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  • Other Sources  (628)
  • AERODYNAMICS  (415)
  • ASTRONOMY  (213)
  • Animals
  • Life and Medical Sciences
  • 2005-2009
  • 1975-1979  (628)
  • 1925-1929
  • 1975  (628)
  • 1
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    Computational aerodynamics (1975)
    In:  CASI
    Details
    Publication Date: 2006-01-11
    Description: The application of computer techniques for solving Navier-Stokes equations in support of wind tunnel tests is discussed. The ILLIAC IV computer is considered for this purpose and its limitations are analyzed. The author states that improved computers will make it possible to solve many aerodynamic problems and reduce the amount of wind tunnel testing required for adequate data processing.
    Keywords: AERODYNAMICS
    Type: NASA/Univ. Conf. on Aeron.; p 211-212
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  • 2
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    On wake vortex alleviation (1975)
    In:  CASI
    Details
    Publication Date: 2006-01-11
    Description: Research within NASA relating to the nature of lift-induced vortex wakes behind large aircraft and the means whereby the hazard they represent to smaller aircraft can be alleviated is reviewed. The research, carried out in ground based facilities and in flight shows that more rapid dispersion of the wake can be effected by several means and that the modification of span-loading by appropriate flap deflection holds promise of early practical application.
    Keywords: AERODYNAMICS
    Type: NASA/Univ. Conf. on Aeron.; p 143-168
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  • 3
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    An experimental and numerical investigation of shock wave induced turbulent boundary layer separation at hypersonic speeds (1975)
    In:  CASI
    Details
    Publication Date: 2011-10-14
    Description: A thoroughly documented experiment is reported that was specifically designed to test and guide computations of the interaction of an impinging shock wave with a turbulent boundary layer. Detailed mean flow field and surface data are presented for two shock strengths which resulted in attached and separated flows, respectively. Numerical computations are used to illustrate the dependence of the computations on the particulars of the turbulence models. Models appropriate for zero pressure gradient flows predicted the overall features of the flow fields, but were deficient in predicting many of the details of the interaction regions. Improvements to the turbulence model parameters were sought through a combination of detailed data analysis and computer simulations which tested the sensitivity of the solutions to model parameter changes. Computer simulations using these improvements are presented and discussed.
    Keywords: AERODYNAMICS
    Type: AGARD Flow Separation; 13 p
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  • 4
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    On the calculation of supersonic separating and reattaching flows (1975)
    In:  CASI
    Details
    Publication Date: 2011-10-14
    Description: A method is developed for solving the laminar and turbulent compressible boundary layer equations for separating and reattaching flows. Results of this method are compared with experimental data for two laminar and three turbulent layer, shock wave interactions. Several Navier-Stokes solutions are obtained for each of the laminar boundary layer, shock wave interactions considered. Comparison of these solutions indicates a first order sensitivity in C sub f to the computational mesh selected in both the viscous and inviscid portions of the flow. Comparison of the present boundary layer solutions with the Navier-Stokes solutions and with data for a given Mach number indicates that as long as the separation bubble is small, the boundary layer approximation yields solutions whose accuracy is comparable to the Navier-Stokes solutions.
    Keywords: AERODYNAMICS
    Type: AGARD Flow Separation; 12 p
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  • 5
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    General-altitude transformations between geocentric and geodetic coordinates (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: Formulas for the general-altitude (height above the ellipsoid) transformation from geocentric to geodetic coordinates and vice versa are derived. The set of four formulas is expressed in each of two useful forms: series expansions in powers of the earth's flattening and series expansions in powers of the earth's eccentricity. The error incurred in these expansions is of the order of one part in 30 million.-
    Keywords: ASTRONOMY
    Type: Celestial Mechanics; 12; Sept
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  • 6
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    La Posta Astrogeophysical Observatory (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: An overview is presented of the equipment and data acquisition procedures at La Posta Astrogeophysical Observatory, located in the mountains, east of San Diego, Calif. It is a solar observatory, focusing on solar flares and the effect of solar activity on earth. It makes daily radio and optical observations of solar activity. Radio transmission in the earth atmosphere is monitored with VLF and HF equipment. A magnetometer monitors the state of the geomagnetic field.
    Keywords: ASTRONOMY
    Type: Solar Physics; 43; July 197
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  • 7
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    The transformation of aerodynamic stability derivatives by symbolic mathematical computation (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: The formulation of mathematical models of aeronautical systems for simulation or other purposes, involves the transformation of aerodynamic stability derivatives. It is shown that these derivatives transform like the components of a second order tensor having one index of covariance and one index of contravariance. Moreover, due to the equivalence of covariant and contravariant transformations in orthogonal Cartesian systems of coordinates, the transformations can be treated as doubly covariant or doubly contravariant, if this simplifies the formulation. It is shown that the tensor properties of these derivatives can be used to facilitate their transformation by symbolic mathematical computation, and the use of digital computers equipped with formula manipulation compilers. When the tensor transformations are mechanised in the manner described, man-hours are saved and the errors to which human operators are prone can be avoided.
    Keywords: AERODYNAMICS
    Type: Aeronautical Quarterly; 26; May 1975
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  • 8
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    Airborne infrared astronomy (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: After a brief review of the general procedures involved in airborne infrared astronomy and of the historical background leading up to this important new technique, sources of infrared radiation, effects of the earth's atmosphere on this incoming radiation, methods of detection of infrared sources, and the development of airborne observatories are described. The discussion is on a lay level; the correlation of heat with infrared emission, the primary role played by CO2 and H2O in the opacity of the atmosphere in the IR above 18 microns, the use of a crystal to electronically detect radiation in the desired spectral region, and the Lear Jet telescope as mounted in a modified C-141 cargo jet are considered.
    Keywords: ASTRONOMY
    Type: Mercury; 4; July-Aug
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  • 9
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    The low frequency sound from multipole sources in axisymmetric shear flows, with applications to jet noise (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: A closed-form solution for the sound radiation from multipole sources imbedded in an infinite cylindrical jet with an arbitrary velocity profile is obtained. It is valid in the limit where the wavelength is large compared with the jet radius. Simple formulae for the acoustic pressure field due to convected point sources are also obtained. The results show (in a simple way) how the mean flow affects the radiation pattern from the sources. For convected lateral quadrupoles it causes the exponent of the Doppler factor multiplying the far-field pressure signal to be increased from the value of 3 used by Lighthill to 5.
    Keywords: AERODYNAMICS
    Type: Journal of Fluid Mechanics; 70; Aug. 12
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  • 10
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    High-energy gamma-ray astronomy (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: The subject of gamma-ray astronomy is discussed with emphasis on celestial gamma rays with energies in excess of 10 MeV. Early observations of such gamma rays are reviewed, a gamma-ray spark-chamber telescope is described together with a gas Cerenkov-counter telescope, and the gamma-ray sky is delineated. It is shown that the diffuse high-energy gamma radiation from the galactic plane probably results primarily from cosmic-ray interactions with interstellar matter. Mechanisms for gamma-ray production are identified, and it is noted that the general galactic radiation may prove to be of great value in studies of galactic structure. Possible sources are considered for the diffuse celestial radiation, and discrete sources are described, including the Crab pulsar, the Vela remnant, the Cygnus region, and Gould's Belt. Future developments in gamma-ray astronomy are considered.
    Keywords: ASTRONOMY
    Type: Physics Today; 28; Sept
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  • 11
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    Mariner 9 observations of beta Cephei stars (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: Ultraviolet spectra of three beta Cep variables and a nonvariable star of similar spectral type were observed by the ultraviolet spectrometer on Mariner 9. A significant light variation at 1400 A may have been detected for beta Cep. The variable stars have mean ultraviolet spectra similar to that of the nonvariable star and do not show any significant short-period spectral variations.
    Keywords: ASTRONOMY
    Type: Astronomical Society of the Pacific; vol. 87
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  • 12
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    Scientific instrumentation of the Radio-Astronomy-Explorer-2 satellite (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: The instrumentation of the RAE-2 spacecraft is described. The instruments include a pair of long travelling-wave antennas, a 37-m dipole, two radiometers making one frequency scan every 144 sec, and two rapid-sampling total-power burst receivers which cover the range from 0.025 to 13.1 MHz in 32 discrete steps. Effects of terrestrial noise on RAE-1 and RAE-2 observations are discussed, and it is noted that RAE-2 is uniquely capable of observing repeated lunar occultations of strong radio sources at very low frequencies. Some observational programs are briefly noted, including observations of the galactic background distribution, measurements of lunar occultations of solar radio bursts, and searches for more radio sources among the planets, galactic objects, and extragalactic sources.
