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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 217 records · Page 12
All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

Rene 95 brazed joint metallurgical program

This metallurgical program was specifically conducted for the establishment of material properties required for the design of the LF460 fan. The LF460 lift fan is an advanced 18:1 high thrust to weight single stage design. It has a turbine attached to the outer flowpath of the fan blade tip which minimizes the axial depth of the fan. Advanced lightweight attachment designs are employed in this concept to achieve minimum mass polar moments of inertia which are required for good aircraft flight response control. The design features which are unique to this advanced LF460 lift fan are the 0.010 inch thin Udimet 700 alloy integral tip turbine design, minimum weight braze attachment of the turbine to the fan blade, and the high strength and elevated temperature capability of the Rene'95 alloy for the fan blade. The data presented in this report show that the LF460 fan rotor design is feasible and that the design stresses and margins of safety were more than adequate. Prior to any production application, however, additional stress rupture/shear lap joints should be run in order to establish a firm 1200 F stress rupture curve for the CM50 braze metal.

Gay, C.↗
NASA NTRS1972

Internal constitution of Mars.

Models of the internal structure of Mars consistent with the mass, radius and moment of inertia of the planet are constructed. The models assume that the radius of the core is between 0.36 and 0.60 of the radius of the planet, that the zero-pressure density of the mantle is between 3.54 and 3.49 g/cu cm, and that the planet contains 25 to 28% iron. Meteorite models of Mars containing 25 wt % iron and 12 wt % core are also proposed. It is maintained that Mars in contrast to the earth is an incompletely differentiated planet with a core substantially richer in sulfur than the core of the earth. The absence of a magnetic field on Mars is possibly linked with lack of lunar precessional torque and the small size and high resistivity of the Martian core.

Anderson, D. L.↗
NASA NTRS1972

Dynamical characteristics of Phobos and Deimos.

The orbital properties of the two small Martian satellites, Phobos and Deimos, are discussed, as well as those dynamical constants of Mars that can be determined from the satellite orbits. The secular acceleration of the mean motion of Phobos is shown to be very small. Of mechanisms that could cause any such acceleration, only tidal friction appears to be important. From the orbital evolution of the Martian satellites under tidal forces, Phobos and Deimos seem to have originated in nearly circular orbits of low inclination fairly close to the distance at which a satellite's orbital period is the planet's rotation period. It is proposed that the Martian satellites were born at the same time as Mars from equatorial dust clouds. The satellites are predicted to be locked in synchronous rotation, with their axes of minimum moment of inertia pointing on the average toward Mars, whereas their maximum axes are approximately normal to their orbit planes.

Burns, J. A.↗
NASA NTRS1972

Moon model - An offset core.

The lunar model proposed helps to account for the offset of the center of gravity from the center of the optical figure, the moments of inertia of the Moon, the 'mascons,' the localization of the maria basins on the near side of the Moon, the igneous nature of rocks, and the remanent magnetism. In the proposed model the Moon has a core whose center is offset from the center of the outside spheroid towards the earth. Such a core will be formed if the Moon were entirely molten at some time in its past, and on solidification was synchronous with the earth.

Ransford, G.↗
NASA NTRS1972

The composition of the Martian atmosphere - Minor constituents.

The Mariner 6 and 7 infrared spectrometers provided data which, in principle, determine upper limits on the possible atmospheric abundance of every gaseous substance that was undetected but which has recognized absorptions in the accessible spectral region, 1.9 to 14.4 microns. Through supporting laboratory determinations of curves of growth under pressure-broadening conditions appropriate to Mars, upper limits can be specified (expressed first in cm-atm, STP, for a vertical column and then in parts per million) for NO2, NH3, C3O2, SO2, OCS, NO, O3, CH4, N2O, HCL, HBr, and H2S. In addition, considerations of band contours, moments of inertia, and experimental absorption coefficients make it possible to place useful upper limits on 27 additional substances that were not detected and for which curves of growth have not been measured.

Horn, D.↗
NASA NTRS1971

Expendable second stage reusable space shuttle booster. Volume 4: Detail mass properties data

Mass properties data are presented to describe the characteristics of an expendable second stage with a reusable space shuttle booster. The final mass characteristics of the vehicle configurations for three specified payloads are presented in terms of weight, center of gravity, and mass moments of inertia. Three basic subjects are the integrated vehicle system, the expendable second stage, and the booster modifications.

