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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 NTRS1980

Fog dispersion

A study of economically viable techniques for dispersing warm fog at commercial airports is presented. Five fog dispersion techniques are examined: evaporation suppression, downwash, mixing, seeding with hygroscopic material, thermal techniques, and charged particle techniques. Thermal techniques, although effective, were found to be too expensive for routine airport operations, and detrimental to the environment. Seeding or helicopter downwash are practical for small-scale or temporary fog clearing, but are probably not useful for airport operations on a routine basis. Considerable disagreement exists on the capability of charged particle techniques, which stems from the fact that different assumptions and parameter values are used in the analytical models. Recommendations resulting from the review of this technique are listed, and include: experimental measurements of the parameters in question; a study to ascertain possible safety hazards, such as increased electrical activity or fuel ignition during refueling operations which could render charged particle techniques impractical; and a study of a single charged particle generator.

Frost, W.↗
NASA NTRS1982

Flight support system mechanisms

The Flight Support System (FSS) which contains twelve mechanisms (six different types) which are used for retention and positioning of a Multimission Modular Spacecraft (MMS) within the Space Shuttle's cargo bay during launch, retrieval, and servicing missions is described. Retention latches were designed to provide the capability for structural support of the MMS during launch and retrieval, and during servicing operations the mechanisms on the Positioning Platform provide the capability for positioning the MMS in virtually any orientation necessary for the work to be performed. In addition, there are mechanisms for matching and demating umbilical connectors and a mechanism for locking the Positioning Platform during maneuvers. Each Mechanism is driven by a Common Drive Unit. Manual overrides were provided for those mechanisms that would present a safety hazard for the crew, if they should fail.

Source record↗
NASA NTRS1985

An analysis of doping modulated superlattice structures

A new method of growing doping modulated superlattice structures is discussed. This method uses organo-metallic chemical vapor deposition (MO-CVD) with the added feature of controlled plasma in the growth regions. The main objective was to study how the growth environment affected the electronic and optical properties of the superlattice structures. Because a serious safety hazard was discovered in the growth process, no superlattice structures were fabricated and the research on this material had to be terminated. The hazard had to do with the lack of adequate means for the disposal of toxic elemental beryllium.

Buoncristiani, A. M.↗
NASA NTRS1988

Spacecraft Fire-Safety Experiments for Space Station: Technology Development Mission

Definitions, overall descriptions, and preliminary apparatus and instrumentation requirements are presented for three spacecraft fire-safety experiments appropriate for inclusion in a growth-version of the Space Station. The experiments are as follows: 1. Combustion and Flame Spread of Typical Spacecraft Materials in a Low­ Velocity Convective Flow in Low Gravity 2. Fire and Fire-Extinguishant Interactions with Various Fire Scenarios in Low Gravity 3. Smoldering and Deep-Seated Combustion in Low Gravity. The experiments were selected from an assessment of recommendations for advanced technologies for prevention, detection, and control of fires in spacecraft. The experiments and their facilities are intended to constitute a portion of a Spacecraft Fire Safety Technology Development Mission (TDM). Basic requirements for the mission study are that the Space Station is essential for the accomplishment of the experimental objectives and that the technology being developed is appropriate for the growth version of the Space Station. The advantages of these three experiments are that, not only do they explore problems relevant to the Space Station operation and utilization, but also they constitute tests adaptable to two multiuse facilities installed in the Space Station laboratory module, the Combustion Tunnel Facility and the Combustion Facility. Three additional spacecraft fire-safety experiments, essential precursors to the TD M for near-term performance, are also described as follows: 1. Near-Term Testing of Materials for Combustion and Flame Spread 2. Near-Term Extinguishment of Fires in a Low-Gravity Test Bed 3. Post-Fire Recovery of Sensitive Electrical and Electronic Equipment. For all the experiments, the study defines accommodations in terms of first-order space, mass, power, consumables, and crew-time estimates. The study also reviews the key problems to be addressed, namely experiment safety hazards, non-intrusive diagnostics development and waste-products disposal. A preliminary task and time schedule for design, development, and experiment fabrication is proposed.

