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  • AERODYNAMICS  (2,110)
  • 1975-1979  (2,110)
  • 101
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    Aerodynamic characteristics of wheelchairs (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The overall aerodynamic drag characteristics of a conventional wheelchair were defined and the individual drag contributions of its components were determined. The results show that a fiftieth percentile man sitting in the complete wheelchair would experience an aerodynamic drag coefficient on the order of 1.4.
    Keywords: AERODYNAMICS
    Type: NASA-TM-80191 , L-13240
    Format: application/pdf
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  • 102
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    Effects of fuselage forebody geometry on low-speed lateral-directional characteristics of twin-tail fighter model at high angles of attack (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Low-speed, static wind-tunnel tests were conducted to explore the effects of fighter fuselage forebody geometry on lateral-directional characteristics at high angles of attack and to provide data for general design procedures. Effects of eight different forebody configurations and several add-on devices (e.g., nose strakes, boundary-layer trip wires, and nose booms) were investigated. Tests showed that forebody design features such as fineness ratio, cross-sectional shape, and add-on devices can have a significant influence on both lateral-directional and longitudinal aerodynamic stability. Several of the forebodies produced both lateral-directional symmetry and strong favorable changes in lateral-directional stability. However, the same results also indicated that such forebody designs can produce significant reductions in longitudinal stability near maximum lift and can significantly change the influence of other configuration variables. The addition of devices to highly tailored forebody designs also can significantly degrade the stability improvements provided by the clean forebody.
    Keywords: AERODYNAMICS
    Type: NASA-TP-1592 , L-13270
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  • 103
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    An exploratory investigation of the STOL landing maneuver (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The parameters influencing the STOL landing are identified and their effect on the ease and quality of the flare maneuver is discussed. Data from actual landings, supported by pilot commentary and pilot opinion rating, are analyzed. Hypotheses concerning the prediction of STOL handling qualities in the flare are proposed, and suggestions for future research are presented.
    Keywords: AERODYNAMICS
    Type: NASA-CR-3191 , AMS-1231-T
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  • 104
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    Transonic aerodynamic characteristics of a supersonic cruise aircraft research model with the engines suspended above the wing (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The influence of upper-surface nacelle exhaust flow on the aerodynamic characteristics of a supersonic cruise aircraft research configuration was investigated in a 16 foot transonic tunnel over a range of Mach numbers from 0.60 to 1.20. The arrow-wing transport configuration with engines suspended over the wing was tested at angles of attack from -4 deg to 6 deg and jet total pressure ratios from 1 to approximately 13. Wing-tip leading edge flap deflections of -10 deg to 10 deg were tested with the wing-body configuration. Various nacelle locations (chordwise, spanwise, and vertical) were tested over the ranges of Mach numbers, angles of attack, and jet total-pressure ratios. The results show that reflecting the wing-tip leading edge flap from 0 deg to -10 deg increased the maximum lift-drag ratio by 1.0 at subsonic speeds. Jet exhaust interference effects were negligible.
    Keywords: AERODYNAMICS
    Type: NASA-TM-80145 , L-12811
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  • 105
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    Inclusion of unsteady aerodynamics in longitudinal parameter estimation from flight data (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A simple vortex system, used to model unsteady aerodynamic effects into the rigid body longitudinal equations of motion of an aircraft, is described. The equations are used in the development of a parameter extraction algorithm. Use of the two parameter-estimation modes, one including and the other omitting unsteady aerodynamic modeling, is discussed as a means of estimating some acceleration derivatives. Computer generated data and flight data, used to demonstrate the use of the parameter-extraction algorithm are studied.
    Keywords: AERODYNAMICS
    Type: NASA-TP-1536 , L-13009
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  • 106
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    Summary of low-speed longitudinal aerodynamics of two powered close-coupled wing-canard fighter configurations (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Investigations of the low speed longitudinal characteristics of two powered close coupled wing-canard fighter configurations are discussed. Data obtained at angles of attack from -2 deg to 42 deg, Mach numbers from 0.12 to 0.20, nozzle and flap deflections from 0 deg to 40 deg, and thrust coefficients from 0 to 2.0, to represent both high angle of attack subsonic maneuvering characteristics and conventional takeoff and landing characteristics are examined. Data obtained with the nozzles deflected either 60 deg or 90 deg and the flaps deflected 60 deg to represent vertical or short takeoff and landing characteristics are discussed.
    Keywords: AERODYNAMICS
    Type: NASA-TP-1535 , L-13157
    Format: application/pdf
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  • 107
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    Pitot pressure measurements in flow fields behind circular-arc nozzles with exhaust jets at subsonic free-stream Mach numbers (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The flow field behind a circular arc nozzle with exhaust jet was studied at subsonic free stream Mach numbers. A conical probe was used to measure the pitot pressure in the jet and free stream regions. Pressure data were recorded for two nozzle configurations at nozzle pressure ratios of 2.0, 2.9, and 5.0. At each set of test conditions, the probe was traversed from the jet center line into the free stream region at seven data acquisition stations. The survey began at the nozzle exit and extended downstream at intervals. The pitot pressure data may be applied to the evaluation of computational flow field models, as illustrated by a comparison of the flow field data with results of inviscid jet plume theory.
    Keywords: AERODYNAMICS
    Type: NASA-TM-80169 , L-13060
    Format: application/pdf
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  • 108
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    Application of supersonic linear theory and hypersonic impact methods to three nonslender hypersonic airplane concepts at Mach numbers from 1.10 to 2.86 (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Aerodynamic predictions from supersonic linear theory and hypersonic impact theory were compared with experimental data for three hypersonic research airplane concepts over a Mach number range from 1.10 to 2.86. The linear theory gave good lift prediction and fair to good pitching-moment prediction over the Mach number (M) range. The tangent-cone theory predictions were good for lift and fair to good for pitching moment for M more than or equal to 2.0. The combined tangent-cone theory predictions were good for lift and fair to good for pitching moment for M more than or equal to 2.0. The combined tangent-cone/tangent-wedge method gave the least accurate prediction of lift and pitching moment. The zero-lift drag was overestimated, especially for M less than 2.0. The linear theory drag prediction was generally poor, with areas of good agreement only for M less than or equal to 1.2. For M more than or equal to 2.), the tangent-cone method predicted the zero-lift drag most accurately.
    Keywords: AERODYNAMICS
    Type: NASA-TP-1539 , L-13142
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  • 109
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    Aerodynamic characteristics of a hypersonic research airplane concept having a 70 deg swept double-delta wing at Mach numbers from 0.80 to 1.20, with summary of data from 0.20 to 6.0 (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The static longitudinal, lateral, and directional stability characteristics of a hypersonic research airplane concept having a 70 deg swept double-delta wing were investigated. Force tests were conducted in the Langley 8 foot transonic pressure tunnel for a Reynolds number (based on fuselage length) range of 6.30 x 10 to the 6th power to 7.03 x 10 to the 6th power, at angles of attack from about -4 deg to 23 deg, and at angles of sideslip of 0 deg and 5 deg. The configuration variables included the wing planform, tip fins, the center vertical tail, and scramjet engine modules. Variations of the more important aerodynamic parameters with Mach number for Mach numbers from 0.20 to 6.0 are summarized. A state-of-the-art example of theoretically predicting performance parameters and static longitudinal and directional stability over the Mach number range is included.
    Keywords: AERODYNAMICS
    Type: NASA-TP-1552 , L-13158
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  • 110
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    An improved Woodward's panel method for calculating leading-edge and side-edge suction forces at subsonic and supersonic speeds (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Woodward's panel method for subsonic and supersonic flow was improved by employing control points determined by exactly matching two-dimensional pressure at a finite number of points. The results show great improvement in the predicted pressure distribution of a flapped airfoil. With the paneling scheme of cosine law in both chordwise and spanwise directions, the method is shown to accurately predict leading edge and side edge suction forces of various configurations in subsonic and supersonic flow.
    Keywords: AERODYNAMICS
    Type: NASA-CR-3205 , CRINC-FRL-266-3
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  • 111
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    Rotary balance data for a typical single-engine general aviation design for an angle-of-attack range of 8 degrees to 35 degrees, 3. Effect of wing leading-edge modifications, model A (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Aerodynamic characteristics obtained in a rotational flow environment utilizing a rotary balance located in the Langley spin tunnel are presented in plotted form for a 1/5 scale, single-engine, low-wing, general aviation airplane model. The configurations tested included the basic airplane, sixteen wing leading-edge modifications and lateral-directional control settings. Data are presented for all configurations without analysis for an angle of attack range of 8 deg to 35 deg and clockwise and counter-clockwise rotations covering an Omega b/2v range from 0 to 0.85. Also, data are presented above 35 deg of attack for some configurations.
    Keywords: AERODYNAMICS
    Type: NASA-CR-3102
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  • 112
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    A program for calculating load coefficient matrices utilizing the force summation method, L218 (LOADS). Volume 1: Engineering and usage (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The LOADS program L218, a digital computer program that calculates dynamic load coefficient matrices utilizing the force summation method, is described. The load equations are derived for a flight vehicle in straight and level flight and excited by gusts and/or control motions. In addition, sensor equations are calculated for use with an active control system. The load coefficient matrices are calculated for the following types of loads: translational and rotational accelerations, velocities, and displacements; panel aerodynamic forces; net panel forces; shears and moments. Program usage and a brief description of the analysis used are presented. A description of the design and structure of the program to aid those who will maintain and/or modify the program in the future is included.
    Keywords: AERODYNAMICS
    Type: NASA-CR-2853 , D6-44462-VOL-1
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  • 113
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    Wind tunnel force and pressure tests of a 21% thick general aviation airfoil with 20% aileron, 25% slotted flap and 10% slot-lip spoiler (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Force and surface pressure distributions were measured for the 21% LS(1)-0421 modified airfoil fitted with 20% aileron, 25% slotted flap and 10% slot lip spoiler. All tests were conducted at a Reynolds number of 2.2 x 10 to the 6th power and a Mach number of 0.13. The lift, drag, pitching moments, control surface normal force and hinge moments, and surface pressure distributions are included in the results. Incremental performance of flap and aileron are discussed and compared to the GA(W)-2 airfoil. Spoiler control which shows a slight reversal tendency at high alpha, is examined.
