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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 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
NASA NTRS1973

Analysis of ground tests of a microwave, earth-occultation, pressure-reference-level system.

A two-satellite, microwave, earth-occultation system can supplement an infrared sensor by providing an accurate altitude reference that will serve to fix, as a function of height, the derived temperature profile of the infrared sounder. The results of ground tests made in Hawaii to estimate the likely effects of scintillation and fading on an occultation system are described. It was found that the microwave signal suffered periods of intense fading; extensive computer analyses of the data were performed in which aircraft-generated refractivity profiles were subjected to ray tracing. Results of these analyses indicate that the probable cause of the observed fading was multipath, a low-altitude phenomenon usually attributed to water vapor inhomogeneities. It is maintained that multipath will therefore have minimal effect on the pressure-reference microwave occultation system, which would operate at a relatively high closest-approach altitude (about 8 km).

Ungar, S. G.↗
NASA NTRS1973

A buoyant tornado-probe concept incorporating an inverted lifting device

Addition of an inverted lifting device to a simple balloon probe is shown to make possible low-altitude entry to tornado cores with easier launch conditions than for the simple balloon probe. Balloon-lifter combinations are particularly suitable for penetration of tornadoes with average to strong circulation, but tornadoes of less than average circulation which are inaccessible to simple balloon probes become accessible. The increased launch radius which is needed for access to tornadoes over a wide range of circulation results in entry times of about 3 minutes. For a simple balloon probe the uninflated balloon must be first dropped on, or near, the track of the tornado from a safe distance. The increase in typical launch radius from about 0.75 kilometer to slightly over 1.0 kilometer with a balloon-lifter combination suggests that a direct air launch may be feasible.

Grant, F. C.↗
NASA NTRS1973

S-band transponder experiment

The purpose of this experiment was to measure the variations in the lunar gravitational field near the trajectory of orbiting space vehicles (the command and service module (CSM) and the small particles and fields subsatellites ejected from the Apollo 15 and 16 spacecraft). New information has been obtained from all Apollo orbiting spacecraft; however, this report shall be limited to the results from the Apollo 17 CSM and the Apollo 16 subsatellite. The data acquired are precise speed measurements of the orbiting spacecraft from which accelerations or gravity profiles may be inferred. Feature resolution is controlled by the spacecraft altitude and is almost a direct relationship (i.e., data taken from a 50-km altitude will resolve approximately a 50-km feature). Therefore, revolutions 3 to 12, when the CSM was in the low-altitude orbits, provided the clearest information.

Sjogren, W. L.↗
NASA NTRS1974

Effluent sampling of Scout D and Delta launch vehicle exhausts

Characterization of engine-exhaust effluents (hydrogen chloride, aluminum oxide, carbon dioxide, and carbon monoxide) has been attempted by conducting field experiments monitoring the exhaust cloud from a Scout-Algol III vehicle launch and a Delta-Thor vehicle launch. The exhaust cloud particulate size number distribution (total number of particles as a function of particle diameter), mass loading, morphology, and elemental composition have been determined within limitations. The gaseous species in the exhaust cloud have been identified. In addition to the ground-based measurements, instrumented aircraft flights through the low-altitude, stabilized-exhaust cloud provided measurements which identified CO and HCI gases and Al2O3 particles. Measurements of the initial exhaust cloud during formation and downwind at several distances have established sampling techniques which will be used for experimental verification of model predictions of effluent dispersion and fallout from exhaust clouds.

Hulten, W. C.↗
NASA NTRS1974

Analysis of sonic boom measurements near shock wave extremities for flight near Mach 1.0 and for airplane accelerations

The analysis of the 14 low-altitude transonic flights showed that the prevailing meteorological consideration of the acoustic disturbances below the cutoff altitude during threshold Mach number flight has shown that a theoretical safe altitude appears to be valid over a wide range of meteorological conditions and provides a reasonable estimate of the airplane ground speed reduction to avoid sonic boom noise during threshold Mach number flight. Recent theoretical results for the acoustic pressure waves below the threshold Mach number caustic showed excellent agreement with observations near the caustic, but the predicted overpressure levels were significantly lower than those observed far from the caustic. The analysis of caustics produced by inadvertent low-magnitude accelerations during flight at Mach numbers slightly greater than the threshold Mach number showed that folds and associated caustics were produced by slight changes in the airplane ground speed. These caustic intensities ranged from 1 to 3 time the nominal steady, level flight intensity.

