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  • Other Sources  (628)
  • AERODYNAMICS  (420)
  • COMMUNICATIONS AND RADAR  (208)
  • 1980-1984  (627)
  • 1950-1954  (1)
  • 1982  (627)
  • 1950  (1)
  • 1
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    In-flight lift and drag measurements on a first generation jet transport equipped with winglets (1982)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: A KC-135A aircraft equipped with wing tip winglets was flight tested to demonstrate and validate the potential performance gain of the winglet concept as predicted from analytical and wind tunnel data. Flight data were obtained at cruise conditions for Mach numbers of 0.70, 0.75, and 0.80 at a nominal altitude of 36,000 ft. and winglet configurations of 15 deg cant/-4 deg incidence, 0 deg cant/-4 deg incidence, and baseline. For the Mach numbers tested the data show that the addition of winglets did not affect the lifting characteristics of the wing. However, both winglet configurations showed a drag reduction over the baseline configuration, with the best winglet configuration being the 15 deg cant/-4 deg incidence configuration. This drag reduction due to winglets also increased with increasing lift coefficient. It was also shown that a small difference exists between the 15 deg cant/-4 deg incidence flight and wind tunnel predicted data. This difference was attributed to the pillowing of the winglet skins in flight which would decrease the winglet performance.
    Keywords: AERODYNAMICS
    Type: KC-135 Winglet Program Rev.; p 103-116
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  • 2
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    KC-135 winglet program overview (1982)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: A joint NASA/USAF program was conducted to accomplish the following objectives: (1) evaluate the benefits that could be achieved from the application of winglets to KC-135 aircraft; and (2) determine the ability of wind tunnel tests and analytical analysis to predict winglet characteristics. The program included wind-tunnel development of a test winglet configuration; analytical predictions of the changes to the aircraft resulting from the application of the test winglet; and finally, flight tests of the developed configuration. Pressure distribution, loads, stability and control, buffet, fuel mileage, and flutter data were obtained to fulfill the objectives of the program.
    Keywords: AERODYNAMICS
    Type: KC-135 Winglet Program Rev.; p 1-46
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  • 3
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    KC-135 wing and winglet flight pressure distributions, loads, and wing deflection results with some wind tunnel comparisons (1982)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: A full-scale winglet flight test on a KC-135 airplane with an upper winglet was conducted. Data were taken at Mach numbers from 0.70 to 0.82 at altitudes from 34,000 feet to 39,000 feet at stabilized flight conditions for wing/winglet configurations of basic wing tip, 15/-4 deg, 15/-2 deg, and 0/-4 deg winglet cant/incidence. An analysis of selected pressure distribution and data showed that with the basic wing tip, the flight and wind tunnel wing pressure distribution data showed good agreement. With winglets installed, the effects on the wing pressure distribution were mainly near the tip. Also, the flight and wind tunnel winglet pressure distributions had some significant differences primarily due to the oilcanning in flight. However, in general, the agreement was good. For the winglet cant and incidence configuration presented, the incidence had the largest effect on the winglet pressure distributions. The incremental flight wing deflection data showed that the semispan wind tunnel model did a reasonable job of simulating the aeroelastic effects at the wing tip. The flight loads data showed good agreement with predictions at the design point and also substantiated the predicted structural penalty (load increase) of the 15 deg cant/-2 deg incidence winglet configuration.
    Keywords: AERODYNAMICS
    Type: KC-135 Winglet Program Rev.; p 47-102
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  • 4
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    A new SPS antenna design to reduce grating lobes (1982)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: In the Solar Power Satellite system, the antenna's misalignment will produce well defined grating lobes. These gratings lobe peaks occur every 440 km and are potentially hazardous to the environment. One way to suppress these peaks is to phase control every power module. The cost due to the increase in receiving electronics and processors, however, could prove to be prohibitive. A new design of the antenna involving the addition of two broad gaps, one along the x axis and another along the y axis is proposed. The gap distance is exactly one half of the distance between the center of two neighboring subarrays. Calculation of far field radiation patterns shows that the design reduces grating lobe peaks without sacrificing power in the main lobe.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The 1981 NASA(ASEE Summer Fac. Fellowship Program; 14 p
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  • 5
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    Miniature voice output communication aid (1982)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Keywords: COMMUNICATIONS AND RADAR
    Type: NASA Technol. Appl. Team; p 20
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  • 6
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    Low gain and steerable vehicle antennas for communications with land mobile satellite (1982)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Current development activities at JPL for ground mobile vehicle antennas to be used with the Land Mobile Satellite Service (LMSS) system are described. Both low gain and electronically steerable high gain type antennas are discussed in terms of their design concept and RF performance. For the low gain type, three classes of antennas are under various stages of development. These are the crossed-drooping dipole, quadrifilar helix, and microstrip patch designs. The antennas are intended to provide circularly-polarized radiation with a minimum of 3-dB gain in the angular region from 19 degrees to 60 deg from the horizon in elevation plane and with an omnidirectional pattern in azimuthal plane. For the electronically steerable high gain type, circularly-polarized microstrip patch phased arrays formed on a planar surface and on the surface of a truncated cone are under study. The arrays are intended to provide a minimum of 12 dB gain in the same angular region in elevation plane at all azimuthal angles. This coverage is accomplished by scanning the high gain pencil beam in both elevation and azimuthal directions. Both types of antennas are to transmit at 821-831 MHz band and to receive at 866-876 MHz band. They must be of low cost design and reasonably conformal to the vehicle.
    Keywords: COMMUNICATIONS AND RADAR
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  • 7
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    Concept for advanced satellite communications and required technologies (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The advanced communications technology satellite (ACTS) program of NASA is aimed at the development of high risk technologies that will enable exploiting higher frequency bands and techniques for improving frequency reuse. The technologies under development include multiple beam spacecraft antennas, on-board switching and processing, RF devices and components and advanced earth stations. The program focus is on the Ka-band (30/20 GHz) as the implementing frequency since it has five times the bandwidth of either the C- or Ku-bands. However, the technology being developed is applicable to other frequency bands as well and will support a wide range of future communications systems required by NASA, other Government agencies and the commercial sector. An overview is presented of an operational 30/20 GHz satellite system that may evolve. How the system addresses service requirements is discussed, and the technology required and being developed is considered. Previously announced in STAR as N83-11210
    Keywords: COMMUNICATIONS AND RADAR
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  • 8
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    An advanced generation land mobile satellite system and its critical technologies (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A conceptual design for a Land Mobile Satellite System (LMSS) for the 1990s is presented. LMSS involves small tranceivers accessing satellites directly, with ground reception through small car-top antennas. The satellite would have a large antenna and blanket coverage areas in the UHF. The call may originate from a home, be carried by wire to a gateway, transmitted to satellite on the S-band, converted to UHF on the satellite, and transmitted to the vehicle. The system design is constrained by the number of users in an area during the busiest hours, Shuttle storage, controllability factors, and the total area served. A 55-m antenna has been selected, with 87 spot beams and two 10 MHz UHF bands in the 806-890 MHz band. A 17 dB interbeam isolation level is required, implying that sufficient sub-bands can be generated to assure 8265 total channels. The mobile satellite (MSAT) would have an 83 m mast lower segment, a 34 m upper segment, and a second, 10 m antenna made of a deployable mesh. Various antenna function modes are considered.
    Keywords: COMMUNICATIONS AND RADAR
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  • 9
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    TDM/FM/FDMA - A modulation technique for multiple-beam satellites which precludes cochannel interference and allows non-uniform geographic distribution of user channels (1982)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: The technique outlined in this paper is intended to eliminate the problems of cochannel interference and uniform geographic distribution of user channels which arise in conventional designs for a multiple spot beam communication satellite to serve mobile telephony users across the CONUS. By time multiplexing FM/FDMA signal ensembles so that only those beams operating on distinct frequency subbands are allowed to transmit concurrently, cochannel interference arising from simultaneous frequency subband reuse is precluded. Thus, time disjoint frequency reuse is accomplished over a repetitive sequence of fixed time slots. By assigning different size subbands to each time slot, a market of nonuniform users can be accommodated. The technique results in a greatly simplified antenna feed system design for the satellite, at a cost of imposing the need for time slot synchronization on the mobile FM receivers whose ability for rejecting adjacent channel interference is somewhat diminished.