    Keywords: AERODYNAMICS
    Type: NASA-CR-3081 , WSU-AR-77-6
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  • 114
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    Design and wind tunnel tests of winglets on a DC-10 wing (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Results are presented of a wind tunnel test utilizing a 4.7 percent scale semi-span model in the Langley Research Center 8-foot transonic pressure wind tunnel to establish the cruise drag improvement potential of winglets as applied to the DC-10 wide body transport aircraft. Winglets were investigated on both the DC-10 Series 10 (domestic) and 30/40 (intercontinental) configurations and compared with the Series 30/40 configuration. The results of the investigation confirm that for the DC-10 winglets provide approximately twice the cruise drag reduction of wing-tip extensions for about the same increase in bending moment at the wing fuselage juncture. Furthermore, the winglet configurations achieved drag improvements which were in close agreement to analytical estimates. It was observed that relatively small changes in wing-winglet tailoring effected large improvements in drag and visual flow characteristics. All final winglet configurations exhibited visual flow characteristics on the wing and winglets
    Keywords: AERODYNAMICS
    Type: NASA-CR-3119
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  • 115
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    Multicyclic Controllable Twist Rotor Data Analysis (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Rsults provide functional relationship between rotor performance, blade vibratory loads and dual control settings and indicate that multicyclic control produced significant reductions in blade flatwise bending moments and blade root actuator control loads. Higher harmonic terms of servo flap deflection were found to be most pronounced in flatwise bending moment, transmission vertical vibration and pitch link vibratory load equations. The existing test hardware represents a satisfactory configuration for demonstrating MCTR technology and defining a data base for additional wind tunnel testing.
    Keywords: AERODYNAMICS
    Type: NASA-CR-152251 , R-1562
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  • 116
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    Simulation of the pressure field near a jet by randomly distributed vortex rings (1979)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: Fluctuations of the pressure field in the vicinity of a jet are simulated numerically by a flow model consisting of axially symmetric vortex rings with viscous cores submerged in a uniform stream. The time interval between the shedding of successive vortices is taken to be a random variable with a probability distribution chosen to match that from experiments. It is found that up to 5 diameters downstream of the jet exit, statistics of the computed pressure field are in good agreement with experimental results. Statistical comparisons are provided for the overall sound pressure level, the peak amplitude, and the Strouhal number based on the peak frequency of the pressure signals.
    Keywords: AERODYNAMICS
    Type: AIAA Journal; 17; June 197
    Format: text
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  • 117
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    Hysteresis zone or locus - Aerodynamic of bulbous based bodies at low speeds (1979)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: Experimental data are presented which seem to suggest that a well-defined hysteresis locus on bulbous based bodies at low speeds does not exist. Instead, if the experiment is repeated several times, the entire hysteresis region seems to fill with data rather than trace out a specific hysteresis locus. Data obtained on an oscillating model even at low reduced frequencies may be well defined but when applied to arbitrary motion lead to less accurate results than desired.
    Keywords: AERODYNAMICS
    Type: AIAA Journal; 17; June 197
    Format: text
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  • 118
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    Aircraft wake flow effect and horizontal tail buffet (1979)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: As part of a program to investigate the fluctuating pressure distribution and response behavior of a fighter aircraft in transonic maneuver, an F-5A scale model has previously been tested in an 11-ft transonic wind tunnel. The model, with a number of static and dynamic pressure transducers imbedded in the lifting surfaces was tested at various angles of attack up to 16 deg. In this paper, test results of particular interest to wake flow and horizontal tail buffet are described. It is shown that the dynamic pressure data on the tail surface at the specified flight conditions serve to determine the local dynamic loads. They also influence the control performance of the aircraft under maneuver conditions where buffet is encountered. The data presented demonstrate a number of contributing factors that affect the tail dynamic pressures in the transonic regime.
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft; 16; Apr. 197
    Format: text
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  • 119
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    Flow visualization studies of a general research fighter model employing a strake-wing concept at subsonic speeds (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A systematic wind tunnel study was conducted in the Langley high-speed 7 by 10 foot tunnel to document, by oil-flow photographs, the surface flow patterns for configurations incorporating strake-wing geometries indicative of current and proposed maneuvering aircraft. The configurations employed combinations of strakes with reflexed planforms having exposed spans of 10 percent, 20 percent, and 30 percent of the reference wing span and wings with trapezoidal planforms having leading-edge sweep angles of approximately 30 deg, 44 deg, and 60 deg. Tests were conducted at Mach numbers of 0.3 and 0.5 and at angles of attack ranging from approximately 5 deg to 30 deg in 5 deg increments at 0 deg sideslip. The configurations incorporating the strake-wing geometries exhibited more organized flow patterns with smaller asymmetries to higher angles of attack than the corresponding configurations incorporating the wing-alone geometries did.
    Keywords: AERODYNAMICS
    Type: NASA-TM-80057 , L-12673
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  • 120
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    Bumblebee program: Aerodynamic data. Part 3: Pressure fields at Mach numbers 1.5 and 2.0 (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A large amount of fundamental aerodynamic missile data, which were stored for a number of years at the Applied Physics Laboratory, are reported. Data that supplements the M = 2.0 flow field data are provided. The Mach number effect by means of pressure fields only, at M = 1.5 and 2.0, and at angles of attack up to 23 deg at a mid-body station where a wing might be located is described.
    Keywords: AERODYNAMICS
    Type: NASA-CR-3116
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  • 121
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    Flight investigation of piloting techniques and crosswind limitations using a research type crosswind landing gear (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A research-type crosswind landing gear was tested in a flight program which used a light STOL transport in strong crosswind conditions. The research-type crosswind landing gear used enabled the airplane to land to crosswinds up to a magnitude of 25 to 30 knots. Three modes of landing-gear operation were investigated: preset, automatic, and castor (passive self-alignment). Actual test data and histograms are given for the 195 'visual flight rules' crosswind landings made.
    Keywords: AERODYNAMICS
    Type: NASA-TP-1423 , L-12682
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  • 122
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    The influence of sweep on the aerodynamic loading of an oscillating NACA 0012 airfoil. Volume 1: Technical report (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Aerodynamic experiments were performed on an oscillating NACA 0012 airfoil utilizing a tunnel-spanning wing in both unswept and 30 degree swept configurations. The airfoil was tested in steady state and in oscillatory pitch about the quarter chord. The unsteady aerodynamic loading was measured using pressure transducers along the chord. Numerical integrations of the unsteady pressure transducer responses were used to compute the normal force, chord force, and moment components of the induced loading. The effects of sweep on the induced aerodynamic load response was examined. For the range of parameters tested, it was found that sweeping the airfoil tends to delay the onset of dynamic stall. Sweeping was also found to reduce the magnitude of the unsteady load variation about the mean response. It was determined that at mean incidence angles greater than 9 degrees, sweep tends to reduce the stability margin of the NACA 0012 airfoil; however, for all cases tested, the airfoil was found to be stable in pure pitch. Turbulent eddies were found to convect downstream above the upper surface and generate forward-moving acoustic waves at the trailing edge which move upstream along the lower surface.
    Keywords: AERODYNAMICS
    Type: NASA-CR-3092
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  • 123
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    Evaluation of the discrete vortex wake cross flow model using vector computers. Part 1: Theory and application (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The current program had the objective to modify a discrete vortex wake method to efficiently compute the aerodynamic forces and moments on high fineness ratio bodies (f approximately 10.0). The approach is to increase computational efficiency by structuring the program to take advantage of new computer vector software and by developing new algorithms when vector software can not efficiently be used. An efficient program was written and substantial savings achieved. Several test cases were run for fineness ratios up to f = 16.0 and angles of attack up to 50 degrees.
    Keywords: AERODYNAMICS
    Type: NASA-CR-152270 , TRW-30584-6001-RU-00-PT-1
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  • 124
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    Aerodynamic design and analysis of the AST-200 supersonic transport configuration concept (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The design and analysis of a supersonic transport configuration was conducted using linear theory methods in conjunction with appropriate constraints. Wing optimization centered on the determination of the required twist and camber and proper integration of the wing and fuselage. Also included in the design are aerodynamic refinements to the baseline wing thickness distribution and nacelle shape. Analysis to the baseline and revised configurations indicated an improvement in lift-to-drag ratio of 0.36 at the Mach 2.7 cruise condition. Validation of the design is planned through supersonic wing tunnel tests.
    Keywords: AERODYNAMICS
    Type: NASA-CR-159051
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  • 125
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    Wind-tunnel force and flow visualization data at Mach numbers from 1.6 to 4.63 for a series of bodies of revolution at angles of attack from minus 4 deg to 60 deg (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Flow visualization and force data for a series of six bodies of revolution are presented without analysis. The data were obtained in the Langley Unitary Plan wind tunnel for angles of attack from -4 deg to 60 deg. The Reynolds number used for these tests was 6,600,000 per meter.
    Keywords: AERODYNAMICS
    Type: NASA-TM-78813 , L-12639
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  • 126
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    Onset of condensation effects with an NACA 0012-64 airfoil tested in the Langley 0.3-meter transonic cryogenic tunnel (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The onset of condensation effects as determined by varying the stagnation temperature was found to correlate better with the amount of supercooling in the free stream than it did with the supercooling in the region of maximum local Mach number over the air foil. Effects in the pressure distribution over the air foil were seen to appear over its entire length at nearly the same total temperature. Both observations suggest that heterogeneous nucleation does occur in the free stream. The benefits realized from supercooling are presented in terms of increased Reynolds number capability at a given tunnel total pressure and reduced drive-fan power and liquid nitrogen consumption if Reynolds number is held constant. Depending on total pressure and free-stream Mach number, these three benefits are found to vary respectively from 8 to 19 percent, 12 to 24 percent, and 9 to 19 percent. The data analysis and error estimates are given.
