst case geosynchronous plasma environment for predicting the spacecraft potential in eclipse. The advantage of using this sunlight spectrum as opposed to an eclipse case is that the ion and electron fluxes to the detectors are shifted only slightly due to the spacecraft potential. After correcting the available data for satellite potential and missing data above 81 KeV, it is found that the plasma can be characterized by a single Maxwellian approximation having an electron density of 1.22/cu cm, electron temperature of 16 KeV, hydrogen ion density of 0.24/cu cm, and hydrogen ion temperature of 29 KeV. In eclipse the spacecraft would have charged up to -28 kV, the highest estimated potential to date in the earth's plasma environment.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: Journal of Spacecraft and Rockets; 19; Sept
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  • 39
    Publication Date: 2011-08-18
    Description: Initial results of a NASA study of the lift-drag characteristics of a 12.84/7 deg biconic model intended for airbraking during atmospheric entry of probes to Mars, Venus, Saturn, and Titan are reported. Pressure distributions and shock shapes were measured in the Langley 20 in. Mach 6 tunnel with the spherically blunted bent-nose model set at angles from 0-25 deg. Pressure distributions and shock shapes where computed using the STEIN flowfield code, which features a MacCormack scheme to integrate the three-dimensional Euler equations, the Rankine-Hugoniot jump conditions to model shock waves as discontinuities, and requires a supersonic condition at every step. A comparison was made between measured and predicted values. The leeward shock angle was found to be predictable to within 3% for all angles of attack, while parabolized Navier-Stokes equations are regarded as offering more accurate results than the STEIN code for surface pressure distributions.
    Keywords: AERODYNAMICS
    Type: AIAA Journal; 20; Aug. 198
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  • 40
    Publication Date: 2011-08-18
    Description: The Lomax and Sluder method for adapting slender-wing theory to delta or rectangular wings by making chordwise and compressibility corrections is extended to cover wings of any arbitrary planform in subsonic and supersonic flows. The numerical accuracy of the present work is better than that of the Lomax-Sluder results. Comparison of the results of this work with those of the vortex-lattice method and Kernel function method for a family of Gothic and arrowhead wings shows good agreement. A universal curve is proposed for the evaluation of the lift coefficient of a low aspect ratio wing of an arbitrary planform in subsonic flow. The location of the center of pressure can also be estimated.
    Keywords: AERODYNAMICS
    Type: AIAA Journal; 20; Aug. 198
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  • 41
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    Publication Date: 2011-08-18
    Description: (Previously announced in STAR as N81-30385)
    Keywords: AERODYNAMICS
    Type: Journal of Fluid Mechanics; 118; May 1982
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  • 42
    Publication Date: 2011-08-18
    Description: A procedure for the evaluation of wall interference corrections for three-dimensional aircraft configurations is presented. The Mach number and angle-of-attack corrections are obtained by numerically solving the Laplace equation in a parallelepiped with boundary conditions supplied mainly from experimental pressure measurements. A portion of these measurements and other wind-tunnel data required by the procedure may be replaced by theoretical estimates if not available from experiments. The accuracy of the correction results will then depend on the accuracy of these estimates. The correction procedure is applied to an isolated wing and to a wing-tail configuration in a solid-wall wind tunnel. It is found that neglecting twist and camber corrections for the wing effectively increases the tail angle-of-attack correction. Two different Mach number corrections can be calculated for the wing and tail. However, since only one Mach number correction is allowed for both the wing and the tail, and since the wing surface area is larger than the tail surface area, the final correction tends to be closer to the required wing correction. This is a source of error for the tail results.
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft; 19; June 198
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  • 43
    Publication Date: 2011-08-18
    Description: (Previously announced in STAR as N81-29092)
    Keywords: AERODYNAMICS
    Type: AIAA Journal; 20; May 1982
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  • 44
    Publication Date: 2011-08-18
    Description: Helicopter drop tests were made of models of the Pioneer Venus probe descent configurations to characterize their unsteady forces and angular dynamics in equilibrium descent. The axial and normal forces were found to be unsteady in magnitude by about 10 and 5% of the mean axial force, respectively. A cycle of the axial variation takes place in flight distances of from 15 to 40 diameters. The unsteadiness almost certainly is associated with the wake. Angular motions which do not converge to zero angle of attack even in very long duration descent are excited by the unsteady pitching moments. The nearly spherical large probe model was aerodynamically more unsteady than the round-nosed conical small probe model. Data returned from Venus by the Pioneer Venus probes show unsteady axial forces and angular motions similar to those seen in the drop tests.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: Journal of Spacecraft and Rockets; 19; Sept
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  • 45
    Publication Date: 2011-08-18
    Description: Cross-correlation techniques are used to measure the sound radiated by wing/flap airfoil configurations in the NASA-Ames 40 x 80 ft wind tunnel using a 6.7-m semispan model with three deployed flaps. The dominant source of flap noise is identified as the flap side edges, which exceeds that radiated by the midspan region by more than 10 dB. The turbulent surface eddies at the flap side edge have scales on the order of one-half the flap chord. The installation of flap actuator fairings at the flap side edge reduces the noise radiated from that location by 10 to 15 dB. The cross-correlation technique extracts airframe noise radiated by specific surface locations from the tunnel background noise, even when the noise is 25 dB higher than the measured airframe noise level.
    Keywords: AERODYNAMICS
    Type: Acoustical Society of America; vol. 71
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  • 46
    Publication Date: 2011-08-18
    Description: Computed solutions of the time-dependent, Reynolds-averaged Navier-Stokes equations for three-dimensional flows having thin shear layers are analyzed, using topological concepts. Specific examples include the transonic flow over a body of revolution with conical afterbody at moderate angles of incidence to the free stream. Experimental flow-visualization techniques are simulated graphically to visualize the computed flow. Scalar and vector fluid dynamic properties, such as pressure, shear stress, and vorticity on the body surface, are presented as topological maps, and their relationship to one another in terms of orientation and singular points is discussed. The extrapolation from these surface topologies toward the understanding of external flow-field behavior is discussed and demonstrated.