Source record↗
NASA NTRS1973

A movable mass control system to detumble a disabled space vehicle

An internal autonomous control system to either completely detumble a spacecraft or lessen the tumbling motions until the rescue craft arrives is discussed. Such a device would become active upon loss of control. The development of a movable mass control system to convert the tumbling motions of a disabled vehicle into simple spin is presented. A simple spin state would greatly facilitate crew evacuation and final despinning by an external means. The system moves a control mass, according to a selected control law, in the acceleration environment created by the tumbling motion. By moving the mass properly, the rotational kinetic energy of the system may be increased or decreased creating simple spin states about the minimum or maximum moment of inertia axis, respectively. The control system is designed for the latter case due to its associated stability in the presence of perturbing forces.

Edwards, T. L.↗
NASA NTRS1972

Vibration computer programs E13101, E13102, E13104, and E13112 and application to the NERVA program. Project 187: Methodology documentation

Programs for the analyses of the free or forced, undamped vibrations of one or two elastically-coupled lumped parameter teams are presented. Bearing nonlinearities, casing and rotor distributed mass and elasticity, rotor imbalance, forcing functions, gyroscopic moments, rotary inertia, and shear and flexural deformations are all included in the system dynamics analysis. All bearings have nonlinear load displacement characteristics, the solution is achieved by iteration. Rotor imbalances allowed by such considerations as pilot tolerances and runouts as well as bearing clearances (allowing concail or cylindrical whirl) determine the forcing function magnitudes. The computer programs first obtain a solution wherein the bearings are treated as linear springs of given spring rates. Then, based upon the computed bearing reactions, new spring rates are predicted and another solution of the modified system is made. The iteration is continued until the changes to bearing spring rates and bearing reactions become negligibly small.

Mironenko, G.↗
NASA NTRS1972

Some effects of elasticity on lunar rotation

A general Hamiltonian function for a rotating moon in the field of the earth is expanded in terms of parameters orienting the spin angular momentum relative to the principal axes of the moon and relative to coordinate axes fixed in the orbit plane. The effects of elastic distortion are included as modifications of the moment of inertia tensor, where the magnitude of the distortion is parameterized by the Love number k sub 2.

Peale, S. J.↗
NASA NTRS1972

Density of the lunar interior.

It is attempted to derive the constraints that can be placed on the density of the lunar interior. The moment of inertia of the moon and its mean density are being considered in the investigation together with the mass and density of the lunar crust that have been inferred from the seismic refraction data recorded by the passive seismometer. The calculations presented show that the density of the lunar interior can easily approach values as high as 3.5 for a fraction of the lunar mass which lies in the range from 1/2 to 2/3.

Gast, P. W.↗
NASA NTRS1972

Thermal conductivity and resonant multipole interactions.

Investigation of the influence of resonant multipole interactions on exchanges of rotational energy in molecular collisions, by means of a simple two-state impact-parameter approximation. It is found that dipole-quadrupole and quadrupole-quadrupole interactions can have a significant effect for molecules with low moments of inertia.

Nyeland, C.↗
NASA NTRS1973

Venus - Radar determination of gravity potential.

We describe a method for the determination of the gravity potential of Venus from multiple-frequency radar measurements. The method is based on the strong frequency dependence of the absorption of radio waves in Venus' atmosphere. Comparison of the differing radar reflection intensities at several frequencies yields the height of the surface relative to a reference pressure contour; combination with measurements of round-trip echo delays allows the pressure, and hence the gravity potential contour, to be mapped relative to the mean planet radius. Since calibration data from other frequencies are unavailable, the absorption-sensitive Haystack Observatory data have been analyzed under the assumption of uniform surface reflectivity to yield a gravity equipotential contour for the equatorial region and a tentative upper bound of .0006 on the fractional difference of Venus' principal equatorial moments of inertia.

Shapiro, I. I.↗
NASA NTRS1972

Orientation and resonance locks for satellites in the elliptic orbit.

In order to achieve the maximum strength of higher resonance locks for satellites in the elliptic orbit, the condition of satellite orientation during the process of deployment is established. It is shown that for maximum strength locks the axis of the minimum moment of inertia of satellites should point toward the attracting body at plus or minus (5/8) pi and 0 values of the true anomaly f. This condition of deployment is applicable to all cases of resonance rotation regardless of the value of lock number k and orbit eccentricity e.