Youngblood, Wallace W.↗
NASA NTRS1989

Helicopter flights with night-vision goggles: Human factors aspects

Night-vision goggles (NVGs) and, in particular, the advanced, helmet-mounted Aviators Night-Vision-Imaging System (ANVIS) allows helicopter pilots to perform low-level flight at night. It consists of light intensifier tubes which amplify low-intensity ambient illumination (star and moon light) and an optical system which together produce a bright image of the scene. However, these NVGs do not turn night into day, and, while they may often provide significant advantages over unaided night flight, they may also result in visual fatigue, high workload, and safety hazards. These problems reflect both system limitations and human-factors issues. A brief description of the technical characteristics of NVGs and of human night-vision capabilities is followed by a description and analysis of specific perceptual problems which occur with the use of NVGs in flight. Some of the issues addressed include: limitations imposed by a restricted field of view; problems related to binocular rivalry; the consequences of inappropriate focusing of the eye; the effects of ambient illumination levels and of various types of terrain on image quality; difficulties in distance and slope estimation; effects of dazzling; and visual fatigue and superimposed symbology. These issues are described and analyzed in terms of their possible consequences on helicopter pilot performance. The additional influence of individual differences among pilots is emphasized. Thermal imaging systems (forward looking infrared (FLIR)) are described briefly and compared to light intensifier systems (NVGs). Many of the phenomena which are described are not readily understood. More research is required to better understand the human-factors problems created by the use of NVGs and other night-vision aids, to enhance system design, and to improve training methods and simulation techniques.

Brickner, Michael S.↗
NASA NTRS1989

An alternative control structure for telerobotics

A new teletobotic control concept which couples human supervisory commands with computer reasoning is presented. The control system is responsive and accomplishes an operator's commands while providing obstacle avoidance and stable controlled interactions with the environment in the presence of communication time delays. This provides a system which not only assists the operator in accomplishing tasks but modifies inappropriate operator commands which can result in safety hazards and/or equipment damage.

Boissiere, Peter T.↗
NASA NTRS1991

Chemical spray pyrolysis of Tl-Ba-Ca-Cu-O high-T(sub c) superconductors for high-field bitter magnets

The deposition of Tl-Ba-Ca-Cu-O thick films by spray pyrolyzing a Ba-Ca-Cu-O precursor film and diffusing thallium into the film to form the superconducting phase is examined. This approach was taken to reduce exposure to thallium and its health and safety hazards. The Tl-Ba-Ca-Cu-O system was selected because it has very attractive features which make it appealing to device and manufacturing engineering. Tl-Ba-Ca-Cu-O will accommodate a number of superconducting phases. This attribute makes it very forgiving to stoichiometric fluctuations in the bulk and film. It has excellent thermal and chemical stability, and appears to be relatively insensitive to chemical impurities. Oxygen is tightly bound into the systems, consequently there is no orthorhombic (conductor) to tetragonal (insulator) transition which would affect a component's lifetime. More significantly, the thallium based superconductors appear to have harder magnetic properties than the other high-Tc oxide ceramics. Estimates using magnetoresistance measurements indicate that at 77 K Tl2Ba2CaCu2O10 will have an upper critical field, H(sub c2) fo 26 Tesla for applied fields parallel to the c-axis and approximately 1000 Tesla for fields oriented in the a-b plane. Results to date have shown that superconducting films can be reproducibly deposited on 100 oriented MgO substrates. One film had a zero resistance temperature of 111.5 K. Furthermore, x ray diffraction analysis of the films showed preferential c-axis orientation parallel to the plane of the substrate. These results have now made it possible to consider the manufacture of a superconducting tape wire which can be configured into a topology useful for high-field magnet designs. The research which leads to the preparation of these films and plans for further development are reviewed.