    Keywords: ASTRONOMY
    Type: Astronomy and Astrophysics; 40; 4, Ma; May 1975
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  • 13
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    Soft X-ray emission from Hercules X-1 (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; 199; July 15
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  • 14
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    Period changes in Centaurus X-3 (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: A number of mechanisms which can change the orbital period are applied to various models of Cen X-3. Only four models which give rise to feasible mechanisms are found. Possible observations which could distinguish between these models are suggested.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; 199; July 15
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  • 15
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    The light curve of CV Serpentis, the sometimes-eclipsing Wolf-Rayet star (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: New photoelectric observations of the B-magnitude of CV Ser made in 1973 and 1974 show no clear evidence of an eclipse, but they establish night-to-night variability of several percent, a systematic brightness change of 0.035 mag during a portion of the single orbit observed in 1973, and irregular flaring in 1974. We made iris photometer measurements of Harvard patrol plates taken between 1905 June and 1953 July, and find no evidence of a very deep eclipse such as observed by Hjellming and Hiltner. We present several new light curves and discuss then in the light of the recent results of Cowley et al.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; 199; July 15
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  • 16
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    The spectrum of HD 125823 /a Centauri/ (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; 199; July 1
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  • 17
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    Conclusions from the discussions on observational results of heterodyne spectroscopy in astronomy (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: Experimental results in astronomy obtained with the aid of infrared heterodyne detection techniques are considered, taking into account the detection of thermal emission with no dispersion at the intermediate frequency and observations involving molecular line detection. The tuning range of a heterodyne spectrometer and of a Fourier transform spectrometer is considered and attention is given to the selection of the appropriate technique for a specific investigative problem.-
    Keywords: ASTRONOMY
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  • 18
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    Heterodyne spectroscopy of astronomical and laboratory sources at 8.5 microns using diode laser local oscillators (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: The first 8.5 microns infrared heterodyne spectrometer has been constructed using tuneable semiconductor (PbSe) diode lasers and was used to measure absorption line profiles of N2O in the laboratory, as well as black-body emission from the moon and from Mars. Spectral information was recorded over a 200 MHz bandwidth using an 8-channel filter bank. The resolution was 25 MHz (6 millionths of a micron), and the minimum detectable (black-body) power was approximately 1 times 10 to the minus 16th power W for 8 min of integration. The results demonstrate the usefulness of heterodyne spectroscopy for the study of remote and local sources in the infrared.
    Keywords: ASTRONOMY
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  • 19
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    Studies of the infrared source CRL 2688 (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: Infrared, optical, and radio observation are described of a newly discovered galactic infrared source. Most of the radiation comes from a 1.''5 diameter infrared source at a temperature of about 150 K, but some visible emission in the form of a symmetrical highly polarized reflection nebulosity is also seen. The object could represent either a very early or a very late stage in stellar evolution.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; 198; June 15
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  • 20
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    The eclipsing binary CW Eridani (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: Results of three-color photoelectric observations of CW Eridani are presented which were made with a 30-inch telescope over the three-year period from 1970 to 1973. The times of minima are computed, solutions of the light curves are obtained, and theoretical light curves are computed from the solutions. The period is determined to be 2.72837 days, and the orbital and photoelectric elements are derived from solutions based on the idealized Russell model.
    Keywords: ASTRONOMY
    Type: Acta Astronomica; 25; 2, 19; 1975
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  • 21
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    Estimates of nonequilibrium radiation for Venus entry (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: The present investigation is an analysis of the radiation from the chemical nonequilibrium region in the shock layer about a vehicle during Venus entry. The radiation and the flow were assumed to be uncoupled. An inviscid, nonequilibrium flowfield was calculated and an effective electronic temperature was determined for the predominant radiating species. Species concentrations and electronic temperature were then input into a radiation transport code to calculate heating rates. The present results confirm earlier investigations which indicate that the radiation should be calculated using electronic temperatures for the radiating species. These temperatures are not related in a simple way to the local translational temperature. For the described mission, the nonequilibrium radiative heating rate is approximately twice the corresponding equilibrium value at peak heating.
    Keywords: AERODYNAMICS
    Type: AIAA Journal; 13; Apr. 197
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  • 22
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    Shadow of the head of Comet Kohoutek (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: An earlier reported shadow of the head of Comet Kohoutek (1973f) was not found in later photographs of the comet. However, linear dark areas were seen and are described as the space between the plasma and the dust tails. The discrepancy in earlier observations is attributed to low resolution in them. Observation of a shadow is also discounted in terms of cometary physics, due to low dust content and the weakness and curvature of the dust tail.
    Keywords: ASTRONOMY
    Type: Nature; 253; Feb. 20
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  • 23
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    A statistical technique for processing radio interferometer data (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: The output of a radio interferometer is the Fourier transform of the object under investigation. Due to the limited coverage of the Fourier plane, the reconstruction of the image of the source is blurred by the beam of the synthesized array. A maximum-likelihood processing technique is described which uses the statistical properties of the received noise-like signals. This technique has been used extensively in the processing of large-aperture seismic arrays. This inversion method results in a synthesized beam that is more uniform, has lower sidelobes, and higher resolution than the normal Fourier transform methods. The maximum-likelihood method algorithm was applied successfully to very long baseline and short baseline interferometric data.
    Keywords: ASTRONOMY
    Type: IEEE Transactions on Antennas and Propagation; AP-23; Jan. 197
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  • 24
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    The SAS-3 X-ray observatory (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: The experiment section of the Small Astronomy Satellite-3 (SAS-3) launched in May 1975 is an X-ray observatory intended to determine the location of bright X-ray sources to an accuracy of 15 arc-seconds; to study a selected set of sources over a wide energy range, from 0.1 to 55 keV, while performing very specific measurements of the spectra and time variability of known X-ray sources; and to monitor the sky continuously for X-ray novae, flares, and unexpected phenomena. The improvements in SAS-3 spacecraft include a clock accurate to 1 part in 10 billion, rotatable solar panels, a programmable data format, and improved nutation damper, a delayed command system, improved magnetic trim and azimuth control systems. These improvements enable SAS-3 to perform three-axis stabilized observations of any point on the celestial sphere at any time of the year. The description of the experiment section and the SAS-3 operation is followed by a synopsis of scientific results obtained from the observations of X-ray sources, such as Vela X-1 (supposed to be an accreting neutron star), a transient source of hard X-ray (less than 36 min in duration) detected by SAS-3, the Crab Nebula pulsar, the Perseus cluster of galaxies, and the Vela supernova remnant.
    Keywords: ASTRONOMY
    Type: APL Technical Digest; 14; Oct
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  • 25
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    Bringing wings of change - NASA's airfoil research program (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: A review is presented of progress in attaining technical objectives in three areas of semiautomatic airfoil development: software, hardware, and applications. Software objectives seek improved mathematical models and computer codes for flow analysis and design optimization for a variety of conditions. The 17-step iterative computer model used in designing the GA (W)-1 airfoil is effective but not yet fully automated; with present methods only single-point computer optimization is possible. Hardware objectives calling for improvement in test facilities and techniques are met in part by the introduction of the Langley (F-3C) wind tunnel for independent evaluation of transonic Mach number and Reynolds effects up to 12-16 million, and by a two-dimensional test section for the Langley 1/3 transonic cryogenic tunnel which will extend the Reynolds number to 50 million. The current status of low-speed, thin, and rotorcraft airfoil development programs is discussed.
    Keywords: AERODYNAMICS
    Type: Astronautics and Aeronautics; 13; Oct. 197
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  • 26
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    UBV and JHKL photometry of the radio star UX Ari = HD 21242 (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Keywords: ASTRONOMY
    Type: Acta Astronomica; 25; 2, 19; 1975
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  • 27
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    Observing prospects for Halley's comet (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: The expected path and brightness development of Halley's comet soon before and after its perihelion on February 9, 1986 are described. It is concluded that the comet will prove disappointing to most U.S. observers, since it is not expected to equal Kohoutek in peak magnitude (and since this latter comet was disappointing to the general public). Moreover, Halley's comet will be brightest (3rd magnitude) in the southern hemisphere, and increased outdoor lighting by the year 1986 will probably obscure its tail near cities.
