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  • AERODYNAMICS  (3,109)
  • STRUCTURAL MECHANICS  (3,031)
  • 1975-1979  (3,153)
  • 1965-1969  (2,987)
Collection
Keywords
Years
Year
  • 1
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    Combined vibration/temperature/sideload environmental testing of UHF blade antennas (1979)
    In:  CASI
    Details
    Publication Date: 2006-07-02
    Description: Service problems encountered on the F-4 aircraft showed that the environmental qualification requirements for the UHF blade antenna were not adequate. Although the individual environmental levels were stringent enough, only combined environmental testing could duplicate the conditions in which service problems occurred. Techniques for applying static side load simultaneously with vibration and temperature were developed. The combined environment testing was instrumental in the rapid assessment of antenna modifications and resulted in a final configuration which proved satisfactory in service. A need to include combined environmental testing for qualification of blade antennas was established.
    Keywords: STRUCTURAL MECHANICS
    Type: Shock and Vibration Inform. Center The Shock and Vibration Bull., Pt. 3; p 79-84
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  • 2
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    Executive summary of Aircraft Icing Specialists Workshop (1979)
    In:  CASI
    Details
    Publication Date: 2006-01-12
    Description: In a period of escalating development costs for new aircraft, there is growing interest in a renewed and coordinated icing research effort to achieve an updating or modernization of each aspect of the technological issues that are involved. This includes the data base, analysis methods, test techniques, and test facilities.
    Keywords: AERODYNAMICS
    Type: Aircraft Icing; p 1-16
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  • 3
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    A simplified method of evaluating the stress wave environment of internal equipment (1979)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: A simplified method called the transfer function technique (TFT) was devised for evaluating the stress wave environment in a structure containing internal equipment. The TFT consists of following the initial in-plane stress wave that propagates through a structure subjected to a dynamic load and characterizing how the wave is altered as it is transmitted through intersections of structural members. As a basis for evaluating the TFT, impact experiments and detailed stress wave analyses were performed for structures with two or three, or more members. Transfer functions that relate the wave transmitted through an intersection to the incident wave were deduced from the predicted wave response. By sequentially applying these transfer functions to a structure with several intersections, it was found that the environment produced by the initial stress wave propagating through the structure can be approximated well. The TFT can be used as a design tool or as an analytical tool to determine whether a more detailed wave analysis is warranted.
    Keywords: STRUCTURAL MECHANICS
    Type: Shock and Vibration Inform. Center The Shock and Vibration Bull., Pt. 1; p 89-96
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  • 4
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    High G pyrotechnic shock simulation using metal-to-metal impact (1979)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: A technique for simulating high g level pyrotechnic shocks is described and the results of applying the technique to obtain the MIL-STD-1540A shock spectrum with a maximum acceleration of 18,000g at 2,000 Hz are presented. Designing the resonant beam and plate on which the test unit is mounted, and generating a proper impulsive load on them, were the essentials of the technique. One dimensional stress wave and Euler equations were employed in the design. A metal pendulum hammer was used to generate the impulsive load.
    Keywords: STRUCTURAL MECHANICS
    Type: Shock and Vibration Inform. Center The Shock and Vibration Bull., Pt. 1; p 97-100
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  • 5
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    Probability of failure prediction for step-stress fatigue under sine or random stress (1979)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: A previously proposed cumulative fatigue damage law is extended to predict the probability of failure or fatigue life for structural materials with S-N fatigue curves represented as a scatterband of failure points. The proposed law applies to structures subjected to sinusoidal or random stresses and includes the effect of initial crack (i.e., flaw) sizes. The corrected cycle ratio damage function is shown to have physical significance.
    Keywords: STRUCTURAL MECHANICS
    Type: Shock and Vibration Inform. Center The Shock and Vibration Bull., Pt. 1; p 31-41
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  • 6
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    Safety hazard of aircraft icing (1979)
    In:  CASI
    Details
    Publication Date: 2006-01-12
    Description: The problem of aircraft icing is reported as well as the type of aircraft affected, the pilots involved, and an identification of the areas where reduction in icing accidents are readily accomplished.
    Keywords: AERODYNAMICS
    Type: NASA. Lewis Res. Center Aircraft Icing; p 21-27
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  • 7
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    Civil Helicopter icing problems (1979)
    In:  CASI
    Details
    Publication Date: 2006-01-12
    Description: The ice capabilities of rotary wing aircraft are examined. Recommendations are given to improve the inadequacies of the weather forecasts pertaining to ice, and to adopt a low maintenance anti-ice system.
    Keywords: AERODYNAMICS
    Type: NASA. Lewis Res. Center Aircraft Icing; p 29-30
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  • 8
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    Overview of helicopter ice protection system developments (1979)
    In:  CASI
    Details
    Publication Date: 2006-01-12
    Description: Helicopter ice protection design criteria was developed and technological shortcoming in meeting helicopter mission requirements is that of helicopter rotor blade ice protection. Airframe components are protected using existing technology while the rotor blade protected using the cyclic electrothermal deicing concept.
    Keywords: AERODYNAMICS
    Type: NASA. Lewis Res. Center Aircraft Icing; p 39-65
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  • 9
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    A review of the icing situation from the standpoint of general aviation (1979)
    In:  CASI
    Details
    Publication Date: 2006-01-12
    Description: An overview of the present situation in the field of aircraft icing with respect to certification and operation of nontransport category airplanes is given. Problems of definition and inconsistencies are pointed out. Problems in the forecasting and measurement of icing intensities are discussed. The present regulatory environment is examined with respect to its applicability and appropriateness to nontransport airplanes.
    Keywords: AERODYNAMICS
    Type: NASA. Lewis Res. Center Aircraft Icing; p 31-38
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  • 10
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    Icing of aircraft Some remarks with an historical slant from a cloud physicist (1979)
    In:  CASI
    Details
    Publication Date: 2006-01-12
    Description: Three areas of interest are commented on: cloud physics, nowcasting, and instrumentation. A comparison is made of what was done 30 years ago to what might be done in light of developments in related areas of cloud physics, weather modification and instrumentation.
    Keywords: AERODYNAMICS
    Type: NASA. Lewis Res. Center Aircraft Icing; p 17-19
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  • 11
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    Mechanics of fracture - Fundamentals and some recent developments (1979)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: An overview is presented of the fundamental aspects of and recent developments in fracture mechanics. Reference is made to linear elastic fracture mechanics including the state of stresses and displacements in the vicinity of cracks, effects of crack geometry and orientation on stress intensity factors, energy balance of Griffith, Irwin's stress intensity concept, and linear elastic fracture mechanics testing for fracture toughness. Other aspects of this paper include the non-linear behavior of materials and their influence on fracture mechanics parameters, consideration of viscoelasticity and plasticity, non-linear fracture toughness parameters as C.O.D., R-curve and J-integral, and a non-linear energy method, proposed by Liebowitz. Finite element methods applied to fracture mechanics problems are indicated. Also, consideration has been given to slow crack growth, dynamic effects on K(IC), Sih's criterion for fracture, Lee and Liebowitz's criterion relating crack growth with plastic energy, and applications of fracture mechanics to aircraft design. Suggestions are offered for future research efforts to be undertaken in fracture mechanics.
    Keywords: STRUCTURAL MECHANICS
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  • 12
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    NASA-Langley Research Center's participation in a round-robin comparison between some current crack-propagation prediction methods (1979)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A round-robin study was conducted which evaluated and compared different methods currently in practice for predicting crack growth in surface-cracked specimens. This report describes the prediction methods used by the Fracture Mechanics Engineering Section, at NASA-Langley Research Center, and presents a comparison between predicted crack growth and crack growth observed in laboratory experiments. For tests at higher stress levels, the correlation between predicted and experimentally determined crack growth was generally quite good. For tests at lower stress levels, the predicted number of cycles to reach a given crack length was consistently higher than the experimentally determined number of cycles. This consistent overestimation of the number of cycles could have resulted from a lack of definition of crack-growth data at low values of the stress intensity range. Generally, the predicted critical flaw sizes were smaller than the experimentally determined critical flaw sizes. This underestimation probably resulted from using plane-strain fracture toughness values to predict failure rather than the more appropriate values based on maximum load.
