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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 217 records · Page 12
All sourcesNASA NTRSDOE OSTI
NASA NTRS1977

Experimental design studies and flow visualization of proportional laminar-flow fluidic amplifiers

The effects of certain parameter variations on the performance characteristics of laminar, proportional, jet-deflection fluidic amplifiers were studied. The matching and staging of amplifiers to obtain high pressure gain was included, but dynamic effects were not. The parameter variations considered were aspect ratio, setback, control length, splitter distance, receiver-duct width, width of center-vent duct, and bias pressure. Usable pressure gains of 19 per stage were achieved, and 5 amplifier stages were integrated to yield an overall pressure gain of 2,000,000.

Hellbaum, R. F.↗
NASA NTRS1977

Optimal estimation and attitude control of a solar electric propulsion spacecraft

Established procedures of linear, quadratic, Gaussian optimal estimation and control are developed and interpreted for their application to the problem of attitude control of spacecraft with dynamically significant elastic appendages. Results are presented both in general terms and for specific application to a solar electric spacecraft. Comparisons are made between alternative coordinate systems, and a realistic range of design parameters is considered. For single axis control, system evaluation is accomplished by simulation of a fifteenth-order spacecraft plant with alternative second-order, fourth-order, and sixth-order constant gain estimators. Results point out the importance of modeling errors.

Larson, V.↗
NASA NTRS1978

Orbit IMU alinement interpretation of onboard display data

The space shuttle inertial measurement unit (IMU) alinement algorith was examined to determine the most important alinement starpair selection criterion. Three crew displayed parameters were considered: (1) the results of the separation angle difference (SAD) check for each starpair; (2) the separation angle of each starpair; and (3) the age of each star measurement. It was determined that the SAD for each pair cannot be used to predict the IMu alinement accuracy. If the age of each star measurement is less than approximately 30 minutes, time is a relatively unimportant factor and the most important alinement pair selection criterion is the starpair separation angle. Therefore, when there are three available alinement starpairs and all measurements were taken within the last 30 minutes, the pair with the separation angle closest to 90 degrees should be selected for IMU alinement.

Corson, R.↗
NASA NTRS1978

Simulation and flight evaluation of a head-up landing aid for general aviation

A head-up general aviation landing aid called a landing site indicator (LASI) was tested in a fixed-base, visual simulator and in an airplane to determine the effectiveness of the LASI. The display, which had a simplified format and method of implementation, presented to the pilot in his line of sight through the windshield a graphic representation of the airplane's velocity vector. In each testing model (simulation of flight), each of 4 pilots made 20 landing approaches with the LASI and 20 approaches without it. The standard deviations of approach and touchdown parameters were considered an indication of pilot consistency. Use of the LASI improved consistency and also reduced elevator, aileron, and rudder control activity. Pilots' comments indicated that the LASI reduced work load. An appendix is included with a discussion of the simulator effectiveness for visual flight tasks.

Harris, R. L., Sr.↗
NASA NTRS1978

Study of heat sink thermal protection systems for hypersonic research aircraft

The feasibility of using a single metallic heat sink thermal protection system (TPS) over a projected flight test program for a hypersonic research vehicle was studied using transient thermal analyses and mission performance calculations. Four materials, aluminum, titanium, Lockalloy, and beryllium, as well as several combinations, were evaluated. Influence of trajectory parameters were considered on TPS and mission performance for both the clean vehicle configuration as well as with an experimental scramjet mounted. From this study it was concluded that a metallic heat sink TPS can be effectively employed for a hypersonic research airplane flight envelope which includes dash missions in excess of Mach 8 and 60 seconds of cruise at Mach numbers greater than 6. For best heat sink TPS match over the flight envelope, Lockalloy and titanium appear to be the most promising candidates

Vahl, W. A.↗
NASA NTRS1980

Electric-car simulation

PARAMET, interactive simulation program for parametric studies of electric vehicles, guides user through simulation by menu and series of prompts for input parameters. Program considers aerodynamic drag, rolling resistance, linear and rotational acceleration, and road gradient as forces acting on vehicle.

