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At least 1,657 records · Page 92
All sourcesNASA NTRSDOE OSTI
NASA NTRS1977

Some petrological aspects of Imbrium stratigraphy

Descriptions are given of the petrochemistry of two Apennine Front breccias, both ejected to the surface during excavation of Spur Crater. The first clast type is breccia number 15445, a spinel pyroxenite whose mineralogy and petrochemistry are consistent with the original rock type being a garnet pyroxenite. The second rock, breccia 15459, is plutonic norite, in which coarsely exsolved inverted pigeonite is associated with anorthitic plagioclase. Application of mineral geothermometers indicates crystallization of these rocks below 1100 C; hence their textures probably developed largely by solid state recrystallization during impact-metamorphism.

Ridley, W. I.↗
NASA NTRS1977

The promise of air cargo-system aspects and vehicle design

A review of the current operation of the air cargo system is presented and the prospects for the future are discussed. Attention is given to air cargo demand forecasts, the economics of air cargo transport, the development of an integrated air cargo system, and the evolution of airfreighter design. Particular emphasis is placed on the span-distributed load concept, examining the Boeing, Douglas, and Lockheed spanloaders.

Whitehead, A. H., Jr.↗
NASA NTRS1977

Theoretical aspects of tidal and planetary wave propagation at thermospheric heights

A simple semiquantitative model is presented which allows analytic solutions of tidal and planetary wave propagation at thermospheric heights. This model is based on perturbation approximation and mode separation. The effects of viscosity and heat conduction are parameterized by Rayleigh friction and Newtonian cooling. Because of this simplicity, one gains a clear physical insight into basic features of atmospheric wave propagation. In particular, we discuss the meridional structures of pressure and horizontal wind (the solutions of Laplace's equation) and their modification due to dissipative effects at thermospheric heights. Furthermore, we solve the equations governing the height structure of the wave modes and arrive at a very simple asymptotic solution valid in the upper part of the thermosphere. That 'system transfer function' of the thermosphere allows one to estimate immediately the reaction of the thermospheric wave mode parameters such as pressure, temperature, and winds to an external heat source of arbitrary temporal and spatial distribution. Finally, the diffusion effects of the minor constituents due to the global wind circulation are discussed, and some results of numerical calculations are presented.

Volland, H.↗
NASA NTRS1976

Chemical aspects of agglutinate formation - Relationships between agglutinate composition and the composition of the bulk soil

Attention is centered on the nature and intensity of geochemical fractionation accompanying agglutination of several size fractions of the immature Apollo-16 soil sample 67460, from North Ray Crater. The soil features coarse mean grain size about 150 microns, low (20 wt.%) magnetic agglutinate content, and a bimodal grain size distribution. The magnetic fraction included both agglutinates and magnetic non-agglutinates (glass-free microbreccias with 30-60 micron native FeNi grains hosted in a matrix of pyroxene, ilmenite, and olivine). The separation process residue contained nonmagnetic agglutinates with compositions near pure plagioclase. The magnetic agglutinate fraction appears selectively enriched in ferromagnesian elements to the partial exclusion of plagioclase elements. Agglutinate glass chemistry based solely on magnetic separation is deprecated on the basis of the results.

Via, W. N.↗
NASA NTRS1976

Material development aspects of an oxidation protection system for a reinforced carbon-carbon composite

The paper describes the procedures which led to selection of a diffusion-coated siliconized oxidation-resistant reinforced carbon-carbon composite as a candidate for use in the leading edge structure of the Space Shuttle for the purpose of providing thermal protection. Materials were evaluated on the basis of oxidation-inhibitor performance, strength properties, and fabricability. Compounds of titanium, tantalum, zirconium, silicon, hafnium, aluminum, and boron were compounded with the reinforced carbon-carbon material in two different processing techniques to discover an oxidation-inhibited system which provided multicycle protection at temperatures up to 4000 F. Details of the manufacture and testing of the reinforced carbon-carbon composites are provided.

Rogers, D. C.↗
NASA NTRS1977

Performance and safety aspects of the XV-15 tilt rotor research aircraft

Aircraft performance is presented illustrating the flexibility and capability of the XV-15 to conduct its planned proof-of-concept flight research in the areas of dynamics, stability and control, and aerodynamics. Additionally, the aircraft will demonstrate mission-type performance typical of future operational aircraft. The aircraft design is described and discussed with emphasis on the safety and fail-operate features of the aircraft and its systems. Two or more levels of redundancy are provided in the dc and ac electrical systems, hydraulics, conversion, flaps, landing gear extension, SCAS, and force-feel. RPM is maintained by a hydro-electrical blade pitch governor that consists of a primary and standby governor with a cockpit wheel control for manual backup. The two engines are interconnected for operation on a single engine. In the event of total loss of power, the aircraft can enter autorotation starting from the airplane as well as the helicopter mode of flight.