    Keywords: COMMUNICATIONS AND RADAR
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  • 10
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    Space Shuttle and TDRSS telecommunications system interfaces (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The telecommunications system interfaces between the spacecraft and the space shuttle, and between the spacecraft and the Tracking and Data Relay Satellite System (TDRSS) are discussed. The payload/shuttle/ground communications network, principle end-to-end link configurations, and requirements for attached and detached payloads are addressed.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Deep Space Telecommun. Systems Eng.; p 557-596
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  • 11
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    Telecommunications performance analysis and monitoring software (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The computer software used for telecommunications performance analysis and monitoring is discussed. The utilization of the TPAP analysis program for the Viking 1975 project and the Voyager 1977 project is described. The functional and design requirements for the successor system, TPAS, are also given.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Deep Space Telecommun. Systems Eng.; p 491-516
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  • 12
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    Radio frequency selection and interference prevention (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The bands available for deep-space communications, and the choice of particular mission frequencies are discussed. The more general susceptibility of deep-space Earth stations to various kinds of interference is then presented. An associated topic is the development of protection criteria that specify maximum allowable levels of interference. Next, the prediction of interference from near-Earth satellites is described, with particular emphasis on the problems and uncertainties of such predictions. Finally, a brief description of other activities aimed at the prevention or avoidance of interference to deep-space radio communications is given.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Deep Space Telecommun. Systems Eng.; p 517-555
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  • 13
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    Spacecraft antennas (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A tutorial description is given for spacecraft antennas used for deep-space-to-Earth communication. Radiation pattern parameters, pointing errors, pointing and polarization loss, and noise characteristics are discussed.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Deep Space Telecommun. Systems Eng.; p 413-460
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  • 14
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    Spacecraft radio frequency subsystem (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The historical background for the development of the planetary (RFS) is reviewed, and the performance capabilities of the various functional subassemblies are described. The flight radio frequency subsystem is a valid component for the three spacecraft telecommunications functions of tracking, command, and telemetry. It is the radio and the signal processing equipment residing in the spacecraft that interfaces with the control & data subsystem and performs two-way communications with the Earth-based Deep Space Network. The RFS consists of all the elements for RF reception, demodulation, modulation, and transmission, including those for command detection and telemetry modulation.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Deep Space Telecommun. Systems Eng.; p 383-412
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  • 15
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    Command system (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The Multimission Command (MMC) System is described. The major components within the MMC System are discussed, with the emphasis on the telecommunication-related implementations. Two versions of the spacecraft command detection system (the Viking heritage command detector and the NASA standard command detector) are discussed in detail. The former prevails in the existing flight projects and the latter will likely be adopted by the missions of the near future. The preparation of design control tables for the control of command link performance between deep space stations and the spacecraft is also discussed.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Deep Space Telecommun. Systems Eng.; p 343-381
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  • 16
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    Receiver design and performance characteristics (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The basic design, principles of operation, and characteristics of deep space communications receivers are examined. In particular, the basic fundamentals of phase-locked loop and Costas loop receivers used for synchronization, tracking, and demodulation of phase-coherent signals in residual carrier and suppressed carrier systems are addressed.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Deep Space Telcommun. Systems Eng.; p 49-121
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  • 17
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    Special characteristics of digital modulations (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The importance of the bandwidth required for transmitting the chosen signaling or modulation technique in evaluating efficiency of a communication system is noted. The direct relation between bandwidth and the power spectral density (PSD) of the signaling scheme makes efficient analytical methods for calculating the PSD essential to specifying the spectral occupancy of the transmission channel. Several techniques for calculating the PSD of synchronous data pulse streams are reviewed.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Deep Space Telecommun. Systems Eng.; p 23-47
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  • 18
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    Telecommunications systems design (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The general configuration of deep space telecommunication systems is reviewed with regard to the design criteria necessary to insure the integrity of the system's telemetry, command, and tracking functions. The signal to noise spectral density ratios that characterize telecommunications performance are defined in terms of the link parameters. For design control, a statistical approach to predict link performance and to assess its uncertainty is described.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Deep Space Telecommun. Systems Eng.; p 1-22
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  • 19
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    Turbulence amplification in shock-wave boundary-layer interaction (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Attention is directed to the acoustics research of the 1950s and 1960s for guidance in understanding and quantizing the turbulence amplification that can occur in regions of shock-wave boundary-layer interaction. Three primary turbulence amplifier-generator mechanisms are identified and shown, by linear analysis, to be responsible for turbulence amplification across a shock wave in excess of 100% of the incident turbulence intensity.
    Keywords: AERODYNAMICS
    Type: AIAA Journal; 20; July 198
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  • 20
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    Adaptive arrays - A new approach to the steady-state analysis (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A closed-form expression for the steady-state output signal-to-noise ratio (SNR) of an n-element adaptive array excited by one desired narrow-band signal and K - 1 narrow-band jammers is obtained. This is facilitated by representing each excitation by a complex n-dimensional vector - the excitation vector. It is shown that the important system parameters are functions of scalar products of pairs of these excitation vectors. In particular, the normalized output SNR of the array is shown to be the ratio of determinants whose elements involve these scaler products. Such determinants are also shown to be involved in the expressions for the optimal array weights.
    Keywords: COMMUNICATIONS AND RADAR
    Type: IEEE Transactions on Antennas and Propagation; AP-30; Jan. 198
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  • 21
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    New CCIR papers on telecommunications for deep space research (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The selection of preferred frequency bands for deep space telecommunications in the 20 to 120 GHz range is discussed. The performance of links between Earth stations and stations in deep space is affected by the atmosphere of the Earth. Attenuation and emission by the atmosphere generally limits deep space telecommunications to frequencies below 20 GHz. There are, however, certain frequency bands in the 20 to 120 GHz range where atmospheric attenuation is low enough to permit links between Earth stations and deep space stations. Additionally there are certain other bands in the 20 to 120 GHz range that would be particularly suitable for links between an Earth orbiting relay station and deep space stations.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Telecommun. and Data Acquisition Rept.; p 86-102
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  • 22
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    An experimental investigation of the changes of VLBI time delays due to antenna structural deformations (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Structural deformations primarily occur as functions of antenna elevation angle due to gravity loading. For a Cassegrain antenna, one of the major effects of structural deformation on measured VLBI time delays are those delay changes associated with axial subreflector displacement from its nominal position. Two types of time delay changes that occur when the subreflector is axially defocused are: a change which is a linear function of subreflector defocus position; and a cyclical change caused by multipath. Test results show that for the 64-m DSN antenna, the linear change is 1.8 times the subreflector defocus position, while the peak-to-peak change in cyclical variation is about + or - 3 cm when a spanned bandwidth of 38 MHz at 2290 MHz is used.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Telecommun. and Data Acquisition Rept.; p 8-16
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  • 23
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    SPF/DB titanium concepts for structural efficiency foi HC (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Illustrations for a presentation on superplastic forming/diffusion bonding titanium design concepts are presented. Sandwich skin panels with hat section, semicircular corrugation, sine wave, and truss cores are shown. The fabrication of wing panels is illustrated, and applications to the design of advanced variable sweep bombers summarized.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center Laminar Flow Control; p 95-110
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  • 24
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    SPF/DB titanium LFC porous panel concept (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Illustrations for a presentation demonstrating superplastic forming/diffusion bonding titanium porous panels are presented. Fabrication phases, sandwich panels, load bearing qualities, microstructure, and panel surface after finishing are illustrated.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center Laminar Flow Control; p 111-138
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  • 25
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    Sideband-aided receiver arraying (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Efforts to increase the amount of data that can be received from outer planet missions by coherently combining signals from ground antennas in such a way as to increase the total effective aperture of the receiving system are discussed. As these signals become weaker, the baseband arraying technique in current use degrades somewhat due to carrier jitter. One solution to this problem is Sideband-Aided Receiver Arraying (SARA). In SARA, sidebands demodulated to baseband in a master receiver at the largest antenna are used to allow slave receivers in the other antennas to track the sideband power in the signal rather than the carrier power. The already existing receivers can be used in the slaves to track and demodulate the signals in either a residual carrier or a suppressed carrier environment. The resultant baseband signals from all the antennas can then be combined using existing baseband combining equiment. Computer simulations of SARA show increases in throughput (measured in data bits per second) over baseband-only combining 17 percent at Voyager 2 Uranum encounter and 31 percent at Neptune for a four-element antenna array and (7, 1/2) convolutional coding.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Telecommun. and Data Acquisition Rept.; p 39-54
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  • 26
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    The DSN radio science system Mark 3, 1980 (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The DSN Radio Science System supported the Voyager 2 Saturn encounter radio science experiments in August 1981. Support for these experiments was provided by all the Deep Space Stations of the DSN. However, the critical support for the Saturn occultation and ring scattering experiment was provided at DSS 43 by the medium-band open-loop recording system. The DSN Radio Science System is descried and the recent implementation at DSS 43 is emphasized.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Telecommun. and Data Acquisition Rept.; p 6-11
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  • 27
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    X-29A forward-swept-wing demonstrator airplane (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The X-29A is a technology demonstrator. The FSW is just one of the technologies. Others include the following: discrete variable camber, relaxed static stability, triplex digital fly-by-wire (FBW) control system, variable-incidence/close-coupled canard, aeroelastically tailored composite wing, and thin supercritical airfoil. The growth potential for additional technologies is shown.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center Wind-Tunnel(Flight Correlation, 1981; p 177-189
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  • 28
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    Opportunities for wind-tunnel/flight correlation with new Boeing airplanes (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The use of correlated data in airplane development is discussed. Areas of interest include initial airworthiness of an aircraft, low-speed configuration optimization, and high-speed configuration optimization. Data from wind tunnel tests are shown to be significant when applied to guarantee compliance, which includes fuel consumption, airspeeds, and takeoff and landing performance. The use of correlation in achieving FAA certification is also discussed.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center Wind-Tunnel-Flight Correlation, 1981; p 141-157
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  • 29
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    F-15 wind-tunnel/flight correlations (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: F-15 correlation data for longitudinal control and inlet-ramp effectiveness, and horizontal-tail setting for trim are presented. The Reynolds number effect on airfoil laminar bubble burst is included.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center Wind-Tunnel(Flight Correlation, 1981; p 109-115
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  • 30
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    Wind-tunnel/flight correlation program on XB-70-1 (1982)
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    Publication Date: 2011-08-18
    Description: The XB-70-1 was selected for a wind-tunnel/flight correlation program as representative of a large, flexible supersonic airplane similar to a supersonic transport. Tests were made to determine the effects of control deflections, wing tip deflection, and variations in inlet mass flow (additive drag).
