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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 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
NASA NTRS1996

Surface-Pressure and Flow-Visualization Data at Mach Number of 1.60 for Three 65 deg Delta Wings Varying in Leading-Edge Radius and Camber

An experimental investigation of the effect of leading-edge radius, camber, Reynolds number, and boundary-layer state on the incipient separation of a delta wing at supersonic speeds was conducted at the Langley Unitary Plan Wind Tunnel at Mach number of 1.60 over a free-stream Reynolds number range of 1 x 106 to 5 x 106 ft-1. The three delta wing models examined had a 65 deg swept leading edge and varied in cross-sectional shape: a sharp wedge, a 20:1 ellipse, and a 20:1 ellipse with a -9.750 circular camber imposed across the span. The wings were tested with and without transition grit applied. Surface-pressure coefficient data and flow-visualization data indicated that by rounding the wing leading edge or cambering the wing in the spanwise direction, the onset of leading-edge separation on a delta wing can be raised to a higher angle of attack than that observed on a sharp-edged delta wing. The data also showed that the onset of leading-edge separation can be raised to a higher angle of attack by forcing boundary-layer transition to occur closer to the wing leading edge by the application of grit or the increase in free-stream Reynolds number.

McMillin, S. Naomi↗
NASA NTRS1998

Development of Lead Free Energy Absorber for Space Shuttle Blast Container

The Space Shuttle is connected to the mobile launch platform (MLP) by four aft skirt hold down studs on each solid rocket booster (SRB). Prior to lift-off, the frangible nuts inside the aft skirt blast containers are severed into two nut halves by two pyrotechnic booster cartridges. This action releases the Space Shuttle and allows the hold down studs to eject through the aft skirt bore and then down into the MLP. USBI has been tasked to upgrade the blast container for two specific reasons: (1) To eliminate lead for environmental concerns, and (2) To reduce the chance of nut recontact with the holddown stud. Nut recontact with the stud has been identified as a likely contributor to stud hang-ups. This upgrade will replace the lead liner with a unique open cell aluminum foam material, that has commercial and military uses. The aluminum foam used as an energy absorber is a proven design in many other aerospace/defense applications. Additional benefits of using the open cell, energy absorbent aluminum foam in place of the solid lead liner are: (A) Lead handling/exposure and possible contamination, along with hazardous waste disposal, will be eliminated; (B) Approximately 200 lbs. weight savings will be contributed to each Space Shuttle flight by using aluminum foam instead of lead; (C) The new aluminum liner is designed to catch all shrapnel from frangible nuts, thus virtually eliminating chance of debris exiting the HDP and causing potential damage to the vehicle; and (D) Using the lighter aluminum liner instead of lead, allows for easier assembly and disassembly of blast container elements, which also improves safety, operator handling, and the efficiency of operations.

Balles, Donald↗
NASA NTRS1999

Development of Lead Free Energy Absorber for Space Shuttle Blast Container

The Space Shuttle is connected to the mobile launch platform (MLP) by four aft skirt hold down studs on each solid rocket booster (SRB). Prior to lift-off, the frangible nuts inside the aft skirt blast containers are severed into two nut halves by two pyrotechnic booster cartridges. This action releases the Space Shuttle and allows the hold down studs to eject through the aft skirt bore and then down into the MLP. USBI has been tasked to upgrade the blast container for two specific reasons: (1) To eliminate lead for environmental concerns, and (2) To reduce the chance of nut recontact with the holddown stud. Nut recontact with the stud has been identified as a likely contributor to stud hang-ups. This upgrade will replace the lead liner with a unique open cell aluminum foam material, that has commercial and military uses. The aluminum foam used as an energy absorber is a proven design in many other aerospace/defense applications. Additional benefits of using the open cell, energy absorbent aluminum foam in place of the solid lead liner are: (1) Lead handling / exposure and possible contamination, along with hazardous waste disposal, will be eliminated; (2) Approximately 200 lbs. weight savings will be contributed to each Space Shuttle flight by using aluminum foam instead of lead; (3) The new aluminum liner is designed to catch all shrapnel from frangible nuts, thus virtually eliminating chance of debris exiting the HDP and causing potential damage to the vehicle; (4) Using the lighter aluminum liner instead of lead, allows for easier assembly and disassembly of blast container elements, which also improves safety, operator handling, and the efficiency of operations.

