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Single integral unit includes motor, gearbox, and clutch. Device has two-speed capability, fits within aerodynamic contours of aircraft, operates with onboard power source, does not interfere with normal landing gear functions, reduces use of regular brakes in congested areas, and provides locomotion and supplementary braking capability.
Numerical solutions of the laminar, incompressible boundary layer equations are presented for flows involving separation and reattachment. Regular solutions are obtained with an inverse approach in which either the displacement thickness or the skin friction is specified; the pressure is deduced from the solution. A vorticity-stream-function formulation of the boundary layer equations is used to eliminate the unknown pressure. Solutions of the resulting finite difference equations, in which the flow direction is taken into account, are obtained by several global iteration schemes which are stable and have unconditional diagonal dominance. Results are compared with Klineberg and Steger's separated boundary layer calculations, and with Briley's solution of Navier-Stokes equations for a separated region. In addition, an approximate technique is presented in which the streamwise convection of vorticity is set equal to zero in the reversed flow region; such a technique results in a quick forward marching procedure for separated flows.
The author has identified the following significant results. The program has demonstrated that Skylab imagery can be utilized to regularly monitor eutrophication indices of lakes, such as chlorophyll concentration and photic zone depth. The relationship between the blue to green reflectance ratio and chlorophyll concentration was shown, along with changes in lake properties caused by chlorophyll, lignin, and humic acid using reflectance ratios and changes. A data processing technique was developed for detecting atmospheric fluctuations occurring over a large lake.
Streptomyces levoris was used as an experimental microorganism during the Apollo Soyuz Test Project to study specific biological considerations that may be influenced by space flight factors. Preflight, inflight, and postflight growth rates of the cultures were compared by photographing the specimens at regular intervals. Preliminary results based on visual comparison of the photographic data indicate that an increased growth rate occurred during space flight in two of eight flight specimens. The increased growth rate continued in the two specimens during the postflight period until termination of the experiment. Radiation effects may be responsible for the absence of spores in two areas of the last spore ring that was formed during the inflight period in one of the flight cultures; however, the radiation studies related to this experiment have not been completed. Distinct morphological differences in spore rings were observed when postflight spore rings were compared with inflight spore rings. Factors that are related to space flight recovery and reentry into earth gravity may have effected these alterations.
The author has identified the following significant results. Studies in the Ice-Free Valleys are resulted in the compilation of a sizeable library of maps and publications. Rock reflectance measurements were taken during the Antarctic summer of 1973. Spectral reflectance of rocks (mostly mafic lava flows) in the McMurdo and Ice-Free Valleys areas were measured using a filter wheel photometer equipped to measure reflectances in the four Landsat bands. A series of samples were collected at regular intervals across a large differentiated, mafic sill near Lake Vida. Chemical analyses of the sample suggest that the tonal variations in this sill are controlled by changes in the iron content of the rock. False color images were prepared for a number of areas by the diazo method and with an optical multispectral biviewer. These images were useful in defining boundaries of sea ice, snow cover, and in the study of ablating glaciers, but were not very useful for rock discrimination.
The managers of the NASA Scientific and Technical Information System consistently maintain that whatever scientific and technical information services and products are provided must be geared primarily to user needs and not simply system compatibility and convenience. A system evaluation study begun in 1973 and continued to the present is described. The thrust of this on-going examination is to regularly evaluate the usefulness of the present information system to those it is intended to serve, engineers and scientists working in their professional roles, and to identify areas and ways in which the system can be made more responsive to user needs. Techniques used have covered the range from personal, in-depth interviews to widely distributed questionnaires. The findings have been positive. Many refinements made to on-going programs and projects and new endeavors begun in direct response to stated user needs are discussed. In the main these needs are not unreasonable and thus can be responded to with cost effective system modifications.
An experiment was designed to test the ability of the Classification and Mensuration Subsystem rework operations to improve wheat proportion estimates for segments that had been processed previously. Sites selected for the experiment included three in Kansas and three in Texas, with the remaining five distributed in Montana and North and South Dakota. The acquisition dates were selected to be representative of imagery available in actual operations. No more than one acquisition per biophase were used, and biophases were determined by actual crop calendars. All sites were worked by each of four Analyst-Interpreter/Data Processing Analyst Teams who reviewed the initial processing of each segment and accepted or reworked it for an estimate of the proportion of small grains in the segment. Classification results, acquisitions and classification errors and performance results between CAMS regular and ITS rework are tabulated.
The advantages of a regular program of daily observations of the magnetosphere, ionosphere and atmosphere are described. Such synoptic observations may be one of the best routes to understanding the physical mechanisms involved in sun-weather influences. Some specific examples of such observations are given.
The HP-9810A calculator programs described provide the capability to generate HP-9862A plotter displays which depict the apparent motion of a free-flying cyclindrical payload relative to the shuttle orbiter body axes by projecting the payload geometry into the orbiter plane of symmetry at regular time intervals.
Growth of organic compounds from solution, in particular Rochelle salt and triglycine sulphate, was investigated. Ground-based experiments showed that gravity-driven convection currents in the growth solution influenced defect production in crystals, degraded ferroelectric quality, and indicated that an experiment done in a zero-gravity environment would be beneficial. A crystal of Rochelle salt was grown on board Skylab-4. The quality of this crystal was compared to earth-grown crystals and its unusual features were studied. A typical defect produced in this convection-free environment was a long straight tube extending in the direction of the c crystal axis. These tubes were much longer and more regularly arranged than in similar earth-grown crystals. The crystal was actually several crystals with corresponding axes parallel to each other. Ferroelectric hysteresis experiments showed that some parts of the crystal had many defects, while other parts were of extremely good quality.
