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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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All sourcesNASA NTRSDOE OSTI
NASA NTRS1976

Web-dendritic ribbon growth

A web furnace was constructed for pulling dendritic-web samples. The effect of changes in the furnace thermal geometry on the growth of dendritic-web was studied. Several attempts were made to grow primitive dendrites for use as the dendritic seed crystals for web growth and to determine the optimum twin spacing in the dendritic seed crystal for web growth. Mathematical models and computer programs were used to determine the thermal geometries in the susceptor, crucible melt, meniscus, and web. Several geometries were determined for particular furnace geometries and growth conditions. The information obtained was used in conjunction with results from the experimental growth investigations in order to achieve proper conditions for sustained pulling of two dendrite web ribbons. In addition, the facilities for obtaining the following data were constructed: twin spacing, dislocation density, web geometry, resistivity, majority charge carrier type, and minority carrier lifetime.

Hilborn, R. B., Jr.↗
NASA NTRS1976

Energy consumption characteristics of transports using the prop-fan concept

The fuel saving and economic potentials of the prop-fan high-speed propeller concept were evaluated for twin-engine commercial transport airplanes designed for 3333.6 km range, 180 passengers, and Mach 0.8 cruise. A fuel saving of 9.7% at the design range was estimated for a prop-fan airplane having wing-mounted engines, while a 5.8% saving was estimated for a design having the engines mounted on the aft body. The fuel savings and cost were found to be sensitive to the propeller noise level and to aerodynamic drag effects due to wing-slipstream interaction. Uncertainties in these effects could change the fuel savings as much as + or - 50%. A modest improvement in direct operating cost (DOC) was estimated for the wing-mounted prop-fan at current fuel prices. This improvement could become substantial in the event of further relative increases in the price of oil. The improvement in DOC requires the achievement of the nominal fuel saving and reductions in propeller and gearbox maintenance costs relative to current experience.

Source record↗
NASA NTRS1976

Effect of atmospheric parameters on silicon cell performance

The effects of changing atmospheric parameters on the performance of a typical silicon solar cell were calculated. The precipitable water vapor content, airmass and turbidity were varied over wide ranges and the normal terrestrial distribution of spectral irradiance was studied. The cell short-circuit current was then computed for each spectral irradiance distribution using the cell spectral response. Data are presented in the form of calibration number (cell current/incident irradiance) vs. water vapor content or turbidity.

Curtis, H. B.↗
NASA NTRS1977

The effect of ambient conditions on carbon monoxide emissions from an idling gas turbine combustor

A test program employing a gas turbine combustor is outlined; the results of which quantize the effects of changes in ambient temperature and humidity on carbon monoxide emissions at simulated idle operating conditions. A comparison of the experimental results with analytical results generated by a kinetic model of the combustion process, and reflecting changing ambient conditions, is given. It is demonstrated that for a complete range of possible ambient variations, significant changes do occur in the amount of carbon monoxide emitted by a gas turbine at idle, and that the analytical model is reasonably successful in predicting changes.

Subramanian, A. K.↗
NASA NTRS1977

Comparative studies of Lunar, Martian, and Mercurian craters and plains

Lunar features provide a valuable interpretation data base for comparison with features on other planets which are believed to have been formed by the cratering process. The paper adopts the comparative approach by examining the smooth plains of the moon and Mercury, with special emphasis on crater degradation on the moon, Mercury, and Mars. A possible cause for the observed deficiency of craters with diameters no more than 50 km on certain areas of lunar uplands and on the entire uplands of Mercury and Mars is discussed. It is suggested that pertinent differences can be predicted on the basis of new concepts for production population and of effects of changes in planetary conditions on the secondary cratering process. It is concluded that the deficiency of craters with diameters no more than 50 km on parts of the lunar uplands and on the Mercurian and Martian uplands may be evidence for a deficiency in production of primary craters in this size range. Origin of the late heavy bombardment in the inner solar system is examined.

Oberbeck, V. R.↗
NASA NTRS1977

Possible origins of time variability in Jupiter's outer magnetosphere. I - Variations in solar wind dynamic pressure. II - Variations in solar wind magnetic field

Attention is given to the effect of changes in the dynamic pressure of the solar wind on the structure of a centrifugally driven planetary wind from Jupiter. It is suggested that dynamic pressure variations can induce a transition between a super-Alfvenic wind and a sub-Alfvenic wind breeze on Jupiter's dayside. This could possibly account for the observed large-scale changes in the structure of Jupiter's outer magnetosphere. An attempt is then made to conceptually merge planetary wind models of Jupiter's outer magnetosphere with reconnection models of Jupiter's outer magnetosphere.

