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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 1,207 records · Page 67
All sourcesNASA NTRSDOE OSTI
NASA NTRS1978

Collapsible corrugated horn antenna

A horn antenna that is readily collapsible while not in use is described. A number of different sized annular metal rings are arranged in a sequence such that each ring is larger than the one that precedes it in the sequence. A number of thin flexible electrically conductive members attach successive metal rings together physically and connect them together electrically. Each flexible conductive member is attached to make electrical contact between the outside surface of a metal ring and the inside surface of an adjacent metal ring in the sequence.

Barthlome, D. E.↗
NASA NTRS1980

Some features of pararesonance /PR/ whistlers

Pararesonance (PR) whistlers observed in the topside ionosphere by the Dartmouth receiver on Ogo 6 are examined. The study extends that of Walter and Angerami (1969) to higher frequencies and shows that the upper cutoff frequency of PR whistlers closely follows a 1/L to the 4th dependence from 6 to 100 kHz (at L = 2.90 and 1.37, respectively). Most PR whistlers are attached to paralongitudinal (PL) whistlers due, presumably, to intermode coupling. The 'walking trace', or unattached PR whistler, reported by Walter and Angerami is evidently unusual. The upper cutoff frequency follows 1/L to the 4th whether attachment occurs or not. Rising sawtooth appendages starting at the upper cutoff frequency are frequency seen on PR whistlers.

Morgan, M. G.↗
NASA NTRS1982

Automated Solar-Array Assembly

Large arrays are rapidly assembled from individual solar cells by automated production line developed for NASA's Jet Propulsion Laboratory. Apparatus positions cells within array, attaches interconnection tabs, applies solder flux, and solders interconnections. Cells are placed in either straight or staggered configurations and may be connected either in series or in parallel. Are attached at rate of one every 5 seconds.

Soffa, A.↗
NASA NTRS1980

Thermal barrier pressure seal

An apparatus is described for providing thermal and pressure sealing in an elongated space of varying width between adjacent surface of two members. The apparatus is mounted for at least limited lateral movement between the members and may comprise: an elongated support attached to one of the adjacent surfaces; a second elongated support member attached to the other of the adjacent surfaces, and an elongated seal member sandwiched between the first and second support members. In its non-deformed state, the elongated seal member may be substantially cylindrical but capable of deformation to accommodate limited lateral movement between the adjacent surfaces and varying widths of the space.

Bellavia, J., Jr.↗
NASA NTRS1980

Shuttle/payload communications and data systems interface analysis

The payload/orbiter functional command signal flow and telemetry signal flow are discussed. Functional descriptions of the various orbiter communication/avionic equipment involved in processing a command to a payload either from the ground through the orbiter by the payload specialist on the orbiter are included. Functional descriptions of the various orbiter communication/avionic equipment involved in processing telemetry data by the orbiter and transmitting the processed data to the ground are presented. The results of the attached payload/orbiter single processing and data handling system evaluation are described. The causes of the majority of attached payload/orbiter interface problems are delineated. A refined set of required flux density values for a detached payload to communicate with the orbiter is presented.

Huth, G. K.↗
NASA NTRS1980

Shuttle/payload communications and data systems interface analysis: Executive summary

Potential interface compatibility problems associated with interfacing OFT payload elements with orbiter communications and data handling elements that would result from payload or orbit failure to meet interface requirements contained in the orbiter/cargo standard interface specification are identified. The potential interface compatibility problems can be associated with either attached payloads in the payload bay or detached payloads communicating with the orbiter via an RF link. Evaluation of the attached payload orbiter interfaces was made by investigating interface problem areas experienced between the IUS and the orbiter since similar problems could be expected for other payloads.

Source record↗
NASA NTRS1977

Space Fabrication Demonstration System

Progress on fabrication facility (beam builder) support structure control, clamp/weld block, and welding and truss cut off is discussed. The brace attachment design was changed and the design of the weld mechanism was modified which achieved the following system benefits: (1) simplified weld electrode life; (2) reduced weld power requirements; and (3) simplified brace attachment mechanisms. Static and fatigue characteristics of spot welded 2024T3 aluminum joints are evaluated.