    Keywords: AERODYNAMICS
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  • 47
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    Publication Date: 2014-09-11
    Description: The evaluation techniques, results and conclusions for the flight flutter testing conducted on a KC-135A airplane configured with and without winglets are discussed. Test results are presented for the critical symmetric and antisymmetric modes for a fuel distribution that consisted of 10,000 pounds in each wing main tank and empty reserve tanks. The results indicated that a lightly damped oscillation was experienced for a winglet configuration of a 0 deg cant and -4 deg incidence. The effects of cant and incidence angle variation on the critical modes are also discussed. Lightly damped oscillations were not encountered for any other winglet cant and incidence angles tested.
    Keywords: AERODYNAMICS
    Type: NASA. Dryden Flight Research Facility KC-135 Winglet Program Rev.; p 171-188
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  • 48
    Publication Date: 2014-09-11
    Description: One of the objectives of the KC-135 Winglet Flight Research and Demonstration Program was to obtain experimental flight test data to verify the theoretical and wind tunnel winglet aerodynamic performance prediction methods. Good agreement between analytic, wind tunnel and flight test performance was obtained when the known differences between the tests and analyses were accounted for. The flight test measured fuel mileage improvements for a 0.78 Mach number was 3.1 percent at 8 x 10(5) pounds W/delta and 5.5 percent at 1.05 x 10(6) pounds W/delta. Correcting the flight measured data for surface pressure differences between wind tunnel and flight resulted in a fuel mileage improvement of 4.4 percent at 8 x 10(5) pounds W/delta and 7.2 percent at 1.05 x 10(6) pounds W/delta. The performance improvement obtained was within the wind tunnel test data obtained from two different wind tunnel models. The buffet boundary data obtained for the baseline configuration was in good agreement with previous established data. Buffet data for the 15 deg cant/-4 deg incidence configuration showed a slight improvement, while the 15 deg cant/-2 deg incidence and 0 deg cant/-4 deg incidence data showed a slight deterioration.
    Keywords: AERODYNAMICS
    Type: NASA. Dryden Flight Research Facility KC-135 Winglet Program Rev.; p 145-170
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  • 49
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    Publication Date: 2011-08-18
    Description: The design of a high lift system for the NASA advanced LFC airfoil designed by Pfenninger is described. The high lift system consists of both leading and trailing edge flaps. A 3 meter semispan, 1 meter chord wing model using the above airfoil and high lift system is under construction and will be tested in the NASA Langley 4 by 7 meter tunnel. This model will have two separate full span leading edge flaps (0.10c and 0.12c) and one full span trailing edge flap (0.25c). The performance of this high lift system was predicted by the NASA two dimensional viscous multicomponent airfoil program. This program was also used to predict the characteristics of the LFC airfoils developed by the Douglas Aircraft Company and Lockheed-Georgia Aircraft Company.
    Keywords: AERODYNAMICS
    Type: Laminar Flow Control; p 43-62
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  • 50
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    Publication Date: 2011-08-18
    Description: The design and construction of an advanced swept supercritical airfoil for commercial aircraft to be tested in a transonic wind tunnel is described. The swept LFC airfoil was designed for a given thickness ratio and lift coefficient, with emphasis placed on high critical Mach number with shock-free flow. It is compatible with satisfactory low speed and buffeting characteristics and minimizing the suction laminarization. Further emphasis was placed on achieving shock-free flow over a wide range of off-design conditions including trailing edge flap control. The requirements and design of the suction system and modifications to the Langley 8 foot transonic pressure tunnel is briefly described. Contouring of nonporous test section walls for free air simulation and flow quality improvements is included.
    Keywords: AERODYNAMICS
    Type: Laminar Flow Control; p 1-42
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  • 51
    Publication Date: 2011-08-18
    Description: The capability for calculating transonic flows for realistic configurations and conditions is discussed. Various phenomena which were modeled are shown to have the same order of magnitude on the influence of predicted results. It is concluded that CFD can make the following contributions to the task of correlating wind tunnel and flight test data: some effects of geometry differences and aeroelastic distortion can be predicted; tunnel wall effects can be assessed and corrected for; and the effects of model support systems and free stream nonuniformities can be modeled.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center Wind-Tunnel(Flight Correlation, 1981; p 199-215
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  • 52
    Publication Date: 2011-08-18
    Description: A method for combining the cloud detector observation results from the Global Atmospheric Sampling Program (GASP) with Knollenberg probe observations of cloud particle concentration from other programs to derive estimates of the ambient concentration of particles larger than a given size was developed. The method was applied to estimate the probability of encountering particle concentrations which would degrade the performance of laminar flow control (LFC) aircraft. It is concluded that LF loss should occur only about one percent of the time in clear air and that flight within clouds should always result in a significant loss of LF, with 90 percent LF loss occurring about one percent of the time. Preliminary estimates of cloud encounter probability are presented for four airline routes, and conclusions are presented as to the best altitudes for cloud avoidance in extratropical and tropical latitudes.
