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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 NTRS1990

Project EGRESS: The design of an assured crew return vehicle for the space station

Keeping preliminary studies by NASA in mind, an Assured Crew Return Vehicle (ACRV) was developed. The system allows the escape of one or more crew members from Space Station Freedom in case of emergency. The design of the vehicle addresses propulsion, orbital operations, reentry, landing and recovery, power and communication, and life support. In light of recent modifications in Space Station design, Project EGRESS (Earthbound Guaranteed ReEntry from Space Station) pays particular attention to its impact on Space Station operations, interfaces and docking facilities, and maintenance needs. A water landing, medium lift vehicle was found to best satisfy project goals of simplicity and cost efficiency without sacrificing the safety and reliability requirements. With a single vehicle, one injured crew member could be returned to Earth with minimal pilot involvement. Since the craft is capable of returning up to five crew members, two such permanently docked vehicles would allow full evacuation of the Space Station. The craft could be constructed entirely with available 1990 technology and launched aboard a shuttle orbiter.

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NASA NTRS1991

Variational formulation of hybrid problems for fully 3-D transonic flow with shocks in rotor

Based on previous research, the unified variable domain variational theory of hybrid problems for rotor flow is extended to fully 3-D transonic rotor flow with shocks, unifying and generalizing the direct and inverse problems. Three variational principles (VP) families were established. All unknown boundaries and flow discontinuities (such as shocks, free trailing vortex sheets) are successfully handled via functional variations with variable domain, converting almost all boundary and interface conditions, including the Rankine Hugoniot shock relations, into natural ones. This theory provides a series of novel ways for blade design or modification and a rigorous theoretical basis for finite element applications and also constitutes an important part of the optimal design theory of rotor bladings. Numerical solutions to subsonic flow by finite elements with self-adapting nodes given in Refs., show good agreement with experimental results.

Liu, Gao-Lian↗
NASA NTRS1992

Space Station Furnace Facility Core. Requirements definition and conceptual design study. Volume 2: Technical report. Appendix 6: Technical summary reports

The Space Station Furnace Facility (SSFF) is a modular facility for materials research in the microgravity environment of the Space Station Freedom (SSF). The SSFF is designed for crystal growth and solidification research in the fields of electronic and photonic materials, metals and alloys, and glasses and ceramics and will allow for experimental determination of the role of gravitational forces in the solidification process. The facility will provide a capability for basic scientific research and will evaluate the commercial viability of low-gravity processing of selected technologically important materials. The facility is designed to support a complement of furnace modules as outlined in the Science Capabilities Requirements Document (SCRD). The SSFF is a three rack facility that provides the functions, interfaces, and equipment necessary for the processing of the furnaces and consists of two main parts: the SSFF Core Rack and the two Experiment Racks. The facility is designed to accommodate two experimenter-provided furnace modules housed within the two experiment racks, and is designed to operate these two furnace modules simultaneously. The SCRD specifies a wide range of furnace requirements and serves as the basis for the SSFF conceptual design. SSFF will support automated processing during the man-tended operations and is also designed for crew interface during the permanently manned configuration. The facility is modular in design and facilitates changes as required, so the SSFF is adept to modifications, maintenance, reconfiguration, and technology evolution.

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NASA NTRS1979

DYLOFLEX modifications to FLEXSTAB. Volume 2: User's manual. Volume 3: Programmer's manual

The changes made to the SD and SS program of the FLEXSTAB computer program system which allows it to be interfaced with the DYLOFLEX program system are described. The changes to specific pages in the FLEXSTAB user's manual are presented. The changes to specific pages in the FLEXSTAB programmer's manual are described. The changes were made for compatibility with the DYLOFLEX and were made in the 2.01 FLEXSTAB SD and SS program.

Dauria, P.↗
NASA NTRS2016

A Modified Edge Crack Torsion Test for Measurement of Mode III Fracture Toughness of Laminated Tape Composites

Modifications to the edge crack torsion (ECT) test are studied to improve the reliability of this test for measuring the mode-III fracture toughness, G (sub IIIc), of laminated tape fiber-reinforced polymeric (FRP) composites. First, the data reduction methods currently used in the ECT test are evaluated and deficiencies in their accuracy are discussed. An alternative data reduction technique, which uses a polynomial form to represent ECT specimen compliance solution, is evaluated and compared to FEA (finite element analysis) results. Second, seven batches of ECT specimens are tested, each batch containing specimens with a preimplanted midplane edge delamination and midplane plies with orientations of plus theta divided by minus theta, with theta ranging from 0 degrees to 90 degrees in 15-degree increments. Tests on these specimens show that intralaminar cracking occurs in specimens from all batches except for which theta = 15 degrees and 30 degrees. Tests on specimens of these two batches are shown to result in mode-III delamination growth at the intended ply interface. The findings from this study are encouraging steps towards the use of the ECT test as a standardized method for measuring G (sub IIIc), although further modification to the data reduction method is required to make it suitable for use as part of a standardized test method.