    Keywords: STRUCTURAL MECHANICS
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  • 13
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    A review and assessment of the stress-intensity factors for surface cracks (1979)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The stress-intensity factor solutions proposed for a surface crack in a finite plate subjected to uniform tension are reviewed. Fourteen different solutions obtained over the past 16 years using approximate analytical methods, experimental methods, and engineering estimates are compared. The accuracy of the various solutions is assessed by correlating fracture data on surface-cracked tension specimens made of a brittle epoxy material. Fracture of the epoxy material was characterized by a constant value of stress-intensity factor as failure. Thus, the correctness of various solutions is judged by the variations in the stress-intensity factors at failure. The solutions were ranked in order of minimum standard deviation. The highest ranking solutions correlated 95% of data analyzed within + or - 10% whereas the lowest ranking solutions correlated 95% of data analyzed within + or - 20%. Some solutions could be applied to all data considered, whereas others were limited with respect to crack shapes and crack sizes that could be analyzed.
    Keywords: STRUCTURAL MECHANICS
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  • 14
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    Numerical solution for perpendicular sonic hydrogen injection into a ducted supersonic airstream (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: This note discusses a computer program being developed to study the flow field near opposing perpendicular fuel injectors in scramjets. The MacCormack time-split, finite difference relaxation technique was used to solve the full two-dimensional compressible Navier-Stokes equations along with energy and species equations. By using this technique, a program was developed to consider the turbulent nonreacting flow of hydrogen and air in a rectangular duct. A damping term, proportional to the second derivative of pressure and temperature, was used to produce a stable solution behind the hydrogen jet in the neighborhood of the recompression shock. A case using actual conditions encountered in current scramjet design was analyzed, with results agreeing qualitatively with experimental observations.
    Keywords: AERODYNAMICS
    Type: AIAA Journal; 17; May 1979
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  • 15
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    Finite dynamic element formulation for a plane triangular element (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Higher order correction terms for the stiffness and inertia matrices associated with a triangular plane stress-strain finite dynamic element are developed in detail. Numerical results are presented which indicate that the adoption of these matrices along with a suitable quadratic matrix eigenproblem solver effects a significant economy in the free vibration solution of structure when compared with the analysis based on the usual finite element procedure. Finally, a FORTRAN IV computer program listing of the various relevant matrices is given.
    Keywords: STRUCTURAL MECHANICS
    Type: International Journal for Numerical Methods in Engineering; 14; 10, 1; 1979
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  • 16
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    Generalized velocities in the outer region of hypersonic turbulent boundary layers (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: An attempt is made to show that the outer portion of the velocity profile of hypersonic turbulent boundary layers can be transformed so that the constants determined by a best fit to the law of the wake are in reasonable agreement with the wake constant for incompressible boundary layers at the same Reynolds number. Both y transformations (where y is distance from the surface) and velocity transformations produce velocity profiles which, with the proper choice of wall shear stress to give shear velocity, can be reduced to the incompressible law of the wall.
    Keywords: AERODYNAMICS
    Type: AIAA Journal; 17; Aug. 197
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  • 17
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    Accurate numerical evaluation of modified Struve functions occurring in unsteady aerodynamics (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: A method is developed for computing the modified Struve functions that occur in unsteady aerodynamics. The method uses a rational approximation supplemented by an asymptotic series for large argument. Simple recursive formulas for generating the coefficients are derived. The method is capable of generating results of arbitrary accuracy. It can also be used for complex argument and order. For greater computing speed, a method is presented that uses the rational and asymptotic approximations to generate Chebyshev coefficients.
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft; 16; July 197
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  • 18
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    Analysis of beam-like lattice trusses (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: A simple procedure is presented for predicting the thermoelastic and free vibration responses of large repetitive beam-like trusses. The procedure is based on replacing the original lattice structure by an equivalent continuum beam model and obtaining closed-form (exact) solutions for the beam model. The equivalent beam model accounts for warping and shear deformation in the plane of the cross-section and is characterized by its thermoelastic strain and kinetic energies, from which the equations of motion and constitutive relations can be derived. The high accuracy of the results obtained by the proposed approach is demonstrated by means of numerical examples.
    Keywords: STRUCTURAL MECHANICS
    Type: Computer Methods in Applied Mechanics and Engineering; 20; Oct. 197
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  • 19
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    Laminar and turbulent flows over a spherically blunted cone with massive surface blowing (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Numerical solutions are presented for the flow over a spherically blunted cone with massive surface blowing. Time-dependent viscous shock layer equations are used to describe the flowfield. The boundary conditions on the body surface include a prescribed blowing rate distribution. The governing equations are solved by a time-asymptotic finite-difference method. Results presented here are only for a perfect gas-type flow at zero angle of attack. Both laminar and turbulent flow solutions are obtained. It is found that the surface blowing smooths out the effect of the curvature discontinuity at the sphere-cone juncture point on the laminar flowfield and results in a negative pressure gradient over the body. The shock slope increases on the downstream portion of the body as the surface blowing rate is increased. The turbulent flow with surface blowing is found to redevelop a boundary-layer-like region near the surface. The effects of this boundary-layer-like region on the flowfield and heating rates are discussed.
    Keywords: AERODYNAMICS
    Type: AIAA Journal; 17; Dec. 197
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  • 20
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    Some observations regarding the statistical determination of stress rupture regression lines (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Observations concerning the statistical evaluation of creep data are presented. Methods currently employed in the determination of stress rupture regression lines can result in conflicting and necessarily invalid results. Anomalous behavior is principally associated with the selection of the dependent variable. However, it is the least squares method of curve fitting which introduces regression bias. Methods to improve the validity of least squares regressions are suggested.
    Keywords: STRUCTURAL MECHANICS
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  • 21
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    Buckling of rotating beams (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: The stability of a beam subjected to compressive centrifugal forces arising from steady rotation about an axis which does not pass through the clamped end of the beam is analyzed to determine the critical rotational speeds for buckling in the inplane and out-of-plane directions. The differential equations of motion are solved numerically using an integrating matrix method in combination with an eigenanalysis to determine the eigenvalues from which stability is assessed. The results clarify several differences which have been identified in the literature relating to the proper behavior of the critical rotational speed for buckling as the radius of rotation of the clamped end of the beam is reduced.
    Keywords: STRUCTURAL MECHANICS
    Type: International Journal of Mechanical Sciences; 21; 12, 1; 1979
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  • 22
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    Simple spline-function equations for fracture mechanics calculations (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: The paper presents simple spline-function equations for fracture mechanics calculations. A spline function is a sequence of piecewise polynomials of degree n greater than 1 whose coefficients are such that the function and its first n-1 derivatives are continuous. Second-degree spline equations are presented for the compact, three point bend, and crack-line wedge-loaded specimens. Some expressions can be used directly, so that for a cyclic crack propagation test using a compact specimen, the equation given allows the cracklength to be calculated from the slope of the load-displacement curve. For an R-curve test, equations allow the crack length and stress intensity factor to be calculated from the displacement and the displacement ratio.
    Keywords: STRUCTURAL MECHANICS
    Type: International Journal of Fracture; 15; Oct. 197
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  • 23
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    A quarter-century of progress in the development of correlation and extrapolation methods for creep rupture data (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Developments in the analysis of creep-rupture data are reviewed with particular reference to time temperature relations for the correlation and extrapolation of creep and stress rupture data, the minimum commitment method, and successive regression methods. Some contributions to the development of time-temperature parameters are noted.
    Keywords: STRUCTURAL MECHANICS
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  • 24
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    Wave propagation in transversely impacted composite laminates (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: An experimental study was conducted to determine the wave-propagation characteristics, transient strains and residual properties of unidirectional and angle-ply boron/epoxy and graphite/epoxy laminates impacted with silicon-rubber projectiles at velocities up to 250 m/sec. Results include the following: (1) the predominant wave is the flexural wave propagating at different velocities in different directions; (2) peak strains and strain rates in the transverse to the (outer) fiber direction are much higher than those in the direction of the fibers; (3) strain rates up to 640/sec were measured; and (4) unidirectional laminates under impact showed appreciable modulus and strength degradation in the direction transverse to fibers.
    Keywords: STRUCTURAL MECHANICS
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  • 25
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    Fast, conservative schemes for the full potential equation applied to transonic flows (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Implicit approximate factorization techniques (AF) are investigated for the solution of matrix equations resulting from finite-difference approximations to the full potential equation in conservation form. For transonic flows, an artificial viscosity, required to maintain stability in supersonic regions, is introduced by an upwind bias of the density. Two implicit AF procedures are presented, and their convergence performance is compared with that of the standard transonic solution procedure: successive line overrelaxation (SLOR). Subcritical and supercritical test cases are considered. Results indicate a substantial improvement in convergence rate for AF schemes relative to SLOR.