    Keywords: AERODYNAMICS
    Type: NASA-TP-1385 , L-12581
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  • 127
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    Symmetrical and Asymmetrical separations about a yawed cone (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Three-dimensional flow separations about a 5 degree (semiapex angle, theta sub C), 1.4 m long, circular cone up to moderately high relative incidence, alpha/theta sub C approximately 5, were studied in the Mach number range 0.3 M sub infinity 1.8. The cone was tested in the Ames 1.8 by 1.8 m wind tunnel at Reynolds numbers, R sub L infinity, based on the cone length, L, from 4.5 times 10 to the 6th power to 13.5 times 10 to the 6th power, under nominally zero heat transfer conditions. Overall forces and mean surface pressures were compared with earlier measurements. Supportive three-dimensional laser velocimeter measurements of mean and fluctuating velocity in a slightly asymmetric vortex wake about a slender tangent ogive cylinder at incidence having respective nose and overall body fineness ratios of 3.5 and 12, are included.
    Keywords: AERODYNAMICS
    Type: AGARD High Angle of Attack Aerodyn.; 27 p
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  • 128
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    Surface pressure data on a series of conical forebodies at Mach numbers from 1.70 to 4.50 and combined angles of attack and sideslip (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Tabulated surface pressure data for a series of forebodies which have analytically defined cross sections and are based on a 20 degs half-angle cone are presented without analysis. Five of the cross sections were ellipses having axis ratios of 3/1, 2/1, 1/1, 1/2, and 1/3. The sixth cross section was defined by a curve having a single lobe. The data generally cover angles of attack from -5 degs to 20 degs at angles of sideslip from 0 degs to 5 degs for Mach numbers of 1.70, 2.50, 3.95, and 4.50 at a constant Reynolds number.
    Keywords: AERODYNAMICS
    Type: NASA-TM-78808
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  • 129
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    Evaluation of the discrete vortex wake cross flow model using vector computers. Part 2: User's manual for DIVORCE (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The users manual for the Discrete Vortex Cross flow Evaluator (DIVORCE) computer program is presented. DIVORCE was developed in FORTRAN 4 for the DCD 6600 and CDC 7600 machines. Optimal calls to a NASA vector subroutine package are provided for use with the CDC 7600.
    Keywords: AERODYNAMICS
    Type: NASA-CR-152271 , TRW-30584-6002-RU-00-PT-2
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    Bumblebee program, aerodynamic data. Part 2: Flow fields at Mach number 2.0 (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Available flow field data which can be used in validating theoretical procedures for computing flow fields around supersonic missiles are presented. Tabulated test data are given which define the flow field around a conical-nosed cylindrical body in a crossflow plane corresponding to a likely tail location. The data were obtained at a Mach number of 2.0 for an angle of attack of 0 to 23 degrees. The data define the flow field for cases both with and without a forward wing present.
    Keywords: AERODYNAMICS
    Type: NASA-CR-3115
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  • 131
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    Extended analytical study of the free-wing/free-trimmer concept (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The free wing/free trimmer concept was analytically studied in order to: (1) compare the fore and aft trimmer configurations on the basis of equal lift capability, rather than equal area; (2) assess the influence of tip mounted aft trimmers, both free and fixed, on the lateral directional modes and turbulence responses; (3) examine the feasibility of using differential tip mounted trimmer deflection for lateral control; (4) determine the effects of independent fuselage attitude on the lateral directional behavior; and (5) estimate the influence of wing sweep on dynamic behavior and structural weight. Results indicate that the forward trimmer concept is feasible with the reduced size examined, but it remains inferior to the aft trimmer in every respect except structural weight. Differential motion of the aft trimmer is found to provide powerful lateral control; while the effect of fuselage deck angle is a reduction of the dutch roll damping ratio for nose-down attitudes.
    Keywords: AERODYNAMICS
    Type: NASA-CR-3135
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  • 132
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    Calculations of transonic boattail flow at small angle of attack (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A transonic flow past a boattailed afterbody under a small angle of attack was examined. It is known that the viscous effect offers significant modifications of the pressure distribution on the afterbody. Thus, the formulation for the inviscid flow was based on the consideration of a flow past a nonaxisymmetric body. The full three dimensional potential equation was solved through numerical relaxation, and quasi-axisymmetric boundary layer calculations were performed to estimate the displacement effect. It was observed again that the viscous effects were not negligible. The trend of the final results agreed well with the experimental data.
    Keywords: AERODYNAMICS
    Type: NASA-CR-158471 , ME-TN-395-6 , UILU-ENG-79-4001
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  • 133
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    Structure of the Turbulent Separated Flow Around a Stalled Airfoil (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Hot-wire measurements were made in the boundary layer, the separated region, and the near wake for flow past a NACA 4412 airfoil at maximum lift. The Reynolds number based on chord was 1,500,000. Special care was taken to achieve a two-dimensional mean flow. Data were obtained at several thousand locations in the flow field. These data include intermittency, two components of mean velocity, and mean values for three double, four triple, and five quadruple products of two velocity fluctuations. No information was obtained about the third (spanwise) velocity component. Smoothing and interpolating routines were used to determine intermittency, two components of mean velocity, and mean values of three double, four triple, and five quadruple products of two velocity fluctuations on a fine rectangular mesh aligned with the airfoil chord. The data are presented in contour plots, in three-dimensional plots, and in tabular form. The format used to store the experimental data in digital form is described and a computer program which illustrates how this data can be accessed is presented.
    Keywords: AERODYNAMICS
    Type: NASA-CR-152263
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  • 134
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    Aerodynamic heating to representative SRB and ET protuberances (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Heating data and data scaling methods which can be used on representative solid rocket booster and external tank (ET) protuberances are described. Topics covered include (1) ET geometry and heating points; (2) interference heating test data (51A); (3) heat transfer data from tests FH-15 and FH-16; (4) individual protuberance data; and (5) interference heating of paint data from test IH-42. A set of drawings of the ET moldline and protuberances is included.
    Keywords: AERODYNAMICS
    Type: NASA-CR-161198 , RTR-029-1
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  • 135
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    Generalization of analytical tools for helicopter-rotor airfoils (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A state-of-the-art finite difference boundary-layer program incorporated into the NYU Transonic Analysis Program is described. Some possible treatments for the trailing edge region were investigated. Findings indicate the trailing edge region, still within the scope of an iterative potential flow, boundary layer program, appears feasible.
    Keywords: AERODYNAMICS
    Type: NASA-CR-158480
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  • 136
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    Rotary-wing aerodynamics. Volume 2: Performance prediction of helicopters (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Application of theories, as well as, special methods of procedures applicable to performance prediction are illustrated first, on an example of the conventional helicopter and then, winged and tandem configurations. Performance prediction of conventional helicopters in hover and vertical ascent are investigated. Various approaches to performance prediction in forward translation are presented. Performance problems are discussed only this time, a wing is added to the baseline configuration, and both aircraft are compared with respect to their performance. This comparison is extended to a tandem. Appendices on methods for estimating performance guarantees and growth of aircraft concludes this volume.
    Keywords: AERODYNAMICS
    Type: NASA-CR-3083
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  • 137
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    Stability and control characteristics of a monoplanar elliptic missile model at Mach numbers from 1.60 to 2.86 (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: An investigation was conducted of a monoplanar maneuverable missile concept having a nose forebody with a circular cross section and a centerbody and afterbody with elliptical cross sections. The tests involved several component changes and were conducted in the low Mach number test section of the Langley Unitary Plan wind tunnel at Mach numbers of 1.60, 2.16, and 2.86, at angles of attack ranging from -4 degs to 28 degs and at sideslip angles ranging from -4 degs to 8 degs. The most significant result was that at the highest Mach number (2.86), the configuration with the infrared nose produced nearly twice the axial force as the same configuration with the radar nose. The cranked wing had a destabilizing effect on the longitudinal stability and had no effect on the lateral-directional stability. The nose strakes had no effect longitudinally and were detrimental to the lateral-directional stability.
    Keywords: AERODYNAMICS
    Type: NASA-TP-1352 , L-12268
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  • 138
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    Supercritical flow about a thick circular-arc airfoil (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The supercritical flow about a biconvex circular-arc airfoil is being thoroughly documented at Ames Research Center in order to provide experimental test cases suitable for guiding and evaluating current and future computer codes. The effects of angle of attack, effects of leading and trailing-edge splitter plates, additional unsteady pressure fluctuation (buffeting) measurements and glow-field shadowgraphs, and application of an oil-film technique to display separated-wake streamlines were studied. Computed and measured pressure distributions for steady and unsteady flows, using a recent computer code representative of current methodology, are compared. It was found that the numerical solutions are often fundamentally incorrect in that only strong (shock-polar terminology) shocks are captured, whereas experimentally, both strong and weak shock waves appear.
    Keywords: AERODYNAMICS
    Type: NASA-TM-78549 , A-7693
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  • 139
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    Sonic-boom minimization with nose-bluntness relaxation (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A procedure which provides sonic-boom-minimizing equivalent area distributions for supersonic cruise conditions is described. This work extends previous analyses to permit relaxation of the extreme bluntness required by conventional low-boom shapes and includes propagation in a real atmosphere. The procedure provides area distributions which minimize either shock strength or overpressure.
    Keywords: AERODYNAMICS
    Type: NASA-TP-1348 , L-12464
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  • 140
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    A review of at rest droplet growth equations for condensing nitrogen in transonic cryogenic wind tunnels (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Droplet growth equations are reviewed in the free-molecular, transition, and continuum flow regimes with the assumption that the droplets are at rest with respect to the vapor. As comparison calculations showed, it was important to use a growth equation designed for the flow regime of interest. Otherwise, a serious over-prediction of droplet growth may result. The growth equation by Gyarmathy appeared to be applicable throughout the flow regimes and involved no iteration. His expression also avoided the uncertainty associated with selecting a mass accommodation coefficient and consequently involved less uncertainty in specifying adjustable parameters than many of the other growth equations.