    Keywords: ASTRONOMY
    Type: Sky and Telescope; 49; June 197
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  • 28
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    Photometric detection of extrasolar planets using L.S.T.-type telescopes (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: Detection of planets similar to the earth and Jupiter that might be circling nearby stars is possible with the large space telescope (LST), or modifications of this instrument. The use of the moon as an occulter to increase the signal-to-noise ratio and the expected photon fluxes from hypothetical planetary companions to alpha Centauri A and B, tau Ceti, and epsilon Eridani are discussed. Because Barnard's Star is a red dwarf of visual apparent magnitude 9.5, photometric detection of its hypothetical Jupiter-like companion would be difficult using the LST-occulter system described in this paper.
    Keywords: ASTRONOMY
    Type: British Interplanetary Society; vol. 28
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  • 29
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    Binary galaxy orbit statistics. I - Fixed mass and major axis (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: Averages for the projected separation, squared radial velocity difference, and the product of these, are presented for a binary galaxy system of fixed mass and major axis, but any orbital eccentricity. The average of the product varies by a factor about 3 for eccentricities from 0 to 1.0. For circular orbits, the results agree with those of Page (1952, 1960, 1961), but for linear orbits his mass estimate is too small by a factor 6. The mutual regressions of the velocity and separation on each other are calculated, and are presented in such a way as to exhibit the relative likelihood of occupation of the different parts of the regression curves. 'Isopleths' for the probability distribution are presented for a few values of the eccentricity to illustrate the underlying cause of pileup at certain parts of the regression curves. It is concluded that previous analyses were inadequate for failing to take into account that the regression curves represent in many cases a distribution that is almost wholly depopulated through most of the range. It is evident that the data are insufficient to draw a firm conclusion about the distribution of eccentricities.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; 197; May 1
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  • 30
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    Photometry of a bright filament in the Orion nebula (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: The spectrum of a bright filament in the outer portion of the Orion nebula, 14 min from the Trapezium, was studied. The temperature of the filament, derived from /N II/ lambda 5755/6583 ratio, is 9560 K. The electron density (from /S II/ lambda 6717, 6731) is low: 360 plus or minus 150 per cu cm. The ionic abundances of He(+), N(+), O(++), and S(-) are about the same as Peimbert and Costero (1969) found in regions in Orion closer to the Trapezium. It is concluded that the filament is photoionized, presumably by the Trapezium, rather than a shock front, as had originally been suspected.
    Keywords: ASTRONOMY
    Type: Astronomical Society of the Pacific; vol. 87
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  • 31
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    Interstellar scintillation of extragalactic radio sources (1975)
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    Publication Date: 2011-08-16
    Description: Observations of 12 compact extragalactic sources were made at 2695 and 8085 MHz in order to detect weak intensity fluctuations caused by interstellar scintillation. Pulsar data are used to estimate the parameters of the interstellar medium needed to interpret the measured upper limits in terms of source angular diameters which are much larger than the scintillation cutoff diameter. It is shown that the observed source rms brightness temperatures are less than 10 to the 15th K and 10 to the 14th K at 2695 and 8085 MHz, respectively, making self-absorbed proton-synchroton radiation and high-brightness coherent mechanisms unlikely. If the sources are composed of 'point' components, each source can contain no fewer than 10,000 such components.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; 197; Apr. 1
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  • 32
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    Aperture synthesis observations of galactic H II-regions (1975)
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    Publication Date: 2011-08-16
    Description: Aperture synthesis observations at 2.695 GHz and 8.085 GHz of the H II regions NRAO 591, NGC 6857, NGC 7538, M8, W3 and W49A made with the NRAO interferometer are presented. A set of Gaussian functions is derived to describe the radiation distribution of each H II region at each frequency. Fine structure is found in all regions. With the exception of the extended source in W49A, all previously known sources with high excitation parameters are resolved into smaller sources. The electron densities of individual sources range from 100 per cu cm up to 100,000 per cu cm. In NGC 6857, NGC 7538 and W49A, continuum sources smaller than 4 arc sec and with electron densities exceeding 10,000 per cu cm are found close to the known class II OH emission sources. In M8, we find a ring which seems to be split at the position of the O-star Herschel 36.
    Keywords: ASTRONOMY
    Type: Astronomy and Astrophysics; 38; 1, Ja; Jan. 197
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  • 33
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    On angular momentum transfer in binary systems (1975)
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    Publication Date: 2011-08-16
    Description: The maximum limit for the conversion of orbital angular momentum into rotational angular momentum of the mass-gaining component in a close binary system is derived. It is shown that this conversion process does not seriously affect the rate of orbital period change and can be neglected in computing the mass transfer rate. Integration of this limit over the entire accretion process results in a value for the maximum accumulated rotational angular momentum that is 3 to 4 times larger than that implied by the observed underluminosity of stars in such systems as Mu(1) Sco, V Pup, SX Aur, and V356 Sgr. It is suggested that shell stars and emission-line stars in binary systems may be produced when the core angular momentum is transferred into an envelope having a rotational angular momentum close to the maximum limit.-
    Keywords: ASTRONOMY
    Type: Royal Astronomical Society; vol. 170
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    Gamma ray astronomy (1975)
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    Publication Date: 2011-08-16
    Description: A survey of the instruments developed for gamma ray astronomy is given together with a brief summary of the current status of the observational results. These include the studies of galactic gamma ray emission, the diffuse, presumably extragalactic, gamma radiation, and localized gamma ray sources. The study of the spatial distribution of galactic gamma radiation is beginning to provide a new means for the study of galactic structure and dynamics. The diffuse emission may provide evidence of gamma ray emission in the cosmological past, although improved observations must be obtained before the picture can be clarified. The study of localized sources has shown NP0532, the Crab radio pulsar, to be a gamma ray pulsar also and strong emission from Vela may be due to supernova produced cosmic rays interacting with the remnant gas.
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  • 35
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    Counterglow from the earth-moon libration points (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: Results from the OSO-6 Rutgers Zodiacal Light Analyzer experiment show photometric perturbations above the background in the antisun line of sight. Sixteen successive lunations were examined, and the accumulated perturbations show a maximum value in the direction of the L4 and L5 earth-moon libration points. This is interpreted as a counterglow from a cloud of particles at the libration points. The average brightness of these libration clouds is 20 S10 Vis. The average angular size of the libration clouds is approximately 6 degrees. Their position varies from one lunation to the next, within an ellipsoidal zone centered on the libration-point direction, with its semimajor axis, of approximately 6 degrees, nominally in the ecliptic and its semiminor axis, of approximately 2 degrees perpendicular to the ecliptic. The position of these clouds with respect to the Lagrangian L4 and L5 points is towards the moon in the northern summer and away from the moon in the northern winter.
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  • 36
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    X-ray and gamma-ray astronomy (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: Accomplishments in the fields of X-ray and gamma ray astronomy are discussed. Data obtained from IMP and OGO satellites are analyzed to determine the sources of interplanetary radiation bursts. The energy spectrum of cosmic gamma ray bursts as observed by IMP-6 is described. The application of cooling blackbody techniques as a method for examining cosmic gamma ray bursts is reported. The experimental results and theoretical interpretation of high energy diffuse gamma rays are investigated. The structure of the SAS-2 satellite is depicted and the accomplishments are examined. Other sources of gamma radiation to include galactic fermi, Cygnus X-1, supernovae, and the planet Jupiter are proposed. Data obtained from the Pioneer 10 space probe are presented in graph form.
    Keywords: ASTRONOMY
    Type: Significant Accomplishments in Sci. and Technol.; p 34-91
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  • 37
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    Cometary Physics (1975)
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    Publication Date: 2011-08-16
    Description: A history of comets and cometary observations is presented. Emphasis is placed on the observations and characteristics of the Comet Kohoutek. A schematic drawing of a comet is included to show the structure of the nucleus, coma, dust tail, ion tail, and natural hydrogen cloud. A joint observatory for cometary research, located in New Mexico, is described. Observations of magnetic fields in comets are analyzed. Infrared spectral observations of comet structure in the 10 micron atmospheric window are reported.
    Keywords: ASTRONOMY
    Type: Significant Accomplishments in Sci. and Technol.; p 2-33
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  • 38
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    Theoretical study of lift-generated vortex wakes designed to avoid rollup (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: Two hypothetical vortex wakes are introduced and studied theoretically to explore whether the rollup of lift-generated vortex sheets can be suppressed. The circulation distribution across each wake is specified such that one rotates and the other translates as a unit due to their self-induced velocities. Several span loadings are constructed from these solutions and the resulting inviscid wake structure is computed for several span lengths behind the generating wing by use of the discrete vortex method wherein the vortex wake is represented by an array of vortices. The final distribution of vortices is then used to estimate the rolling moment on an encountering wing. It is found that, even though the initial specified motions are not sustained, substantial reductions in rolling moment are predicted for certain ranges of the ratio of the span of the generating wing to the following wing.
