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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 289 records · Page 16

All sources NASA NTRS DOE OSTI

NASA NTRS1986

Damage-Free Relief-Valve Disassembly

Tool safely disassembles relief valves without damage to sensitive parts. Relief-valve disassembly tool used to extract valve nozzle from its housing. Holding device on tool grops nozzle. When user strikes hammer against impact disk, holding device pulls nozzle from press fit. Previously, nozzle dislodged by striking spindle above it, but practice often damaged retaining screw. New tool removes nozzle directly. With minor modifications, tool adapted to valves from different manufacturers.

Haselmaier, H.↗

NASA NTRS1983

Detailed performance analysis of the A.A.D. - concept B

New concepts for engine performance improvement are seen through the adoption of heat regeneration techniques; advanced methods to enhance the combustion; and higher efficiency air handling machinery, such as the positive displacement helical screw expander and compressor. Each of these concepts plays a particular role in engine performance improvement. First regeneration has a great potential for achieving higher engine thermal efficiency through the recovery of waste energy. Although the concept itself is not new (this technique is used in the gas turbine), the application to reciprocating internal combustion engines is quite unusual and presents conceptual difficulties. The second important area is better control of the combustion process in terms of heat transfer characteristics, combustion products, and heat release rate. The third area for performance improvement is in the adoption of high efficiency air handling machinery. In particular, positive displacement helical expander and compressor exhibit an extremely high efficiency over a wide range of operating conditions.

Sekar, R.↗

NASA NTRS1985

An Elastic Analysis of a Plated Bone to Determine Fracture Gap Motion

An elastic analysis to determine fracture gap motions occurring in the osteotomized and plated canine femur was performed using the finite element program NASTRAN. The femur was idealized as a hollow right cylinder, and transverse anisotropy was assumed for the elastic properties of the bone. A 3-D 360 degree model consisting of 224 isoparametric quadrilateral hexahedral and 11 beam elements was created. A range of plate stiffnesses was tested by varying the modulus of elasticity of the plate from 207 GPa to 1 GPA. Moments were applied in the plane of the plate, about the axis of the plate, and in the plane of the screws. Results showed that, for plates of typical geometry and elastic modulus under 10 GPa, the contribution to fracture gap motion occurring due to deformation in the bone was negligible compared to that contribution from deformation in the plate.

Cooke, F. W.↗

NASA NTRS1984

Steps towards 8m honeycomb mirrors. V - A method for polishing aspheres as fast as f/1

The present method for the polishing of near-f/1 aspherics employs a lap whose shape is continuously changed under computer control as it moves over the rigid mirror blank. Required changes of radius, astigmatism, and coma in a circular lap are accomplished by means of edge-bending levers and tensioning members that use screw actuators. Attention is given to the case of an f/1, 8-m diameter paraboloid whose mirror blank has been cast in a centrifugally stressed, rotating furnace to within 1 mm of the desired optical figure. Attention is also given to the mechanical design of the active lap.

Angel, J. R. P.↗

NASA NTRS1986

Easily Accessible Camera Mount

Modified mount enables fast alinement of movie cameras in explosionproof housings. Screw on side and readily reached through side door of housing. Mount includes right-angle drive mechanism containing two miter gears that turn threaded shaft. Shaft drives movable dovetail clamping jaw that engages fixed dovetail plate on camera. Mechanism alines camera in housing and secures it. Reduces installation time by 80 percent.

Chalson, H. E.↗

NASA NTRS1986

Manual "Guillotine" Wirecutter

Many wires cut in one operation. Guillotine wirecutter powered by handcrank. Crank turns recirculating-ball screw, which pushes blade through bundle of wires in cutting block. Designed to help astronauts break through spacecraft payload cables while working outside spacecraft. Used on Earth for emergency cable separation or cable trimming in production.

Wedlake, W. J.↗

NASA NTRS1986

Jig for Removing Rivets

Drill-press jig used to remove improperly installed rivets. Drillpress jig makes possible to drill accurately-centered, straight holes through rivets. Key component of jig is a drill bushing with spherical recess machined into base. Contour of recess matches contour of rivet head. Operator holds jig handle with one hand and controls drill with other. Handle and screw head hold drill bit in place over center of rivet so rivet drilled out through its axis. With rivet removed, parts separated and refastened or reused elsewhere.

Roebuck, T. P.↗

NASA NTRS1986

Adjustable Headband for Earphones

New handband designed for comfort and convenience. New band consists of pair of steel head-clamping spring strips joined by tensioning screw. Cushioned side support mounted on end of one strip, and cushioned earphone and microphone mounted on end of second strip. Band reversible. Easily adjusted for head size and readily readjusted for greater comfort without removing.

Toole, P. C.↗

NASA NTRS1986

Low-Flammability PTFE for High-Oxygen Environments

Modified forming process removes volatile combustible materials. Flammability of cable-wrapping tape reduced by altering tape-manufacturing process. In new manufacturing process, tape formed by proprietary process of screw extrusion, followed by washing in solvent and drying. Tape then wrapped as before. Spectrogram taken after extrusion, washing, and drying shows lower hydrocarbon content. PTFE formed by new process suited to oxygen-rich environments. Safe in liquid oxygen of Space Shuttle tank and in medical uses; thin-wall shrinkable tubing in hospital test equipment, surgical instruments, and implants.

Walle, E.↗

NASA NTRS1986

Vortex conception of rotor and mutual effect of screw/propellers

A vortex theory of screw/propellers with variable circulation according to the blade and its azimuth is proposed, the problem is formulated and circulation is expanded in a Fourier series. Equations are given for inductive velocities in space for crews, including those with an infinitely large number of blades and expansion of the inductive velocity by blade azimuth of a second screw. Multiparameter improper integrals are given as a combination of elliptical integrals and elementary functions, and it is shown how to reduce elliptical integrals of the third kind with a complex parameter to integrals with a real parameter.

