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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 325 records · Page 18

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NASA NTRS1991

Liquid booster engine reuse - A recovery system

The paper presents the design of a recovery system for a suborbital payload of an Atlas E rocket. This program utilizes off-the-shelf and previously qualified avionics, flotation, and decelerator systems. A brief history of liquid-engine recoveries is presented first, then the system design utilizing two self-contained structurally-identical pods diametrically mounted to the thrust section is outlined. A mortar-deployed drogue and the main parachute are described, and experimental procedures are considered. Data obtained from one tricluster drop employing a cylindrical test vehicle and helicopter is analyzed, and a satisfactory load balance between the parachutes is observed.

Von Eckroth, Wulf↗

NASA NTRS1989

Stopping computer crimes

Two new books about intrusions and computer viruses remind us that attacks against our computers on networks are the actions of human beings. Cliff Stoll's book about the hacker who spent a year, beginning in Aug. 1986, attempting to use the Lawrence Berkeley Computer as a stepping-stone for access to military secrets is a spy thriller that illustrates the weaknesses of our password systems and the difficulties in compiling evidence against a hacker engaged in espionage. Pamela Kane's book about viruses that attack IBM PC's shows that viruses are the modern version of the old problem of a Trojan horse attack. It discusses the most famous viruses and their countermeasures, and it comes with a floppy disk of utility programs that will disinfect your PC and thwart future attack.

Denning, Peter J.↗

NASA NTRS1992

Lunar Resource Assessment: Strategies for Surface Exploration

Use of the indigenous resources of space to support long-term human presence is an essential element of the settlement of other planetary bodies. We are in a very early stage of understanding exactly how and under what circumstances space resources will become important. The materials and processes to recover them that we now think are critical may not ultimately be the raison d'etre for a resource utilization program. However, the need for strategic thinking proceeds in parallel with efforts to implement such plans and it is not too soon to begin thinking how we could and should use the abundant resources of materials and energy available from the Moon. The following commodities from the Moon are discussed: (1) bulk regolith, for shielding and construction on the lunar surface (ultimately for export to human-tended stations in Earth-Moon space), and (2) oxygen and hydrogen, for propellant and life support.

Spudis, Paul D.↗

NASA NTRS1993

Future directions for LDEF ionizing radiation modeling and assessments

A calculational program utilizing data from radiation dosimetry measurements aboard the Long Duration Exposure Facility (LDEF) satellite to reduce the uncertainties in current models defining the ionizing radiation environment is in progress. Most of the effort to date has been on using LDEF radiation dose measurements to evaluate models defining the geomagnetically trapped radiation, which has provided results applicable to radiation design assessments being performed for Space Station Freedom. Plans for future data comparisons, model evaluations, and assessments using additional LDEF data sets (LET spectra, induced radioactivity, and particle spectra) are discussed.

Armstrong, T. W.↗

NASA NTRS1992

Radii effect on the translation spring constant of force transducer beams

Multi-component strain-gage force transducer design requires the designer to determine the spring constant of the numerous beams or flexures incorporated in the transducer. The classical beam deflection formulae that are used in calculating these spring constants typically assume that the beam has a uniform moment of inertia along the entire beam length. In practice all beams have a radius at the end where the beam interfaces with the shoulder of the transducer, and on short beams in particular this increases the beam spring constant considerably. A Basic computer program utilizing numerical integration is presented to determine this effect.

Scott, C. E.↗

NASA NTRS1992

Interdisciplinary analysis from the spacecraft thermal analyst's viewpoint

Interdisciplinary analyses performed at the Marshall Space Flight Center based on multidiscipline data flows are reviewed. Particular attention is given to global software packages for allowing efficient interdisciplinary data exchange, the use of a number of smaller individual packages, specific software programs utilized by the various interfacing disciplines to perform calculations in terms of interface compatibility, and tasks based on thermal evaluations integral. Recommendations for improvements in the MSFC equipment, software, and organization are proposed.