    Keywords: AERODYNAMICS
    Type: Wind-Tunnel(Flight Correlation, 1981; p 65-91
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  • 31
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    Selection of frequencies for deep-space telecommunications (1982)
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    Publication Date: 2011-08-18
    Description: The procedures used by the Jet Propulsion Laboratory to select and recommend frequencies to be used for deep space telecommunications are explained. The frequency selection process described deals only with the potential for radio frequency interference between deep space telecommunication links. Channel plans based on bandwidth, hardware implementation, and frequency ratio considered are used. The channel selection process is based on calculations and analysis of interference-to-signal power ratios as a function of time for each possible pair of missions. The modes of interference and the interference protection ratio are explained, and the interference analysis procedure described. Equations used in calculating the downlink and uplink interference analyses are presented.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Telecommun. and Data Acquisition Rept.; p 49-61
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  • 32
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    X-29A for NTF wind-tunnel/flight correlations (1982)
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    Publication Date: 2011-08-18
    Description: Considerations and recommendations for correlation are given. Basic tunnel calibration prior to research and development tests is suggested. Areas of concentration include: wing cruise drag and drag rise, wing separation and stall, afterbody and base drag, propulsion effects, vortex flows, cavity flows, and excrescences.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center Wind-Tunnel(Flight Correlation, 1981; p 191-197
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  • 33
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    Space-vehicle correlation of ground and flight experiments (1982)
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    Publication Date: 2011-08-18
    Description: A 2-percent-scale model was designed for testing in the NTF. This model has remotely controlled elevons, body flap, and rudder to minimize tunnel entries associated with configuration changes in the NTF. The Shuttle Orbiter has a very large aerodynamic data base obtained in ground facilities. Since the vehicle flight-test program has already begun, a large amount of flight data can be analyzed and correlated with the NTF results.
    Keywords: AERODYNAMICS
    Type: Wind-Tunnel(Flight Correlation, 1981; p 173-176
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  • 34
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    Aerodynamic comparisons of Space Shuttle ascent: STS-1 flight versus wind-tunnel predictions (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: It is found from the comparisons that large longitudinal aerodynamic differences exist between wind tunnel predictions and flight measurements. Cold gas plume simulation underpredicted Shuttle base pressure. It is concluded that observed flight prediction increments are probably caused by several factors such as input error, independent variable errors, plume effects, and Reynolds number effects.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center Wind-Tunnel(Flight Correlation, 1981; p 133-140
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  • 35
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    Problems in correlation caused by propulsion systems (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Correlation efforts and selected results for transonic drag are reviewed. A process to reduce the typical error sources to decrease the errors inherent in the transonic aircraft development process is summarized.
    Keywords: AERODYNAMICS
    Type: Wind-Tunnel(Flight Correlation, 1981; p 93-108
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  • 36
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    Wind-tunnel/flight-drag correlation (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Predicted and flight-test drag on the C-5A and the C-141 are correlated. Equivalent rigid flight-test profile drag and a rigid estimate based on wind tunnel data are also correlated. Correlations for the National Transonic Facility are included.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center Wind-Tunnel(Flight Correlation, 1981; p 33-46
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  • 37
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    Review of the 1980 Wind-Tunnel/Flight Correlation Panel (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Wind tunnel/flight correlation history from the P-51 to the F-8 supercritical wing is reviewed, showing that researchers continue to be faced with nearly identical discrepancies in predicted versus measured drag. The capabilities of the National Transonic Facility to allow assessment of the effects which have heretofore plagued researchers and aircraft designers are anticipated.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center Wind-Tunnel(Flight Correlation, 1981; p 23-32
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  • 38
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    Transonic-flow computation using an explicit-implicit method (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The explicit-implicit predictor corrector method of MacCormack (1981) is applied to the analysis of flows past airfoils. By comparing results obtained with different methods and meshes, it is shown that the above method provides, after certain modifications, reasonably good predictions of inviscid and viscous flows about an airfoil. Good results are also obtained for the transonic regime if the free-stream conditions are correct and if a suitable mesh is used.
    Keywords: AERODYNAMICS
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  • 39
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    Signalling characteristics in satellite-aided land mobile communications (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The feasibility of land mobile radio communications has been demonstrated by a large number of experiments with NASA's ATS satellites. Significant differences in the propagation characteristics of satellite and terrestrial mobile signal paths were observed in the experiments. Terrestrial paths are best in cities where they can provide frequency reuse and assure communication by bouncing signals around obstructions. Satellites may be best in thinly populated areas because they eliminate the need for many tower mounted relays. The satellite paths do not have the severe Rayleigh fading that limits the range and signal quality of terrestrial paths if the satellite is above approximately ten degrees elevation, a value easily achieved for the United States. The experiments verified that high quality voice communications and other functions, such as data transmission and vehicle position surveillance, are easily accomplished through geostationary satellites with vehicle transmitter power and antenna gain no different than those of terrestrial mobile communications.
    Keywords: COMMUNICATIONS AND RADAR
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  • 40
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    Observations of tropospheric phase scintillations at 5 GHz on vertical paths (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The article presents observations of turbulence-induced tropospheric phase fluctuations measured at 5 GHz on the near-vertical paths relevant to many astronomical and geophysical measurements. The data are summarized as phase power spectra, structure functions, and Allan variances. Comparisons to other microwave observations indicate relatively good agreement in both the level and shape of the power spectrum of these tropospheric phase fluctuations. Implications for precision Doppler tracking of spacecraft and geodesy/radio interferometry are discussed.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Radio Science; 17; Nov
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  • 41
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    On the impingement of supersonic jet on a normal flat surface (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: An improved method, based on one strip approximation of the method of integral relations which was reported originally by Belov, Ginzburg and Shub (1973), is presented for the calculation of flow parameters in the impingement region of a supersonic, underexpanded jet striking a normal surface located within the first cell. The results are presented for two impingement conditions and found to be in good agreement with the experimental data.
