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  • AERODYNAMICS  (83)
  • COMMUNICATIONS AND RADAR  (49)
  • GENERAL
  • 1975-1979  (133)
  • 1977  (133)
  • 1
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    Vortex lattice prediction of subsonic aerodynamics of hypersonic vehicle concepts (1977)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The vortex lattice method introduced by Lamar and Gloss (1975) was applied to the prediction of subsonic aerodynamic characteristics of hypersonic body-wing configurations. The reliability of the method was assessed through comparison of the calculated and observed aerodynamic performances of two National Hypersonic Flight Research Facility craft at Mach 0.2. The investigation indicated that a vortex lattice model involving 120 or more panel elements can give good results for the lift and induced drag coefficients of the craft, as well as for the pitching moment at angles of attack below 10 to 15 deg. Automated processes for calculating the local slopes of mean-camber surfaces may also render the method suitable for use in preliminary design phases.
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft; 14; Oct. 197
    Format: text
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    NASA TECHNICAL REPORTS
  • 2
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    Minimum-weight codewords in the (128,64) BCH (1977)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: Techniques of combinational algebra and computer simulation are combined to determine the number of weight 22 codewords in the (128,64) BCH code which is being studied for use on future deep-space missions.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network p92-94 (SEE N78-24161 15-12)
    Format: text
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    NASA TECHNICAL REPORTS
  • 3
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    Application of laser velocimetry to aircraft wake-vortex measurements (1977)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The theory and use of a laser velocimeter that makes simultaneous measurements of vertical and longitudinal velocities while rapidly scanning a flow field laterally are described, and its direct application to trailing wake-vortex research is discussed. Pertinent measurements of aircraft wake-vortex velocity distributions obtained in a wind tunnel and water towing tank are presented. The utility of the velocimeter to quantitatively assess differences in wake velocity distributions due to wake dissipating devices and span loading changes on the wake-generating model is also demonstrated.
    Keywords: AERODYNAMICS
    Type: Wake Vortex Minimization; p 157-192
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 4
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    Aerodynamic characteristics at Mach numbers from 0.33 to 1.20 of a wing-body design concept for a hypersonic research airplane (1977)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: An experimental investigation of the static aerodynamic characteristics of a model of one design concept for the proposed National Hypersonic Flight Research Facility was conducted in the Langley 8 foot transonic pressure tunnel. The experiment consisted of configuration buildup from the basic body by adding a wing, center vertical tail, and a three module or six module scramjet engine. The freestream test Mach numbers were 0.33, 0.80, 0.90, 0.95, 0.98, 1.10, and 1.20 at Reynolds numbers per meter ranging from 4.8 x 1 million to 10.4 x 1 million. The test angle of attack range was approximately -4 deg to 22 deg at constant angles of sideslip of 0 deg and 4 deg; the angle of sideslip ranged from about -6 deg to 6 deg at constant angles of attack of 0 deg and 17 deg. The elevons were deflected 0 deg, -10 deg, and -20 deg with rudder deflections of 0 deg and 15.6 deg.
    Keywords: AERODYNAMICS
    Type: NASA-TP-1044 , L-11723
    Format: application/pdf
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  • 5
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    Monte Carlo simulation of wave sensing with a short pulse radar (1977)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A Monte Carlo simulation is used to study the ocean wave sensing potential of a radar which scatters short pulses at small off-nadir angles. In the simulation, realizations of a random surface are created commensurate with an assigned probability density and power spectrum. Then the signal scattered back to the radar is computed for each realization using a physical optics analysis which takes wavefront curvature and finite radar-to-surface distance into account. In the case of a Pierson-Moskowitz spectrum and a normally distributed surface, reasonable assumptions for a fully developed sea, it has been found that the cumulative distribution of time intervals between peaks in the scattered power provides a measure of surface roughness. This observation is supported by experiments.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NASA-TM-X-71412 , X-953-77-239
    Format: application/pdf
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  • 6
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    Low-speed wind tunnel investigation of an advanced supersonic cruise arrow-wing configuration (1977)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A preliminary assessment of possible means for improving the low speed aerodynamic characteristics of advanced supersonic cruise arrow wing configurations and to extend the existing data base of such configurations has been made. Principle configuration variables included wing-leading and trailing-edge flap deflection, fuselage nose strakes, and engine exhaust nozzle deflection. Results showed that deflecting the wing leading edge apex flaps downward provided improved longitudinal stability but resulted in reduced directional stability. The model exhibited relatively low values of directional stability over the operational angle of attack range and experienced large asymmetric yawing moments at high angles of attack. The use of nose strakes was found to be effective in increasing the directional stability and eliminating the asymmetric yawing moment.
