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Shell analysis manual provides methods for determining static deflections and internal load and stress distributions in shells under various loading conditions, and methods of analyzing static instability of shell structures. Also included are methods for determining the lightest shell wall for various constructions.
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The effect of shuttle configuration geometry, angle of attack, and free stream flow conditions on the heat-transfer distribution as influenced by three-dimensional effects, the wing-fuselage shock-interaction, and resultant wing-impingement phenomena are examined. In addition, the data provided information regarding the flow field in the vicinity of the nose and boundary layer transition in the plane of symmetry of the fuselage. The data included measurements of the surface pressure, the heat transfer rate distributions, (using models instrumented with thermocouples and models painted with thermographic phosphor) and schlieren and shadowgraph photographs. Posttest photographs of the painted models supplemented the heat transfer data.
Comparison of airborne optical measurements during December 1969 with satellite particle measurements made earlier in 1969. The latitudinal distributions of H beta, 4278-A and 6300-A emissions during quiet periods are observed to agree with what would be expected from the latitudinal distribution of particle precipitation during similar conditions. In particular, there is a belt 200 to 500 km wide (at ionospheric heights) in which the magnetosheath plasma penetrates down to low altitudes through the cusps in the dayside magnetosphere and in which both H beta and 6300-A emissions are observed. There are brighter red arcs with green lower borders within this belt. It is suggested that these are produced by narrow regions of precipitation of slightly more energetic electrons embedded in the cusp fluxes. Poleward of this belt the flux of particles is low, and the atmospheric emissions are very weak, except for occasional narrow regions of electron precipitation (without measurable protons) and the corresponding polar-cap aurora (without the H beta emission).
The evolution of a disturbance in the presence of a uniform mean velocity gradient is calculated by a power-series solution of the incompressible Navier-Stokes equations. Terms through those in time cubed are retained in the solution. For the initial condition a three-dimensional cosine distribution with two harmonic terms is assumed. The nonlinear interaction of these harmonic terms produces new harmonics which in turn interact. For large velocity gradients the energy of the disturbance can grow with time. The results shed some light on the maintenance or growth of turbulence in a shear flow.
The contamination controls used in the Lunar Receiving Laboratory during the processing of lunar samples are described. Initially, the lunar sample containers were opened and the material was examined in a vacuum complex with approximated lunar surface conditions. The process of examining and distributing the samples from this vacuum complex was time consuming. During both Apollo 11 and 12 missions portions of the lunar samples were processed for allocation in a small sterile glove box in a dry nitrogena atmosphere. After Apollo 12 a new system was installed based upon the experience gained from the small glove box. The system uses dry nitrogen as an environmental blanket and has the capability of being sterilized and of maintaining this sterility.
Objectives of the test were to obtain static pressure distributions for the ET at reentry conditions. Basic configuration of the model was the MCR 0200 ET modified to include a rectangular crossbar at the aft ET/orbiter attach point. Mach numbers were 1.96, 3.48, and 4.96. Reynolds number per foot at these Mach numbers were 6.95 million, 6.42 million, and 4.95 million, respectively. Angle of attack range was -8 to 100 degrees and roll angle was 0 to 315 degrees. Occupancy hours were 104.
OSO 7 observations of a hard X-ray event of coronal origin are described. This event had a duration of more than 42 min as well as an abnormally large hard/soft ratio and apparently occurred after the disappearance of a bright coronal streamer. This gradual hard X-ray event is tentatively associated with open field lines extending well above the closed loop structures that participated in the originating flare. It is noted that a gradual hardening of the hard X-ray spectral distribution occurred during the event. Physical conditions in the source are considered, and the results are compared with observations of other hard X-ray events associated with flares.
The development of aircraft gust design techniques is reviewed with emphasis on those techniques applicable to large scale multidisciplinary closed-loop optimization methods. An overall view is presented of the optimization methodology utilized. An analysis is presented wherein the bivariate normal distribution function for a particular loading condition is considered. By use of maximization techniques, functions are derived for stress components along equal probability contours which allow for directionality and auto-correlation effects to be considered. These functions are then applied to the problem being considered and the effects on the structural sizing and weight penalties evaluated against more conventional methods.