Derochemont, L. Pierre↗
NASA NTRS1992

Analysis of debris from Spacelab Space Life Sciences-1

Airborne microbiological and particulate contamination generated aboard Spacelab modules is a potential safety hazard. In order to shed light on the characteristics of these contaminants, microbial and chemical/particulate analyses were performed on debris vacuumed from cabin and avionics air filters in the Space Life Sciences-1 (SLS-1) module of the Space Transportation System 40 (STS-40) mission 1 month after landing. The debris was sorted into categories (e.g., metal, nonmetal, hair/fur, synthetic fibers, food particles, insect fragments, etc.). Elemental analysis of particles was done by energy dispersive analysis of x rays (metals) and Fourier transform infrared spectroscopy (nonmetals). Scanning electron micrographs were done of most particles. Microbiological samples were grown on R2A culture medium and identified. Clothing fibers dominated the debris by volume. Other particles, all attributed to the crew, resulted from abrasions and impacts during missions operations (e.g., paint chips, plastic, electronic scraps and clothing fibers). All bacterial species identified are commonly found in the atmosphere or on the human body. Bacillus sp. was the most frequently seen bacterium. One of the bacterial species, Enterobacter agglomerans, could cause illness in crew members with depressed immune systems.

Caruso, S. V.↗
NASA NTRS1992

Structural dynamics for new launch vehicles

An overview is presented of current studies that will permit more robust designs and reduce the safety hazards of maximum dynamic pressure during launches. Key considerations in the assessment of future operable launch capabilities are the dynamics problems that arise during the initial minutes of transition from the static configuration on the launch pad to the attainment of orbital velocity. Attention is given to a typical attempt to achieve robustness that involves creating a design in which the first bending mode will have a high enough frequency to allow decoupling between the autopilot design and the flexible body dynamics.

Neighbors, Joyce↗
NASA NTRS1989

Metrication report to the Congress

The major NASA metrication activity of 1988 concerned the Space Station. Although the metric system was the baseline measurement system for preliminary design studies, solicitations for final design and development of the Space Station Freedom requested use of the inch-pound system because of concerns with cost impact and potential safety hazards. Under that policy, however use of the metric system would be permitted through waivers where its use was appropriate. Late in 1987, several Department of Defense decisions were made to increase commitment to the metric system, thereby broadening the potential base of metric involvement in the U.S. industry. A re-evaluation of Space Station Freedom units of measure policy was, therefore, initiated in January 1988.

Source record↗
NASA NTRS1994

A very low shock alternative to conventional, pyrotechnically operated release devices

NiTiNOL is best known for its ability to remember a preset shape, even after being 'plastically' deformed. This is accomplished by heating the material to an elevated temperature up to 120 degrees C. However, NiTiNOL has other material and mechanical properties that provide a novel method of structural release. This combination of properties allows NiTiNOL to be used as a mechanical fuse between structural components. When electrical power is applied to the NiTiNOL fuse(s), the material is annealed reducing the mechanical strength to a small fraction of the as-wrought material. The preload then fractures the weakened NiTiNOL fuse(s) and releases the structure. This paper describes the mechanical characteristics of the NiTiNOL allow used in this invention, structural separation design concepts using the NiTiNOL material, and initial test data. Elimination of the safety hazard, high shock levels, and non-reusability inherent with pyrotechnic separation devices allows NiTiNOL actuated release devices to become a viable alternative for aerospace components and systems.

