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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 307 records · Page 17
All sourcesNASA NTRSDOE OSTI
NASA NTRS1998

Qualification of the Tropical Rainfall Measuring Mission Solar Array Deployment System

The Tropical Rainfall Measuring Mission (TRMM) solar arrays are placed into orbital configuration by a complex deployment system. Its two wings each comprise twin seven square solar panels located by a twelve foot articulated boom. The four spring-driven hinge lines per wing are rate-limited by viscous dampers. The wings are stowed against the spacecraft kinematically, and released by five pyrotechnically-actuated mechanisms. Since deployment failure would be catastrophic, a total of 17 deployment tests were completed to qualify the system for the worst cast launch environment. This successful testing culminated in the flawless deployment of the solar arrays on orbit, 15 minutes after launch in November 1997. The custom gravity negation system used to perform deployment testing is modular to allow its setup in several locations, including the launch site in Japan. Both platform and height can be varied, to meet the requirements of the test configuration and the test facility. Its air pad floatation system meets tight packaging requirements, allowing installation while stowed against the spacecraft without breaking any flight interfaces, and avoiding interference during motion. This system was designed concurrently with the deployment system, to facilitate its installation, to aid in the integration of the flight system to the spacecraft, while demonstrating deployment capabilities. Critical parameters for successful testing were alignment of deployment axes and tables to gravity, alignment of table seams to minimize discontinuities, and minimizing pressure drops in the air supply system. Orbital performance was similar to that predicted by ground testing.

Lawrence, Jon↗
NASA NTRS1947

The Load Distribution in Bolted or Riveted Joints in Light-Alloy Structures

This report contains a theoretical discussion of the load distribution in bolted or riveted joints in light-alloy structures which is applicable not only for loads below the limit of proportionality but also for loads above this limit. The theory is developed for double and single shear joints. The methods given are illustrated by numerical examples and the values assumed for the bolt (or rivet) stiffnesses are based partly on theory and partly on known experimental values. It is shown that the load distribution does not vary greatly with the bolt (or rivet) stiffnesses and that for design purposes it is usually sufficient to know their order of magnitude. The theory may also be directly used for spot-welded structures and, with small modifications, for seam-welded structures, The computational work involved in the methods described is simple and may be completed in a reasonable time for most practical problems. A summary of earlier theoretical and experimental investigations on the subject is included in the report.

Vogt, F.↗
NASA NTRS1998

Large Scale Testing of a Foam/Multilayer Insulation Thermal Control System (TCS) for Cryogenic Upper Stages

The development of high energy cryogenic upper stages is essential for the efficient delivery of large payloads to various destinations envisioned in future programs. A key element in such upper stages is cryogenic fluid management (CFM) advanced development/technology. Due to the cost of and limited opportunities for orbital experiments, ground testing must be employed to the fullest extent possible. Therefore, a system level test bed termed the Multipurpose Hydrogen Test Bed (MHTB), which is representative in size and shape (3 meter diameter by 3 meter long with a volume of 18 cubic meters) of a fully integrated space transportation vehicle liquid hydrogen propellant tank has been established. To date, upper stage studies have often baselined the foam/multilayer insulation (FMLI) combination concept; however, hardware experience with the concept is minimal and was therefore selected for the MHTB. The foam element (isofoam SS-1 171 with an average thickness of 3.5 centimeters) is designed to protect against ground hold/ascent flight environments, and allows for the use of a dry nitrogen purge as opposed to the more complex/heavy helium purge subsystem normally required with MLI in cryogenic applications. The MLI (45 layers of Double Aluminized Mylar with Dacron spacers) provides protection in the vacuum environment of space and is designed for an on-orbit storage period of 45 days. Several unique features were incorporated in the MLI concept and included: variable density MLI (reduces weight and radiation losses by changing the layer density), larger but fewer DAM perforations for venting during ascent to orbit (reduces radiation losses), and roll wrap installation of the MLI with a commercially established process to lower assembly man-hours and reduce seam heat leak. Thermal performance testing of the MHTB TCS was conducted during three test series conducted between September 1995 and May 1996. Results for the ground hold portion of the tests were as expected producing an average heat leak of 63 WattS/M2 at an average foam surface temperature of 170 K. The results of the simulated orbit hold test interval produced heat leaks ranging from 0.085 to 0.22 Watts/squareM at warm boundary temperatures of 164K and 305K, respectively. When compared to the performance for a traditional MLI system, a 60% reduction in orbital heat leak or boiloff was measured. Overall, the MHTB TCS demonstrated satisfactory performance for all mission phases required of a cryogenic upper stage.