Humphries, W. R.↗

NASA NTRS1994

Composite-Plate-Buckling Analysis Program

Composite-Plate-Buckling Analysis Program (COMPPAP) helps engineers determine buckling loads of orthotropic or isotropic irregularly shaped plates without need to perform manual calculations and extensive finite-element mathematical modeling. One-element finite-element program utilizing high-order displacement functions to perform plane-stress analysis of general plate followed by buckling calculation based on stresses found in plane-stress solution. High order of displacement functions enables user to obtain results more accurately. Written in ANSI FORTRAN 77. Two machine versions available: (MSC-22428) for computers of IBM PC 386 and higher series and for compatible computers; and UNIX (MSC-22286).

Smith, James P.↗

NASA NTRS1993

The possibilities for mobile and fixed services in the 20/30 GHz frequency bands

With the wide range of services now offered by satellite communications and broadcasting and the increasing trend towards small terminal systems, the traditional distinctions between fixed and mobile services are becoming less important. In the future mobile, portable, and fixed services may well operate side by side in a hybrid manner. This trend is already apparent in Europe where extensive use is being made of the fixed service frequency allocations for broadcasting and for mobile services. Similarly many ostensibly mobile terminals are serving fixed installations. Although the immediate future of mobile satellite communications continues to lie in the L-band frequency allocations, in the longer term the 20/30 GHz frequency allocations, offer the possibility of a new beginning where the advantages of hybrid systems can be included in the overall system designs at the outset. The experience gained using 20/30 GHz within the Olympus Utilization program and the likely demands for future services to highlight the most promising avenues for future system development are addressed.

Hughes, C. D.↗

NASA NTRS1994

Installed F/A-18 inlet flow calculations at 30 degrees angle-of-attack: A comparative study

NASA Lewis is currently engaged in a research effort as a team member of the High Alpha Technology Program (HATP) within NASA. This program utilizes a specially equipped F/A-18, the High Alpha Research Vehicle (HARV), in an ambitious effort to improve the maneuverability of high-performance military aircraft at low subsonic speed, high angle of attack conditions. The overall objective of the Lewis effort is to develop inlet technology that will ensure efficient airflow delivery to the engine during these maneuvers. One part of the Lewis approach utilizes computational fluid dynamics codes to predict the installed performance of inlets for these highly maneuverable aircraft. Full Navier-Stokes (FNS) calculations on the installed F/A-18 inlet at 30 degrees angle of attack, 0 degrees yaw, and a freestream Mach number of 0.2 have been obtained in this study using an algebraic turbulence model with two grids (original and revised). Results obtained with the original grid were used to determine where further grid refinements and additional geometry were needed. In order to account properly for the external effects, the forebody, leading edge extension (LEX), ramp, and wing were included with inlet geometry. In the original grid, the diverter, LEX slot, and leading edge flap were not included due to insufficient geometry definition, but were included in a revised grid. In addition, a thin-layer Navier-Stokes (TLNS) code is used with the revised grid and the numerical results are compared to those obtained with the FNS code. The TLNS code was used to evaluate the effects on the solution using a code with more recent CFD developments such as upwinding with TVD schemes versus central differencing with artificial dissipation. The calculations are compared to a limited amount of available experimental data. The predicted forebody/fuselage surface static pressures compared well with data of all solutions. The predicted trajectory of the vortex generated under the LEX was different for each solution. These discrepancies are attributed to differences in the grid resolution and turbulence modeling. All solutions predict that this vortex is ingested by the inlet. The predicted inlet total pressure recoveries are lower than data and the distortions are higher than data. The results obtained with the revised grid were significantly improved from the original grid results. The original grid results indicated the ingested vortex migrated to the engine face and caused additional distortions to those already present due to secondary flow development. The revised grid results indicate that the ingested vortex is dissipated along the inlet duct inboard wall. The TLNS results indicate the flow at the engine face was much more distorted than the FNS results and is attributed to the pole boundary condition introducing numerical distortions into the flow field.