    Keywords: AERODYNAMICS
    Type: Laminar Flow Control; p 75-94
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  • 53
    Publication Date: 2011-08-18
    Description: Opportunities for improving the accuracy and reliability of wall corrections in conventional ventilated test sections are presented. The approach encompasses state-of-the-art technology in transonic computational methods combined with the measurement of tunnel-wall pressures. The objective is to arrive at correction procedures of known, verifiable accuracy that are practical within a production testing environment. It is concluded that: accurate and reliable correction procedures can be developed for cruise-type aerodynamic testing for any wall configuration; passive walls can be optimized for minimal interference for cruise-type aerodynamic testing (tailored slots, variable open area ratio, etc.); monitoring and assessment of noncorrectable interference (buoyancy and curvature in a transonic stream) can be an integral part of a correction procedure; and reasonably good correction procedures can probably be developd for complex flows involving extensive separation and other unpredictable phenomena.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center Wind-Tunnel(Flight Correlation, 1981; p 217-229
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  • 54
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    Publication Date: 2011-08-18
    Description: Correlation is defined in three different ways: comparisons of wind tunnel and/or theory with flight results; detailed studies of total vehicle drag from wind tunnel and flight tests; and attempts to understand the fundamental mechanisms of fluid flows associated with aircraft components in specific areas of the flight environment. The F-16E configuration is an outgrowth of studies conducted to produce a refined fighter wing design. Several iterations required to arrive at the combination of wing planform, camber, and twist which gives near optimum lift, drag, and high-angle-of-attack stability. Theoretical analyses were backed up by extensive experimental data to validate the design and are presented
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center Wind-Tunnel(Flight Correlation, 1981; p 159-172
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  • 55
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    Publication Date: 2011-08-18
    Description: A conventional flight-test program, which slowly and cautiously approaches more severe flight conditions, was not possible with the Orbiter. On the first flight, the Orbiter entered the atmosphere at Mach 28 and decelerated through the Mach range. (The subsonic portion of flight was also flown by another orbiter vehicle during the Approach and Landing Test Program.) Certification for the first flight was achieved by an extensive wind-tunnel test and analysis program and by restricting the flight maneuvers severely. The initial flights of the orbiter were heavily instrumented for the purpose of obtaining accurate aerodynamic data. Even without maneuvers to excite the system, the first flight provided comparisons between flight and wind-tunnel-derived predicted data in the areas of aerodynamic performance, longitudinal trim, and reaction-control jet interaction. The aerodynamic performance comparisons are presented.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center Wind-Tunnel(Flight Correlation, 1981; p 117-131
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  • 56
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    Publication Date: 2011-08-18
    Description: Flow quality is discussed. Incremental comparisons of: (1) the angle of attack, (2) the axial force coefficient, and (3) the base cavity axial force coefficient against the normal force coefficient are presented. Relative blockage determination, relative buoyancy corrections, and boundary layer transition length are discussed. Blockage buoyancy caused by tunnel model wall dynamic interaction is discussed in terms of adaptive walls. The effect of 'transonic turbulence factor' is considered.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center Wind-Tunnel(Flight Correlation, 1981; p 47-63
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  • 57
    Publication Date: 2011-08-18
    Description: A recently reported parabolized Navier-Stokes code has been employed to compute the supersonic flowfield about a spinning cone and spinning and nonspinning ogive cylinder and boattailed bodies of revolution at moderate incidence. The computations were performed for flow conditions where extensive measurements for wall pressure, boundary-layer velocity profiles, and Magnus force had been obtained. Comparisons between the computational results and experiment indicate excellent agreement for angles of attack up to 6 deg. At angles greater than 6 deg discrepancies are noted which are tentatively attributed to turbulence modeling errors. The comparisons for Magnus effects show that the code accurately predicts the effects of body shape for the selected models.
    Keywords: AERODYNAMICS
    Type: AIAA Journal; 20; Dec. 198
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  • 58
    Publication Date: 2011-08-18
    Description: (Previously cited in issue 17, p. 3111, Accession no. A80-41562)
    Keywords: AERODYNAMICS
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  • 59
    Publication Date: 2011-08-18
    Description: Conventional methods for the calculation of wall interference corrections are based on boundary conditions which require a knowledge of ventilated wall porosity parameters, and which are unsuitable for deformed walls. The method described uses a simple exponential decay of pressure distribution beyond the most upstream and downstream limits in order to evaluate Mach number and incidence corrections given by the method proposed by Papelier et al. (1978). It is found that, while the upstream contribution to incidence correction is significant, the upstream and downstream contributions to Mach number correction are negligible.
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft; 19; Dec. 198
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  • 60
    Publication Date: 2011-08-18
    Description: (Previously cited in issue 07, p. 963, Accession no. A82-19212)
    Keywords: AERODYNAMICS
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  • 61
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    Publication Date: 2011-08-18
    Description: An exact analytical solution for the velocity field, both interior and exterior, induced by an infinite right-handed helical vortex filament is derived. Due to the way the variables combine in this solution, the paper also shows that it is possible to derive a stream function for this nonaxisymmetric flow. Sample calculations of these expressions are included.
    Keywords: AERODYNAMICS
    Type: Physics of Fluids; 25; Nov. 198
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  • 62
    Publication Date: 2011-08-18
    Description: Analytical studies and laboratory experiments have been performed to evaluate the vibration response of the Space Shuttle Thermal Protection System (TPS) tiles due to the intense rocket generated acoustic noise during lift-off. The TPS tiles are mounted over the exterior of the Space Shuttle Orbiter structure through Strain Isolation Pads (SIP) which protect the tiles from thermal induced shear loads at their interface. The analytical predictions indicate that the response of a typical tile is governed by the structural vibration inputs through the SIP under the tile at frequencies below 250 Hz, and by the direct acoustic excitation over the exterior surface of the tile at frequencies above 250 Hz. An evaluation of the laboratory test data for this same tile, in which conditioned (partial) coherent output spectral analysis procedures were used, leads to exactly the same conclusion. The results demonstrate the power of conditioned spectral analysis procedures in identifying vibration response mechanisms when two or more of the inputs are highly correlated.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: Journal of Sound and Vibration; 83; July 8
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  • 63
    Publication Date: 2011-08-18
    Description: Rapid double-pulse holography was employed to obtain detailed, two-dimensional images of the shock forming during simulated flutter in a transonic flowfield. The experiment comprised a linear cascade of airfoils externally oscillated in torsion and viewed tangentially at the shock surface. Three biconvex airfoils were subjected to harmonic pitching motion about the midchord axis at a frequency of 0.53 while immersed in a Mach 0.81 flow. Failure to produce observable shocks led to use of choked flow with a Mach number near one, of which 50 holograms were taken. The images revealed a narrow shock surface with a spanwise variation in the shock properties. The method is concluded to be useful for examining transonic flowfield shocks in the presence of airfoil flutter.
