Search NASA⌕ Search

SEARCH · Search NASA

Results for “special”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 271 records · Page 15
All sourcesNASA NTRSDOE OSTI
NASA NTRS1992

A decade of discovery: Experiments with the Get Away Special (GAS) canister

The experiments from Booker T. Washington's High School for Engineering Profession designed an experiment for a Shuttle flight. The experiments which was flown on STS-42, were contained in three layers of a Get Away Special canister. The first layer housed the Heterogeneous Flow Experiment, to test the commercial application of space exploration; layer two housed an Artemia Salinas Growth Experiment, a test to determine the success and range of food production in microgravity for longer future missions; and layer three, reserved for the computer and monitoring equipment. What was learned from these experiments; and more importantly, what impact they had on education on a broader scale is the subject of this article.

Brienzo, Robert↗
NASA NTRS1992

A payload to evaluate photodiodes for the detection of soft and hard x rays in a space environment using a Get Away Special

We propose to use the Get Away Special (GAS) facility to evaluate P-intrinsic-N (PIN) detectors and avalanche photodiodes (APD's) for the detection of both solar and nonsolar soft and hard x rays. We would like to fly both types of silicon detectors for the direct detection of the x ray photons in the energy range from 1 to 30 keV with an energy resolution of about 1 keV. We would also like to use both types of photodiodes viewing CsI(Tl) scintillators to extend the energy range up to 1 MeV with -6 percent resolution at 660 keV. Solar flares would be detected with this instrumentation during periods of solar pointing providing high energy resolution spectra with high time resolution. Similar data would be obtained in the scanning mode on nonsolar transient and steady x ray sources with the same instrumentation. A commandable door over the detectors would be required to allow measurements to be made as low as 1 keV.

Desai, Upendra D.↗
NASA NTRS1992

The unique challenge of managing an undergraduate Get-Away-Special experiment

A group of Bringham Young University (BYU) undergraduate students has undertaken an experiment to design and build a normal incidence soft x ray robotics telescope for solar observations. The design phase of this, GOLDHELOX project, has now been completed and final construction and modifications are in progress. The design and manufacture of the payload is under the direction of team leaders and a system's integrator. A goal of this project is educating and furnishing experiences in space engineering and physics for undergraduate students. Our main source of funding is NASA and the BYU Colleges of Physical and Mathematical Sciences and Engineering and Technology. This project is possible because of the NASA Get-Away Special (GAS) program. The only feasible alternative is using an expensive sounding rocket. We estimate the sun tracking and guidance package alone would cost upwards of a million dollars -- at least ten times our entire budget. Because of the GAS program, we simplified the construction, operation, and programming of the instruments with resulting savings in weight, cost, and time spent.

Roming, Peter W. A.↗
NASA NTRS1993

NASA scientific and technical publications: A catalog of special publications, reference publications, conference publications, and technical papers, 1991-1992

This catalog lists 458 citations of all NASA Special Publications, NASA Reference Publications, NASA Conference Publications, and NASA Technical Papers that were entered into the NASA Scientific and Technical Information database during accession year 1991 through 1992. The entries are grouped by subject category. Indexes of subject terms, personal authors, and NASA report numbers are provided.

Source record↗
NASA NTRS1993

Report of the Meteoroid and Debris Special Investigation Group

The LDEF Meteoroid and Debris Special Investigation Group (hereafter M&D SIG) was formed to maximize the data harvest from LDEF by permitting the characterization of the meteoroid and space debris impact record of the entire satellite. Thus, our work is complementary to that of the various M&D PI's, all of whom are members of the SIG. This presentation will summarize recent results and discussions concerning five critical SIG goals: (1) classification of impactors based upon composition of residues, (2) small impact (microimpact) features, (3) impact cratering and penetration data to derive projectile sizes and masses, (4) particulate flux estimates in low-Earth orbit, and (5) the LDEF Meteoroid and Debris database.

Zolensky, Michael E.↗
NASA NTRS1993

Continued investigation of LDEF's structural frame and thermal blankets by the Meteoroid and Debris Special Investigation Group

This report focuses on the data acquired by detailed examination of LDEF intercostals, 68 of which are now in possession of the Meteoroid and Debris Special Investigation Group (M&D SIG) at JSC. In addition, limited data will be presented for several small sections from the A0178 thermal control blankets that were examined/counted prior to being shipped to Principal Investigators (PI's) for scientific study. The data presented here are limited to measurements of crater and penetration-hole diameters and their frequency of occurrence which permits, yet also constrains, more model-dependent, interpretative efforts. Such efforts will focus on the conversion of crater and penetration-hole sizes to projectile diameters (and masses), on absolute particle fluxes, and on the distribution of particle-encounter velocities. These are all complex issues that presently cannot be pursued without making various assumptions which relate, in part, to crater-scaling relationships, and to assumed trajectories of natural and man-made particle populations in LEO that control the initial impact conditions.

