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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 1,405 records · Page 78
All sourcesNASA NTRSDOE OSTI
NASA NTRS1973

Direct Observations of the Charge States of Low Energy Solar Particles

The charge states of carbon and oxygen of solar origin were measured directly in interplanetary space. At 100 keV per nucleon the C(+5)/C(+6) and O(+7)/O(+8) ratios are 1.8 and 1.6 respectively. It was found that the abundance ratios of low energy heavy nuclei to He is significantly larger than corresponding photospheric values: the enhancement of O/He is 35 and both Si/He and Fe/He are overabundant by a factor of 100. To explain these observations a mechanism is proposed which first preferentially accelerates heavy ions and is followed by either storage of these ions in the coronal regions or strong adiabatic deceleration.

Gloeckler, G.↗
NASA NTRS1972

Momentum transfer interaction of a laser-produced plasma with a low-pressure background.

The expansion of a laser-produced metallic plasma into a photoionized hydrogen background has been experimentally studied. Langmuir probe and microwave diagnostics have detected an interaction front which decelerates with a dependence on background density and time consistent with a momentum coupling between the laser plasma and the ionized fraction of the background. An ion percursor has also been observed. Calculations of scattering cross sections indicate that multiple-encounter Coulomb scattering will dominate collisional momentum transfer. The leading edge of the laser plasma contains multiply charged ions of charge state z greater than or equal to 5, and collisional effects appear adequate to explain the principal features of the momentum coupling. The ion precursor may have a collisionless origin.

Koopman, D. W.↗
NASA NTRS1972

Galactic cosmic ray modulation from 1965-1970.

Numerical solutions of the cosmic-ray equation of transport within the solar cavity and including the effects of diffusion, convection, and energy losses due to adiabatic deceleration, have been used to reproduce the modulation of galactic electrons, protons, and helium nuclei observed during the period from 1965 to 1970. Kinetic energies between 10 and 10,000 MeV/nucleon are considered. Computed and observed spectra are given for the years 1965, 1968, 1969, and 1970 together with the diffusion coefficients. These diffusion coefficients are assumed to be of separable form in rigidity and radial dependence, and are consistent with the available magnetic-field power spectra. The force-field solutions are given for these diffusion coefficients and galactic spectra and are compared with the numerical solutions. It is shown that the energy losses and convection lead to near-earth nuclei spectra at kinetic energies less than or equal to 100 MeV/nucleon in which the differential intensity is proportional to the kinetic energy with little dependence on the form of the galactic spectrum. This dependence is in agreement with the observed spectra of all species of atomic nuclei and it is argued that this provides strong observational evidence for the presence of energy losses in the propagation process, and for the exclusion of low-energy galactic nuclei from near earth.

Urch, I. H.↗
NASA NTRS1973

Observational constraints imposed by Brans-Dicke cosmologies.

Flat-space Brans-Dicke (BD) cosmologies previously found are analyzed in more detail. It is shown that the observed values of the matter density, the Hubble age, the ages of objects in the universe, the deceleration parameter, and the bound on the (unobserved) fractional time variation of the gravitational constant are too inaccurate to distinguish between the BD and Einstein-Friedmann cosmologies. An attempt is made to argue that because of the great degree of latitude in the observational constraints imposed by the BD cosmologies, efforts to improve the bound on the fractional time variation of G alone are not sufficient to rule out the BD theory.

Morganstern, R. E.↗
NASA NTRS1973

Evaluation of glide paths for landing a VTOL airplane using linear regulator theory.

A method of evaluating certain characteristics of approach paths for VTOL airplanes is presented which is based on the solution of the matrix Riccati equation to obtain an optimal state variable feedback controller. The longitudinal equations of motion of the airplane are linearized about a preselected path and the resulting system of equations is treated as a linear, time-varying regulator. The controller which minimizes a quadratic cost function is applied to the linearized system to determine the airplane's ability to return to the prescribed path given a specified initial error in altitude. The procedure is applied to the XC-142A, tilt-wing, V/STOL airplane, under decelerating approach conditions with a glide path consisting of two segments, the first having a smaller angle of descent than the second.

Reid, G. F.↗
NASA NTRS1973

The Viking mortar - Design, development, and flight qualification.