    Keywords: AERODYNAMICS
    Type: AIAA Journal; 17; Feb. 197
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  • 26
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    Analysis of misalignment in the tension test (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Many experimenters fail to appreciate the significance of test system alignment during a tensile test. Poor alignment can increase data scatter and significantly influence some of the test results. In this paper a comprehensive analytical study of the misalignment problem in the plastic strain range is presented and errors caused by misalignment estimated. The results show that the stress-strain curve is not significantly affected by misalignment. However, the strains at the outermost fibers of the specimen cross-section are strongly affected by misalignment. Therefore, the effect of misalignment is most important when properties sensitive to local strain concentrations are being investigated.
    Keywords: STRUCTURAL MECHANICS
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  • 27
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    Criteria for asymptotic supersonic two-dimensional turbulent wakes (1979)
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    Publication Date: 2011-08-17
    Description: Indicators used to determine the fully developed mean flow for two dimensional turbulent supersonic wakes are examined. The similarity variables for velocity temperature and the transverse coordinate used by Demetriades (1969) and Wagner (1972) are shown not to adequately distinguish transition from developed turbulent flows. The growth rate of the two dimensional turbulent wake as the wake develops from laminar to turbulent are shown to be low in the laminar region, increase at transition, and level off as fully developed turbulence is attained, demonstrating that wake growth rates are better indicators of a fully developed mean flow than are similarity variables.
    Keywords: AERODYNAMICS
    Type: AIAA Journal; 17; July 197
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  • 28
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    Quasi-periodic structure of a turbulent jet (1979)
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    Publication Date: 2011-08-17
    Description: The instantaneous near field pressure fluctuations of an axisymmetric subsonic jet were measured by using a longitudinal and an azimuthal microphone arrays in order to qualitatively determine the behaviors of the quasi-periodic structure within the flow. Statistical analysis is used to explain the characteristic of the pressure signals. In addition to the information obtained by forming the power spectral density, auto- and cross-correlation functions, two types of signals are extracted through a conditional probability analysis to represent the quasi-periodic and the random fine structures within the turbulent jet. The quasi-periodic structure first appears as a rolling up of the mixing layer flow within one nozzle diameter downstream of the exit, then becomes fully developed at approximately 3 nozzle diameters downstream with a preferred Strouhal number range 0.3-0.4, and finally disappears beyond the end of potential core. This behavior is also reflected in the variation of the convection velocity.
    Keywords: AERODYNAMICS
    Type: Journal of Sound and Vibration; 64; May 8
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  • 29
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    Non-linear dynamic response of a wind turbine blade (1979)
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    Publication Date: 2011-08-17
    Description: The paper outlines the nonlinear dynamic analysis of an isolated three-degree flap-lag-feather wind turbine blade under a gravity field and with shear flow. Lagrangian equations are used to derive the nonlinear equations of motion of blade for arbitrarily large angular deflections. The limit cycle analysis for forced oscillations and the determination of the principal parametric resonance of the blade due to periodic forces from the gravity field and wind shear are performed using the harmonic balance method. Results are obtained first for a two-degree flap-lag blade, then the effect of the third degree of freedom (feather) is studied. The self-excited flutter solutions are obtained for a uniform wind and with gravity forces neglected. The effects of several parameters on the blade stability are examined, including coning angle, structural damping, Lock number, and feather frequency. The limit cycle flutter solution of a typical configuration shows a substantial nonlinear softening spring behavior.
    Keywords: STRUCTURAL MECHANICS
    Type: Journal of Sound and Vibration; 63; Mar. 22
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  • 30
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    Recent finite element studies in plasticity and fracture mechanics (1979)
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    Publication Date: 2011-08-17
    Description: The paper reviews recent work on fundamentals of elastic-plastic finite-element analysis and its applications to the mechanics of crack opening and growth in ductile solids. The presentation begins with a precise formulation of incremental equilibrium equations and their finite-element forms in a manner valid for deformations of arbitrary magnitude. Special features of computational procedures are outlined for accuracy in view of the near-incompressibility of elastic-plastic response. Applications to crack mechanics include the analysis of large plastic deformations at a progressively opening crack tip, the determination of J integral values and of limitations to J characterizations of the intensity of the crack tip field, and the determination of crack tip fields in stable crack growth.
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  • 31
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    Reynolds number effects on the turbulence field in compressible boundary layers (1979)
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    Publication Date: 2011-08-17
    Description: Detailed experiments were conducted in a zero pressure gradient, supersonic turbulent boundary layer, including measurements of the three components of velocity fluctuations and the turbulent shear stress, for Reynolds numbers ranging from 11.7 million to 105 million at a freestream Mach number of 2.3. The mean flow measurements established the fully developed and equilibrium nature of the boundary layer. Measurements of the turbulence field show that the vertical and transverse fluctuations are essentially equal throughout the boundary layer at all Reynolds numbers, a feature that is different from observations in incompressible flows. The data show that the boundary layer exhibits similarity in the turbulence profiles for the entire Reynolds number range and agrees with previous compressible and incompressible data using Morkovin's scaling to account for compressibility effects.
    Keywords: AERODYNAMICS
    Type: AIAA Journal; 17; Apr. 197
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  • 32
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    Stress-intensity factors for a wide range of semi-elliptical surface cracks in finite-thickness plates (1979)
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    Publication Date: 2011-08-17
    Description: Surface cracks are among the more common flaws in aircraft and pressure vessel components. Several calculations of stress-intensity factors for semi-elliptical surface cracks subjected to tension have appeared in the literature. However, some of these solutions are in disagreement by 50-100%. In this paper, stress-intensity factors for shallow and deep semi-elliptical surface cracks in plates subjected to tension are presented. To verify the accuracy of the three-dimensional finite-element models employed, convergence was studied by varying the number of degrees of freedom in the models from 1500 to 6900. The 6900 degrees of freedom used here were more than twice the number used in previously reported solutions. Also, the stress-intensity variations in the boundary-layer region at the intersection of the crack with the free surface were investigated.
    Keywords: STRUCTURAL MECHANICS
    Type: Engineering Fracture Mechanics; 11; 4, 19; 1979
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  • 33
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    Some steady and oscillating airfoil test results, including the effects of sweep, from the tunnel spanning wing (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: A large scale tunnel spanning wing was built and tested. The model can be operated as either a swept or unswept wing and can be tested in steady state or oscillated sinusoidally in pitch about its quarter chord. Data is taken at mid-span with an internal 6-component balance and is also obtained from miniature pressure transducers distributed near the center span region. A description is given of the system and a brief discussion of some of the steady and unsteady results obtained to date. These are the steady load behavior to Mach numbers of approximately 1.1 and unsteady loads, including drag, at a reduced frequency of approximately 0.1.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Res. Center Advanced Technol. Airfoil Res., Vol. 1, Pt. 1; p 445-458
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    A new airfoil research capability (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The design and construction of a self streamlining wall test section for the Langley 0.3 meter transonic cryogenic tunnel was included in the fiscal year 1978 construction of facilities budget for Langley Research Center. The design is based on the research being carried out by M. J. Goodyer at the University of Southampton, Southampton, England, and is supported by Langley Research Center. This paper presents a brief description of the project. Included are some of the design considerations, anticipated operational envelope, and sketches showing the detail design concepts. Some details of the proposed operational mode, safety aspects, and preliminary schedule are presented.
    Keywords: AERODYNAMICS
    Type: Advanced Technol. Airfoil Res., Vol. 1, Pt. 1; p 425-432
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  • 35
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    Design and calibration of slotted walls for transonic airfoil wind tunnels (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The traditional procedure for estimating the performance of slotted walls for airfoil wind tunnels is reviewed, and a modification which improves the accuracy of this procedure is described. Unlike the traditional procedure, the modified procedure indicates that the design of airfoil wind-tunnel walls which induce minimal blockage and streamline-curvature effects is feasible. The design and testing of such a slotted wall is described. It is shown experimentally that the presence of a model can affect the plenum pressure and thus make the use of the plenum pressure as a calibration reference questionable. Finally, an ONERA experiment which shows the effect of the sidewall boundary layer on the measured model normal force is discussed.