Lepilkin, A. M.↗

NASA NTRS1985

Continuous inline blending of antimisting kerosene

A continuous inline blender was developed to blend polymer slurries with a stream of jet A fuel. The viscosity of the slurries ranged widely. The key element of the blender was a static mixer placed immediately downstream of the slurry injection point. A positive displacement gear pump for jet A was employed, and a progressive cavity rotary screw pump was used for slurry pumping. Turbine flow meters were employed for jet A metering while the slurry flow rate was calibrated against the pressure drop in the injection tube. While using one of the FM-9 variant slurries, a provision was made for a time delay between the addition of slurry and the addition of amine sequentially into the jet A stream.

Parikh, P.↗

NASA NTRS1987

Grips for Lightweight Tensile Specimens

Set of grips developed for tensile testing of lightweight composite materials. Double-wedge design substantially increases gripping force and reduces slippage. Specimen held by grips made of hardened wedges. Assembly screwed into load cell in tensile-testing machine.

Witte, William G., Jr.↗

NASA NTRS1987

Preset Electrodes for Electrical-Discharge Machining

New electrode holder for electrical-discharge machining (EDM) provides for repeatable loading and setting of many electrodes. New holder is rotating-index tool carrying six, eight, or more electrodes. Before use, all electrodes set with aid of ring surrounding tool, and locked in position with screws. When electrode replaced, EDM operator pulls spring-loaded pin on tool so it rotates about center pin. Fresh electrode then rotated into position against workpiece.

Coker, Bill E.↗

NASA NTRS1986

Development of Deployable Truss Concept for Space Station

A single-fold, automatically deployable and retractable, square-shaped truss concept that is a candidate for the strongback of NASA's Space Station was developed. Compact stowage within a square-shaped housing is achieved by using folded longerons and telescoping diagonal members. Deployment or retraction is accomplished, bay by bay, in a controlled manner with root strength maintained at all times. Control is accomplished by motor-driven jack-screws operated by a controller. Power, data, and fluid utility lines can be integrated onto trays that unfold with the truss. To verify performance a kinematically representative ground test article version is used.

Greenberg, H. S.↗

NASA NTRS1987

Protein crystal growth in low gravity

The solubility and growth mechanism of canavalin were studied, and the applicability of the Schlieren technique to protein crystal growth was investigated. Canavalin which may be crystallized from a basic solution by the addition of hydrogen (H+) ions was shown to have normal solubility characteristics over the range of temperatures (5 to 25 C) and pH (5 to 7.5) studied. The solubility data combined with growth rate data gathered from the seeded growth of canavalin crystals indicated that the growth mechanism at high supersaturation ratios (>1.28) is screw dislocation like. A Schlieren apparatus was constructed and flow patterns were observed in Rochelle salt (sodium potassium tartrate), lysozyme, and canavalin. The critical parameters were identified as the change in density with concentration (dp/dc) and the change in index of refraction with concentration (dn/dc). Some of these values were measured for the materials listed.

Feigelson, Robert S.↗

NASA NTRS1987

Apparatus and method of capturing an orbiting spacecraft

Apparatus and a method of capturing an orbiting spacecraft by attaching a grapple fixture are discussed. A probe is inserted into an opening, such as a rocket nozzle, in the spacecraft until a stop on the prove mechanism contacts the spacecraft. A lever is actuated releasing a spring loaded rod which moves axially along the probe removing a covering sleeve to expose spring loaded toffle fingers which pivot open engaging the side of the opening. The probe is shortened and tensioned by turning a screw thread, pressing the fingers inside of the opening to compress the spacecraft between the toggle fingers and the stop. A grapple fixture attached to the probe, which is thus secured to the spacecraft, is engaged by appropriate retrieval means such as a remote manipulator arm.

Harwell, William D.↗

NASA NTRS1987

Analysis of structures with rotating, flexible substructures applied to rotorcraft aeroelasticity in GRASP

Application to the General Rotorcraft Aeromechanical Stability Program (GRASP) of new methodology for structural dynamic analysis, including substructuring, frames of reference, nodes, finite elements, and constraints, is discussed. The structure is decomposed into a hierarchy of substructures, and discrete relative motion between substructures is analyzed exactly. The finite element method is used to treat deformation of continua, and the library of finite elements includes a nonlinear beam element incorporating aeroelastic effects. Analytical bases for the aeroelastic beam element and the screw constraint are considered, and the important role of geometric stiffness in the formulation is shown.

Hodges, Dewey H.↗

NASA NTRS1987

The characteristics of gamma-prime dislocation pairs in a nickel-base superalloy

The gamma-prime dislocation pairs of a single crystal nickel-base superalloy, PWA 1480, after tensile and fatigue loading at 650 C are analyzed. The existence and extent of cube cross slip in octahedral slip, and the nature of gamma-prime dislocation pairs in primary cube slip are investigated. It is observed that the PWA 1480 specimens oriented near (001) and (-3 6 10) line directions deform by octahedral slip and specimens oriented near (-1 1 1) and (-2 3 4) lines deform by primary cube slip. It is determined that the overall dislocation distributions are more homogeneous in low cycle fatigue (LCF) loading than in monotonic tensile loading; however, the gamma-prime dislocation pair characteristics are similar for tensile and LCF test specimens. The data reveal that the gamma-prime dislocation pairs of octahedral slip specimens are near-screw and on the cube cross slip plane and for the cube slip specimens, the dislocation pairs are of various characters and on the primary cube slip plane.

Gabb, T. P.↗