Balles, Donald↗
NASA NTRS2000

Durability Evaluation of a Thin Film Sensor System With Enhanced Lead Wire Attachments on SiC/SiC Ceramic Matrix Composites

An advanced thin film sensor system instrumented on silicon carbide (SiC) fiber reinforced SiC matrix ceramic matrix composites (SiC/SiC CMCs), was evaluated in a Mach 0.3 burner rig in order to determine its durability to monitor material/component surface temperature in harsh environments. The sensor system included thermocouples in a thin film form (5 microns thick), fine lead wires (75 microns diameter), and the bonds between these wires and the thin films. Other critical components of the overall system were the heavy, swaged lead wire cable (500 microns diameter) that contained the fine lead wires and was connected to the temperature readout, and ceramic attachments which were bonded onto the CMCs for the purpose of securing the lead wire cables, The newly developed ceramic attachment features a combination of hoops made of monolithic SiC or SiC/SiC CMC (which are joined to the test article) and high temperature ceramic cement. Two instrumented CMC panels were tested in a burner rig for a total of 40 cycles to 1150 C (2100 F). A cycle consisted of rapid heating to 1150 C (2100 F), a 5 minute hold at 1150 C (2100 F), and then cooling down to room temperature in 2 minutes. The thin film sensor systems provided repeatable temperature measurements for a maximum of 25 thermal cycles. Two of the monolithic SiC hoops debonded during the sensor fabrication process and two of the SiC/SiC CMC hoops failed during testing. The hoops filled with ceramic cement, however, showed no sign of detachment after 40 thermal cycle test. The primary failure mechanism of this sensor system was the loss of the fine lead wire-to-thin film connection, which either due to detachment of the fine lead wires from the thin film thermocouples or breakage of the fine wire.

Lei, Jih-Fen↗
NASA NTRSDate not supplied

Nondestructive Evaluation for the Space Shuttle's Wing Leading Edge

The loss of the Space Shuttle Columbia highlighted concerns about the integrity of the Shuttle's thermal protection system, which includes Reinforced Carbon-Carbon (RCC) on the leading edge. This led NASA to investigate nondestructive evaluation (NDE) methods for certifying the integrity of the Shuttle's wing leading edge. That investigation was performed simultaneously with a large study conducted to understand the impact damage caused by errant debris. Among the many advanced NDE methods investigated for applicability to the RCC material, advanced digital radiography, high resolution computed tomography, thermography, ultrasound, acoustic emission and eddy current systems have demonstrated the maturity and success for application to the Shuttle RCC panels. For the purposes of evaluating the RCC panels while they are installed on the orbiters, thermographic detection incorporating principal component analysis (PCA) and eddy current array scanning systems demonstrated the ability to measure the RCC panels from one side only and to detect several flaw types of concern. These systems were field tested at Kennedy Space Center (KSC) and at several locations where impact testing was being conducted. Another advanced method that NASA has been investigating is an automated acoustic based detection system. Such a system would be based in part on methods developed over the years for acoustic emission testing. Impact sensing has been demonstrated through numerous impact tests on both reinforced carbon-carbon (RCC) leading edge materials as well as Shuttle tile materials on representative aluminum wing structures. A variety of impact materials and conditions have been evaluated including foam, ice, and ablator materials at ascent velocities as well as simulated hypervelocity micrometeoroid and orbital debris impacts. These tests have successfully demonstrated the capability to detect and localize impact events on Shuttle's wing structures. A first generation impact sensing system has been designed for the next Shuttle flight and is undergoing final evaluation for deployment on the Shuttle's first return to flight. This system will employ wireless accelerometer sensors that were qualified for other applications on previous Shuttle flights. These sensors will be deployed on the wing's leading edge to detect impacts on the RCC leading edge panels. The application of these methods will help to insure the continued integrity of the Shuttle wing's leading edge system as the Shuttle flights resume and until their retirement.

Eric I Madaras↗
NASA NTRS1996

Surface-Pressure and Flow-Visualization Data at Mach Number of 1.60 for Three 65 deg Delta Wings Varying in Leading-Edge Radius and Camber

An experimental investigation of the effect of leading-edge radius, camber, Reynolds number, and boundary-layer state on the incipient separation of a delta wing at supersonic speeds was conducted at the Langley Unitary Plan Wind Tunnel at Mach number of 1.60 over a free-stream Reynolds number range of 1 x 106 to 5 x 106 ft-1. The three delta wing models examined had a 65 deg swept leading edge and varied in cross-sectional shape: a sharp wedge, a 20:1 ellipse, and a 20:1 ellipse with a -9.750 circular camber imposed across the span. The wings were tested with and without transition grit applied. Surface-pressure coefficient data and flow-visualization data are electronically stored on the CD-ROM. The data indicated that by rounding the wing leading edge or cambering the wing in the spanwise direction, the onset of leading-edge separation on a delta wing can be raised to a higher angle of attack than that observed on a sharp-edged delta wing. The data also showed that the onset of leading-edge separation can be raised to a higher angle of attack by forcing boundary-layer transition to occur closer to the wing leading edge by the application of grit or the increase in free-stream Reynolds number.