    Keywords: AERODYNAMICS
    Type: Advanced Technol. Airfoil Res., Vol. 1, Pt. 1; p 433-443
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  • 36
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    Inverse boundary-layer technique for airfoil design (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: A description is presented of a technique for the optimization of airfoil pressure distributions using an interactive inverse boundary-layer program. This program allows the user to determine quickly a near-optimum subsonic pressure distribution which meets his requirements for lift, drag, and pitching moment at the desired flow conditions. The method employs an inverse turbulent boundary-layer scheme for definition of the turbulent recovery portion of the pressure distribution. Two levels of pressure-distribution architecture are used - a simple roof top for preliminary studies and a more complex four-region architecture for a more refined design. A technique is employed to avoid the specification of pressure distributions which result in unrealistic airfoils, that is, those with negative thickness. The program allows rapid evaluation of a designed pressure distribution off-design in Reynolds number, transition location, and angle of attack, and will compute an airfoil contour for the designed pressure distribution using linear theory.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Res. Center Advanced Technol. Airfoil Res., Vol. 1, Pt. 1; p 383-397
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  • 37
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    Langley's two-dimensional research facilities: Capabilities and plans (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The current capabilities and the forthcoming plans for Langley's two-dimensional research facilities are described. The characteristics of the Langley facilities are discussed in terms of Reynolds number, Mach number, and angle-of-attack capabilities. Comments are made with regard to the approaches which have been investigated to alleviate typical problem areas such as wall boundary effects. Because of the need for increased Reynolds number capability at high subsonic speeds, a considerable portion of the paper deals with a description of the 20 by 60 cm two-dimensional test section of the Langley 0.3 meter transonic cryogenic tunnel which is currently in the calibration and shakedown phase.
    Keywords: AERODYNAMICS
    Type: Advanced Technol. Airfoil Res., Vol. 1, Pt. 1; p 399-414
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  • 38
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    The prediction of two-dimensional airfoil stall progression (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: A generalized boundary condition potential flow calculation method was combined with a momentum integral boundary layer method and a base flow theory of separation to predict airfoil viscous-inviscid interference up to and beyond stall. The resultant program considers laminar and turbulent separation and is, therefore, applicable to thin or thick airfoil stall. The calculated flow field includes the airfoil and the separation bubble recombination region behind the airfoil. Calculated pressure distributions and equivalent airfoil shapes, including the displacement thickness of the viscous regions, are compared with flow field measurements for several airfoils. The measured displacement thicknesses and wake centerlines corroborate the calculated shape. The comparison also suggests the use of the analytical solution to evaluate the measurements.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Res. Center Advanced Technol. Airfoil Res., Vol. 1, Pt. 1; p 335-345
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  • 39
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    Application of numerical optimization to the design of advanced supercritical airfoils (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: An application of numerical optimization to the design of advanced airfoils for transonic aircraft showed that low-drag sections can be developed for a given design Mach number without an accompanying drag increase at lower Mach numbers. This is achieved by imposing a constraint on the drag coefficient at an off-design Mach number while minimizing the drag coefficient at the design Mach number. This multiple design-point numerical optimization has been implemented with the use of airfoil shape functions which permit a wide range of attainable profiles during the optimization process. Analytical data for the starting airfoil shape, a single design-point optimized shape, and a double design-point optimized shape are presented. Experimental data obtained in the NASA Ames two-by two-foot wind tunnel are also presented and discussed.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Res. Center Advanced Technol. Airfoil Res., Vol. 1, Pt. 1; p 315-325
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  • 40
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    Improved prediction of laminar leading edge separation (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Research was conducted to provide a definite criterion for the prediction of the bubble burst on airfoils typical of those used for fighter wings. The approach taken was to correlate existing airfoil bubble burst data using various parameters at the laminar separation point. The method due to Weber was modified to provide a continuous analytic solution for the velocity distribution around the airfoil leading edge. Coupling the modified Weber method with the Stratford laminar separation prediction method leads to a universal chart giving the conditions at separation as a function of stagnation location and leading edge radius. Application of the combined method to available two-dimensional airfoil data resulted in an empirical criterion presenting the limiting local velocity gradient at separation as a function of the boundary layer momentum thickness at separation for bubble burst. The correlation leads as well to the qualitative explanation of two types of laminar stall: thin airfoil and leading edge. The validity of the correlation is demonstrated by predicting the lift coefficient and angle of attack for stall on airfoils with leading edge or trailing edge flaps.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Res. Center Advanced Technol. Airfoil Res., Vol. 1, Pt. 1; p 327-334
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  • 41
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    Optimization of multi-element airfoils for maximum lift (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Two theoretical methods are presented for optimizing multi-element airfoils to obtain maximum lift. The analyses assume that the shapes of the various high lift elements are fixed. The objective of the design procedures is then to determine the optimum location and/or deflection of the leading and trailing edge devices. The first analysis determines the optimum horizontal and vertical location and the deflection of a leading edge slat. The structure of the flow field is calculated by iteratively coupling potential flow and boundary layer analysis. This design procedure does not require that flow separation effects be modeled. The second analysis determines the slat and flap deflection required to maximize the lift of a three element airfoil. This approach requires that the effects of flow separation from one or more of the airfoil elements be taken into account. The theoretical results are in good agreement with results of a wind tunnel test used to corroborate the predicted optimum slat and flap positions.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Res. Center Advanced Technol. Airfoil Res., Vol. 1, Pt.1; p 237-253
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    Improvements in surface singularity analysis and design methods (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The coupling of the combined source vortex distribution of Green's potential flow function with contemporary numerical techniques is shown to provide accurate, efficient, and stable solutions to subsonic inviscid analysis and design problems for multi-element airfoils. The analysis problem is solved by direct calculation of the surface singularity distribution required to satisfy the flow tangency boundary condition. The design or inverse problem is solved by an iteration process. In this process, the geometry and the associated pressure distribution are iterated until the pressure distribution most nearly corresponding to the prescribed design distribution is obtained. Typically, five iteration cycles are required for convergence. A description of the analysis and design method is presented, along with supporting examples.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Res. Center Advanced Technol. Airfoil Res., Vol. 1, Pt. 1; p 221-236
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  • 43
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    Prospects for computing airfoil aerodynamics with Reynolds averaged Navier-Stokes codes (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The Reynolds averaged Navier-Stokes equations are solved numerically for a variety of transonic airfoil configurations where viscous phenomena are important. Illustrative examples include flows past sensitive geometries, Reynolds number effects, and buffet phenomena.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Res. Center Advanced Technol. Airfoil Res., Vol. 1, Pt. 1; p 119-131
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  • 44
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    Overview of two-dimensional airfoil research at Ames Research Center (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The five basic elements of the two dimensional airfoil research program at Ames Research Center are illustrated. These elements are experimental, theoretical (including computational), validation, design optimization, and industry interaction. Each area is briefly discussed.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Res. Center Advanced Technol. Airfoil Res., Vol. 1, Pt. 1; p 39-44
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  • 45
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    Low speed airfoil design and analysis (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: A low speed airfoil design and analysis program was developed which contains several unique features. In the design mode, the velocity distribution is not specified for one but many different angles of attack. Several iteration options are included which allow the trailing edge angle to be specified while other parameters are iterated. For airfoil analysis, a panel method is available which uses third-order panels having parabolic vorticity distributions. The flow condition is satisfied at the end points of the panels. Both sharp and blunt trailing edges can be analyzed. The integral boundary layer method with its laminar separation bubble analog, empirical transition criterion, and precise turbulent boundary layer equations compares very favorably with other methods, both integral and finite difference. Comparisons with experiment for several airfoils over a very wide Reynolds number range are discussed. Applications to high lift airfoil design are also demonstrated.
    Keywords: AERODYNAMICS
    Type: Advanced Technol. Airfoil Res., Vol. 1, Pt. 1; p 73-100
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  • 46
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    Langley airfoil-research program (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: An overview of past, present, and future airfoil research activities at the Langley Research Center is given. The immediate past and future occupy most of the discussion; however, past accomplishments and milestones going back to the early NACA years are dealt with in a broad-brush way to give a better perspective of current developments and programs. In addition to the historical perspective, a short description of the facilities which are now being used in the airfoil program is given. This is followed by a discussion of airfoil developments, advances in airfoil design and analysis tools (mostly those that have taken place over the past 5 or 6 years), and tunnel-wall-interference predictive methods and measurements. Future research requirements are treated.
