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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 631 records · Page 35
All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

Solar large-scale positive polarity magnetic fields and geomagnetic disturbances

Unlike the negative polarity solar magnetic field large-scale regular features that correlate with enhanced solar activity regions, the positive polarity regular formations formed in the weak and old background magnetic fields seem to correlate well with geomagnetically enhanced periods of time (shifted for 4 days), which means that they seem to be the source of the quiet solar wind. This behavior of the large intervals of heliographic longitude with prevailing positive polarity fields may be followed to the end of the 18th cycle, during the declining part of the 19th cycle, and during the first half of the present 20th cycle of solar activity.

Bumba, V.↗
NASA NTRS1973

Position determination accuracy from the microwave landing system

Analysis and results are given for the position determination accuracy obtainable from the microwave landing guidance system. Siting arrangements, coverage volumes, and accuracy standards for the azimuth, elevation, and range functions of the microwave system are discussed. Results are given for the complete coverage of the systems and are related to flight operational requirements for position estimation during flare, glide slope, and general terminal area approaches. Range rate estimation from range data is also analyzed. The distance measuring equipment accuracy required to meet the range rate estimation standards is determined, and a method of optimizing the range rate estimate is also given.

Cicolani, L. S.↗
NASA NTRS1972

An experiment to determine the relative positions of two collocated laser tracking stations

Two Goddard Space Flight Center laser tracking stations were collocated for a short time towards the end of 1971 for the purposes of comparing their tracking performance and quality. The lasers, only 25 meters apart, obtained simultaneous tracking data on eighteen passes of the Beacon Explorer C spacecraft. These data have now been used to determine the location of one laser with respect to the other with the result that the computed position of the second laser agrees with the surveyed position to 4 centimeters in latitude and height, and 1 centimeter in longitude.

Dunn, P. J.↗
NASA NTRS1973

Performance comparison of three normal-shock position sensors for mixed-compression inlets

The performance of three types of normal shock position sensors for supersonic inlets is described. All three sensors determined the shock position from the presence of the large pressure gradient at the normal shock location. The logic means for the three sensors were: (1) electronic, using pressure transducers, (2) fluidic, and (3) direct-coupled pressure switches. The sensors were evaluated in a two-dimensional, Mach 2.7, supersonic inlet having 30-percent internal supersonic area contraction. Both dynamic (from 1 to 80 Hz) and static tests were conducted.

Dustin, M. O.↗
NASA NTRS1973

An experimental evaluation of metallic diaphragms for positive fuel expulsion in the Atmosphere Explorer, hydrazine propulsion subsystem

Four Arde conospheroid metallic diaphragms were tested at NASA to evaluate their capability for use in the orbit adjust propulsion subsystem (OAPS) of the Atmosphere Explorer spacecraft (AE's C, D, and E). The diaphragms will be used for positive propellant expulsion and spacecraft center of mass (c.m.) control. A leak-free cycle life capability of nine reversals was demonstrated. The diaphragms rolled smoothly from ring to ring in a predictable manner on the first reversal. Varying amounts of diaphragm cocking and ring skipping were observed on subsequent reversals. The diaphragm pressure differential did not exceed 10 psid during any reversal. Cycle life capability, reversal mode, and pressure differential were not affected by sudden reversals, environmental tests, or 18,000 partial reversals. An expulsion efficiency of approximately 97 percent was demonstrated. The results of these tests show that metallic diaphragms can be used as an effective means of positive fuel expulsion; however, to achieve spacecraft c.m. control, the diaphragm must not be reversed prior to flight.

Woodruff, W. L.↗
NASA NTRS1973

Electromagnetic position sensor for a magnetically supported model in a wind tunnel

An investigation was undertaken to determine the feasibility of using superconducting force-producing coils for positioning a model in a wind tunnel. The cryostat containing the forcing coils surrounded the test section of the tunnel, thus favoring an electromagnetic position sensor. Another reason favoring this choice was the fact that the performance of an electromagnetic sensor is essentially unaffected by the shape of the model.