    Keywords: AERODYNAMICS
    Type: NASA-TM-78821
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  • 141
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    Theoretical study of VTOL tilt-nacelle axisymmetric inlet geometries (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A systematic theoretical study of VTOL tilt-nacelle inlet design parameters is reported. The parameters considered are internal-lip contraction ratio, internal-lip major-to-minor axis ratio, diffuser-exit-area to throat-area ratio, maximum diffuser wall angle and shape. Each of the inlets was analyzed at the same given flow condition of free-stream velocity, angle between the free stream and centerline of the inlet, and diffuser-exit Mach number. The effects of these geometric parameters on surface static-pressure distribution, peak surface Mach number, diffusion velocity ratio, and tendency for the inlet flow to separate are presented.
    Keywords: AERODYNAMICS
    Type: NASA-TP-1380 , E-9756
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  • 142
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    Aerodynamic characteristics of a supersonic cruise airplane configuration at Mach numbers of 2.30, 2.96, and 3.30 (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: An investigation was made in the Langley Unitary Plan wind tunnel at Mach numbers of 2.30, 2.96, and 3.30 to determine the static longitudinal and lateral aerodynamic characteristics of a model of a supersonic cruise airplane. The configuration, with a design Mach number of 3.0, has a highly swept arrow wing with tip panels of lesser sweep, a fuselage chine, outboard vertical tails, and outboard engines mounted in nacelles beneath the wings. For wind tunnel test conditions, a trimmed value above 6.0 of the maximum lift-drag ratio was obtained at the design Mach number. The configuration was statically stable, both longitudinally and laterally. Data are presented for variations of vertical-tail roll-out and toe-in and for various combinations of components. Some roll control data are shown as are data for the various sand grit sizes used in fixing the boundary layer transition location.
    Keywords: AERODYNAMICS
    Type: NASA-TM-78792 , L-12570
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  • 143
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    Effects of upper surface modification on the aerodynamic characteristics of the NACA 63 sub 2-215 airfoil section (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: An upper surface modification designed to increase the maximum lift coefficient of a 63 sub 2 - 215 airfoil section was tested at Mach numbers of 0.2, 0.3, and 0.4 Reynolds numbers of 1.3 x 1 million, 2 x 10 sub 6 and 2.5 x 1 million. Comparisons of the aerodynamic coefficients before and after the modification were made. The upper surface modification increased the maximum lift coefficient of the airfoil significantly at all conditions.
    Keywords: AERODYNAMICS
    Type: NASA-TM-78503 , A-7507
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  • 144
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    Theoretical evaluation of high-speed aerodynamics for arrow-wing configurations (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The use of the theoretical methods to calculate the high-speed aerodynamic characteristics of arrow-wing supersonic cruise configurations was studied. Included are correlations of theoretical predictions with wind-tunnel data at Mach numbers from 0.8 to 2.7, examples of the use of theoretical methods to extrapolate the wind-tunnel data to full-scale flight condition, and presentation of a typical supersonic data package for an advanced supersonic transport application. A brief description of the methods and their application is given.
    Keywords: AERODYNAMICS
    Type: NASA-TP-1358 , L-12485
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  • 145
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    Numerical solution of transonic full stream function equations in conservation form (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The stream function equation in conservation form is solved iteratively based on the artificial compressibility method. The density is not a unique function of the mass flux. In order to avoid the ambiguity near the sonic line, the density is updated in terms of the velocity, which is obtained through a simple integration of a first order equation step by step in the flow field. Iteration algorithms and finite difference approximations are discussed and numerical results of both conservative and nonconservative calculations are presented.
    Keywords: AERODYNAMICS
    Type: NASA-CR-166200 , REPT-178
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  • 146
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    Ground effects on USB configurations (1979)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: Recent investigations of ground effects on aerodynamic characteristics have been stimulated by the interest in powered-lift STOL airplanes. The ground effects on upper-surface-blowing (USB) configurations may involve change in both the circulation forces and the jet reaction forces. In this note, a theoretical method is proposed for predicting these effects. It is shown that the predicted results agree well with available experimental data. In particular, the wing-alone method is shown to be incapable of predicting the ground effects of USB configurations.
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft; 16; Jan. 197
    Format: text
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  • 147
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    Lifting-line theory of oblique wings in transonic flows (1979)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: Three-dimensional corrections to the nonlinear mixed flow admitted by a high-aspect-ratio swept wing of practical interest are analyzed by solving a perturbation problem and matching its solution to that of an outer flow. The latter is identified with a linear solution involving a lifting line, but the centerline of the planform is not required to be straight and unyawed. The existence of a similarity in the three-dimensional flow structure for a certain oblique-wing geometry is demonstrated, along with a solution to the reduced problem in a high-subcritical case.
    Keywords: AERODYNAMICS
    Type: AD-A070406 , AIAA Journal; 17; Jan. 197
    Format: text
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  • 148
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    An experimental and theoretical investigation of the effect of nonmetric over-the-wing nacelles on wing-body aerodynamics (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Drag reduction benefits due to blowing the jet exhausts over the wing for a transport-type wing-body configuration were investigated in the Langley 16-foot transonic tunnel. A combination of a wing-body model and a powered-nacelle test rig was tested at Mach numbers of 0.50 and 0.80 at angles of attack from -2 degrees to 4 degrees and jet total-pressure ratios from jet off to 3 or 4 (depending on Mach number) for a variety of nacelle locations relative to the wing. The experimental results were compared with the predictions obtained from several theoretical techniques. It was concluded that positioning of the nacelles (nonmetric) can have large effects on the wing-body drag. Some positions yielded higher drag than the baseline position, whereas others yielded lower drag than the baseline position. The theoretical method which utilized a quasi-vortex-lattice for the wing and wing-jet interaction in combination with a jet entrainment model gave generally reasonable predictions of the drag increments.
    Keywords: AERODYNAMICS
    Type: NASA-TP-1503 , L-13010
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  • 149
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    Surface pressure data on a series of analytic forebodies at Mach numbers from 1.70 to 4.50 and combined angles of attack and sideslip (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Tabulated surface pressure data for a series of four forebodies which have analytically defined cross sections and which are based on a parabolic arc profile having a 20 deg half angle at the nose are presented without analysis. The first forebody has a circular cross section, and the second has a cross section which is an ellipse with an axis ratio of 2/1. The third has a cross section defined by a lobed analytic curve. The fourth forebody has cross sections which develop smoothly from circular at the pointed nose through the lobed analytic curve and back to circular at the aft end. The data generally cover angles of attack from -5 deg to 20 deg at angles of sideslip from 0 deg to 5 deg for Mach numbers of 1.70, 2.50, 3.95, and 4.50 at a constant Reynolds number.
    Keywords: AERODYNAMICS
    Type: NASA-TM-80062 , L-12780
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  • 150
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    A computer program for detailed analysis of the takeoff and approach performance capabilities of transport category aircraft (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The takeoff and approach performance of an aircraft is calculated in accordance with the airworthiness standards of the Federal Aviation Regulations. The aircraft and flight constraints are represented in sufficient detail to permit realistic sensitivity studies in terms of either configuration modifications or changes in operational procedures. The program may be used to investigate advanced operational procedures for noise alleviation such as programmed throttle and flap controls. Extensive profile time history data are generated and are placed on an interface file which can be input directly to the NASA aircraft noise prediction program (ANOPP).
    Keywords: AERODYNAMICS
    Type: NASA-TM-80120
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  • 151
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    Space shuttle orbiter trimmed center-of-gravity extension study. Volume 5: Effects of configuration modifications on the aerodynamic characteristics of the 140A/B orbiter at Mach numbers of 2.5, 3.95 and 4.6 (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Supersonic aerodynamic characteristics are presented for the 140A/B space shuttle orbiter configuration (0.010 scale) and for the configuration modified to incorporate geometry changes in the wing planform fillet region. The modifications designed to extend the orbiter's longitudinal trim capability to more forward center-of-gravity locations, included reshaping of the baseline wing planform fillet and adding canards. The investigation was made in the high Mach number test section of the Langley Unitary Plan Wind Tunnel at a Reynolds number of approximately 2.2 million based on fuselage reference length. The angle-of-attack range for the investigation extended from -1 deg to 31 deg. Data were obtained with the elevators and body flap deflected at appropriate negative and positive conditions to assess the trim limits.
    Keywords: AERODYNAMICS
    Type: NASA-TM-72661-VOL-5
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  • 152
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    Sensitivity study for a remotely piloted microwave-powered sailplane used as a high-altitude observation (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The sensitivity of several performance characteristics of a proposed design for a microwave-powered, remotely piloted, high-altitude sailplane to changes in independently varied design parameters was investigated. Results were expressed as variations from baseline values of range, final climb altitude and onboard storage of radiated energy. Calculated range decreased with increases in either gross weight or parasite drag coefficient; it also decreased with decreases in lift coefficient, propeller efficiency, or microwave beam density. The sensitivity trends for range and final climb altitude were very similar. The sensitivity trends for stored energy were reversed from those for range, except for decreasing microwave beam density. Some study results for single parameter variations were combined to estimate the effect of the simultaneous variation of several parameters: for two parameters, this appeared to give reasonably accurate results.
    Keywords: AERODYNAMICS
    Type: NASA-CR-159089
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  • 153
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    Pressure distributions on three different cruciform aft-tail control surfaces of a wingless missile at mach 1.60, 2.36, and 3.70 Volume 1: Trapezoidal tail (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The results of pressure distribution tests conducted in the Langley Unitary Plan wind tunnel are presented. The data were obtained for three sets of cruciform aft-tail control surfaces on a wingless missile model at Mach numbers of 1.60, 2.36, and 3.70 for angles of attack from -4 degrees to 20 degrees, model roll angles from 0 degrees to 90 degrees, and tail deflections of 0 degrees and 15 degrees. The test Reynolds number used was 6.6 million per meter.
