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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 271 records · Page 15
All sourcesNASA NTRSDOE OSTI
NASA NTRS1983

Thermal-protection requirements for near-earth aero-assisted orbital-transfer vehicle missions

The thermal protection required for decelerating and maneuvering spacecraft by aerodynamic forces is determined for return missions from geosynchronous to low-earth orbits. The effect of vehicle configuration on surface heating rates and selection of heat-shield materials is analyzed. Effects of the current widespread estimates in the structure of atmospheric density are also evaluated. It is shown that nonequilibrium radiation can be a major source of surface heating during atmospheric entry and a significant factor to heat-shielding requirements. It is also demonstrated that drag-brake concepts have application to a broad range of orbital-transfer missions, because of the favorable trade-offs with aeromaneuvering vehicles in volumetric efficiency, retrothrust plane-change capability, and heat-protection requirements. In addition, the results of this study indicate that the aero-assist technique produces small penalties in vehicle payload capacity for drag-brake concepts, because of the system's heat protection requirements, and is highly attractive relative to all-propulsive orbital-change maneuvers.

Menees, G. P.↗
NASA NTRS1983

Radiation energy receiver for laser and solar propulsion systems

The concept of remotely heating a rocket propellant with a high intensity radiant energy flux is especially attractive due to its high specific impulse and large payload mass capabilities. In this paper, a radiation receiver-thruster which is especially suited to the particular thermodynamic and spectral characteristics of highly concentrated solar energy is proposed. In this receiver, radiant energy is volumetrically absorbed within a hydrogen gas seeded with alkali metal vapors. The alkali atoms and molecules absorb the radiant flux and, subsequently, transfer their internal excitation to hydrogen molecules through collisional quenching. It is shown that such a radiation receiver would outperform a blackbody cavity type receiver in both efficiency and maximum operating temperatures. A solar rocket equipped with such a receiver-thruster would deliver thrusts of several hundred newtons at a specific impulse of 1000 seconds.

Rault, D. F. G.↗
NASA NTRS1982

Accomplishments of the NASA Johnson Space Center portion of the soil moisture project in fiscal year 1981

The NASA/JSC ground scatterometer system was used in a row structure and row direction effects experiment to understand these effects on radar remote sensing of soil moisture. Also, a modification of the scatterometer system was begun and is continuing, to allow cross-polarization experiments to be conducted in fiscal years 1982 and 1983. Preprocessing of the 1978 agricultural soil moisture experiment (ASME) data was completed. Preparations for analysis of the ASME data is fiscal year 1982 were completed. A radar image simulation procedure developed by the University of Kansas is being improved. Profile soil moisture model outputs were compared quantitatively for the same soil and climate conditions. A new model was developed and tested to predict the soil moisture characteristic (water tension versus volumetric soil moisture content) from particle-size distribution and bulk density data. Relationships between surface-zone soil moisture, surface flux, and subsurface moisture conditions are being studied as well as the ways in which measured soil moisture (as obtained from remote sensing) can be used for agricultural applications.

Paris, J. F.↗
NASA NTRS1984

Topography on Ganymede derived from photoclinometry

A fundamental limitation in the quantitative analysis of planetary geomorphology and structural geology results from the absense of topographic data. Among the studies that might be addressed, were such data available, are volumetric and slope relationships of Ionian volcanics, fracture and annealing processes in icy crusts on Europa and Ganymede, and evaluation of viscous relaxation as a means of degrading landforms on Europea, Ganymede, and Callisto. A technique for acquiring topographic data on the Galilean satellites using photoclinometry was developed and applied.

Danielson, G. E.↗
NASA NTRS1984

Use of the Burton-prim-slichter Equation at High Growth Rates

The following must be assumed in order to derive the classic Burton-Prim-Slichter equation for segregation during crystal growth: isobaric, isothermal, isopotential or uncharged species, binary, planar interface, steady state, constant diffusion coefficient in fluid, no diffusion in crystal, no lateral convection within fluid film at interface with complete mixing beyond (stagnant film model), and either density, total concentration or partial molar volumes constant in the fluid phase. In addition, the effective distribution coefficient and the interfacial distribution coefficient must be defined properly. The velocity in the equation is the growth rate times a factor correcting for the difference in volumetric properties between crystal and fluid. The stagnant film thickness is found to be a function of freezing rate, with the precise functionality depending on the type of stirring occurring in the growth fluid.