Wernicke, K. G.↗
NASA NTRS1976

Solar cycle review /General aspects/

Several topics are discussed in this review of the solar cycle. The basic solar-interplanetary magnetic structure is considered, and the high speed solar wind streams and their sunspot cycle variation are described, with attention to the sunspot cycle variation, the high speed solar wind streams and geomagnetic disturbances, and the causes of changes of the north-south component of the interplanetary magnetic field. Solar storms, solar flares, and magnetic bubbles are examined with attention directed to the solar cycle variation of transient polar activities and the interplanetary disturbances associated with solar storms. Some features of cosmic rays, the 11-year cycle variation and the Forbush decreases, are considered. Attention is also directed to the terrestrial atmosphere and to the outer planets and their relation to the solar cycle.

Akasofu, S.-I.↗
NASA NTRS1977

An unusual aspect of solar wind speed variations during solar cycle 20

Geomagnetic records from 1868 through 1975 indicate that geomagnetic activity during 1973-1975 was unusually enhanced for that phase of the sunspot cycle (5-7 years after solar maximum). Previous work indicates that long-term variations in geomagnetic activity are closely coupled to long-term variations in the bulk flow speed of the solar wind. Thus, it is inferred that reported averages of the solar-wind speed for the 1973-1975 era are unusually large for that phase of the sunspot cycle.

Gosling, J. T.↗
NASA NTRS1977

Aerodynamics of a finite aspect ratio jet flap at low flight speeds

A theoretical treatment of inviscid incompressible flow over a thin wing equipped with a part-span jet flap is given; the treatment is capable of describing low-speed flight regimes where nonlinear problems may be significant. The induced flow fields of the jet and the wing are characterized separately, and a fully coupled solution is reached through iteration. A lifting surface theory is employed for the wing aerodynamics, and the vorticity associated with the jet is also taken into account. Calculations are presented for the case of a rectangular wing. Comparisons with existing linear or nonlinear theories and experimental data suggest that the treatment is capable of accurate analyses in situations involving small angles of attack, jet deflection angles and jet momentum coefficients. In addition, the theory may be a better means of evaluating subsidiary aerodynamic variables, such as downwash aft of the wing, than existing treatments.

Addessio, F. L.↗
NASA NTRS1976

Producibility aspects of advanced composites for an L-1011 Aileron

The design of advanced composite aileron suitable for long-term service on transport aircraft includes Kevlar 49 fabric skins on honeycomb sandwich covers, hybrid graphite/Kevlar 49 ribs and spars, and graphite/epoxy fittings. Weight and cost savings of 28 and 20 percent, respectively, are predicted by comparison with the production metallic aileron. The structural integrity of the design has been substantiated by analysis and static tests of subcomponents. The producibility considerations played a key role in the selection of design concepts with potential for low-cost production. Simplicity in fabrication is a major factor in achieving low cost using advanced tooling and manufacturing methods such as net molding to size, draping, forming broadgoods, and cocuring components. A broadgoods dispensing machine capable of handling unidirectional and bidirectional prepreg materials in widths ranging from 12 to 42 inches is used for rapid layup of component kits and covers. Existing large autoclaves, platen presses, and shop facilities are fully exploited.

Van Hamersveld, J.↗
NASA NTRS1977

Practical aspects of sonic boom problems

SST configurations selected from the point of minimizing sonic booms are investigated. It is indicated that for a total length of 300 ft and total initial weight of the same order as the present U.S. SST designs, sonic booms having shock pressure rise of the order of 0.6 lb/square foot can be obtained. Values as low as 0.3 are possible for airplanes designed for cross-country flights.

Ferri, A.↗
NASA NTRS1977

System aspects of spacecraft charging

Satellites come in a variety of sizes and configurations including spinning satellites and three-axis stabilized satellites. All of these characteristics have a significant effect on spacecraft charging considerations. There are, however, certain fundamentals which can be considered which indicate the nature and extent of the problem. The global positioning system satellite serves to illustrate certain characteristics.

Bower, S. P.↗
NASA NTRS1977

Some aspects of the inversion problem in remote sensing

Several commonly used methods for inversion--constrained linear inversion, synthesis (Backus-Gilbert) methods and nonlinear iterative techniques for the Chahine type--are discussed. It is demonstrated that a very close connection exists between Backus-Gilbert solutions and those given by constrained linear inversion. A number of examples of the application of such methods are presented, showing that resolution is not greatly different for quite different algorithms, a result quite in accord with general theoretical considerations: more resolution can be achieved at the expense of introducing greater a priori bias in the procedure.

Twomey, S.↗
NASA NTRS1977

Land utilization and ecological aspects in the Sylhet-Mymensingh Haor Region of Bangladesh: An analysis of LANDSAT data

The use of remote sensing data from LANDSAT (ERTS) imageries in identifying, evaluating and mapping land use patterns of the Haor area in Bangladesh was investigated. Selected cloud free imageries of the area for the period 1972-75 were studied. Imageries in bands 4, 5 and 7 were mostly used. The method of analysis involved utilization of both human and computer services of information from ground, aerial photographs taken during this period and space imageries.

Chowdhury, M. I.↗
NASA NTRS1977

Certain aspects of the vestibular problem in space medicine

Vestibulovegetative disorders on manned space flights are discussed. A study relating to the vestibular stimuli in respiration, diaphoresis cardiac rhythm and a broad complex of hemodynamic indices was conducted. Certain tests for astronaut candidates are discussed.

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