    Keywords: AERODYNAMICS
    Type: Aeronautical Quarterly; 33; Aug. 198
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  • 42
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    Pressure distributions and shock shapes for a bent-nose biconic at incidence (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Initial results of a NASA study of the lift-drag characteristics of a 12.84/7 deg biconic model intended for airbraking during atmospheric entry of probes to Mars, Venus, Saturn, and Titan are reported. Pressure distributions and shock shapes were measured in the Langley 20 in. Mach 6 tunnel with the spherically blunted bent-nose model set at angles from 0-25 deg. Pressure distributions and shock shapes where computed using the STEIN flowfield code, which features a MacCormack scheme to integrate the three-dimensional Euler equations, the Rankine-Hugoniot jump conditions to model shock waves as discontinuities, and requires a supersonic condition at every step. A comparison was made between measured and predicted values. The leeward shock angle was found to be predictable to within 3% for all angles of attack, while parabolized Navier-Stokes equations are regarded as offering more accurate results than the STEIN code for surface pressure distributions.
    Keywords: AERODYNAMICS
    Type: AIAA Journal; 20; Aug. 198
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  • 43
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    Chordwise and compressibility corrections for arbitrary planform slender wings (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The Lomax and Sluder method for adapting slender-wing theory to delta or rectangular wings by making chordwise and compressibility corrections is extended to cover wings of any arbitrary planform in subsonic and supersonic flows. The numerical accuracy of the present work is better than that of the Lomax-Sluder results. Comparison of the results of this work with those of the vortex-lattice method and Kernel function method for a family of Gothic and arrowhead wings shows good agreement. A universal curve is proposed for the evaluation of the lift coefficient of a low aspect ratio wing of an arbitrary planform in subsonic flow. The location of the center of pressure can also be estimated.
    Keywords: AERODYNAMICS
    Type: AIAA Journal; 20; Aug. 198
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  • 44
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    An explanation for the systematic flow of plasma in the solar transition region (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Using numerical simulations, it is shown that the systematic flow of plasma along a coronal magnetic flux tube is easily produced by a change in the spatial dependence of the heating rate from a symmetric deposition which supports a stationary equilibrium to a time-independent asymmetric deposition. The velocity of the flow is roughly proportional to the heating symmetry and is directed to the side of the loop away from the bulk of the energy deposition.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Astrophysical Journal; vol. 258
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  • 45
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    Numerical investigation of turbulent channel flow (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: (Previously announced in STAR as N81-30385)
    Keywords: AERODYNAMICS
    Type: Journal of Fluid Mechanics; 118; May 1982
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  • 46
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    Wind-tunnel wall interference corrections for three-dimensional flows (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A procedure for the evaluation of wall interference corrections for three-dimensional aircraft configurations is presented. The Mach number and angle-of-attack corrections are obtained by numerically solving the Laplace equation in a parallelepiped with boundary conditions supplied mainly from experimental pressure measurements. A portion of these measurements and other wind-tunnel data required by the procedure may be replaced by theoretical estimates if not available from experiments. The accuracy of the correction results will then depend on the accuracy of these estimates. The correction procedure is applied to an isolated wing and to a wing-tail configuration in a solid-wall wind tunnel. It is found that neglecting twist and camber corrections for the wing effectively increases the tail angle-of-attack correction. Two different Mach number corrections can be calculated for the wing and tail. However, since only one Mach number correction is allowed for both the wing and the tail, and since the wing surface area is larger than the tail surface area, the final correction tends to be closer to the required wing correction. This is a source of error for the tail results.
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft; 19; June 198
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  • 47
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    Validation of LTRAN2-HI by comparison with unsteady transonic experiment (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: (Previously announced in STAR as N81-29092)
    Keywords: AERODYNAMICS
    Type: AIAA Journal; 20; May 1982
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  • 48
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    Environmentally induced discharges on satellites (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A discharge process whose trigger conditions are a negative exposed metallic surface surrounded by a less negative dielectric, and a large voltage gradient at a dielectric/metal interface is proposed. Analysis of SCATHA data for a discharge substantiates the postulation. Surface discharges cause a small transient charge transfer to space which results in voltage transients. A method of computing these transients, based on the charge lost through the capacitance to space and a fraction of charge stored in the dielectric at the discharge source was developed. It gives an estimate of the discharge transients at the discharge site, which is used as input for coupling code analysis of structure/system response. The transient computations were applied to a three-axis stabilized, geosynchronous satellite for both sunlight and eclipse charging. The energy of the transient pulses are about 1 mJ for sunlight discharge and 8 mJ for eclipse. Changing of selected coatings on the satellite would relieve the stress.
    Keywords: COMMUNICATIONS AND RADAR
    Type: ESA 2nd ESTEC Spacecraft Electromag. Compatibility Seminar; p 161-172
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  • 49
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    Input impedance of microstrip antennas (1982)
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    Publication Date: 2011-08-18
    Description: Using Richmond's reaction integral equation, an expression is derived for the input impedance of microstrip patch antennas excited by either a microstrip line or a coaxial probe. The effects of the finite substrate thickness, a dielectric protective cover, and associated surface waves are properly included by the use of the exact dyadic Green's function. Using the present formulation the input impedance of a rectangular microstrip antenna is determined and compared with experimental and earlier calculated results.
    Keywords: COMMUNICATIONS AND RADAR
    Type: IEEE Transactions on Antennas and Propagation; AP-30; July 198
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  • 50
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    Far-field radiation patterns of Y and T shaped arrays with Chebyshev loading (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The far-field radiation patterns for Chebyshev loaded Y- and T-shaped array antennas are given for a number of cases. Included are full- and half-length loaded array arms. The goal of the investigation is to determine the effect of different Chebyshev loading arrangements on this type of array. It is found that in both the Y- and T-shaped arrays, the main lobes are defined by the shape of the array and that the level of the side-lobes is mainly dependent on the Chebyshev loading (that is, complete or partial).
    Keywords: COMMUNICATIONS AND RADAR
    Type: IEEE Transactions on Antennas and Propagation; AP-30; July 198
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  • 51
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    Scattering by Pruppacher-Pitter raindrops at 30 GHz (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: (Previously announced in STAR as N81-30327)
    Keywords: COMMUNICATIONS AND RADAR
    Type: Radio Science; 17; July-Aug
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  • 52
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    Large scale model measurements of airframe noise using cross-correlation techniques (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Cross-correlation techniques are used to measure the sound radiated by wing/flap airfoil configurations in the NASA-Ames 40 x 80 ft wind tunnel using a 6.7-m semispan model with three deployed flaps. The dominant source of flap noise is identified as the flap side edges, which exceeds that radiated by the midspan region by more than 10 dB. The turbulent surface eddies at the flap side edge have scales on the order of one-half the flap chord. The installation of flap actuator fairings at the flap side edge reduces the noise radiated from that location by 10 to 15 dB. The cross-correlation technique extracts airframe noise radiated by specific surface locations from the tunnel background noise, even when the noise is 25 dB higher than the measured airframe noise level.
    Keywords: AERODYNAMICS
    Type: Acoustical Society of America; vol. 71
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  • 53
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    Topological analysis of computed three-dimensional viscous flow fields (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Computed solutions of the time-dependent, Reynolds-averaged Navier-Stokes equations for three-dimensional flows having thin shear layers are analyzed, using topological concepts. Specific examples include the transonic flow over a body of revolution with conical afterbody at moderate angles of incidence to the free stream. Experimental flow-visualization techniques are simulated graphically to visualize the computed flow. Scalar and vector fluid dynamic properties, such as pressure, shear stress, and vorticity on the body surface, are presented as topological maps, and their relationship to one another in terms of orientation and singular points is discussed. The extrapolation from these surface topologies toward the understanding of external flow-field behavior is discussed and demonstrated.
    Keywords: AERODYNAMICS
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  • 54
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    KC-135A Winglet Flight Flutter Program (1982)
    In:  CASI
    Details
    Publication Date: 2014-09-11
    Description: The evaluation techniques, results and conclusions for the flight flutter testing conducted on a KC-135A airplane configured with and without winglets are discussed. Test results are presented for the critical symmetric and antisymmetric modes for a fuel distribution that consisted of 10,000 pounds in each wing main tank and empty reserve tanks. The results indicated that a lightly damped oscillation was experienced for a winglet configuration of a 0 deg cant and -4 deg incidence. The effects of cant and incidence angle variation on the critical modes are also discussed. Lightly damped oscillations were not encountered for any other winglet cant and incidence angles tested.
