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Showing papers by "Langley Research Center published in 1968"


01 Aug 1968
TL;DR: In this article, the buckling of cylindrical shells under various types of static and dynamic loadings is discussed, and the procedures that yield estimates of static buckling loads considered to be conservative.
Abstract: This monograph indicates current practices for predicting buckling of uniform stiffened and unstiffened circular cylindrical shells under various types of static loading, and suggests the procedures that yield estimates of static buckling loads considered to be conservative. The buckling of truncated conical shells and shells of double curvature will be treated in separate monographs.

271 citations


Journal ArticleDOI
TL;DR: Amplitude frequency relations of nonlinear vibrations in uniform beams with various boundary conditions using perturbation method was studied in this paper, where the amplitude frequency relations were obtained for uniform beams.
Abstract: Amplitude frequency relations of nonlinear vibrations in uniform beams with various boundary conditions using perturbation method

146 citations




Journal ArticleDOI
TL;DR: Free vibration analysis for ring and stringer stiffened cylindrical shell, using Rayleigh-Ritz technique, was performed in this paper, where the authors used the Rayleigh Ritz technique.
Abstract: Free vibration analysis for ring and stringer stiffened cylindrical shell, using Rayleigh-Ritz technique

80 citations


01 Oct 1968
TL;DR: Empirical stagnation point-heat transfer relation in gas mixtures at high enthalpy potentials was studied in this article, where the point heat transfer relation was shown to be stable.
Abstract: Empirical stagnation point-heat transfer relation in gas mixtures at high enthalpy potentials

75 citations


01 Sep 1968
TL;DR: Vibration tests and analysis of thin cylindrical shells with and without longitudinal stiffeners were performed in this article, showing that they can be classified into three classes: cylindric shells with, without, and with longitudinal stiffener.
Abstract: Vibration tests and analysis of thin cylindrical shells with and without longitudinal stiffeners

71 citations


01 Aug 1968
TL;DR: In this paper, the leading edge suction analogy of vortex lift was used to predict delta wing drag by applying of leading edge SUction analogy to vortex lift, and the results showed that the resulting prediction was correct.
Abstract: Sharp edge delta wing drag prediction by application of leading edge suction analogy of vortex lift

67 citations


Journal ArticleDOI
TL;DR: In this article, the authors derived the input admittance of a circular waveguide opening onto an infinite flange with a homogeneous lossy dielectric coating using integral transforms and assuming the dominant TE 11 mode as the trial field at the aperture.
Abstract: The input admittance of a circular waveguide opening onto an infinite flange with a homogeneous lossy dielectric coating is derived using integral transforms and assuming the dominant TE 11 mode as the trial field at the aperture. Admittance calculations for low-loss dielectric sheets of various thicknesses are given and compared with measurements obtained using ground planes of varying sizes. Excellent agreement with theory is obtained for the circular waveguide terminated into a square ground plane only 1\lambda to 2\lambda . on a side. A quantitative comparison of the surface wave contribution to the total admittance is also given.

48 citations


01 Jul 1968
TL;DR: In this article, a computer program predicting lifting pressure and camber shape of composite planform in subsonic flow is proposed to predict the camber and lifting pressure of a planform.
Abstract: Supplementary information for computer program predicting lifting pressure and camber shape of composite planform in subsonic flow

47 citations


Journal ArticleDOI
TL;DR: Peak heating correlated with reattachment of both laminar and turbulent separated flows on flaps was found to be correlated with the performance of flow separation on the flaps.
Abstract: Peak heating correlated with reattachment of both laminar and turbulent separated flows on flaps

Journal ArticleDOI
TL;DR: In this article, the admittance of a waveguide-fed rectangular aperture under an inhomogeneous plasma is derived and experimentally verified, for both flowing and stationary inhomogeneoas plasmas, the agreement is at least as accurate as presently available plasma diagnostic techniques will allow.
Abstract: The admittance of a waveguide-fed rectangular aperture under an inhomogeneous plasma is derived and experimentally verified. For both flowing and stationary inhomogeneoas plasmas, the agreement is at least as accurate as presently available plasma diagnostic techniques will allow. It is shown that there is a clear separation of the dependence of aperture-admittance properties upon plasma properties, such as electron density, profile shape and collision frequency, over two to three decades of peak electron density, change. The collision frequency primarily affects the aperture conductance, particularly for critical and overdense plasmas. The profile shape, i.e., a boundary layer, primarily affects the aperture susceptance.