Approximately 25,400 ft above the local surface of Mars, a radar height sensor fires the Viking mortar, which ejects a 53-ft D sub o disk-gap-band (DGB) parachute. The parachute decelerates and stabilizes the Viking lander sufficiently for the terminal engine system to take over and effect a soft landing. The general design and environmental requirements for the mortar system are presented; various illustrations of the mortar components and how the mortar system functions also are presented. Primary emphasis is placed on manufacturing, developing, and qualification testing of the mortar system.

Brecht, J. P.↗
NASA NTRS1973

Parachute mortar design.

Mortars are used as one method for ejecting parachutes into the airstream to decelerate spacecraft and aircraft pilot escape modules and to effect spin recovery of the aircraft. An approach to design of mortars in the class that can accommodate parachutes in the 20- to 55-foot-diameter size is presented. Parachute deployment considerations are discussed. Comments are made on the design of a power unit, mortar tube, cover, and sabot. Propellant selection and breech characteristics and size are discussed. A method of estimating hardware weights and reaction load is presented. In addition, some aspects of erodible orifices are given as well as comments concerning ambient effects on performance. This paper collates data and experience from design and flight qualification of four mortar systems, and provides pertinent estimations that should be of interest on programs considering parachute deployment.

Pleasants, J. E.↗
NASA NTRS1973

Preliminary analysis of NASA optical data obtained in barium ion cloud experiment of September 21, 1971.

This paper reviews the optical data obtained by NASA in the joint NASA-MPE experiment conducted on September 21, 1971, involving the release of a barium cloud at an altitude of about 31,500 km over Colombia, South America. The data indicated an anomalously high rate of elongation and an unexpectedly large rate of deceleration of the main core of the ion cloud. The outermost striational features achieved a steady velocity within a few minutes, thus indicating that they had acquired the velocity of the ambient plasma. From the observed drift of these striations, one deduces an electric field that, when referred to a coordinate system rotating with the earth, has a meridional component directed toward the interior of the magnetic loop of 0.14 mV/m and a component perpendicular to the meridional plane of 0.15 mV/m directed to the west.

Adamson, D.↗
NASA NTRS1973

Automatic control of a helicopter with a hanging load

An autopilot logic is designed here for controlling a helicopter with a hanging load. A 16th order model for the system is decoupled into four subsystems: (1) a second order system for yawing motion, (2) a second order system for vertical motion, (3) a sixth order system for longitudinal motion, and (4) a sixth order system for lateral motion. A measuring scheme, which could be used in remote areas, is developed and filters are designed to estimate the state variables from these measurements. The autopilot can be used to move the load over short distances without retracting the cables. This is done by automatically shifting the autopilot modes from position-hold (hover) to acceleration-hold to velocity-hold (cruise) to deceleration-hold to velocity-hold (near hover) to position-hold (hover). Use of such an autopilot might save considerable turnaround time. The Sikorsky S-61 helicopter is chosen as an example vehicle. The performance of the controlled system is studied in the presence of longitudinal and lateral winds.

Gupta, N. K.↗
NASA NTRS1973

Effect of artificial gravity on thermoregulation, respiratory metabolism and intermediary metabolism of animals

Metabolic alterations in animals exposed to radial acceleration are reported. Temperatures in acutely stressed animals dropped profoundly in correlation with decreased food consumption. Repeated exposure of the acutely stressed animal caused a decrease in hypothermic response whereas deceleration or reduction of G load did not significantly change body temperatures. Adrenal corticosteroids affected significantly the animal's recovery rate. No changes occured in body temperature patterns of chronically centrifuged animals after full adaptation; their respiratory rate increased very significantly in terms of CO2 output as did their glucose uptake by muscle tissues and their insulin responsiveness or sensitivity.

Oyama, J.↗
NASA NTRS1973

Motion of metric type 4 radio sources and its relation to shock waves responsible for type 2 radio bursts

The relation of the motion of type 4mA sources with shock waves responsible for type 2 bursts were considered using the observed data for these two radio sources. The difference of the emission mechanism between type 2 and type 4mA bursts suggest that the moving speed of the shock waves mentioned above is not necessarily equal to the metric type 4 sources. By analyzing the observed data on the speeds for both type 2 and type 4 sources., it was found that type 4 bursts decelerate and often cease to move in the solar envelop and that type 2 sources move at higher speeds than type 4 sources.