Haglund, G. T.↗
NASA NTRS1974

Plasma waves in the dayside polar cusp. II - Magnetopause and polar magnetosheath

During the outbound pass of Nov. 1, 1968, Ogo 5 sporadically encountered the low-altitude polar cusp at low magnetic latitudes. The spacecraft remained in the cusp beyond six earth radii, and it then traversed the interface region between the magnetospheric cusp and the magnetosheath. Two large scale discontinuities were detected in this sheath-cusp transition region, and several possible interpretations are evaluated here. At 1427 UT, local changes in magnetic field orientation and the variation in ULF magnetic power spectral density were typical of shifts detected at the magnetopause, although the spacecraft did not traverse a true boundary of warm plasma at this point. The second discontinuity, detected at 1456 UT, resembled a collisionless shock, and it was characterized by observations of intense, impulsive VLF electric field bursts and rapid local variations in both total ion flux and differential electron flux. The simplest interpretation is that Ogo 5 had traversed a standing shock within the sheath.

Scarf, F. L.↗
NASA NTRS1975

Electron precipitation in the post midnight sector of the auroral zones

Comprehensive measurements of the angular distributions and energy spectra of electron intensities with electrostatic analyzer arrays on board the low-altitude satellite Injun 5 are reported. These are for the post-midnight sector of the auroral zones during the high-intensity events accompanying magnetic substorms. Precipitation features on closed terrestrial field lines well equatorward of the trapping boundary for energetic electrons with E greater than 45 keV were examined. No evidences of maxima in the differential energy spectra or of strongly field-aligned currents which are indicative of quasi-static electric fields aligned parallel to the geomagnetic field were found. Precipitation of low-energy electron intensities fluctuated on time scales greater than 2 seconds as viewed at the satellite position. This precipitation was characterized by isotropy for all pitch angles outside the atmospheric backscatter cone.

Frank, L. A.↗
NASA NTRS1975

Simultaneous particle and field observations of field-aligned currents

Simultaneous measurements of low-energy precipitating electrons and magnetic fluctuations from the low-altitude polar-orbiting satellite Ogo 4 have been compared. Analysis of the two sets of experimental data for isolated events led to the classification of high-latitude field-aligned currents as purely temporal or purely spatial variations. Magnetic field disturbances calculated by using these simple current models and the measured particle fluxes were in good agreement with measured field values. Although fluxes of electrons of greater than 1 keV were detected primarily on the night side, magnetometer disturbances indicative of field-aligned currents were seen at all local times, in both the visual auroral regions and the day side polar cusp. Thus electrons with energies of less than about 1 keV are the prime charge carriers in high-latitude day side field-aligned currents.

Berko, F. W.↗
NASA NTRS1975

On the source of lunar limb compressions

Magnetic-field measurements made on board the Apollo 15 and 16 subsatellites in low-altitude lunar orbit are used to study compressions of the magnetic field over terminator regions when the moon is in the solar wind. These compressional disturbances occur at just in front of the terminator, but only when specific selenographic regions appear at the lunar limb. The occurrence rate, strength, and position of the compression relative to the limb are different for each source region. Where overlaps of limb-compression occurrence statistics and lunar magnetic-field maps exist, the limb-compression occurrence rates have a high degree of correlation with magnetic-field strength. Thus the most probable cause of limb compressions is deflection of the solar wind by the lunar surface magnetic field as the solar wind flows past the lunar terminators.

Russell, C. T.↗
NASA NTRS1975

System measurements of a CO2 laser communications link

Measurements were made under simulated operating conditions to establish the capability of a CO2 laser transmitting heterodyne receiver link to acquire weak laser transmitter beams and maintain spatial tracking during communications. For the case of a synchronous satellite-to-earth station link, analysis and laboratory measurements indicate that the infrared heterodyne receiver subsystem is capable of performing the acquisition, acquisition confirm, and spatial tracking functions at IF signal-to-noise ratio of -17 dB. For the case of a low-altitude satellite-to-earth station link, the laser transmit signal is Doppler-shifted due to the difference in relative velocity of the two stations. The resultant Doppler frequency shift varies with time and must be spectrally acquired and tracked.

