Select from the following NASA centers to view citations of cutting-edge STI that was recently documented and archived. A link to the STI Order Form is also included with each citation.

	Hypothetical Reentry Thermostructural Performance of Space Shuttle Orbiter With Missing or Eroded Thermal Protection Tiles
	Heat Shielding Characteristics and Thermostructural Performance of a Superalloy Honeycomb Sandwich Thermal Protection System (TPS)
	Energy Management of Manned Boost-Glide Vehicles: A Historical Perspective
	Debonding Stress Concentrations in a Pressurized Lobed Sandwich-Walled Generic Cryogenic Tank
	Back to Top Report Number: NASA/TM-2004-212850; H-2553 Title (Incl. Subtitle): Hypothetical Reentry Thermostructural Performance of Space Shuttle Orbiter With Missing or Eroded Thermal Protection Tiles Publication Date: July 2004 Authorized Users: Publicly available Author: Ko, William L.; Gong, Leslie; Quinn, Robert D. Author Affil.: NASA Dryden Flight Research Center; NASA Dryden Flight Research Center; NASA Dryden Flight Research Center Abstract: This report deals with hypothetical reentry thermostructural performance of the Space Shuttle orbiter with missing or eroded thermal protection system (TPS) tiles. The original STS-5 heating (normal transition at 1100 sec) and the modified STS-5 heating (premature transition at 800 sec) were used as reentry heat inputs. The TPS missing or eroded site is assumed to be located at the center or corner (spar-rib juncture) of the lower surface of wing midspan bay 3. For cases of missing TPS tiles, under the original STS-5 heating, the orbiter can afford to lose only one TPS tile at the center or two TPS tiles at the corner (spar-rib juncture) of the lower surface of wing midspan bay 3. Under modified STS-5 heating, the orbiter cannot afford to lose even one TPS tile at the center or at the corner of the lower surface of wing midspan bay 3. For cases of eroded TPS tiles, the aluminum skin temperature rises relatively slowly with the decreasing thickness of the eroded central or corner TPS tile until most of the TPS tile is eroded away, and then increases exponentially toward the missing tile case. Order: Document ID (CASI): 20040082249 Financial Sponsor: NASA Dryden Flight Research Center Back to Top Report Number: NASA/TP-2004-212024; H-2492 Title (Incl. Subtitle): Heat Shielding Characteristics and Thermostructural Performance of a Superalloy Honeycomb Sandwich Thermal Protection System (TPS) Publication Date: May 2004 Authorized Users: Publicly available Author: Ko, William L. Author Affil.: NASA Dryden Flight Research Center Abstract: Heat-transfer, thermal bending, and mechanical buckling analyses have been performed on a superalloy "honeycomb" thermal protection system (TPS) for future hypersonic flight vehicles. The studies focus on the effect of honeycomb cell geometry on the TPS heat-shielding performance, honeycomb cell wall buckling characteristics, and the effect of boundary conditions on the TPS thermal bending behavior. The results of the study show that the heat-shielding performance of a TPS panel is very sensitive to change in honeycomb core depth, but insensitive to change in honeycomb cell cross-sectional shape. The thermal deformations and thermal stresses in the TPS panel are found to be very sensitive to the edge support conditions. Slight corrugation of the honeycomb cell walls can greatly increase their buckling strength. Order: Document ID (CASI): 20040073179 Financial Sponsor: NASA Dryden Flight Research Center Back to Top Report Number: NASA/TP-2004-212037; H-2494 Title (Incl. Subtitle): Energy Management of Manned Boost-Glide Vehicles: A Historical Perspective Publication Date: May 2004 Authorized Users: Publicly available Author: Day, Richard E. Author Affil.: NASA Dryden Flight Research Center Abstract: As flight progressed from propellers to jets to rockets, the propulsive energy grew exponentially. With the development of rocket-only boosted vehicles, energy management of these boost-gliders became a distinct requirement for the unpowered return to base, alternate landing site, or water-parachute landing, starting with the X-series rocket aircraft and terminating with the present-day Shuttle. The problem presented here consists of: speed (kinetic energy) - altitude (potential energy) - steep glide angles created by low lift-to-drag ratios (L/D) - distance to landing