SEARCH · Engineering Papers
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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Five new aluminum lines in the region from 35 to 50 A have been produced by focusing the radiation of a 460-MW, Q-spoiled ruby laser on an aluminum target. Characteristics of the new lines, including their observed and predicted wavelength, intensity, and transition, are tabulated.
Accuracy tests have been made of the approximation, proposed recently by Wang (1971), which reduces the computation of three-dimensional, laminar, compressible, boundary-layer equations to the problem of solving two-dimensional type boundary-layer equations. The tests were made by a comparison of the results achieved using Wang's method with a fully three-dimensional boundary-layer calculation. Results of the comparison are tabulated and are found to be in good agreement.
Exploration of available information concerning carbon on the moon, following review of what is known about carbon on the earth, and consideration of the results of studies of meteorites, which have provided the first direct clues about extraterrestrial carbon. Carbon and carbon isotope composition data taken from Apollo 11 samples are tabulated. Carbon compounds produced by pyrolysis, extracted with benzene-methanol, extracted with water, and freed by acid treatment are discussed. Carbon and carbon compounds in lunar rocks and soils appear to be distributed heterogeneously.
An analysis has been made of four small samples of material brought to earth by the Luna 16 mission, with the aim to determine rare earths and other trace elements in these samples. The analytical results are tabulated, and the rare earth abundances are compared with the average for chondrites. A comparison is also made with the results of similar analyses of Apollo samples.
Investigation of the effects of sensor spatial resolution on estimating the amount of clouds covering the earth by simulating various cloud distributions and sizes, and measuring the known cloud amount with resolution of different sizes using a cloud-no cloud threshold technique often applied in automatic data processing. Cloud amount statistics have been tabulated for a three-orders-of-magnitude range in the ratio (R) of areal cloud size to areal resolution size for seven cloud amounts between 6 and 90%. Three different cloud patterns were used. These were 1) a regularly spaced pattern of homogeneous dots arranged in rows and columns (to simulate cloud streets), 2) a randomly spaced pattern of the same dots (to simulate randomly oriented cumulus clouds), and 3) a heterogeneous cloud size distribution irregularly spaced (to simulate a view of different cloud types and sizes). Two cloud amount estimation techniques were tested. Cloud amounts of 100% (method 1) and 50% (method 2) were assigned to partially filled resolution elements. Using criteria applicable to some studies carried out in the past, it is shown that cloud amount estimations can be in error by as much as 86 and 38%, respectively, for the two methods. Nomograms have been developed which subtantially improve the estimate of the true cloud cover for R less than 100, provided that R can be determined.
A tabulation of calculated rotational line intensities, relative to the integrated intensity of a vibration-rotation band, is given for Sigma-Sigma, Pi-Sigma, Sigma-Pi, Pi-Pi, and Delta-Pi transitions of nitrous oxide. These calculations were made for temperatures of 250 K and 300 K. A summary of band-intensity measurements is also presented.
The ratio of intensities of hydrogen Balmer lines H-alpha/H-beta is proposed as an indicator of electron temperature in a nonequilibrium plasma. Although different from the equilibrium case, the intensity ratio is a unique function of electron temperature provided that the optical depth is small for the visible lines and the plasma is far out of equilibrium. For such a plasma, the H-alpha/H-beta intensity ratios are computed. The results are tabulated in the form of a conversion table between the measured excitation temperature and the true electron temperature. The ranges of applicability of the conversion table are also computed and are presented in separate tables. An example is shown in which particle densities are consistent with the Saha equilibrium condition at the apparent excitation temperature even though the plasma is in nonequilibrium at a different true electron temperature.
A flowing afterglow has been used to produce metastable He(2 super 3 S). It is shown that when He(2 super 3 S) interacts with a diatomic or triatomic molecule, its electronic excitation energy can be transferred to electronic and vibrational excitation of the molecule. To examine this mechanism, the rates for the production of electronically excited molecules, observed spectroscopically between 190 and 750 nm in the reaction of He(2 super 3 S) with CO2, have been measured. Results are tabulated.