    Keywords: AERODYNAMICS
    Type: NASA-TM-80097-VOL-1 , L-12993
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  • 154
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    Influence of optimized leading-edge deflection and geometric anhedral on the low-speed aerodynamic characteristics of a low-aspect-ratio highly swept arrow-wing configuration (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: An investigation conducted in the Langley 7 by 10 foot tunnel to determine the influence of an optimized leading-edge deflection on the low speed aerodynamic performance of a configuration with a low aspect ratio, highly swept wing. The sensitivity of the lateral stability derivative to geometric anhedral was also studied. The optimized leading edge deflection was developed by aligning the leading edge with the incoming flow along the entire span. Owing to spanwise variation of unwash, the resulting optimized leading edge was a smooth, continuously warped surface for which the deflection varied from 16 deg at the side of body to 50 deg at the wing tip. For the particular configuration studied, levels of leading-edge suction on the order of 90 percent were achieved. The results of tests conducted to determine the sensitivity of the lateral stability derivative to geometric anhedral indicate values which are in reasonable agreement with estimates provided by simple vortex-lattice theories.
    Keywords: AERODYNAMICS
    Type: NASA-TM-80083
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  • 155
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    The development of methods for predicting and measuring distribution patterns of aerial sprays (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The capability of conducting scale model experiments which involve the ejection of small particles into the wake of an aircraft close to the ground is developed. A set of relationships used to scale small-sized dispersion studies to full-size results are experimentally verified and, with some qualifications, basic deposition patterns are presented. In the process of validating these scaling laws, the basic experimental techniques used in conducting such studies, both with and without an operational propeller, were developed. The procedures that evolved are outlined. The envelope of test conditions that can be accommodated in the Langley Vortex Research Facility, which were developed theoretically, are verified using a series of vortex trajectory experiments that help to define the limitations due to wall interference effects for models of different sizes.
    Keywords: AERODYNAMICS
    Type: NASA-CR-158787 , ARL-79-1
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  • 156
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    Numerical optimization techniques for bound circulation distribution for minimum induced drag of nonplanar wings: Basic formulations (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A theoretical method was developed for determining the optimum span load distribution for minimum induced drag for subsonic nonplanar configurations. The undistorted wing wake is assumed to have piecewise linear variation of shed vortex sheet strength, resulting in a quadratic variation of bound circulation and span load. The optimum loading is obtained either through a direct technique, whereby derivatives of the drag expression are calculated analytically in terms of the unknown wake vortex sheet strengths. Both techniques agree well with each other and with available exact solutions for minimum induced drag.
    Keywords: AERODYNAMICS
    Type: NASA-CR-3154
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  • 157
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    Minimization theory of induced drag subject to constraint conditions (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Exact analytical solutions in terms of induced drag influence coefficients can be attained which define the spanwise loading with minimized induced drag, subject to specified constraint conditions, for any nonplanar wing shape or number of lift plus wing bending moment about a given wing span station. Example applications of the theory are made to a biplane, a wing in ground effect, a cruciform wing, a V-wing, a planar-wing winglet, and linked wingtips in formation flying. For minimal induced drag, the spanwise loading, relative to elliptic, is outboard for the biplane and is inboard for the wing in ground effect and for the planar-wing winglet. A spinoff of the triplane solution provides mathematically exact equations for downwash and sidewash about a planar vorticity sheet having an arbitrary loading distribution.
    Keywords: AERODYNAMICS
    Type: NASA-CR-3140
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  • 158
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    Investigation of aerodynamic characteristics of subsonic wings (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: An analytical strake design procedure is investigated. A numerical solution to the governing strake design equation is used to generate a series of strakes which are tested in a water tunnel to study their vortex breakdown characteristics. The strakes are scaled for use on a half-scale model of the NASA-LaRC general research fuselage with a 44 degrees trapezoidal wing. An analytical solution to the governing design equation is obtained. The strake design procedure relates the potential-flow leading-edge suction and pressure distributions to vortex stability. Several suction distributions are studied and those which are more triangular and peak near the tip generate strakes that reach higher angles of attack before vortex breakdown occurs at the wing trailing edge. For the same suction distribution, a conical rather than three dimensional pressure specification results in a better strake shape as judged from its vortex breakdown characteristics.
    Keywords: AERODYNAMICS
    Type: NASA-CR-158661
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  • 159
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    An Experimental Investigation of Forced Mixing of a Turbulent Boundary Layer in an Annular Diffuser (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The forced mixing process of a turbulent boundary layer in an axisymmetric annular diffuser using conventional wing-like vortex generators was studied. Flow field measurements were made at four axial locations downstream of the vortex generators. At each axial location, a total of 25 equally spaced profiles were measured behind three consecutive vortex generators which formed two pairs of vortex generators. Hot film anemometry probes measured the boundary layer turbulence structure at the same locations where pressure measurements were made. Both single and cross film probes were used. The diffuser turbulence data was teken only for a nominal inlet Mach number of 0.3. Three vortex generator configurations were tested. The differences between configurations involved changes in size and relative vortex generator positions. All three vortex generator configurations tested provided increases in diffuser performance. Distinct differences in the boundary layer integral properties and skin friction levels were noted between configurations. The axial turbulence intensity and Reynolds stress profiles measured displayed similarities in trends but differences in levels for the three configurations.
    Keywords: AERODYNAMICS
    Type: NASA-TM-79171 , E-9947
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  • 160
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    An implicit algorithm for the conservative, transonic full-potential equation with effective rotated differencing (1979)
    In:  CASI
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    Publication Date: 2019-06-27
    Description: A new differencing scheme for the conservative full potential equation which effectively simulates rotated differencing is presented. The scheme was implemented by an appropriate upwind bias of the density coefficient along coordinate directions. A fast, fully implicit, approximate factorization iteration scheme was then used to solve the resulting difference equations. Solutions for a number of traditionally difficult transonic airfoil test cases are presented.
    Keywords: AERODYNAMICS
    Type: NASA-TM-78570
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  • 161
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    Interaction between a normal shock wave and a turbulent boundary layer at high transonic speeds. Part 2: Wall shear stress (1979)
    In:  CASI
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    Publication Date: 2019-06-27
    Description: An analysis is presented of the flow in the two inner layers, the Reynolds stress sublayer and the wall layer. Included is the calculation of the shear stress at the wall in the interaction region. The limit processes considered are those used for an inviscid flow.
    Keywords: AERODYNAMICS
    Type: NASA-CR-158542
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  • 162
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    Surface pressure data for a supersonic-cruise airplane configuration at Mach numbers of 2.30, 2.96, 3.30 (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The tabulated results of surface pressure tests conducted on the wing and fuselage of an airplane model in the Langley Unitary Plan wind tunnel are presented without analysis. The model tested was that of a supersonic-cruise airplane with a highly swept arrow-wing planform, two engine nacelles mounted beneath the wing, and outboard vertical tails. Data were obtained at Mach numbers of 2.30, 2.96, and 3.30 for angles of attack from -4 deg to 12 deg. The Reynolds number for these tests was 6,560,000 per meter.
    Keywords: AERODYNAMICS
    Type: NASA-TM-80061 , L-12777
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  • 163
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    Observations on streamwise vortices in laminar and turbulent boundary layers (1979)
    In:  CASI
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    Publication Date: 2019-06-27
    Description: The frequent but often unsuspected presence of streamwise vortices in nominally two dimensional laminar and turbulent boundary layers and some of their consequences are described. Since there is no body of systematic information on streamwise vortices imbedded in boundary layers, a number of issues concerning their occurrence and behavior are discussed in the form of a set of succinct observations. Desirable experimental and numerical research to remedy the current lack of knowledge is recommended.
    Keywords: AERODYNAMICS
    Type: NASA-CR-159061
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  • 164
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    Reduction of computer usage costs in predicting unsteady aerodynamic loadings caused by control surface motions: Computer program description (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A digital computer program was developed to calculate unsteady loadings caused by motions of lifting surfaces with leading edge and trailing edge controls based on the subsonic kernel function approach. The pressure singularities at hinge line and side edges were extracted analytically as a preliminary step to solving the integral equation of collocation. The program calculates generalized aerodynamic forces for user supplied deflection modes. Optional intermediate output includes pressure at an array of points, and sectional generalized forces. From one to six controls on the half span can be accomodated.
    Keywords: AERODYNAMICS
    Type: NASA-CR-145354 , NAS 1.26:145354
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  • 165
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    Computer programs for calculating pressure distributions including vortex effects on supersonic monoplane or cruciform wing-body-tail combinations with round or elliptical bodies (1979)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Computer programs are presented which are capable of calculating detailed aerodynamic loadings and pressure distributions acting on pitched and rolled supersonic missile configurations which utilize bodies of circular or elliptical cross sections. The applicable range of angle of attack is up to 20 deg, and the Mach number range is 1.3 to about 2.5. Effects of body and fin vortices are included in the methods, as well as arbitrary deflections of canard or fin panels.
    Keywords: AERODYNAMICS
    Type: NASA-CR-3122 , NEAR-TR-154
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  • 166
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    Flow measurements in a turbine scroll (1979)
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    Publication Date: 2019-07-13
    Description: The paper presents a study conducted to determine experimentally the flow behavior in the combined scroll nozzle assembly of a radial inflow turbine. It is shown that hot film anemometry was used to measure the flow velocity in the scroll.
    Keywords: AERODYNAMICS
    Type: Flow in primary, non-rotating passages in turbomachines; Dec 02, 1979 - Dec 07, 1979; New York, NY
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  • 167
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    Investigation of a reattaching turbulent shear layer Flow over a backward-facing step (1979)
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    Publication Date: 2019-07-13
    Description: The paper studies incompressible flow over a backward-facing step in order to investigate the flow characteristics in the separated shear layer, the reattachment zone, and the redeveloping boundary layer after reattachment. It is shown that turbulent intensities and shear stress reach maxima in the reattachment zone, followed by rapid decay near the surface after reattachment. In addition, it is found that downstream of reattachment, the flow returns very slowly to the structure of an ordinary turbulent boundary layer.
