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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 1,081 records · Page 60
All sourcesNASA NTRSDOE OSTI
NASA NTRS1985

Surface-Streamline Flow Visualization

Matrix of ink dots covers matte surface of polyester drafting film. Film placed against wind-tunnel wall. Layer of methyl salicylate (oil of wintergreen) sprayed over dotted area. Ink dot streaklines show several characteristics of flow, including primary saddle point of separations, primary horseshoe vortex and smaller vortex at cylinder/ endwall junction. Surface streamline flow visualization technique suitable for use in low-speed windtunnels or other low-speed gas flows.

Langston, L.↗
NASA NTRS1985

Degreaser Reduces Solvent Loss

Escape of solvent minimized by second cooling coil. Degreaser suppresses solvent-vapor loss through parts-basket dragout and air drafts. Within C02 blanket, convection repeatedly exposes C02/solvent mixture to cold spot created by C02 coil. Solvent vapor condenses, then runs down via through to cold tank. This small expenditure of C02 minimizes health and environmental hazards.

Du Fresne, E. R.↗
NASA NTRS1984

Development of a VOR/DME model for an advanced concepts simulator

The report presents a definition of a VOR/DME, airborne and ground systems simulation model. This description was drafted in response to a need in the creation of an advanced concepts simulation in which flight station design for the 1980 era can be postulated and examined. The simulation model described herein provides a reasonable representation of VOR/DME station in the continental United States including area coverage by type and noise errors. The detail in which the model has been cast provides the interested researcher with a moderate fidelity level simulator tool for conducting research and evaluation of navigator algorithms. Assumptions made within the development are listed and place certain responsibilities (data bases, communication with other simulation modules, uniform round earth, etc.) upon the researcher.

Steinmetz, G. G.↗
NASA NTRS1984

Translators between CADD and section 5 of the ANSI Y14.26M standard

The American National Standard, Engineering Drawing and Related Documentation Practices, Digital Representation for Communication of Product Definition Data (ANSI Y14.26M-1981) comprises an introduction, three sections corresponding to IGES (Initial Graphics Exchange Specification) Version 1.0, and Section 5, a constructive, relational, language-based representation for geometric and topological entities. This presentation discusses the design and development of two-way translators between Section 5 (herein, ANSI5) and CADD (Computer-Aided Design Drafting).

Emnett, R. F.↗
NASA NTRS1984

Using a commercial CAD system for simultaneous input to theoretical aerodynamic programs and wind-tunnel model construction

The Computer Aided Design (CAD) system's common geometry database was used to generate input for theoretical programs and numerically controlled (NC) tool paths for wind tunnel part fabrication. This eliminates the duplication of work in generating separate geometry databases for each type of analysis. Another advantage is that it reduces the uncertainty due to geometric differences when comparing theoretical aerodynamic data with wind tunnel data. The system was adapted to aerodynamic research by developing programs written in Design Analysis Language (DAL). These programs reduced the amount of time required to construct complex geometries and to generate input for theoretical programs. Certain shortcomings of the Design, Drafting, and Manufacturing (DDM) software limited the effectiveness of these programs and some of the Calma NC software. The complexity of aircraft configurations suggests that more types of surface and curve geometry should be added to the system. Some of these shortcomings may be eliminated as improved versions of DDM are made available.

Enomoto, F.↗
NASA NTRS1984

Control Data ICEM: A vendors IPAD-like system

The IPAD program's goal which was to integrate aerospace applications used in support of the engineering design process is discussed. It is still the key goal, and has evolved into a design centered around the use of data base management, networking, and global user executive technology. An integrated CAD/CAM system modeled in part after the IPAD program and containing elements of the program's goals was developed. The integrated computer aided engineering and manufacturing (ICEM) program started with the acquisition of AD-2000 and Synthavision. The AD-2000 has evolved to a production geometry creation and drafting system which is called CD/2000. Synthavision has grown to be a full scale 3-dimensional modeling system, the ICEM Modeler.