Coroniti, F. V.↗
NASA NTRS1977

Effect of flap deflection on the lift coefficient of wings operating in a biplane configuration

Biplane models with a lift flap were tested in a wind tunnel to study the effect of flap deflection on the aerodynamic coefficient of the biplane as well as of the individual wings. Optimization of the position flap was carried out, and the effect of changes in the chord length of the lower wing was determined for the aerodynamic structure of a biplane with a lift flap on the upper wing.

Stasiak, J.↗
NASA NTRS1977

Wind-tunnel tests of wide-chord teetering rotors with and without outboard flapping hinges

Wind tunnel tests of aeroelastically designed helicopter rotor models were conducted to obtain rotor aerodynamic performance and dynamic response data pertaining to two-bladed teetering rotors with a wider chord and lower hover tip speed than currently employed on production helicopters. The effects of a flapping hinge at 62 percent radius were also studied. Finally, the effects of changing tip mass on operating characteristics of the rotor with the outboard flapping hinge were examined. The models were tested at several shaft angles of attack for five advance ratios, 0.15, 0.25, 0.35, 0.40, and 0.45. For each combination of shaft angle and advance ratio, the rotor lift was varied over a wide range to include simulated maneuver conditions. At each test condition, rotor aerodynamic performance and dynamic response data were obtained. From these tests, it was found that wide-chord rotors may be subject to large control forces. An outboard flapping hinge may be used to reduce beamwise bending moments over a significant part of the blade radius without significantly affecting the chordwise bending moments.

Weller, W. H.↗
NASA NTRS1977

Some effects of acceleration in man and chimpanzees

Early physiologic experiments using dogs and humans in centrifuges are reviewed. Because of the close similarity between the shape and dimensions of the thoraces of chimpanzees and humans, the former were used to obtain roentgenograms and photokymographic recordings of multiple physiologic variables before and during exposure to +5.8 Gy to study the effects of changes in the gravitational-inertial force environment on the cardiovascular and pulmonary systems during long duration space flight. A computer-controlled sciscanning system was used to obtain a two dimensional map of the amount of radiation emanating from the dorsal and ventricle surfaces after insertion of radioactive microspheres in the right ventricle. By using four different batches of microspheres tagged with isotopes of different energies, the spatial distribution of pulmonary blood flow under four conditions was determined.

Wood, E. H.↗
NASA NTRS1977

Effect of fuel properties on performance of single aircraft turbojet combustor at simulated idle, cruise, and takeoff conditions

The performance of a single-can JT8D combustor was investigated with a number of fuels exhibiting wide variations in chemical composition and volatility. Performance parameters investigated were combustion efficiency, emissions of CO, unburned hydrocarbons and nitrogen oxides, as well as liner temperatures and smoke. The most pronounced effects of changes in fuel composition were observed at simulated cruise and takeoff conditions where smoke and liner temperatures increased significantly as the hydrogen content of the fuel decreased. At the simulated idle condition, emissions of CO and unburned hydrocarbons increased slightly and, accordingly, combustion efficiencies decreased slightly as the hydrogen content of the fuels decreased.

Butze, H. F.↗
NASA NTRS1978

Acoustical effects of blade tip shape changes on a full scale helicopter rotor in a wind tunnel

Four tip shapes were tested. They were rectangular, swept, tapered, and swept-tapered. The measured data covered a wide range of operating conditions. The range of advancing tip Mach numbers were between 0.72 to 0.96, and the advance ratios were from 0.2 to 0.375. At low and moderate advancing tip Mach number, the data in the dbA scale appear to indicate the swept tip is the quietest, swept tapered the second, tapered third and rectangular the most noisy. Above an advancing tip Mach number of about 0.89, a distinct acoustical pulse can be observed, which dominates the acoustical waveform. The pulse shape is symmetric at moderate tip Mach number, changing to a sawtooth shape at high advancing tip Mach numbers. Based on the amplitude of the impulsive noise, it appears the swept-tapered tip is the quietest, tapered tip the second, swept tip third and square tip the most noisy. The data presented in this report should be useful as data bases for modeling and evaluating helicopter impulsive noise.

Lee, A.↗
NASA NTRS1978

Demand modelling of passenger air travel: An analysis and extension. Volume 1: Background and summary

The framework for a model of travel demand which will be useful in predicting the total market for air travel between two cities is discussed. Variables to be used in determining the need for air transportation where none currently exists and the effect of changes in system characteristics on attracting latent demand are identified. Existing models are examined in order to provide insight into their strong points and shortcomings. Much of the existing behavioral research in travel demand is incorporated to allow the inclusion of non-economic factors, such as convenience. The model developed is characterized as a market segmentation model. This is a consequence of the strengths of disaggregation and its natural evolution to a usable aggregate formulation. The need for this approach both pedagogically and mathematically is discussed.