    Keywords: AERODYNAMICS
    Type: Flow in primary, non-rotating passages in turbomachines; Dec 02, 1979 - Dec 07, 1979; New York, NY
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  • 168
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    A two dimensional model of viscous slot flow (1979)
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    Publication Date: 2019-07-13
    Description: The effects of viscosity on flows through slots are investigated. Using Briley's formulation of the Alternating Direction Implicit method together with the Thompson transformation, numerical solution of viscous incompressible flow through a slot is simulated, for Reynolds number 1000 and openness ratio one tenth. The problem is formulated in terms of stream function and vorticity. A wall iteration of Israeli type is employed to iteratively induce the no slip condition on velocity.
    Keywords: AERODYNAMICS
    Type: Advances in computer methods for partial differential equations - III; Jun 20, 1979 - Jun 22, 1979; Bethlehem, PA
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  • 169
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    Periodic steamwise variations of heat transfer coefficients for incline and staggered arrays of circular jets with crossflow of spent air (1979)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: Heat transfer characteristics were measured for inline and staggered arrays of circular jets impinging on a surface parallel to the jet orifice plate. The impinging flow was constrained to exit in a single direction along the channel formed by the jet plate and the heat transfer surface. In this configuration the air discharged from upstream transverse rows of jet holes imposes a crossflow of increasing magnitude on the succeeding downstream jet rows. Streamwise heat transfer coefficient profiles were determined for a streamwise resolution of one-third the streamwise hole spacing, utilizing a specially constructed test surface.
    Keywords: AERODYNAMICS
    Type: ASME PAPER 79-WA/GT-11 , Winter Annual Meeting; Dec 02, 1979 - Dec 07, 1979; New York, NY
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  • 170
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    Torque requirement of rotating rods in airflow (1979)
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    Publication Date: 2019-07-13
    Description: Experiments were performed to determine the torque required for rotating a rotor disk fitted with a number of radially arranged rods placed into a ducted airflow. An array of stationary rods, also radially arranged, was placed upstream close to the rotor with a small gap between the rods to cause wake interference. The results show that torque generally increased with airflow and the rate of increase varied considerably. At lower values of airflow, the rate of increase was larger than at higher airflow, and definite torque peaks occurred at certain airflow rates, where the torque attained a maximum within the test airflow range. During the test, a maximum blade passage frequency of 2037 Hz was attained. The results also show that the torque peaks occurred at the same Strouhal number for all speeds.
    Keywords: AERODYNAMICS
    Type: ASME PAPER 79-WA/FE-23 , Winter Annual Meeting; Dec 02, 1979 - Dec 07, 1979; New York, NY
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  • 171
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    Advanced technology airfoil research, volume 2 (1979)
    In:  CASI
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    Publication Date: 2019-07-13
    Description: A comprehensive review of airfoil research is presented. The major thrust of the research is in three areas: development of computational aerodynamic codes for airfoil analysis and design, development of experimental facilities and test techniques, and all types of airfoil applications.
    Keywords: AERODYNAMICS
    Type: NASA-CP-2046 , L-12232 , Mar 07, 1978 - Mar 09, 1978; Langley Research Center, Hampton, VA; United States
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  • 172
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    Computation of turbulent near wake for asymmetric airfoils (1979)
    In:  CASI
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    Publication Date: 2019-07-13
    Description: A numerical procedure for studying the turbulent near wake of two dimensional airfoil sections is presented. The Reynolds Navier-Stokes equations were written for flow about bodies of arbitrary geometry and solved on an arbitrary nonuniform curvilinear computational mesh. Eddy viscosity and Reynolds stress turbulence transport models are considered. Specific examples are shown for airfoil section by using an algebraic viscosity model with streamwise relaxation and the interactive Reynolds stress model.
    Keywords: AERODYNAMICS
    Type: NASA-TM-78581 , A-7803 , DEA meeting on Viscous and Interacting Flow Field Effects; Apr 24, 1979 - Apr 26, 1979; Meersburg/Bodensee; Germany
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  • 173
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    Experimental studies on the effects of a sting support on the pressure distribution around a spherical object (1979)
    In:  CASI
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    Publication Date: 2019-07-13
    Description: Experiments were conducted on a spherical object, 2.5 inches in diameter, to obtain the pressure distribution around its meridan plane. In most of the tests the sphere was provided with a tail consisting of a circular cylinder that was attached directly to the rear with its axis in alignment with the center of the sphere. In some tests the tail was removed and the sphere alone was tested for comparison purposes. The main object of the tests was to obtain information on tail interference with the pressure distribution. The results of the tests show that the pressure distribution was affected by the presence of the tail to a minor extent only, while major differences occurred with the variation of the Reynolds number. The experiments were performed both in an open as well as inside a closed wind tunnel under steady flow conditions at Reynolds numbers ranging from 0.91 to 2.6 x 100000.
    Keywords: AERODYNAMICS
    Type: NASA-CR-158127
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  • 174
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    Effect of lip and centerbody geometry on aerodynamic performance of inlets for tilting-nacelle VTOL aircraft (1979)
    In:  CASI
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    Publication Date: 2019-07-13
    Description: Inlets for tilt-nacelle VTOL aircraft must operate over a wide range of incidence angles and engine weight flows without internal flow separation. Wind tunnel tests of scale model inlets were conducted to evaluate the effectiveness of three geometric variables to provide this capability. Increasing the lip contraction ratio increased the separation angle at all engine weight flows. The optimum axial location of the centerbody occurred when its leading edge was located just downstream of the inlet lip. Compared with a short centerbody, the optimum location of the centerbody resulted in an increase in separation angle at all engine weight flows. Decreasing the lip major-to-minor-axis ratio increased the separation angle at the lower engine weight flows.
    Keywords: AERODYNAMICS
    Type: NASA-TM-79056 , E-9866 , AIAA PAPER 79-0381 , Aerospace Sci. Meeting; Jan 15, 1979 - Jan 17, 1979; New Orleans, LA; United States
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  • 175
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    Aerodynamic performance of scarf inlets (1979)
    In:  CASI
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    Publication Date: 2019-07-13
    Description: A scarf inlet is characterized by having a longer lower lip than upper lip leading to both aerodynamic and acoustic advantages. Aerodynamically, a scarf inlet has higher angle of attack capability and is less likely to ingest foreign objects while the aircraft is on the ground. Acoustically, a scarf inlet provides for reduced inlet radiated noise levels below the engine as a result of upward reflection and refraction of inlet radiated noise. Results of a wind tunnel test program are presented which illustrate the aerodynamic performance of two different scarf inlet designs. Based on these results, scarf inlet performance is summarized in a way to illustrate the advantages and limitations of a scarf inlet compared to an axisymmetric inlet.
    Keywords: AERODYNAMICS
    Type: NASA-TM-79055 , E-9865 , Aerospace Sci. Meeting; Jan 15, 1979 - Jan 17, 1979; New Orleans, LA; United States
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  • 176
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    A numerical solution algorithm for prediction of turbulent aerodynamic corner flows (1979)
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    Publication Date: 2019-07-13
    Description: A numerical solution algorithm is established for prediction of subsonic turbulent three-dimensional flows in aerodynamic configuration juncture regions. In concert with a complete three-dimensional exterior potential flow solution, the developed parabolic algorithm yields prediction of the details of the corner region flowfield. Turbulence closure is established using the complete Reynolds stress. Pressure coupling is accomplished using the concepts of complementary and particular solutions to a Poisson equation. Numerical results for three-dimensional turbulent flow in the juncture of two intersecting parabolic arc airfoils are presented.
    Keywords: AERODYNAMICS
    Type: AIAA PAPER 79-0073 , American Institute of Aeronautics and Astronautics, Aerospace Sciences Meeting; Jan 15, 1979 - Jan 17, 1979; New Orleans, LA
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  • 177
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    Computational aerodynamics development and outlook /Dryden Lecture in Research for 1979/ (1979)
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    Publication Date: 2019-07-13
    Description: Some past developments and current examples of computational aerodynamics are briefly reviewed. An assessment is made of the requirements on future computer memory and speed imposed by advanced numerical simulations, giving emphasis to the Reynolds averaged Navier-Stokes equations and to turbulent eddy simulations. Experimental scales of turbulence structure are used to determine the mesh spacings required to adequately resolve turbulent energy and shear. Assessment also is made of the changing market environment for developing future large computers, and of the projections of micro-electronics memory and logic technology that affect future computer capability. From the two assessments, estimates are formed of the future time scale in which various advanced types of aerodynamic flow simulations could become feasible. Areas of research judged especially relevant to future developments are noted.
    Keywords: AERODYNAMICS
    Type: AIAA PAPER 79-0129 , American Institute of Aeronautics and Astronautics, Aerospace Sciences Meeting; Jan 15, 1979 - Jan 17, 1979; New Orleans, LA
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  • 178
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    Aerodynamic performance of scarf inlets (1979)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: A scarf inlet is characterized by having a longer lower lip than upper lip leading to both aerodynamic and acoustic advantages. Aerodynamically, a scarf inlet has higher angle of attack capability and is less likely to ingest foreign objects while the aircraft is on the ground. Acoustically, a scarf inlet provides for reduced inlet radiated noise levels below the engine as a result of upward reflection and refraction of inlet radiated noise. Results of a wind tunnel test program are presented which illustrate the aerodynamic performance of two different scarf inlet designs. Based on these results, scarf inlet performance is summarized in a way to illustrate the advantages and limitations of a scarf inlet compared to an axisymmetric inlet.
    Keywords: AERODYNAMICS
    Type: AIAA PAPER 79-0380 , American Institute of Aeronautics and Astronautics, Aerospace Sciences Meeting; Jan 15, 1979 - Jan 17, 1979; New Orleans, LA
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  • 179
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    Simulation of three-dimensional compressible viscous flow on the Illiac IV computer (1979)
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    Publication Date: 2019-07-13
    Description: Complicated three-dimensional viscous transonic flows about bodies at high angles of attack are solved on the Illiac IV computer. It is shown that certain approximate forms of the compressible Reynolds-averaged Navier-Stokes equations can be computed about realistic three-dimensional geometries with relative ease on the Illiac IV. The ease and efficiency with which this can be done depend on the approximations made in the basic equations, the choice of the numerical algorithm used for the solution, and the data-base system that controls the data management and identifies and manipulates the vectors. A pencil data-base system is found to be particularly suitable for the approximations and numerical method chosen to produce the results presented. In addition, some comparisons are made of computer predictions with experimental results for various lows about hemisphere-cylinders in both subsonic and supersonic free streams. The same viscous model and numerical model are used, showing good qualitative agreement in the location of separation lines and pressure distributions.