    Keywords: AERODYNAMICS
    Type: Advanced Technol. Airfoil Res., Vol. 1, Pt. 1; p 11-38
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  • 47
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    Prediction of aerodynamic characteristics for slender bodies alone and with lifting surfaces to high angles of attack (1979)
    In:  CASI
    Details
    Publication Date: 2017-10-02
    Description: A method is presented for computing normal force and pitching moment coefficients for slender bodies of circular and noncircular cross section alone and with lifting surfaces. A semiempirical term representing viscous-separation crossflow is added to a term representing potential-theory crossflow. For bodies of revolution, computed aerodynamic characteristics agree with measured results for investigated free-stream Mach numbers from 0.6 to 2.9 and for angles of attack from 0 deg to 180 deg. For bodies of elliptic cross section, measured results are predicted well over the investigated Mach number range from 0.6 to 2.0 and the angle range from 0 deg to 60 deg. For all bodies the predictions are best at supersonic Mach numbers. For body-wing and body-wing-tail configurations, measured normal force coefficients and centers are predicted at the upper test Mach number of 2.0. As the Mach number is decreased to 0.6, the agreement for the normal-force coefficients rapidly deteriorates. When model flow-separation and vortex patterns are asymmetric, undesirable side forces are usually measured on the models at subsonic Mach numbers and zero sideslip angle. Generally, the side-force coefficients decrease or vanish with: increase in Mach number, decrease in nose fineness ratio, nose blunting, and flattening of body cross section.
    Keywords: AERODYNAMICS
    Type: AGARD High Angle of Attack Aerodyn.; 40 p
    Format: text
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    Recent theoretical developments and experimental studies pertinent to vortex flow aerodynamics, with a view towards design (1979)
    In:  CASI
    Details
    Publication Date: 2017-10-02
    Description: Recent progress in a research program directed toward an improved vortex flow technology base was reviewed. Analysis methods for conical flow and analysis and design methods for nonconical flows are presented. Applications are made for a variety of planar, nonplanar, and interferring lifting surfaces. Several methods are shown to provide reasonable estimates of over-all forces and moments for simple wing planforms with the suction analogy method currently offering the most versatility for arbitrary configuration applications. For the prediction of surface loadings the free vortex sheet method being developed by Boeing is shown to have considerable promise and further development of this type of method is encouraged. A data base for ogee strake-wing configurations is summarized with an emphasis on the requirements for maximizing the interference lift. A strake planform design procedure is discussed and a first solution (gothic in planview) is integrated with a wing body. The data show the strake to exhibit expected stable vortex characteristics. It was found that, apart from increasing sweep, conically cambered delta wings developed drag levels approaching that of attached flow with increasing either the lift or the wing camber height, lastly, an approximate vortex flow design method, based on the suction analogy, is outlined and an example is given.
    Keywords: AERODYNAMICS
    Type: AGARD High Angle of Attack Aerodyn.; 31 p
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  • 49
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    The Mechanism of Fluid Resistance (1979)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: The mechanism of fluid resistance within the limit of the square law is presented. It was concluded that the investigations should be extended and completed in two directions, namely: by an investigation of stable vortex configurations in space, and by considering the perfect fluid as the limiting case of a viscous fluid and then limiting the law of vortex of formation with the condition that only those fluid particles which were in contact with the surface of the body can receive rotation.
    Keywords: AERODYNAMICS
    Type: NASA. Ames Res. Center Classical Aerodyn. Theory; p 57-66
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  • 50
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    Considerations of some critical ejector problems (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Some aspects of ejector design and application, including, three dimensional effects and cross flow effects are presented.
    Keywords: AERODYNAMICS
    Type: NASA. Ames Res. Center Workshop on Thrust Augmenting Ejectors; p 363-384
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  • 51
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    Large-scale turbulent structures in jets and in flows over cavities and their relationship to entrainment and mixing (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Large scale structures in jets and in flows over cavities were investigated experimentally to determine their role in entrainment, mixing, and noise production. The presence of these structures resulted in growth of the shear layer and entrainment. Merging of adjacent large scale structures caused the near field pressure signal in excited flows. It is believed that both the entrained fluid as well as its eventual mixing with the jet flow can be controlled by introducing pulsation in the jet flow at a frequency for which the flow is most unstable.
    Keywords: AERODYNAMICS
    Type: NASA. Ames Res. Center Workshop on Thrust Augmenting Ejectors; p 295-309
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  • 52
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    Recent developments in ejector technology in the Air Force: An overview (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Basic and applied studies in thrust augmentation conducted at the Aerospace Research Laboratory at Wright-Patterson AFB which led to an effective configuration of the jet flap diffuser ejector, are reviewed. A method for compressible ejector flow analysis, developed in support of the preliminary design of an ejector thrust aircraft, is discussed and applied to single- and two-stage ejectors.
    Keywords: AERODYNAMICS
    Type: NASA. Ames Res. Center Workshop on Thrust Augmenting Ejectors; p 1-22
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    A Comparison of the Aerodynamic Characteristics of Eight Sailwing Airfoil Sections (1979)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: The operational characteristics of sailwings are discussed with emphasis placed on the importance of the trailing edge cable tension. The three dimensional aerodynamic characteristics were obtained from wind tunnel tests, and the results compared to determine the magnitude of the aerodynamic penalties paid for various structural simplifications. For the sectional thickness ratios, it is concluded that, while the basic double-membraned sailwing has exceptional aerodynamic performance, even superior for some applications to the conventional hardwing, any notable deviation from this configuration results in an unacceptably large performance penalty.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Res. Center The Sci. and Technol. of Low Speed and Motorless Flight, Pt. 1; p 155-176
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  • 54
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    Low-speed single-element airfoil synthesis (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The use of recently developed airfoil analysis/design computational tools to clarify, enrich and extend the existing experimental data base on low-speed, single element airfoils is demonstrated. A discussion of the problem of tailoring an airfoil for a specific application at its appropriate Reynolds number is presented. This problem is approached by use of inverse (or synthesis) techniques, wherein a desirable set of boundary layer characteristics, performance objectives, and constraints are specified, which then leads to derivation of a corresponding viscous flow pressure distribution. Examples are presented which demonstrate the synthesis approach, following presentation of some historical information and background data which motivate the basic synthesis process.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Res. Center The Sci. and Technol. of Low Speed and Motorless Flight, Pt. 1; p 1-31
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    Space Shuttle Orbiter AFT heat shield seal (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The evolution of the orbiter aft heat shield seal (AHSS) design, which involved advancing mechanical seal technology in severe thermal environment is discussed. The baseline design, various improvements for engine access, and technical problem solution are presented. It is a structure and mechanism at the three main propulsion system (MPS) engine interfaces to the aft compartment structure. Access to each MPS engine requires disassembly and removal of the AHSS. Each AHSS accommodates the engine movement, is exposed to an extremely high temperature environment, and is part of the venting control of the aft compartment.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Johnson Space Center The 13th Aerospace Mech. Symp.; p 251-259
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    Hydrazine monopropellant reciprocating engine development (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: A hydrazine fueled piston engine for providing 11.2 kW was developed to satisfy the need for an efficient power supply in the range from 3.7 to 74.6 kW where existing nonair-breathing power supplies such as fuel cells or turbines are inappropriate. The engine was developed for an aircraft to fly to 21.3 km and above and cruise for extended periods. A remotely piloted aircraft and the associated flight control techniques for this application were designed. The engine is geared down internally (2:1) to accommodate a 1.8 m diameter propeller. An alternator is included to provide electrical power. The pusher-type engine is mounted onto the aft closure of the fuel tank, which also provides mounting for all other propulsion equipment. About 20 hrs of run time demonstrated good efficiency and adequate life. One flight test to 6.1 km was made using the engine with a small fixed-pitch four-bladed propeller. The test was successful in demonstrating operational characteristics and future potential.
    Keywords: STRUCTURAL MECHANICS
    Type: The 13th Aerospace Mech. Symp.; p 1-14
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    Summary of the Orbiter mechanical systems (1979)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: Major mechanical systems of the Orbiter space vehicle are summarized with respect to general design details, manner of operation, expected performance, and, where applicable, unique features. A synopsis of data obtained during the five atmospheric flight tests of spacecraft OV-101 and status of the systems for the first orbital spacecraft STS-1 are presented.
    Keywords: STRUCTURAL MECHANICS
    Type: The 13th Aerospace Mech. Symp.; p 219-234
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    The external augmentor concept for V/STOL aircraft (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The beneficial aspects of an ejector powered V/STOL concept were reviewed. The feasibility of satisfactorily incorporating an ejector system in a high performance V/STOL aircraft was investigated. The external augmentor concept, based on the use of chordwise ejector slots, is presented. It is concluded that the external augmentor concept has a basic inherent simplicity and a sufficient augmentor performance potential to make feasible a high performance V/STOL aircraft based on ejectors.