Source record↗
NASA NTRS1981

Payload retention latches for the shuttle orbiter

Two latches were designed to mount payloads in the shuttle orbiter bay. Multiple retention latches attach a payload to the sill longerons and another latch device attaches it to the keel. Requirements for each actuator are defined and drive mechanisms are described. Other design aspects discussed include: switch mechanisms, motors, gearboxes, redundancy provisions, structural materials, and lubricants. A preliminary dry lubricant test program is also reviewed and results presented.

Renken, R. D.↗
NASA NTRS1981

Investigation of aerodynamic characteristics of wings having vortex flow using different numerical codes

The aerodynamic characteristics of highly sweptback wings having separation-induced vortex flow were investigated by employing different numerical codes with a view to determining some of the capabilities and limitations of these codes. Flat wings of various configurations-strake wing models, cropped, diamond, arrow and double delta wings, were studied. Cambered and cranked planforms have also been tested. The theoretical results predicted by the codes were compared with the experimental data, wherever possible, and found to agree favorably for most of the configurations investigated. However, large cambered wings could not be successfully modeled by the codes. It appears that the final solution in the free vortex sheet method is affected by the selection of the initial solution. Accumulated span loadings estimated for delta and diamond wings were found to be unusual in comparison with attached flow results in that the slopes of these load curves near the leading edge do not tend to infinity as they do in the case of attached flow.

Reddy, C. S.↗
NASA NTRS1981

Thunderstorm hazards flight research: Storm hazards 1980 overview

A highly instrumented NASA F-106B aircraft, modified for the storm hazards mission and protected against direct lightning strikes, was used in conjunction with various ground based radar and lightning measurement systems to collect data during thunderstorm penetration flights. During 69 thunderstorm penetrations, there were 10 direct lightning strikes to the aircraft. No problems were encountered with any of the aircraft's systems as a result of the strikes and the research instrumentation performed as designed. Electromagnetic characteristics of nine strikes were recorded, and the results of other experiments confirm the theory that X-ray radiation and nitrous oxide gas are being produced by processes associated directly with thunderstorm electric fields and lightning discharges. A better understanding of aircraft lightning attachment mechanisms and strike zones is being accomplished by careful inspection, identification, and documentation of lightning attachment points and swept stroke paths following each strike to the aircraft.

Deal, P. L.↗
NASA NTRS1981

Helmet weight simulator

A device for providing acceleration cues to the helmet of a simulator pilot is described. Pulleys are attached to both shoulders of the pilot. A cable is attached to both sides of the helmet and extends through the pulleys to a takeup reel that is controlled by a torque motor. Control signals are applied to a servo system including the torque motor, the takeup reel and a force transducer which supplies the feedback signal. In one embodiment of the invention the force transducer is in the cable and in another it is in the takeup reel.

Ashworth, B. R.↗
NASA NTRS1981

Automated syringe sampler

A number of sampling services are disposed in a rack which slides into a housing. In response to a signal from an antenna, the circutry elements are activated which provide power individually, collectively, or selectively to a servomechanism thereby moving an actuator arm and the attached jawed bracket supporting an evaculated tube towards a stationary needle. One open end of the needle extends through the side wall of a conduit to the interior and the other open end is maintained within the protective sleeve, supported by a bifurcated bracket. A septum in punctured by the end of the needle within the sleeve and a sample of the fluid medium in the conduit flows through the needle and is transferred to a tube. The signal to the servo is then reversed and the actuator arm moves the tube back to its original position permitting the septum to expand and seal the hole made by the needle. The jawed bracket is attached by pivot to the actuator to facilitate tube replacement.