site - and the bothersome effects of the atmospheric characteristics varying with altitude. The primary discussion regards post-boost, stabilized glides; however, the effects of centrifugal and geopotential acceleration are discussed as well. The aircraft and spacecraft discussed here are the X-1, X-2, X-15, and the Shuttle; and to a lesser, comparative extent, Mercury, Gemini, Apollo, and lifting bodies. The footprints, landfalls, and methods developed for energy management are also described. The essential tools required for energy management - simulator planning, instrumentation, radar, telemetry, extended land or water range, Mission Control Center (with specialist controllers), and emergency alternate landing sites - were first established through development of early concepts and were then validated by research flight tests. Order: Document ID (CASI): 20040058111 Financial Sponsor: NASA Dryden Flight Research Center Back to Top Report Number: NASA/TP-2004-212849; H-2548 Title (Incl. Subtitle): Debonding Stress Concentrations in a Pressurized Lobed Sandwich-Walled Generic Cryogenic Tank Publication Date: May 2004 Authorized Users: Publicly available Author: Ko, William L. Author Affil.: NASA Dryden Flight Research Center Abstract: A finite-element stress analysis has been conducted on a lobed composite sandwich tank subjected to internal pressure and cryogenic cooling. The lobed geometry consists of two obtuse circular walls joined together with a common flat wall. Under internal pressure and cryogenic cooling, this type of lobed tank wall will experience open-mode (a process in which the honeycomb is stretched in the depth direction) and shear stress concentrations at the junctures where curved wall changes into flat wall (known as a curve-flat juncture). Open-mode and shear stress concentrations occur in the honeycomb core at the curve-flat junctures and could cause debonding failure. The levels of contributions from internal pressure and temperature loading to the open-mode and shear debonding failure are compared. The lobed fuel tank with honeycomb sandwich walls has been found to be a structurally unsound geometry because of very low debonding failure strengths. The debonding failure problem could be eliminated if the honeycomb core at the curve-flat juncture is replaced with a solid core. Order: Document ID (CASI): 20040058113 Financial Sponsor: NASA Dryden Flight Research Center Back to Top

	Comparison of Theoretical and Experimental Unsteady Aerodynamics of Linear Oscillating Cascade With Supersonic Leading-Edge Locus
	Channel Temperature Model for Microwave AlGaN/GaN HEMTs on SiC and Sapphire MMICs in High Power, High Efficiency SSPAs
	Quantitative Rainbow Schlieren Deflectometry as a Temperature Diagnostic for Spherical Flames
	Superalloy Lattice Block Structures
	Modeling the Nonlinear, Strain Rate Dependent Deformation of Woven Ceramic Matrix Composites With Hydrostatic Stress Effects Included
	Validation of Radio Frequency Telemetry Concept in the Presence of Biological Tissue-Like Stratified Media
	A Reconfigurable Communications System for Small Spacecraft
	Detailed Microstructural Characterization of the Disk Alloy ME3
	Measurement of Initial Conditions at Nozzle Exit of High Speed Jets
	Prospects for Breakthrough Propulsion From Physics
	Oxidation of Ultra High Temperature Ceramics in Water Vapor
	Tensile Creep Fracture of Polycrystalline Near-Stoichiometric NiAl Back to Top
	Report Number: NASA/TM-2004-211820; E-13512 Title (Incl. Subtitle): Comparison of Theoretical and Experimental Unsteady Aerodynamics of Linear Oscillating Cascade With Supersonic Leading-Edge Locus Publication Date: June 2004 Authorized Users: Publicly available Author: Ramsey, John K.; Erwin, Dan Author Affil.: NASA Glenn Research Center; Ohio State Univ. Abstract: An experimental influence coefficient technique was used to obtain unsteady aerodynamic influence coefficients and, consequently, unsteady pressures for a cascade of symmetric airfoils oscillating in pitch about mid-chord. Stagger angles of 0 deg and 10 deg were investigated for a cascade with a gap-to-chord ratio of 0.417 operating at an axial Mach number of 1.9, resulting in a supersonic leading-edge locus. Reduced frequencies ranged from 0.056 to 0.2. The influence coefficients obtained determine the unsteady pressures for any interblade phase angle. The unsteady pressures were compared