    Keywords: AERODYNAMICS
    Type: AIAA Journal; 20; Aug. 198
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  • 64
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    Publication Date: 2011-08-18
    Description: Progress towards successful modelling of unsteady flows past two-dimensional oscillating airfoils is examined. Linearized, thin airfoil theory is reviewed with special regard to the vortex shedding which occurs when either the body or the flow fluctuates. A sinusoidally oscillating flat-plate airfoil is considered in terms of noncirculatory components, including boundary conditions and bound and wake vortices, respectively. Applications of linear theory to vertical airfoil oscillations and to oscillating control surfaces are described, and oscillating airfoils in subsonic and supersonic flows are investigated. Perturbations in linear solutions are explored for the occurrence of second-order effects, and trailing edge and wake effects. The effects of unsteady transonic flows are broken into nearly inviscid and strongly viscous cases, and analyses of dynamic stall and stall flutter are presented.
    Keywords: AERODYNAMICS
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  • 65
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    Publication Date: 2011-08-18
    Description: Noise emission from very small chord and very large chord airfoils was measured with eleven 0.63 cm microphones placed along a horizontal semicircle (4.57 m radius) that was centered at the leading edge of the test airfoil. The noise signals were analyzed by an automated spectrum analyzer which yielded 1/3-octave band sound pressure level spectra for each microphone, and the data were corrected to remove the effects of atmospheric attenuation and jet noise. It is found that the effect of thickness is large and must be accounted for in any fundamental airfoil noise theory that attempts to describe the noise emitted from real airfoils. Incident mean velocity gradients and compressibility must also be taken into account. The effect of thickness increases with frequency, with thick airfoils being quieter than thin ones.
    Keywords: AERODYNAMICS
    Type: AIAA Journal; 20; Mar. 198
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  • 66
    Publication Date: 2011-08-18
    Description: A simple practical method for designing antenna-feed positioning control systems for large deployable spaceborne antenna systems with flexible booms is proposed. The approach is based on the mechanical decoupling of the antenna-feed from the boom so that the positioning control system can be designed without taking boom dynamics into consideration, thus avoiding a complex infinite dimensional control problem. The basic idea is illustrated by a simple angular positional control system attached to a flexible boom restricted to torsional motion only. The application of this approach to more complex situations is discussed briefly.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
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  • 67
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    Publication Date: 2011-08-18
    Description: A method for predicting the strong interaction between the viscous and inviscid flows which occurs in flow separation is reviewed. An inverse boundary-layer procedure approximately accounts for normal pressure gradients that may be important in strongly interacting flows. Transformed boundary-layer equations are written in which the pressure gradient is set equal to the inviscid pressure gradient. As the boundary-layer edge is approached and the viscous shear and heat conduction terms vanish, the viscous flow solution is required to asymptotically approach the inviscid solution over the generalized displacement body. Attention is then focused on viscous-inviscid interacting flows with a first-order viscous formulation and constant pressure across the boundary layer. Results obtained with this procedure are presented for: (1) transitional separation bubbles near an airfoil leading edge, (2) subsonic boattail separated turbulent flow, and (3) transonic turbulent shock wave boundary-layer interaction on an axisymmetric bump configuration.
    Keywords: AERODYNAMICS
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  • 68
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    Publication Date: 2011-08-18
    Description: The role of computational aerodynamics in design is reviewed with attention given to the design process; the proper role of computations; the importance of calibration, interpretation, and verification; the usefulness of a given computational capability; and the marketing of new codes. Examples of computational aerodynamics in design are given with particular emphasis on the Highly Maneuverable Aircraft Technology. Finally, future prospects are noted, with consideration given to the role of advanced computers, advances in numerical solution techniques, turbulence models, complex geometries, and computational design procedures. Previously announced in STAR as N82-33348
    Keywords: AERODYNAMICS
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  • 69
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    Publication Date: 2013-08-29
    Description: The differences between the orbital scientific station "Salyut-7" and "Salyut-6" are discussed. It is noted that the greatest changes have occurred in the scientific instrument compartment. The changes in the food supplied to the cosmonauts are also described.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA-TM-77177 , NAS 1.15:77177
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  • 70
    Publication Date: 2017-10-02
    Description: The separation of three dimensional turbulent boundary layers from the lee of flight vehicles at high angles of attack is investigated. The separation results in dominant, large scale, coiled vortex motions that pass along the body in the general direction of the free stream. In all cases of three dimensional flow separation and reattachment, the assumption of continuous vector fields of skin friction lines and external flow streamlines, coupled with simple laws of topology, provides a flow grammar whose elemental constituents are the singular points: the nodes, spiral nodes (foci), and saddles. The phenomenon of three dimensional separation may be constrained as either a local or a global event, depending on whether the skin friction line that becomes a line of separation originates at a node or a saddle point.
    Keywords: AERODYNAMICS
    Type: AGARD High Angle-of-Attack Aerodyn.; 14 p
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  • 71
    Publication Date: 2017-10-02
    Description: The structures of three dimensional separated flow about some chosen aerodynamic components at angle of attack are synthesized, holding strictly to the notion that streamlines in the external flow (viscous plus inviscid) and skin friction lines on the body surface may be considered as trajectories having properties consistent with those of continuous vector fields. Singular points in the fields are of limited number and are classified as simple nodes and saddles. Analogous flow structures at high angles of attack about blunt and pointed bodies, straight and swept wings, etc., are discussed, highlighting the formation of spiral nodes (foci) in the pattern of the skin friction lines. How local and global three dimensional separation lines originate and form is addressed, and the characteristics of both symmetric and asymmetric leeward wakes are described.