Peyton, B. J.↗
NASA NTRS1963

Launch Vehicle Flight Report - Nasa Project Apollo Little Joe 2 Qualification Test Vehicle 12-50-1

The Little Joe II Qualification Test Vehicle, Model 12-50-1, was launched from Army Launch Area 3 {ALA-3) at White Sands Missile Range, New Mexico, on 28 August 1963. This was the first launch of this class of boosters. The Little Joe II Launch Vehicle was designed as a test vehicle for boosting payloads into flight. For the Apollo Program, its mission is to serve as a launch vehicle for flight testing of the Apollo spacecraft. Accomplishment of this mission requires that the vehicle be capable of boosting the Apollo payload to parameters ranging from high dynamic pressures at low altitude to very high altitude flight. The fixed-fin 12-50 version was designed to accomplish the low-altitude parameter. The 12-51 version incorporates an attitude control system to accomplish the high altitude mission. This launch was designed to demonstrate the Little Joe II capability of meeting the high dynamic pressure parameter for the Apollo Program. For this test, a boiler-plate version of the Apollo capsule, service module and escape tower were attached to the launch vehicle to simulate weight, center of gravity and aerodynamic shape of the Apollo configuration. No attempt was made to separate the payload in flight. The test was conducted in compliance with Project Apollo Flight Mission Directive for QTV-1, NASA-MSC, dated 3 June 1963, under authority of NASA Contract NAS 9-492,

Source record↗
NASA NTRS1955

Performance of Four Experimental High-btu-per-gallon Fuels in a Single Turbojet Combustor

Performance characteristics of four hydrocarbon fuels having high Btu per gallon were determined in a single turbojet combustor. At simulated low-altitude operating conditions, the fuels with high Btu per gallon generally produced more carbon than did JP-4 and JP-5 fuels. The deposits were reduced appreciably with a fuel-oil additive. At high-altitude conditions, the high Btu-per-gallon fuels gave lower efficiencies than did JP-4 or JP-5 fuels. No attempts were made to improve performance by combustor design modification.

Jonash, Edmund R↗
NASA NTRS1928

Preliminary Flight Tests of the N.A.C.A. Roots Type Aircraft Engine Supercharger

An investigation of the suitability of the N.A.C.A. Roots type aircraft engine supercharger to flight-operating conditions, as determined the effects of the use of the supercharger upon engine operation and airplane performance, is described in this report. Attention was concentrated on the operation of the engine-supercharger unit and on the improvement of climbing ability; some information concerning high speeds at altitude was obtained. The supercharger was found to be satisfactory under flight-operating conditions. Although two failures occurred during the tests, the causes of both were minor and have been eliminated. Careful examination of the engines revealed no detrimental effects which could be attributed to supercharging. Marked improvements in climbing ability and high speeds at altitude were effected. It was also found that the load which could be carried to a given moderate or high altitude in a fixed time was considerably augmented. A slight sacrifice of low-altitude performance was necessitated, however, by the use of a fixed-pitch propeller. From a consideration of the very satisfactory flight performance of the Roots supercharger and of its inherent advantages, it is concluded that this type is particularly attractive for use in certain classes of commercial airplanes and in a number of military types.

Gardiner, Arthur W↗
NASA NTRS1957

Satellite and space propulsion system

Previous papers of this conference have described rocket systems capable of launching sizable payloads into satellite orbits. Propulsion systems that might be suitable for the next steps are discussed in this paper. Some of the uses for propulsion systems once satellites have been established are as follows: (1) increasing lifetime of low-altitude satellite, (2) controlling and altering satellite orbits, (3) lunar and interplanetary exploration and (4) auxiliary electric power. (author)

Moeckel, W E↗
NASA NTRS1955

Investigation in the Langley Free-Flight Tunnel of the Low-Speed Stability and Control Characteristics of a 1/10-Scale Model Simulating the Convair F-102A Airplane

An investigation of the low-speed, power-off stability and control characteristics of a 1/10-scale model simulating the Convair F-102A airplane has been made in the Langley free-flight tunnel. The model in its basic configuration and with two modifications involving leading- edge slats and an increase in vertical-tail size was flown through a lift-coefficient range from 0.7 to the stall. Only relatively low-altitude conditions were simulated. The longitudinal stability characteristics of the model were considered satisfactory for all conditions investigated. The lateral stability characteristics were considered satisfactory for the basic configuration over the lift-coefficient range investigated, except near the stall, where large values of static directional instability caused the model to be directionally divergent. An 80-percent increase in vertical-tail area increased the angle of attack at which the model became directionally divergent. The longitudinal and lateral control characteristics were generally satisfactory. Although the adverse sideslip characteristics for the model were considered acceptable over the angle-of-attack range, analysis indicates that the adverse sideslip characteristics of the airplane may be objectionable at high angles of attack.