    Keywords: AERODYNAMICS
    Type: NASA. Dryden Flight Research Facility KC-135 Winglet Program Rev.; p 171-188
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  • 55
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    Comparison of Flight Measured, Predicted and Wind Tunnel Measured Winglet Characteristics on a KC-135 Aircraft (1982)
    In:  CASI
    Details
    Publication Date: 2014-09-11
    Description: One of the objectives of the KC-135 Winglet Flight Research and Demonstration Program was to obtain experimental flight test data to verify the theoretical and wind tunnel winglet aerodynamic performance prediction methods. Good agreement between analytic, wind tunnel and flight test performance was obtained when the known differences between the tests and analyses were accounted for. The flight test measured fuel mileage improvements for a 0.78 Mach number was 3.1 percent at 8 x 10(5) pounds W/delta and 5.5 percent at 1.05 x 10(6) pounds W/delta. Correcting the flight measured data for surface pressure differences between wind tunnel and flight resulted in a fuel mileage improvement of 4.4 percent at 8 x 10(5) pounds W/delta and 7.2 percent at 1.05 x 10(6) pounds W/delta. The performance improvement obtained was within the wind tunnel test data obtained from two different wind tunnel models. The buffet boundary data obtained for the baseline configuration was in good agreement with previous established data. Buffet data for the 15 deg cant/-4 deg incidence configuration showed a slight improvement, while the 15 deg cant/-2 deg incidence and 0 deg cant/-4 deg incidence data showed a slight deterioration.
    Keywords: AERODYNAMICS
    Type: NASA. Dryden Flight Research Facility KC-135 Winglet Program Rev.; p 145-170
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  • 56
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    Microwave noise temperature and attenuation of clouds - Statistics of these effects at various sites in the United States, Alaska, and Hawaii (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The microwave attenuation and noise temperature effects of clouds can result in serious degradation of telecommunications link performance, especially for low-noise systems presently used in deep-space communications. Although cloud effects are generally less than rain effects, the frequent presence of clouds will cause some amount of link degradation a large portion of the time. This paper presents a general review of cloud types and their water particle densities, attenuation and noise temperature calculations, and basic link signal-to-noise ratio calculations. Tabular results of calculations for 12 different cloud models are presented for frequencies in the range 10-50 GHz. Curves of average-year attenuation and noise temperature statistics at frequencies ranging from 10 to 90 GHz, calculated from actual surface and radiosonde observations, are given for 15 climatologically distinct regions in the contiguous United States, Alaska, and Hawaii. Nonuniform sky cover is considered in these calculations.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Radio Science; 17; Nov
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  • 57
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    Status of NASA advanced LFC airfoil high-lift study (1982)
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    Publication Date: 2011-08-18
    Description: The design of a high lift system for the NASA advanced LFC airfoil designed by Pfenninger is described. The high lift system consists of both leading and trailing edge flaps. A 3 meter semispan, 1 meter chord wing model using the above airfoil and high lift system is under construction and will be tested in the NASA Langley 4 by 7 meter tunnel. This model will have two separate full span leading edge flaps (0.10c and 0.12c) and one full span trailing edge flap (0.25c). The performance of this high lift system was predicted by the NASA two dimensional viscous multicomponent airfoil program. This program was also used to predict the characteristics of the LFC airfoils developed by the Douglas Aircraft Company and Lockheed-Georgia Aircraft Company.
    Keywords: AERODYNAMICS
    Type: Laminar Flow Control; p 43-62
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  • 58
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    NASA Langley laminar flow control airfoil experiment (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The design and construction of an advanced swept supercritical airfoil for commercial aircraft to be tested in a transonic wind tunnel is described. The swept LFC airfoil was designed for a given thickness ratio and lift coefficient, with emphasis placed on high critical Mach number with shock-free flow. It is compatible with satisfactory low speed and buffeting characteristics and minimizing the suction laminarization. Further emphasis was placed on achieving shock-free flow over a wide range of off-design conditions including trailing edge flap control. The requirements and design of the suction system and modifications to the Langley 8 foot transonic pressure tunnel is briefly described. Contouring of nonporous test section walls for free air simulation and flow quality improvements is included.
    Keywords: AERODYNAMICS
    Type: Laminar Flow Control; p 1-42
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  • 59
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    Special activity utilization of GDSCC antennas during 1981 (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The activities are categorized as advanced systems program, radio astronomy program, crustal dynamics program, and operations and support activities. The goals of each of the activities that received tracking support at Goldstone during 1981 are discussed. All Goldstone stations (DSSs 11, 12, 13 and 14) provided a total of 2353.55 hours of support to special activities during the period.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Telecommun. and Data Acquisition Rept.; p 121-126
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  • 60
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    Noise temperature and noise figure concepts: DC to light (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The Deep Space Network is investigating the use of higher operational frequencies for improved performance. Noise temperature and noise figure concepts are used to describe the noise performance of these receiving systems. It is proposed to modify present noise temperature definitions for linear amplifiers so they will be valid over the range (hf/kT) 1 (hf/kT). This is important for systems operating at high frequencies and low noise temperatures, or systems requiring very accurate calibrations. The suggested definitions are such that for an ideal amplifier, T sub e = (hg/k) = T sub q and F = 1. These definitions revert to the present definition for (hf/kT) 1. Noise temperature calibrations are illustrated with a detailed example. These concepts are applied to system signal-to-noise analysis. The fundamental limit to a receiving system sensitivity is determined by the thermal noise of the source and the quantum noise limit of the receiver. The sensitivity of a receiving system consisting of an ideal linear amplifier with a 2.7 K source, degrades significantly at higher frequencies.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Telecommun. and Data Acquisition Rept.; p 100-111
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  • 61
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    Provision of 9.6-kbps wideband data rate capability in the DSN (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The new 9.6-kbps wideband data rate capability in the DSN is reviewed. A functional description of the completed implementation is presented, together with a plan to upgrade the central communications terminal for additional 9.6 s operational flexibility.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Telecommun. and Data Acquisition Rept.; p 189-193
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  • 62
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    Application of Computational Fluid Dynamics (CFD) in transonic wind-tunnel/flight-test correlation (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The capability for calculating transonic flows for realistic configurations and conditions is discussed. Various phenomena which were modeled are shown to have the same order of magnitude on the influence of predicted results. It is concluded that CFD can make the following contributions to the task of correlating wind tunnel and flight test data: some effects of geometry differences and aeroelastic distortion can be predicted; tunnel wall effects can be assessed and corrected for; and the effects of model support systems and free stream nonuniformities can be modeled.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center Wind-Tunnel(Flight Correlation, 1981; p 199-215
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  • 63
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    RFI measurement survey at Goldstone in November and December 1981 (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A measurement survey was conducted to measure the emissions from the transmitters at Deep Space Station 14 and the Spaceflight Tracking and Data Network station. Both intended and spurious emissions were measured from DSN operational transmitters. The quiescent electromagnetic environment was also measured.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Telecommun. and Data Acquisition Rept.; p 110-121
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  • 64
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    An efficient sampling technique for sums of bandpass functions (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A well known sampling theorem states that a bandlimited function can be completely determined by its values at a uniformly placed set of points whose density is at least twice the highest frequency component of the function (Nyquist rate). A less familiar but important sampling theorem states that a bandlimited narrowband function can be completely determined by its values at a properly chosen, nonuniformly placed set of points whose density is at least twice the passband width. This allows for efficient digital demodulation of narrowband signals, which are common in sonar, radar and radio interferometry, without the side effect of signal group delay from an analog demodulator. This theorem was extended by developing a technique which allows a finite sum of bandlimited narrowband functions to be determined by its values at a properly chosen, nonuniformly placed set of points whose density can be made arbitrarily close to the sum of the passband widths.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Telecommun. and Data Acquisition Rept.; p 3-7
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  • 65
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    Probability of laminar flow loss because of ice crystal encounters (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A method for combining the cloud detector observation results from the Global Atmospheric Sampling Program (GASP) with Knollenberg probe observations of cloud particle concentration from other programs to derive estimates of the ambient concentration of particles larger than a given size was developed. The method was applied to estimate the probability of encountering particle concentrations which would degrade the performance of laminar flow control (LFC) aircraft. It is concluded that LF loss should occur only about one percent of the time in clear air and that flight within clouds should always result in a significant loss of LF, with 90 percent LF loss occurring about one percent of the time. Preliminary estimates of cloud encounter probability are presented for four airline routes, and conclusions are presented as to the best altitudes for cloud avoidance in extratropical and tropical latitudes.