with those predicted by several algorithms for interblade phase angles of 0 deg and 180 deg. Order: Document ID (CASI): 20040082334 Financial Sponsor: NASA Glenn Research Center Back to Top Report Number: NASA/TM-2004-212900; E-14315-1 Title (Incl. Subtitle): Channel Temperature Model for Microwave AlGaN/GaN HEMTs on SiC and Sapphire MMICs in High Power, High Efficiency SSPAs Publication Date: June 2004 Authorized Users: Publicly available Author: Freeman, Jon C. Author Affil.: NASA Glenn Research Center Abstract: A key parameter in the design trade-offs made during AlGaN/GaN HEMTs development for microwave power amplifiers is the channel temperature. An accurate determination can, in general, only be found using detailed software; however, a quick estimate is always helpful, as it speeds up the design cycle. This paper gives a simple technique to estimate the channel temperature of a generic microwave AlGaN/GaN HEMT on SiC or Sapphire, while incorporating the temperature dependence of the thermal conductivity. The procedure is validated by comparing its predictions with the experimentally measured temperatures in microwave devices presented in three recently published articles. The model predicts the temperature to within 5 to 10 percent of the true average channel temperature. The calculation strategy is extended to determine device temperature in power combining MMICs for solid-state power amplifiers (SSPAs). Order: Document ID (CASI): 20040082339 Financial Sponsor: NASA Glenn Research Center Back to Top Report Number: NASA/TM-2004-212955; AIAA Paper 2004-0958; E-14351-1 Title (Incl. Subtitle): Quantitative Rainbow Schlieren Deflectometry as a Temperature Diagnostic for Spherical Flames Publication Date: June 2004 Authorized Users: Publicly available Author: Feikema, Douglas A. Author Affil.: NASA Glenn Research Center Abstract: Numerical analysis and experimental results are presented to define a method for quantitatively measuring the temperature distribution of a spherical diffusion flame using Rainbow Schlieren Deflectometry in microgravity. First, a numerical analysis is completed to show the method can suitably determine temperature in the presence of spatially varying species composition. Also, a numerical forward-backward inversion calculation is presented to illustrate the types of calculations and deflections to be encountered. Lastly, a normal gravity demonstration of temperature measurement in an axisymmetric laminar, diffusion flame using Rainbow Schlieren deflectometry is presented. The method employed in this paper illustrates the necessary steps for the preliminary design of a Schlieren system. The largest deflections for the normal gravity flame considered in this paper are 7.4 x 10(-4) radians which can be accurately measured with 2 meter focal length collimating and decollimating optics. The experimental uncertainty of deflection is less than 5 x 10(-5) radians. Order: Document ID (CASI): 20040082340 Financial Sponsor: NASA Glenn Research Center Back to Top Report Number: NASA/TM-2004-213109; E-14448 Title (Incl. Subtitle): Superalloy Lattice Block Structures Publication Date: June 2004 Authorized Users: Publicly available Author: Nathal, M. V.; Whittenberger, J. D.; Hebsur, M. G.; Kantzos, P. T.; Krause, D. L. Author Affil.: NASA Glenn Research Center; NASA Glenn Research Center; Ohio Aerospace Inst.; Ohio Aerospace Inst.; NASA Glenn Research Center Abstract: Initial investigations of investment cast superalloy lattice block suggest that this technology will yield a low cost approach to utilize the high temperature strength and environmental resistance of superalloys in lightweight, damage tolerant structural configurations. Work to date has demonstrated that relatively large superalloy lattice block panels can be successfully investment cast from both IN-718 and Mar-M247. These castings exhibited mechanical properties consistent with the strength of the same superalloys measured from more conventional castings. The lattice block structure also accommodates significant deformation without failure, and is defect tolerant in fatigue. The potential of lattice block structures opens new opportunities for the use of superalloys in future generations of aircraft applications that demand strength and environmental resistance at elevated temperatures along with low weight. Order: Document ID (CASI): 20040082395 Financial