Czabaj, Michael W.↗
NASA NTRS1973

Report to the administrator by the NASA Aerospace Safety Advisory Panel on the Skylab program. Volume 1: Summary report

Contractor and NASA technical management for the development and manufacture of the Skylab modules is reviewed with emphasis on the following management controls: configuration and interface management; vendor control; and quality control of workmanship. A review of the modified two-stage Saturn V launch vehicle which focused on modifications to accommodate the Skylab payload; resolution of prior flight anomalies; and changes in personnel and management systems is presented along with an evaluation of the possible age-life and storage problems for the Saturn 1-B launch vehicle. The NASA program management's visibility and control of contractor operations, systems engineering and integration, the review process for the evaluation of design and flight hardware, and the planning process for mission operations are investigated. It is concluded that the technical management system for development and fabrication of the modules, spacecraft, and launch vehicles, the process of design and hardware acceptance reviews, and the risk assessment activities are satisfactory. It is indicated that checkout activity, integrated testing, and preparations for and execution of mission operation require management attention.

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NASA NTRS1976

Payload/orbiter contamination control requirement study: Spacelab configuration contamination study

The assessment of the Spacelab carrier induced contaminant environment was continued, and the ability of Spacelab to meet established contamination control criteria for the space transportation system program was determined. The primary areas considered included: (1) updating, refining, and improving the Spacelab contamination computer model and contamination analysis methodology, (2) establishing the resulting adjusted induced environment predictions for comparison with the applicable criteria, (3) determining the Spacelab design and operational requirements necessary to meet the criteria, (4) conducting mission feasibility analyses of the combined Spacelab/Orbiter contaminant environment for specific proposed mission and payload mixes, and (5) establishing a preliminary Spacelab mission support plan as well as model interface requirements; A summary of those activities conducted to date with respect to the modelling, analysis, and predictions of the induced environment, including any modifications in approach or methodology utilized in the contamination assessment of the Spacelab carrier, was presented.

Bareiss, L. E.↗
NASA NTRS1985

Dendritic solidification. I - Analysis of current theories and models. II - A model for dendritic growth under an imposed thermal gradient

A critical review of the present dendritic growth theories and models is presented. Mathematically rigorous solutions to dendritic growth are found to rely on an ad hoc assumption that dendrites grow at the maximum possible growth rate. This hypothesis is found to be in error and is replaced by stability criteria which consider the conditions under which a dendrite tip advances in a stable fashion in a liquid. The important elements of a satisfactory model for dendritic solidification are summarized and a theoretically consistent model for dendritic growth under an imposed thermal gradient is proposed and described. The model is based on the modification of an analysis due to Burden and Hunt (1974) and predicts correctly in all respects, the transition from a dendritic to a planar interface at both very low and very large growth rates.

Laxmanan, V.↗
NASA NTRS1987

Man-machine interface for the control of a lunar transport machine

A proposed first generation human interface control panel is described which will be used to control SKITTER, a three-legged lunar walking machine. Under development at Georgia Tech, SKITTER will be a multi-purpose, un-manned vehicle capable of preparing a site for the proposed lunar base in advance of the arrival of men. This walking machine will be able to accept modular special purpose tools, such as a crane, a core sampling drill, and a digging device, among others. The project was concerned with the design of a human interface which could be used, from earth, to control the movements of SKITTER on the lunar surface. Preliminary inquiries were also made into necessary modifications required to adapt the panel to both a shirt-sleeve lunar environment and to a mobile unit which could be used by a man in a space suit at a lunar work site.

Ashley, Richard↗
NASA NTRS1990

Multi-processing on supercomputers for computational aerodynamics

The MIMD concept is applied, through multitasking, with relatively minor modifications to an existing code for a single processor. This approach maps the available memory to multiple processors, exploiting the C-FORTRAN-Unix interface. An existing single processor algorithm is mapped without the need for developing a new algorithm. The procedure of designing a code utilizing this approach is automated with the Unix stream editor. A Multiple Processor Multiple Grid (MPMG) code is developed as a demonstration of this approach. This code solves the three-dimensional, Reynolds-averaged, thin-layer and slender-layer Navier-Stokes equations with an implicit, approximately factored and diagonalized method. This solver is applied to a generic, oblique-wing aircraft problem on a four-processor computer using one process for data management and nonparallel computations and three processes for pseudotime advance on three different grid systems.