    Keywords: AERODYNAMICS
    Type: NASA-TM-74043
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 7
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    Measurements of AAFE RADSCAT antenna characteristics (1977)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Antenna characteristics (active and passive) for a modified AAFE-RADSCAT parabolic dish antenna are documented for a variety of antenna configurations. The modified antenna was a replacement for the original unit which was damaged in January 1975. Pattern measurements made at Langley Research Center and Johnson Space Center are presented, with an analysis of the results. Antenna loss measurements are also presented and summarized.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NASA-TM-X-72844
    Format: application/pdf
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  • 8
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    Utilization of NASA Lewis mobile terminals for the Hermes satellite (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: The paper describes the portable earth terminal (PET) and the transportable earth terminal (TET) which enable two-way television and voice communication. Both terminals were developed by NASA and utilize the high power of the Hermes satellite. PET is a bus-type vehicle which has receiving equipment for full duplex color television and which can transmit programs originating in either the on-board PET studio or in nearby buildings. PET has a collapsible 2.4-m diameter parabolic antenna interfacing with a 500-watt 14-GHz wideband TV transmitter and a 12-GHz wideband TV receiver system. TET uses two parabolic reflector antennas, 3 m and 1.2 m in diameter, mounted on a flat trailer towed by a truck. TET can receive and relay color TV signals, and its narrowband transmitter can serve as a return audio link permitting a question-and-answer format. Also described are uplink and downlink performance characteristics, operation procedures, and field demonstrations which enabled personnel at several hospitals to participate in a distant medical conference.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Symposium on Hermes (Communications Technology Satellite): Its Performance and Applications; Nov 29, 1977 - Dec 01, 1977; Ottawa; Canada
    Format: text
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    NASA TECHNICAL REPORTS
  • 9
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    Non-parametric PCM to ADM conversion (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: An all-digital technique to convert pulse code modulated (PCM) signals into adaptive delta modulation (ADM) format is presented. The converter developed is shown to be independent of the statistical parameters of the encoded signal and can be constructed with only standard digital hardware. The structure of the converter is simple enough to be fabricated on a large scale integrated circuit where the advantages of reliability and cost can be optimized. A concise evaluation of this PCM to ADM translation technique is presented and several converters are simulated on a digital computer. A family of performance curves is given which displays the signal-to-noise ratio for sinusoidal test signals subjected to the conversion process, as a function of input signal power for several ratios of ADM rate to Nyquist rate.
    Keywords: COMMUNICATIONS AND RADAR
    Type: In: NTC ''77; National Telecommunications Conference; Dec 05, 1977 - Dec 07, 1977; Los Angeles, CA
    Format: text
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    NASA TECHNICAL REPORTS
  • 10
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    Computation of viscous transonic flow about a lifting airfoil (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: The Reynolds averaged Navier-Stokes equations are solved numerically for the viscous transonic flow about a stationary NACA 64A010 airfoil in free air. This paper presents descriptions of the numerical method, turbulence models employed, and boundary conditions appropriate to simulation of free-air flight. Computed results are presented for the airfoil at a free-stream Mach number of 0.8, angles of attack of 0 and 2 deg, and a Reynolds number based on a chord of 4 x 10 to the 6th. For the lifting case, unsteady periodic motion was calculated along the aft portion of the airfoil and in its wake. Recent experimental results obtained by Johnson indicate periodicity aft of the shock closely approximates the computed frequency, but the amplitude of the disturbances was significantly less than the calculated amplitude.
    Keywords: AERODYNAMICS
    Type: AIAA PAPER 77-679 , Conference on Fluid and Plasmadynamics; Jun 27, 1977 - Jun 29, 1977; Albuquerque, NM
    Format: text
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