Hastings, Leon↗
NASA NTRS2001

Wiping Metal Transfer in Friction Stir Welding

Much evidence suggests that as the friction stir pin-tool moves along a weld seam the displacement of metal takes place by a wiping action at the surface of a plug of metal that rotates with the tool. The wiping model is explained and some consequences for the friction stir welding process are drawn.

Nunes, Arthur C., Jr.↗
NASA NTRS2001

X-38 De-Orbit Propulsion Stage MLI Performance Test

This viewgraph presentation gives an overview of the X-38 de-orbit propulsion stage MLI performance tests. The objectives of the research include the testing of the deorbit propulsion stage (DPS) multi-layer insulation (MLI) to determine if MLI performance meets or exceeds that assumed in thermal analysis and to determine the performance degradation due to seams.

Kittredge, Ken↗
NASA NTRS1999

OVERGRID: A Unified Overset Grid Generation Graphical Interface

This paper presents a unified graphical interface and gridding strategy for performing overset grid generation. The interface called OVERGRID has been specifically designed to follow an efficient overset gridding strategy, and contains general grid manipulation capabilities as well as modules that are specifically suited for overset grids. General grid utilities include functions for grid redistribution, smoothing, concatenation, extraction, extrapolation, projection, and many others. Modules specially tailored for overset grids include a seam curve extractor, hyperbolic and algebraic surface grid generators, a hyperbolic volume grid generator, and a Cartesian box grid generator, Grid visualization is achieved using OpenGL while widgets are constructed with Tcl/Tk. The software is portable between various platforms from UNIX workstations to personal computers.

Chan, William M.↗
NASA NTRS1993

Welding Sensor System

A system originally designed for welding components of the huge Space Shuttle external tank led to a laser-based automated welder for industrial use. A laser sensor tracks the seam where two pieces of metal are to be joined, measures gaps, misfits and automatically corrects welding of torch distance and height. A small industrial computer translates the sensor's information to the weld head and records and displays weld data for control purposes and analysis. The system was modified for commercial use by Marshall Space Flight Center (MSFC), Martin Marietta and Applied Research, Inc., which produces the commercial system. Applications are in industrial welding processes that require repetitive operations and a high degree of reliability.

Source record↗
NASA NTRS1989

Clean Room Apparel

American Hospital Supply Corporation (AHSC), Baxter Healthcare Corporation's predecessor, used the NASA informational base on contamination control technology to improve industrial contamination control technology. When a study determined that microscopic body particles escaping through tiny "windows" in woven garments worn by workers were the greatest source of contamination, AHSC developed TYVEK. This non-woven material filters 99% of all particulate matter larger than half a micron. Baxter Healthcare added a polyimide coating which seals and ties down any loose fibers, providing greater durability. Stress points along seams have been minimized to make the garment almost tearproof. Micro-Clean 212 garments are individually packaged and disposable.

Source record↗
NASA NTRS2002

X-38 De-orbit Propulsion Stage MLI Performance Test

This paper presents a performance test of the X-38 Deorbit Propulsion Stage (DPS) Multi-Layer Insulation (MLI) system. The purpose of this test is to determine if MLI performance meets or exceeds thermal analyses requirements and if there is performance degradation due to seams.

