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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 955 records · Page 53
All sourcesNASA NTRSDOE OSTI
NASA NTRS1971

Maximum propellant utilization in an electron bombardment thruster

Current theory and experimental data on propellant utilization in electron bombardment ion thrusters are reviewed. Because the majority of investigations have been conducted with mercury, the presentation emphasizes that propellant. The results are presented in as general a form as possible to facilitate use in areas other than space propulsion.

Kaufman, H. R.↗
NASA NTRS1971

Hypersonic bodies of maximum drag for a given lift-to-drag ratio.

The problem considered in this paper is concerned with the aerodynamic design of the forebody shape of reentry vehicles in the blunt, homothetic, elliptic transversal contour, power-law longitudinal contour, raked-off configurational set. In particular, the forebody shape which maximizes the ratio of the forebody pressure drag to the free-stream dynamic pressure for a given lift-to-drag ratio and given geometric properties is determined. This problem is considered because recent survey articles indicate that its solution will provide useful qualitative design information about manned vehicles entering the earth's atmosphere from any of the foreseeable planetary missions. Single-integral equations relating the lift and drag in Newtonian hypersonic flow to the forebody geometry are derived and used to formulate the optimization problem which is solved by a direct numerical method.

Mcmillan, W., III↗
NASA NTRS1971

Maximum temperatures for radiation from plasma waves.

Upper limits to radiation temperatures from plasma waves for emissions near the fundamental and second harmonic of the electron plasma frequency are derived in terms of effective temperature for plasma waves. Results are obtained that differ from those of Melrose (1970) by a factor that can exceed 40,000 for some plasmas.

Smith, D. F.↗
NASA NTRS1971

Maximum propellant utilization in an electron-bombardment thruster.

Current theory and experimental data on propellant utilization in electron-bombardment ion thrusters are reviewed. Because the majority of investigations have been conducted with mercury, the presentation emphasizes that propellant. The results are presented in as general a form as possible to facilitate use in areas other than space propulsion.

Kaufman, H. R.↗
NASA NTRS1972

Interplanetary sector structure at solar maximum.

Extension of Wilcox and Coburn's (1970) previous discussion of the observed interplanetary magnetic sector structure during 1969. A few gaps have been filled in with observations from the magnetometer experiment on Pioneer 9. A comprehensive view of the interplanetary sector structure from 1962 through 1969 is presented and briefly discussed.

Wilcox, J. M.↗
NASA NTRS1972

Spectra of type I supernovae. I - Generalities. II - Interpretation of the spectra of Sn 1960 in NGC 4496 from 8 to 20 days after the maximum of luminosity.

In the late stages of type I supernovae evolution (t greater than 50 days) the spectrum is without doubt an emission line spectrum, but in the early stages it is difficult to tell if an emission line spectrum is observed, or a continuum spectrum modified by the overlaying absorption formed in the outer layers. The mechanism of formation of the observed spectra, the physical conditions in the shell, different possible sources of heating of the shell, identification of the lines, and theoretical computations of the line intensities are discussed. An attempt is made to interpret the set of spectra assuming that a spectrum of widely broadened emission lines truncated by an overlaying absorption is seen. The absorption spectrum is first studied. An identification for the emission lines is proposed, and their intensity on the observed spectra is tentatively estimated. These identifications have to be justified by the theoretical computations of a model of the shell.

Gordon, C.↗
NASA NTRS1973

Digital enhancement of multispectral MSS data for maximum image visibility

A systematic approach to the enhancement of images has been developed. This approach exploits two principal features involved in the observation of images: the properties of human vision and the statistics of the images being observed. The rationale of the enhancement procedure is as follows: in the observation of some features of interest in an image, the range of objective luminance-chrominance values being displayed is generally limited and does not use the whole perceptual range of vision of the observer. The purpose of the enhancement technique is to expand and distort in a systematic way the grey scale values of each of the multispectral bands making up a color composite, to enhance the average visibility of the features being observed.

Algazi, V. R.↗
NASA NTRS1973

Approximation for maximum centerline heating on lifting entry vehicles.

A centerline heating approximation is proposed in which only three basic equations need be solved. The heat rates correlate well with those obtained by more complex procedures. The approximation is readily adaptable to existing trajectory optimization programs to provide realistic surface temperature constraint capability with little increase in computer storage capacity and computer time. It is based on an analysis of heat-rate data computed for altitudes from 36,000 to 122,000 m, velocities from 600 to 7900 m/sec, and angles of attack from 0 to 60 degrees.

Helms, V. T., III↗