Sponsor: NASA Glenn Research Center Back to Top Report Number: NASA/TM-2004-213125; E-14619 Title (Incl. Subtitle): Modeling the Nonlinear, Strain Rate Dependent Deformation of Woven Ceramic Matrix Composites With Hydrostatic Stress Effects Included Publication Date: June 2004 Authorized Users: Publicly available Author: Goldberg, Robert K.; Carney, Kelly S. Author Affil.: NASA Glenn Research Center; NASA Glenn Research Center Abstract: An analysis method based on a deformation (as opposed to damage) approach has been developed to model the strain rate dependent, nonlinear deformation of woven ceramic matrix composites with a plain weave fiber architecture. In the developed model, the differences in the tension and compression response have also been considered. State variable based viscoplastic equations originally developed for metals have been modified to analyze the ceramic matrix composites. To account for the tension/compression asymmetry in the material, the effective stress and effective inelastic strain definitions have been modified. The equations have also been modified to account for the fact that in an orthotropic composite the in-plane shear stiffness is independent of the stiffness in the normal directions. The developed equations have been implemented into a commercially available transient dynamic finite element code, LS-DYNA, through the use of user defined subroutines (UMATs). The tensile, compressive, and shear deformation of a representative plain weave woven ceramic matrix composite are computed and compared to experimental results. The computed values correlate well to the experimental data, demonstrating the ability of the model to accurately compute the deformation response of woven ceramic matrix composites. Order: Document ID (CASI): 20040082455 Financial Sponsor: NASA Glenn Research Center Back to Top Report Number: NASA/TM-2004-213127; E-14377-1 Title (Incl. Subtitle): Validation of Radio Frequency Telemetry Concept in the Presence of Biological Tissue-Like Stratified Media Publication Date: June 2004 Authorized Users: Publicly available Author: Miranda, Felix A.; Simons, Rainee N.; Haal, David G. Author Affil.: NASA Glenn Research Center; NASA Glenn Research Center; ZIN Technologies, Inc. Abstract: In this paper we discuss a novel radio frequency (RF) telemetry concept for biomedical applications. The concept consists of a miniaturized spiral inductor/antenna for bio-MEMS sensors and an external pick-up antenna integrated into a handheld device. The measured relative signal strength in the presence of biological phantoms ranged from 5.9 to 7.5 dB for antenna separations of 5 and 10 cm. These relative signal strengths are easily measurable, therefore validating the RF telemetry concept for biomedical applications. Order: Document ID (CASI): 20040082462 Financial Sponsor: NASA Glenn Research Center Back to Top Report Number: NASA/TM-2004-212534; E-14098 Title (Incl. Subtitle): A Reconfigurable Communications System for Small Spacecraft Publication Date: May 2004 Authorized Users: Publicly available Author: Kifle, Muli; Chu, Pong P. Author Affil.: NASA Glenn Research Center; Cleveland State Univ. Abstract: Two trends of NASA missions are the use of multiple small spacecraft and the development of an integrated space network. To achieve these goals, a robust and agile communications system is needed. Advancements in field programmable gate array (FPGA) technology have made it possible to incorporate major communication and network functionalities in FPGA chips; thus this technology has great potential as the basis for a reconfigurable communications system. This report discusses the requirements of future space communications, reviews relevant issues, and proposes a methodology to design and construct a reconfigurable communications system for small scientific spacecraft. Order: Document ID (CASI): 20040074329 Financial Sponsor: NASA Glenn Research Center Back to Top Report Number: NASA/TM-2004-213066; E-14533 Title (Incl. Subtitle): Detailed Microstructural Characterization of the Disk Alloy ME3 Publication Date: May 2004 Authorized Users: Publicly available Author: Gabb, Timothy P.; Garg, Anita; Ellis, David L.; O'Connor, Kenneth M. Author Affil.: NASA Glenn Research Center; Toledo Univ.; NASA Glenn Research Center; NASA Glenn Research Center Abstract: The advanced powder metallurgy disk alloy ME3 was designed using