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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 1,441 records · Page 80
All sourcesNASA NTRSDOE OSTI
NASA NTRS1949

Wind-Tunnel Tests on Various Types of Dive Brakes Mounted in Proximity of the Leading Edge of the Wing

The present report is concerned with a series of tests on a model airplane fitted with four types of dive flaps of various shapes, positions, and incidence located near the leading edge of the wing (from 5 to 20 percent of the wing chord). Tests were also made on a stub airfoil fitted with a ventral dive (located at 8 percent of the wing chord). The hinge moments of the dive flaps were measured.

Lattanzi, Bernardino↗
NASA NTRS2005

Development of Detectability Limits for On-Orbit Inspection of Space Shuttle Wing Leading Edge

At the conclusion of the Columbia Accident Investigation, one of the recommendations of the Columbia Accident Investigation Board (CAIB) was that NASA develop and implement an inspection plan for the Reinforced Carbon-Carbon (RCC) system components of the Space Shuttle. To address these issues, a group of scientists and engineers at NASA Langley Research Center proposed the use of an IR camera to inspect the RCC. Any crack in an RCC panel changes the thermal resistance of the material in the direction perpendicular to the crack. The change in thermal resistance can be made visible by introducing a heat flow across the crack and using an IR camera to image the resulting surface temperature distribution. The temperature difference across the crack depends on the change in the thermal resistance, the length of the crack, the local thermal gradient, and the rate of radiation exchange with the environment. This paper describes how the authors derived the minimum thermal gradient detectability limits for a through crack in an RCC panel. This paper will also show, through the use of a transient, 3-dimensional, finite element model, that these minimum gradients naturally exist on-orbit. The results from the finite element model confirm that there are sufficient thermal gradient to detect a crack on 96% of the RCC leading edge.

Stephan, Ryan A.↗
NASA NTRS2005

Effect of Impact Location on the Response of Shuttle Wing Leading Edge Panel 9

The objective of this paper is to compare the results of several simulations performed to determine the worst-case location for a foam impact on the Space Shuttle wing leading edge. The simulations were performed using the commercial non-linear transient dynamic finite element code, LS-DYNA. These simulations represent the first in a series of parametric studies performed to support the selection of the worst-case impact scenario. Panel 9 was selected for this study to enable comparisons with previous simulations performed during the Columbia Accident Investigation. The projectile for this study is a 5.5-in cube of typical external tank foam weighing 0.23 lb. Seven locations spanning the panel surface were impacted with the foam cube. For each of these cases, the foam was traveling at 1000 ft/s directly aft, along the orbiter X-axis. Results compared from the parametric studies included strains, contact forces, and material energies for various simulations. The results show that the worst case impact location was on the top surface, near the apex.

Lyle, Karen H.↗
NASA NTRS2004

Ultra-High Temperature Ceramic Composites for Leading Edges

Issues associated with the development and use of Ultra-High Temperature Ceramic Composites (UHTCC) for leading edges of hypersonic vehicles will be discussed. These include attachments, constituent selection, processing, oxidation, physical and mechanical properties, and attachments.

Levine, Stanley R.↗
NASA NTRS2005

Nondestructive Evaluation Tests Performed on Space Shuttle Leading- Edge Materials Subjected to Impact

In support of the space shuttle Return To Flight efforts at the NASA Glenn Research Center, a series of nondestructive evaluation (NDE) tests were performed on reinforced carbon/carbon (RCC) composite panels subjected to ballistic foam impact. The impact tests were conducted to refine and verify analytical models of an external tank foam strike on the space shuttle leading edge. The NDE tests were conducted to quantify the size and location of the resulting damage zone as well as to identify hidden damage.

