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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 1,621 records · Page 90
All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

Deformation mechanics of deep surface flaw cracks

A combined analytical and experimental program was conducted to determine the deformation characteristics of deep surface cracks in Mode I loading. An approximate plane finite element analysis was performed to make a parameter study on the influence of crack depth, crack geometry, and stress level on plastic zones, crack opening displacement, and back surface dimpling in Fe-3Si steel and 2219-T87 aluminum. Surface replication and profiling techniques were used to examine back surface dimple configurations in 2219-T87 aluminum. Interferometry and holography were used to evaluate the potential of various optical techniques to detect small surface dimples on large surface areas.

Francis, P. H.↗
NASA NTRS1972

Heat pipe applications for the space shuttle.

Discussion of six specific applications for heat pipe (HP) devices on the space shuttle. These applications were chosen from 27 concepts formulated as part of a study to evaluate the potential benefits associated with HP use. The formulation process is briefly described along with the applications which evolved. The bulk of the discussion deals with the 'top' six - namely, HP radiators for waste heat rejection, an HP augmented cold rail, an HP circuit for electronic equipment cooling, modular heat sink for control of remote packages, an HP temperature control for compartments, and air-cooled equipment racks. The philosophy, physical design details, and performance data are presented for each concept along with a comparison with the baseline design where applicable.

Tawil, M.↗
NASA NTRS1973

Advanced definition study for the determination of atmospheric ozone using the satellite eclipse technique

A study was made to evaluate the potential for remote ground-based measurement of upper atmospheric ozone by determining the absorption ratio of selected narrow bands of sunlight as reflected by satellites while passing into eclipse, using the NASA Mobile Satellite Photometric Observatory (MOSPO). Equipment modifications to provide optimum performance were analyzed and recommendations were made for improvements to the system to accomplish this. These included new sensor tubes, pulse counting detection circuitry, filters, beam splitters and associated optical revision, along with an automatic tracking capability plus corresponding operational techniques which should extend the overall measurement capability to include use of satellites down to 5th magnitude.

Emmons, R.↗
NASA NTRS1974

Regional agriculture surveys using ERTS-1 data

The Center for Remote Sensing Research has conducted studies designed to evaluate the potential application of ERTS data in performing agricultural inventories, and to develop efficient methods of data handling and analysis useful in the operational context for performing large area surveys. This work has resulted in the development of an integrated system utilizing both human and computer analysis of ground, aerial, and space imagery, which has been shown to be very efficient for regional crop acreage inventories. The technique involves: (1) the delineation of ERTS images into relatively homogeneous strata by human interpreters, (2) the point-by-point classification of the area within each strata on the basis of crop type using a human/machine interactive digital image processing system; and (3) a multistage sampling procedure for the collection of supporting aerial and ground data used in the adjustment and verification of the classification results.

Draeger, W. C.↗
NASA NTRS1974

A study program on large aperture electronic scanning phased array antennas for the shuttle imaging microwave system

Fundamental phased array theory and performance parameters are discussed in terms of their application to microwave radiometry, and four scanning phased arrays representing current examples of state-of-the-art phased array technology are evaluated for potential use as components of the multispectral antenna system for the space shuttle imaging microwave system (SIMS). A discussion of problem areas, both in performance and fabrication is included, with extrapolations of performance characteristics for phased array antennas of increased sizes up to 20 m by 20 m. The possibility of interlacing two or more phased arrays to achieve a multifrequency aperture is considered, and, finally, a specific antenna system is recommended for use with SIMS.

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NASA NTRS1973

Linear rocket engine design-fabrication-testing

A new rocket engine concept that is presently being evaluated offers significant performance, cost, and configurational advantages. The Linear Rocket Engine System, (LRES) combines the unique performance and operational advantages of the aerospike nozzle with the configuration versatility of low cost modular combustors, which results in a high-performance rocket engine package designed specifically for use in advanced configuration vehicles. This paper describes the design, fabrication, and testing of the LRES concept to evaluate its potential for vehicle integration. The program was conducted under the sponsorship of NASA's Marshall Space Flight Center.

Fuller, P. N.↗
NASA NTRS1974

Space shuttle structural integrity and assessment study

Potential nondestructive evaluation (NDE) requirements for the space shuttle vehicle during structural inspection in the refurbishment/turnaround period, are defined. Data are given on NDE limitations and defect characterization by the process. Special attention was given to the determination of fatigue cracks, stress corrosion cracks, corrosion, and adhesive disbonds of airframes.