    Keywords: AERODYNAMICS
    Type: AIAA Journal; 13; Apr. 197
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  • 39
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    Numerical solutions for supersonic corner flow (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: Analytical solutions for inviscid supersonic corner flows are virtually nonexistent due to the complexity of the interference geometry. In view of this, numerical solutions for swept-compressive and swept-expansive corner flows are obtained. The governing equations are written in strong conservation-law form and are solved iteratively in nonorthogonal conical coordinates by use of a second-order, shock-capturing, finite-difference technique. The computed wave structure and surface pressure distributions are compared with high Reynolds number experimental data and show very good agreement. The results clearly show that supersonic corner flow at reasonably high Reynolds numbers including the effect of sweep is dominated by the inviscid field.
    Keywords: AERODYNAMICS
    Type: Journal of Computational Physics; 17; Feb. 197
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  • 40
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    Measured three-dimensional effects in transonic airfoil testing (1975)
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    Publication Date: 2011-08-16
    Description: An investigation was conducted regarding the issue of deviation from two-dimensionality in flowfield studies of a supercritical airfoil. It was found that significant three-dimensional effects occur in transonic airfoil tests, even for an aspect ratio of four. This is especially true at the supercritical Mach numbers, for which lateral propagation of disturbances is effective.
    Keywords: AERODYNAMICS
    Type: AIAA Journal; 13; Feb. 197
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  • 41
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    Aerodynamic characteristics of the planetary atmosphere experiments test entry probe (1975)
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    Publication Date: 2011-08-16
    Description: The aerodynamic characteristics of the Planetary Atmosphere Experiments Test entry probe were determined experimentally in ballistic range tests over a wide range of Mach and Reynolds numbers, and were compared with full-scale flight results. The ground facility data agreed with the full-scale data within 2 to 3% in drag coefficient, and within 5 to 10% in static stability, at the higher Mach numbers. Comparisons of the flight data with conventional wind-tunnel data indicated a significant disagreement in drag coefficient in the transonic speed range suggestive of important sting or wall interference effects. Variations in drag coefficient with Mach number were very small hypersonically, but variations with Reynolds number were of the order of 15% at a free-stream Mach number of 13 over the Reynolds number range from 10,000 to 1,000,000. Variations in the lift and static-stability curves with Mach number and Reynolds number were also defined.
    Keywords: AERODYNAMICS
    Type: Journal of Spacecraft and Rockets; 12; Jan. 197
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  • 42
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    On the computation of two- and three-dimensional steady transonic flows by relaxation methods (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: The paper is concerned with the application of the Murman and Cole (1971) relaxation scheme to steady, inviscid transonic flow problems in two and three dimensions. This scheme, which automatically accounts for weak shock waves, uses separate difference operators in elliptic and hyperbolic regions. The details of the scheme are described in terms of the original small disturbance formulation of Murman and Cole. In particular, Murman's recent (1973) introduction of fully conservative difference operators to obtain the correct shock jumps is examined. The extension to treating the exact isentropic equation is then covered with special attention given to Jameson's (to appear) rotated difference scheme for supersonic flow regions. The bulk of the discussion is related to two-dimensional procedures, and some comparisons with experiment are made, with emphasis on the effects of viscosity and wind-tunnel walls. Application of the Murman-Cole scheme is then discussed for small disturbances in three dimensions.
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  • 43
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    Multiple slot skin friction reduction (1975)
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    Publication Date: 2011-08-16
    Description: The paper investigates analytically the effect of multiple slot injection on skin friction for a representative fuselage shape (ogive-cylinder body) and evaluates the potential of slot injection as a drag reduction system in subsonic flow. Typical CTOL cruise flight conditions (Mach number equals 0.82 at altitudes of 11 km) were adopted for a fuselage 67.06 m in length and with maximum diameter of 7.32 m. The numerical method of Price and Harris (1972) was used to calculate the boundary-layer characteristics up to the first slot, while the finite-difference method of Beckwith and Bushnell (1971) was used to calculate the velocity profile downstream of one, three, five, or ten slots. An integral expression is proposed for characterizing skin friction reduction effectiveness, and it is seen that large reductions in viscous drag (50%) are available through slot injection. Skin friction reduction is improved by increasing the number of injection slots but at a diminishing rate.
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft; 12; Sept
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  • 44
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    Mach and Reynolds number effects on turbulent skin friction reduction by injection (1975)
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    Publication Date: 2011-08-16
    Description: The investigation reported is concerned with questions regarding a possible Mach number influence on skin friction reduction caused by injection. The investigation shows that data considered by Danberg (1967) for the no-blowing skin friction coefficient are in error. Accurate profiles and local skin friction coefficient values are obtained when the influence of low Reynolds number amplification in the outer region of the boundary layer is included in a calculation method.
    Keywords: AERODYNAMICS
    Type: Journal of Spacecraft and Rockets; 12; Aug. 197
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  • 45
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    Cascade with subsonic leading-edge locus (1975)
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    Publication Date: 2011-08-16
    Description: The paper investigates a two-dimensional oscillating cascade with a subsonic leading edge locus in a supersonic flow. The blades are assumed to be of small thickness and camber, and are undergoing small amplitude-harmonic oscillations. The problem is reduced to the solution of a functional integral equation, and an expression is given for the kernel function.
    Keywords: AERODYNAMICS
    Type: AIAA Journal; 13; Aug. 197
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  • 46
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    Fourier spectroscopy in planetary research (1975)
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    Publication Date: 2011-08-16
    Description: The application of Fourier Transform Spectroscopy (FTS) to planetary research is reviewed. The survey includes FTS observations of the sun, all the planets except Uranus and Pluto, The Galilean satellites and Saturn's rings. Instrumentation and scientific results are considered. The prospects and limitations of FTS for planetary research in the forthcoming years are discussed.
    Keywords: ASTRONOMY
    Type: Space Science Reviews; 18; Nov. 197
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  • 47
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    Filter wedge spectroscopy in the region 3-6 microns (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Keywords: ASTRONOMY
    Type: Nature; 257; Oct. 23
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  • 48
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    The flow over a 'high' aspect ratio gothic wing at supersonic speeds (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: Results are presented of an experimental investigation on a nonconical wing which supports an attached shock wave over a region of the leading edge near the vertex and a detached shock elsewhere. The shock detachment point is determined from planform schlieren photographs of the flow field and discrepancies are shown to exist between this and the one calculated by applying the oblique shock equations normal to the leading edge. On a physical basis, it is argued that the shock detachment has to obey the two-dimensional law normal to the leading edges. From this, and from other measurements on conical wings, it is thought that the planform schlieren technique may not be particularly satisfactory for detecting shock detachment. Surface pressure distributions are presented and are explained in terms of the flow over related delta wings which are identified as a vertex delta wing and a local delta wing.
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  • 49
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    Interstellar scattering of pulsar radiation. I - Scintillation (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: An investigation of the intensity fluctuations of 28 pulsars near 0.4 GHz indicates that spectra of interstellar scintillation are consistent with a Gaussian shape, that scintillation indices are near unity, and that the scintillation bandwidth depends linearly on dispersion measure. Observations at cm wavelengths show that the observer is in the near field of the scattering medium for objects with the lowest dispersion measures, and confirm the steep dependence of correlation bandwidth on dispersion measure found by Sutton (1971). The variations of scattering parameters with dispersion measure may indicate that the rms deviation of thermal electron density on the scale of 10 to the 11th cm grows with path length through the galaxy.
    Keywords: ASTRONOMY
    Type: Astronomy and Astrophysics; 43; 3, Oc; Oct. 197
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  • 50
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    On the analytic structure of the Taylor-Maccoll conical-flow solution (1975)
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    Publication Date: 2011-08-16
    Description: The conical flow solution for axisymmetric supersonic flow past cones has been found to be virtually independent of the ratio of specific heats when normalized in a certain way. A simple rational approximation to this flow is derived. The important singularities and the limiting behavior of the solution are also discussed.