    Keywords: AERODYNAMICS
    Type: Laminar Flow Control; p 75-94
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    Receiver-exciter controller design (1982)
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    Publication Date: 2011-08-18
    Description: A description of the general design of both the block 3 and block 4 receiver-exciter controllers for the Deep Space Network (DSN) Mark IV-A System is presented along with the design approach. The controllers are designed to enable the receiver-exciter subsystem (RCV) to be configured, calibrated, initialized and operated from a central location via high level instructions. The RECs are designed to be operated under the control of the DMC subsystem. The instructions are in the form of standard subsystem blocks (SSBs) received via the local area network (LAN). The centralized control provided by RECs and other DSCC controllers in Mark IV-A is intended to reduce DSN operations costs from the Mark III era.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Telecommun. and Data Acquisition Rept.; p 117-125
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    DSN RFI susceptibility models development program overview (1982)
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    Publication Date: 2011-08-18
    Description: The RFI model development described intended to provide an understanding of the interference susceptibility of DSN receivers. An overview of interference types and effects, analytic modelling and experimental verification is presented.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Telecommun. and Data Acquisition Rept.; p 103-109
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    Goldstone radio spectrum signal identification, March 1980 - March 1982 (1982)
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    Publication Date: 2011-08-18
    Description: The signal identification process is described. The Goldstone radio spectrum environment contains signals that are a potential source of electromagnetic interference to the Goldstone tracking receivers. The identification of these signals is accomplished by the use of signal parameters and environment parameters. Statistical data on the Goldstone radio spectrum environment from 2285 to 2305 MHz are provided.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Telecommun. and Data Acquisition Rept.; p 197-199
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  • 69
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    Applicaton of radiative transfer theory to microwave transmission medium calibrations (1982)
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    Publication Date: 2011-08-18
    Description: Precise determinations of the transmission medium loss and noise temperature contribution which are important to the performance characterization of low noise microwave receiving systems and thermal noise standards are discussed. Tropospheric loss is frequently inferred from microwave radiometer noise temperature measurements. Interpretation of these measurements requires an inversion of the radiative transfer integral equation. This is inconvenient even with computer techniques. Solutions of a rapidly convergent power series of the radiative transfer equations are presented. This solution is applicable to a low loss medium with either uniform or nonuniform loss distributions. A four layer atmosphere model is investigated to demonstrate the accuracy of the solution relative to the model. Applications include thermal noise standards and single- and dual-frequency water radiometers.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Telecommun. and Data Acquisition Rept.; p 179-188
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  • 70
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    Analysis, prediction and control of radio frequency interference with respect to DSN (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Susceptibility modeling, prediction of radio frequency interference from satellites, operational radio frequency interference control, and international regulations are considered. The existing satellite interference prediction program DSIP2 is emphasized. A summary status evaluation and recommendations for future work are given.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Telecommun. and Data Acquisition Rept.; p 81-100
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  • 71
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    RF processing (1982)
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    Publication Date: 2011-08-18
    Description: The Loran-C radio frequency processing is discussed. A diagram which generally illustrates the automatic gain control is presented. The augmented differentiator for pulse envelopes adapts conventional communications receiver with wideband AM capability to detect pulse signals such as Loran-C. The circuit enhances reception for surveillance and observation of HF over-the-horizon radar signals or others where time difference estimates between pulse returns are of interest. The high resolution VLF spectrum which receives weak VLF signals by using an HP 3581A wave analyzer detecting signals with a very narrow bandwidth of only 3 Hz is also presented.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NASA. Langley Research Center Joint Univ. Program for Air Transportation Res., 1981; p 165-172
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  • 72
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    Some ideas and opportunities concerning three-dimensional wind-tunnel wall corrections (1982)
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    Publication Date: 2011-08-18
    Description: Opportunities for improving the accuracy and reliability of wall corrections in conventional ventilated test sections are presented. The approach encompasses state-of-the-art technology in transonic computational methods combined with the measurement of tunnel-wall pressures. The objective is to arrive at correction procedures of known, verifiable accuracy that are practical within a production testing environment. It is concluded that: accurate and reliable correction procedures can be developed for cruise-type aerodynamic testing for any wall configuration; passive walls can be optimized for minimal interference for cruise-type aerodynamic testing (tailored slots, variable open area ratio, etc.); monitoring and assessment of noncorrectable interference (buoyancy and curvature in a transonic stream) can be an integral part of a correction procedure; and reasonably good correction procedures can probably be developd for complex flows involving extensive separation and other unpredictable phenomena.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center Wind-Tunnel(Flight Correlation, 1981; p 217-229
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  • 73
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    F-16E program overview and wind tunnel/flight correlation (1982)
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    Publication Date: 2011-08-18
    Description: Correlation is defined in three different ways: comparisons of wind tunnel and/or theory with flight results; detailed studies of total vehicle drag from wind tunnel and flight tests; and attempts to understand the fundamental mechanisms of fluid flows associated with aircraft components in specific areas of the flight environment. The F-16E configuration is an outgrowth of studies conducted to produce a refined fighter wing design. Several iterations required to arrive at the combination of wing planform, camber, and twist which gives near optimum lift, drag, and high-angle-of-attack stability. Theoretical analyses were backed up by extensive experimental data to validate the design and are presented
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center Wind-Tunnel(Flight Correlation, 1981; p 159-172
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  • 74
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    Aerodynamic comparisons of STS-1 Space Shuttle entry vehicle (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A conventional flight-test program, which slowly and cautiously approaches more severe flight conditions, was not possible with the Orbiter. On the first flight, the Orbiter entered the atmosphere at Mach 28 and decelerated through the Mach range. (The subsonic portion of flight was also flown by another orbiter vehicle during the Approach and Landing Test Program.) Certification for the first flight was achieved by an extensive wind-tunnel test and analysis program and by restricting the flight maneuvers severely. The initial flights of the orbiter were heavily instrumented for the purpose of obtaining accurate aerodynamic data. Even without maneuvers to excite the system, the first flight provided comparisons between flight and wind-tunnel-derived predicted data in the areas of aerodynamic performance, longitudinal trim, and reaction-control jet interaction. The aerodynamic performance comparisons are presented.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center Wind-Tunnel(Flight Correlation, 1981; p 117-131
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  • 75
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    Tunnel-to-tunnel correlation (1982)
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    Publication Date: 2011-08-18
    Description: Flow quality is discussed. Incremental comparisons of: (1) the angle of attack, (2) the axial force coefficient, and (3) the base cavity axial force coefficient against the normal force coefficient are presented. Relative blockage determination, relative buoyancy corrections, and boundary layer transition length are discussed. Blockage buoyancy caused by tunnel model wall dynamic interaction is discussed in terms of adaptive walls. The effect of 'transonic turbulence factor' is considered.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center Wind-Tunnel(Flight Correlation, 1981; p 47-63
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  • 76
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    Operations of the reconfigured Ground Communications Facility Central Communications Terminal and the Network Operations Control Center (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The ground communications facility (GCF) central communications terminal and network operations control center (NOCC) hardware was rearranged, supplemented, and modified, and software programs changed to provide an improved GCF and NOCC operational environment and capability. Control center operations section activities required to make the changeover from the old to the new GCF and NOCC configuration are addressed.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Telecommun. and Data Acquisition Rept.; p 122-129
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  • 77
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    Field interface module for antenna control assembly (1982)
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    Publication Date: 2011-08-18
    Description: The hardware aspects and capabilities of the field interface module (FIM) developed for monitor and control functions in the antenna mechanical subsystems of the deep space network and in the technical facilities controllers for the various complexes are described. The FIM is capable of monitoring and responding to a range of anaog and digital inputs and controlling external elements. The flexibility of the design makes it applicable to other control needs, using software developed for those specific applications.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Telecommun. and Data Acquisition Rept.; p 107-112
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  • 78
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    New CCIR papers on telecommunications for deep space research (1982)
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    Publication Date: 2011-08-18
    Description: Three draft reports submitted by JPL to the International Radio Consultative Committee (CCIR) for inclusion in their 1982 edition of reports and recommendations are presented. Potential interference between deep space telecommunications and the fixed satellite and broadcasting satellite services in harmonically related bands, protection criteria and sharing considerations relating to deep space research, and preferred frequencies and bandwidths for deep space research are considered.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Telecommun. and Data Acquisition Rept.; p 62-80
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  • 79
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    Radiation patterns of interfacial dipole antennas (1982)
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    Publication Date: 2011-08-18
    Description: The radiation pattern of an infinitesimal electric dipole is calculated for the case where the dipole is vertically located on the plane interface of two dielectric half spaces and for the case where the dipole is lying horizontally along the interface. For the vertical case, it is found that the radiation pattern has nulls at the interface and along the dipole axis. For the horizontal case, it is found that the pattern has a null at the interface; that the pattern in the upper half space, whose index of refraction is taken to be less than that of the lower half space, has a single lobe whose maximum is normal to the interface; and that in the lower half space, in the plane normal to the interface and containing the dipole, the pattern has three lobes, whereas in the plane normal to the interface and normally bisecting the dipole, the pattern has two maxima located symmetrically about a minimum. Interpretation of these results in terms of the Cerenkov effect is given.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Radio Science; 17; Nov
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  • 80
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    Multiple scattering calculations of rain effects (1982)
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    Publication Date: 2011-08-18
    Description: The multiple scattering calculations of rain effects are studied on the basis of calculating the incoherent intensity at 30, 60, 90, and 120 GHz. The Mie solution and the Laws-Parsons distribution are used to determine scattering and absorption characteristics. The equation of transfer and the Stokes parameters are used to determine incoherent intensities for the horizontal and vertical polarizations. The ratio of the copolarized incoherent intensity to the copolarized coherent intensity is defined as the incoherent copolarized discrimination. The ratio of the cross-polarized incoherent intensity is defined as the incoherent cross-polarized discrimination. These ratios are calculated in terms of copolarized attenuation, rain rate, and field of view. The results show that multiple scattering effects may become significant during heavy rains.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Radio Science; 17; Nov
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  • 81
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    Numerical simulation of steady supersonic flow over spinning bodies of revolution (1982)
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    Publication Date: 2011-08-18
    Description: A recently reported parabolized Navier-Stokes code has been employed to compute the supersonic flowfield about a spinning cone and spinning and nonspinning ogive cylinder and boattailed bodies of revolution at moderate incidence. The computations were performed for flow conditions where extensive measurements for wall pressure, boundary-layer velocity profiles, and Magnus force had been obtained. Comparisons between the computational results and experiment indicate excellent agreement for angles of attack up to 6 deg. At angles greater than 6 deg discrepancies are noted which are tentatively attributed to turbulence modeling errors. The comparisons for Magnus effects show that the code accurately predicts the effects of body shape for the selected models.