A grid of flux-constant model atmospheres for stars with effective temperatures between 3750 and 6000 K, log g between 0.75 and 3.0, and (A/H) between -3.0 and 0.0 has been constructed. The line absorption is approximated by opacity distribution functions. Metal lines and molecular lines, including those from the infrared bands of CO and CN, are taken into account. The variation of the structure of the models with metal abundance and microturbulence parameter is found to be quite regular and not very drastic. The surface cooling produced by CO is important for all the models with a maximum temperature of 5000 K, while CN mainly causes a backwarming effect but is not very important for solar CNO abundances. The effects of convection, estimated by using the mixing-length approximation, are important only for the coldest models. The models compare very well with models from overlapping regions of other grids. A solar model consistent with the grid models is found to agree satisfactorily with empirical solar model atmospheres. The careful use of scaled solar models for stars with (A/H) approximately equal to zero is justified.
Using the slender inclusion model developed earlier the elastostatic interaction problem between a penny-shaped crack and elastic fibers in an elastic matrix is formulated. For a single set and for multiple sets of fibers oriented perpendicularly to the plane of the crack and distributed symmetrically on concentric circles the problem is reduced to a system of singular integral equations. Techniques for the regularization and for the numerical solution of the system are outlined. For various fiber geometries numerical examples are given and distribution of the stress intensity factor along the crack border is obtained. Sample results showing the distribution of the fiber stress and a measure of the fiber-matrix interface shear are also included.
The suprathermal ion detector experiment regularly observes ion events normally ranging from 250 eV/q to 1000 eV/q all through the lunar night. These ion events occur most often 2 to 3 days prior to the sunrise terminator. There is also a secondary activity peak 3 to 4 days after local sunset on the moon. The events are normally of 4 hr or less in duration, and the integral flux is 1 million ions per sq cm/sec/sr. This article discussed the character of these events and presents preliminary findings of a detailed study on this subject.
Preliminary results of the Applications Technology Satellite-6 (ATS-6) solar cell flight experiment to isolate and identify solar cell degradation mechanisms resulting from particulate radiation and to obtain specific design data applicable to extended synchronous spacecraft missions are presented. The experiment includes 80 individual cells representing 16 different solar cell/cover glass configurations. Most of the cells are 0.030 cm thick boron doped n/p cells with 10 ohm cm resistivity and solder-coated AgTi contacts. The voltage-current characteristics were measured regularly. The data for the first 325 days of flight show short circuit currents 1-8% higher than measurements made with solar simulations. Maximum power varied between -1 and +6%. After 50 days in orbit the degradation of short circuit current due to ultraviolet effects was determined to be about 2%. All cells except those with fluorinated ethylene propylene covers performed well after 325 days.
An upper tropospheric and hemispheric scale data set, resulting from the EOLE constant density balloon experiment (conducted between August 1971 and July 1972) is used to study the spatial variation of various measured and derived fields. The quality and density of the data set is shown to be sufficient for such a study during the Southern Hemisphere spring, summer and autumn of the data period but inadequate during winter. The stationary modes of the Southern Hemisphere are shown to be relatively weak compared to their Northern Hemisphere counterparts and possess distinct seasonal phase shifts. The transient fields, on the other hand, show definite longitudinal anomalies in their seasonal mean properties with magnitudes up to thrice the zonal average. The transient fields show little seasonal variability in position. Furthermore, it appears that most of their magnitude results from the contribution of a relatively few but extremely intense disturbances which appear to possess a fairly regular variability in the 18-23 day range.
Previous experience during Apollo postflight exercise testing indicated no major changes in pulmonary function. Pulmonary function has been studied in detail following exposure to hypoxic and hyperoxic normal gravity environments, but no previous study has reported on men exposed to an environment that was both normoxic at 258 torr total pressure and at null gravity as encountered in Skylab. Forced vital capacity (FVC) was measured during the preflight and postflight periods of the Skylab 2 mission. Inflight measurements of vital capacity (VC) were obtained during the last 2 weeks of the second manned mission (Skylab 3). More detailed pulmonary function screening was accomplished during the Skylab 4 mission. The primary measurements made during Skylab 4 testing included residual volume determination (RV), closing volume (CV), VC, FVC and its derivatives. In addition, VC was measured in flight at regular intervals during the Skylab 4 mission. Vital capacity was decreased slightly (-10%) in flight in all Skylab 4 crewmen. No major preflight-to-postflight changes were observed. The Apollo-Soyuz Test Project (ASTP) crewmen were studied using equipment and procedures similar to those employed during Skylab 4. Postflight evaluation of the ASTP crewmen was complicated by their inadvertent exposure to nitrogen tetroxide gas fumes upon reentry.
Data from X-ray diffraction studies of the poly(carbon monofluoride) with empirical formula CF(1.09-1.15) are reported, and possible intercalation arrangements for the substance are discussed. The data do not conform to true hexagonal symmetry, indicating that the carbon atoms are not coplanar. Each bond angle of carbon is 118.8 deg, and the carbon-carbon distance is 1.47 A. The interlayer distance is 5.76 A. A total absence of (hkl) reflections in the X-ray pattern shows that the separate CF layers are not regularly arranged with respect to one another.
Subcritical crack growth in a linear viscoelastic material subjected to cyclic loading is investigated starting with the thermodynamic power balance. Physically, it is supposed that the subcritical slow crack growth is due to local weakening of the material in the neighborhood of the crack tip. Under fatigue loading it is assumed that all energy dissipation goes into heat and that this heat build-up is the dominant irreversible process governing crack growth. The cycle averaged temperature distribution around the crack tip is obtained from local application of the first law of thermodynamics (i.e., conservation of energy). The analysis leads to the solution of a nonlinear integro-differential equation for crack length as a function of time which is coupled with the local energy equation. A regular perturbation technique is used to obtain an analytical solution which compares very well with experimental results.