    Keywords: AERODYNAMICS
    Type: Zeitschrift fuer angewandte Mathematik und Physik; 26; July 25
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  • 51
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    Supersonic inlet contour interpolation (1975)
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    Publication Date: 2011-08-16
    Description: A method for designing supersonic inlet contours is described which consists in the interpolation of the contours of two known inlets designed for different Mach numbers, thereby determining the contours for a third inlet at an intermediate design Mach number. Several similar axisymmetric inlet contours were interpolated from known inlets with design Mach numbers ranging from 2.16 to 4.0 and with design Mach numbers differing by as much as 1.0. The flowfields were calculated according to Sorensen's (1965) computer program. Shockwave structure and pressure distribution characteristics are shown for the interpolated inlets. The validity of the interpolation is demonstrated by comparing the plots of the flowfield properties across the throat station of the interpolated inlet with the known inlets which were designed iteratively. It seems possible to write a computer program so that a matrix of known inlet contours can be interpolated.
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft; 12; Sept
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  • 52
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    Eclipses by an elliptical torus (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: A general procedure for computing the effects of eclipses by a torus, including both the outer horizon and the inner or hole horizon, was developed. The procedure can be used for any of the simple figures of revolution encountered in binary-star models. That is, the thickness can be made negligible to produce a thin ring, the hole radius can be set to zero to yield a thin disk, the radius to the center of the elliptical meridian section can be brought to zero to give an ellipsoid of revolution, or the equatorial axis of the elliptical meridian section can be made to equal zero to produce a section of a right circular cylinder.
    Keywords: ASTRONOMY
    Type: Astronomical Journal; 80; Sept
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  • 53
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    Variations in Gegenschein polarization (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: Claims made by Bandermann and Wolstencroft (1974) that angular structure and day-to-day variations of the polarized component of the zodiacal light were observed near the antisolar point are shown to be unsubstantiated. The data obtained by Bandermann and Wolstencroft are reviewed together with the instruments they used. It is shown that the incorrect results reported were due to observation errors.
    Keywords: ASTRONOMY
    Type: Astronomy and Astrophysics; 41; 3-4,; July 197
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    A search for optical pulsations from X-ray sources near 4640-4650 A and 4686 A (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: We have searched for periodic optical pulsations from Cyg X-1, Cyg X-2, 3 U 1700 - 37, Her X-1, Sco X-1, Vela X-1, SMC X-1, WRA 977, and from the central region of the Cygnus Loop. Most observations were confined to the spectral features around 4640-4650 A and 4686 A, which are seen in most X-ray source counterparts, are known to be variable, and are likely to be associated with the X-ray emission. No optical pulsations were detected, but upper limits are established and related to the X-ray behavior.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; 200; Aug. 15
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    Recent results in ultraviolet astronomy obtained by a wide field rocket camera and the French S 183 Skylab experiment (1975)
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    Publication Date: 2011-08-16
    Keywords: ASTRONOMY
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  • 56
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    Aplanatic two-mirror telescopes - A systematic study. III - The Schwarzschild-Couder configuration (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Keywords: ASTRONOMY
    Type: Applied Optics; 14; Apr. 197
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  • 57
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    Computation of three-dimensional, inviscid supersonic flows (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: The paper sets forth in detail a method for the finite-difference computation of three-dimensional supersonic fields in an Eulerian mesh. First-, second-, and third-order finite difference schemes are examined. Attention is given to proper treatment of the impermeable and permeable boundaries encompassing the computational plane. Numerical results are presented for certain specific configurations: a conical wing-body combination, internal corner flow, a two-dimensional blunt body, an interfering shock problem, and three-dimensional inviscid supersonic flow past a shuttle-orbiter type vehicle.
    Keywords: AERODYNAMICS
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    Analysis and experimental measurement of straylight suppression systems for the large space telescope (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: A computer program for straylight suppression system design and analysis was developed to analyze various proposed LST straylight suppression systems. Simultaneously, experimental measurements are being made on a simplified LST straylight suppression system in a unique facility. The experimental measurements are being used to verify and improve the computer program. The facility represents the state-of-the-art in straylight suppression measurements, and transmission factors of 10 to the minus 12th power have been measured.
    Keywords: ASTRONOMY
    Type: Optical Engineering; 14; Nov
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  • 59
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    Series solution for the planar asymmetric blunt-body problem (1975)
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    Publication Date: 2011-08-16
    Description: Accurate semianalytic solutions to the inverse blunt-body problem have been obtained using a method of series expansion. Rational fractions are employed for series summation and analytic continuation. Angles of incidence up to 30 deg and Mach numbers as low as 2 have been considered. The maximum-entropy streamline will not wet the body surface in asymmetric flow. It may pass either above or below the stagnation streamline. Limit lines appear in the supersonic portion of the flow field, both in the shock layer and in its upstream analytic continuation.
    Keywords: AERODYNAMICS
    Type: Physics of Fluids; 18; Dec. 197
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    Hypersonic incipient separation on delta wing with trailing-edge flap (1975)
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    Publication Date: 2011-08-16
    Description: The paper reviews the experimental data on the incipient separation characteristics of planar delta wings of 75 degree sharp leading edges, with full-span trailing edge flap deflected into the windward flow. The local Reynolds number range for these investigations covered laminar, transitional and turbulent conditions. It is shown that, while turbulent boundary layer data correlates with two dimensional results, in the laminar and transitional cases, there is a nearly parallel shift to higher flap angles for incipient separation.
    Keywords: AERODYNAMICS
    Type: AIAA Journal; 13; Oct. 197
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    The night sky brightness at McDonald Observatory (1975)
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    Publication Date: 2011-08-16
    Description: Baseline observations of the night sky brightness in B and V are presented for McDonald Observatory. In agreement with earlier work by Elvey and Rudnick (1937) and Elvey (1943), significant night-to-night and same-night variations in sky brightness are found. Possible causes for these variations are discussed. The largest variation in sky brightness found during a single night is approximately a factor of two, a value which corresponds to a factor-of-four variation in airglow brightness. The data are used to comment on the accuracy of previously published surface photometry of M 81.
    Keywords: ASTRONOMY
    Type: Astronomical Society of the Pacific; vol. 87
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  • 62
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    Search for extreme ultraviolet radiation from selected stars (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: Results are reported for a search for EUV radiation between 140 and 430 A from selected objects which was conducted with a rocket-borne EUV filter photometer. The candidate objects included the bright planetary nebula NGC 2392 and the stars gamma Gem, alpha CMa, omicron-prime CMa, and gamma-2 Vel. Upper limits (2-sigma level) to the flux near 200 A are determined for the five objects, and estimates of the expected 200-A helium-continuum flux are derived for two of the stars on the basis of the hot-corona model. It is found that the calculated upper limits are at least two orders of magnitude higher than plausible flux estimates based on the hot-corona model. However, it is noted that uncertainties in the flux estimates are great enough to make the upper limits useful.
    Keywords: ASTRONOMY
    Type: Astronomy and Astrophysics; 45; 1, De; Dec. 197
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    The rocket-ultraviolet spectrum of the planetary nebula NGC 7027 (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: An ultraviolet spectrum of NGC 7027, obtained with a rocket-borne telescope, is analyzed. Absolute values are presented for the observed fluxes, and upper limits are given for the strongest predicted lines that were not observed. The results are corrected for interstellar extinction using the observed and calculated line ratios between H-beta and the hydrogenic recombination line of He II at 1640 A. The corrected C IV resonance line at 1549 A is found to be in good agreement with the intensity calculated from models, but the intercombination line of C III at 1909 A is found to be too bright by a factor of 10. This discrepancy is reduced to a factor of 4 by taking dielectric recombination into account and is eliminated by using the solar carbon abundance, which implies attenuation in the C IV line. It is shown that no appreciable number of absorbing grains can exist in the C IV-producing region of the nebula since the optical depth is of the order of 10,000 at the line center.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; 202; Dec. 1
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  • 64
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    Forward marching procedure for separated boundary-layer flows (1975)
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    Publication Date: 2011-08-16
    Description: A forward-marching procedure for separated boundary-layer flows which permits the rapid and accurate solution of flows of limited extent is presented. The streamwise convection of vorticity in the reversed flow region is neglected, and this approximation is incorporated into a previously developed (Carter, 1974) inverse boundary-layer procedure. The equations are solved by the Crank-Nicolson finite-difference scheme in which column iteration is carried out at each streamwise station. Instabilities encountered in the column iterations are removed by introducing timelike terms in the finite-difference equations. This provides both unconditional diagonal dominance and a column iterative scheme, found to be stable using the von Neumann stability analysis.