Sakurai, K.↗
NASA NTRS1973

Design of a flight director/configuration management system for piloted STOL approaches

The design and characteristics of a flight director for V/STOL aircraft are discussed. A configuration management system for piloted STOL approaches is described. The individual components of the overall system designed to reduce pilot workload to an acceptable level during curved, decelerating, and descending STOL approaches are defined. The application of the system to augmentor wing aircraft is analyzed. System performance checks and piloted evaluations were conducted on a flight simulator and the results are summarized.

Hoh, R. H.↗
NASA NTRS1973

A lower limit to the altitude of coronal particle storage regions deduced from solar proton energy spectra

The spectrum of low energy protons observed at 1 AU following solar flares shows little or no evidence of energy degradation down to approximately 0.3 MeV. Such observations may be used to set a lower limit on the altitude of hypothetical coronal particle storage regions, ranging from 2 to 7 R sub s. It is pointed out that closed coronal magnetic loop structures are observed to extend to 2R sub s, so that long-term storage of low energy protons does not take place in the immediate vicinity of the sun. It is further suggested that in the few cases where the proton spectrum appears to be degraded at low energies, the energy loss may be due to adiabatic deceleration in the expanding solar wind. The alternative of continual acceleration is suggested as a plausible substitute for the particle storage hypothesis.

Krimigis, S. M.↗
NASA NTRS1974

Preliminary study of a possible automatic landing system

Navigation and control laws for a possible automatic landing system have been investigated. The system makes use of data from an inertial table and either an airborne or ground radar to generate signals that guide the airplane to a landing. All landing maneuvers take place within a zone that extends 6000 m out from the touchdown point, 4000 m on each side of the runway center line, and 540 m high. The results show that the system can adequately control the airplane on steep, curved decelerating approaches to a landing that takes place with small errors from the desired landing point and desired airplane attitude. The system studied would interface well with the scanning beam microwave landing system (MLS). The use of this system with the MLS makes it possible to incorporate an independent landing monitor.

Sherman, W. L.↗
NASA NTRS1973

Systems design study of the Pioneer Venus spacecraft. Volume 1. Technical analyses and tradeoffs, section 7 (part 3 of 4)

The aerodynamic design problems for the Pioneer Venus mission are discussed for a small probe shape that enters the atmosphere, and exhibits good stability for the subsonic portion of the flight. The problems discussed include: heat shield, structures and mechanisms, thermal control, decelerator, probe communication, data handling and command, and electric power.

Source record↗
NASA NTRS1973

Ion time-of-flight determinations of doubly to singly ionized mercury ion ratios from a mercury electron bombardment discharge

Doubly to singly charged mercury ion ratios in electron bombardment ion thruster exhaust beams have been determined as functions of bombardment discharge potential, thrust beam current, thrust beam radial position, acceleration-deceleration voltage ratio, and propellant utilization fraction. A mathematical model for two-step ionization processes has been derived, and calculated ion ratios are compared to observed ratios. Production of Hg(++) appears to result primarily from sequential ionization of Hg(+) in the discharge. Experimental and analytical results are presented, and design, construction, and operation features of an electrostatic deflection ion time-of-flight analyzer for the determination of the above-mentioned ratios are reviewed.

Sellen, J. M., Jr.↗
NASA NTRS1973

The Viking Mission

The Viking Mission is a scientific exploration of the planet Mars with particular emphasis on the search for life. Two unmanned spacecraft will be launched from Cape Kennedy in 1975 and will arrive at Mars in the summer of 1976. Each spacecraft will consist of an orbiter and lander. The landing sites will be preselected before launch and certified by orbital reconnaissance before landing. Soft landing on the surface will be accomplished by decelerating first on an aeroshell, then a deployed parachute and finally using terminal propulsion engines. Thirteen investigations will be performed, including mapping experiments from the orbiter, and analytical experiments on the surface which deal broadly with the biology, geosciences and atmospheric characteristics of the planet.

Martin, J. S., Jr.↗