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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 667 records · Page 37
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NASA NTRS1979

Effect of number of probes and their orientation on the calculation of several compressor face distortion descriptors

A study was performed to determine the effects of the number and position of total pressure probes on the calculation of five compressor face distortion descriptors. This study used three sets of 320 steady state total pressure measurements that were obtained with a special rotating rake apparatus in wind tunnel tests of a mixed-compression inlet. The inlet was a one third scale model of the inlet on a YF-12 airplane, and it was tested in the wind tunnel at representative flight conditions at Mach numbers above 2.0. The study shows that large errors resulted in the calculation of the distortion descriptors even with a number of probes that were considered adequate in the past. There were errors as large as 30 and -50 percent in several distortion descriptors for a configuration consisting of eight rakes with five equal-area-weighted probes on each rake.

Stoll, F.↗
NASA NTRS1979

Study of entry and landing probes for exploration of Titan

Saturn's largest moon, Titan, is a totally unique planetary body which is certain to yield exciting new phenomena. Current information is lacking in detail to distinguish between a thin methane rich atmosphere and a thick nitrogen rich atmosphere. Therefore, both the thin and thick atmospheric models were used for the study of various Titan probe classes described in this report. The technical requirements, conceptual design, science return, schedule, cost and mission implications of three probe classes that could be used for exploration of Titan are defined. The three probe classes were based on a wide range of exploration mission possibilities.

Source record↗
NASA NTRS1978

Sealing scientific probes against deep space and the Venusian environment A tough job

The Pioneer Venus mission evolved from studies conducted during the late 1960s and early 1970s. It was found that a need existed for low cost orbiters and landers to explore the planet. The considered mission was to be accomplished with six separate vehicles arriving at Venus nearly simultaneously in mid-December 1978. The probes are designed to survive entry and descent into the atmosphere. A description is presented of the approaches used to maintain sealing integrity for the large and small probes under the constraints imposed by the harsh Venusian environment. Attention is given to probe vehicle configuration, pressure vessel sealing requirements, material and configuration considerations, permanent seals, separable seals, development problems, and aspects of seal testing.

Pokras, J.↗
NASA NTRS1979

Structure of the atmosphere of Venus up to 110 kilometers - Preliminary results from the four Pioneer Venus entry probes

Each of the four Pioneer Venus probes carried instruments to measure the structure of the atmosphere, both below the cloud deck and above it to an altitude of at least 120 km. Preliminary results are presented on lower-atmosphere structure, thermal contrasts, and atmospheric stability. Altitudes derived from the data are given along with the temperature profile from 67 to 105 km, derived from the first analysis of the entry data from the north probe. All four probes lost temperature data at the 640 K level, which is at an altitude of about 12 to 14 km. Values of temperature and pressure at touchdown are presented in a table. The pressure differences imply terrain elevation differences at the landing sites. Above 40 km, the measured profile moves from near-adiabatic toward the theoretical profile for radiative equilibrium.

Seiff, A.↗
NASA NTRS1978

Electron paramagnetic resonance studies of slowly tumbling vanadyl spin probes in nematic liquid crystals

The purposes of this vanadyl spin probe study are threefold: (1) to establish when the breakdown of motionally narrowed formulas occurs; (2) to analyze the experimental vanadyl EPR line shapes by the stochastic Lioville method as developed by Polnaszek et al. (1973) for slow tumbling in an anisotropic liquid; and (3) to compare the vanadyl probe study results with those of Polnaszek and Freed (1975). Spectral EPR line shapes are simulated for experimental spectra of vanadyl acetylacetonate (VOAA) in nematic liquid crystal butyl p-(p-ethoxyphenoxycarbonyl) phenyl carbonate (BEPC) and Phase V of EM laboratories. It is shown that the use of typical vanadyl complexes as spin probes for nematic liquid crystals simplifies the theoretical analysis and the subsequent interpretation. Guidelines for the breakdown of motionally narrowed formulas are established. Both the slow tumbling aspects and the effects of non-Brownian rotation should be resolved in order to extract quantitative information about molecular ordering and rotational mobility.

Bruno, G. V.↗
NASA NTRS1979

The Saturn Orbiter Dual Probe mission concept

This paper presents the results of a mission design study for NASA of the next Saturn mission to follow Voyager. The Saturn Orbiter Dual Probe (SO2P) mission combines three spacecraft - a Saturn orbiter, a Saturn probe, and a Titan probe/lander - into a multipurpose Saturn exploration package. The mission is to conduct a survey from orbit around Saturn and to physically probe bodies in the Saturnian system, the first such mission to do so. The mission has many possible options including: combining solar electric propulsion with earth gravity assist, assembling of IUS stages in orbit, and aerocapture at Titan to insert into Saturn orbit.