statistical screening and optimization of composition and processing variables in the NASA/General Electric/Pratt & Whitney HSR/EPM disk program to have extended durability for large disks at maximum temperatures of 600 to 700 C. Scaled-up disks of this alloy were then produced at the conclusion of that program to demonstrate these properties in realistic disk shapes. The objective of the present study was to assess the microstructural characteristics of these ME3 disks at two consistent locations, in order to enable estimation of the variations in microstructure across each disk and across several disks of this advanced alloy. Scaled-up disks processed in the HSR/EPM Compressor/Turbine Disk program had been sectioned, machined into specimens, and tested in tensile, creep, fatigue, and fatigue crack growth tests by NASA Glenn Research Center, in cooperation with General Electric Engine Company and Pratt & Whitney Aircraft Engines. For this study, microstructures of grip sections from tensile specimens in the bore and rim were evaluated from these disks. The major and minor phases were identified and quantified using transmission electron microscopy (TEM). Particular attention was directed to the .' precipitates, which along with grain size can predominantly control the mechanical properties of superalloy disks. Order: Document ID (CASI): 20040074383 Financial Sponsor: NASA Glenn Research Center Back to Top Report Number: NASA/TM-2004-212392; AIAA Paper 2001-2143; E-13969 Title (Incl. Subtitle): Measurement of Initial Conditions at Nozzle Exit of High Speed Jets Publication Date: May 2004 Authorized Users: Publicly available Author: Panda, J.; Zaman, K. B. M. Q.; Seasholtz, R. G. Author Affil.: Ohio Aerospace Inst.; NASA Glenn Research Center; NASA Glenn Research Center Abstract: The time averaged and unsteady density fields close to the nozzle exit (0.1 less than or = x/D less than or = 2, x: downstream distance, D: jet diameter) of unheated free jets at Mach numbers of 0.95, 1.4, and 1.8 were measured using a molecular Rayleigh scattering based technique. The initial thickness of shear layer and its linear growth rate were determined from time-averaged density survey and a modeling process, which utilized the Crocco-Busemann equation to relate density profiles to velocity profiles. The model also corrected for the smearing effect caused by a relatively long probe length in the measured density data. The calculated shear layer thickness was further verified from a limited hot-wire measurement. Density fluctuations spectra, measured using a two-Photomultiplier-tube technique, were used to determine evolution of turbulent fluctuations in various Strouhal frequency bands. For this purpose spectra were obtained from a large number of points inside the flow; and at every axial station spectral data from all radial positions were integrated. The radially-integrated fluctuation data show an exponential growth with downstream distance and an eventual saturation in all Strouhal frequency bands. The initial level of density fluctuations was calculated by extrapolation to nozzle exit. Order: Document ID (CASI): 20040073436 Financial Sponsor: NASA Glenn Research Center Back to Top Report Number: NASA/TM-2004-213082; E-14560 Title (Incl. Subtitle): Prospects for Breakthrough Propulsion From Physics Publication Date: May 2004 Authorized Users: Publicly available Author: Millis, Marc G. Author Affil.: NASA Glenn Research Center Abstract: "Space drives", "Warp drives", and "Wormholes:" these concepts may sound like science fiction, but they are being written about in reputable journals. To assess the implications of these emerging prospects for future spaceflight, NASA supported the Breakthrough Propulsion Physics Project from 1996 through 2002. This Project has three grand challenges: (1) Discover propulsion that eliminates the need for propellant; (2) Discover methods to achieve hyper-fast travel; and (3) Discover breakthrough methods to power spacecraft. Because these challenges are presumably far from fruition, and perhaps even impossible, a special emphasis is placed on selecting incremental and affordable research that addresses the critical issues behind these challenges. Of 16 incremental research tasks completed by the project and from other sponsors, about a third were found not to be viable, a quarter have clear opportunities for sequels, and the