Robinson, Steven P.↗
NASA NTRS1997

Premixed Flame-Vortex Interactions Imaged in Microgravity

A unique experiment makes it now possible to obtain detailed images in microgravity showing how an individual vortex causes the wrinkling, stretching, area increase, and eventual extinction of a premixed flame. The repeatable, controllable flame-vortex interaction represents the fundamental building block of turbulent combustion concepts. New information is provided that is central to turbulent flame models, including measurements of all components of flame stretch, strain, and vorticity. Simultaneous measurements of all components of these quantities are not possible in fully turbulent flames but are possible in the present axisymmetric, repeatable experiment. Advanced PIV diagnostics have been used at one-g and have been developed for microgravity. Numerical simulations of the interaction are being performed at NRL. It is found that microgravity conditions greatly augment the flame wrinkling process. Flame area and the amplitude of wrinkles at zero-g are typically twice that observed at one-g. It is inferred that turbulent flames in microgravity could have larger surface area and thus propagate significantly faster than those in one-g, which is a potential safety hazard. A new mechanism is identified by PIV images that shows how buoyancy retards flame wrinkling at one-g; buoyancy produces new vorticity (due to baroclinic torques) that oppose the wrinkling and the stretch imposed by the original vortex. Microgravity conditions remove this stabilizing mechanism and the amplitude of flame wrinkling typically is found to double. Microgravity also increases the flame speed by a factor of 1.8 to 2.2. Both methane and propane-air flames were studied at the NASA Lewis drop tower. Results indicate that it is important to add buoyancy to models of turbulent flames to simulate the correct flame wrinkling, stretch and burning velocity.

Driscoll, J. F.↗
NASA NTRS1998

Improved Li/BCX Primary Cells for Space Applications

Li/BCX (bromine chloride in thionyl chloride) primary cells have been qualified for flight aboard the space shuttle for over fifteen years. These cells provide high energy density while maintaining an excellent safety record. Recently, changes to the electrolyte have resulted in an improved Li/BCX II system with a lower self-discharge rate. The use of low molarity electrolytes in programs unique to NASA have improved the safety hazards tolerance of these cells while maintaining or increasing their energy density.

Spillman, David M.↗
NASA NTRS2000

Asbestos Free Insulation Development for the Space Shuttle Solid Propellant Rocket Motor (RSRM)

Asbestos has been used for many years as an ablation inhibitor in insulating materials. It has been a constituent of the AS/NBR insulation used to protect the steel case of the RSRM (Reusable Solid Rocket Motor) since its inception. This paper discusses the development of a potential replacement RSRM insulation design, several of the numerous design issues that were worked and processing problems that were resolved. The earlier design demonstration on FSM-5 (Flight Support Motor) of the selected 7% and 11% Kevlar(registered) filled EPDM (KF/EPDM) candidate materials was expanded. Full-scale process simulation articles were built and FSM-8 was manufactured using multiple Asbestos Free (AF) components and materials. Two major problems had to be overcome in developing the AF design. First, bondline corrosion, which occurred in the double-cured region of the aft dome, had to be eliminated. Second, KF/EPDM creates high levels of electrostatic energy (ESE), which does not readily dissipate from the insulation surface. An uncontrolled electrostatic discharge (ESD) of this surface energy during many phases of production could create serious safety hazards. Numerous processing changes were implemented and a conductive paint was developed to prevent exposed external insulation surfaces from generating ESE/ESD. Additionally, special internal instrumentation was incorporated into FSM-8 to record real-time internal motor environment data. These data included inhibitor insulation erosion rates and internal thermal environments. The FSM-8 static test was successfully conducted in February 2000 and much valuable data were obtained to characterize the AF insulation design.

Allred, Larry D.↗
NASA NTRS2000

Development of Thermal Barriers For Solid Rocket Motor Nozzle Joints

Joints in the Space Shuttle solid rocket motors are sealed by O-rings to contain combustion gases inside the rocket that reach pressures of up to 900 psi and temperatures of up to 5500 F. To provide protection for the O-rings, the motors are insulated with either phenolic or rubber insulation. Gaps in the joints leading up to the O-rings are filled with polysulfide joint-fill compounds as an additional level of protection. The current RSRM nozzle-to-case joint design incorporating primary, secondary, and wiper O-rings experiences gas paths through the joint-fill compound to the innermost wiper O-ring in about one out of every seven motors. Although this does not pose a safety hazard to the motor, it is an undesirable condition that NASA and rocket manufacturer Thiokol want to eliminate. Each nozzle-to-case joint gas path results in extensive reviews and evaluation before flights can be resumed. Thiokol and NASA Marshall are currently working to improve the nozzle-to-case joint design by implementing a more reliable J-leg design that has been used successfully in the field and igniter joint. They are also planning to incorporate the NASA Glenn braided carbon fiber thermal barrier into the joint. The thermal barrier would act as an additional level of protection for the O-rings and allow the elimination of the joint-fill compound from the joint.