McMIllin, S. Naomi↗
NASA NTRS2013

Method and Apparatus for a Leading Edge Slat on a Wing of an Aircraft

A method and apparatus for managing a flight control surface system. A leading edge device is moved on a leading edge from an undeployed position to a deployed position. The leading edge device has an outer surface, an inner surface, and a deformable fairing attached to the leading edge device such that the deformable fairing covers at least a portion of the inner surface. The deformable fairing changes from a deformed shape to an original shape when the leading edge device is moved to the deployed position. The leading edge device is then moved from the deployed position to the undeployed position, wherein the deformable fairing changes from the original shape to the deformed shape.

Pitt, Dale M.↗
NASA NTRS2016

Method for a Leading Edge Slat on a Wing of an Aircraft

A method for managing a flight control surface system. A leading edge device is moved on a leading edge from an undeployed position to a deployed position. The leading edge device has an outer surface, an inner surface, and a deformable fairing attached to the leading edge device such that the deformable fairing covers at least a portion of the inner surface. The deformable fairing changes from a deformed shape to an original shape when the leading edge device is moved to the deployed position. The leading edge device is then moved from the deployed position to the undeployed position, wherein the deformable fairing changes from the original shape to the deformed shape.

Pitt, Dale M.↗
NASA NTRS2020

Advanced High-Lift Leading-Edge (AHLLE) Technologies for Laminar Wings

This is the Northrop Grumman final report for the Advanced High-Lift Leading-Edge Technologies for Laminar Wings conceptual design and demonstration program performed for the National Aeronautics and Space Administration Langley Research Center. Northrop Grumman conducted conceptual aerodynamic CFD and QFD analysis to downselect two leading-edge concepts for high lift. The effort included aerodynamic analysis to examine instrumentation placement and propulsion analysis to design internal cavity geometry of the high-pressure blown slot configurations. A wind tunnel model design created a 7-foot span model of the complex configuration. A wind tunnel test plan, which included baseline, deflected trailing-edge, blown deflected trailing-edge, blown leading-edge, morphed leading-edge, and blown/morphed leading-edge airfoil configurations was developed. As a result of this program approach, a successful demonstration of high-lift leading-edge technology was reached, and the target goals for improved lift were exceeded by 30% with a maximum section lift coefficient (Cl) of 5.2. Incremental lift coefficient (DCl) of 3.5 and 3.1 was achieved on the two laminar compatible airfoil configurations (at cruise). Our high-lift design yielded a massive 94% lift improvement over conventional high-lift Krueger flap configurations while providing laminar flow capability on the cruise configuration.

High-lift↗
NASA NTRS1994

Ice Lead Orientation Characteristics in the Winter Beaufort Sea

The directional orientations of leads in the winter ice pack of the Beaufort Sea are studied both spatially and temporally. Data from the European Earth Resources Satellite-1 (ERS-1) Synthetic Aperture Radar (SAR) was used. The SAR data was produced in image form at the Alaska SAR Facility (ASF) with 100 x 100 m pixel resolution. The lead ice pixels, which included all non-multiyear ice, were defined using a simple thresholding of the radar backscatter values. The orientations of the leads covering the Beaufort Sea during the period of January through March of 1992 were derived using a lead skeletonization technique. Results show a strong temporal persistence in the distribution and orientation of the leads during this period.

SAR ice lead orientation↗
NASA NTRS2019

Quick-Replacement High-Temperature Superconducting Current Leads for Use in a Research Cryostat

We report the use of a series of high-temperature superconducting leads in a cryostat that require no soldering to replace in the event of a failed lead. The temperature range spanned by the leads is 50 to 3 degrees Kelvin and they typically carry currents up to 4 amperes although they have a much higher capacity in this temperature range. The leads are integrated into the cryostat by clamping both ends to gold-plated copper pads. Support of the leads over the 25-centimeter length is provided by a simple G10 strong back. Details of the clamping interface, measurements of joint resistances, and other interesting observations will be discussed.

Superconductivity↗
NASA NTRS1972

Performance of high speed ball bearings with lead plated retainers in liquid hydrogen for potential use in a radiation environment

Ball bearings (40-mm bore) with lead coated, aluminum-bronze retainers were operated successfully in liquid hydrogen at 30,000 rpm under a thrust load of 1780 newtons (400 lb) for running times up to 15 hours. The lead transfer films on the bearing surfaces prevented galling of bearing components. The lead coated retainers used in this investigation show promise for use in the high radiation environments, where polytetrafluoroethylene (PTFE) based materials are not suitable. Failure was a result of the loss of lead lubricant on the retainer-inner-land and ball-pocket surfaces. The longest bearing life (15 hr) was achieved with a lead coating thickness of 50 micrometers (0.002 in.) on the retainer. Other bearings had lives of 2 to 6 hours.