    Keywords: AERODYNAMICS
    Type: AIAA Journal; 13; Aug. 197
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  • 65
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    An experimental study of jet exhaust simulation (1975)
    In:  CASI
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    Publication Date: 2012-05-22
    Description: Afterbody drag predictions for jet aircraft are usually made experimentally with the jet exhaust flow simulated. The physical gas properties of the fluid used for the model jet exhaust can affect the accuracy of simulation of the airplane's jet exhaust plume. The effect of the accuracy of this simulation on afterbody drag was investigated by wind-tunnel tests with single engine model. In addition to unheated air as the exhaust gas, the decomposition products of three different concentrations of hydrogen peroxide were utilized. The air jet simulation consistently resulted in higher boattail drag than hydrogen peroxide simulation. The differences in drag for the various exhaust gases are attributed to different plume shapes and entrainment properties of the gases. The largest differences in drag due to exhaust gas properties were obtained for the combination of high transonic Mach numbers and high boattail angles. For these conditions, the current data indicate that the use of air to simulate a nonafterburning turbojet exhaust can result in an increase in afterbody amounting to 20 percent of the nonafterburning turbojet value.
    Keywords: AERODYNAMICS
    Type: AGARD Airframe(Propulsion Interference; 11 p
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  • 66
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    Reynolds number effects on boattail drag of exhaust nozzles from wind tunnel and flight tests (1975)
    In:  CASI
    Details
    Publication Date: 2012-05-22
    Description: A family of nacelle mounted high angle boattail nozzles was tested to investigate Reynolds number effects on drag. The nozzles were flown on a modified F-106B and mounted on scale models of an F-106 in a wind tunnel. A 19- to 1-range of Reynolds number was covered as a result of the large size differences between models and by flying over a range of altitude. In flight the nozzles were mounted behind J-85 turbojet engines. Jet boundary simulators and a powered turbojet engine simulator were used on the wind tunnel models. Data were taken at Mach numbers of 0.6 and 0.9. Boattail drag was found to be affected by Reynolds number. The effect is a complex relationship dependent upon boundary layer thickness and nozzle boattail shape. As Reynolds number was increased from the lowest values obtained with scale models, boattail drag first increased to a maximum at the lowest flight Reynolds number and then decreased.
    Keywords: AERODYNAMICS
    Type: AGARD Airframe(Propulsion Interference; 15 p
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  • 67
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    An aerodynamic load criterion for airships (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: A simple aerodynamic bending moment envelope is derived for conventionally shaped airships. This criterion is intended to be used, much like the Naval Architect's standard wave, for preliminary estimates of longitudinal strength requirements. It should be useful in tradeoff studies between speed, fineness ratio, block coefficient, structure weight, and other such general parameters of airship design.
    Keywords: AERODYNAMICS
    Type: MIT Proc. of the Interagency Workshop on Lighter than Air Vehicles; p 169-176
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  • 68
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    Overview of external Nacelle drag and interference drag (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: A historical view of multi-jet engine installations is given that emphasizes integration of the powerplant and the airframe in aircraft design for improved reduction in external nacelle drag and interference drag characteristics.
    Keywords: AERODYNAMICS
    Type: Kansas Univ. Proc. of the NASA, Ind., Univ., Gen. Aviation Drag Reduction Workshop; p 235-244
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  • 69
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    Computational aspects of the prediction of multidimensional transonic flows in turbomachinery (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The analytical prediction and description of transonic flow in turbomachinery is complicated by three fundamental effects: (1) the fluid equations describing the transonic regime are inherently nonlinear, (2) shock waves may be present in the flow, and (3) turbomachine blading is geometrically complex, possessing large amounts of curvature, stagger, and twist. A three-dimensional computation procedure for the study of transonic turbomachine fluid mechanics is described. The fluid differential equations and corresponding difference operators are presented, the boundary conditions for complex blade shapes are described, and the computational implementation and mapping procedures are developed. Illustrative results of a typical unthrottled transonic rotor are also presented.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Res. Center Aerodynamic Analyses Requiring Advanced Computers, Pt. 1; p 567-585
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  • 70
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    Simulation of turbulent transonic separated flow over an airfoil (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: A code developed for simulating high Reynolds number transonic flow fields of arbitrary configuration is described. This code, in conjunction with laboratory experiments, is used to devise and test turbulence transport models which may be suitable in the prediction of such flow fields, with particular emphasis on regions of flow separation. The solutions describe the flow field, including both the shock-induced and trailing-edge separation regions, in sufficient detail to provide the profile and friction drag.
    Keywords: AERODYNAMICS
    Type: Aerodynamic Analyses Requiring Advanced Computers, Pt. 1; p 419-436
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  • 71
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    On the calculation of supersonic, separating, and reattaching flows (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: A method is developed for solving the laminar and turbulent compressible boundary-layer equations for separating and reattaching flows. Results of this method are compared with experimental data for two laminar and three turbulent boundary-layer, shock-wave interactions. Several Navier-Stokes solutions were obtained for each of the laminar boundary-layer, shock-wave interactions considered. Comparison of these solutions indicates a first-order sensitivity in C sub f to the computational mesh selected in both the viscous and inviscid portions of the flow.
    Keywords: AERODYNAMICS
    Type: Aerodynamic Analyses Requiring Advanced Computers, Pt. 1; p 151-175
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  • 72
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    Internal and external axial corner flows (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The inviscid, internal, and external axial corner flows generated by two intersecting wedges traveling supersonically are obtained by use of a second-order shock-capturing, finite-difference approach. The governing equations are solved iteratively in conical coordinates to yield the complicated wave structure of the internal corner and the simple peripheral shock of the external corner. The numerical results for the internal flows compare favorably with existing experimental data.
    Keywords: AERODYNAMICS
    Type: Aerodynamic Analyses Requiring Advanced Computers, Pt. 1; p 643-658
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  • 73
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    Numerical computation of viscous flows on the lee side of blunt shapes flying at supersonic speeds (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: A numerical method for solving the parabolic approximation to the steady-state compressible Navier-Stokes equations is examined. The approximation neglects only the streamwise gradients of shear stress. An implicit finite difference method is used which advances the solution downstream from an initial data surface and determines the complete viscous-inviscid flow between the body and bow shock wave. It is necessary that the inviscid portion of the flow field be supersonic. Crossflow separation is determined as part of the solution. The method is applied to a 15 deg sphere-cone at 15 deg angle of attack, and the results are compared with an inviscid method-of-characteristics calculation.
    Keywords: AERODYNAMICS
    Type: Aerodynamic Analyses Requiring Advanced Computers, Pt. 1; p 531-542
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  • 74
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    Long fluid filled bags suspended by line forces (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: A previous analysis of fluid filled storage bags is extended to the case of a long fluid filled cylindrical membrane supported by uniform line loads. Cross-sectional shape, stiffness of the support system and stress resultants in the membrane are determined. The application of the numerical results to problems arising in the design of nonrigid airships is discussed.
    Keywords: AERODYNAMICS
    Type: MIT Proc. of the Interagency Workshop on Lighter than Air Vehicles; p 199-208
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  • 75
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    The planar dynamics of airships (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The forces and moments acting upon a LTA vehicle are considered in order to develop parameters describing planar motion. Similar expressions for HTA vehicles will be given to emphasize the greater complexity of aerodynamic effects when buoyancy effects cannot be neglected. A brief summary is also given of the use of virtual mass coefficients to calculate loads on airships.
    Keywords: AERODYNAMICS
    Type: MIT Proc. of the Interagency Workshop on Lighter than Air Vehicles; p 177-186
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  • 76
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    General overview of drag (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The state-of-the-art on aerodynamic drag reduction is briefly reviewed. The various elements making up the total drag of an aircraft include fuselage, wing, nacelles, trim, interference, tail, and cooling drag.
    Keywords: AERODYNAMICS
    Type: Kansas Univ. Proc. of the NASA, Ind., Univ., Gen. Aviation Drag Reduction Workshop; p 11-37
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  • 77
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    Drag of the complete configuration aerodynamic considerations, 2 (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: A number of drag items are related to the performance of a complete aircraft configuration. First, the effect of fuselage camber, wing and nacelle incidence are discussed from a viewpoint of design decision making. Second, the effect of overall cruise drag on the design gross and empty weight of the airplane is discussed. Examples show that cruise drag can have a very important influence on total airplane weight. Third, the effects of usable cruise lift-to-drag ratio and wing loading are shown to be important. Finally several research needs relating to design of the complete configuration are reviewed.