Steinetz, Bruce M.↗
NASA NTRS2001

Cool Flame Quenching

Cool flame quenching distances are generally presumed to be larger than those associated with hot flames, because the quenching distance scales with the inverse of the flame propagation speed, and cool flame propagation speeds are often times slower than those associated with hot flames. To date, this presumption has never been put to a rigorous test, because unstirred, non-isothermal cool flame studies on Earth are complicated by natural convection. Moreover, the critical Peclet number (Pe) for quenching of cool flames has never been established and may not be the same as that associated with wall quenching due to conduction heat loss in hot flames, Pe approx. = 40-60. The objectives of this ground-based study are to: (1) better understand the role of conduction heat loss and species diffusion on cool flame quenching (i.e., Lewis number effects), (2) determine cool flame quenching distances (i.e, critical Peclet number, Pe) for different experimental parameters and vessel surface pretreatments, and (3) understand the mechanisms that govern the quenching distances in premixtures that support cool flames as well as hot flames induced by spark-ignition. Objective (3) poses a unique fire safety hazard if conditions exist where cool flame quenching distances are smaller than those associated with hot flames. For example, a significant, yet unexplored risk, can occur if a multi-stage ignition (a cool flame that transitions to a hot flame) occurs in a vessel size that is smaller than that associated with the hot quenching distance. To accomplish the above objectives, a variety of hydrocarbon-air mixtures will be tested in a static reactor at elevated temperature in the laboratory (1g). In addition, reactions with chemical induction times that are sufficiently short will be tested aboard NASA's KC-135 microgravity (mu-g) aircraft. The mu-g results will be compared to a numerical model that includes species diffusion, heat conduction, and a skeletal kinetic mechanism, following the work on diffusion-controlled cool flames by Fairlie et,al., 2000.

Pearlman, Howard↗
NASA NTRS2001

Evaluation of the Universal Hand Tool for Metals Processing in Space

The Paton Welding Institute, Kiev, Ukraine, has developed the Universal Hand Tool for processing Metals in the space environment. The Universal is a hand held, 1 kilowatt electron beam welding tool designed to accept attachments to enable welding with and without filler wire, cutting, and coating by vapor deposition. The Marshall Space Flight Center, together with the Paton Institute, designed and developed the International Space Welding Experiment (ISWE) to demonstrate the Universal Welding System during an extravehicular activity on STS-87. ISWE was subsequently demanifested and has not been remanifested at this time. This paper describes the science objectives of ISWE, the safety hazards associated with manual welding in space and the associated resolutions, and the results of ground based development efforts. The Universal was adequate for processing the samples planned for ISWE and was successfully modified to meet shuttle payload constraints. Sample cleanliness and operator training proved to be the primary drivers for the quality of the processed samples.

Russell, Carolyn↗
NASA NTRS1995

Optimal Category-A Helicopter Flight Trajectories for Operation From a Clear Heliport

Engine failure represents a major safety hazard to helicopter operation. As a result, FA certifies helicopters according to their abilities to survive engine failures. Federal Aviation Regulation Part 29 specifies that transport helicopters must be certified as either category A or B. Category-B certification applies to either single or multi-engine helicopters with gross weight less than 20,000 lbs. A Category-B helicopter must be able to land safely in the case of one or all engine failures. There is no requirement for continued flight capability. In contrast, Category-A certification applies to multi-engine helicopters with independent engine systems. It requires that helicopter can continue flight with one engine inoperative (OEI). Therefore, Category-A helicopters are capable of operating from rooftops and oil rigs and flying to areas where no emergency landing sites are available. While there is no maximum weight limit, a Category-A helicopter must be able to satisfy OEI operation requirements within the available runway field. Additional information is contained in the original extended abstract.

Sharma, Vivek↗