Roth, Don J.↗
NASA NTRS2006

Quasi-Static 3-Point Reinforced Carbon-Carbon Bend Test and Analysis for Shuttle Orbiter Wing Leading Edge Impact Damage Thresholds

Static 3-point bend tests of Reinforced Carbon-Carbon (RCC) were conducted to failure to provide data for additional validation of an LS-DYNA RCC model suitable for predicting the threshold of impact damage to shuttle orbiter wing leading edges. LS-DYNA predictions correlated well with the average RCC failure load, and were good in matching the load vs. deflection. However, correlating the detectable damage using NDE methods with the cumulative damage parameter in LS-DYNA material model 58 was not readily achievable. The difficulty of finding internal RCC damage with NDE and the high sensitivity of the mat58 damage parameter to the load near failure made the task very challenging. In addition, damage mechanisms for RCC due to dynamic impact of debris such as foam and ice and damage mechanisms due to a static loading were, as expected, not equivalent.

Fasanella, Edwin L.↗
NASA NTRS1988

Lead-acid battery construction

The power characteristics of a lead-acid battery are improved by incorporating a dispersion of 1 to 10% by weight of a thermodynamically stable conductivity additive, such as conductive tin oxide coated glass fibers (34) of filamentary glass wool (42) in the positive active layer (32) carried on the grid (30) of the positive plate (16). The avoiding of positive plate reversal to prevent reduction of the tin oxide is accomplished by (a) employing an oversized positive plate and pre-charging it; (b) by pre-discharging the negative plate; and/or (c) by placing a circuit breaker (26) in combination with the plates (16, 18) and terminals (22, 24) to remove the load when the voltage of the positive plate falls below a pre-selected level.

Rowlette, John J.↗
NASA NTRS1983

Lead-acid battery

A light weight lead-acid battery (30) having a positive terminal (36) and a negative terminal (34) and including one or more cells or grid stacks having a plurality of vertically stacked conductive monoplates (10, 20) with positive active material and negative active material deposited on alternating plates in the cell or grid stack. Electrolyte layers (26, 28) positioned between each monoplate are included to provide a battery cell having four sides which is capable of being electrically charged and discharged. Two vertical positive bus bars (42, 43) are provided on opposite sides of the battery cell for connecting the monoplates (10) with positive active material together in parallel current conducting relation. In addition, two negative bus bars (38, 39) on opposite sides of the battery cell each being adjacent the positive bus bars are provided for connecting the monoplates (20) with negative active material together in parallel current conducting relation. The positive (42, 43) and negative (38, 39) bus bars not only provide a low resistance method for connecting the plurality of conductive monoplates of their respective battery terminals (36, 34) but also provides support and structural strength to the battery cell structure. In addition, horizontal orientation of monoplates (10, 20) is provided in a vertical stacking arrangement to reduce electrolyte stratification and short circuiting due to flaking of positive and negative active materials from the monoplates.

Rowlette, John J.↗
NASA NTRS2008

Test-Analysis Correlation for Space Shuttle External Tank Foam Impacting RCC Wing Leading Edge Component Panels

The Space Shuttle Columbia Accident Investigation Board recommended that NASA develop, validate, and maintain a modeling tool capable of predicting the damage threshold for debris impacts on the Space Shuttle Reinforced Carbon-Carbon (RCC) wing leading edge and nosecap assembly. The results presented in this paper are one part of a multi-level approach that supported the development of the predictive tool used to recertify the shuttle for flight following the Columbia Accident. The assessment of predictive capability was largely based on test analysis comparisons for simpler component structures. This paper provides comparisons of finite element simulations with test data for external tank foam debris impacts onto 6-in. square RCC flat panels. Both quantitative displacement and qualitative damage assessment correlations are provided. The comparisons show good agreement and provided the Space Shuttle Program with confidence in the predictive tool.