    Keywords: AERODYNAMICS
    Type: NASA. Ames Res. Center Workshop on Thrust Augmenting Ejectors; p 449-471
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    Interface concerns of ejector integration in V/STOL aircraft (1979)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: A number of areas which have in the past contributed to weight, complexity, and thrust losses in the ejector-powered V/STOL vehicle were identified. Most of these interfaces taken singly do not represent a severe compromise to the vehicle; however, the bottom line is that the sum of compromises and the subsequent effects on performance, flight operations and maintenance have rendered the ejector V/STOL aircraft unattractive. In addition to some of the unique ejector/aircraft integration problems, the vehicle by virtue of having a V/STOL capability, is compromised in other areas. To be successful and acceptable, the advantages must outweight the disadvantages and simplicity with minimum penalties must be the rule. It is concluded that more emphasis must be placed on the ejector/aircraft interface for the concept to be successful.
    Keywords: AERODYNAMICS
    Type: NASA. Ames Res. Center Workshop on Thrust Augmenting Ejectors; p 397-415
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    Entrainment characteristics of unsteady subsonic jets (1979)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: The effectiveness of jet unsteadiness in enhancing flow entrainment was assessed. It was conducted that entrainment depends on the type and amount of jet unsteadiness. Apparently, the mere introduction of jet unsteadiness by small sinusoidal flow angle variations is insufficient to enhance entrainment but, it should be noted that the results were obtained at measuring stations which are all many nozzle widths downstream of the jet nozzle. Thus, no fully conclusive statement can be made at this time about the entrainment close to the nozzle. The high entrainment of the fluidically oscillated jet was caused by the high-frequency content of this square wave type of oscillation but more detailed measurements are clearly needed, in particular for the fluidically oscillated and the pulsed jets. Practical ejector application requires the proper trade-off between entrainment and primary nozzle thrust efficiency.
    Keywords: AERODYNAMICS
    Type: NASA. Ames Res. Center Workshop on Thrust Augmenting Ejectors; p 311-324
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    Some tests on small-scale rectangular throat ejector (1979)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: A small scale rectangular throat ejector with plane slot nozzles and a fixed throat area was tested to determine the effects of diffuser sidewall length, diffuser area ratio, and sidewall nozzle position on thrust and mass augmentation. The thrust augmentation ratio varied from approximately 0.9 to 1.1. Although the ejector did not have good thrust augmentation performance, the effects of the parameters studied are believed to indicate probable trends in thrust augmenting ejectors.
    Keywords: AERODYNAMICS
    Type: NASA. Ames Res. Center Workshop on Thrust Augmenting Ejectors; p 239-251
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  • 62
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    Helical grip for the cable cars of San Francisco (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: A helical cable car grip to minimize high maintenance costs of San Francisco's cable car operation is presented. The grip establishes a rolling contact between the cable and grip to reduce sliding friction and associated cable wear. The design, development, and testing of the helical cable car grip are described.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Johnson Space Center The 13th Aerospace Mech. Symp.; p 83-93
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  • 63
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    An Exploratory Investigation of the Effect of Plastic Coating on the Profile Drag of a Practical-Metal-Construction Sailplane Airfoil (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: An exploratory investigation was performed in the Langley low-turbulence pressure tunnel to determine the effect of a plastic coating on the profile drage of a practical-metal-construction sailplaine airfoil. The mode was tested with three surface configurations: (1) filled, painted, and sanded smooth; (2) rough bare metal; and (3) plastic-coated. The investigation was conducted at Reynolds numbers based on airfoil chord of 1,100,000, 2,200,000, and 3,300,000 at a constant Mach number of 0.10. The results indicate that, at all three Reynolds numbers, the order of the drag values of the three surface configurations, starting with the highest drag, was: filled, painted, and sanded smooth; rough bare metal; and plastic-coated.
    Keywords: AERODYNAMICS
    Type: The Sci. and Technol. of Low Speed and Motorless Flight, Pt. 1; p 33-64
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  • 64
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    Space Shuttle Orbiter payload bay door mechanisms (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The opening, closing, and latching of the first large clamshell door to operate in space presented some unusual challenges for the mechanism designer of the Space Shuttle Program. The requirements, hardware configuration, design trade-offs, and qualification testing in process to meet the challenge and to make the system operational for the Shuttle orbiter's approaching first orbital flight are described.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Johnson Space Center The 13th Aerospace Mech. Symp.; p 261-269
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  • 65
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    Tests of a protective shell passive release mechanism for hypersonic wind-tunnel models (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: A protective shell mechanism for wind tunnel models was developed and tested. The mechanism is passive in operation, reliable, and imposes no new structural design changes for wind tunnel models. Methods of predicting the release time and the measured loads associated with the release of the shell are given. The mechanism was tested in a series of wind tunnel tests to validate the removal process and measure the pressure loads on the model. The protective shell can be used for wind tunnel models that require a step input of heating and loading such as a thin skin heat transfer model. The mechanism may have other potential applications.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Johnson Space Center The 13th Aerospace Mech. Symp.; p 167-181
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  • 66
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    Reliability breakthrough: An antenna deployment/positioning mechanism with electrical and mechanical redundancy (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: An Antenna Positioner Mechanism (APM) was developed for deployment of an antenna reflector and for fine granularity closed loop tracking of the antenna in response to RF beacon error signals. By utilizing permanent magnet stepper motors, spur gearheads, irreversible single threat worm/wheel assemblies and a miter gear differential, full electrical and mechanical redundancy was realized. Two versions of this design were generated: one is a weight-optimized design with a clutch for overload protection and one is a more rugged unit without a clutch.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Johnson Space Center The 13th Aerospace Mech. Symp.; p 137-149
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  • 67
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    Load proportional safety brake (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: This brake is a self-energizing mechanical friction brake and is intended for use in a rotary drive system. It incorporates a torque sensor which cuts power to the power unit on any overload condition. The brake is capable of driving against an opposing load or driving, paying-out, an aiding load in either direction of rotation. The brake also acts as a no-back device when torque is applied to the output shaft. The advantages of using this type of device are: (1) low frictional drag when driving; (2) smooth paying-out of an aiding load with no runaway danger; (3) energy absorption proportional to load; (4) no-back activates within a few degrees of output shaft rotation and resets automatically; and (5) built-in overload protection.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Johnson Space Center The 13th Aerospace Mech. Symp.; p 95-110
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  • 68
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    A two-axis pointing system for an orbiting astronomical instrument (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The system described was built for incorporation into a solar flare X-ray instrument due to be orbited as one of a number of instruments on the NASA Solar Maximum Mission (SMM) satellite in late 1979. It enables the instrument to be rotated about 2 mutually perpendicular axes in 5 arc-second steps within a range of 7 arc-minutes, thus giving the instrument the capability to map areas of the sun.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Johnson Space Center The 13th Aerospace Mech. Symp.; p 27-38
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  • 69
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    Automatic in-orbit assembly of large space structures (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The automated assembly of a large number of components required for the on-orbit erection of large tetrahedral space platforms is described. The assembly machine is a huge jig in which a multitude of mechanisms must operated continuously in the thermo vacuum environment of space and under the control of computers programmed to command every step of each motion. The concepts are presented to determine the most reliable solution. Continuous operation of mechanisms in space presents many unresolved problems, with regard to lubrication of unprotected devices, such as chain drives, which must maintain reasonable positioning tolerances.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Johnson Space Center The 13th Aerospace Mech. Symp.; p 283-291
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  • 70
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    IUSThrust Vector Control (TVC) servo system (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The IUS TVC SERVO SYSTEM which consists of four electrically redundant electromechanical actuators, four potentiometer assemblies, and two controllers to provide movable nozzle control on both IUS solid rocket motors is developed. An overview of the more severe IUS TVC servo system design requirements, the system and component designs, and test data acquired on a preliminary development unit is presented. Attention is focused on the unique methods of sensing movable nozzle position and providing for redundant position locks.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Johnson Space Center The 13th Aerospace Mech. Symp.; p 271-281
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  • 71
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    Payload installation and deployment aid for Space Shuttle Orbiter spacecraft remote manipulator system (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: An aid concept known as the PIDA (Payload Installation and Deployment Aid) is presented as a way to assist the RMS (Remote Manipulator System) by relaxing the accuracy required during payload handling in the payload bay. The aid concept was designed and developed to move payloads through a prescribed path between the confined quarters of the payload bay and a position outside the critical maneuvering area of the Orbiter. A description of the design requirements and the modes of operation of the various functions of the deployment and the docking mechanisms are covered.