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NASA NTRS1974

Small scale thematic mapping - A case for radar imagery

Small scale thematic maps (1:250,000 and smaller) of physical and cultural phenomena manifested on the landscape are a major concern to scientists and investigators in diverse disciplines. A strip of K-band radar imagery consisting of a traverse from eastern Minnesota to northern Utah was employed to evaluate the potential of radar imagery for small scale land use mapping. In the course of this investigation, it was discovered that certain borders derived from radar imagery were compatible with borders found on the nonland use thematic maps used for comparison. Specifically, numerous borders and regions of small scale maps of landforms, soils, vegetation, and geology are found to be similar to the radar land use regions. Although far from conclusive it appears that radar imagery can be employed in the small scale mapping of landforms and possibly for mapping physiognomic or economic vegetation.

Henderson, F. M.↗
NASA NTRS1975

Design of short haul aircraft for fuel conservation

Current jet fuel prices of twice the 1972 level have significantly changed the characteristics of airplane design for best economy. The results of a contract with the NASA Ames Advanced Concepts and Missions Division confirmed the economic desirability of lower design cruise speeds and higher aspect-ratio wings compared to designs developed in the by-gone era of low fuel price. Evaluation of potential fuel conservation for short-haul aircraft showed that an interaction of airfoil technology and desirable engine characteristics is important: the supercritical airfoil permits higher aspect ratio wings with lower sweep; these, in turn, lower the cruise thrust requirements so that engines with higher bypass ratios are better matched in terms of lapse rate; lower cruise speeds (which are also better for fuel and operating cost economy) push the desired bypass ratio up further. Thus, if fuel prices remain high, or rise further, striking reductions in community noise level can be achieved as a fallout in development of a 1980s airplane and engine. Analyses are presented of developmental trends in the design of short-haul aircraft with lower cruise speeds and higher aspect-ratio wings, and the effects on fuel consumption of design field length, powered lift concepts, and turboprop as well as turbofan propulsion are discussed.

Bowden, M. K.↗
NASA NTRS1975

A general aerodynamic approach to the problem of decaying or growing vibrations of thin, flexible wings with supersonic leading and trailing edges and no side edges

Indicial aerodynamic influence coefficients were evaluated from potential theory for a thin, flexible wing with supersonic leading and trailing edges only. The analysis is based on the use of small surface areas in which the downwash is assumed uniform. Within this limitation, the results are exact except for the restriction of linearized theory. The areas are not restricted either to square boxes or Mach boxes. A given area may be any rectangle or square which may or may not be cut by the Mach forecone, and any area can be used anywhere in the forecone without loss of accuracy.

Warner, R. W.↗
NASA NTRS1975

Investigation of the Centaur boost pump overspeed condition at main engine shutdown on the Titan Centaur TC-2 flight

An investigation was conducted to evaluate a potential boost pump overspeed condition which could exist on the Titan/Centaur launch vehicle after main engine shut-off. Preliminary analyses indicated that the acceleration imparted to the unloaded boost pump-turbine assembly, caused by purging residual hydrogen peroxide from the turbine supply lines, could result in a pump-turbine overspeed. Previous test experience indicated that turbine damage occurs at speeds in excess of 75,000 rpm. Detailed theoretical analyses, in conjunction with pump tests, were conducted to establish the maximum pump-turbine speed at main engine shut-off. The analyses predicted a maximum speed of 68,000 rpm. Testing showed the pump-turbine speed to be 66,700 rpm in the overspeed condition. Inasmuch as both the analysis and tests showed the overspeed to be sufficiently less than the speed at which damage could occur, it was concluded that no corrective action would be required for the launch vehicle.

Baud, K. W.↗
NASA NTRS1974

Precision Attitude Determination System (PADS) system design and analysis: Single-axis gimbal star tracker

The feasibility is evaluated of an evolutionary development for use of a single-axis gimbal star tracker from prior two-axis gimbal star tracker based system applications. Detailed evaluation of the star tracker gimbal encoder is considered. A brief system description is given including the aspects of tracker evolution and encoder evaluation. System analysis includes evaluation of star availability and mounting constraints for the geosynchronous orbit application, and a covariance simulation analysis to evaluate performance potential. Star availability and covariance analysis digital computer programs are included.