Lyle, Karen H.↗
NASA NTRS2008

Developing a NASA Lead-Free Policy for Electronics - Lessons Learned

The National Aeronautics and Space Administration (NASA) is not required by United States or international law to use lead-free (Pb-free) electronic systems but international pressure in the world market is making it increasingly important that NASA have a Pb-free policy. In fact, given the international nature of the electronics market, all organizations need a Pb-free policy. This paper describes the factors which must be taken into account in formulating the policy, the tools to aid in structuring the policy and the unanticipated and difficult challenges encountered. NASA is participating in a number of forums and teams trying to develop effective approaches to controlling Pb-free adoption in high reliability systems. The activities and status of the work being done by these teams will be described. NASA also continues to gather information on metal whiskers, particularly tin based, and some recent examples will be shared. The current lack of a policy is resulting in "surprises" and the need to disposition undesirable conditions on a case-by-case basis. This is inefficient, costly and can result in sub-optimum outcomes.

Sampson, Michael J.↗
NASA NTRS2008

Polymer Coats Leads on Implantable Medical Device

Langley Research Center s Soluble Imide (LaRC-SI) was discovered by accident. While researching resins and adhesives for advanced composites for high-speed aircraft, Robert Bryant, a Langley engineer, noticed that one of the polymers he was working with did not behave as predicted. After putting the compound through a two-stage controlled chemical reaction, expecting it to precipitate as a powder after the second stage, he was surprised to see that the compound remained soluble. This novel characteristic ended up making this polymer a very significant finding, eventually leading Bryant and his team to win several NASA technology awards, and an "R&D 100" award. The unique feature of this compound is the way that it lends itself to easy processing. Most polyimides (members of a group of remarkably strong and incredibly heat- and chemical-resistant polymers) require complex curing cycles before they are usable. LaRC-SI remains soluble in its final form, so no further chemical processing is required to produce final materials, like thin films and varnishes. Since producing LaRC-SI does not require complex manufacturing techniques, it has been processed into useful forms for a variety of applications, including mechanical parts, magnetic components, ceramics, adhesives, composites, flexible circuits, multilayer printed circuits, and coatings on fiber optics, wires, and metals. Bryant s team was, at the time, heavily involved with the aircraft polymer project and could not afford to further develop the polymer resin. Believing it was worth further exploration, though, he developed a plan for funding development and submitted it to Langley s chief scientist, who endorsed the experimentation. Bryant then left the high-speed civil transport project to develop LaRC-SI. The result is an extremely tough, lightweight thermoplastic that is not only solvent-resistant, but also has the ability to withstand temperature ranges from cryogenic levels to above 200 C. The thermoplastic s unique characteristics lend it to many commercial applications; uses that Bryant believed would ultimately benefit industry and the Nation. "LaRC-SI," he explains, "is a product created in a government laboratory, funded with money from the tax-paying public. What we discovered helps further the economic competitiveness of the United States, and it was our goal to initiate the technology transfer process to ensure that our work benefited the widest range of people." Several NASA centers, including Langley, have explored methods for using LaRC-SI in a number of applications from radiation shielding and as an adhesive to uses involving replacement of conventional rigid circuit boards. In the commercial realm, LaRC-SI can now be found in several commercial products, including the thin-layer composite unimorph ferroelectric driver and sensor (THUNDER) piezoelectric actuator, another "R&D 100" award winner (Spinoff 2005).

Source record↗
NASA NTRS2009

Detection of Subsurface Material Separation in Shuttle Orbiter Slip-Side Joggle Region of the Wing Leading Edge using Infrared Imaging Data from Arc Jet Tests

