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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 487 records · Page 27
All sourcesNASA NTRSDOE OSTI
NASA NTRS1971

Morphological relationships in the chromospheric H-alpha fine structure

A continuous relationship is proposed between the basic elements of the dark fine structure of the quiet and active chromosphere. A progression from chromospheric bushes to fibrils, then to chromospheric threads and active region filaments, and finally to diffuse quiescent filaments, is described. It is shown that the horizontal component of the field on opposite sides of an active region quiescent filament can be in the same direction and closely parallel to the filament axis. Consequently, it is unnecessary to postulate twisted or otherwise complex field configurations to reconcile the support mechanism of filaments with the observed motion along their axis.

Foukal, P.↗
NASA NTRS1972

Heat transfer to four fineness-ratio-1.6 hexagonal prisms with various corner radii at Mach 6

An investigation was conducted in the Langley 20-inch Mach 6 tunnel to define the aerodynamic heat transfer to the radioisotope fuel cask (heat source) of the SNAP-19/Pioneer power system. The shape of the SNAP-19/Pioneer heat source is that of a hexagonal prism with flat ends; the fineness ratio, based on maximum (edge to edge) diameter, is 1.61. Phase-change-paint heat-transfer data and schlieren photographs were obtained on four possible 1/2-scale entry configurations of the SNAP-19/Pioneer heat source. Tests were conducted over a wide range of attitudes and at nominal Reynolds numbers, based on the length of the unablated configuration, of 33,000; 84,000; and 2,200,000.

Hunt, J. L.↗
NASA NTRS1972

Carbon chemistry of Apollo 14 size-fractionated fines.

Experiments have been conducted on several Apollo 12 and 14 samples that confirm the identification of CH4 and C2H6 in lunar fines and breccias. In particular, data for various size fractions of sample 14240,5 are reported which show that the concentrations of these species are dependent on particle size. Results strongly support proposals that solar wind activity is a source of CH4 in lunar samples.

Holland, P. T.↗
NASA NTRS1972

Total emittance of lunar fines.

Description of the technique and discussion of the results of measurements of the total emittance of Apollo 11, 12, and 14 samples of lunar fines. The measurements were performed as a function of temperature upon samples of a density large enough to eliminate any significant density effect on the total emittance.

Birkebak, R. C.↗
NASA NTRS1972

Thermal conductivity of Apollo 12 fines at intermediate density.

The thermal conductivity of an Apollo 12 fines sample (12001,19) was measured under vacuum conditions over a temperature range of 200 to 400 K for a density of 1640 kg/cu m. It was found to vary from approximately .0012 to about .0026 W/m-K. A least-squares curve was found to represent the data satisfactorily.

Cremers, C. J.↗
NASA NTRS1972

The fine structure of slip lines in disordered Cu3Au.

The fine structure of the slip bands observed on the surface of a deformed Cu3Au single crystal is examined. The separation distance determined between the resolved individual slip lines is used to examine the calculations of other authors relating the passing stress of a dislocation past a dislocation pileup on a nearby parallel glide plane.

Salama, K.↗
NASA NTRS1971

Analysis of vegetable seedlings grown in contact with Apollo 14 lunar surface fines.

Chemical analyses and other measurements made on lunar-treated plant seedlings grown for 14 to 21 days demonstrate a direct interaction between germfree plants and lunar material. Treated plants dissolved and absorbed significant quantities of Al, Fe, and Ti from the lunar fines. Cabbage and Brussels sprouts were particularly efficient in the dissolution and absorption of Mn. These results suggested that the beneficial effects observed in the Apollo 11 and 12 quarantine studies might be caused by the uptake of ions from the lunar material.

Charles H. Walkinshaw↗
NASA NTRS1962

Comparison of the Effectiveness of Flares With That of Fins for Stabilizing Low Fineness Ratio Bodies at Mach Numbers From 0.6 to 5.8

An experimental and analytical investigation has been made of the effectiveness of flares and of fins for providing aerodynamic stability of low-fineness-ratio bodies near zero angle of attack. Wind-tunnel tests were performed at Mach numbers from 0.6 to 3.8 to measure the normal force, center of pressure, and drag of bodies consisting of conical noses in combination with cylindrical midsections and finned or flared aftersections. This study included an investigation of the effects of nose bluntness, midbody length, flare angle (from 0° to 20°), and fin leading-edge bluntness. The results showed that for the same plan-form area, flares were more effective than fins, but for the same drag, fins were more effective than flares. Flow separation, which occurred ahead of a flare at certain Mach numbers, resulted in an increase in the stabilizing effectiveness of the flare and a decrease in the drag. However, flow separation led to large undesirable shifts in the center of pressure. Blunt fins were found to be more effective than sharp fins, with the vertical as well as the horizontal fins contributing to the effectiveness. Comparisons of the analytical with the experimental results indicated that the analytical method employed gave good estimates of the stabilizing effectiveness of both fins and flares throughout the supersonic Mach number range.

Leland H Jorgensen↗