rest remain unresolved. Order: Document ID (CASI): 20040070788 Financial Sponsor: NASA Glenn Research Center Back to Top Report Number: NASA/TM-2004-212923; E-14363 Title (Incl. Subtitle): Oxidation of Ultra High Temperature Ceramics in Water Vapor Publication Date: April 2004 Authorized Users: Publicly available Author: Nguyen, QuynhGiao N.; Opila, Elizabeth J.; Robinson, Raymond C. Author Affil.: NASA Glenn Research Center; Cleveland State Univ.; QSS Group, Inc. Abstract: Ultra High Temperature Ceramics (UHTCs) including HfB2 + 20v/0 SiC (HS), ZrB2 + 20v/0 SiC (ZS), and ZrB2 + 30v/0 C + 14v/0 SiC (ZCS) have been investigated for use as potential aeropropulsion engine materials. These materials were oxidized in water vapor (90 percent) using a cyclic vertical furnace at 1 atm. The total exposure time was 10 h at temperatures of 1200, 1300, and 1400 C. CVD SiC was also evaluated as a baseline for comparison. Weight change, X-ray diffraction analyses, surface and cross-sectional SEM and EDS were performed. These results are compared with tests ran in a stagnant air furnace at temperatures of 1327 C for 100 min, and with high pressure burner rig (HPBR) results at 1100 and 1300 C at 6 atm for 50 h. Low velocity water vapor does not make a significant contribution to the oxidation rates of UHTCs when compared to stagnant air. The parabolic rate constants at 1300 C, range from 0.29 to 16.0 mg(sup 2)cm(sup 4)/h for HS and ZCS, respectively, with ZS results between these two values. Comparison of results for UHTCs tested in the furnace in 90 percent water vapor with HPBR results was difficult due to significant sample loss caused by spallation in the increased velocity of the HPBR. Total recession measurements are also reported for the two test environments. Order: Document ID (CASI): 20040073473 Financial Sponsor: NASA Glenn Research Center Back to Top Report Number: NASA/TM-2004-213051; E-14487 Title (Incl. Subtitle): Tensile Creep Fracture of Polycrystalline Near-Stoichiometric NiAl Publication Date: May 2004 Authorized Users: Publicly available Author: Raj, Sai V. Author Affil.: NASA Glenn Research Center Abstract: Tensile creep fracture behavior of polycrystalline near-stoichiometric NiAl has been studied between 700 and 1200 K under initial applied stresses varying between 10 and 200 MPa. The stress exponent for fracture varied between 5.0 and 10.7 while the activation energy for fracture was 250 +/- 22 kJ/mol. The fracture life was inversely proportional to the secondary creep rate in accordance with the Monkman-Grant relation although there was extensive scatter in the data. This observation suggests that the fracture life for near-stoichiometric NiAl was influenced by creep under these stress and temperature conditions. Several different fracture morphologies were observed. Transgranular ductile cleavage fracture occurs at 700 K and at the higher stresses at 800 K. The fracture mode transitions to transgranular creep fracture at 900 and 1000 K and at lower stresses at 800 K, while plastic rupture and grain boundary cavitation occur at 1100 and 1200 K. An experimental fracture mechanism map is constructed for near-stoichiometric NiAl. Order: Document ID (CASI): 20040074331 Financial Sponsor: NASA Glenn Research Center Back to Top

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Johnson Space Center

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Kennedy Space Center

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Langley Research Center

	Model Update of a Micro Air Vehicle (MAV) Flexible Wing Frame with Uncertainty Quantification
	Evaluation and Analysis of F-16XL Wind Tunnel Data From Static and Dynamic Tests
	A Sensitivity Study of the Aircraft Vortex Spacing System (AVOSS) Wake Predictor Algorithm to the Resolution of Input Meteorological Profiles
	Shell Buckling Design Criteria Based on Manufacturing Imperfection Signatures
	Cloud-Aerosol LIDAR and Infrared Pathfinder Satellite Observation (CALIPSO) Spacecraft: Independent Technical Assessment
	Textbook Multigrid Efficiency for Leading Edge Stagnation