Wilcox, W. R.↗
NASA NTRS1984

Test Results of a Ten Cell Bipolar Nickel-hydrogen Battery

A study was initiated to design and evaluate a new design concept for nickel-hydrogen cells. This concept involved constructing a battery in a bipolar stack with cells consisting of a one plate for each nickel and hydrogen electrode. Preliminary designs at the system level of this concept promised improvements in both volumetric and gravimetric energy densities, thermal management, life extension, costs, and peak power capability over more conventional designs. Test results were most encouraging. This preprototype battery, built with less than ideal components and hardware, exceeded expectations. A total of 2000 LEO cycles at 80 percent depth of discharge were accrued. A cycle life goal of 30,000 cycles appears achievable with minor design changes. These improvements include advanced technology nickel electrodes, insulated bipolar plates and specifically designed frames to minimize shunt currents. The discharge rate capability of this design exceeds 25C. At the 10C discharge rate, 80% of the battery capacity can be withdrawn in six minutes. This data shows that the bipolar design is well suited for those applications requiring high peak power pulses.

Cataldo, R. L.↗
NASA NTRS1984

Unconventional missile concepts from consideration of varied mission requirements

The characteristics of a series of unconventional missile configurations are reviewed in the light of specific mission requirements, taking volumetric efficiency and aerodynamic performance into account. Cones with and without delta wings, thick delta wings, a semiconical body with delta wings, a ring wing, a flat body with half-ring or swept-parasol wings, a parasol-wing/body with a high/low wing, and monoplanar missiles with circular or elliptical bodies are described and illustrated. Mission requirements discussed include tactical and strategic penetration, maneuverability, load-carrying capability, low detectability, low cost, and ease of carriage and storage. In general, delta configurations offer high speed and good load-carrying ability at low altitudes; parasol configurations give high lift and low drag at high altitude and speed; and monoplanar-elliptical configurations have high lift and low drag with good maneuvering and stability.

Spearman, M. L.↗
NASA NTRS1982

Anomalies within the system - Rochechouart target rock meteorite

Contaminated impact crater formations are pertinent to the study of meteoritic contamination at the Cretaceous-Tertiary boundary and other Ir-enriched layers. Target mixing considerations and volumetric estimates of Rochechouart breccias are presently combined with the geochemistry of both major and siderophile trace elements, to evaluate how the chemistry of the preserved target rock-projectile mixture evolved since deposition. Over 99 percent of the mass of extraterrestrial Ir and Os in preserved formations at Rochechouart is located in suevite-like breccias and impact melts. Hydrothermal alteration and/or weathering are the most likely processes to explain both major and trace element redistribution in Rochechouart formations.

Lambert, P.↗
NASA NTRS1984

The design, fabrication and delivery of a spacelab neutral buoyancy Instrument Pointing System (IPS) mockup

Underwater simulations of EVA contingency operations such as manual jettison, payload disconnect, and payload clamp actuation were used to define crew aid needs and mockup pecularities and characteristics to verify the validity of simulation using the trainer. A set of mockup instrument pointing system tests was conducted and minor modifications and refinements were made. Flight configuration struts were tested and verified to be operable by the flight crew. Tasks involved in developing the following end items are described: IPS gimbal system, payload, and payload clamp assembly; the igloos (volumetric); spacelab pallets, experiments, and hardware; experiment, and hardware; experiment 7; and EVA hand tools, support hardware (handrails and foot restraints). The test plan preparation and test support are also covered.

Vanvalkenburgh, C. N.↗
NASA NTRS1984

The development of a microprocessor-controlled linearly-actuated valve assembly

The development of a proportional fluid control valve assembly is presented. This electromechanical system is needed for space applications to replace the current proportional flow controllers. The flow is controlled by a microprocessor system that monitors the control parameters of upstream pressure and requested volumetric flow rate. The microprocessor achieves the proper valve stem displacement by means of a digital linear actuator. A linear displacement sensor is used to measure the valve stem position. This displacement is monitored by the microprocessor system as a feedback signal to close the control loop. With an upstream pressure between 15 and 47 psig, the developed system operates between 779 standard CU cm/sec (SCCS) and 1543 SCCS.

Wall, R. H.↗
NASA NTRS1985

The application of some lifting-body reentry concepts to missile design

The aerodynamic characteristics of some lifting-body concepts are examined with a view to the applicability of such concepts to the design of missiles. A considerable amount of research has been done in past years with vehicle concepts suitable for manned atmospheric-entry and atmospheric flight. Some of the concepts appear to offer some novel design approaches for missiles for a variety of missions and flight profiles, including long-range orbital/reentry with transatmospheric operation for strategic penetration, low altitude penetration, and battlefield tactical. The concepts considered include right triangular pyramidal configurations, a lenticular configuration, and various 75-degree triangular planform configurations with variations in body camber and control systems. The aerodynamic features are emphasized but some observations are also made relative to other factors such as heat transfer, structures, carriage, observability, propulsion, and volumetric efficiency.