    Keywords: AERODYNAMICS
    Type: AGARD High Angle-of-Attack Aerodyn.; 56 p
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  • 72
    Publication Date: 2017-10-02
    Description: A novel concept which was developed to provide powerful directional control effectiveness for a fighter aircraft at high angles of attack, where more traditional controls have very limited capability is discussed. The concept utilizes the energy concentrated in the strong forebody vortices (which form on slender bodies at high relative incidence) by controlling the lateral orientation of the vortices with respect to the body. The present concept seeks to utilize the inherent sensitivity of the vortex positioning and its bistable nature to an advantage allowing control of the forces which are developed. As it turns out, the direction or sense of the asymmetric vortex pair is much easier to control than to attenuate. The work which was done to develop the concept for application to an aircraft is described and is directed toward the effects of the concept on aircraft forces and moments and on the flight mechanics of the aircraft during maneuvering at high angles of attack. The objective was to utilize the side force associated with asymmetric vortices, in a controlled manner, to enhance the ability of the fighter to recover from a departure from controlled flight. The results from these water tunnel and wind tunnel experiments show that a small amount of tangential blowing along the forebody near the apex can effectively alter the forebody vortex system and generate large restoring yawing moments.
    Keywords: AERODYNAMICS
    Type: AGARD High Angle-of-Attack Aerodyn.; 22 p
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  • 73
    Publication Date: 2017-10-02
    Description: The pretest preparation necessary to define the objectives of an appropriate investigation into the jet V/STOL wind tunnel simulation and ground plane effects were examined. Low speed wind tunnel testing of V/STOL aircraft concepts to determine the aerodynamic propulsion interaction effects during the transition between hover and wingborne flight is a necessary step in the development cycle of this type of aircraft. Powered models are normally used to determine the aerodynamic performance characteristics. Several factors which influence the selection of the model concept and the engine simulator are discussed. Some of the test techniques important for this class of aircraft model are examined. Wind tunnel wall effects important to this aircraft testing with special emphasis on groundplane effects are reviewed.
    Keywords: AERODYNAMICS
    Type: AGARD Fluid Dyn. of Jets with Appl. to V(STOL; 21 p
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  • 74
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    In:  CASI
    Publication Date: 2019-06-28
    Description: The results of a 3 month preliminary design and analysis effort is presented. The configuration that emerged consists of a very stiff deployable truss structure with an overall triangular cross section having universal modules attached at the apexes. Sufficient analysis was performed to show feasibility of the configuration. An evaluation of the structure shows that desirable attributes of the configuration are: (1) the solar cells, radiators, and antennas will be mounted to stiff structure to minimize control problems during orbit maintenance and correction, docking, and attitude control; (2) large flat areas are available for mounting and servicing of equipment; (3) Large mass items can be mounted near the center of gravity of the system to minimize gravity gradient torques; (4) the trusses are lightweight structures and can be transported into orbit in one Shuttle flight; (5) the trusses are expandable and will require a minimum of EVA; and (6) the modules are anticipated to be structurally identical except for internal equipment to minimize cost.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA-TM-87521 , NAS 1.15:87521
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  • 75
    facet.materialart.
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    In:  CASI
    Publication Date: 2016-06-07
    Description: A survey has been conducted to determine the types of control strategies which have been proposed for controlling the vibrations in large space structures. From this survey several representative control strategies were singled out for detailed analyses. The application of these strategies to a simplified model of a large space structure has been simulated. These simulations demonstrate the implementation of the control algorithms and provide a basis for a preliminary comparison of their suitability for large space structure control.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA. Marshall Space Flight Center The 1982 NASA(ASEE Summer Fac. Fellowship Program; 28 p
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  • 76
    Publication Date: 2016-06-07
    Description: Fuel optimal maneuvers of spacecraft relative to a body in circular orbit are investigated using a point mass model in which the magnitude of the thrust vector is bounded. All nonsingular optimal maneuvers consist of intervals of full thrust and coast and are found to contain at most seven such intervals in one period. Only four boundary conditions where singular solutions occur are possible. Computer simulation of optimal flight path shapes and switching functions are found for various boundary conditions. Emphasis is placed on the problem of soft rendezvous with a body in circular orbit.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA. Marshall Space Flight Center The 1982 NASA(ASEE Summer Fac. Fellowship Program; 22 p
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  • 77
    Publication Date: 2016-06-07
    Description: Information on the identification and control of spacecraft is given. Maximum likelihood estimation, identification accuracy issues, steady state identifiability analysis and stochastic error with process noise are among the topics addressed.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA. Langley Research Center Structural Dyn. and Control of Large Space Struct., 1982; p 79-90
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  • 78
    Publication Date: 2016-06-07
    Description: An exact numerical calculation is provided for of linear growth and phase velocity of Kelvin-Helmholtz unstable wave modes on a supersonic jet of cylindrical cross section. An expression for the maximally unstable wavenumber of each wave mode is found. Provided a sharp velocity discontinuity exists all wave modes are unstable. A combination of rapid jet expansion and velocity shear across a jet can effectively stabilize all wave modes. The more likely case of slow jet expansion and of velocity shear at the jet surface allows wave modes with maximally unstable wavelength longer than or on the order of the jet radius to grow. The relative energy in different wave modes and effect on the jet is investigated. Energy input into a jet resulting from surface instability is discussed.
    Keywords: AERODYNAMICS
    Type: NASA. Marshall Space Flight Center The 1982 NASA(ASEE Summer Fac. Fellowship Program; 23 p
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  • 79
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    In:  Other Sources
    Publication Date: 2018-12-01
    Description: The design and goals of experimental investigations of supercritical LFC airfoils conducted in the NASA Langley 8-ft Transonic Pressure Tunnel beginning in March 1982 are reviewed. Topics addressed include laminarization aspects; flow-quality requirements; simulation of flight parameters; the setup of screens, honeycomb, and sonic throat; the design cycle; theoretical pressure distributions and shock-free limits; drag divergence and stability analysis; and the LFC suction system. Consideration is given to the LFC airfoil model, the air-flow control system, airfoil-surface instrumentation, liner design and hardware, and test options. Extensive diagrams, drawings, graphs, photographs, and tables of numerical data are provided.
