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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 487 records · Page 27

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NASA NTRS1992

Direct-Interface, Fusible Heat Sink

Nonventing, regenerable, and self-contained heat sink absorbs heat in melting of ice by direct contact with forced flow of warm water. Elastic bladder contains water and ice. Connectors designed to prevent leaks easily connectable and disconnectable. Female portions embedded in wall of heat sink. After water frozen, male portions inserted and flow of warm water initiated. Water melts ice in and around female connectors, then flow passes between ice and bladder from inlet to outlet. Component of low-power portable refrigerator to operate for short time in picnic or camp setting.

Lomax, Curtis↗

NASA NTRS1992

Modified Spot Welder Solders Flat Cables

Soldering device, essentially modified spot welder, melts high-melting-temperature solders without damaging plastic insulation on flat electrical cables. Solder preform rests on exposed conductor of cable, under connector pin. Electrodes press pin/preform/conductor sandwich together and supply pulse of current to melt preform, bonding pin to conductor. Anvil acts as support and heat sink. Device used to solder flexible ribbon cables to subminiature pin connectors.

Haehner, Carl L.↗

NASA NTRS1991

Reflection Effects in Multimode Fiber Systems Utilizing Laser Transmitters

A number of optical communication lines are now in use at NASA-Kennedy for the transmission of voice, computer data, and video signals. Now, all of these channels use a single carrier wavelength centered near 1300 or 1550 nm. Engineering tests in the past have given indications of the growth of systematic and random noise in the RF spectrum of a fiber network as the number of connector pairs is increased. This noise seems to occur when a laser transmitter is used instead of a LED. It has been suggested that the noise is caused by back reflections created at connector fiber interfaces. Experiments were performed to explore the effect of reflection on the transmitting laser under conditions of reflective feedback. This effort included computer integration of some of the instrumentation in the fiber optic lab using the Lab View software recently acquired by the lab group. The main goal was to interface the Anritsu Optical and RF spectrum analyzers to the MacIntosh II computer so that laser spectra and network RF spectra could be simultaneously and rapidly acquired in a form convenient for analysis. Both single and multimode fiber is installed at Kennedy. Since most are multimode, this effort concentrated on multimode systems.

Bates, Harry E.↗

NASA NTRS1992

High temperature solder device for flat cables

A high temperature solder device for flat cables includes a microwelder, an anvil which acts as a heat sink and supports a flexible flat ribbon cable that is to be connected to a multiple pin connector. The microwelder is made from a modified commercially available resistance welding machine such as the Split Tip Electrode microwelder by Weltek, which consists of two separate electrode halves with a removable dielectric spacer in between. The microwelder is not used to weld the items together, but to provide a controlled compressive force on, and energy pulse to, a solder preform placed between a pin of the connector and a conductor of the flexible flat ribbon cable. When the microwelder is operated, an electric pulse will flow down one electrode, through the solder preform and back up the other electrode. This pulse of electrical energy will cause the solder preform to heat up and melt, joining the pin and conductor.

Haehner, Carl L.↗

NASA NTRS1989

Summary of activities

Four space projects' activities are summarized. Design work on the Mars Penetrator Project, in cooperation with the NASA Ames Research Center, is being continued. Efforts are focused on the drilling mechanism which must penetrate the martian subsurface soil to collect and retrieve an uncontaminated sample. The new design consists of a rotary-percussive drill mechanism. This mechanism is optimum for dry drilling, necessary to avoid contamination of the soil sample, in many different soil types. The need for a small, relatively inexpensive device to study the chemical structure of this martian soil was also established. The egg design was chosen for its low cost compared to other systems and potential for a large number of eggs to be deployed on the martian surface. The design process included analysis of the dynamics of reentry, dissipation of heat during reentry, impact with the surface, access to undisturbed soil samples, and ability to gather samples from the soil at three depths. The egg consists of the reentry systems, soil probe lifting system, soil probe package, gas chromatograph, transmitter, and battery power supply. The egg must function only once, but is designed to withstand one martian year. The Mars Mole is designed as a rover-based device which penetrates the martian soil to a depth of up to 10 m, obtains a sample of soil, and returns it to the surface for analysis. The mole was designed to meet the following specifications: (1) weight less than 10 kg; (2) size less than 20 x 20 x 30 cm; (3) power less than 100 W; (4) ability to obtain a sample of at least 5 cc; (5) ability to penetrate fine, loose sand; and (6) need to obtain at least one sample. The space station umbilical connector project is a device which provides the translational motion of the connectors on the Space Station Freedom to allow engagement for power and data transfer. The design is capable of delivering a 20 lb force within the necessary tolerances and will operate reliably in the space environment.