Smith, C. Frederic↗

NASA NTRS1992

Advanced composites structural concepts and materials technologies for primary aircraft structures. Structural response and failure analysis: ISPAN modules users manual

The ISPAN Program (Interactive Stiffened Panel Analysis) is an interactive design tool that is intended to provide a means of performing simple and self contained preliminary analysis of aircraft primary structures made of composite materials. The program combines a series of modules with the finite element code DIAL as its backbone. Four ISPAN Modules were developed and are documented. These include: (1) flat stiffened panel; (2) curved stiffened panel; (3) flat tubular panel; and (4) curved geodesic panel. Users are instructed to input geometric and material properties, load information and types of analysis (linear, bifurcation buckling, or post-buckling) interactively. The program utilizing this information will generate finite element mesh and perform analysis. The output in the form of summary tables of stress or margins of safety, contour plots of loads or stress, and deflected shape plots may be generalized and used to evaluate specific design.

Hairr, John W.↗

NASA NTRS1989

The Characterization of Technology Transfer as it Occurs at Ames Research Center

This is a preliminary report--more of a progress report following the first series of interviews at the Center as part of the Study on Characterization of NASA Technology Transfer. Its primary purpose is to provide a general description of the various ways in which technology transfer takes place at the Center, even whether or not it is part of the formal Technology Utilization program. To the extent possible, we have illustrated the different means of transfer.

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NASA NTRS1995

Open Loop Simulation

My project is designing a flight control program utilizing 'C' language. It consists of paths made up of fixed radius arcs and straight lines. Arcs will be defined by a center, a radius and turn angle. Straight lines will be defined by an end way point and an inbound course. Way points will be pre-defined such that the location of the end of each leg accurately matches the beginning of the next leg. The simulation paths will closely match paths normally flown by the Transport System Research Vehicle (TSRV), but will necessarily be defined identically in terms of type and number of way points.

Thomas, Tamera L.↗

NASA NTRS1997

A Preliminary Investigation of Hall Thruster Technology

A three-year, NASA/BMDO-sponsored experimental program to conduct performance and plume plasma property measurements on two Russian Stationary Plasma Thrusters (SPTs) has been completed. The program utilized experimental facilitates at the University of Michigan's Plasmadynamics and Electric Propulsion Laboratory (PEPL). The main features of the proposed effort were as follows: We Characterized Hall thruster [and arcjet] performance by measuring ion exhaust velocity with probes at various thruster conditions. Used a variety of probe diagnostics in the thruster plume to measure plasma properties and flow properties including T(sub e) and n(sub e), ion current density and ion energy distribution, and electric fields by mapping plasma potential. Used emission spectroscopy to identify species within the plume and to measure electron temperatures.

Gallimore, Alec D.↗

NASA NTRS1999

Acoustic Treatment Design Scaling Methods: Overview, Results, and Recommendations - Volume 1

Scale model fan rigs that simulate new generation ultra-high-bypass engines at about 1/5-scale are achieving increased importance as development vehicles for the design of low-noise aircraft engines. Testing at small scale allows the tests to be performed in existing anechoic wind tunnels, which provides an accurate simulation of the important effects of aircraft forward motion on the noise generation. The ability to design, build, and test miniaturized acoustic treatment panels on scale model fan rigs representative of the fullscale engine provides not only a cost-savings, but an opportunity to optimize the treatment by allowing tests of different designs. The primary objective of this study was to develop methods that will allow scale model fan rigs to be successfully used as acoustic treatment design tools. The study focuses on finding methods to extend the upper limit of the frequency range of impedance prediction models and acoustic impedance measurement methods for subscale treatment liner designs, and confirm the predictions by correlation with measured data. This phase of the program had as a goal doubling the upper limit of impedance measurement from 6 kHz to 12 kHz. The program utilizes combined analytical and experimental methods to achieve the objectives.

Kraft, R. E.↗

NASA NTRS1999

Improving Scientific Capabilities in Space in the 21st Century: The NASA New Millennium Program