Chapman, C. P.↗
NASA NTRS1979

Analysis of some aerodynamic characteristics due to wing-jet interaction

The results of two separate theoretical investigations are presented. A program was used which is capable of predicting the aerodynamic characteristics of both upper-surface blowing (USB) and over-wing blowing (OWB) configurations. A theoretical analysis of the effects of over-wing blowing jets on the induced drag of a 50 deg sweep back wing was developed. Experiments showed net drag reductions associated with the well known lift enhancement due to over-wing blowing. The mechanisms through which this drag reduction is brought about are presented. Both jet entrainment and the so called wing-jet interaction play important roles in this process. The effects of a rectangular upper-surface blowing jet were examined for a wide variety of planforms. The isolated effects of wing taper, sweep, and aspect ratio variations on the incremental lift due to blowing are presented. The effects of wing taper ratio and sweep angle were found to be especially important parameters when considering the relative levels of incremental lift produced by an upper-surface blowing configuration.

Fillman, G. L.↗
NASA NTRS1979

Design and test of a prototype scale ejector wing

A two dimensional momentum integral analysis was used to examine the effect of changing inlet area ratio, diffuser area ratio, and the ratio of ejector length to width. A relatively wide range of these parameters was considered. It was found that for constant inlet area ratio the augmentation increases with the ejector length, and for constant length: width ratio the augmentation increases with inlet area ratio. Scale model tests were used to verify these trends and to examine th effect of aspect ratio. On the basis of these results, an ejector configuration was selected for fabrication and testing at a scale representative of an ejector wing aircraft. The test ejector was powered by a Pratt-Whitney F401 engine developing approximately 12,000 pounds of thrust. The results of preliminary tests indicate that the ejector develops a thrust augmentation ratio better than 1.65.

Mefferd, L. A.↗
NASA NTRS1980

A theoretical model of phase changes of a klystron due to variation of operating parameters

A mathematical model for phase changes of the VA-876 CW klystron amplifier output is presented and variations of several operating parameters are considered. The theoretical approach to the problem is based upon a gridded gap modeling with inclusion of a second order correction term so that actual gap geometry is reflected in the formulation. Physical measurements are contrasted to theoretical calculations.

Kupiszewski, A.↗
NASA NTRS1979

Phase 1 of the near term hybrid passenger vehicle development program, appendix A. Mission analysis and performance specification studies. Volume 2: Appendices

A handy reference for JPL minimum requirements and guidelines is presented as well as information on the use of the fundamental information source represented by the Nationwide Personal Transportation Survey. Data on U.S. demographic statistics and highway speeds are included along with methodology for normal parameters evaluation, synthesis of daily distance distributions, and projection of car ownership distributions. The synthesis of tentative mission quantification results, of intermediate mission quantification results, and of mission quantification parameters are considered and 1985 in place fleet fuel economy data are included.

Traversi, M.↗
NASA NTRS1980

Flight Mechanics/Estimation Theory Symposium

Methods of determining satellite orbit and attitude parameters are considered. The Goddard Trajectory Determination System, the Global Positioning System, and the Tracking and Data Relay Satellites are among the satellite navigation systems discussed. Satellite perturbation theory, orbit/attitude determination using landmark data, and star measurements are also covered.

Fuchs, A. J.↗
NASA NTRS1980

Spectrophotovoltaic orbital power generation

A system with 1000 : 1 concentration ratio is defined, using a cassegrain telescope as the first stage concentration (270 x) and compound parabolic concentrators (CPC) for the second stage concentration of 4.7 x for each spectral band. Using reported state of the art (S.O.A.) solar cells device parameters and considering structural losses due to optics and beamsplitters, the efficiencies of one to four cell systems were calculated with efficiencies varying from approximately 22% to 30%. Taking into account cost of the optics, beamsplitter, radiator, and the cost of developing new cells the most cost effective system is the GaAs/Si system.

