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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 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
NASA NTRS1973

Disconnect unit

A squib-actuated disconnect is characterized by an expandable collet axially extended from a first tension member for receiving in locking engagement a protuberance axially extended from a second tension member. A gas-driven retainer of an annular configuration is also locked in for supporting the collet in locking engagement with the protuberance. The protuberance is axially displaced in response to a firing of an associated squib for thus accommodating a disengagement of the protuberance and the collet.

Alexander, P., Jr.↗
NASA NTRS1976

The development of a positive isolation disconnect

Conceptual design and developmental testing were conducted to determine the feasibility of a highly reliable, positive isolation disconnect (PID) for potential inflight maintenance of Shuttle environmental control/life support system subsystems. The PID design consists of two coupled valves, each capable of fluid isolation through the use of individually operated opposing poppets. An integral level clamping mechanism couples the two valves and locks the bodies together. The coupling lever is locked in position by turning the valve stems that have foolproof caps. The stem shaft has an integral cam that turns inside a yoke to open the poppet to permit fluid flow. Results of 5000 life cycle tests, hydraulic lock test, leakage tests, and pressure drop tests are included.

Rosener, A. A.↗
NASA NTRS1979

Miniature thermocouple disconnect

Commercially available subminiature connector modified for utilization with both flexible and small diameter metal-sheathed thermocouples results in reliable thermocouple for instrumentation on wind-tunnel models smaller than commercial disconnects normally used.

Quinn, K. L.↗
NASA NTRS1978

Interplanetary gas. XXII - Plasma tail disconnection events in comets - Evidence for magnetic field line reconnection at interplanetary sector boundaries

Attention is focused on a form of cometary activity which has been known for some time but is poorly understood: the discarding of a plasma tail by a comet. A link is found between plasma-tail rejections and conditions in the solar wind. A model is presented in which a disconnected tail is the end result of magnetic-field-line reconnection in the cometary ionosphere caused by the traversal of a magnetic sector boundary. Observations of plasma tails appear to be the best and only method at present of mapping the interplanetary sector structure out of the ecliptic plane.

Niedner, M. B., Jr.↗
NASA NTRS1979

Vulnerability of Quick Disconnect Connectors to Carbon Fibers

Unprotected quick disconnect electrical connectors were exposed to fibers of 3mm, 7mm, and 12mm lengths. The average exposure to failure was determined. Results indicate that when the fiber length divided by the airgap is less than one, multiple fibers are required to bridge the gap, and the exposure time to failure rises rapidly.

Meyers, J. A.↗
NASA NTRS1983

Quick-Disconnect Fastener

Proposed quick-disconnect fastener for two or more parts resists shear loads and torque. Device centers parts to be joined, clamps and tightens them into single unit. Potential applications for removable fastener include holding parts for welding, brazing, soldering, riveting, and gluing. Other possible uses are for attaching removable panels and panels with poor access on one side and plugging leaks in pressure vessels.

Palmer, L. W.↗
NASA NTRS1983

Passive Orbital Disconnect Strut (PODS 3), structural and thermal test program

A test program is undertaken to verify that the lifetime of a shuttle launchable dewar can be increased by using passive orbital disconnect struts (PODS). A detailed design is performed on the cold end (PODS-III) portion of the strut. Structural analysis of the thin-wall fiberglass tube allows selection of the optimum winding angle and tube dimensions. Structural tests on the thin-wall fiberglass tube measure both the tension and compression modulus at ambient and LN2 temperatures, the radial deflection versus side load, and the ultimate compression strength of the tube at LN2 temperature. The thermal expansion of the fiberglass tube plus Invar is also measured down to 78 K. The axial gap at the wedge portion of the stem is set based on these data. The PODS-III test article parts are fabricated and assembled using a detailed assembly procedure. The thermal conductants in the orbital configuration was measured for body temperatures between 5 and 40 K. This temperature range covers the predicted ground hold and orbit temperatures for vapor-cooled supports. The test results are then compared with heat leak values predicted before the test began. Side load, axial compression load, and tension load tests conclude the test program.

Parmley, R. T.↗
NASA NTRS1983

Possible observation of a disconnected magnetic structure in a coronal transient

Solar Maximum Mission coronagraph/polarimeter observations of the coronal transient of March 15-16, 1980, which show a bright front convex toward the sun propagating out through the corona at 175 km/sec, are reported. A fan-shaped bright region connecting this front to the inner corona collapses into a narrow, bright ray over the next few hours. These observations are interpreted as resulting from the disconnection of magnetic loops from the underlying prominencelike loop structures seen rising earlier in the event. Other similar inverted arches exist in the C/P data, but are usually seen with poorer temporal resolution.

Illing, R. M. E.↗
NASA NTRS1985

Passive Orbital Disconnect Strut (PODS 3) structural test program

A passive orbital disconnect strut (PODS-3) was analyzed structurally and thermally. Development tests on a graphite/epoxy orbit tube and S glass epoxy launch tube provided the needed data to finalize the design. A detailed assembly procedure was prepared. One strut was fabricated. Shorting loads in both the axial and lateral direction (vs. load angle and location) were measured. The strut was taken to design limit loads at both ambient and 78 K (cold end only). One million fatigue cycles were performed at predicted STS loads (half in tension, half in compression) with the cold end at 78 K. The fatigue test was repeated at design limit loads. Six struts were then fabricated and tested as a system. Axial loads, side loads, and simulated asymmetric loads due to temperature gradients around the vacuum shell were applied. Shorting loads were measured for all tests.