Kittredge, Ken↗
NASA NTRS2002

Polymer-Single Wall Carbon Nanotube Composites for Potential Spacecraft Applications

Polymer-single wall carbon nanotube (SWNT) composite films were prepared and characterized as part of an effort to develop polymeric materials with improved combinations of properties for potential use on future spacecraft. Next generation spacecraft will require ultra-lightweight materials that possess specific and unique combinations of properties such as radiation and atomic oxygen resistance, low solar absorptivity, high thermal emissitivity, electrical conductivity, tear resistance, ability to be folded and seamed, and good mechanical properties. The objective of this work is to incorporate sufficient electrical conductivity into space durable polyimides to mitigate static charge build-up. The challenge is to obtain this level of conductivity (10(exp -8) S/cm) without degrading other properties of importance, particularly optical transparency. Several different approaches were attempted to fully disperse the SWNTs into the polymer matrix. These included high shear mixing, sonication, and synthesizing the polymers in the presence of pre-dispersed SWNTs. Acceptable levels of conductivity were obtained at loading levels less than one tenth weight percent SWNT without significantly sacrificing optical properties. Characterization of the nanocomposite films and the effect of SWNT concentration and dispersion on the conductivity, solar absorptivity, thermal emissivity, mechanical and thermal properties were discussed. Fibers and non-woven porous mats of SWNT reinforced polymer nanocomposite were produced using electrospinning.

Park, C.↗
NASA NTRS2003

Thermo-Mechanical Processing in Friction Stir Welds

Friction stir welding is a solid-phase joining, or welding process that was invented in 1991 at The Welding Institute (TWI). The process is potentially capable of joining a wide variety of aluminum alloys that are traditionally difficult to fusion weld. The friction stir welding (FSW) process produces welds by moving a non-consumable rotating pin tool along a seam between work pieces that are firmly clamped to an anvil. At the start of the process, the rotating pin is plunged into the material to a pre-determined load. The required heat is produced by a combination of frictional and deformation heating. The shape of the tool shoulder and supporting anvil promotes a high hydrostatic pressure along the joint line as the tool shears and literally stirs the metal together. To produce a defect free weld, process variables (RPM, transverse speed, and downward force) and tool pin design must be chosen carefully. An accurate model of the material flow during the process is necessary to guide process variable selection. At MSFC a plastic slip line model of the process has been synthesized based on macroscopic images of the resulting weld material. Although this model appears to have captured the main features of the process, material specific interactions are not understood. The objective of the present research was to develop a basic understanding of the evolution of the microstructure to be able to relate it to the deformation process variables of strain, strain rate, and temperature.

Schneider, Judy↗
NASA NTRS2000

Category V Compliant Container for Mars Sample Return Missions

A novel containerization technique that satisfies Planetary Protection (PP) Category V requirements has been developed and demonstrated on the mock-up of the Mars Sample Return Container. The proposed approach uses explosive welding with a sacrificial layer and cut-through-the-seam techniques. The technology produces a container that is free from Martian contaminants on an atomic level. The containerization technique can be used on any celestial body that may support life. A major advantage of the proposed technology is the possibility of very fast (less than an hour) verification of both containment and cleanliness with typical metallurgical laboratory equipment. No separate biological verification is required. In addition to Category V requirements, the proposed container presents a surface that is clean from any, even nonviable organisms, and any molecular fragments of biological origin that are unique to Mars or any other celestial body other than Earth.

Containers↗
NASA NTRS2004

Graphical Analysis of B-737 Airplane Pathloss Data for GPS and Evaluation of Coupling Mitigation Techniques

The use of Portable Electronic Devices (PEDs) onboard commercial airliners is considered to be desirable for many passengers, However, the possibility of Electromagnetic Interference (EMI) caused by these devices may affect flight safety. PEDs may act as transmitters, both intentional and unintentional, and their signals may be detected by the various navigation and communication radios onboard the aircraft. Interference Pathloss (IPL) is defined as the measurement of the radiated field coupling between passenger cabin locations and aircraft communication and navigation receivers, via their antennas. This paper first focuses on IPL measurements for GPS, taken on an out-of-service United Airlines B-737-200. IPL pattern symmetry is verified by analyzing data obtained on the windows of the Port as well as the Starboard side of the aircraft. Further graphical analysis is performed with the door and exit seams sealed with conductive tape in order to better understand the effects of shielding on IPL patterns. Shielding effects are analyzed from window data for VHF and LOC systems. In addition the shielding benefit of applying electrically conductive film to aircraft windows is evaluated for GPS and TCAS systems.