NASA's New Millennium Program (NMP) has been chartered to identify and validate in space emerging, revolutionary technologies that will enable less costly, more capable future science missions. The program utilizes a unique blend of science guidance and industry partnering to ferret out technology solutions to enable science capabilities in space which are presently technically infeasible, or unaffordable. Those technologies which present an unacceptably high risk to future science missions (whether small PI-led or operational) are bundled into technology validation missions. These missions seek to validate the technologies in a manner consistent with their future uses, thus reducing the associated risk to the first user, and obtaining meaningful science data as well. The Space Readiness Coherent Lidar Experiment (SPARCLE) was approved as the second NMP Earth Observing mission (EO2) in October 1997, and assigned to Marshall Space Flight Center for implementation. Leading up to mission confirmation, NMP sponsored a community workshop in March 1996 to draft Level-1 requirements for a doppler wind lidar mission, as well as other space-based lidar missions (such as DIAL). Subsequently, a study group was formed and met twice to make recommendations on how to perform a comparison of coherent and direct detection wind lidars in space. These recommendations have guided the science validation plan for the SPARCLE mission, and will ensure that future users will be able to confidently assess the risk profile of future doppler wind missions utilizing EO2 technologies. The primary risks to be retired are: (1) Maintenance of optical alignments through launch and operations on orbit, and (2) Successful velocity estimation compensation for the Doppler shift due to the platform motion, and due to the earth's rotation. This includes the need to account for all sources of error associated with pointing control and knowledge. The validation objectives are: (1) Demonstrate measurement of tropospheric winds from space using a scanning coherent Doppler lidar technique that scales to meet future research (e.g. ESSP) and operational (e.g. NPOESS) mission requirements. Specifically, produce and validate LOS wind data with single shot accuracy of 1-2 m/s in regions of high signal-to-noise ratio (SNR), and low atmospheric wind turbulence and wind shear, (2) Collect the atmospheric and instrument performance data in various scanning modes necessary to validate and improve instrument performance models that will enable the definition of future missions with greater confidence. Such data include aerosol backscatter data over much of the globe, and high SNR data such as that from surface returns, and (3) Produce a set of raw instrument data with which advanced signal processing techniques can be developed. This objective will permit future missions to better understand how to extract wind information from low backscatter regions of the atmosphere.

Raymond, Carol A.↗

NASA NTRS2001

Large Composite Structures Processing Technologies for Reusable Launch Vehicles

Significant efforts have been devoted to establishing the technology foundation to enable the progression to large scale composite structures fabrication. We are not capable today of fabricating many of the composite structures envisioned for the second generation reusable launch vehicle (RLV). Conventional 'aerospace' manufacturing and processing methodologies (fiber placement, autoclave, tooling) will require substantial investment and lead time to scale-up. Out-of-autoclave process techniques will require aggressive efforts to mature the selected technologies and to scale up. Focused composite processing technology development and demonstration programs utilizing the building block approach are required to enable envisioned second generation RLV large composite structures applications. Government/industry partnerships have demonstrated success in this area and represent best combination of skills and capabilities to achieve this goal.

Clinton, R. G., Jr.↗

NASA NTRS1997

Improved Boundary Conditions for Cell-centered Difference Schemes

Cell-centered finite-volume (CCFV) schemes have certain attractive properties for the solution of the equations governing compressible fluid flow. Among others, they provide a natural vehicle for specifying flux conditions at the boundaries of the physical domain. Unfortunately, they lead to slow convergence for numerical programs utilizing them. In this report a method for investigating and improving the convergence of CCFV schemes is presented, which focuses on the effect of the numerical boundary conditions. The key to the method is the computation of the spectral radius of the iteration matrix of the entire demoralized system of equations, not just of the interior point scheme or the boundary conditions.

VanderWijngaart, Rob F.↗

NASA NTRS1991

Heart Research

James Antaki and a group of researchers from the University of Pittsburgh School of Medicine used many elements of the Technology Utilization Program while looking for a way to visualize and track material points within the heart muscle. What they needed were tiny artificial "eggs" containing copper sulfate solution, small enough (about 2 mm in diameter) that they would not injure the heart, and large enough to be seen in Magnetic Resonance Imaging (MRI) images; they also had to be biocompatible and tough enough to withstand the beating of the muscle. The group could not make nor buy sufficient containers. After reading an article on microspheres in NASA Tech Briefs, and a complete set of reports on microencapsulation from the Jet Propulsion Laboratory (JPL), JPL put Antaki in touch with Dr.Taylor Wang of Vanderbilt University who helped construct the myocardial markers. The research is expected to lead to improved understanding of how the heart works and what takes place when it fails.

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