Purgold, G. C.↗
NASA NTRS1981

Experimental study of the effects of secondary air on the emissions and stability of a lean premixed combustor

Tests were run using a perforated plate flameholder with a relatively short attached recirculation zone and a vee gutter flameholder with a relatively long attached recirculation zone. Combustor streamlines were traced in cold flow tests at ambient pressure. The amount of secondary air entrainment in the recirculation zones of the flameholders was determined by tracer gas testing at cold flow ambient pressure conditions. Combustion tests were caried out at entrance conditions of 0.5 MPa/630K and emission of NOx, CO and unburned hydrocarbons were measured along with lean stability and flashback limits. The degree of entrainment increases as dilution air injection decreases. Flashback appears to be a function of overall equivalence ratio and resistance to flashback increases with increasing combustor entrance velocity. Lean stability limit appears to be a function of both primary zone and flameholder recirculation zone equivalence ratios and resistance to lean blowout increases with increasing combustor entrance velocity.

Roffe, G.↗
NASA NTRS1981

Negative ions in comets

Negative ion sources in comets are identified and cometary plasma effects caused by negative ions are examined. The primary negative ion sources are shown to be: (1) for the inner coma - photodissociation of HCN, electron attachment of OH, and collision with alkalis; (2) in the vicinity of the nucleus - interplanetary dust collisions with the nucleus; and (3) for both the contaminated solar wind region and sporadic discharges in the nonhomogeneous inner coma plasma - dissociative electron attachment and charge inversion during keV positive ion scattering by cometary dust. Negative ion abundance for Halley's Comet has been estimated to be 10 to the -6th - 10 to the -10th of electron densities.

Wekhof, A.↗
NASA NTRS1981

The effects of sidewall boundary layers in two-dimensional subsonic and transonic wind tunnels

A transonic similarity rule which accounts for the effects of attached sidewall boundary layers in two-dimensional wind tunnels is presented along with results of an experimental investigation of sidewall boundary-layer effects. The rule appears valid provided the sidewall boundary layer both remains attached in the vicinity of the model and occupies a small enough fraction of the tunnel width to avoid substantial three-dimensional interaction with the model.

Sewall, W. G.↗
NASA NTRS1983

Assembly of Photovoltaic Arrays

Vacuum holddown fixtures hold photovoltaic solar cells during assembly into array. Tab attachment fixture holds single cell and interconnecting tabs during heat-lamp soldering. Array-layout fixture has computer-scribed layout template and holds cells (with attached tabs) while being placed in position and transferred to array-interconnection fixture, which holds cells during final soldering step. Group of heat lamps on trolley passes slowly over interconnection fixture to heat cells to soldering temperature.

Coyle, P. J.↗
NASA NTRS1982

Design detail verification tests for a lightly loaded open-corrugation graphite-epoxy cylinder

Flat corrugated graphite-epoxy panels were tested in compression to verify selected design details of a ring-stiffened cylinder that was designed to support an axial compressive load of 157.6 kN/m without buckling. Three different sizes of subcomponent panels, with the same basic corrugation geometry, were tested: (1) 60.96-cm-long by 45.72-cm-wide panels to evaluate the local buckling strength of the shell wall design; (2) 91.44-cm-long by 45.72-cm-wide panels to evaluate a longitudinal joint and the load-introduction method; and (3) 254.0-cm-long by 91.44-cm-wide panels with four simulated-ring stiffeners to evaluate the ring-attachment method. The test results indicate that the modified shell-wall design, the longitudinal joint, the load-introduction method, and the stiffener-attachment method for the proposed cylinder have adequate strength to support the design load.

Davis, R. C.↗
NASA NTRS1982

A two-degree-of-freedom flutter mount system with low damping for testing rigid wings at different angles of attack

A wind tunnel model mount system for conducting flutter research using a rigid wing was developed. The wing is attached to a splitter plate so that the two move as one rigid body. The splitter plate is supported away from the tunnel wall by a system of rods with fixed fixed and conditions. The rods flex in such a way that only pitch and plunge oscillations are permitted. At the tunnel wall the rods are attached to a remotely controlled turntable so that angle of attack can be varied. Wind tunnel data obtained by using the mount system are presented for a supercritical and a conventional airfoil. Both classical flutter and stall flutter data are presented.

Farmer, M. G.↗