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	Report Number: NASA/TM-2004-213232 Title (Incl. Subtitle): Model Update of a Micro Air Vehicle (MAV) Flexible Wing Frame with Uncertainty Quantification Publication Date: July 2004 Authorized Users: Publicly available Author: Reaves, Mercedes C.; Horta, Lucas G.; Waszak, Martin R.; Morgan, Benjamin G. Author Affil.: NASA Langley Research Center; NASA Langley Research Center; NASA Langley Research Center; Kentucky Univ. Abstract: This paper describes a procedure to update parameters in the finite element model of a Micro Air Vehicle (MAV) to improve displacement predictions under aerodynamics loads. Because of fabrication, materials, and geometric uncertainties, a statistical approach combined with Multidisciplinary Design Optimization (MDO) is used to modify key model parameters. Static test data collected using photogrammetry are used to correlate with model predictions. Results show significant improvements in model predictions after parameters are updated; however, computed probabilities values indicate low confidence in updated values and/or model structure errors. Lessons learned in the areas of wing design, test procedures, modeling approaches with geometric nonlinearities, and uncertainties quantification are all documented. Order: Document ID (CASI): 20040082497 Financial Sponsor: NASA Langley Research Center Back to Top
	Report Number: NASA/TM-2004-213234; L-18380 Title (Incl. Subtitle): Evaluation and Analysis of F-16XL Wind Tunnel Data From Static and Dynamic Tests Publication Date: June 2004 Authorized Users: Publicly available Author: Kim, Sungwan; Murphy, Patrick C.; Klein, Vladislav Author Affil.: NASA Langley Research Center; NASA Langley Research Center; George Washington Univ. Abstract: A series of wind tunnel tests were conducted in the NASA Langley Research Center as part of an ongoing effort to develop and test mathematical models for aircraft rigid-body aerodynamics in nonlinear unsteady flight regimes. Analysis of measurement accuracy, especially for nonlinear dynamic systems that may exhibit complicated behaviors, is an essential component of this ongoing effort. In this report, tools for harmonic analysis of dynamic data and assessing measurement accuracy are presented. A linear aerodynamic model is assumed that is appropriate for conventional forced-oscillation experiments, although more general models can be used with these tools. Application of the tools to experimental data is demonstrated and results indicate the levels of uncertainty in output measurements that can arise from experimental setup, calibration procedures, mechanical limitations, and input errors. Order: Document ID (CASI): 20040084067 Financial Sponsor: NASA Langley Research Center Back to Top
	Report Number: NASA/TM-2004-213239; L-18383 Title (Incl. Subtitle): A Sensitivity Study of the Aircraft Vortex Spacing System (AVOSS) Wake Predictor Algorithm to the Resolution of Input Meteorological Profiles Publication Date: June 2004 Authorized Users: Publicly available Author: Rutishauser, David K.; Butler, Patrick; Riggins, Jamie Author Affil.: NASA Langley Research Center; NASA Langley Research Center; NASA Langley Research Center Abstract: The AVOSS project demonstrated the feasibility of applying aircraft wake vortex sensing and prediction technologies to safe aircraft spacing for single runway arrivals. On average, AVOSS provided spacing recommendations that were less than the current FAA prescribed spacing rules, resulting in a potential airport efficiency gain. Subsequent efforts have included quantifying the operational specifications for future Wake Vortex Advisory Systems (WakeVAS). In support of these efforts, each of the candidate subsystems for a WakeVAS must be specified. The specifications represent a consensus between the high-level requirements and the capabilities of the candidate technologies. This report documents the beginnings of an effort to quantify the capabilities of the AVOSS Prediction Algorithm (APA). Specifically, the APA horizontal position and circulation strength output sensitivity to the resolution of its wind and turbulence inputs is examined. The results of this analysis have implications for the requirements of the meteorological sensing and prediction systems comprising a WakeVAS implementation. Order: Document ID (CASI): 20040084068 Financial Sponsor: NASA Langley Research Center Back to Top