Parmley, R. T.↗
NASA NTRS1985

Test and evaluate passive orbital disconnect struts (PODS 3)

The objectives of the Passive Orbital Disconnect Struts (PODS) test are to evaluate modal resonance of the PODS-III supports to obtain engineering data required for use of PODS-III on flight systems; determine possible performance improvements in large LO2/LH2 space applications. (1) Modal Vibration Tests. A modal resonance survey is performed on a set of six PODS-III struts assembled in a dewar simulator. The survey conditions simulate both launch and orbital loadings of the struts. The orbital load range spans a full to an empty tank. The frequencies surveyed cover the range consistent with Shuttle qualification requirements and the principal resonant modes of the strut system. (2) Benefit study. The benefit of using PODS-III supports on OTV and Space Station LO sub 2 and LH sub 2 reference tanks was compared to nondisconnect supports. Four LO sub 2 and LH sub 2 tanks were studied under various conditions: (1) holding the launch resonance at 35 Hz and varying the orbit resonance; (2) analyzing both full and emtpy tanks at launch; (3) varying orbit boundary temperaure; (4) varying the number of struts; (5) varying orbit times; and (6) using or not using vapor cooling.

Parmley, R. T.↗
NASA NTRS1988

Design and test of a modified passive orbital disconnect strut (PODS-IV)

The design and testing of a modification to the Passive Orbital Disconnect Struts (PODS) III system (designed to reduce support conductance and superfluid-helium-tank dewar weights), PODS IV, are discussed. The PODS IV design was found to achieve a nominal increase of 630-812 percent in side-load resistance over the PODS-III design, with a predicted 15-percent increase in thermal conductance. It is noted that the increase in side-load resistance largely removes the limitation on length of the orbit tube inherent in the PODS III design. The higher resistance of the longer orbit tube results in lower total conductance for the PODS-IV design.

Spradley, Iran E.↗
NASA NTRS1991

Three-Dimensional Navier-Stokes Simulation of Space Shuttle Main Propulsion 17-inch Disconnect Valves

A steady incompressible three-dimensional viscous flow analysis has been conducted for the Space Shuttle external tank/orbiter propellant feed line disconnect flapper valves with upstream elbows. The Navier-Stokes code, INS3D, is modified to handle interior obstacles and a simple turbulence model. The flow solver is tested for stability and convergence in the presence of interior flappers. An under-relaxation scheme has been incorporated to improve the solution stability. Important flow characteristics such as secondary flows, recirculation, vortex and wake regions, and separated flows are observed. Computed values for forces, moments, and pressure drop are in satisfactory agreement with water flow test data covering a maximum tube Reynolds number of 3.5 million. The predicted hydrodynamical stability of the flappers correlates well with the measurements.

Kandula, M.↗
NASA NTRS1991

The last disconnection events in Comet Halley in April 1986

Disconnection event (DE) in cometary plasma physics is the regular loss of the entire plasma tail and the growth of the new one. Analysis of a sequence of DEs that occurred 13-18 April, 1986 shows that they correlate well with a magnetic, sector-boundary crossing and a complex magnetic structure in the solar wind with polarity reversals that occurred about one day later. These events are entirely consistent with sunward, magnetic reconnection as the DE mechanism.

Brandt, John C.↗
NASA NTRS1992

Simulations of coronal disconnection events

The lack of evidence for magnetic disconnection of coronal mass ejections (CMEs) from the sun has long been a puzzle, as it implies a buildup of the interplanetary magnetic field (IMF) magnitude over time. Such a buildup is ruled out by observations. Magnetic reconnection above helmet streamer configurations could provide a mechanism for maintaining the observed relative constancy of the IMF (McComas et al., 1989). McComas et al. (1991) showed observational evidence of reconnection above a streamer. This interpretation is investigated using time-dependent MHD simulations. The opening of new magnetic flux on the sun (as might occur in a CME or other transient event) is modeled as an increase in magnetic flux at the poles of a simulated corona. It is found that this perturbation can in fact cause reconnection above an equatorial helmet streamer, and the resultant density signature is similar to the observations of McComas et al. (1991).

Linker, Jon A.↗
NASA NTRS1992

The disconnection event of 16.0 March 1986 in comet Halley

From kinematic extrapolation of tail/nucleus distance measurements on photographic images in the International Halley Watch (IHW) archive, we calculated the disconnection time of the 16-19 March 1986 event to be 16.0 (plus or minus 0.1) March. The solar wind conditions around Comet Halley at the time of the DE, inferred by corotation of IMP-8 satellite data to the comet, were such that (1) Comet Halley had just crossed the interplanetary magnetic field (IMF) sector boundary; (2) the solar wind density was approximately 8 cm(exp -3); (3) the solar wind speed was approximately 600 km/sec; (4) the IMF magnitude was approximately 8 nT. Given these conditions, we conclude that the most likely cause of the 16.0 March DE was front-side magnetic reconnection, as described in the model of Niedner and Brandt (1978).

Randall, Cora E.↗
NASA NTRS1995

Quick-Connect, Slow-Disconnect Nut

Proposed quick-connect, slow-disconnect nut installs simply by pushing it onto standard bolt or threaded stud. Once installed, removed only by unscrewing it in manner of conventional nut.

Weddendorf, Bruce↗
NASA NTRS1995

Quick-Connect, Slow-Disconnect Bolt

Proposed bolt functions similarly to device described in article "Quick-Connect, Slow-Disconnect Nut" (MFS-28833). Bolt installed in standard threaded hole simply by pushing it into hole. Once inserted, bolt withdrawn only by turning it in conventional way.

Weddendorf, Bruce↗