Feldman, H. D.↗
NASA NTRS1984

The ESA activities on future launchers

A future launcher development scenario depends on many assumptions, such as the impetus provided by the probability of future missions, and the political willingness of member states to undertake future developments. Because of the long timescale implied by a coherent launcher development, a step-wise approach within an overall future launcher development plan appears essential. The definition of development steps allows the launcher developments to be adapted to the driving external forces, so that no possible opportunity to Europe in the space launch business is missed out because of improper planning on the absence of a long term goal. The launcher senario, to be presented in 1985, forms part of Europe's overall STS plan for the future. This overall STS plan is one product of the complete STS LTPP, a first draft of which should exist by 1985, and which will be updated regularly to take into account the changing political and economic perspectives.

Pfeffer, H.↗
NASA NTRS1984

Space Station Power System

The strategies, reasoning, and planning guidelines used in the development of the United States Space Station Program are outlined. The power required to support Space Station missions and housekeeping loads is a key driver in overall Space Station design. conversely, Space Station requirements drive the power technology. Various power system technology options are discussed. The mission analysis studies resulting in the required Space Station capabilities are also discussed. An example of Space Station functions and a concept to provide them is presented. The weight, area, payload and altitude requirements on draft and mass requirements are described with a summary and status of key power systems technology requirements and issues.

Baraona, C. R.↗
NASA NTRS1985

Extended atmospheres of outer planet satellites and comets

The lifetimes of hydrogen atoms in the environment of Saturn's magnetosphere can be expected to be quite long (approx. 10 to the 8th power s). Preliminary testing of a model of the Titan hydrogen torus for these long-lived orbits was begun. A draft of the paper describing the analysis of Pioneer Venus observations of Comet P/Encke was completed. Plans to analyze Comet P/Halley data, as well as the development of models for cometary carbon and oxygen, are also discussed.

Smyth, W. H.↗
NASA NTRS1985

Evidence for systematic flows in the transition region around prominences

The solar transition region in the neighborhood of prominences has been studied from observations with the Ultraviolet Spectrometer and Polarimeter of NASA's Solar Maximum Mission satellite. Dopplergrams from observations of the transition-region lines C IV 1548 A and Si IV 1393 A, which are formed at about 100,000 K, give velocity amplitudes typically in the range + or - 15 km/s. Prominences are found to be located very close to dividing lines between areas of up- and down-drafts in the transition-region. The observed pattern suggests that the 100,000 K gas flows take place within arcades of magnetic loops, which most likely are part of the supporting magnetic structure for the prominence matter. An additional band of blue-ward Doppler shifts is frequently seen close to quiescent prominences. This may be the source of outward flowing matter along the helmet streamers above filament channels.

Engvold, O.↗
NASA NTRS1985

Structure and evolution of a severe squall line over Oklahoma

The structure of a severe squall line that developed in Oklahoma on May 2, 1979, is presented during its growth and part of its mature period. The line was analyzed using radar, satellite, sounding, and surface data for examining, in particular, the cell propagation mechanisms, the three-dimensional structure of the squall line and individual cells during the mature period, the mass and moisture fluxes, and precipitation efficiency. Comparison of the 1979 Oklahoma squall line with other documented squall lines indicates less well organized down-drafts on the rear side at low levels to midlevels, and an absence of low level to midlevel inflow on the rear side. The magnitude of mass and moisture fluxes was comparable to previous squall line cases. At one point, the motion of the individual cells, initially associated with a synoptic scale cold front, takes a sharp rightward turn. The mechanism of the motion turn is explained in terms of conditions created by a combination of wind shear and moisture convergence and lifting.

Heymsfield, G. M.↗
NASA NTRS1986

Fairness of channel access for non-time-critical traffic using the FDDI token ring protocol

The Fiber Distributed Data Interface (FDDI) is an ANSI draft proposed standard for a 100 megabit per second fiber optic token ring. FDDI supports two types of traffic, synchronous and asynchronous. Synchronous traffic is time critical traffic; stations are assigned guaranteed bandwidth to support their synchronous needs. Asynchronous traffic is lower priority and is sent only if time permits. It is proved analytically that the FDDI access protocol provides all stations on the ring with equal access to the channel to transmit asynchronous frames, regardless of the relative sizes of synchronous bandwidth allocations for individual stations. Analytic results are supported with data from simulation runs.