Knowles, G.↗
NASA NTRS1980

Inlet flow distortion in turbomachinery

A single stage axial compressor with distorted inflow is studied. The inflow distortion occurs far upstream and may be a distortion in stagnation temperature, stagnation pressure or both. The blade rows are modeled as semi-actuator disks. Losses, quasi-steady deviation angles, and reference incidence correlations are included in the analysis. Both subsonic and transonic relative Mach numbers are considered. A parameter study is made to determine the influence of such variables as Mach number and swirl angle on the attenuation of the distortion.

Seidel, B. S.↗
NASA NTRS1982

Laser power conversion system analysis

Orbit to orbit and orbit to ground laser power conversion systems and power transfer are discussed. A system overview is presented. Pilot program parameters are considered: SLPS assumptions are listed, a laser SPS overview is presented, specifications are listed, and SLPS coats are considered.

Source record↗
NASA NTRS1982

Comparison of storm-time changes of geomagnetic field at ground and at MAGSAT altitudes, part 2

Geomagnetic field variations were studied by considering the parameter delta H which indicated H(observed) minus H(model), where H = (X squared + Y squared) (1/2) where X, Y, and Z are the components actually observed. Quiet time base values for 5 deg longitude belts were estimated. After subtracting these from the observed values, the residual delta H (dawn) and delta H (dusk) were studied for the two major storms. It was noticed that the dusk values attained larger (negative) values for a longer time, than the dawn value. Some changes in delta Y and delta Z were also noticed, indicating possibilities of either meridional currents and/or noncoincidence of the central plane of the ring current with the equatorial plane of the Earth. Other details are described.

Dejesusparada, N.↗
NASA NTRS1981

A synoptic analysis of the first AVE-SESAME '79 period

Key features of a severe convection observed during April 10-11, 1979 as part of the Atmospheric Variability Experiment-Severe Environmental Storms and Mesoscale Experiment (AVE-SESAME) are examined. Three-hourly rawinsonde readings from 23 stations were taken, and vertical motion and divergence parameters are considered. The data were converted into a 127 km grid at the surface, and at 50 mb intervals from 900 mb to 100 mb by an objective analysis scheme, while a kinematic method was used to compute vertical motion. A weak upper tropospheric short wave trough was found to propagate from New Mexico into the Texas panhandle, while a jet maximum propagated eastward. The development of a strong wind maximum over Oklahoma and Kansas was associated with a rapid increase in upper-level divergence and the development of a small-scale pressure perturbation in the Texas panhandle, as well as a low-level jet and convergence, which led to rapid changes over the Red River Valley, where stability was decreased.

Moore, J. T.↗
NASA NTRS1982

System albedo as sensed by satellites - Its definition and variability

System albedo, an important climatological and environmental parameter, is considered. Some of the problems and assumptions involved in evaluating albedo from satellite data are discussed. Clear-sky and cloud albedos over the United Kingdom and parts of northwest Europe are treated. Consideration is given to the spectral, temporal, and spatial variations and the effect of averaging. The implications of these results for those using and archiving albedo values and for future monitoring of system albedo are discussed. Normalization is of especial importance since this correction alters many albedo values. The pronounced difference in spectral albedo of the two visible channels reemphasizes the problem of attempting to calculate integrated albedo values from meteorological satellite data. The assumption of isotropic reflection is seen to be invalid, hindering the computation of accurate albedo values.

Hughes, N. A.↗
NASA NTRS1982

The heating of dust in the broad-line regions of active galaxies and quasars

The present investigation is concerned with the relevant energy sources which heat (and, in many cases, destroy) the dust grains in the emission-line clouds (ELCs) that give rise to the broad-line emission seen in active extragalactic objects. The heating rates from the external radiation field, trapped line radiation, and the diffuse bound-free continua are compared. The relevant grain parameters are considered, taking into account the composition, size, and emission and absorption cross sections. Three distinct regions of an ELC are identified, including the cloud face, the extended ionized zone, and the neutral zone. The thermal emission of the dust in each of these regions is shown to be different. An upper limit to the heating is provided by an LTE model which is discussed.

Rudy, R. J.↗