Roberts, P. H., Jr.↗
NASA NTRS1979

Displacement probes with self-contained exciting medium

A transducer that combines a noncontacting displacement probe with a self-contained target is described. The target is held in position against a vibrating surface by a housing which also supports the noncontacting probe. The target vibrates with the surface and the probe senses the vibrations of the target.

Miserentino, R.↗
NASA NTRS1980

Wake flowfields for Jovian probe

The wake flow field developed by the Galileo probe as it enters the Jovian atmosphere was modeled. The wake produced by the probe is highly energetic, yielding both convective and radiative heat inputs to the base of the probe. A component mathematical model for the inviscid near and far wake, the viscous near and far wake, and near wake recirculation zone was developed. Equilibrium thermodynamics were used for both the ablation and atmospheric species. Flow fields for three entry conditions were calculated. The near viscous wave was found to exhibit a variable axial pressure distribution with the neck pressure approximately three times the base pressure. Peak wake flow field temperatures were found to be in proportion to forebody post shock temperatures.

Engel, C. D.↗
NASA NTRS1980

Titan probe technology assessment and technology development plan study

The need for technology advances to accomplish the Titan probe mission was determined by defining mission conditions and requirements and evaluating the technology impact on the baseline probe configuration. Mission characteristics found to be technology drivers include (1) ten years dormant life in space vacuum; (2) unknown surface conditions, various sample materials, and a surface temperature; and (3) mission constraints of the Saturn Orbiter Dual Probe mission regarding weight allocation. The following areas were identified for further development: surface sample acquisition system; battery powered system; nonmetallic materials; magnetic bubble memory devices, and the landing system. Preentry science, reliability, and weight reduction and redundancy must also be considered.

Castro, A. J.↗
NASA NTRS1980

Surface reflections of Pioneer Venus probe signals

As the four Pioneer Venus probes fell within the atmosphere toward the surface of Venus, each of them transmitted a radio signal directly to earth. Because of the relatively broad antenna beamwidth of these small probes, some of the transmitted power went down to the surface of Venus. This paper reports the discovery that the radio signals scattered off the surface are not only detectable but that their characteristics can be determined with a surprising degree of certainty. From these characteristics one can determine parameters of the Venusian atmospheric winds and of the surface that promise to be useful. Most of the scattered energy is that which originally radiated from the probes in a near-horizontal direction; the downward-directed radiation is detectable but much weaker. Refraction in the atmosphere of Venus clearly plays a significant role in establishing both the strength of scatter and its Doppler shift.

Croft, T. A.↗
NASA NTRS1980

Comparisons of subsonic drag estimates derived from Pioneer Venus probes flight data with wind-tunnel results

Subsonic drag coefficients have been obtained from flight data for the Pioneer Venus multiprobes. The technique used to extract the information from the data consisted of utilizing in situ pressure and temperature measurements. Analysis of the major model parameter error sources indicates overall error levels of five percent or less in the flight values of the drag coefficient. Comparisons of the flight coefficients with preflight wind-tunnel test data showed generally good agreement except for the Sounder descent probe configuration. To preclude atmospheric phenomena as a possible explanation of this difference, additional wind-tunnel tests were performed on the Sounder descent probe. Special attempts were made to duplicate the probe geometry for tests in a high Reynolds number environment in order to achieve as realistic model and flight conditions as practical. Preliminary results from this testing in the NASA LaRC Low Turbulence Pressure Tunnel produced a drag coefficient of 0.68 at 0 deg angle of attack which is within the expected accuracy limits of the flight derived drag coefficient value of 0.72 + or - 0.04, thus eliminating atmospheric phenomena as the explanation for the initial difference.

Blanchard, R. C.↗
NASA NTRS1982

Multipressure and Temperature Probe

Aerodynamic probe is a small cylinder tube holding a network of tiny tubes leading to various ports. Six parameters are recorded simultaneously with little interference with aerodynamic flow. Two tubes connected by a hot-wire tungsten probe sense steady and fluctuating components of total and static pressures; the feedbacks from these tubes are input into differential-pressure sensors to measure fluctuating components of the pressures. Data are recorded by instruments at the back end of the probe.