Charged and neutral particle transport from an 8 cm mercury ion thruster to the surfaces of the P 80-1 spacecraft and to the Teal Ruby sensor and the ECOM-501 sensor of that spacecraft were investigated. Laboratory measurements and analyses were used to examine line-of-sight and nonline-of sight particle transport modes. The recirculation of Hg(+) ions in the magnetic field of the earth was analyzed for spacecraft velocity and Earth magnetic field vector configurations which are expected to occur in near Earth, circular, high inclination orbits. For these magnetic field and orbit conditions and for expected ion release distribution functions, in both angles and energies, the recirculation/re-interception of ions on spacecraft surfaces was evaluated. The refraction of weakly energetic ions in the electric fields of the thruster plasma plume and in the electric fields between this plasma plume and the material boundaries of the thruster, the thruster sputter shield, and the various spacecraft surfaces were examined. The neutral particle transport modes of interest were identified as sputtered metal atoms from the thruster beam shield. Results, conclusions, and future considerations are presented.
The GLAS General Circulation Model (GCM) was applied to the four-month simulation of the thermodynamic part of the Parkinson-Washington sea ice model using atmospheric boundary conditions. The sea ice thickness and distribution were predicted for the Jan. 1-Apr. 30 period using the GCM-fields of solar and infrared radiation, specific humidity and air temperature at the surface, and snow accumulation; the sensible heat and evaporative surface fluxes were consistent with the ground temperatures produced by the ice model and the air temperatures determined by the atmospheric concept. It was concluded that the Parkinson-Washington sea ice model results in acceptable ice concentrations and thicknesses when used with GLAS GCM for the Jan.-Apr. period suggesting the feasibility of fully coupled ice-atmosphere simulations with these two approaches.
Image simulation techniques were employed to establish the relationship between spatial resolution and the accuracy of soil moisture estimated by an imaging radar. A spaceborne synthetic aperture radar at an orbital altitude of 600 km, operating at 4.5 GHz with HH polarization configuration and covering a ground swath width of 143 km corresponding to an angle of incidence range extending between 7-22 degrees relative to the vertical, provided the images simulated by a 17.7 km x 19.3 km test site. The role of resolution was evaluated by simulating various sets of images with resolutions ranging from 20 m x 20 m to 1 km x 1 km. Each simulated image was subjected to a soil moisture prediction algorithm whose input is limited to the image intensity level. Results show that the 1 km x 1 km resolution provides the best prediction accuracy for most soil moisture distributions except for drought-like conditions for which the 100 m x 100 m resolution is found to be preferred. In general it was found that the soil moisture of about 90% of the pixels is predicted with an error of + or - 20% of field capacity or less.
The objectives are to use model transparent monotectics to obtain fundamental information applicable to two-phase systems in general, to apply this understanding to materials of interest in the Microgravity Science and Applications program, and to interpret results of flight experimental involving monotectic alloys. A number of model immiscible systems are in use to study various aspects of two-phase behavior within the miscibility gap and during solidification. Particle growth, coalescence and particle motions are under investigation using a holographic microscopy system. The system is capable of working with particle densities up to 10 to the 7th power particles/cubic centimeters through a 100 micron depth and can resolve particles of the order of 2 to 3 micron in diameter throughout the entire cell volume. Particle size, distribution changes with respect to time and temperature are observable from sequential holograms. Initial experiments using diethylene glycol/ethyl salicylate (DEG/ES) have demonstrated the usefulness of the technique. The thermal system controls temperature to at least plus or minus 0.001 K over the course of an experiment. A time-lapse film, made from holograms, of a succinonitrile/water solution shows particle size and number distribution changes with time under isothermal conditions. The observations are consistent with Ostwald ripening theory.