    Keywords: AERODYNAMICS
    Type: Proc. of the NASA, Ind., Univ., Gen. Aviation Drag Reduction Workshop; p 337-351
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  • 78
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    Trim Drag in the Light of Munk's Stagger Theorem (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Munk's stagger theorem holds that the induced drag of a multiplane is independent of the streamwise position (the stagger) of its lifting elements so long as the gap/span ratios and the element/element lift ratios are specified. In particular, a monoplane-tailplane or a monoplane-foreplane (canard)arrangement can be regarded as a biplane of zero gap and the trim drag due to tailplane download or foreplane upload can be readily calculated. The trim drag penalty is the same for both configurations. Relations are given for trim drag estimates for various practical arrangements.
    Keywords: AERODYNAMICS
    Type: Kansas Univ. Proc. of the NASA, Ind., Univ., Gen. Aviation Drag Reduction Workshop; p 319-329
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  • 79
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    Wing Tip Vortex Drag (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Optimization of L/D through minimizing induced drag through a detailed flow study together with force, pressure and vorticity measurements is considered. Flow visualization with neutral helium bubbles provides an excellent means of observing the effects of configuration changes.
    Keywords: AERODYNAMICS
    Type: Proc. of the NASA, Ind., Univ., Gen. Aviation Drag Reduction Workshop; p 215-233
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  • 80
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    Preservation of wing leading edge suction at the plane of symmetry as a factor in wing-fuselage design (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Most fuselage geometries cover a portion of the wing leading edge near the plane of symmetry, and it seems reasonable to expect that a large fraction of the leading edge suction which would be developed by the covered wing at high angles of attack is not developed on the fuselage. This is one of the reasons that the Oswald span efficiency factor for the wing body combination fails to approach the value predicted by lifting line theory for the isolated wing. Some traditional and recent literature on wing-body interference is discussed and high Reynolds number data on wing-body-nacelle drag are reviewed. An exposed central leading edge geometry has been developed for a sailplane configuration. Low Reynolds number tests have not validated the design concept.
    Keywords: AERODYNAMICS
    Type: Kansas Univ. Proc. of the NASA, Ind., Univ., Gen. Aviation Drag Reduction Workshop; p 107-115
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  • 81
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    Prospects and time tables for analytical estimation of the drag of complete aircraft configuration (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Analytical drag methods and wind tunnel evaluation of aircraft design features are used to identify excessive drag of general aviation aircraft with reciprocating engines.
    Keywords: AERODYNAMICS
    Type: Kansas Univ. Proc. of the NASA, Ind., Univ., Gen. Aviation Drag Reduction Workshop; p 39-41
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  • 82
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    Summary of drag clean-up tests in NASA Langley full-scale tunnel (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: This summary of drag results presents tabulations on fighter aircraft and light twin general aviation aircraft wind tunnel tests. The figures show that the friction drag for light twins is larger than that for the fighters because of the greater wetted area and the smaller wing area used for reference. Full scale tunnel tests developed the following design features contributing to excessive drag: cooling flow system, engine exhaust stacks, landing gears, control surface gaps, and wing irregularities and leakages.
    Keywords: AERODYNAMICS
    Type: Kansas Univ. Proc. of the NASA, Ind., Univ., Gen. Aviation Drag Reduction Workshop; p 43-60
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  • 83
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    An investigation of several numerical procedures for time-asymptotic compressible Navier-Stokes solutions (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The status of an investigation of four numerical techniques for the time-dependent compressible Navier-Stokes equations is presented. Results for free shear layer calculations in the Reynolds number range from 1000 to 81000 indicate that a sequential alternating-direction implicit (ADI) finite-difference procedure requires longer computing times to reach steady state than a low-storage hopscotch finite-difference procedure. A finite-element method with cubic approximating functions was found to require excessive computer storage and computation times. A fourth method, an alternating-direction cubic spline technique which is still being tested, is also described.
    Keywords: AERODYNAMICS
    Type: Aerodynamic Analyses Requiring Advanced Computers, Pt. 1; p 437-468
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  • 84
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    Subgrid or Reynolds stress-modeling for three-dimensional turbulence computations (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: A review is given of recent advances in two distinct computational methods for evaluating turbulence fields, namely, statistical Reynolds stress modeling and turbulence simulation, where large eddies are followed in time. It is shown that evaluation of the mean Reynolds stresses, rather than use of a scalar eddy viscosity, permits an explanation of streamline curvature effects found in several experiments. Turbulence simulation, with a new volume averaging technique and third-order accurate finite-difference computing is shown to predict the decay of isotropic turbulence in incompressible flow with rather modest computer storage requirements, even at Reynolds numbers of aerodynamic interest.
    Keywords: AERODYNAMICS
    Type: Aerodynamic Analyses Requiring Advanced Computers, Pt. 1; p 317-339
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  • 85
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    Solutions for incompressible separated boundary layers including viscous-inviscid interaction (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Numerical solutions are presented for the laminar and turbulent boundary-layer equations for incompressible flows with separation and reattachment. The separation angularity is avoided by using an inverse technique in which the displacement thickness is prescribed and the pressure is deduced from the resulting solution. The turbulent results appear qualitatively correct despite the use of a two-layer eddy-viscosity model which is generally assumed appropriate only for mild-pressure-gradient flows. A new viscous-inviscid interaction technique is presented in which the inviscid flow is solved inversely by prescribing the pressure from the boundary-layer solution and deducing the new displacement thickness from the solution of a Cauchy integral. Calculations are presented using this interaction procedure for a laminar flow in which separation and reattachment occur on a solid surface.
    Keywords: AERODYNAMICS
    Type: Aerodynamic Analyses Requiring Advanced Computers, Pt. 1; p 125-150
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  • 86
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    A comparison of a shock-capturing technique with experimental data for three-dimensional internal flows (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Shock-capturing solutions for an axisymmetric supersonic inlet at small angles of attack are obtained. Good overall agreement between the shock-capturing solutions and experimental data is shown except in regions of strong viscous effects or boundary-layer removal. Although the results indicate a strong potential for the use of shock-capturing or finite-difference solutions for internal flows, improvement in the ability to handle the reflection of strong shockwaves having downstream Mach numbers near 1 is needed.
    Keywords: AERODYNAMICS
    Type: Aerodynamic Analyses Requiring Advanced Computers, Pt. 1; p 623-642
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  • 87
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    Calculation of three-dimensional compressible laminar and turbulent boundary layers. Calculation of three-dimensional compressible boundary layers on arbitrary wings (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: A very general method for calculating compressible three-dimensional laminar and turbulent boundary layers on arbitrary wings is described. The method utilizes a nonorthogonal coordinate system for the boundary-layer calculations and includes a geometry package that represents the wing analytically. In the calculations all the geometric parameters of the coordinate system are accounted for. The Reynolds shear-stress terms are modeled by an eddy-viscosity formulation developed by Cebeci. The governing equations are solved by a very efficient two-point finite-difference method used earlier by Keller and Cebeci for two-dimensional flows and later by Cebeci for three-dimensional flows.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Res. Center Aerodynamic Analyses Requiring Advanced Computers, Pt. 1; p 41-76
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  • 88
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    Calculation of supersonic three-dimensional free-mixing flows using the parabolic-elliptic Navier-Stokes equations (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: A numerical method is presented which is valid for integration of the parabolic-elliptic Navier-Stokes equations. The solution procedure is applied to the three-dimensional supersonic flow of a jet issuing into a supersonic free stream. Difficulties associated with the imposition of free-stream boundary conditions are noted, and a coordinate transformation, which maps the point at infinity onto a finite value, is introduced to alleviate these difficulties. Results are presented for calculations of a square jet and varying-aspect-ratio rectangular jets. The solution behavior varies from axisymmetry for the square jet to nearly two-dimensional for the high-aspect-ratio rectangle, although the computation always calculates the flow as though it were truly three-dimensional.
    Keywords: AERODYNAMICS
    Type: Aerodynamic Analyses Requiring Advanced Computers, Pt. 1; p 543-565
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  • 89
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    Calculation of shock-separated turbulent boundary layers (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Numerical solutions of the complete, time-averaged conservation equations using several eddy-viscosity models for the Reynolds shear stress to close the equations are compared with experimental measurements in a compressible, turbulent separated flow. An efficient time-splitting, explicit difference scheme was used to solve the two-dimensional conservation equations. The experiment used for comparison was a turbulent boundary layer that was separated by an incident shock wave in a Mach 2.93 flow with a unit Reynolds number of 5.7 x 10 to the seventh power m. Comparisons of predicted and experimental values of surface pressure, shear stress along the wall, and velocity profiles are shown. One of the tested eddy-viscosity models which allows the shear stress to be out of equilibrium with the mean flow produces substantially better agreement with the experimental measurements than the simpler models. A tool is thereby provided for inferring additional information about the flow, such as static pressures in the stream, which might not be directly obtainable from experiments.