Source record↗

NASA NTRS1994

Bipolar Ag-Zn battery

The silver-zinc (AgZn) battery system has been unique in its ability to safely satisfy high power demand applications with low mass and volume. However, a new generation of defense, aerospace, and commercial applications will impose even higher power demands. These new power demands can be satisfied by the development of a bipolar battery design. In this configuration the power consuming, interelectrode current conductors are eliminated while the current is then conducted via the large cross-section electrode substrate. Negative and positive active materials are applied to opposite sides of a solid silver foil substrate. In addition to reducing the weight and volume required for a specified power level, the output voltage performance is also improved as follows. Reduced weight through: elimination of the plastic cell container; elimination of plate leads and intercell connector; and elimination of internal plate current collector. Increased voltage through: elimination of resistance of current collector; elimination of resistance of plate lead; and elimination of resistance of intercell connector. EPI worked previously on development of a secondary bipolar silver zinc battery. This development demonstrated the electrical capability of the system and manufacturing techniques. One difficulty with this development was mechanical problems with the seals. However, recent improvements in plastics and adhesives should eliminate the major problem of maintaining a seal around the periphery of the bipolar module. The seal problem is not as significant for a primary battery application or for a requirement for only a few discharge cycles. A second difficulty encountered was with activation (introducing electrolyte into the cell) and with venting gas from the cell without loss of electrolyte. During previous work, the following projections for energy density were made from test data for a high power system which demonstrated in excess of 50 discharge/charge cycles. Projected system power = 100 kilowatts; discharge time = 30 seconds; discharge current density = 1.75 amps/sq in.; system weight = 86 lbs (9.7 WH/lb); and system volume = 1071 cu. in. (.78 WH/cu. in.). EPI is currently working on a development program to produce a bipolar silver-zinc battery design for NASA. The potential application would be to power electromechanical actuators for space launch vehicles.

Giltner, L. John↗

NASA NTRS1995

High-voltage space-plasma interactions measured on the PASP Plus test arrays

The Photovoltaic Array Space Power Plus Diagnostics (PASP Plus) experiment was developed by the Air Force's Phillips Laboratory with support from NASA's Lewis Research Center. It was launched on the Advanced Photovoltaic and Electronics EXperiments (APEX) satellite on August 3, 1994 into a 70 degree inclination, 363 km by 2550 km elliptical orbit. This orbit allows the investigation of space plasma effects on high-voltage operation (leakage current at positive voltages and arcing at negative voltages) in the perigee region. PASP Plus is testing twelve solar arrays. There are four planar Si arrays: an old standard type (used as a reference), the large-cell Space Station Freedom (SSF) array, a thin 'APSA' array, and an amorphous Si array. Next are three GaAs on Ge planar arrays and three new material planar arrays, including InP and two multijunction types. Finally, there are two concentrator arrays: a reflective-focusing Mini-Cassegrainian and a Fresnel-lens focusing Mini-Dome. PASP Plus's diagnostic sensors include: Langmuir probe to measure plasma density, an electrostatic analyzer (ESA) to measure the 30 eV to 30 KeV electron/ion spectra and determine vehicle negative potential during positive biasing, and a transient pulse monitor (TPM) to characterize the arcs that occur during the negative biasing. Through positive biasing of its test arrays, PASP Plus investigated the snapover phenomenon, which took place over the range of +100 to +300 V. It was found that array configurations where the interconnects are shielded from the space plasma (i.e., the concentrators or arrays with 'wrap-through' connectors) have lower leakage current. The concentrators exhibited negligible leakage current over the whole range up to +500 V. In the case of two similar GaAs on Ge arrays, the one with 'wrap-through' connectors had lower leakage current than the one with conventional interconnects. Through negative biasing, PASP Plus investigated the arcing rates of its test arrays. The standard Si array, with its old construction (exposed rough-surface interconnects), arced significantly over a wide voltage and plasma-density range. The other arrays arced at very low rates, mostly at voltages greater than -350 V and plasma densities near or greater than 10(exp 5)/cm(exp -3). AS expected according to theory, arcing was more prevalent when array temperatures were cold (based on biasing in eclipse).