	Report Number: NASA/TM-2004-212659; L-19007 Title (Incl. Subtitle): Shell Buckling Design Criteria Based on Manufacturing Imperfection Signatures Publication Date: May 2004 Authorized Users: Publicly available Author: Hilburger, Mark W.; Nemeth, Michael P.; Starnes, James H., Jr. Author Affil.: NASA Langley Research Center; NASA Langley Research Center; NASA Langley Research Center Abstract: An analysis-based approach .for developing shell-buckling design criteria for laminated-composite cylindrical shells that accurately accounts for the effects of initial geometric imperfections is presented. With this approach, measured initial geometric imperfection data from six graphite-epoxy shells are used to determine a manufacturing-process-specific imperfection signature for these shells. This imperfection signature is then used as input into nonlinear finite-element analyses. The imperfection signature represents a "first-approximation" mean imperfection shape that is suitable for developing preliminary-design data. Comparisons of test data and analytical results obtained by using several different imperfection shapes are presented for selected shells. Overall, the results indicate that the analysis-based approach presented for developing reliable preliminary-design criteria has the potential to provide improved, less conservative buckling-load estimates, and to reduce the weight and cost of developing buckling-resistant shell structures. Order: Document ID (CASI): 20040077039 Financial Sponsor: NASA Langley Research Center Back to Top
	Report Number: NASA/TM-2004-213231/VERSION-0.01; NESC-RP-04-01/03-001-E-Version-0.01; L-18363/VERSION-0.01 Title (Incl. Subtitle): Cloud-Aerosol LIDAR and Infrared Pathfinder Satellite Observation (CALIPSO) Spacecraft: Independent Technical Assessment Publication Date: June 2004 Authorized Users: Publicly available Author: Gilbrech, Richard J.; McManamen, John P.; Wilson, Timmy R.; Robinson, Frank; Schoren, William R. Author Affil.: NASA Langley Research Center; NASA Langley Research Center; NASA Langley Research Center; NASA Glenn Research Center; NASA Glenn Research Center Abstract: CALIPSO is a joint science mission between the CNES, LaRC and GSFC. It was selected as an Earth System Science Pathfinder satellite mission in December 1998 to address the role of clouds and aerosols in the Earth's radiation budget. The spacecraft includes a NASA light detecting and ranging (LIDAR) instrument, a NASA wide-field camera and a CNES imaging infrared radiometer. The scope of this effort was a review of the Proteus propulsion bus design and an assessment of the potential for personnel exposure to hydrazine propellant. Order: Document ID (CASI): 20040077040 Financial Sponsor: NASA Langley Research Center Back to Top
	Report Number: NASA/TM-2004-213037; L-19023 Title (Incl. Subtitle): Textbook Multigrid Efficiency for Leading Edge Stagnation Publication Date: May 5, 2004 Authorized Users: Publicly available Author: Diskin, Boris; Thomas, James L.; Mineck, Raymond E. Author Affil.: National Inst. of Aerospace; NASA Langley Research Center; NASA Langley Research Center Abstract: A multigrid solver is defined as having textbook multigrid efficiency (TME) if the solutions to the governing system of equations are attained in a computational work which is a small (less than 10) multiple of the operation count in evaluating the discrete residuals. TME in solving the incompressible inviscid fluid equations is demonstrated for leading-edge stagnation flows. The contributions of this paper include (1) a special formulation of the boundary conditions near stagnation allowing convergence of the Newton iterations on coarse grids, (2) the boundary relaxation technique to facilitate relaxation and residual restriction near the boundaries, (3) a modified relaxation scheme to prevent initial error amplification, and (4) new general analysis techniques for multigrid solvers. Convergence of algebraic errors below the level of discretization errors is attained by a full multigrid (FMG) solver with one full approximation scheme (FAS) cycle per grid. Asymptotic convergence rates of the FAS cycles for the full system of flow equations are very fast, approaching those for scalar elliptic equations. Order: Document ID (CASI): 20040081104 Financial Sponsor: NASA Langley Research Center; NASA Langley Research Center Back to Top

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Marshall Space Flight Center

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Stennis Space Center

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Wallops Flight Center

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Last Update: August 03, 2004