    Keywords: AERODYNAMICS
    Type: AIAA PAPER 79-0206 , American Institute of Aeronautics and Astronautics, Aerospace Sciences Meeting; Jan 15, 1979 - Jan 17, 1979; New Orleans, LA
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  • 180
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    Supersonic aerodynamic trade data for a low-profile monoplanar missile concept (1979)
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    Publication Date: 2019-07-13
    Description: A monoplanar missile concept has been studied which shows promise of improving the aerodynamic performance of air-launched missiles. This missile concept has a constant eccentricity elliptical cross-section body. Since current guidance and propulsion technologies influence missile nose and base shapes, an experimental investigation has been conducted at Mach number 2.50 to determine the effects of variations in these shapes on the missile aerodynamics. Results of these tests are presented.
    Keywords: AERODYNAMICS
    Type: AIAA PAPER 79-0222 , American Institute of Aeronautics and Astronautics, Aerospace Sciences Meeting; Jan 15, 1979 - Jan 17, 1979; New Orleans, LA
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  • 181
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    Unsteady thin airfoil theory for transonic flows with embedded shocks (1979)
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    Publication Date: 2019-07-13
    Description: Classical unsteady thin airfoil theory fails for low frequencies at the subsonic freestream Mach number, because of the formation of a shock wave that shields the forward region of the airfoil from aft generated disturbances. In the present paper, the classical thin airfoil theory is modified to account for the presence and induced motion of such shocks. The modification consists of taking the steady local Mach number to be a simple step discontinuity, normal to the undisturbed flow, separating two uniform regions. Predicted regions are shown to correlate well both with the experiment and finite difference calculations.
    Keywords: AERODYNAMICS
    Type: AIAA PAPER 79-0204 , American Institute of Aeronautics and Astronautics, Aerospace Sciences Meeting; Jan 15, 1979 - Jan 17, 1979; New Orleans, LA
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  • 182
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    Axisymmetric internal flows with shocks (1979)
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    Publication Date: 2019-07-13
    Description: Internal flow problems with supersonic entrance conditions and subsonic exit conditions are studied. The suitability of applying the transonic-small disturbance theory to internal flows is examined and found to be very limited. The full inviscid equations in nonconservative form are solved by relaxation. Jump conditions which conserve mass and normal momentum are applied explicitly at shock waves. This method is suitable for solving flows which include supersonic-subsonic shock waves nearly normal to the streamlines.
    Keywords: AERODYNAMICS
    Type: AIAA PAPER 79-0015 , American Institute of Aeronautics and Astronautics, Aerospace Sciences Meeting; Jan 15, 1979 - Jan 17, 1979; New Orleans, LA
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  • 183
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    Computation of three-dimensional turbulent separated flows at supersonic speeds (1979)
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    Publication Date: 2019-07-13
    Description: Numerical solutions of the time-averaged Navier-Stokes equations employing a simple eddy-viscosity model have been obtained for three dimensional turbulent flow fields at supersonic speeds. The computer results are compared with a series of experimental test flows describing the interaction of a swept shock wave with a turbulent boundary layer for various shock-wave strengths. Very good agreement is obtained between the computed and experimental surface and flow-field results. The computed flow fields are examined in detail to investigate the physics of this type of flow field. Questions concerning the existence of a vortex and the relationship between converging surface oil streaks and the resulting flow field are addressed.
    Keywords: AERODYNAMICS
    Type: AIAA PAPER 79-0002 , American Institute of Aeronautics and Astronautics, Aerospace Sciences Meeting; Jan 15, 1979 - Jan 17, 1979; New Orleans, LA
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  • 184
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    Numerical comparisons of panel methods at subsonic and supersonic speeds (1979)
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    Publication Date: 2019-07-13
    Description: Numerical comparisons between some recently developed surface panel methods and well-established methods are made to assess their accuracy at subsonic and supersonic speeds. The results at subsonic speeds indicate similar improvements for the methods investigated over the low order source method. At supersonic speeds, stable and accurate results were obtained with the surface panel methods. Significant differences between tangential mass flux and tangential velocity boundary conditions occurred, especially at low fineness ratios and higher Mach numbers. The advantages of the general source/doublet panel formulation at both subsonic and supersonic speeds are noted.
    Keywords: AERODYNAMICS
    Type: AIAA PAPER 79-0404 , American Institute of Aeronautics and Astronautics, Aerospace Sciences Meeting; Jan 15, 1979 - Jan 17, 1979; New Orleans, LA
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  • 185
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    Comparison of two flow surveys above stalled wings (1979)
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    Publication Date: 2019-07-13
    Description: A laser velocimeter (LV) surveyed the flow above two stalled wings. Each wing was tested in a different wind tunnel at different Mach numbers. The low-Mach-number test had an angle of attack of 19.4 deg, 0.15 Mach number, and 1 x 1,000,000 Reynolds number. The mean velocities above the reversed, separated flow were closely modeled by error function profiles. Thus, the flow resembled a turbulent free-shear layer. The high-Mach-number test had an angle of attack of 19.5 deg, 0.49 Mach number, and 1,400,000 Reynolds number. A series of strong, discrete vortices were shed from the airfoil crest at regular intervals. Both tests demonstrated the importance of the unsteady part of the velocities.
    Keywords: AERODYNAMICS
    Type: AIAA PAPER 79-0147 , American Institute of Aeronautics and Astronautics, Aerospace Sciences Meeting; Jan 15, 1979 - Jan 17, 1979; New Orleans, LA
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  • 186
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    Control of forebody three-dimensional flow separations (1979)
    In:  CASI
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    Publication Date: 2019-07-13
    Description: Some experiments involving the development of the turbulent symmetric vortex flow about the lee side of a 5 deg semiangle conical forebody at high relative incidence are discussed. The cone was immersed in a Mach 0.6 airstream at a Reynolds number of 13.5 million based on the 1.4 - m axial length of the cone. Novel means of controlling the degree of asymmetry using blowing very close to the nose were investigated. Small amounts of air injected normally or tangentially to the cone surface, but on one side of the leeward meridian and beneath the vortex farthest from the wall, were effective in biasing the asymmetry. With this reorientation of the forebody vortices, the amplitude of the side force could be reduced to the point where its direction was reversed. This phenomenon could be obtained either by changing the blowing rate at constant incidence or by changing incidence at constant blowing rate. Normal injection was more effective than tangential injection. An organized and stable flow structure emerged with the jet vortices positioned above the forebody vortices.
    Keywords: AERODYNAMICS
    Type: NASA-TM-78593 , A-7841 , AGARD Fluid Dyn. Panel Symp. on Aerodyn. Characteristics of Controls; May 01, 1979; Naples
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  • 187
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    Recent applications of theoretical analysis to V/STOL inlet design (1979)
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    Publication Date: 2019-07-13
    Description: A brief description of the axisymmetric potential flow and boundary layer analysis methods used at the NASA Lewis Research Center, is presented. Application of this method to inlet problems arising from both tilt-nacelle and fixed-nacelle V/STOL aircraft configurations is illustrated. A three-dimensional inlet analysis computer program is described and the preliminary results presented. Finally, a suggested approach to optimum design of inlets for high angle-of-attack operation is discussed.
    Keywords: AERODYNAMICS
    Type: U.S. Navy, Workshop on V/STOL Aerodynamics; May 16, 1979 - May 18, 1979; Monterey, CA
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  • 188
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    Effect of nozzle spacing on ground interference forces for a two jet V/STOL aircraft (1979)
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    Publication Date: 2019-07-13
    Description: The effect of nozzle spacing on ground interference forces was investigated for a two jet V/STOL aircraft design. The need for information on the effect of jet spacing arises because of the tradeoff between mechanical complexity, which calls for close spacing, and roll control moments, which call for wider spacing. The ground interference forces on a two jet V/STOL aircraft model were measured for a range of nozzle spacings. Interference forces showed a complicated behavior with nozzle spacing, fuselage geometry, and height above ground. For some conditions a slight change in nozzle spacing resulted in a fourfold change in the interference force from 3% to 12% of the basic jet thrust. An understanding of the observed aircraft force behavior was developed using detailed measurements of the upwash flow properties, along with force and pressure measurements on a series of two dimensional fuselage representations.
    Keywords: AERODYNAMICS
    Type: AIAA PAPER 79-1856 , American Institute of Aeronautics and Astronautics, Aircraft Systems and Technology Meeting; Aug 20, 1979 - Aug 22, 1979; New York, NY
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  • 189
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    Evaluation of methods for prediction of propulsion system drag (1979)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: The results of a study directed toward compilation of a theoretical and experimental data base covering inlet/airframe and nozzle/afterbody integration are described, with the major emphasis on the evaluation of the adequacy for preliminary design purposes of the data base for afterbody/propulsion system interference effects. Prediction methods that exist for afterbody/airframe interference effects are evaluated with respect to the requirements of breadth, ease of application and accuracy that are important for preliminary design.
    Keywords: AERODYNAMICS
    Type: AIAA PAPER 79-1148 , AIAA, SAE, and ASME, Joint Propulsion Conference; Jun 18, 1979 - Jun 20, 1979; Las Vegas, NV
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  • 190
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    Numerical analysis of turbulent wakes of axial flow turbomachinery rotor blades (1979)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: The wakes of rotor blades are turbulent, three-dimensional, and are subjected to curvature and rotation effects. The objective of this study is to predict the development of such wakes and compare the predictions with the existing data. A finite difference procedure is employed in the numerical analysis of the wake utilizing the continuity, momentum, and turbulence closure equations in the rotating curvilinear and non-orthogonal coordinate system. The turbulence closure is affected by the two equations model and the simplified Reynolds stress model. The predictions from both the models agree well with the mean velocity and the turbulence data.