Guidice, Donald A.↗

NASA NTRS1995

Design of object-oriented distributed simulation classes

Distributed simulation of aircraft engines as part of a computer aided design package is being developed by NASA Lewis Research Center for the aircraft industry. The project is called NPSS, an acronym for 'Numerical Propulsion Simulation System'. NPSS is a flexible object-oriented simulation of aircraft engines requiring high computing speed. It is desirable to run the simulation on a distributed computer system with multiple processors executing portions of the simulation in parallel. The purpose of this research was to investigate object-oriented structures such that individual objects could be distributed. The set of classes used in the simulation must be designed to facilitate parallel computation. Since the portions of the simulation carried out in parallel are not independent of one another, there is the need for communication among the parallel executing processors which in turn implies need for their synchronization. Communication and synchronization can lead to decreased throughput as parallel processors wait for data or synchronization signals from other processors. As a result of this research, the following have been accomplished. The design and implementation of a set of simulation classes which result in a distributed simulation control program have been completed. The design is based upon MIT 'Actor' model of a concurrent object and uses 'connectors' to structure dynamic connections between simulation components. Connectors may be dynamically created according to the distribution of objects among machines at execution time without any programming changes. Measurements of the basic performance have been carried out with the result that communication overhead of the distributed design is swamped by the computation time of modules unless modules have very short execution times per iteration or time step. An analytical performance model based upon queuing network theory has been designed and implemented. Its application to realistic configurations has not been carried out.

Schoeffler, James D.↗

NASA NTRS1995

Design of Object-Oriented Distributed Simulation Classes

Distributed simulation of aircraft engines as part of a computer aided design package being developed by NASA Lewis Research Center for the aircraft industry. The project is called NPSS, an acronym for "Numerical Propulsion Simulation System". NPSS is a flexible object-oriented simulation of aircraft engines requiring high computing speed. It is desirable to run the simulation on a distributed computer system with multiple processors executing portions of the simulation in parallel. The purpose of this research was to investigate object-oriented structures such that individual objects could be distributed. The set of classes used in the simulation must be designed to facilitate parallel computation. Since the portions of the simulation carried out in parallel are not independent of one another, there is the need for communication among the parallel executing processors which in turn implies need for their synchronization. Communication and synchronization can lead to decreased throughput as parallel processors wait for data or synchronization signals from other processors. As a result of this research, the following have been accomplished. The design and implementation of a set of simulation classes which result in a distributed simulation control program have been completed. The design is based upon MIT "Actor" model of a concurrent object and uses "connectors" to structure dynamic connections between simulation components. Connectors may be dynamically created according to the distribution of objects among machines at execution time without any programming changes. Measurements of the basic performance have been carried out with the result that communication overhead of the distributed design is swamped by the computation time of modules unless modules have very short execution times per iteration or time step. An analytical performance model based upon queuing network theory has been designed and implemented. Its application to realistic configurations has not been carried out.