Liu, H.-S.↗
NASA NTRS1973

Gravity field of Mars from Mariner 9 tracking data.

Further reduction of Doppler tracking data from Mariner 9 confirms our earlier conclusion that the gravity field of Mars is considerably rougher than the fields of either the earth or the moon. The largest positive gravity anomaly uncovered is in the Tharsis region which is also topographically high and geologically unusual. The value obtained for the inverse mass of Mars is in good agreement with prior determinations from Mariner fly by trajectories. The direction found for the rotational pole of Mars is in excellent agreement with Sinclair's recent value, determined from earth-based observations of Mars' satellites. Other important physical constants that have either been refined or confirmed by the Mariner 9 data include: (1) the dynamical flattening, (2) the maximum principal moment of inertia, and (3) the period of precession of Mars' pole.

Lorell, J.↗
NASA NTRS1973

Lunar evolution - How well do we know it now.

The currently known astronomical, chemical, and magnetic data are not uniquely indicative of an extensively and globally molten moon. It is argued that an accretional layering occurred in the moon, but at temperatures below solidus. The excess mass in the near side of the moon compatible with a 2-km displacement in the center of mass relative to the center of figure and the moment of inertia data is considered to be due to Fe-FeS liquid formation and inhomogeneous segregation. These Fe-FeS bodies, termed 'fescons,' are shown to be capable of accounting for the presently available magnetization data, by acting as small regenerative dynamos with a time-stability less than that of the terrestrial equivalent. The chemical characteristics of the highly differentiated materials, are considered to be due to small-scale localized melting caused by collisional events, from sources in which accessory phases play a significant role. Mare basalts are considered to be melts in the overlying material produced at a later time by K-40 radioactivity in the fescons. Some consequences of the present hypothesis are suggested. It is concluded that these and other characteristics of the lunar materials are reconcilable with a 'cold' moon, such as discussed by Urey over the past two decades.

Murthy, V. R.↗
NASA NTRS1973

The composition and origin of the moon.

Many of the properties of the moon can be explained by early condensation processes in the solar nebula. Thermodynamic calculations show that Ca-, Al- and Ti-rich compounds condense first in a cooling nebula. The inital high-temperature mineralogy is gehlenite, spinel, perovskite, (Ca-Al)-rich pyroxenes and anorthite. Inclusions in type III carbonaceous chondrites such as the Allende meteorite are composed primarily of these minerals and are highly enriched in trace refractories such as REE relative to carbonaceous chondrites. These inclusions can yield basalt and anorthosite in the proportions required to eliminate the europium anomaly, leaving a residual spinel-melilite interior. A high-(Ca-Al) deep interior does not imply an unacceptable mean density of moment of inertia for the moon. The inferred high-U content of the lunar interior, both from the Allende analogy and the high heat flow, indicates a high-temperature interior. The model is consistent with extensive early melting, shallow melting at 3 AE, and with presently high deep internal temperatures.

Anderson, D. L.↗
NASA NTRS1973

Mass property control of a synchronous meteorological satellite scanning experiment.

A scanning mirror assembly which is part of a Synchronous Orbit Meteorological Satellite is an example where mission objectives required measurement and control of weight, mass center, principal moments of inertia, and products of inertia. The scanning mirror oscillates within the spin stabilized spacecraft, and both the scanning motor torque and perturbation of spacecraft attitude and spin rate have to be reduced to low levels. A theoretically ideal solution would be to make the mirror inertia constant about all axes in a plane perpendicular to the oscillation axis. A practically attainable compromise is to locate principal axes preferentially and make the difference between two of them acceptably small. Methods for making the necessary mass property measurements and deriving and applying minimum weight ballast correction to achieve the necessary mass distribution are discussed. It is noted that mass property control operations are typically subject to practical constraints such as geometry and functional operation of the system and capability of available measurement facilities and fixtures.

Lang, W. E.↗
NASA NTRS1973

Compilation, design tests: Energetic particles Satellite S-3 including design tests for S-3A, S-3B and S-3C

A compilation of engineering design tests which were conducted in support of the Energetic Particle Satellite S-3, S-3A, and S-3b programs. The purpose for conducting the tests was to determine the adequacy and reliability of the Energetic Particles Series of satellites designs. The various tests consisted of: (1) moments of inertia, (2) functional reliability, (3) component and structural integrity, (4) initiators and explosives tests, and (5) acceptance tests.

Ledoux, F. N.↗