Spearman, M. L.↗
NASA NTRS1985

Jet fuel property changes and their effect on producibility and cost in the U.S., Canada, and Europe

The effects of changes in properties and blending stocks on the refinery output and cost of jet fuel in the U.S., Canada, and Europe were determined. Computerized refinery models that minimize production costs and incorporated a 1981 cost structure and supply/demand projections to the year 2010 were used. Except in the West U.S., no changes in jet fuel properties were required to meet all projected demands, even allowing for deteriorating crude qualities and changes in competing product demand. In the West U.S., property changes or the use of cracked blendstocks were projected to be required after 1990 to meet expected demand. Generally, relaxation of aromatics and freezing point, or the use of cracked stocks produced similar results, i.e., jet fuel output could be increased by up to a factor of three or its production cost lowered by up to $10/cu m. High quality hydrocracked stocks are now used on a limited basis to produce jet fuel. The conversion of U.S. and NATO military forces from wide-cut to kerosene-based jet fuel is addressed. This conversion resulted in increased costs of several hundred million dollars annually. These costs can be reduced by relaxing kerosene jet fuel properties, using cracked stocks and/or considering the greater volumetric energy content of kerosene jet fuel.

Varga, G. M., Jr.↗
NASA NTRS1985

The application of some lifting-body reentry concepts to missile design

The aerodynamic characteristics of some lifting-body concepts are examined with a view to the applicability of such concepts to the design of missiles. A considerable amount of research has been done in past years with vehicle concepts suitable for manned atmospheric-entry and atmospheric flight. Some of the concepts appear to offer some novel design approaches for missiles for a variety of missions and flight profiles, including long-range orbital/reentry with transatmospheric operation for strategic penetration, low altitude penetration, and battlefield tactical. The concepts considered include right triangular pyramidal configurations, a lenticular configuration, and various 75-degree triangular planform configurations with variations in body camber and control systems. The aerodynamic features are emphasized but some observations are also made relative to other factors such as heat transfer, structures, carriage, observability, propulsion, and volumetric efficiency.

Spearman, M. L.↗
NASA NTRS1984

Structure function analyses of mesoscale VAS retrievals

Structure function analyses are used for a comparison of two VAS retrieval procedures, one obtained using a physical inversion technique and the other from a linear regression technique. Results from both procedures are evaluated and compared with those from a special mesoscale network of radiosonde stations, operated during March 6, 7, 1982 as part of the AVE-VAS field experiment. It is shown that both types of VAS retrievals underestimate the magnitudes of mean nondirectional gradients that are detected by the mesoscale radiosonde network. This result is expected since the VAS provides a volumetric sample of the atmosphere.

Meyer, P. J.↗
NASA NTRS1984

The NASA Lithium Technology Program

NASA is sponsoring research to develop advanced primary and secondary lithium cells. Lithium cells are conducive to aerospace use because they have high specific energy, volumetric energy density, and long storage capability. The primary cell research is centered on the Li/SOCl2 system. It is in the late development stage and all effort is being placed on resolving safety problems. The secondary cell, which is in the development stage, is the Li/TiS2 system. The objective is to produce a 100 wh/kg cell capable of operating in a geosynchronous orbit for 10 years. The development of improved conductivity polymeric films for electrochemical use is also being investigated. The lightweight batteries will have many applications in space and are already being prepared for the 1986 Galileo mission to Jupiter.

Halpert, G.↗
NASA NTRS1985

'Alfven wing' models of the induced electrical current system at Io - A probe of the ionosphere of Io

A novel class of models of the Alfven wing interaction between the Io plasma torus and Io's ionosphere has been developed and used to compute the magnetic field fluctuations at the position of the Voyager 1 flyby. These computations of the magnetic field signature are compared with the magnetic field measurements made during the flyby, and the differences between the model and observations are used as a probe of the structure of Io's ionosphere. The results of this model fitting indicate that a significant atmospheric neutral column density is required over a major part of the trailing hemisphere. This can be consistent with the cold-trap model for Io's neutral atmoshpere only if the major plumes near the center of the trailing hemisphere provide significant volumetric coverage. The Io plasma torus charged-mass density required for a proper match to the data is larger than earlier estimates based on the width of the Alfven wing signature.

Herbert, F.↗
NASA NTRS1985

Bulk Formation of Metallic Glasses and Amorphous Silicon from the Melt

By using metallic glass compositions with a high relative glass transition temperature, such as Pd40Ni40P20, homogeneous nucleation also becomes negligible. Large (5g) masses of this alloys were obtained using a molten B2O3 flux. Presently, bulk glass formation in iron based glasses is being investigated. It is expected that if an undercooling of about 250K can be achieved in a Ge or Si melt, formation of the amorphous semiconductor phase (rather than the crystal) may be kinetically favored. The volumetric behavior of undercooled liquid Ga droplet dispersion is investigated by dilatometry. A theoretical model (both analytical and numerical) was developed for transient nucleation in glass forming melts. The model, originally designed for isothermal conditions, was extended to continuous quenching. It is being applied to glass formation in various metallic and oxide systems. A further refinement will be the inclusion of diffusion controlled interfacial rearrangements governing the growth of the crystal embryos.

Spaepen, F.↗