Schoeffler, James D.↗

NASA NTRS2002

SEE Design Guide and Requirements for Electrical Deadfacing

The purpose of this design guide is to present information for understanding and mitigating the potential hazards associated with de-mating and mating powered electrical connectors on space flight vehicles. The process of staging is a necessary function in the launching of space vehicles and in the deployment of satellites, and now in manned assembly of systems in space. During this electrical interconnection process, various environments may be encountered that warrant the restriction of the voltage and current present across the pins of an electrical connector prior to separation, mating, or in a static open non-mated configuration. This process is called deadfacing. These potentially hazardous environments encompass the obvious explosive fuel vapors and human shock hazard, to multiple Electro-Magnetic Interference (EMI) phenomena related to the rapid rate of change in current as well as exposure to Radio Frequency (RF) fields.

Berki, Joe M.↗

NASA NTRS1988

Space station architecture, module, berthing hub, shell assembly, berthing mechanism and utility connection channel

A space station (20) includes a plurality of modules (24) and berthing hubs (22), joined by interconnections (26) which are sideways connectable. The modules (24) and hubs (22) are fastened together in a triangular configuration in three dimensions. The interconnections (26) include a pair of opposed, axially aligned, flanged ports (50) and a clamp latch (52) formed from a plurality of sections (54, 56 and 58) hinged along their length and extending circumferentially around the flanged ports (50). A hermetic seal (63) is formed between the ports (50). A utilities connection channel (68) extends between the ports (50). The channel (68) has a shell (70) with utilities connectors (74) movable between an extended position to mating connectors in the modules (24) and a withdrawn position. Assembly sequence and common module shell structure is detailed.

Cohen, Marc M.↗

NASA NTRS1980

Mount assembly for porous transition panel at annular combustor outlet

A gas turbine engine combustor assembly of annular configuration has outer and inner walls made up of a plurality of axially extending multi-layered porous metal panels joined together at butt joints therebetween and each outer and inner wall including a transition panel of porous metal defining a combustor assembly outlet supported by a combustor mount assembly including a stiffener ring having a side undercut thereon fit over a transition panel end face; and wherein an annular weld joins the ring to the end face to transmit exhaust heat from the end face to the stiffener ring for dissipation from the combustor; a combustor pilot member is located in axially spaced, surrounding relationship to the end face and connector means support the stiffener ring in free floating relationship with the pilot member to compensate for both radial and axial thermal expansion of the transition panel; and said connector means includes a radial gap for maintaining a controlled flow of coolant from outside of the transition panel into cooling relationship with the stiffener ring and said weld to further cool the end face against excessive heat build-up therein during flow of hot gas exhaust through said outlet.

Sweeney, Ralph B.↗

NASA NTRS1995

Device for testing continuity and/or short circuits in a cable

A device for testing current paths is attachable to a conductor. The device automatically checks the current paths of the conductor for continuity of a center conductor, continuity of a shield and a short circuit between the shield and the center conductor. The device includes a pair of connectors and a circuit to provide for testing of the conductive paths of the cable. The pair of connectors electrically connects the conductive paths of a cable to be tested with the circuit paths of the circuit. The circuit paths in the circuit include indicators to simultaneously indicate the results of the testing.

Hayhurst, Arthur R.↗

NASA NTRS2006

Lithium-Ion Small Cell Battery Shorting Study

Positive Temperature Coefficient (PTC) provides adequate sustained hard short protection for AEA batteries with up to 8 cells in series. PTC cannot protect against sustained hard short in AEA batteries with 10 cells or more in series. Protective fused connector is a proven way to protect larger batteries from hard short damage: a) Hard short not credible in unmanned missions; b) However, recommended during ground handling; c) Inexpensive item. Preliminary diode protection scheme has passed manned space safety requirements for high voltage batteries. SCM confirmed fused connector did not affect battery health, however, this affect of hard short on the its long calendar and cycle life performance needs to be verified.