A core model, consisting of a (12-4) central potential displaced from the origin, is suggested as a representation of the interaction of polyatomic ions with neutral molecules. The diffusion collision integral, which describes ion mobility, is computed and tabulated as a function of temperature and core size. The addition of the core reduces the maximum in the mobility against temperature curve, and eventually reduces the mobility below its polarization limit at all temperatures. These results are in accord with limited available experimental data. Comparison is made with other models of ion-neutral interactions.
Absolute excitation functions were measured for the NO(+) A l super Pi-Chi 1 super Sigma (+) molecular band system, the nitrogen 1200-, 1243-, and 1493-A multiplets, and oxygen 1304-A multiplet. Excitation was by electron impact on NO from threshold to approximately 250 eV. Results are plotted and tabulated.
The need for further development and reevaluation of current space-vehicle materials (intended for a single mission) to meet the long-time requirements of a space shuttle is demonstrated. Leading metallic material candidates and their properties are tabulated for a delta-wing space shuttle configuration with a metallic thermal protection system.
In order to provide insight for the selection of attitude- and stationkeeping propulsion systems for future communications satellites, current auxiliary-propulsion systems are surveyed. Thruster systems specifically considered are stored gas, vaporizing ammonia/electrothermal, catalytic monopropellant hydrazine, electrothermal monopropellant hydrazine, plenum monopropellant hydrazine, ion, colloid, and pulsed plasma. Each of the thruster types is discussed in three sections: (1) description of thruster system and how it functions, (2) space flight experience, and (3) survey of state-of-the-art thrusters. In addition, a qualitative tabulation of thruster characteristics is included.
By analyzing all existing frequency data of the oxygen molecule in microwave, submillimeter, and infrared spectroscopy, a new set of molecular parameters is obtained. The parameters are tabulated and compared with values obtained by other authors. Observed and calculated frequencies of oxygen lines are also given.
Results of a systematic search for bright nebulae that are likely to be emission regions in the vicinity of high-velocity gas, drawing attention to some interesting coincidences that have been found. It is apparent that there is a tendency for many of the high-latitude nebulae to cluster in the vicinity of the high-velocity gas. Some of the most prominent cases of overlap are tabulated. It is emphasized that measurement of the radial velocity of the emission nebulae could confirm the existence of a physical association between high-latitude emission nebulae and high-velocity gas. The fact that Johnson (1972) had used narrow-band filters to find indications of H beta emission in similar high-latitude nebulae suggests that H alpha should readily be detectable with Fabry-Perot interferometry.
Calculated spectral line profiles (intensity distributions) of the helium triplet diffuse series were obtained using the quasi-static approximation for ions and electrons. In these calculations, Doppler broadening, although negligible in most of the cases, was included as a device to avoid singularities. Plots and tabulations of the calculated profiles are presented, in addition to a discussion of the computational procedure and the validity of the calculations.
A description of the performance test to compare noise output from a quiet engine with acoustic nacelle to the noise output of the JT3D turbofan engine is presented. Tabulations depict comparative thrusts, bypass ratios, core jet velocities, and fan jet velocities for both engines during simulated takeoff and approach performances.
Available information on weight and inertia, aerodynamic derivatives, control characteristics, and stability augmentation systems is documented for 10 representative contemporary airplanes. Data sources are given for each airplane. Flight envelopes are presented and dimensional derivatives, transfer functions for control inputs, and several selected handling qualities parameters have been computed and are tabulated for 10 different flight conditions including the power approach configuration. The airplanes documented are the NT-33A, F-104A, F-4C, X-15, HL-10, Jetstar, CV-880M, B-747, C-5A, and XB-70A.
The evaluation is discussed of the terminal sterilization process for unmanned lander spacecraft. Results of biochemical test deviations encountered with the identification schemes are tabulated. Studies to examine the possibility of shifts in biochemical reaction patterns during storage and subculture of the environmental Bacillius isolates are also reported.