Source record↗
NASA NTRS1976

The effect of helicopter main rotor blade phasing and spacing on performance, blade loads, and acoustics

The performance, blade loads, and acoustic characteristics of a variable geometry rotor (VGR) system in forward flight and in a pullup maneuver were determined by the use of existing analytical programs. The investigation considered the independent effects of vertical separation of two three-bladed rotor systems as well as the effects of azimuthal spacing between the blades of the two rotors. The computations were done to determine the effects of these parameters on the performance, blade loads, and acoustic characteristics at two advance ratios in steady-state level flight and for two different g pullups at one advance ratio. To evaluate the potential benefits of the VGR concept in forward flight and pullup maneuvers, the results were compared as to performance, oscillatory blade loadings, vibratory forces transmitted to the fixed fuselage, and the rotor noise characteristics of the various VGR configurations with those of the conventional six-bladed rotor system.

Gangwani, S. T.↗
NASA NTRS1975

Multiple slot skin friction reduction

The paper investigates analytically the effect of multiple slot injection on skin friction for a representative fuselage shape (ogive-cylinder body) and evaluates the potential of slot injection as a drag reduction system in subsonic flow. Typical CTOL cruise flight conditions (Mach number equals 0.82 at altitudes of 11 km) were adopted for a fuselage 67.06 m in length and with maximum diameter of 7.32 m. The numerical method of Price and Harris (1972) was used to calculate the boundary-layer characteristics up to the first slot, while the finite-difference method of Beckwith and Bushnell (1971) was used to calculate the velocity profile downstream of one, three, five, or ten slots. An integral expression is proposed for characterizing skin friction reduction effectiveness, and it is seen that large reductions in viscous drag (50%) are available through slot injection. Skin friction reduction is improved by increasing the number of injection slots but at a diminishing rate.

Howard, F. G.↗
NASA NTRS1976

The Viking Orbiter Visual Imaging Subsystem

Two Viking spacecraft each consisting of an Orbiter and a Lander are on trajectories toward Mars with arrival dates in June and August 1976. A Visual Imaging Subsystem consisting of two slow-scan television cameras forms part of the scientific payload of each Orbiter. These cameras will be used to evaluate the potential landing sites on Mars and to conduct other scientific investigations of the planet. The camera system described in this paper was subjected to an extensive test and calibration program prior to launch. Based on this calibration and subsequent analyses, absolute photometric accuracies of 8.0% may be achieved. Surface resolution exceeding 100 meters will be achieved from the periapsis portion of the Viking orbits. The inherent geometric accuracies of the Orbiter cameras supersede those of previous planetary missions. The analyses of images acquired during the cruise phase of the mission confirms that the cameras have survived the rigors of launch and are performing in a manner consistent with the prelaunch calibrations.

Wellman, J. B.↗
NASA NTRS1977

Advanced technology for minimum weight pressure vessel system

Bosses were made of fiber/resin composite materials to evaluate their potential in lightweight pressure vessels. An approximate 25% weight savings over the standard aluminum boss was achieved without boss failures during burst tests. Polymer liners and metal liners are used in fiber composite pressure vessels for containment of gases. The internal support of these liners required during the filament winding process has previously been provided by dissolvable salt mandrels. An internal pressurization technique has been developed which allows overwinding the liner without other means of support and without collapse. Study was made of several additional concepts including styrene/Saran, styrene/flexible epoxy.

Hamstad, M. A.↗
NASA NTRS1976

A preliminary assessment of the feasibility of deriving liquid and gaseous fuels from grown and waste organics

An estimate is obtained of the yearly supply of organic material for conversion to fuels, the energy potential is evaluated, and the fermentation and pyrolysis conversion processes are discussed. An investigation is conducted of the estimated cost of fuel from organics and the conclusions of an overall evaluation are presented. It is found that climate, land availability and economics of agricultural production and marketing, food demand, fertilizer shortage, and water availability combine to cast doubts on the feasibility of producing grown organic matter for fuel, in competition with food, feed, or fiber. Less controversial is the utilization of agricultural, industrial, and domestic waste as a conversion feedstock. The evaluation of a demonstration size system is recommended.

Graham, R. W.↗