Jafri, Madiha J.↗
NASA NTRS2004

Issues on Fabrication and Evaluation of SiC/SiC Tubes With Various Fiber Architectures

SiC/SiC engine components, high-modulus Sylramic-iBN SiC fiber tows were used to form nine different tubular architectural preforms with 13 mm (0.5 in.) inner diameter and lengths of approx. 75 and 230 mm (approx. 3 and approx, 9 in.). The thin-walled preforms were then coated with a BN interphase and densified with a hybrid SiC matrix using nearly the same process steps previously established for slurry-cast melt-infiltrated Sylramic-iBN/BN/SiC flat panels. The as-fabricated CMC tubes were microstructurally evaluated and tested for tensile hoop and flexural behavior, and some of the tubes were also tested in a low-pressure burner rig test with a high thru-thickness thermal gradient. To date, four general tube scale-up issues have been identified: greater CVI deposits on outer wall than inner wall; increased ply thickness and reduced fiber fraction; poor test standards for accurately determining the hoop strength of a small-diameter tube; and poor hoop strength for architectures with seams or ply ends. The underlying mechanisms and possible methods for their minimization are discussed.

Yun, H. M.↗
NASA NTRS2005

Dual Balloon Concept for Lifting Payloads from the Surface of Venus

Introduction: Two high-rated Venus mission concepts proposed in the National Science Foundation Decadal Survey require a balloon to lift payloads from Venusian surface to high altitudes: Venus Surface Sample Return (VESSR) and Venus In-Situ Explorer (VISE). In case of VESSR the payload is a canister with the surface sample plus a Venus ascent vehicle (VAV), which is a rocket that takes the sample into orbit for rendezvous with an Earth return vehicle. VISE is envisioned as a more limited precursor mission where the surface sample is only taken to high altitudes so that non time-critical analyses can be performed. From the balloon point of view, the only difference between these two missions is that the VESSR payload to be lifted is very much larger than VISE because of the inclusion of the VAV. A key problem is that at the time the decadal survey was published, no high temperature balloon technology existed to implement either mission. Prior technology development efforts had concentrated on a single balloon that could operate across the entire 0-60 km altitude range, tolerating both the sulfuric acid aerosols and the extreme temperatures of -10 to +460 C. However, this problem was unsolved because no combination of sufficiently lightweight balloon material and manufacturing (seaming) technology was ever found to tolerate the high temperatures at the surface.

Kerzhanovich, Viktor V.↗
NASA NTRS2005

Fabrication end Deployment Testing of Meter Solar Sail Quadrants for a Scaleable Square Solar Sail Ground Test System

In order for solar sail propulsion technologies to be considered as a viable option for a wide range of near term practical missions a predictable, stable, reliable, manufactureable, scaleable, and cost effective system must be developed and tested first on earth and then on orbit. The design and development of a Scaleable Square Solar Sail System (S^4) is well underway a t AEC-Able Engineering Co. Inc., and the design and production of the Solar Sails for this system is being carried out by SRS Technologies. In April and May of 2004 a single quadrant 10-meter system was tested at NASA LARC's vacuum chamber and a four quadrant 20-meter system has been designed and built for deployment and testing in the Spring of 2005 at NASA/Glenn Research Center's Plumb Brook Facility. SRS has developed an effective and efficient design for triangular sail quadrants that are supported are three points and provide a flat reflective surface with a high fill factor. This sail design is robust enough for deployments in a one atmosphere, one gravity environment and incorporates several advanced features including adhesiveless seaming of membrane strips, compliant edge borders to allow for film membrane cord strain mismatch without causing wrinkling and low mass (3% of total sail mass) ripstop. This paper will outline the sail design and fabrication process, the lessons learned and the resulting mature production, packaging and deployment processes that have been developed. It will also highlight the scalability of the equipment and processes that were developed to fabricate and package the sails. Based on recent experience, SRS is confidant that flight worthy solar sails in the 40-120-meter size range with areal density in the 4-5g/sq m (sail minus structure) range can be produced with existing technology. Additional film production research will lead to further reductions in film thickness to less than 1 micron enabling production of sails with areal densities as low as 20 g/sq m using the current design resulting in a system areal density of as low as 5.3g/sq m. These areal densities are low enough to allow nearly all of the Solar Sail missions that have been proposed by the scientific community and the fundamental technology required to produce these sails has been demonstrated on the ground test sails that have recently been built. These demonstrations have shown that the technology is mature enough to build sails needed to support critical science missions. Solar Sails will be an enabling technology for NASA's Vision for Space Exploration by allowing communication satellite orbits that can maintain continuous communication with the polar regions of the Moon and Mars and to support solar weather monitoring to provide early warning of solar flares and storms that could threaten the safety of astronauts and other spacecraft.