Wisander, D. W.↗
NASA NTRS1976

Lead isotopic studies of lunar soils - Their bearing on the time scale of agglutinate formation

Fines (smaller than 75 microns) and bulk soil were studied to analyze loss of volatile lead; losses of the order of 10% to 30% radiogenic lead during the production of agglutinates are assessed. Lead isotope data from fine-agglutinate pairs are analyzed for information on the time scale of micrometeorite bombardment, from the chords generated by the data in concordia diagrams. Resulting mean lead loss ages were compared to spallogenic gas exposure ages for all samples. Labile parentless radiogenic Pb residing preferentially on or in the fines is viewed as possibly responsible for aberrant lead loss ages. Bulk soils plot above the concordia curve (in a field of excess radiogenic Pb) for all samples with anomalous ages.

Church, S. E.↗
NASA NTRS1978

A theoretical investigation of the aerodynamics of low-aspect-ratio wings with partial leading-edge separation

A numerical method is developed to predict distributed and total aerodynamic characteristics for low aspect-ratio wings with partial leading-edge separation. The flow is assumed to be steady and inviscid. The wing boundary condition is formulated by the quasi-vortex-lattice method. The leading-edge separated vortices are represented by discrete free vortex elements which are aligned with the local velocity vector at mid-points to satisfy the force free condition. The wake behind the trailing-edge is also force free. The flow tangency boundary condition is satisfied on the wing, including the leading- and trailing-edges. Comparison of the predicted results with complete leading-edge separation has shown reasonably good agreement. For cases with partial leading-edge separation, the lift is found to be highly nonlinear with angle of attack.

Mehrotra, S. C.↗
NASA NTRS1979

Influence of optimized leading-edge deflection and geometric anhedral on the low-speed aerodynamic characteristics of a low-aspect-ratio highly swept arrow-wing configuration

An investigation conducted in the Langley 7 by 10 foot tunnel to determine the influence of an optimized leading-edge deflection on the low speed aerodynamic performance of a configuration with a low aspect ratio, highly swept wing. The sensitivity of the lateral stability derivative to geometric anhedral was also studied. The optimized leading edge deflection was developed by aligning the leading edge with the incoming flow along the entire span. Owing to spanwise variation of unwash, the resulting optimized leading edge was a smooth, continuously warped surface for which the deflection varied from 16 deg at the side of body to 50 deg at the wing tip. For the particular configuration studied, levels of leading-edge suction on the order of 90 percent were achieved. The results of tests conducted to determine the sensitivity of the lateral stability derivative to geometric anhedral indicate values which are in reasonable agreement with estimates provided by simple vortex-lattice theories.

Coe, P. L., Jr.↗
NASA NTRS1979

High-performance wings with significant leading-edge thrust at supersonic speeds

A new class of curved-leading-edge wings with which significant levels of leading-edge thrust may be achieved at moderate supersonic speeds is suggested. A recent analysis of the factors limiting such leading-edge thrust has led to a new method for the prediction of attainable leading-edge thrust from subsonic through supersonic speeds for wings of arbitrary planform. Recent supersonic tests of a new wing shape, which largely meets design criteria given by the new prediction method, give evidence of significant levels of leading-edge thrust. The consequent unusually high levels of aerodynamic performance should renew interest in supersonic-cruise vehicle design in general and in cruise-speed selection in particular.

Robins, A. W.↗
NASA NTRS1980

Low-speed aerodynamic characteristics of a highly swept arrow wing configuration with several deflected leading edge concepts

The effectiveness of leading edge concepts for minimizing or controlling leading edge flow separation was studied. Emphasis was placed on low speed performance, stability, and control characteristics of configurations with highly swept wings. Simple deflection of the leading edge, a variable camber leading edge system, and a leading edge vortex flow system were among the concepts studied. The data are presented without analysis.

Gentry, G. L., Jr.↗
NASA NTRS1980

Leading-edge deflection optimization for a highly swept arrow wing configuration

Tests were also conducted to determine the sensitivity of the lateral stability derivative C sub l sub beta to geometric anhedral. The optimized leading edge deflection was developed by aligning the leading edge with the incoming flow along the entire span. Owing to the spanwise variation of upwash, the resulting optimized leading edge was a smooth, continuously warped surface. For the particular configuration studied, levels of leading edge suction on the order of 90 percent were achieved with the smooth, continuously warped leading edge contour. The results of tests conducted to determine the sensitivity of C sub l sub beta to geometric anhedral indicate values of delta C sub l sub beta/delta T which are in reasonable agreement with estimates provided by simple vortex lattice theories.

Coe, P. L., Jr.↗