01 May 1968
TL;DR: The FORTRAN program for approximate calculation of supersonic ideal gas flow past blunt bodies with sonic corners shows good agreement with prior work on this topic.
Abstract: FORTRAN program for approximate calculation of supersonic ideal gas flow past blunt bodies with sonic corners

Journal ArticleDOI
TL;DR: Hypersonic flow distribution and separation types over highly swept delta wings with trailing edge flaps at Mach 6 were presented in this article, showing that the delta wing is capable of flying at a speed of Mach 6.
Abstract: Hypersonic flow distribution and separation types over highly swept delta wings with trailing edge flaps at Mach 6


Journal ArticleDOI
TL;DR: In this paper, the authors extended the Dugdale model to include the influence of the stress-strain curve on the plastic-zone size and subsequently on the fracture strength of the plate.

01 Nov 1968
TL;DR: A 40-foot-nominal-diameter (12.2 meter) disk-gap-band parachute was flight tested as part of the NASA Supersonic Planetary Entry Decelerator (SPED-I) Program as discussed by the authors.
Abstract: A 40-foot-nominal-diameter (12.2 meter) disk-gap-band parachute was flight tested as part of the NASA Supersonic Planetary Entry Decelerator (SPED-I) Program. The test parachute was deployed from an instrumented payload by means of a deployment mortar when the payload was at an altitude of 158,500 feet (48.2 kilometers), a Mach number of 2.72, and a free-stream dynamic pressure of 9.7 pounds per foot(exp 2) (465 newtons per meter(exp 2)). Suspension line stretch occurred 0.46 second after mortar firing and the resulting snatch force loading was -8.lg. The maximum acceleration experienced by the payload due to parachute opening was -27.2g at 0.50 second after the snatch force peak for a total elapsed time from mortar firing of 0.96 second. Canopy-shape variations occurred during the higher Mach number portion of the flight test (M greater than 1.4) and the payload was subjected to large amplitude oscillatory loads. A calculated average nominal axial-force coefficient ranged from about 0.25 immediately after the first canopy opening to about 0.50 as the canopy attained a steady inflated shape. One gore of the test parachute was damaged when the deployment bag with mortar lid passed through it from behind approximately 2 seconds after deployment was initiated. Although the canopy damage caused by the deployment bag penetration had no apparent effect on the functional capability of the test parachute, it may have affected parachute performance since the average effective drag coefficient of 0.48 was 9 percent less than that of a previously tested parachute of the same configuration.

01 Apr 1968
TL;DR: In this paper, the effects of dynamic hydroplaning, viscous and tire tread rubber reversion effects on tire traction on wet runways were investigated. And the results showed that the effect of these effects varied with the type of terrain.
Abstract: Dynamic hydroplaning, viscous hydroplaning, and tire tread rubber reversion effects on tire traction on wet runways

01 Oct 1968
TL;DR: Static and dynamic characteristics of wind tunnel model of parallel staged reusable launch vehicle during stage separation were analyzed in this article, showing that the model can be used to simulate the performance of a stage separation.
Abstract: Static and dynamic characteristics of wind tunnel model of parallel staged reusable launch vehicle during stage separation

Journal ArticleDOI
TL;DR: Mie total and differential backscattering cross sections at laser wavelengths for Junge size distribution aerosol models show good agreement between the sizes of the particles and the spacing between them.
Abstract: Mie total and differential backscattering cross sections at laser wavelengths for Junge size distribution aerosol models

01 May 1968
TL;DR: In this paper, a wind tunnel study of unsteady lift forces generated by vortex shedding about large, stationary, and oscillating cylinder at high Reynolds numbers is presented, showing that the lift forces are generated by a large and stationary, stationary and oscillated cylinder.
Abstract: Wind tunnel study of unsteady lift forces generated by vortex shedding about large, stationary, and oscillating cylinder at high Reynolds numbers