Towler, W. R.↗
NASA NTRS1973

Temporal variations in the dawn and dusk midlatitude trough position-modeled and measured (Ariel 3)

The temporal development of the latitudinal position of the 600 km midlatitude electron density trough at dawn and dusk during the period 25-27 May 1967, which encompassed a large magnetic storm, was measured by the RF capacitive probe on the polar orbiting Ariel 3 satellite. The substorm-related changes in the L coordinate of the trough minimum and the point of most rapid change of density gradient on the low latitude side of the trough are similar. Oscillations of the trough position at dusk are in phase with substorm activity whereas movement of the trough at dawn is only apparent with the onset of the large storm. Near dusk there is evidence of structure in the form of a tail-like extension of the plasmasphere at the peak of the storm. Detailed model calculations assuming a spatially invariant equatorial convection E field which varies in step with K sub p index reproduces much of the observed behavior, particularly at dusk, and shows that more than one plasmapause-type transition may be identifiable in the trough region.

Grebowsky, J. M.↗
NASA NTRS1973

Si(Li) position sensitive detector

A position sensitive detector was made using the lithium diffused layer of a lithium-drifted-silicon detector as the uniform resistive layer. An expression is derived for estimating the resistance from the thickness of the lithium layer. Expressions for the noise and ballistic deficit for single differentiation-double integration pulse shaping are presented. Room temperature data for a 1 Mev proton beam on a 45 mm long detector shows that the linearity is better than .05% and that the position resolution is 1.06 + or - .05 mm.

Gigante, J. R.↗
NASA NTRS1972

Pole position studied with artificial earth satellites.

Long-arc orbit computation of highest accuracy can provide pole positions. Optical Baker-Nunn and laser range observations of several satellites are combined. The accuracy of the pole position is comparable to that of the mean satellite-tracking station coordinates (plus or minus 5 m) when sufficient tracking data are available. Exploitation of the technique requires more accurate tracking data.

Gaposchkin, E. M.↗
NASA NTRS1973

X-ray pulse profile and celestial position of Hercules X-1.

The celestial position of the binary X-ray source Her X-1 has been measured with a precision of 30 sec and, within the uncertainties, agrees with the position of the optical variable HZ Herculis. An average light curve for the 1.24-sec periodicity has been obtained with about 10-msec resolution. The average pulse is a double-peaked structure which shows significant intensity changes in time scales down to 30 msec.

Doxsey, R.↗
NASA NTRS1973

Corrections of satellite positions in near-real time.

The influence of sudden increases of electron content on the accurate determination of the position of a satellite is investigated based on a spherically stratified ionospheric model. Using the total electron content information from Faraday rotation measurements, a procedure is presented whereby the corrections of satellite position due to the unpredicted electron increase can be accounted for without the need to know the spatial distribution of the additional electrons.

Poularikas, A. D.↗
NASA NTRS1973

Excitation of the CO fourth positive system by the dissociative recombination of CO2/+/ ions.

The fourth positive system of CO has been excited in a static afterglow experiment by the dissociative recombination of CO2(+) ions. From combined absolute optical and microwave measurements the specific recombination coefficient for exciting the CO system was found to be (2 plus 1 or minus 0.5) x 10 to the minus 8th cu cm/sec. This value represents approximately 5% of the total recombination coefficient (4.0 plus or minus 0.5) x 10 to the minus 7th cu cm/sec measured in this experiment, implying that CO2(+) dissociative recombination will contribute significantly to the excitation of the CO fourth positive system in the Martian airglow. Corroborative electron heating experiments showed that the magnitude of the specific recombination coefficient decreased as the electron temperature was increased. Evidence was also found for the presence of vibrationally excited ions in the CO2(+) plasma, a result which indicates that analogous laboratory studies on the dissociative recombination of O2(+), N2(+), and NO(+) ions may have also involved vibrationally hot plasmas.

Gutcheck, R. A.↗
NASA NTRS1973

En route position and time control of aircraft using Kalman filtering of radio aid data

Fixed-time-of-arrival (FTA) guidance and navigation is investigated as a possible technique capable of operation within much more stringent en route separation standards and offering significant advantages in safety, higher traffic densities, and improved scheduling reliability, both en route and in the terminal areas. This study investigated the application of FTA guidance previously used in spacecraft guidance. These FTA guidance techniques have been modified and are employed to compute the velocity corrections necessary to return an aircraft to a specified great-circle reference path in order to exercise en route time and position control throughout the entire flight. The necessary position and velocity estimates to accomplish this task are provided by Kalman filtering of data from Loran-C, VORTAC/TACAN, Doppler radar, radio or barometric altitude,and altitude rate. The guidance and navigation system was evaluated using a digital simulation of the cruise phase of supersonic and subsonic flights between San Francisco and New York City, and between New York City and London.

