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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 595 records · Page 33
All sourcesNASA NTRSDOE OSTI
NASA NTRS1977

Application of altitude control techniques for low altitude earth satellites

The applications sensors of many low altitude earth satellites designed for recording surface or atmospheric data require near zero orbital eccentricities for maximum usefulness. Coverage patterns and altitude profiles require specified values of orbit semimajor axis. Certain initial combinations of semimajor axis, eccentricity, and argument of perigee can produce a so called 'frozen orbit' and minimum altitude variation which enhances sensor coverage. This paper develops information on frozen orbits and minimum altitude variation for all inclinations, generalizing previous results. In the altitude regions where most of these satellites function (between 200 and 1000 kilometers) strong atmospheric drag effects influence the evolution of the initial orbits. Active orbital maneuver control techniques to correct evolution of orbit parameters while minimizing the frequency of maneuvers are presented. The paper presents the application of theoretical techniques for control of near frozen orbits and expands upon the methods useful for simultaneously targeting several inplane orbital parameters. The applications of these techniques are illustrated by performance results from the Atmosphere Explorer (AE-3 and -5) missions and in preflight maneuver analysis and plans for the Seasat Oceanographic Satellite.

Nickerson, K. G.↗
NASA NTRS1978

Preliminary design package for prototype solar heating system

A summary is given of the preliminary analysis and design activity on solar heating systems. The analysis was made without site specific data other than weather; therefore, the results indicate performance expected under these special conditions. Major items include system candidates, design approaches, trade studies and other special data required to evaluate the preliminary analysis and design. The program calls for the development and delivery of eight prototype solar heating and cooling systems for installation and operational test.

Source record↗
NASA NTRS1978

Preliminary design package for prototype solar heating and cooling systems

A summary is given of the preliminary analysis and design activity on solar heating and cooling systems. The analysis was made without site specific data other than weather; therefore, the results indicate performance expected under these special conditions. Major items include a market analysis, design approaches, trade studies and other special data required to evaluate the preliminary analysis and design. The program calls for the development and delivery of eight prototype solar heating and cooling systems for installation and operational test. Two heating and six heating and cooling units will be delivered for Single Family Residences, Multiple-family Residences and commercial applications.

Source record↗
NASA NTRS1978

Characterization of large 2219 aluminum alloy hand forgings for the space shuttle solid rocket booster

The mechanical properties, including fracture toughness, and stress corrosion properties of four types of 2219-T852 aluminum alloy hand forgings are presented. Weight of the forgings varied between 450 and 3500 lb at the time of heat treatment and dimensions exceeded the maximum covered in existing specifications. The forgings were destructively tested to develop reliable mechanical property data to replace estimates employed in the design of the Space Shuttle Solid Rocket Booster (SRB) and to establish minimum guaranteed properties for structural refinement and for entry into specification revisions. The report summarizes data required from the forgers and from the SRB Structures contractor.

Brennecke, M. W.↗
NASA NTRS1977

General purpose computer program for interacting supersonic configurations. User's manual

The input data required to execute the computer program ISCON are described. The program generates a numerical procedure for the determination of unsteady aerodynamic forces on arbitrarily interacting wings and tails in supersonic flow. A velocity potential gradient method is used. Constant Mach number is assumed throughout the flow field. Lifting surfaces are represented by trapezoidal elements which can be generated automatically by the program. The wake field is represented by rectangular strip elements. The formulation is reviewed as well as input overview and input format. Instruction on how to use ISCON, a sample problem, and the restart feature are discussed. Program size limitations, computer program flow, and error messages are also included along with a description of the SS31 program used to compute the coefficients of surface spline.

Crill, W.↗
NASA NTRS1978

Recent advances in computational techniques

The determination of very precise orbits and geodynamic parameters from laser tracking data requires the continual development and improvement of the software systems and computational techniques. Computational accuracies at the few centimeter level are presently required to match the performance of the present day laser ranging systems and altimeters and in the next few years the accuracies are expected to increase further. The major error sources in orbit determination are briefly discussed and the present and future modeling activities needed to meet the accuracy requirements of the next few years are described.

Smith, D. E.↗
NASA NTRS1979

Dynamic loads analysis system (DYLOFLEX) summary. Volume 1: Engineering formulation

The DYLOFLEX computer program system expands the aeroelastic cycle from that in the FLEXSTAB computer program system to include dynamic loads analyses involving active controls. Two aerodynamic options exist within DYLOFLEX. The analyst can formulate the problem with unsteady aerodynamics calculated using the doublet lattice method or with quasi-steady aerodynamics formulated from either FLEXSTAB or doublet lattice steady state aerodynamics with unsteady effects approximated by indicial lift growth functions. The equations of motion are formulated assuming straight and level flight and small motions. Loads are calculated using the force summation technique. DYLOFLEX consists of nine standalone programs which can be linked with each other by magnetic files used to transmit the required data between programs.

Miller, R. D.↗
NASA NTRS1978

Application of space remote sensing technology to living marine resources in coastal zones

This paper describes a compilation of new Landsat satellite remote sensing techniques for treatment of Coastal Zone Living Marine Resource problems. The techniques have been developed over the past three to five years using optimized digital analysis procedures and evaluated in limited coastal areas of the United States. However, most of the techniques are directly applicable to other areas of the world, particularly in those areas where Landsat satellite data are available. Each technique presented herein has been documented and published separately as a NASA report within the last three years. The data required to substantiate the conclusion that 'significant new space remote sensing techniques are now available for the treatment of Coastal Zone Living Marine Resource problems' are contained within these reports and are referenced herein.