    Keywords: AERODYNAMICS
    Type: AIAA Journal; 20; Dec. 198
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  • 82
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    Numerical study of flowfields about asymmetric external conical corners (1982)
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    Publication Date: 2011-08-18
    Description: (Previously cited in issue 17, p. 3111, Accession no. A80-41562)
    Keywords: AERODYNAMICS
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  • 83
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    Wall interference evaluation from pressure measurements on control surfaces (1982)
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    Publication Date: 2011-08-18
    Description: Conventional methods for the calculation of wall interference corrections are based on boundary conditions which require a knowledge of ventilated wall porosity parameters, and which are unsuitable for deformed walls. The method described uses a simple exponential decay of pressure distribution beyond the most upstream and downstream limits in order to evaluate Mach number and incidence corrections given by the method proposed by Papelier et al. (1978). It is found that, while the upstream contribution to incidence correction is significant, the upstream and downstream contributions to Mach number correction are negligible.
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft; 19; Dec. 198
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  • 84
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    Airframe effects on a top-mounted fighter inlet system (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: (Previously cited in issue 07, p. 963, Accession no. A82-19212)
    Keywords: AERODYNAMICS
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  • 85
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    The velocity field induced by a helical vortex filament (1982)
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    Publication Date: 2011-08-18
    Description: An exact analytical solution for the velocity field, both interior and exterior, induced by an infinite right-handed helical vortex filament is derived. Due to the way the variables combine in this solution, the paper also shows that it is possible to derive a stream function for this nonaxisymmetric flow. Sample calculations of these expressions are included.
    Keywords: AERODYNAMICS
    Type: Physics of Fluids; 25; Nov. 198
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  • 86
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    Real-time optical synthetic aperture radar /SAR/ processor (1982)
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    Publication Date: 2011-08-18
    Description: A description is given of a real-time optical synthetic aperture radar (SAR). The processor employs an acoustooptic device as the input electronic-to-optical transducer and a CCD camera that serves as the optical detector and simultaneously performs the focusing of the SAR image in the azimuth direction. The performance criteria of the optical processor that are discussed include azimuth resolution, image size in azimuth, range resolution, image size in range, flexibility, and dynamic range.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Optical Engineering; 21; Sept
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  • 87
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    Three-dimensional shock structure in a transonic flutter cascade (1982)
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    Publication Date: 2011-08-18
    Description: Rapid double-pulse holography was employed to obtain detailed, two-dimensional images of the shock forming during simulated flutter in a transonic flowfield. The experiment comprised a linear cascade of airfoils externally oscillated in torsion and viewed tangentially at the shock surface. Three biconvex airfoils were subjected to harmonic pitching motion about the midchord axis at a frequency of 0.53 while immersed in a Mach 0.81 flow. Failure to produce observable shocks led to use of choked flow with a Mach number near one, of which 50 holograms were taken. The images revealed a narrow shock surface with a spanwise variation in the shock properties. The method is concluded to be useful for examining transonic flowfield shocks in the presence of airfoil flutter.
    Keywords: AERODYNAMICS
    Type: AIAA Journal; 20; Aug. 198
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  • 88
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    Recent advances in electromagnetic synthesis and analysis of dual-shaped reflector antennas (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Dual-shaped reflectors have been used for many years. Thus, these reflectors have been used as high gain antennas on Voyagers 1 and 2. The objectives of the geometrical optics (GO) dual shaped synthesis are considered. Concerning the synthesis of dual shaped reflectors, it has been shown for circular symmetric reflectors that an exact GO solution can be found to the problem of transforming, by two reflections, any feed pattern into any aperture distribution. This problem involves solving two simultaneous nonlinear ordinary differential equations. The same approach for offset geometry leads to two simultaneous nonlinear partial differential equations. It is shown that these equations could also be integrated numerically, except that in general these equations are not total and therefore, in general, they do not have a 'smooth' solution. It is further shown that the offset partial differentials often very nearly form a total differential in many cases of practical importance.
    Keywords: COMMUNICATIONS AND RADAR
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  • 89
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    The performance of M-ary FH-DPSK in the presence of partial-band multitone jamming (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Using a geometric approach, the performance of M-ary FH-DPSK in the presence of partial-band multitone jamming is evaluated. The optimal jamming strategy is determined as a function of the number of signaling levels M and the ensuing results are used to determine worst case bit error probability performance as a function of this same parameter. It is demonstrated that, for M = 2 to the m power (where m is an integer), the best performance is obtained for M = 4.
    Keywords: COMMUNICATIONS AND RADAR
    Type: IEEE Transactions on Communications; COM-30; May 1982
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  • 90
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    Unsteady airfoils (1982)
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    Publication Date: 2011-08-18
    Description: Progress towards successful modelling of unsteady flows past two-dimensional oscillating airfoils is examined. Linearized, thin airfoil theory is reviewed with special regard to the vortex shedding which occurs when either the body or the flow fluctuates. A sinusoidally oscillating flat-plate airfoil is considered in terms of noncirculatory components, including boundary conditions and bound and wake vortices, respectively. Applications of linear theory to vertical airfoil oscillations and to oscillating control surfaces are described, and oscillating airfoils in subsonic and supersonic flows are investigated. Perturbations in linear solutions are explored for the occurrence of second-order effects, and trailing edge and wake effects. The effects of unsteady transonic flows are broken into nearly inviscid and strongly viscous cases, and analyses of dynamic stall and stall flutter are presented.
    Keywords: AERODYNAMICS
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  • 91
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    Effect of thickness on airfoil surface noise (1982)
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    Publication Date: 2011-08-18
    Description: Noise emission from very small chord and very large chord airfoils was measured with eleven 0.63 cm microphones placed along a horizontal semicircle (4.57 m radius) that was centered at the leading edge of the test airfoil. The noise signals were analyzed by an automated spectrum analyzer which yielded 1/3-octave band sound pressure level spectra for each microphone, and the data were corrected to remove the effects of atmospheric attenuation and jet noise. It is found that the effect of thickness is large and must be accounted for in any fundamental airfoil noise theory that attempts to describe the noise emitted from real airfoils. Incident mean velocity gradients and compressibility must also be taken into account. The effect of thickness increases with frequency, with thick airfoils being quieter than thin ones.