The objective of the present study was to determine whether infrared imaging (IR) surface temperature data obtained during arc-jet tests of Space Shuttle Orbiter s reinforced carbon-carbon (RCC) wing leading edge panel slip-side joggle region could be used to detect presence of subsurface material separation, and if so, to determine when separation occurs during the simulated entry profile. Recent thermostructural studies have indicated thermally induced interlaminar normal stress concentrations at the substrate/coating interface in the curved joggle region can result in local subsurface material separation, with the separation predicted to occur during approach to peak heating during reentry. The present study was an attempt to determine experimentally when subsurface material separations occur. A simplified thermal model of a flat RCC panel with subsurface material separation was developed and used to infer general surface temperature trends due to the presence of subsurface material separation. IR data from previously conducted arc-jet tests on three test specimens were analyzed: one without subsurface material separation either pre or post test, one with pre test separation, and one with separation developing during test. The simplified thermal model trend predictions along with comparison of experimental IR data of the three test specimens were used to successfully infer material separation from the arc-jet test data. Furthermore, for the test specimen that had developed subsurface material separation during the arc-jet tests, the initiation of separation appeared to occur during the ramp up to the peak heating condition, where test specimen temperature went from 2500 to 2800 F.

Daryabeigi, Kamran↗
NASA NTRS1935

The Effect of Lateral Inclination of the Thrust Axis and of Sweepback of the Leading Edge of the Wing on Propulsive and Net Efficiencies of a Wing-Nacelle-Propeller Combination

This report describes and gives the results of tests made to determine the effect of lateral inclination of the propeller thrust axis to the direction of flight. A wing-nacelle-propeller combination with the nacelle axis located successively parallel to and at 15 degrees to the perpendicular to the leading edge of a wing was tested with the combination at several angles of yaw. Tests of the wing alone at the same angles of yaw were also made. The data are presented in the usual graphic form. An increase in propulsive efficiency with increase in angle of the thrust axis was found. The change in net efficiency, found by charging the whole nacelle drag to the power unit, was negligible, however, within the range of the tests.

Wood, Donald H.↗
NASA NTRS2009

Using Volcanic Ash to Remove Dissolved Uranium and Lead

Experiments have shown that significant fractions of uranium, lead, and possibly other toxic and/or radioactive substances can be removed from an aqueous solution by simply exposing the solution, at ambient temperature, to a treatment medium that includes weathered volcanic ash from Pu'u Nene, which is a cinder cone on the Island of Hawaii. Heretofore, this specific volcanic ash has been used for an entirely different purpose: simulating the spectral properties of Martian soil. The treatment medium can consist of the volcanic ash alone or in combination with chitosan, which is a natural polymer that can be produced from seafood waste or easily extracted from fungi, some bacteria, and some algae. The medium is harmless to plants and animals and, because of the abundance and natural origin of its ingredient( s), is inexpensive. The medium can be used in a variety of ways and settings: it can be incorporated into water-filtration systems; placed in contact or mixed with water-containing solids (e.g., soils and sludges); immersed in bodies of water (e.g., reservoirs, lakes, rivers, or wells); or placed in and around nuclear power plants, mines, and farm fields.

McKay, David S.↗
NASA NTRS2009

Turbulent Wing-Leading-Edge Correlation Assessment for the Shuttle Orbiter

This study was conducted in support of the Orbiter damage assessment activity that takes place for each Shuttle mission since STS-107 (STS - Space Transportation System). As part of the damage assessment activity, the state of boundary layer (laminar or turbulent) during reentry needs to be estimated in order to define the aerothermal environment on the Orbiter. Premature turbulence on the wing leading edge (WLE) is possible if a surface irregularity promotes early transition and the resulting turbulent wedge flow contaminates the WLE flow. The objective of this analysis is to develop a criterion to determine if and when the flow along the WLE experiences turbulent heating given an incoming turbulent boundary layer that contaminates the attachment line. The data to be analyzed were all obtained as part of the MH-13 Space Shuttle Orbiter Aerothermodynamic Test conducted on a 1.8%-scale Orbiter model at Calspan/University of Buffalo Research Center in the Large Energy National Shock Tunnels facility. A rational framework was used to develop a means to assess the state of the WLE flow on the Orbiter during reentry given a contaminated attachment-line flow. Evidence of turbulent flow on the WLE has been recently documented for a few STS missions during the Orbiter s flight history, albeit late in the reentry trajectory. The criterion developed herein will be compared to these flight results.

King, Rudolph A.↗