    Keywords: AERODYNAMICS
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  • 80
    Publication Date: 2019-01-25
    Description: Several of the key material technology needs that were identified for large space structures are outlined. They include lightweight structural materials, materials durability in the space environment, and some special aspects of materials fabrication technology. Examples of current materials research directed toward large space structures are described. Additional research needs and opportunities are noted. A short bibliography is included of selected references that describe large space structural concepts and related technology needs in detail.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: R and D Associates Proc. of the AFOSR Spec. Conf. on Prime-Power for High Energy Space Systems, Vol. 2; 38 p
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  • 81
    Publication Date: 2019-06-28
    Description: The equations of motion for a flexible vehicle capable of arbitrary translational and rotational motions in inertial space accompanied by small elastic deformations are derived in an unabridged form. The vehicle is idealized as consisting of a single rigid body with an ensemble of mass particles interconnected by massless elastic structure. The internal elastic restoring forces are quantified in terms of a stiffness matrix. A transformation and truncation of elastic degrees of freedom is made in the interest of numerical integration efficiency. Deformation dependent terms are partitioned into a hierarchy of significance. The final set of motion equations are brought to a fully assembled first order form suitable for direct digital implementation. A FORTRAN program implementing the equations is given and its salient features described.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA-CR-188727 , NAS 1.26:188727 , CSDL-R-1582
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  • 82
    Publication Date: 2019-06-28
    Description: A study of low speed leading-edge flap design for supersonic cruise vehicle was conducted. Wings with flaps were analyzed with the aid of a newly developed subsonic wing program which provides estimates of attainable leading-edge thrust. Results indicate that the thrust actually attainable can have a significant influence on the design and that the resultant flaps can be smaller and simpler than those resulting from more conventional approaches.
    Keywords: AERODYNAMICS
    Type: NASA-CR-165843 , NAS 1.26:165843
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  • 83
    Publication Date: 2019-06-28
    Description: Three airfoils designed for helicopter rotor application were investigated in the Langley 6- by 28-inch Transonic Tunnel to determine the two dimensional aerodynamic characteristics at Mach numbers from 0.34 to 0.88 and respective Reynolds numbers from about 4.4 x 10(6) power to 9.5 x 10(6) power. The airfoils have thickness-to-chord ratios of 0.08, 0.10, and 0.12. Trailing-edge reflex was applied to minimize pitching moment. The maximum normal-force coefficient of the RC(3)-12 airfoil is from 0.1 to 0.2 higher, depending on Mach number M, than that of the NACA 0012 airfoil tested in the same facility. The maximum normal-force coefficient of the RC(3)-10 is about equal to that of the NACA 0012 at Mach numbers to 0.40 and is higher than that of the NACA 0012 at Mach numbers above 0.40. The maximum normal force coefficient of the RC(3)-08 is about 0.19 lower than that of the NACA 0012 at a Mach number of 0.35 and about 0.05 lower at a Mach number of 0.54. The drag divergence Mach number of the RC(3)-08 airfoil at normal-force coefficients below 0.1 was indicated to be greater than the maximum test Mach number of 0.88. At zero lift, the drag-divergence Mach numbers of the RC(3)-12 and the RC(3)-10 are about 0.77 and 0.82, respectively.
    Keywords: AERODYNAMICS
    Type: NASA-TP-2000 , L-14955 , NAS 1.60:2000 , AVRADCOM-TR-82-B-2
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  • 84
    Publication Date: 2019-06-28
    Description: The wind tunnel testing of an advanced technology high lift system for a wide body and a narrow body transport incorporating high aspect ratio supercritical wings is described. This testing has added to the very limited low speed high Reynolds number data base for this class or aircraft. The experimental results include the effects on low speed aerodynamic characteristics of various leading and trailing edge devices, nacelles and pylons, ailerons, and spoilers, and the effects of Mach and Reynolds numbers.
    Keywords: AERODYNAMICS
    Type: NASA-CR-3523 , NAS 1.26:3523 , ACEE-17-FR-1608
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  • 85
    Publication Date: 2019-06-28
    Description: A 2.29 m (7.5 ft.) span high-lift research model equipped with full-span leading-edge slat and part-span double-slotted trailing-edge flap was tested in the Langley 4- by 7-Meter Tunnel to determine the low speed performance characteristics of a representative high aspect ratio suprcritical wing. These tests were performed in support of the Energy Efficient Transport (EET) program which is one element of the Aircraft Energy Efficiency (ACEE) project. Static longitudinal forces and moments and chordwise pressure distributions at three spanwise stations were measured for cruise, climb, two take-off flap, and two landing flap wing configurations. The tabulated and plotted pressure distribution data is presented without analysis or discussion.
    Keywords: AERODYNAMICS
    Type: NASA-TM-83111 , NAS 1.15:83111
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  • 86
    Publication Date: 2019-06-28
    Description: Wind tunnel tests were conducted on the NASA LS(1)-0421 Mod, NACA 2412 and NASA GA(W)-2 airfoil sections at a Reynolds number of 2.2 x 10(6) and a Mach number of 0.13. Detailed measurements of flow fields associated with turbulent boundary layers of these airfoils were obtained at pre-stall, near-stall, and post-stall angles of attack. Velocity and pressure survey results over the airfoil and in the associated wake, are presented for fully attached flow conditions through the stalled flow condition. Extensive force, pressure, tuft survey, hot-film survey, local skin friction and boundary layer data are also included.