Boisseau, Peter C.↗
NASA NTRS1953

Investigation of the Low-Speed Stability and Control Characteristics of a 1/10-Scale Model of the Convair YF-102 Airplane in the Langley Free-Flight Tunnel

An investigation of the low-speed, power-off stability and control characteristics of a 1/10-scale model of the Convair YF-102 airplane has been made in the Langley free-flight tunnel. The model was flown over a lift-coefficient range from 0.5 to the stall in its basic configuration and with several modifications involving leading-edge slats and increases in vertical-tail size. Only relatively low-altitude conditions were simulated and no attempt was made to determine the effect of freeing the controls. The longitudinal stability characteristics of the model were considered satisfactory for all conditions investigated. The lateral stability characteristics were considered satisfactory for the basic configuration over the speed range investigated except near the stall, where large values of static directional instability caused the model to be directionally divergent. The addition of leading-edge slats or an 8-percent increase in vertical-tail area increased the angle of attack at which the model became directionally divergent. The use of leading-edge slats in combination with a 40-percent increase in vertical-tail size eliminated the directional divergence and produced satisfactory stability characteristics through the stall. The longitudinal and lateral control characteristics were generally satisfactory. Although the adverse sideslip characteristics for the model were considered satisfactory over the angle-of-attack range, analysis indicates that the adverse sideslip characteristics of the airplane may be objectionable at high angles of attack.

Johnson, Joseph L., Jr.↗
NASA NTRS1951

Investigation of the Low-Speed Stability and Control Characteristics of a 1/10-Scale Model of the Douglas XF4D-1 Airplane in the Langley Free-Flight Tunnel TED No. NACA DE 349

An investigation of the low-speed, power-off stability and control characteristics of a 1/10-scale model of the Douglas XF4D-1 airplane has been made in the Langley free-flight tunnel. The model was flown with leading-edge slats retracted and extended over a lift-coefficient range from 0.5 to the stall. Only relatively low-altitude conditions were simulated and no attempt was made to determine the effect on the stability characteristics of freeing the controls. The longitudinal stability and control characteristics of the model were satisfactory for all conditions investigated except near the stall with slats extended, where the model had a slight nosing-up tendency. The lateral stability and control characteristics of the model were considered satisfactory for all conditions investigated except near the stall with slats retracted, where a change in sign of the static- directional-stability parameter Cn(sub beta) caused the model to be directionally divergent. The addition of an extension to the top of the vertical tail did not increase Cn(sub beta) enough to eliminate the directional divergence of the model, but a large increase in Cn(sub beta) that was obtainable by artificial means appeared to eliminate the divergence and flights near the stall could be made. Artificially increasing the stability derivative-Cn(sub r) (yawing moment due to yawing) and Cn(sub p) (yawing moment due to rolling) had little effect on the divergence for the range of these parameters investigated. Calculations indicate that the damping of the lateral oscillation of the airplane with slats retracted or extended will be satisfactory at sea level but will be only marginally satisfactory at 40,000 feet.

Johnson, Joseph L.↗
NASA NTRS1951

Strain-Gage Measurements of Buffeting Loads on a Jet-Powered Bomber Airplane

Buffet boundaries, buffeting-load increments for the stabilizers and elevators, and buffeting bending-moment increments for the stabilizers and wings as measured in gradual maneuvers for a jet-powered bomber airplane are presented. The buffeting-load increments were determined from strain-gage measurements at the roots or hinge supports of the various surfaces considered. The Mach numbers of the tests ranged from 0.19 to 0.78 at altitudes close to 30,000 feet. The predominant buffet frequencies were close to the natural frequencies of the structural components. The buffeting-load data, when extrapolated to low-altitude conditions, indicated loads on the elevators and stabilizers near the design limit loads. When the airplane was held in buffeting, the load increments were larger than when recovery was made immediately.

Aiken, William S., Jr.↗