    Keywords: STRUCTURAL MECHANICS
    Type: The 13th Aerospace Mech. Symp.; p 235-249
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  • 72
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    Magnetic spring in oscillating mirror linear scanner for satellite camera (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: One of the main difficulties encountered in the development of a multispectral scanner is the realization of an oscillating mechanical device. A magnetic device which is characterized by the absence of friction is presented. The main developments concern the analysis of magnetic forces. A preliminary project of a device which could be used in a satellite is presented.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Johnson Space Center The 13th Aerospace Mech. Symp.; p 183-193
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  • 73
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    A simple apparatus for the experimental study of non-steady flow thrust-augmenter ejector configurations (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: A flexible, and easily modified, test rig is described which allows a one dimensional nonsteady flow stream to be generated, economically from a steady flow source of compressed air. This nonsteady flow is used as the primary stream in a nonsteady flow ejector constituting part of the test equipment. Standard piezo-electric pressure transducers etc. allow local pressures to be studied, as functions of time, in both the primary and secondary (mixed) flow portions of the apparatus. Provision is also made for measuring the primary and secondary mass flows and the thrust generated. Sample results obtained with the equipment are presented.
    Keywords: AERODYNAMICS
    Type: NASA. Ames Res. Center Workshop on Thrust Augmenting Ejector; p 325-349
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  • 74
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    Nonsteady-Flow Thrust Augmenting Ejectors (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Ejector augmenters in which the transfer of mechanical energy from the primary to the secondary flow takes place through the work of interface pressure forces are investigated. Nonsteady flow processes are analyzed from the standpoint of energy transfer efficiency and a comparison of a rotary jet augmenter to an ejector is presented.
    Keywords: AERODYNAMICS
    Type: NASA. Ames Res. Center Workshop on Thrust Augmenting Ejectors; p 187-203
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  • 75
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    Numerical prediction of 3-D ejector flows (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The use of parametric flow analysis, rather than parametric scale testing, to support the design of an ejector system offers a number of potential advantages. The application of available 3-D flow analyses to the design ejectors can be subdivided into several key elements. These are numerics, turbulence modeling, data handling and display, and testing in support of analysis development. Experimental and predicted jet exhaust for the Boeing 727 aircraft are examined.
    Keywords: AERODYNAMICS
    Type: NASA. Ames Res. Center Workshop on Thrust Augmenting Ejectors; p 55-70
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  • 76
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    Unfolding the air vanes on a supersonic air-launched missile (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: ASALM (Advanced Strategic Air-Launched Missile) is a supersonic air vehicle designed to be air-launched from a carrier aircraft. The four aft aerodynamic control vanes are folded to maximize the number of missiles carried on-board. The unfolding (erection) system must be small, energetic, fast, and strong. The materials selected and problems that arose during development of the unfolding system are described.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Johnson Space Center The 13th Aerospace Mech. Symp.; p 207-217
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  • 77
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    On the design of an adjustable high precision latching hinge (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The design and test details of a high precision hinge and locking mechanism created principally in support of the Lockheed space deployable Flexrib Parabolic Antenna concept are presented. These developed improvements in the detail design of ultra-precise rib hinge and contour adjustment mechanisms will allow radio frequency antenna reflectors to expand into the 15-50 meter diameter size class and to support the .013 mm. deployment repeatability tolerance required to support the 12+ GHz frequency range.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Johnson Space Center The 13th Aerospace Mech. Symp.; p 127-136
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  • 78
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    A telescopic jib for continuous adjustment (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: For special space applications, e.g. for experiments distant from any orbital platforms or manipulators a new kind of jibs with extreme extension capacity has to be designed. Considering the requirements, the telescopic principle is found to be the most promising. For the choice of the stiff structure, design criteria are evaluated. Special effort deals with the drive system. An electromechanical system can satisfy the requirements. First results of the development of such a drive are presented. The most significant features are: A telescopic assembly of tubes which can be mutually moved by a short spindle in the center of the package. An elastically suspended screw is located at the bottom of each tube. For the jib extension, these screws will be linked with the spindle. The control of their sequence and the adjustment of tubes in mutual end positions are performed by latches. A functional model proved the basic idea.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Johnson Space Center The 13th Aerospace Mech. Symp.; p 49-58
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  • 79
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    Development of the Trident 1 aerodynamic saike mechanism (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The Aerospike drag reduction mechanism was designed and developed for use on the Trident I submarine launched ballistic missile. This mechanism encounters a unique combination of environments necessitating unique design solutions to ensure satisfactory operation over its design life. The development of the Aerospike is reviewed emphasizing the unique and interesting problems encountered and their solutions.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Johnson Space Center The 13th Aerospace Mech. Symp.; p 39-48
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  • 80
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    Gimbal bearing design considerations and friction control (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The design considerations of bearing selection, bearing fits, bearing installation, and thermal control are discussed for a gimbal with a high stiffness, low friction torque requirement. Tradeoffs between a quad set of small diameter spread apart or a large diameter bearing pair resulted in a cleaner, lighter, stiffer unit with the latter selection. Bearing fits were designed to eliminate clearances with tolerances of .00127 mm 00005 in) on the bearing shafts and housings. The problems in metrology are discussed and a perferred technique for measurement of small cross-section bearings described. A technique for installation to assure proper seating of the bearing is offered. Where transient thermal conditions are involved, a method of controlling bearing friction by active control of bearing temperature gradients including the use of bearing unload test curves is described.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Johnson Space Center The 13th Aerospace Mech. Symp.; p 71-81
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  • 81
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    The XFV-12A Thrust-Augmented Wing (TAW) prototype aircraft (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The XFV-12A, a unique V/STOL technology prototype aircraft being developed for the Navy, is described. The innovative design features a thrust augmented wing and a canard ejector. Structural, functional, and control test performances are discussed. Static tether test results are also discussed. Assessment of test results are given along with projections for future modification areas.
    Keywords: AERODYNAMICS
    Type: NASA. Ames Res. Center Workshop on Thrust Augmenting Ejectors; p 473-480
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  • 82
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    Reaction control system augmentation for V/STOL aircraft (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Advantages and problems associated with augmentation of reaction controls are discussed. The current status of compact ejector technology and the expected performance of known efficient designs for reaction control applications are presented.
    Keywords: AERODYNAMICS
    Type: NASA. Ames Res. Center Workshop on Thrust Augmenting Ejectors; p 417-436
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  • 83
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    On the rational design of compressible flow ejectors (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: A fluid mechanics review of chemical laser ejectors is presented. The characteristics of ejectors with single and multiple driver nozzles are discussed. Methods to compute an optimized performance map in which secondary Mach number and performance are computed versus mass ratio, to compute the flow distortion at each optimized condition, and to determine the thrust area for the design point to match diffuser impedence are examined.
    Keywords: AERODYNAMICS
    Type: NASA. Ames Res. Center. Workshop on Thrust Augmenting Ejectors; p 109-139
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  • 84
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    An overview of current Navy programs to develop thrust augmenting ejectors (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The primary objective of Navy sponsored research in thrust augmentation is the development of an improved augmenter for V/STOL application. In support of this goal, a data base is being established to provide an accurate prediction capability for use in ejector design. A general technology development of ejectors and associated effects presently is split into the more specific areas of lift and control, since thrust augmenting ejectors may be suitable for both. Research areas examined include advanced diffuser and end wall design; advanced primary nozzles; analytic studies; augmenting reaction controls; and nozzle design.
    Keywords: AERODYNAMICS
    Type: NASA. Ames Res. Center Workshop on Thrust Augmenting Ejectors; p 41-54
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  • 85
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    NASA overview (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The history of NASA efforts at Ames Research Center in researching the performance and application of thrusting augmentors is reviewed. Current objectives include: (1) parametric description of thrust augmentor application to STOL and V/STOL; (2) the use of theoretical and empirical data; (3) aircraft-augmentor integration; and (4) key design considerations for STOL transport and V/STOL fighter aircraft. Test facilities are described and ejector development and performance are assessed.
    Keywords: AERODYNAMICS
    Type: Workshop on Thrust Augmenting Ejectors; p 23-40
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  • 86
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    Design and test of a prototype scale ejector wing (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: A two dimensional momentum integral analysis was used to examine the effect of changing inlet area ratio, diffuser area ratio, and the ratio of ejector length to width. A relatively wide range of these parameters was considered. It was found that for constant inlet area ratio the augmentation increases with the ejector length, and for constant length: width ratio the augmentation increases with inlet area ratio. Scale model tests were used to verify these trends and to examine th effect of aspect ratio. On the basis of these results, an ejector configuration was selected for fabrication and testing at a scale representative of an ejector wing aircraft. The test ejector was powered by a Pratt-Whitney F401 engine developing approximately 12,000 pounds of thrust. The results of preliminary tests indicate that the ejector develops a thrust augmentation ratio better than 1.65.