    Keywords: AERODYNAMICS
    Type: Turbulent boundary layers: Forced, incompressible, non-reacting; Joint Applied Mechanics, Fluids Engineering and Bioengineering Conference; Jun 18, 1979 - Jun 20, 1979; Niagara Falls, NY
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  • 191
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    An elliptic representation of coupled boundary layers and inviscid core for computation of separated internal flows (1979)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: This report presents a viscous-inviscid calculation method for the prediction of turbulent incompressible flows in diffusers with small regions of stall. Integral turbulent boundary layer equations (BLE) are used to provide boundary conditions for a finite difference representation of the inviscid core. The BLE are applied at the floating displacement-thickness line, resulting in a simulataneous set of nonlinear block tridiagonal equations which are solved iteratively using a sucessive line-relaxation technique. Results of the method have been applied to calculate the performance of a variety of asymmetric stalled diffusers.
    Keywords: AERODYNAMICS
    Type: Turbulent boundary layers: Forced, incompressible, non-reacting; Joint Applied Mechanics, Fluids Engineering and Bioengineering Conference; Jun 18, 1979 - Jun 20, 1979; Niagara Falls, NY
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  • 192
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    Aerodynamic effects of an attitude control vane on a tilt-nacelle V/STOL propulsion system (1979)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: One possible technique for obtaining longitudinal control on a tilt-nacelle V/STOL aircraft is the use of a variable attitude vane assembly mounted in the propulsion system exhaust. Deflecting the vane produces large forces and moments without depending on forward speed of the aircraft. Tests are carried out in the Ames 40 by 80 ft wind tunnel on a large-scale tilt-nacelle V/STOL propulsion system with and without a variable attitude control vane assembly. Aerodynamic characteristics are analyzed in terms of nacelle aerodynamics, vane aerodynamics, and vane-induced effects on the nacelle aerodynamics. It is shown that the aerodynamic forces due to the nacelle without the vane can be a significant part of the total forces produced by the propulsion system. The control vane effectively produces large changes in pitching moment which are accompanied by significant changes in total lift and drag. The vane has a substantial effect on the propulsion-system aerodynamics. Other pertinent results are also given.
    Keywords: AERODYNAMICS
    Type: AIAA PAPER 79-1855 , American Institute of Aeronautics and Astronautics, Aircraft Systems and Technology Meeting; Aug 20, 1979 - Aug 22, 1979; New York, NY
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  • 193
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    Wing aerodynamic loading caused by jet-induced lift associated with STOL-OTW configurations (1979)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: Surface pressure distributions were obtained with model-scale STOL-OTW configurations using various nozzles designed to promote flow attachment to the wing-flap surface. The nozzle configurations included slot-types and both circular and slot nozzles with external flow deflectors. The wing aerodynamic loading caused by the jet-induced lift is presented in conventional terms of delta p/q as a function of chordwise surface distance in the nozzle centerline plane as well as outboard of the nozzle centerline. Included in the geometric variables affecting the wing loading are nozzle roof/deflector angle, chordwise location of the nozzle, wing size, and flap deflection angle.
    Keywords: AERODYNAMICS
    Type: AIAA PAPER 79-1664 , American Institute of Aeronautics and Astronautics, Atmospheric Flight Mechanics Conference; Aug 06, 1979 - Aug 08, 1979; Boulder, CO
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  • 194
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    Wind tunnel performance of four energy efficient propellers designed for Mach 0.8 cruise (1979)
    In:  CASI
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    Publication Date: 2019-07-13
    Description: Several advanced aerodynamic and acoustic concepts were investigated in recent wind tunnel tests performed in the NASA-Lewis Research Center 8x6 foot wind tunnel. These concepts included aerodynamically integrated propeller/nacelles, area-ruling, blade sweep, reduced blade thickness, and power (disk) loadings several times higher than conventional designs. Four eight-bladed propeller models were tested to determine aerodynamic performance. Relative noise measurements were made on three of the models at cruise conditions. Three of the models were designed with swept blades and one with straight blades. At the design Mach number of 0.8, power coefficient of 1.7, and advance ratio of 3.06, the straight bladed model had the lowest net efficiency of 75.8 percent. Increasing the sweep to 30 deg improved the performance to near 77 percent. Installation of an area-ruled spinner on a 30 deg sweep model further improved the efficiency to about 78 percent. The model with the highest blade sweep (45 deg) and an area-ruled spinner had the highest net efficiency of 78.7 percent, and at lower power loadings the efficiency exceeded 80 percent. At lower Mach numbers the 30 deg swept model had the highest efficiency. Values near 81 percent were obtained for the design loading at speeds to Mach 0.7. Relative noise measurements indicated that the acoustically designed 45 deg sweep model reduced the near field cruise noise by between 5 and 6 dB.
    Keywords: AERODYNAMICS
    Type: NASA-TM-79124 , E-9960 , Business Aircraft Meeting; Apr 03, 1979 - Apr 06, 1979; Wichita, KS; United States
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  • 195
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    Time history solution program, L225 (TEV126). Volume 2: Supplemental system design and maintenance document (1979)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The time history solution program L225 (TEV126) is described. The program calculates the time responses of a linear system by convoluting the impulsive response functions with the time dependent excitation. The convolution is performed as a multiplication in the frequency domain. Fast Fourier transform techniques are used to transform the product back into the time domain to obtain response time histories. The design and structure of the program is presented.
    Keywords: AERODYNAMICS
    Type: NASA-CR-2860 , D6-44469-VOL-2
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  • 196
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    A program for calculating load coefficient matrices utilizing the force summation method, L218 (LOADS). Volume 2: Supplemental system design and maintenance document (1979)
    In:  CASI
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    Publication Date: 2019-07-13
    Description: The LOADS computer program L218 which calculates dynamic load coefficient matrices utilizing the force summation method is described. The load equations are derived for a flight vehicle in straight and level flight and excited by gusts and/or control motions. In addition, sensor equations are calculated for use with an active control system. The load coefficient matrices are calculated for the following types of loads: (1) translational and rotational accelerations, velocities, and displacements; (2) panel aerodynamic forces; (3) net panel forces; and (4) shears, bending moments, and torsions.
    Keywords: AERODYNAMICS
    Type: NASA-CR-2854 , D6-44463-VOL-2
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  • 197
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    Equation modifying program, L219 (EQMOD). Volume 2: Supplemental system design and maintenance document (1979)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A digital computer program, L219 (EQMOD), available for execution on the CDC 6600 is described. The program modifies matrices according to card input instructions and prepares magnetic files of matrices suitable for use in the linear systems analysis program (QR) and the random harmonic analysis program L221 (TEV156). The particular field of application of the program is the modification of the theoretical equations of motion and load equations generated in DYLOFLEX by the equation of motion program (L217) and the load equation program (L218), respectively.
    Keywords: AERODYNAMICS
    Type: NASA-CR-2856 , D6-44465-VOL-2
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  • 198
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    High-performance wings with significant leading-edge thrust at supersonic speeds (1979)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: A new class of curved-leading-edge wings with which significant levels of leading-edge thrust may be achieved at moderate supersonic speeds is suggested. A recent analysis of the factors limiting such leading-edge thrust has led to a new method for the prediction of attainable leading-edge thrust from subsonic through supersonic speeds for wings of arbitrary planform. Recent supersonic tests of a new wing shape, which largely meets design criteria given by the new prediction method, give evidence of significant levels of leading-edge thrust. The consequent unusually high levels of aerodynamic performance should renew interest in supersonic-cruise vehicle design in general and in cruise-speed selection in particular.
    Keywords: AERODYNAMICS
    Type: AIAA PAPER 79-1871 , American Institute of Aeronautics and Astronautics, Aircraft Systems and Technology Meeting; Aug 20, 1979 - Aug 22, 1979; New York, NY
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  • 199
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    Performance of a V/STOL tilt nacelle inlet with blowing boundary layer control (1979)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: A scale model of a V/STOL tilt nacelle fitted to a 0.508 m single stage fan was tested in the NASA Lewis low speed wind tunnel to determine the effect of diffuser blowing on the inlet aerodynamics and aeromechanical performance. The test was conducted over a range of freestream speeds (up to 120 knots) and angles-of attack (up to 120 deg). In general, diffuser blowing had a beneficial affect on all performance parameters. The angle-of-attack range for a separation-free flow substantially increased, and the fan face distortion reduced with a corresponding increase in total pressure recovery. Discrete narrow band blade stress peaks which were common to the nonblowing (baseline) configuration were eradicated with diffuser blowing.
    Keywords: AERODYNAMICS
    Type: AIAA PAPER 79-1163 , AIAA, SAE, and ASME, Joint Propulsion Conference; Jun 18, 1979 - Jun 20, 1979; Las Vegas, NV
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  • 200
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    Effect of viscosity on wind-tunnel wall interference for airfoils at high lift (1979)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: The effect of the walls of a wind tunnel on the subsonic, two-dimensional flow past airfoils at high angles of attack is studied theoretically and experimentally. The computerized analysis, which is based on iteratively coupled potential-flow, boundary-layer, and separated-flow analyses, includes determining the effect of viscosity and flow separation on the airfoil/wall interaction. Predictions of the effects of wind-tunnel wall on the lift of airfoils are compared with wall corrections based on inviscid image analyses, and with experimental data. These comparisons are made for airfoils that are large relative to the size of the test section of the wind tunnel. It is shown that the inviscid image modeling of the wind-tunnel interaction becomes inaccurate at lift coefficients near maximum lift or when the airfoil/wall interaction is particularly strong. It is also shown that the present method of analysis (which includes boundary-layer and flow-separation effects) will provide accurate wind-tunnel wall corrections for lift coefficients up to maximum lift.
    Keywords: AERODYNAMICS
    Type: AIAA PAPER 79-1534 , American Institute of Aeronautics and Astronautics, Fluid and Plasma Dynamics Conference; Jul 23, 1979 - Jul 25, 1979; Williamsburg, VA
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