See, Thomas H.↗
NASA NTRS1993

Overview of the Systems Special Investigation Group investigation

The Long Duration Exposure Facility (LDEF) carried a remarkable variety of electrical, mechanical, thermal, and optical systems, subsystems, and components. Nineteen of the fifty-seven experiments flown on LDEF contained functional systems that were active on-orbit. Almost all of the other experiments possessed at least a few specific components of interest to the Systems Special Investigation Group (Systems SIG), such as adhesives, seals, fasteners, optical components, and thermal blankets. Almost all top level functional testing of the active LDEF and experiment systems has been completed. Failure analysis of both LDEF hardware and individual experiments that failed to perform as designed has also been completed. Testing of system components and experimenter hardware of interest to the Systems SIG is ongoing. All available testing and analysis results were collected and integrated by the Systems SIG. An overview of our findings is provided. An LDEF Optical Experiment Database containing information for all 29 optical related experiments is also discussed.

Mason, James B.↗
NASA NTRS1993

Comparison of special sensor microwave imager vector wind stress with model-derived and subjective products for the tropical Pacific

An assessment of a new source of vector wind stress data relative to existing analyses of the surface wind field is presented. The large-scale variability of vector wind stress generated by Atlas et al. (1991) and based on the special sensor microwave imager (SSM/I) remotely sensed observations of surface wind speed is compared with five operational and subjectively analyzed wind products across the tropical Pacific basin for the first year of SSM/I, July 1987 through June 1988. The spatial and temporal variability of the zonal component, meridional component, and curl of the wind stress are examined relative to their future use in wind-driven ocean model studies of tropical Pacific Ocean circulation.

Busalacchi, Antonio J.↗
NASA NTRS1993

An analysis of errors in special sensor microwave imager evaporation estimates over the global oceans

The method proposed by Liu (1984) is used to estimate monthly averaged evaporation over the global oceans from 1 yr of special sensor microwave imager (SDSM/I) data. Intercomparisons involving SSM/I and in situ data are made over a wide range of oceanic conditions during August 1987 and February 1988 to determine the source of errors in the evaporation estimates. The most significant spatially coherent evaporation errors are found to come from estimates of near-surface specific humidity, q. Systematic discrepancies of over 2 g/kg are found in the tropics, as well as in the middle and high latitudes. The q errors are partitioned into contributions from the parameterization of q in terms of the columnar water vapor, i.e., the Liu q/W relationship, and from the retrieval algorithm for W. The effects of W retrieval errors are found to be smaller over most of the global oceans and due primarily to the implicitly assumed vertical structures of temperature and specific humidity on which the physically based SSM/I retrievals of W are based.

Esbensen, S. K.↗
NASA NTRS1992

Comparison of wind speed measurements over the oceans with the Special Sensor Microwave/Imager and the Geosat altimeter

In order to compare wind speed estimates from the Geosat altimeter and the Special Sensor Microwave/Imager (SSM/I), 25 colocated passes, within 2 hours of each other, were selected and the SSM/I estimates of wind speed and atmospheric parameters extracted along the Geosat track. Both instruments and their algorithms are described. A statistical comparison of wind speed estimates is presented and the effects of the atmospheric parameters from Geosat are analyzed. Quasi-simultaneous measurements by Geosat and SSM/I, along a Geosat track in the North-East Pacific, are also presented.

Mognard, Nelly M.↗
NASA NTRS1993

Validation of Special Sensor Microwave Imager monthly-mean wind speed from July 1987 to December 1989

Since July 1987, the Remote Sensing Systems (Santa Rosa, California) routinely computes from first principles the wind speed from Special Sensor Microwave Imager (SSM/I) measurements of the intensity of microwave radiation emitted at the ocean surface. The accuracy of monthly-mean SSM/I wind speeds is determined by comparisons with moored-buoy wind measurements, which were recorded by four different institutions at 44 sites in the Atlantic and Pacific Oceans during July 1987 to December 1989. All results for 1988 were virtually identical with 1989. The range of monthly mean moored-buoy wind speeds was 2-10 m/s. The rms difference of 697 monthly-mean matchups of the composite 1988 and 1989 data set was 1.2 m/s. The rms differences were smaller in the equatorial zone and higher in middle latitudes, in accord with the monthly standard deviation. At middle latitudes, the time series of rms differences displayed an annual cycle. In the equatorial zone, the agreement between SSM/I and in situ data was better in regions with a lesser amount of clouds, and vice versa. For SSM/I monthly standard deviations of 1-2, 2-3, and 3-4 m/s, the average absolute values of the monthly-mean difference between SSM/I and moored-buoy wind speeds were 0.6, 0.9, and 1.4 m/s, respectively.