Yarrow, Maurice↗
NASA NTRS1991

Multiprocessing on supercomputers for computational aerodynamics

Little use is made of multiple processors available on current supercomputers (computers with a theoretical peak performance capability equal to 100 MFLOPS or more) to improve turnaround time in computational aerodynamics. The productivity of a computer user is directly related to this turnaround time. In a time-sharing environment, such improvement in this speed is achieved when multiple processors are used efficiently to execute an algorithm. The concept of multiple instructions and multiple data (MIMD) is applied through multitasking via a strategy that requires relatively minor modifications to an existing code for a single processor. This approach maps the available memory to multiple processors, exploiting the C-Fortran-Unix interface. The existing code is mapped without the need for developing a new algorithm. The procedure for building a code utilizing this approach is automated with the Unix stream editor.

Yarrow, Maurice↗
NASA NTRS1991

High performance computing system for flight simulation at NASA Langley

The computer architecture and components used in the NASA Langley Advanced Real-Time Simulation System (ARTSS) are briefly described and illustrated with diagrams and graphs. Particular attention is given to the advanced Convex C220 processing units, the UNIX-based operating system, the software interface to the fiber-optic-linked Computer Automated Measurement and Control system, configuration-management and real-time supervisor software, ARTSS hardware modifications, and the current implementation status. Simulation applications considered include the Transport Systems Research Vehicle, the Differential Maneuvering Simulator, the General Aviation Simulator, and the Visual Motion Simulator.

Cleveland, Jeff I., II↗
NASA NTRS2008

Platform Precision Autopilot Overview and Flight Test Results

The Platform Precision Autopilot is an instrument landing system interfaced autopilot system, developed to enable an aircraft to repeatedly fly nearly the same trajectory hours, days, or weeks later. The Platform Precision Autopilot uses a novel design to interface with a NASA Gulfstream III jet by imitating the output of an instrument landing system approach. This technique minimizes, as much as possible, modifications to the baseline Gulfstream III jet and retains the safety features of the aircraft autopilot. The Platform Precision Autopilot requirement is to fly within a 5-m (16.4-ft) radius tube for distances to 200 km (108 nmi) in the presence of light turbulence for at least 90 percent of the time. This capability allows precise repeat-pass interferometry for the Uninhabited Aerial Vehicle Synthetic Aperture Radar program, whose primary objective is to develop a miniaturized, polarimetric, L-band synthetic aperture radar. Precise navigation is achieved using an accurate differential global positioning system developed by the Jet Propulsion Laboratory. Flight-testing has demonstrated the ability of the Platform Precision Autopilot to control the aircraft within the specified tolerance greater than 90 percent of the time in the presence of aircraft system noise and nonlinearities, constant pilot throttle adjustments, and light turbulence.

Lin, V.↗
NASA NTRS2009

Platform Precision Autopilot Overview and Mission Performance

The Platform Precision Autopilot is an instrument landing system-interfaced autopilot system, developed to enable an aircraft to repeatedly fly nearly the same trajectory hours, days, or weeks later. The Platform Precision Autopilot uses a novel design to interface with a NASA Gulfstream III jet by imitating the output of an instrument landing system approach. This technique minimizes, as much as possible, modifications to the baseline Gulfstream III jet and retains the safety features of the aircraft autopilot. The Platform Precision Autopilot requirement is to fly within a 5-m (16.4-ft) radius tube for distances to 200 km (108 nmi) in the presence of light turbulence for at least 90 percent of the time. This capability allows precise repeat-pass interferometry for the Unmanned Aerial Vehicle Synthetic Aperture Radar program, whose primary objective is to develop a miniaturized, polarimetric, L-band synthetic aperture radar. Precise navigation is achieved using an accurate differential global positioning system developed by the Jet Propulsion Laboratory. Flight-testing has demonstrated the ability of the Platform Precision Autopilot to control the aircraft within the specified tolerance greater than 90 percent of the time in the presence of aircraft system noise and nonlinearities, constant pilot throttle adjustments, and light turbulence.

Strovers, Brian K.↗
NASA NTRS2008

JAVA Stereo Display Toolkit

This toolkit provides a common interface for displaying graphical user interface (GUI) components in stereo using either specialized stereo display hardware (e.g., liquid crystal shutter or polarized glasses) or anaglyph display (red/blue glasses) on standard workstation displays. An application using this toolkit will work without modification in either environment, allowing stereo software to reach a wider audience without sacrificing high-quality display on dedicated hardware. The toolkit is written in Java for use with the Swing GUI Toolkit and has cross-platform compatibility. It hooks into the graphics system, allowing any standard Swing component to be displayed in stereo. It uses the OpenGL graphics library to control the stereo hardware and to perform the rendering. It also supports anaglyph and special stereo hardware using the same API (application-program interface), and has the ability to simulate color stereo in anaglyph mode by combining the red band of the left image with the green/blue bands of the right image. This is a low-level toolkit that accomplishes simply the display of components (including the JadeDisplay image display component). It does not include higher-level functions such as disparity adjustment, 3D cursor, or overlays all of which can be built using this toolkit.