    Keywords: AERODYNAMICS
    Type: AIAA Journal; 20; Mar. 198
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  • 92
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    Differentially coherent detection of QASK for frequency-hopping systems. II - Performance in the presence of jamming (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The performance of differentially coherent detection of frequency-hopped QASK in the presence of partial-band noise and partial-band multitone jamming is presented. In each case, the worst case jamming strategy is determined which consists of specifying the worst case partial-band fraction and the corresponding maximum average error probability. The results obtained are compared with those of M-ary FH-DPSK operating in the same jamming environment.
    Keywords: COMMUNICATIONS AND RADAR
    Type: IEEE Transactions on Communications; COM-30; Jan. 198
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  • 93
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    Differentially coherent detection of QASK for frequency-hopping systems. I - Performance in the presence of a Gaussian noise environment (1982)
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    Publication Date: 2011-08-18
    Description: Bandwidth-conserving modulation techniques, which trade average power for bandwidth in a favorable exchange, have recently found widespread application in digital radio and satellite communication systems. Quadrature amplitude-shift-keying (QASK) is a particular type of the considered techniques. QASK makes use of multilevel signals to amplitude modulate the in-phase and quadrature components of a carrier. Frequency hopping (FH) is used to protect a conventional communication system from radio frequency interference (RFI) or jamming. Differentially coherent detection provides a possible solution to the effect of phase discontinuities introduced by FH. The application of such a detection technique to QASK signals is discussed. A receiver structure is proposed and its symbol error probability performance for an additive white Gaussian noise (AWGN) background is investigated.
    Keywords: COMMUNICATIONS AND RADAR
    Type: IEEE Transactions on Communications; COM-30; Jan. 198
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  • 94
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    Analysis of separated boundary-layer flows (1982)
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    Publication Date: 2011-08-18
    Description: A method for predicting the strong interaction between the viscous and inviscid flows which occurs in flow separation is reviewed. An inverse boundary-layer procedure approximately accounts for normal pressure gradients that may be important in strongly interacting flows. Transformed boundary-layer equations are written in which the pressure gradient is set equal to the inviscid pressure gradient. As the boundary-layer edge is approached and the viscous shear and heat conduction terms vanish, the viscous flow solution is required to asymptotically approach the inviscid solution over the generalized displacement body. Attention is then focused on viscous-inviscid interacting flows with a first-order viscous formulation and constant pressure across the boundary layer. Results obtained with this procedure are presented for: (1) transitional separation bubbles near an airfoil leading edge, (2) subsonic boattail separated turbulent flow, and (3) transonic turbulent shock wave boundary-layer interaction on an axisymmetric bump configuration.
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  • 95
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    Computational aerodynamics and design (1982)
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    Publication Date: 2011-08-18
    Description: The role of computational aerodynamics in design is reviewed with attention given to the design process; the proper role of computations; the importance of calibration, interpretation, and verification; the usefulness of a given computational capability; and the marketing of new codes. Examples of computational aerodynamics in design are given with particular emphasis on the Highly Maneuverable Aircraft Technology. Finally, future prospects are noted, with consideration given to the role of advanced computers, advances in numerical solution techniques, turbulence models, complex geometries, and computational design procedures. Previously announced in STAR as N82-33348
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  • 96
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    Three-dimensional separation and reattachment (1982)
    In:  CASI
    Details
    Publication Date: 2017-10-02
    Description: The separation of three dimensional turbulent boundary layers from the lee of flight vehicles at high angles of attack is investigated. The separation results in dominant, large scale, coiled vortex motions that pass along the body in the general direction of the free stream. In all cases of three dimensional flow separation and reattachment, the assumption of continuous vector fields of skin friction lines and external flow streamlines, coupled with simple laws of topology, provides a flow grammar whose elemental constituents are the singular points: the nodes, spiral nodes (foci), and saddles. The phenomenon of three dimensional separation may be constrained as either a local or a global event, depending on whether the skin friction line that becomes a line of separation originates at a node or a saddle point.
    Keywords: AERODYNAMICS
    Type: AGARD High Angle-of-Attack Aerodyn.; 14 p
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  • 97
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    Three-dimensional flows about simple components at angle of attack (1982)
    In:  CASI
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    Publication Date: 2017-10-02
    Description: The structures of three dimensional separated flow about some chosen aerodynamic components at angle of attack are synthesized, holding strictly to the notion that streamlines in the external flow (viscous plus inviscid) and skin friction lines on the body surface may be considered as trajectories having properties consistent with those of continuous vector fields. Singular points in the fields are of limited number and are classified as simple nodes and saddles. Analogous flow structures at high angles of attack about blunt and pointed bodies, straight and swept wings, etc., are discussed, highlighting the formation of spiral nodes (foci) in the pattern of the skin friction lines. How local and global three dimensional separation lines originate and form is addressed, and the characteristics of both symmetric and asymmetric leeward wakes are described.
    Keywords: AERODYNAMICS
    Type: AGARD High Angle-of-Attack Aerodyn.; 56 p
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  • 98
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    Control of the forebody vortex orientation by asymmetric air injection. Part A: Application to enhance departure/spin recovery of fighter aircraft. Part B: Details of the flow structure (1982)
    In:  CASI
    Details
    Publication Date: 2017-10-02
    Description: A novel concept which was developed to provide powerful directional control effectiveness for a fighter aircraft at high angles of attack, where more traditional controls have very limited capability is discussed. The concept utilizes the energy concentrated in the strong forebody vortices (which form on slender bodies at high relative incidence) by controlling the lateral orientation of the vortices with respect to the body. The present concept seeks to utilize the inherent sensitivity of the vortex positioning and its bistable nature to an advantage allowing control of the forces which are developed. As it turns out, the direction or sense of the asymmetric vortex pair is much easier to control than to attenuate. The work which was done to develop the concept for application to an aircraft is described and is directed toward the effects of the concept on aircraft forces and moments and on the flight mechanics of the aircraft during maneuvering at high angles of attack. The objective was to utilize the side force associated with asymmetric vortices, in a controlled manner, to enhance the ability of the fighter to recover from a departure from controlled flight. The results from these water tunnel and wind tunnel experiments show that a small amount of tangential blowing along the forebody near the apex can effectively alter the forebody vortex system and generate large restoring yawing moments.
    Keywords: AERODYNAMICS
    Type: AGARD High Angle-of-Attack Aerodyn.; 22 p
    Format: text
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    Jet V/STOL wind-tunnel simulation and groundplane effects (1982)
    In:  CASI
    Details
    Publication Date: 2017-10-02
    Description: The pretest preparation necessary to define the objectives of an appropriate investigation into the jet V/STOL wind tunnel simulation and ground plane effects were examined. Low speed wind tunnel testing of V/STOL aircraft concepts to determine the aerodynamic propulsion interaction effects during the transition between hover and wingborne flight is a necessary step in the development cycle of this type of aircraft. Powered models are normally used to determine the aerodynamic performance characteristics. Several factors which influence the selection of the model concept and the engine simulator are discussed. Some of the test techniques important for this class of aircraft model are examined. Wind tunnel wall effects important to this aircraft testing with special emphasis on groundplane effects are reviewed.
    Keywords: AERODYNAMICS
    Type: AGARD Fluid Dyn. of Jets with Appl. to V(STOL; 21 p
    Format: text
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    The application of digital signal processing techniques to a teleoperator radar system (1982)
    In:  Other Sources
    Details
    Publication Date: 2016-06-07
    Description: A digital signal processing system was studied for the determination of the spectral frequency distribution of echo signals from a teleoperator radar system. The system consisted of a sample and hold circuit, an analog to digital converter, a digital filter, and a Fast Fourier Transform. The system is interfaced to a 16 bit microprocessor. The microprocessor is programmed to control the complete digital signal processing. The digital filtering and Fast Fourier Transform functions are implemented by a S2815 digital filter/utility peripheral chip and a S2814A Fast Fourier Transform chip. The S2815 initially simulates a low-pass Butterworth filter with later expansion to complete filter circuit (bandpass and highpass) synthesizing.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NASA. Marshall Space Flight Center The 1982 NASA(ASEE Summer Fac. Fellowship Program; 20 p
    Format: text
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