Halpern, David↗
NASA NTRS1993

Satellite observations of a polar low over the Norwegian Sea by Special Sensor Microwave Imager, Geosat, and TIROS-N Operational Vertical Sounder

Many polar lows are generated at the boundary between sea ice and the ocean, in regions of large temperature gradients, where in situ observations are rare or nonexistent. Since satellite observations are frequent in high-latitude regions, they can be used to detect polar lows and track their propagation and evolution. The Special Sensor Microwave/Imager (SSM/I) providing estimates of surface wind speed, integrated cloud liquid water content, water vapor content, and precipitation size ice-scattering signal over the ocean; the Geosat radar altimeter measuring surface wind speed and significant wave height; and the TIROS-N Operational Vertical Sounder (TOVS) allowing the determination of temperature and humidity profiles in the atmosphere have been used in synergy for a specific case which occurred in the Norwegian Sea on January, 23-24 1988. All three instruments show sharp atmospheric gradients associated with the propagation of this low across the ocean, which permit the detection of the polar low at a very early stage and tracking it during its development, propagation, and decay. The wind speed gradients are measured with good qualitative agreement between the altimeter and SSM/I. TOVS retrieved fields prior to the formation of the low confirm the presence of an upper level trough, while during the mature phase baroclinicity can be observed in the 1000-500 hPa geopotential thicknesses.

Claud, Chantal↗
NASA NTRS1928

Special Propeller Protractor

A special protractor was designed and built with a view towards supplying a simple, inexpensive, practical, portable instrument for making measurements to detect propeller warpage under practically all conditions, without the use of auxiliary equipment, and without having to remove the propeller from the airplane. A detailed description is given of the protractor. Techniques for measuring are described. Directions are given on how to use the protractor to set detachable blade-type propellers on an airplane.

Heim, A M↗
NASA NTRS1938

Interference of Wing and Fuselage from Tests of 17 Combinations in the NACA Variable-density Tunnel Combination with Special Junctures

As part of the wing-fuselage interference program in progress in the NACA variable-density wind tunnel, a method of eliminating the interference bubble associated with critical mid wing combinations was investigated. The interference bubble of the critical mid wing combination was shown to respond to modification at the nose of the juncture and to be entirely suppressed with little or no adverse effect on the high-speed drag by special leading edge fillets.

Sherman, Albert↗
NASA NTRS1953

Estimation of Hydrodynamic Impact Loads and Pressure Distributions on Bodies Approximating Elliptical Cylinders with Special Reference to Water Landings of Helicopters

An approximate method for computing water loads and pressure distributions on lightly loaded elliptical cylinders during oblique water impacts is presented. The method is of special interest for the case of emergency water landings of helicopters. This method makes use of theory developed and checked for landing impacts of seaplanes having bottom cross sections of V and scalloped contours. An illustrative example is given to show typical results obtained from the use of the proposed method of computation. The accuracy of the approximate method was evaluated through comparison with limited experimental data for two-dimensional drops of a rigid circular cylinder at a trim of 0 degrees and a flight -path angle of 90 degrees. The applicability of the proposed formulas to the design of rigid hulls is indicated by the rough agreement obtained between the computed and experimental results. A detailed computational procedure is included as an appendix.

Schnitzer, Emanuel↗
NASA NTRS1951

A Specially Constructed Metallograph for Use at Elevated Temperatures

A Metallographic microscope was developed with provision for heating a specimen to 1800 F in protective atmospheres, that is, vacuum or gas. A special objective was constructed of reflecting elements with an unusually long working distance (7/16 in.) and a high numerical aperture (0.5). Changes in specimen microstructure were observed and recorded on 35-millimeter motion-picture film. The resulting pictures were projected as motion pictures and individual frames were cut and enlargements made for close observation. Structural changes upon heating a 0.35-percent annealed carbon steel and a 5-percent tin phosphor bronze specimen were observed and recorded. Newly formed microstructure were revealed by selective vacuum etching and specimen relief resulting from recrystallization and varying grain orientation.

INSTRUMENTS, LABORATORY↗
NASA NTRS1921

Properties of Special Types of Radiators

This report discusses the general performance characteristics of three special classes of radiators: those with flat plate water tubes, fin and tube types, and types that whistle in an air stream. Curves and tables show the performance of representative radiators of each class and compare the flat plate and whistling types. Empirical equations are given for estimating the performance of flat plate radiators of various dimensions. This report also contains a brief discussion, with curves, showing the effect of yawing on the properties of a radiator.

Parsons, S R↗
NASA NTRS1938

The influence of lateral stability on disturbed motions of an airplane with special reference to the motions produced by gusts

Distributed lateral motions have been calculated for a hypothetical small airplane with various modifications of fin area and dihedral setting. Special combinations of disturbing factors to simulate gusts are considered and the influence of lateral stability on the motions is discussed. Fin area and wing dihedral were found to be of primary importance in side gusts. It was found that the rolling action of the wing with as much as 5 degrees dihedral was distinctly unfavorable, especially when the weathercock stability was small. It is pointed out that the greatest susceptibility to lateral disturbances lies in the inherent damping and coupling moments developed by the wing.

Jones, Robert T↗