Jacobson, I. D.↗
NASA NTRS1977

Vertical lifting of ionization during geomagnetic storms from satellite measurements of ion composition

Magnetic-storm phenomena at low latitudes are discussed based on ion-composition /O(+), H(+), He(+)/ and electron- and ion-temperature measurements from the OGO-4 and Isis-2 satellites. For the moderately severe storms considered, the effects of changes in the neutral composition and in the neutral and plasma temperatures are discussed, and it is shown that these changes would not produce the observed O(+) increase during storms at low latitudes. It is suggested that the observed increase in O(+) in the topside region is a manifestation of the vertical lifting of ionization of the F-layer. The argument in favor of vertical lifting is further substantiated by the observed changes in the F-region critical frequency and the height parameters.

Goel, M. K.↗
NASA NTRS1978

Fuel saving potential of Mach 0.8 twin engine prop-fan transports

The fuel saving and economic potentials of the prop-fan high-speed propeller concept have been evaluated for twin-engine commercial transport airplanes designed for 3333.6 km range, 180 passengers, and Mach 0.8 cruise. A fuel saving of 9.7% at the design range was estimated for a prop-fan aircraft having wing-mounted engines, while a 5.8% saving was estimated for a design having the engines mounted on the aft body. The fuel savings and cost were found to be sensitive to the propeller noise level and to aerodynamic drag effects due to wing-slipstream interaction. Uncertainties in these effects could change the fuel savings as much as plus or minus 50%. A modest improvement in direct operating cost was estimated for the wing-mounted prop-fan at current fuel prices.

Davenport, F. J.↗
NASA NTRS1977

The correction of Landsat data for the effects of haze, sun angle, and background reflectance

A technique has been developed for simulating the effects of haze, sun angle, and background reflectance in Landsat data and correcting for them. The atmospheric model assumes a two-layer atmosphere: a Rayleigh scattering molecular layer and a Mie scattering haze layer next to the earth's surface. Reflection and transmission matrices describe the reflection and transmission properties of the plane parallel scattering layers. The multispectral scanner response is computed for various values of the parameters under evaluation. This yields expressions for Landsat gray-scale levels used for determining the effect of changes in any parameter. The Atmospheric Correction computer program is used to determine the haze level from the data, to compute the reflectance, and to interpolate in order to find the correction coefficients necessary to make the desired correction.

Potter, J. F.↗
NASA NTRS1978

The influence of vehicle aerodynamic and control response characteristics on driver-vehicle performance

The effects of changes in understeer, control sensitivity, and location of the lateral aerodynamic center of pressure (c.p.) of a typical passenger car on the driver's opinion and on the performance of the driver-vehicle system were studied in a moving-base driving simulator. Twelve subjects with no prior experience on the simulator and no special driving skills performed regulation tasks in the presence of both random and step wind gusts.

Alexandridis, A. A.↗
NASA NTRS1977

Multipurpose Panel Display Device Investigation

A multipurpose panel was developed to provide a flexible control and a LED display panel with easily changeable nomenclature for use in applications where panel space is limited, but where a number of similar subsystems must be controlled, or where basic panel nomenclature and functions must be changed rapidly, as in the case of between mission changes of space shuttle payloads. In the first application, panel area limitations are overcome by time sharing a central control panel among several subsystems. In the latter case, entire control panel changes are effected by simply replacing a memory module, thereby reducing the extent of installation and checkout procedures between missions. Several types of control technologies (other than LED's) which show potential in meeting criteria for overcoming limitations of the panel are assessed.

Sliwa, R.↗
NASA NTRS1978

Liquid hydrogen tankage design

For this, the tankage experienced only minor thermal loadings and flight loads, hence, the predominate loading was the tank pressurization. Since the tanks were basically tension designed, the fatigue and damage tolerance criteria played the most important part in the overall design of the tank. Sensitivity factors were generated for the reference LH2-fueled airplane to provide a basis for evaluation of the effects of changes from the baseline design. For example, the various candidate insulation systems and tank structural concepts offer tradeoffs of the tankage offset distance (distance between exterior surface to tank) and weight. As the offset varies, the aircraft fuselage length must change to provide the required fuel volume within the fixed fuselage cross-section and hence the sensitivity on the aircraft DOC could be assessed.

Davis, G. W.↗