Mcgee, L. A.↗
NASA NTRS1973

An experimental evaluation of metallic diaphragms for positive fuel expulsion in the atmosphere explorer hydrazine propulsion subsystem

Four Arde conospheroid metallic diaphragms were tested to evaluate their capability for use in the orbit adjust propulsion subsystem (OAPS) of the Explorer spacecraft. The diaphragms will be used for positive propellant expulsion and spacecraft center of mass control. A leak-free cycle life capability of nine reversals was demonstrated. The diaphragms rolled smoothly from ring to ring in a predictable manner on the first reversal. Varying amounts of diaphragm cocking and ring skipping were observed on subsequent reversals. The diaphragm pressure differential did not exceed 7 N/sq cm during any reversal. Cycle life capability, reversal mode, and pressure differential were not affected by sudden reversals, environmental tests, or 18,000 partial reversals. An expulsion efficiency of approximately 97 percent was demonstrated. The results of these tests show that metallic diaphragms can be used as an effective means of positive fuel expulsion; however, to achieve spacecraft center of mass control, the diaphragm must not be reversed prior to flight.

Woodruff, W. L.↗
NASA NTRS1973

A high resolution study in time, position, intensity, and frequency of a radio event on 14 January 1971

High resolution position and spectrum measurements were made of a complex solar radio activity on January 14, 1971, from 1120 to 1130 UT. Positions were measured with 169 MHz Nancay E-W Radioheliograph, while dynamic spectra and polarization were observed with the 60-channel radiospectrograph of Nera. The radio event consisted of two closely similar groups of type 3 bursts and type 2-like details, and a stationary type 4 continuum, including some very clear pulsating structures. The general aspect of this activity is presented.

Caroubalos, C.↗
NASA NTRS1974

Two-position dc pulse voltage stabilizer

The advantages of the dc pulse voltage stabilizers over the continuous action stabilizers are described. These advantages include higher efficiency, low sensitivity to the ambient temperature and insignificant size and weight. A comparison is made between the schematics of the known two position pulse stabilizer with a Schmitt trigger and that developed by the author. A characteristic feature of the improved system is the increased stabilization coefficient and the possibility of smooth regulation of the output voltage. A practical schematic is presented for the improved two position pulse stabilizer along with its parameters.

Osadchiy, V. I.↗
NASA NTRS1974

Effects of an anti-G suit on the hemodynamic and renal responses to positive /+Gz/ acceleration

The effects of the currently used U.S. Air Force (CSU-12/P) anti-G suit on renal function during positive radial acceleration (+Gz) were assessed in seven normal male subjects in balance on a 200 meq sodium diet. Following suit inflation in the seated position, +2.0 Gz for 30 min resulted in a decrease in the rate of sodium excretion from 125 plus or minus 19 to 60 plus or minus 14 microeq/min, which persisted during a 25-min recovery period. Fractional excretion of sodium also decreased significantly during +Gz. The magnitude of the antinatriuresis was indistinguishable from that observed during +Gz without suit inflation. In contrast to the antinatriuresis observed during centrifugation without suit, however, the antinatriuresis with suit was mediated primarily by an enhanced tubular reabsorption of sodium.

Shubrooks, S. J., Jr.↗
NASA NTRS1974

Temporal variations in the dawn and dusk midlatitude trough and plasmapause position

The temporal development of the latitudinal position of a 600-km midlatitude electron density trough at dawn and dusk during the period 25-27 May 1967, which encompassed a large magnetic storm, was measured by the RF capacitive probe on the polar orbiting Ariel 3 satellite. The substorm-related changes in the L coordinate of the trough minimum and the point of most rapid change of density gradient on the low latitude side of the trough are similar. Oscillations of the trough position at dusk are in phase with substorm activity whereas movement of the trough at dawn is only apparent with the onset of the large storm. Detailed model calculations of the plasmasphere dynamics assuming a spatially invariant equatorial convection E-field which varies in step with the K sub p index produces a plasmapause motion which parallels the observed trough behaviour.

Grebowsky, J. M.↗