    Keywords: AERODYNAMICS
    Type: NASA-CR-3530 , NAS 1.26:3530 , AR-79-2
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  • 87
    Publication Date: 2019-06-28
    Description: The approach used to develop a broad interest in the space station within the commercial and DoD communities is outlined. Areas of maximum benefit from a space station were identified and the associated economic benefits were quantified. Results show that the space station can provide major performance benefits for 82 man-operated missions, 18 man-tended free flyer missions, and 46 OTV missions. The man-operated OVT-based benefits are $800 M per year. The cost of shuttle flights of all STS users can be reduced by $7 M per flight. The economic benefits quantified to date exceed 1.3 B per year. Combined NASA/DoD utilization of an initial space station provided economic and technical benefits. Preliminary studies of operational missions indicate a possible need for separate stations.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA-CR-173446 , NAS 1.26:173446
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  • 88
    Publication Date: 2019-06-28
    Description: A new rotor configuration called the variable camber rotor was investigated numerically for its potential to reduce helicopter control loads and improve hover performance. This rotor differs from a conventional rotor in that it incorporates a deflectable 50% chord trailing edge flap to control rotor lift, and a non-feathering (fixed) forward portion. Lift control is achieved by linking the blade flap to a conventional swashplate mechanism; therefore, it is pilot action to the flap deflection that controls rotor lift and tip path plane tilt. This report presents the aerodynamic characteristics of the flapped and unflapped airfoils, evaluations of aerodynamics techniques to minimize flap hinge moment, comparative hover rotor performance and the physical concepts of the blade motion and rotor control. All the results presented herein are based on numerical analyses. The assessment of payoff for the total configuration in comparison with a conventional blade, having the same physical characteristics as an H-34 helicopter rotor blade was examined for hover only.
    Keywords: AERODYNAMICS
    Type: NASA-CR-3503 , NAS 1.26:3503
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  • 89
    Publication Date: 2019-06-28
    Description: A wind tunnel investigation of an advanced-technology airfoil was conducted in the Langley 0.3-Meter Transonic Cryogenic Tunnel (TCT). This investigation represents the first in a series of NASA/U.X. industry two dimensional airfoil studies to be completed in the Advanced Technology Airfoil Test program. Test temperature was varied from ambient to about 100 K at pressures ranging from about 1.2 to 6.0 atm. Mach number was varied from about 0.40 to 0.80. These variables provided a Reynolds number (based on airfoil chord) range from about .0000044 to .00005. This investigation was specifically designed to: (1) test a Boeing advanced airfoil from low to flight-equivalent Reynolds numbers; (2) provide the industry participant (Boeing) with experience in cryogenic wind-tunnel model design and testing techniques; and (3) demonstrate the suitability of the 0.3-m TCT as an airfoil test facility. All the objectives of the cooperative test were met. Data are included which demonstrate the effects of fixed transition, Mach number, and Reynolds number on the aerodynamic characteristics of the airfoil. Also included are remarks on the model design, the model structural integrity, and the overall test experience.
    Keywords: AERODYNAMICS
    Type: NASA-TM-81922 , L-15011 , NAS 1.15:81922
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  • 90
    Publication Date: 2019-06-28
    Description: Low-speed wind-tunnel tests were performed on a generic forward-swept-wing aircraft model in the 7- by 10-Foot Wind Tunnel (No. 2) at Ames Research Center. The effects of various configurational changes and control-surface deflections on the performance of the model were measured. Six-component force measurements were augmented by flow-visualization photographs, using both surface oil-flow and tufts. It was found that the tendency toward premature root separation on the forward-swept wing could be reduced by use of either canards or leading-edge wing strakes and that differential canard deflections can be used to produce a direct side-force control.
    Keywords: AERODYNAMICS
    Type: SAE PAPER 821467
    Format: text
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  • 91
    Publication Date: 2019-06-28
    Description: A new analysis for designing dual-layer shields is presented which is based on energy and momentum conservation, fundamental electromagnetic radiation physics, and the observation of results of extensive experimental impact studies performed at relatively low velocities (near 7 km/s). An important finding is that most of the kinetic energy of a meteoroid striking a dual-layer shield is expended as radiation at the stagnation zone on the face plate of the underlying structure. Systematic procedures for evaluating the response of shield designs for a given impact threat are described. It is noted that similar applications of the analysis can be employed to support a mathematically rigorous procedure for optimum shield design.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: (ISSN 0273-1177)
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  • 92
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    In:  CASI
    Publication Date: 2019-06-28
    Description: A flight test survey of pressures measured on wing, pylon, and nacelle surfaces and of the operating loads on Boeing 747/Pratt & Whitney JT9D-7A nacelles was made to provide information on airflow patterns surrounding the propulsion system installations and to clarify processes responsible for inservice deterioration of fuel economy. Airloads at takeoff rotation were found to be larger than at any other normal service condition because of the combined effects of high angle of attack and high engine airflow. Inertial loads were smaller than previous estimates indicated. A procedure is given for estimating inlet airloads at low speeds and high angles of attack for any underwing high bypass ratio turbofan installation approximately resembling the one tested. Flight procedure modifications are suggested that may result in better fuel economy retention in service. Pressures were recorded on the core cowls and pylons of both engine installations and on adjacent wing surfaces for use in development of computer codes for analysis of installed propulsion system aerodynamic drag interference effects.
    Keywords: AERODYNAMICS
    Type: NASA-CR-165807 , NAS 1.26:165807 , D6-49360
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  • 93
    Publication Date: 2019-06-28
    Description: A full scale prototype flexible radiator panel was designed, built and tested. The panel, has approximately 173 sq ft of radiating area and is designed to reject 1.33 kW of heat to a 0 F sink with a 100 F fluid inlet. The panel is constructed from a flexible Teflon/silver mesh fin surrounding 1/8 inch Teflon tubes. The prototype panel is stowed on a 10 inch diameter by 4 foot wide drum. (It rolls up to a diameter of 17 inches when fully stowed). Deployment of the soft tube prototype is via two four inch diameter Kevlar/Mylar inflation tubes with flat springs incorporated in each tube. Nitrogen is normally used for the deployment with approximately 1 psi required. The springs retract the panels when the inflation tubes are deflated. Another method of deployment available for the soft tube flexible is a motor driven deployable boom. This eliminates the need for expendables when the panel area is varied during the mission for heat load control. The soft tube panel is designed for a 90% probability of no punctured tube in a 30 day mission. The acceptable working fluids for this soft tube flexible are Coolanol 15, Coolanol 20 and Glycol/water (a eutectic mixture).