Johnson, M. J.↗
NASA NTRS1986

Investigation of local area networks for an obiting space station

An investigation and test of various equipment was conducted to determine its state of repair and suitability for use in a test-bed computer network (to be used to simulate a space station configuration of computers for control and monitoring). A research study was also made of various network types, including the IEEE network standards: (1) Carrier Sense Multiple Access with Collision Detection. (2) Token Passing Bus (3) Token Passing Ring, and (4) the draft ANSI standard for a High Speed Local Network, CSMA with Collision Avoidance. No firm conclusions are possible at this time as to which would be most suitable. An evaluation of the user interface of a space station database program, FREDSS (Formatted Retrieval and Entry of Data for Space Station, preliminary version), was also conducted and recommendations were made for possible improvements.

Deacetis, L. A.↗
NASA NTRS1986

Coniferous forest classification and inventory using Landsat and digital terrain data

Machine-processing techniques were used in a Forest Classification and Inventory System (FOCIS) procedure to extract and process tonal, textural, and terrain information from registered Landsat multispectral and digital terrain data. Using FOCIS as a basis for stratified sampling, the softwood timber volumes of the Klamath National Forest and Eldorado National Forest were estimated within standard errors of 4.8 and 4.0 percent, respectively. The accuracy of these large-area inventories is comparable to the accuracy yielded by use of conventional timber inventory methods, but, because of automation, the FOCIS inventories are more rapid (9-12 months compared to 2-3 years for conventional manual photointerpretation, map compilation and drafting, field sampling, and data processing) and are less costly.

Franklin, J.↗
NASA NTRS1986

Coordinated observations of X-ray bright BL Lacertae objects

No new International Ultraviolet Explorer (IUE) observations were scheduled. The work on the spectral extraction routine was continued. The computer code was adapted from the RDAF PDP 11/44 computer to a VAX 11/750, in order that it run more quickly. A chapter on ultraviolet observations of blazars for a book celebrating the scientific accomplishment of IUE was written in colloboration. A copy of the final draft is attached.

Urry, C. M.↗
NASA NTRS1987

Closed-Cycle, Frequency-Stable CO2 Laser Technology

These proceedings contain a collection of papers and comments presented at a workshop on technology associated with long-duration closed-cycle operation of frequency-stable, pulsed carbon dioxide lasers. This workshop was held at the NASA Langley Research Center June 10 to 12, 1986. The workshop, jointly sponsored by the National Aeronautics and Space Administration (NASA) and the Royal Signals and Radar Establishment (RSRE), was attended by 63 engineers and scientists from the United States and the United Kingdom. During the 2 1/2 days of the workshop, a number of issues relating to obtaining frequency-stable operation and to the catalytic control of laser gas chemistry were discussed, and specific recommendations concerning future activities were drafted.

Batten, Carmen E.↗
NASA NTRS1987

Proof that timing requirements of the FDDI token ring protocol are satisfied

The fiber distributed data interface (FDDI) is an ANSI draft proposed standard for a 100 Mbit/s fiber-optic token ring. The FDDI timed token access protocol provides dynamic adjustment of the load offered to the ring, with the goal of maintaining a specified token rotation time and of providing a guaranteed upper bound on time between successive arrivals of the token at a station. FDDI also provides automatic recovery when errors occur. The bound on time between successive token arrivals is guaranteed only if the token rotates quickly enough to satisfy timer requirements in each station when all ring resources are functioning properly. Otherwise, recovery would be initiated unnecessarily. The purpose of this paper is to prove that FDDI timing requirements are satisfied, i.e., the token rotates quickly enough to prevent initiation of recovery unless there is failure of a physical resource or unless the network management entity within a station initiates the recovery process.

Johnson, Marjory J.↗
NASA NTRS1988

Development of drive mechanism for an oscillating airfoil

The design and development of an in-draft wind tunnel test section which will be used to study the dynamic stall of airfoils oscillating in pitch is described. The hardware developed comprises a spanned airfoil between schleiren windows, a four bar linkage, flywheels, a drive system and a test section structure.

Sticht, Clifford D.↗