Laue, Greg↗
NASA NTRS2005

Fabrication and Deployment Testing of Solar Sail Quadrants for a 20-Meter Solar Sail Ground Test System Demonstration

A 20-meter Scalable Square Solar Sail (S(sup 4)) System was produced and successfully completed functional vacuum testing in NASA Glenn's Space Power Facility at Plum Brook Station Ohio in May 2005. The S(sup 4) system was designed and developed by ATK Space Systems, and the design and production of the Solar Sails for this system was carried out by SRS Technologies. The S(sup 4) system consists of a central structure with four deployable carbon fiber masts that support four triangular sails. SRS has developed an effective and efficient design for triangular sail quadrants that are supported at three points and provide a flat reflective surface with a high fill factor. This sail design is robust enough for deployments in a one atmosphere, one gravity environment and incorporates several advanced features including adhesiveless seaming of membrane strips, compliant edge borders to allow for film membrane cord strain mismatch without causing wrinkling and low mass (3% of total sail mass) ripstop. This paper will outline some of the sail design and fabrication processes and the mature production, packaging and deployment processes that have been developed. This paper will also detail the successful ambient and vacuum testing of the sails and the ATK spacecraft structure. Based on recent experience and testing, SRS is confidant that high Technology Readiness Level (TRL) 5-6 solar sails in the 40-120-meter size range with areal density in the 4-5 grams per square meters (sail minus structure) range can be produced with existing technology. Additional film production research will lead to further reductions in film thickness to less than 1 micron enabling production of sails with areal densities as low as 2.0 grams per square meters using the current design, resulting in a system areal densities as low as 5.3 grams per square meters (sail and structure). These areal densities are low enough to allow nearly all of the Solar Sail missions that have been proposed by the scientific community. The fundamental technologies required to produce these systems has been demonstrated on the 20-meter S(sup 4) sails that have recently completed ground testing demonstrating a mature and technology suitable for incorporation into future flight validation and future mission. Solar Sails can support NASA's Vision for Space Exploration by allowing communication satellite orbits that can maintain continuous communication with the polar regions of the Moon and Mars and to support solar weather monitoring to provide early warning of solar flares and storms that could threaten the safety of astronauts and other spacecraft.

Laue, Greg↗
NASA NTRS2005

THERMAL INSULATION SYSTEMS

Thermal insulation systems and with methods of their production. The thermal insulation systems incorporate at least one reflection layer and at least one spacer layer in an alternating pattern. Each spacer layer includes a fill layer and a carrier layer. The fill layer may be separate from the carrier layer, or it may be a part of the carrier layer, i.e., mechanically injected into the carrier layer or chemically formed in the carrier layer. Fill layers contain a powder having a high surface area and low bulk density. Movement of powder within a fill layer is restricted by electrostatic effects with the reflection layer combined with the presence of a carrier layer, or by containing the powder in the carrier layer. The powder in the spacer layer may be compressed from its bulk density. The thermal insulation systems may further contain an outer casing. Thermal insulation systems may further include strips and seams to form a matrix of sections. Such sections serve to limit loss of powder from a fill layer to a single section and reduce heat losses along the reflection layer.

Augustynowicz, Stanislaw D.↗