Tilton, E. L., III↗
NASA NTRS1977

50 Mbps hardware development for Shuttle Ku-band communications

The performance of a 5-Mbps coded system developed for Shuttle Ku-band communications is described. The system consists of a rate 1/2, constraint length 7 convolutional encoder-decoder and soft decision symbol synchronizer; the system has been band-limited at the transmitted symbol rate. Five convolutional decoders are operated in parallel to permit operation at the required data rate. It is found that the multiplexed encoder-decoder system does not exhibit any observable coding gain degradation when the channel is limited to the symbol rate at baseband.

Vang, H. A.↗
NASA NTRS1978

X-ray observation of IC 4329 A

X-rays from the extreme type 1 Seyfert galaxy IC 4329 A have been observed with the rotating modulation collimator on board SAS 3. In addition to establishing IC 4329 A as an X-ray source, the SAS 3 data require that the source be extended, that there be at least one other nearby source, or both.

Delvaille, J. P.↗
NASA NTRS1979

Further observational support for the lossy radial diffusion model of the inner Jovian magnetosphere

A mathematical model describing radial diffusion, with violation of the third adiabatic invariant and with local losses, is applied to the Pioneer 10 and 11 observations of omnidirectional integral intensities of electrons with energy exceeding 21 MeV. Local losses outside L = 3 are much stronger than synchrotron losses but weaker than the losses one would expect for strong pitch angle diffusion. If radial diffusion is driven by ionospheric winds, as was suggested by Brice and McDonough (1973), it is found that the theoretical solution which best fits the data requires that the radial diffusion coefficient equals 3 x 10 to the -9th L-cubed/s and the lifetime against local losses is approximately a few million seconds.

Goertz, C. K.↗
NASA NTRS1980

The SEM description of interaction of a transient electromagnetic wave with an object

The singularity expansion method (SEM), proposed as a means for determining and representing the transient surface current density induced on a scatterer by a transient electromagnetic wave is described. The resulting mathematical description of the transient surface current on the object is discussed. The data required to represent the electromagnetic scattering properties of a given object are examined. Experimental methods which were developed for the determination of the SEM description are discussed. The feasibility of characterizing the surface current induced on aircraft flying in proximity to a lightning stroke by way of SEM is examined.

Pearson, L. W.↗
NASA NTRS1980

Operations manual: Vertical Motion Simulator (VMS) S.08

The Ames Research Center Vertical Motion Simulator (VMS) is described in terms useful to the researcher who intends to use it. A description of the VMS and its performance are presented together with the administrative policies governing its operation. The management controls over its use are detailed, including data requirements, user responsibilities, and scheduling procedures. This information is given in a form that should facilitate communication with the NASA operations group during initial simulator use.

Jones, A. D.↗
NASA NTRS1980

A simple method for converting frequency domain aerodynamics to the time domain

A simple, direct procedure was developed for converting frequency domain aerodynamics into indicial aerodynamics. The data required for aerodynamic forces in the frequency domain may be obtained from any available (linear) theory. The method retains flexibility for the analyst and is based upon the particular character of the frequency domain results. An evaluation of the method was made for incompressible, subsonic, and transonic two dimensional flows.

Dowell, E. H.↗
NASA NTRS1980

Remote sensing of the middle atmospheric aerosol

It is shown that current or planned spacecraft measurements could contribute toward the input data required for studies of natural anthropogenic influences on the middle atmosphere and their effects on weather and climate. Emphasis is placed on the solar occultation sounding technique used in the SAGE I experiment on board the Atmospheric Explorer Mission B spacecraft. It is shown that the aerosol and ozone number densities cannot be recovered simultaneously without introducing some formula for the aerosol extinction, or assumptions on the form of the aerosol size distribution.

Fymat, A. L.↗
NASA NTRS1980

The ultraviolet dayglow. I - Far UV emissions of N and N2

Far ultraviolet rocket spectra of N I and N2 dayglow emissions have been analyzed by using AE-E photoelectron spectra, laboratory-measured excitation cross sections, and photochemical models of atomic nitrogen. A self-consistent picture of both optically thick and thin emission features is found by using a model in which the principal production mechanism for N I 1200-A and 1493-A photons is photodissociative excitation of N2. The aeronomic data require that 50-70% of the excited 4 P atoms produced dissociatively have velocities within the Doppler core of the ambient nitrogen atoms, contrary to the expectation that those atoms are produced with large excess kinetic energy. The derived atomic nitrogen density has a maximum density of 2.7 x 10 to the 7th per cu cm at 170 km, a value that is within 40% of that from recent models of odd nitrogen photochemistry.

Meier, R. R.↗
NASA NTRS1982

Numerical Solution for Navier-Stokes Equations

Carefully selected blend of computational techniques solves complete set of equations for viscous, unsteady, hypersonic flow in general curvilinear coordinates. New algorithm has tested computation of axially directed flow about blunt body having shape similar to that of such practical bodies as wide-body aircraft or artillery shells. Method offers significant computational advantages because of conservation-law form of equations and because it reduces amount of metric data required.

Warsi, Z. U. A.↗
NASA NTRS1980

A new look at Togo through the eyes of a SLAR

Imaging of Togo in 1977 with SLAR provided the data required for the production of map controlled radar mosaics at a scale of 1:200,000 with 95 percent of all control points at that scale within + or - 4.0 millimeters of true positions. The moasics served as the base for the generation of a revised geologic map of Togo. Aided by two looks, numerous revisions resulted, not only with the addition of previously unknown structural features, a revision of age relationships, and the refinement of unit boundaries, but also with the repositioning of rock units and the reorientation of major faults.

Dellwig, L. F.↗