Pearson, Chris↗

NASA NTRS2008

A Compact, Modular Superconducting Bolometer Array Package

We have designed a detector package to house a superconducting bolometer array, SQUID multiplexers, bias and integration circuitry, optical filtering, electrical connectors, and thermal/mechanical interfaces. This package has been used successfully in the GISMO 2mm camera, a 128-pixel camera operating at a base temperature of 270mK. Operation at lower temperatures is allowed by providing direct heat sinking to the SQUIDS and bias resistors, which generate the bulk of the dissipation in the package. Standard electrical connectors provide reliable contact while enabling quick installation and removal of the package. Careful design has gone into the compensation for differing thermal expansions, the need for heat sinking of the bolometer array, and the placement of magnetic shielding in critical areas. In this presentation, we detail the design and performance of this detector package and describe its scalability to 1280- pixel arrays in the near future.

Benford, Dominic J.↗

NASA NTRS2008

A Compact, Modular Package for Superconducting Bolometer Arrays

As bolometer arrays grow to ever-larger formats, packaging becomes a more critical engineering issue. We have designed a detector package to house a superconducting bolometer array, SQUID multiplexers, bias and filtering circuitry, and electrical connectors. The package includes an optical filter, magnetic shielding, and has well-defined thermal and mechanical interfaces. An early version of this package has been used successfully in the GISMO 2mm camera, a 128-pixel camera operating at a base temperature of 270mK. A more advanced package permits operation at lower temperatures by providing direct heat sinking to the SQUIDS and bias resistors, which generate the bulk of the dissipation in the package. Standard electrical connectors provide reliable contact while enabling quick installation and removal of the package. We describe how the design compensates for differing thermal expansions, allows heat sinking of the bolometer array, and features magnetic shielding in critical areas. We highlight the performance of this detector package and describe its scalability to 1280-pixel arrays in the near future.

Benford, D.↗

NASA NTRS2008

Improved Gas Filling and Sealing of an HC-PCF

An improved packaging approach has been devised for filling a hollow-core photonic-crystal fiber (HC-PCF) with a gas, sealing the HC-PCF to retain the gas, and providing for optical connections and, optionally, a plumbing fitting for changing or augmenting the gas filling. Gas-filled HC-PCFs can be many meters long and have been found to be attractive as relatively compact, lightweight, rugged alternatives to conventional gas-filled glass cells for use as molecular-resonance frequency references for stabilization of lasers in some optical-metrology, lidar, optical-communication, and other advanced applications. Prior approaches to gas filling and sealing of HC-PCFs have involved, variously, omission of any attempt to connectorize the PCF, connectorization inside a vacuum chamber (an awkward and expensive process), or temporary exposure of one end of an HC-PCF to the atmosphere, potentially resulting in contamination of the gas filling. Prior approaches have also involved, variously, fusion splicing of HC-PCFs with other optical fibers or other termination techniques that give rise to Fresnel reflections of about 4 percent, which results in output intensity noise.

Poberezhskiy, Ilya↗

NASA NTRS2009

"Fly-by-Wireless" Vehicles and Evaluations of ISA 100 Applications to Space-Flight

"Fly-by-Wireless" (What is it?) Vision: To minimize cables and connectors and increase functionality across the aerospace industry by providing reliable, lower cost, modular, and higher performance alternatives to wired data connectivity to benefit the entire vehicle/program life-cycle. Focus Areas: 1. System Engineering and Integration to reduce cables and connectors. 2. Provisions for modularity and accessibility in the vehicle architecture. 3. Develop Alternatives to wired connectivity (the "tool box").NASA and Aerospace depend more and more on cost-effective solutions that can meet our requirements. ISA-100.11 a is a promising new standard and NASA wants to evaluate it. NASA should be involved in understanding and contributing to other ISA-100 efforts that contribute to "Fly-by-Wireless" and it's objectives. ISA can engage other aerospace groups that are working on similar goals and obtain more aerospace industry perspective.

Studor, George F.↗