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA-CR-171766 , NAS 1.26:171766 , REPT-2-19200/3R-1062B
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  • 94
    Publication Date: 2019-06-28
    Description: Two flexible, deployable/retraction radiators were designed and fabricated. The two radiator panels are distinguishable by their mission life design. One panel is designed with a 90 percent probability of withstanding the micrometeoroid environment of a low earth orbit for 30 days. This panel is designated the soft tube radiator after the PFA Teflon tubes which distribute the transport fluid over the panel. The second panel is designed with armored flow tubes to withstand the same micrometeoroid environment for 5 years. It is designated the hard tube radiator after its stainless steel flow tubes. The thermal performance of the radiators was tested under anticipated environmental conditions. The two deployment systems of the radiators were evaluated in a thermal vacuum environment.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA-CR-171764 , NAS 1.26:171764 , REPT-2-32300/IR-03
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  • 95
    facet.materialart.
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    In:  CASI
    Publication Date: 2019-06-28
    Description: The soft tube radiator subsystem is described including applicable system requirements, the design and limitations of the subsystem components, and the panel manufacturing method. The soft tube radiator subsystem is applicable to payloads requiring 1 to 12 kW of heat rejection for orbital lifetimes per mission of 30 days or less. The flexible radiator stowage volume required is about 60% and the system weight is about 40% of an equivalent heat rejection rigid panel. The cost should also be considerably less. The flexible radiator is particularly suited to shuttle orbiter sortie payloads and also whose mission lengths do not exceed the 30 day design life.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA-CR-171765 , NAS 1.26:171765 , REPT-2-19200/3R-1195B
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  • 96
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    In:  Other Sources
    Publication Date: 2019-06-28
    Description: A two-part study was performed to design inlets for high-speed propfan installation. The first part was a parametric study to select promising inlet concepts. A wide range of inlet geometries was examined and evaluated - primarily on the basis of cruise thrust and fuel burn performance. Two inlet concepts were than chosen for more detailed design studies - one apropriate to offset engine/gearbox arrangements and the other to in-line arrangements. In the second part of this study, inlet design points were chosen to optimize the net installed thrust, and detailed design of the two inlet configurations was performed. An analytical methodology was developed to account for propfan slipstream effects, transonic flow efects, and three-dimensional geometry effects. Using this methodology, low drag cowls were designed for the two inlets.
    Keywords: AERODYNAMICS
    Type: SAE PAPER 821359
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  • 97
    Publication Date: 2019-06-28
    Description: A computer code base on an improved vortex filament/vortex core method for predicting aerodynamic characteristics of slender wings with edge vortex separations is developed. The code is applicable to camber wings, straked wings or wings with leading edge vortex flaps at subsonic speeds. The prediction of lifting pressure distribution and the computer time are improved by using a pair of concentrated vortex cores above the wing surface. The main features of this computer program are: (1) arbitrary camber shape may be defined and an option for exactly defining leading edge flap geometry is also provided; (2) the side edge vortex system is incorporated.
    Keywords: AERODYNAMICS
    Type: NASA-CR-165902 , NAS 1.26:165902
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  • 98
    Publication Date: 2019-06-28
    Description: The purpose of this study was to determine if advanced supercritical wings incur higher trim drag values at cruise conditions than current wide body technology wings. Relative trim drag increments were measured in an experimental wind tunnel investigation conducted in the Langley 8 Foot Transonic Pressure Tunnel. The tests utilized a high aspect ratio supercritical wing and a wide body aircraft wing, in conjunction with five different horizontal tail configurations, mounted on a representative wide body fuselage. The three low tail and two T-tail configurations were designed to measure the effects of horizontal tail size, location, and camber on the trim drag increments for the two wings. Longitudinal force and moment data were taken at a Mach number of 0.82 and design cruise lift coefficients for the wide body and supercritical wings of 0.45 and 0.55, respectively. The data indicate that the supercritical wing does not have significantly higher trim drag than the wide body wing. A reduction in tail size, combined with relaxed static stability, produced trim drag reductions for both wings. The cambered tails had higher trim drag increments than the symmetrical tails for both wings, and the T-tail configurations had lower trim drag increments than the low tail configurations.
    Keywords: AERODYNAMICS
    Type: NASA-TP-2071 , L-15315 , NAS 1.60:2071
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  • 99
    Publication Date: 2019-06-28
    Keywords: AERODYNAMICS
    Type: NASA-CR-184996 , NAS 1.26:184996
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  • 100
    Publication Date: 2019-06-28
    Description: A computer code, XSECT, has been developed to generate fuselage cross sections from a given area distribution and wing definition. The cross sections are generated to match the wing definition while conforming to the area requirement. An iterative procedure is used to generate each cross section. Fuselage area balancing may be included in this procedure if desired. The code is intended as an aid for engineers who must first design a wing under certain aerodynamic constraints and then design a fuselage for the wing such that the contraints remain satisfied. This report contains the information necessary for accessing and executing the code, which is written in FORTRAN to execute on the Cyber 170 series computers (NOS operating system) and produces graphical output for a Tektronix 4014 CRT. The LRC graphics software is used in combination with the interface between this software and the PLOT 10 software.
    Keywords: AERODYNAMICS
    Type: NASA-TM-83218 , NAS 1.15:83218
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