Raman, K. R.↗
NASA NTRS1981

Galileo probe forebody thermal protection - Benchmark heating environment calculations

Solutions are presented for the aerothermal heating environment for the forebody heatshield of candidate Galileo probe. Entry into both the nominal and cool-heavy model atmospheres were considered. Solutions were obtained for the candidate heavy probe with a weight of 310 kg and a lighter probe with a weight of 290 kg. In the flowfield analysis, a finite difference procedure was employed to obtain benchmark predictions of pressure, radiative and convective heating rates, and the steady-state wall blowing rates. Calculated heating rates for entry into the cool-heavy model atmosphere were about 60 percent higher than those predicted for the entry into the nominal atmosphere. The total mass lost for entry into the cool-heavy model atmosphere was about 146 kg and the mass lost for entry into the nominal model atmosphere was about 101 kg.

Balakrishnan, A.↗
NASA NTRS1981

Survey of the supporting research and technology for the thermal protection of the Galileo Probe

The Galileo Probe, which is scheduled to be launched in 1985 and to enter the hydrogen-helium atmosphere of Jupiter up to 1,475 days later, presents thermal protection problems that are far more difficult than those experienced in previous planetary entry missions. The high entry speed of the Probe will cause forebody heating rates orders of magnitude greater than those encountered in the Apollo and Pioneer Venus missions, severe afterbody heating from base-flow radiation, and thermochemical ablation rates for carbon phenolic that rival the free-stream mass flux. This paper presents a comprehensive survey of the experimental work and computational research that provide technological support for the Probe's heat-shield design effort. The survey includes atmospheric modeling; both approximate and first-principle computations of flow fields and heat-shield material response; base heating; turbulence modelling; new computational techniques; experimental heating and materials studies; code validation efforts; and a set of 'consensus' first-principle flow-field solutions through the entry maneuver, with predictions of the corresponding thermal protection requirements.

Howe, J. T.↗
NASA NTRS1982

A study of the vent pipe for the gravity probe-B

The Gravity Probe B experiment to test Einstein's relativity theory is a possible Space Shuttle project. Cooling of the gyroscopes and thrusting of the Probe into a zero-drag environment is accomplished by vaporizing liquid helium and venting the gas from the Probe through a nozzle system. In order to avoid malfunctioning of this cooling-thruster system, the pressure difference across the vent pipe-thruster system must be maintained to be less than the vapor pressure of liquid helium at the given temperature. This study investigated helium gas flow through the vent pipe for various configurations, mass flow rates, and pipe diameters. In addition, pertinent properties of both liquid and gaseous helium were investigated. It was observed that helical coiling of the pipe about the Dewar caused less frictional drag and less pressure change than did sharp pipe bending. Also, for various flow rates and nozzle throat area sizes, the system would malfunction for a given bath temperature.

Knoshaug, R. N.↗
NASA NTRS1982

Transit Thermal Control Design for Galileo Entry Probe for Planet Jupiter

A totally passive design was completed for the thermal control of the Galileo entry probe during its transit to the planet Jupiter. The design utilizes radio isotope heater units, multilayer insulation blankets and a thermal radiator in conjunction with a design conductance support structure to achieve both the required storage and critical initial planet atmosphere entry temperatures. The probe transit thermal design was completed and verified based on thermal vacuum testing of a prototype probe thermal test model.

Haverly, George C.↗
NASA NTRS1981

Parachute design for Galileo Jupiter entry probe

This paper discusses the parachute subsystem used on an atmospheric entry probe that will descend through the clouds of Jupiter. The entry probe is a part of the Galileo Project to be launched in 1985 aboard the Space Shuttle; the entry probe will encounter the planet in 1988. The parachute subsystem consists of a pilot parachute and a main parachute, and both are of conventional conical ribbon design. Key considerations in the design of the parachutes and a summary of the parachute subsystem test program, which includes two air drop tests and a systems drop test (balloon launched), are presented.

Rodier, R. W.↗
NASA NTRS1982

A hot-film static-pressure probe

The procedure described involves calibrating the probe in the gas of interest over the range of temperatures and pressures anticipated in the wind-tunnel tests and then applying the calibration to reduce the data from those tests. Pressure readings from two probes, one having two hot-film sensors and an internal sonic orifice and the other connected to a conventional pressure gage, are recorded for several Reynolds numbers and compared. The conventional static-pressure probe with a pair of hot-film sensors and an interior sonic orifice is shown to provide the means of surveying flowfields in hypersonic flow at a rapid rate and with an accuracy of better than + or - 10%.

Ashby, G. C., Jr.↗