    Keywords: AERODYNAMICS
    Type: NASA. Ames Res. Center Workshop on Thrust Augmenting Ejectors; p 437-448
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  • 87
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    Coannular supersonic ejector nozzles (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The nozzles described exhibit a flow field which is supersonic except for the initial flow region, and the secondary mass flow is typically about five percent of the primary core flow. The features to improve the accuracy of the performance calculations are discussed. A special calculation is made to get as realistic a sonic line as possible for this geometry, using an analysis developed by Brown. The mixing between the secondary and core flows is treated to account for entrainment of the secondary flow into core. Both of these phenomena directly affect the pressure distribution on the shroud and therefore, the thrust that the nozzle produces. The importance of using a realistic sonic line and a mixing analysis is stressed.
    Keywords: AERODYNAMICS
    Type: NASA. Ames Res. Center Workshop on Thrust Augmenting Ejectors; p 385-396
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  • 88
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    Integration of ejectors into high-speed aircraft (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The integration of ejectors into forebodies is considered for transonic and supersonic flight. Topics discussed include mixing flow in ducts, prediction of flow fields and external aerodynamics.
    Keywords: AERODYNAMICS
    Type: NASA. Ames Res. Center Workshop on Thrust Augmenting Ejectors; p 225-238
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  • 89
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    Augmenting ejector endwall effects (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Rectangular inlet ejectors which had multiple hypermixing nozzles for their primary jets were investigated for the effects of endwall blowing on thrust augmentation performance. The ejector configurations tested had both straight wall and active boundary layer control type diffusers. Endwall flows were energized and controlled by simple blowing jets suitably located in the ejector. Both the endwall and boundary layer control diffuser blowing rates were varied to determine optimum performance. High area ratio diffusers with insufficient endwall blowing showed endwall separation and rapid degradation of thrust performance. Optimized values of diffuser boundary layer control and endwall nozzle blowing rates in an ejector augmenter were shown to achieve high levels of augmentation performance for maximum compactness.
    Keywords: AERODYNAMICS
    Type: NASA. Ames Res. Center Workshop on Thrust Augmenting Ejectors; p 253-271
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  • 90
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    Internal-external flow integration for a thin ejector-flapped wing section (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Thin airfoil theories of an ejector flapped wing section are reviewed. The global matching of the external airfoil flow with the ejector internal flow and the overall ejector flapped wing section aerodynamic performance are examined. Mathematical models of the external and internal flows are presented. The delineation of the suction flow coefficient characteristics are discussed. The idealized lift performance of an ejector flapped wing relative to a jet augmented flapped wing are compared.
    Keywords: AERODYNAMICS
    Type: NASA. Ames Res. Center Workshop on Thrust Augmenting
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  • 91
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    Wind tunnel tests of four flexible wing ultralight gliders (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The aerodynamic lift, drag, and pitching moment characteristics of four full scale, flexible wing, ultralight gliders were measured in the settling chamber of a low speed wind tunnel. The gliders were tested over a wide range of angle of attack and at two different velocities. Particular attention was devoted to the lift and pitching moment behavior at low and negative angles of attack because of the potential loss of longitudinal stability of flexible wing gliders in this regime. The test results were used to estimate the performance and longitudinal control characteristics of the gliders.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Res. Center Sci. and Technol. of Low Speed and Motorless Flight; p 557-589
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  • 92
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    Development of a beam builder for automatic fabrication of large composite space structures (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The composite material beam builder which will produce triangular beams from pre-consolidated graphite/glass/thermoplastic composite material through automated mechanical processes is presented, side member storage, feed and positioning, ultrasonic welding, and beam cutoff are formed. Each process lends itself to modular subsystem development. Initial development is concentrated on the key processes for roll forming and ultrasonic welding composite thermoplastic materials. The construction and test of an experimental roll forming machine and ultrasonic welding process control techniques are described.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Johnson Space Center The 13th Aerospace Mech. Symp.; p 293-304
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  • 93
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    The impact of rare earth cobalt permanent magnets on electromechanical device design (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Specific motor designs which employ rare earth cobalt magnets are discussed with special emphasis on their unique properties and magnetic field geometry. In addition to performance improvements and power savings, high reliability devices are attainable. Both the mechanism and systems engineering should be aware of the new performance levels which are currently becoming available as a result of the rare earth cobalt magnets.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Johnson Space Center The 13th Aerospace Mech. Symp.; p 195-206
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  • 94
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    Development of drive mechanisms for communicaton satellites (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: A distinguished pedigree is an important asset in the development of Aerospace mechanisms. Four drives recently developed for communication satellites are outgrowths of a previously-proven drive configuration. Pedigree by itself, however is not enough to generate success. Inevitably, design changes which are thought to be minor, are generally introduced to fine tune the pedigreed hardware to meet particular requirements of a specific new application. Such design changes are often viewed too casually and are not thoroughly tested in the early development stages of the program. Two areas of design change are described on the solar array drive applied to the Japanese Broadcast Satellite which led to subsequent problems during the development phase of the program. The methods applied to establish the cause and the solution of these problems are described as well as the testing approach adapted to prevent similar occurrences on the current Communication Satellite Program, The Defense System Communications Satellite III.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Johnson Space Center The 13th Aerospace Mech. Symp.; p 151-166
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  • 95
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    Design of a piezoelectric shaker for centrifuge testing (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The design of a prototype piezoelectric shaker and its development to date is described. Although certain design problems remain to be solved, the piezoelectric system shows promise for adaptation to a larger payload system, such as the proposed geotechnical centrifuge at the Ames Research Center.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Johnson Space Center The 13th Aerospace Mech. Symp.; p 59-70
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  • 96
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    Design and development of a motion compensator for the RSRA main rotor control (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The RSRA, an experimental helicopter, is equipped with an active isolation system that allows the transmission to move relative to the fuselage. The purpose of the motion compensator is to prevent these motions from introducing unwanted signals to the main rotor control. A motion compensator concept was developed that has six-degree-of-freedom capability. The mechanism was implemented on RSRA and its performance verified by ground and flight tests.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Johnson Space Center The 13th Aerospace Mech. Symp.; p 15-25
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  • 97
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    Some new airfoils (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: A computer approach to the design and analysis of airfoils and some common problems concerning laminar separation bubbles at different lift coefficients are briefly discussed. Examples of application to ultralight airplanes, canards, and sailplanes with flaps are given.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Res. Center The Sci. and Technol. of Low Speed and Motorless Flight, Pt. 1; p 131-154
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  • 98
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    Generation and breakdown of aerodynamic lift: Physical mechanism (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: A contribution is given to an old problem: the explanation of the generation of aerodynamic lift. Physical models are described which provide a better understanding of the phenomena involved.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Res. Center The Sci. and Technol. of Low Speed and Motorless Flight, Pt. 1; p 93-102
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  • 99
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    Length and bursting of separation bubbles: A physical interpretation (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: A physical interpretation of the observed form of the pressure distribution beneath a two-dimensional separation bubble which modified the external inviscid pressure distribution only locally is given in terms of boundary layer concepts. A simple method for estimating along a mean streamline entrained into the underside of a growing shear layer through the transition region is discussed, and predictions of bubble bursting conditions and a lower bound on the bubble length are compared with experiment.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Res. Center The Sci. and Technol. of Low Speed and Motorless Flight, Pt. 1; p 177-202
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  • 100
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    The effect of disturbance on a wing (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Disturbances such as flap and aileron hinges and poorly faired spoilers were simulated in a computer wind tunnel. The total drag of a single roughness element does not depend only on the size of that element. Its position on the wing has a surprisingly strong effect. In particular, a roughness element on the convex side of a deflected flap or aileron causes a very substantial increase in drag. Very few experimental data are available for comparison. Good agreement with experiment can be achieved, however, by adapting a fictive step size. The correlation between the real roughness-element size and the drag increase remains to be determined. Simple, fundamental experiments are suggested which will allow a theoretical estimation of the drag increase due to roughness elements.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Res. Center The Sci. and Technol. of Low Speed and Motorless Flight, Pt. 1; p 81-92
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