Edmonds, Karina↗
NASA NTRS1990

Multiprocessing on supercomputers for computational aerodynamics

Very little use is made of multiple processors available on current supercomputers (computers with a theoretical peak performance capability equal to 100 MFLOPs or more) in computational aerodynamics to significantly improve turnaround time. The productivity of a computer user is directly related to this turnaround time. In a time-sharing environment, the improvement in this speed is achieved when multiple processors are used efficiently to execute an algorithm. The concept of multiple instructions and multiple data (MIMD) through multi-tasking is applied via a strategy which requires relatively minor modifications to an existing code for a single processor. Essentially, this approach maps the available memory to multiple processors, exploiting the C-FORTRAN-Unix interface. The existing single processor code is mapped without the need for developing a new algorithm. The procedure for building a code utilizing this approach is automated with the Unix stream editor. As a demonstration of this approach, a Multiple Processor Multiple Grid (MPMG) code is developed. It is capable of using nine processors, and can be easily extended to a larger number of processors. This code solves the three-dimensional, Reynolds averaged, thin-layer and slender-layer Navier-Stokes equations with an implicit, approximately factored and diagonalized method. The solver is applied to generic oblique-wing aircraft problem on a four processor Cray-2 computer. A tricubic interpolation scheme is developed to increase the accuracy of coupling of overlapped grids. For the oblique-wing aircraft problem, a speedup of two in elapsed (turnaround) time is observed in a saturated time-sharing environment.

Yarrow, Maurice↗
NASA NTRS1991

Evaluation and Analysis of the ANSI X3T9.5 (FDDI) PMD and Proposed SMF-PMD as Influenced by Various Fiber Link Characteristics

The purpose of this project is to evaluate the operational parameters of the Kennedy Space Center (KSC) fiber optic cable plant. The evaluation is based on the Fiber Distributed Data Interface (FDDI) Physical Medium Dependent (PMD) and Single Mode Fiber (SMF) PMD standards. From the KSC fiber profile, it would be necessary to develop the modifications needed in existing FDDI PMD and proposed SMF-PMD standards to provide for FDDI implementation and operation at KSC. This analysis should examine the major factors that influence the operating conditions of the KSC fiber plant. These factors would include, but are not limited to the number and type of connectors, attenuation and dispersion characteristics of the fiber, non-standard fiber sizes, modal bandwidth, and many other relevant or significant fiber plant characteristics that effect FDDI characteristics. This analysis is needed to gain a better understanding of overall impact that each of these factors have on FDDI performance at KSC.

Wernicki, M. Chris↗
NASA NTRS1997

MFLOP to GFLOP: The Impact on High Fidelity Based Computational Aeroelasticity

Aeroelasticity which involves strong coupling of fluids, structures and controls is an important element in designing an aircraft. Computational aeroelasticity using low fidelity methods such as the linear aerodynamic flow equations coupled with the modal structural equations are well advanced. Though these low fidelity approaches are computationally less intensive, they are not adequate for the analysis of modern aircraft which can experience complex flow/structure interactions. Even at moderate angles of attack supersonic aircraft can experience vortex induced aeroelastic oscillations. Near transonic speeds buffet associated structural oscillations are possible. Aircraft flying in transonic regime may experience a dip in the flutter speed. For accurate aeroelastic computations at these complex fluid/structure interaction situations, high fidelity equations such as the Navier-Stokes for fluids and the finite-elements for structures are needed. Computations using these high fidelity equations require large computational resources both in memory and speed. Current conventional supercomputers have reached their limitations both in memory and speed. As a result, parallel computers have evolved to overco me the limitations of conventional computers. This paper will address the transition that is taking place in computational aeroelasticity from conventional computers to parallel computers. The paper will address special techniques needed to take advantage of the architecture of new parallel computers. Results will be illustrated from computations made on iPSC/860 and IBM SP2 computer by using ENSAERO code that directly couples the Euler/Navier-Stokes flow equations with high resolution finite-element structural equations. Modifications required in both fluids and structural solvers in order to run efficiently on parallel computers will be discussed. Implementation of moving grids and fluid/structural interface on parallel computers will be discussed.

Guruswamy, Guru P.↗