Dissertation
01 Jan 1968
TL;DR: Prebuckling deformations and ring stiffener effects on buckling load of eccentrically stiffened orthotropic cylinders were studied in this paper, showing that ring stiffeners have a strong effect on the buckling of orthogonal cylinders.
Abstract: Prebuckling deformations, and ring stiffener effects on buckling load of eccentrically stiffened orthotropic cylinders


Journal ArticleDOI
TL;DR: In this paper, an experimental investigation to locate the beginning of transition from laminar to turbulent boundary-layer flow has been conducted at zero angle of attack on sharp, smooth cones having semiapex angles of 2.87°, 5°, and 10° in the contoured nozzle of the Langley 22-in. helium tunnel at a freestream Mach number of about 20.8.
Abstract: An experimental investigation to locate the beginning of transition from laminar to turbulent boundary-layer flow has been conducted at zero angle of attack on sharp, smooth cones having semiapex angles of 2.87°, 5°, and 10° in the contoured nozzle of the Langley 22-in. helium tunnel at a freestream Mach number of about 20. Local Mach number at the boundarylayer edge was thus varied from 7.4 to 16.6. The data indicate that local transition Reynolds number increases rapidly with local Mach number. Techniques used to detect onset of transition included surface pilot tube, drag force, boundary-layer pitot-pressure surveys, schlieren photographs, and hot-film anemometer measurements. Skin-friction coefficient, displacement thickness, momentum thickness, and velocity ratio profiles were determined for laminar, transitional, and turbulent hypersonic boundary layers. A hot-film anemometer survey of the model boundary layers showed disturbances originating within the boundary layer at much lower Reynolds numbers than the Reynolds number for which transition is felt at the model surface. The maximum disturbance level occurred at a location corresponding to about 0.845 (boundary-layer thickness) with the disturbance speed being subsonic relative to the local edge velocity. In addition, source flow effects on transition Reynolds number were examined at a local Mach number of 15.8.

Journal ArticleDOI
TL;DR: Ballistic propellant combustion alteration and thermal effects due to dynamic spinning observed on solid propellant sounding rockets were studied in this article, showing that the effects of dynamic spinning on sounding rockets can be significant.
Abstract: Ballistic propellant combustion alteration and thermal effects due to dynamic spinning observed on solid propellant sounding rockets

Journal ArticleDOI
TL;DR: In this paper, the degradation of polyimidazopyrrolone /pyrrone/ films in air and vacuum using thermogravimetric analysis has been studied.
Abstract: Thermal degradation of polyimidazopyrrolone /pyrrone/ films in air and vacuum, using thermogravimetric analysis


01 Aug 1968
TL;DR: In this paper, the infrared horizon radiance profiles obtained during summer conditions with Project Scanner probe were used to study the effect of weather conditions on the visible light spectrum of the horizon.
Abstract: Infrared horizon radiance profiles obtained during summer conditions with Project Scanner probe

Journal ArticleDOI
TL;DR: In this paper, a double-ellipso idalmirror reflectometer that utilizes a carbon arc to heat and to irradiate the materials was used to measure the visible and near-infrared spectral reflectance and emittance of ablation chars, carbon, and graphite at temperatures ranging from 2200° to 3500° K.
Abstract: Initial results of an experimental study of the visible and near-infrared spectral reflectance and emittance of ablation chars, carbon, and graphite at temperatures ranging from 2200° to 3500° K are presented Reflectance measurements were made with a double-ellipso idalmirror reflectometer that utilizes a carbon arc to heat and to irradiate the materials The ablation materials, from which the chars were formed by thermal degradation in atmosphericentry-simulation facilities, included high-density and low-density phenolic-nylon, carbonfiber-reinforced phenolic, and honeycomb-reinforced, low-density filled epoxy Measurements were made on a dense high-purity and a porous grade of carbon and on high-purity, structural, and pyrolytic grades of graphite A photomultiplier and a lead sulfide cell were used as detectors for the visible and infrared measurements, respectively The results indicate that emittance for all the materials is maximum in the visible spectrum and decreases with wavelength in the near-infrared spectrum The angular distributions of radiation fluxes incident on, reflected from, and radiated from, each material, were measured with an array of solar cells The distribution measurements showed that the materials whose surfaces are porous or have been roughened by oxidation obey Lambert's cosine law approximately in the emission of radiation, and also in reflecting the arc incident radiation, although the incident radiation is nonuniform in distribution