A flexible supercritical research wing, designated as ARW-1, was flight-tested as part of the NASA Drones for Aerodynamic and Structural Testing Program. Aerodynamic loads, in the form of wing surface pressure measurements, were obtained during flights at altitudes of 15,000, 20,000, and 25,000 feet at Mach numbers from 0.70 to 0.91. Surface pressure coefficients determined from pressure measurements at 80 orifice locations are presented individually as nearly continuous functions of angle of attack for constant values of Mach number. The surface pressure coefficients are also presented individually as a function of Mach number for an angle of attack of 2.0 deg. The nearly continuous values of the pressure coefficient clearly show details of the pressure gradient, which occurred in a rather narrow Mach number range. The effects of changes in angle of attack, Mach number, and dynamic pressure are also shown by chordwise pressure distributions for the range of test conditions experienced. Reynolds numbers for the tests ranged from 5.7 to 8.4 x 1,000,000.
The excitation mechanism for broadband electrostatic noise (BEN) and the effects of BEN particles in the geomagnetic tail are examined using the linear analysis theory and particle simulations. The linear theory for electrostatic instabilities is discussed. The plasma sheet particle population is simulated using counter-streaming cold ion beams, and warm ions and electrons. The ion-ion instability, ion-acoustic mode, and the electrostatic ion cyclotron harmonic waves are studied. The velocity distributions, electric field intensity, and electron plasma waves for the plasma sheet boundary layer are evaluated. The frequency wave spectrum and particle distributions are computed and analyzed. The conditions for the two simulations, which differ only in beam ion drift speed, are described; it is observed that in the first simulation the dominate modes propagate parallel to the magnetic field and in the second simulation the propagation modes are oblique. The simulation data reveal that when beam temperature is smaller than plasma sheet temperature ion-acoustic and ion-ion instabilities grow to large amplitudes heating both electrons and ions. The data are compared to ISEE-1 observations and good correlation is obtained.
Cometary plasma tail formation by the interaction between the solar wind plasma flow and the plasma at the head of the coma is discussed using the unipolar electric generation theory. The plasma in the 'plasma tail' is almost directly accelerated from the cometary ionopause along the sun-nucleus line where the tail current flows. For steady state solar wind conditions, the cometary 'plasma tail' velocity distribution is obtained self-consistently. The solution of a kinetic equation gives the velocity of the cometary plasma as a function of the cometary tail position. The characteristic length is 3 x 10 to the 6th km when the plasma density near the nucleus of the comet is 10 to the 6th/cu cm and the component of the interplanetary magnetic field perpendicular to the solar wind flow is 3 nT. The tailward cometary plasma is finally accelerated to the speed of the solar wind. The theory is compared with the observational plasma velocities in the tails of comet Bennett (1970II) and Comet Halley (1985).
A Probabilistic Hu-Washizu Variational Principle (PHWVP) for the Probabilistic Finite Element Method (PFEM) is presented. This formulation is developed for both linear and nonlinear elasticity. The PHWVP allows incorporation of the probabilistic distributions for the constitutive law, compatibility condition, equilibrium, domain and boundary conditions into the PFEM. Thus, a complete probabilistic analysis can be performed where all aspects of the problem are treated as random variables and/or fields. The Hu-Washizu variational formulation is available in many conventional finite element codes thereby enabling the straightforward inclusion of the probabilistic features into present codes.
The Technical Facilities Controller is a microprocessor-based energy management system that is to be implemented in the Deep Space Network facilities. This system is used in conjunction with facilities equipment at each of the complexes in the operation and maintenance of air-conditioning equipment, power generation equipment, power distribution equipment, and other primary facilities equipment. The implementation of the Technical Facilities Controller was completed at the Goldstone Deep Space Communications Complex and is now operational. The installation completed at the Goldstone Complex is described and the utilization of the Technical Facilities Controller is evaluated. The findings will be used in the decision to implement a similar system at the overseas complexes at Canberra, Australia, and Madrid, Spain.