    Keywords: AERODYNAMICS
    Type: Aerodynamic Analyses Requiring Advanced Computers, Pt. 1; p 401-417
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  • 90
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    Influence of external disturbances and compressibility on free turbulent mixing (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: It is shown that disturbances in external flow can significantly affect, by as much as an order of magnitude, the turbulent mixing rate in free shear layers and that the length scale of the external flow disturbances is as important as the amplitude. The difference between the effect of wide-band and narrow-band disturbances is stressed. The model for pressure fluctuation term in the kinetic energy equation is included in a two-equation model. The reduced spreading rate in high Mach number, high Reynolds number, adiabatic, free turbulent shear layers is predicted.
    Keywords: AERODYNAMICS
    Type: Aerodynamic Analyses Requiring Advanced Computers, Pt. 1; p 341-376
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  • 91
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    Minimum Vertical Tail Drag (1975)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: Tail size requirement calculations are presented for a vertical tail performing a coordinated turn reversal at corresponding load requirements with minimum tail drag.
    Keywords: AERODYNAMICS
    Type: Kansas Univ. Proc. of the NASA, Ind., Univ., Gen. Aviation Drag Reduction Workshop; p 43-446
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  • 92
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    Some comments on trim drag (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: A discussion of data of and methods for predicting trim drag is presented. Specifically the following subjects are discussed: (1) economic impact of trim drag; (2) the trim drag problem in propeller driven airplanes and the effect of propeller and nacelle location; (3) theoretical procedures for predicting trim drag; and (4) research needs in the area of trim drag.
    Keywords: AERODYNAMICS
    Type: Proc. of the NASA, Ind., Univ., Gen. Aviation Drag Reduction Workshop; p 295-305
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  • 93
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    Nacelle drag reduction: An analytically-guided experimental program (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Modifications are proposed to standard estimating procedures, as well as the BODY computer program, which predict that the drag of two nacelles will equal the drag of the fuselage. A preliminary computer analysis that considers increased dimensions for the nacelle forebody so that the noise is relatively less blunt indicates a reduction in form drag much greater than the increase in skin friction drag attributable to increased surface area.
    Keywords: AERODYNAMICS
    Type: Kansas Univ. Proc. of the NASA, Ind., Univ., Gen. Aviation Drag Reduction Workshop; p 257-261
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  • 94
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    Time-dependent transonic flow solutions for axial turbomachinery (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Three-dimensional unsteady transonic flow through an axial turbomachine stage is described in terms of a pair of two-dimensional formulations pertaining to orthogonal surfaces, namely, a blade-to-blade surface and a hub-to-casing surface. The resulting systems of nonlinear, inviscid, compressible equations of motion are solved by an explicit finite-difference technique. The blade-to-blade program includes the periodic interaction between rotor and stator blade rows. Treatment of the boundary conditions and of the blade slipstream motion by a characteristic type procedure is discussed in detail. Harmonic analysis of the acoustic far field produced by the blade row interaction, including an arbitrary initial transient, is outlined. Results from the blade-to-blade program are compared with experimental measurements of the rotating pressure field at the tip of a high-speed fan. The hub-to-casing program determines circumferentially averaged flow properties on a meridional plane. Blade row interactions are neglected in this formulation, but the force distributions over the entire blade surface for both the rotor and stator are obtained. Results from the hub-to-casing program are compared with a relaxation method solution for a subsonic rotor. Results are also presented for a quiet fan stage which includes transonic flow in both the rotor and stator and a normal shock in the stator.
    Keywords: AERODYNAMICS
    Type: Aerodynamic Analyses Requiring Advanced Computers, Pt. 1; p 587-621
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  • 95
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    Calculation of three-dimensional compressible laminar and turbulent boundary flows. Three-dimensional compressible boundary layers of reacting gases over realistic configurations (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: A three-dimensional boundary-layer code was developed for particular application to realistic hypersonic aircraft. It is very general and can be applied to a wide variety of boundary-layer flows. Laminar, transitional, and fully turbulent flows of compressible, reacting gases are efficiently calculated by use of the code. A body-oriented orthogonal coordinate system is used for the calculation and the user has complete freedom in specifying the coordinate system within the restrictions that one coordinate must be normal to the surface and the three coordinates must be mutually orthogonal.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Res. Center Aerodynamic Analyses Requiring Advanced Computers, Pt. 1; p 77-99
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  • 96
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    Calculation of three-dimensional compressible laminar and turbulent boundary layers. An implicit finite-difference procedure for solving the three-dimensional compressible laminar, transitional, and turbulent boundary-layer equations (1975)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: An implicit finite-difference procedure is presented for solving the compressible three-dimensional boundary-layer equations. The method is second-order accurate, unconditionally stable (conditional stability for reverse cross flow), and efficient from the viewpoint of computer storage and processing time. The Reynolds stress terms are modeled by (1) a single-layer mixing length model and (2) a two-layer eddy viscosity model. These models, although simple in concept, accurately predicted the equilibrium turbulent flow for the conditions considered. Numerical results are compared with experimental wall and profile data for a cone at an angle of attack larger than the cone semiapex angle. These comparisons clearly indicate that the numerical procedure and turbulence models accurately predict the experimental data with as few as 21 nodal points in the plane normal to the wall boundary.
    Keywords: AERODYNAMICS
    Type: Aerodynamic Analyses Requiring Advanced Computers, Pt. 1; p 17-40
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  • 97
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    Distance to Cygnus X-1 (1975)
    In:  Other Sources
    Details
    Publication Date: 2019-01-25
    Keywords: ASTRONOMY
    Type: Res. in the Space Sci., vol. 2, no.2; 70 p
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  • 98
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    A numerical determination of the bow shock wave in transonic axisymmetric flow about blunt bodies (1975)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A numerical method was developed for calculating axisymmetric transonic (M greater than 1) flow about a blunt body; the bow shock wave location was investigated. A Rankine-Hugoniot jump was applied at the shock while relaxation on the isentropic equation of motion was used between shock and body. The shock wave is adjusted by a Newton type iteration scheme. Results are given for a sphere in the Mach number range 1.62 down to 1.02.
    Keywords: AERODYNAMICS
    Type: NASA-TM-X-72448 , NRC-14765 , LR-586 , (ISSN 0077-5541)
    Format: application/pdf
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  • 99
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    Wind tunnel investigation of an oblique wing transport model at mach numbers between 0.6 and 1.4 (1975)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Models of three practical oblique-wing transport configurations were tested in the NASA Ames 11 foot wind tunnel. The three configurations used a common forward fuselage, wing, and support system but employed different aft fuselage sections simulating alternate propulsion system installations. These included an integrated propulsion system, pylon-mounted nacelles, and clean (no propulsion system) configuration. The tests were conducted over a Mach number range from 0.6 to 1.4 and at sweep angles from 0 to 60 degrees. The nominal unit Reynolds number was 1.83 million per meter and the angle of attack range was -3 to +6 degrees. The models were mounted in the tunnel by means of a lower blade support system. The interference effects of this lower blade and the flow inclination were determined by using an image blade system and testing the configuration in both the upright and inverted positions.
    Keywords: AERODYNAMICS
    Type: NASA-CR-137697 , HST-TR-344-0
    Format: application/pdf
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  • 100
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    Transonic aerodynamic characteristics of the 10-percent-thick NASA supercritical airfoil 31 (1975)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Refinements in a 10 percent thick supercritical airfoil (airfoil 31) have produced significant improvements in the drag characteristics compared with those for an earlier supercritical airfoil (airfoil 12) designed for the same normal force coefficient of 0.7. Drag creep was practically eliminated at normal force coefficients between about 0.4 and 0.7 and was greatly reduced at other normal force coefficients. Substantial reductions in the drag levels preceding drag divergence were also achieved at all normal force coefficients. The Mach numbers at which drag diverges were delayed for airfoil 31 at normal force coefficients up to about 0.6 (by approximately 0.01 and 0.02 at normal force coefficients of 0.4 and 0.6, respectively) but drag divergence occurred at slightly lower Mach numbers at higher normal force coefficients.
    Keywords: AERODYNAMICS
    Type: NASA-TM-X-3203 , L-9841 , NAS 1.15:X-3203
    Format: application/pdf
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    NASA TECHNICAL REPORTS
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