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Rotating fluid coupler, consisting of rotor and housing made of aluminum, that is concentric with electrical slip-ring assembly, transfers cooling fluid to instrumentation undergoing environmental tests on rotating platform. Rotating fluid coupler permits unlimited platform revolutions and eliminates danger of lines being pulled loose from supplies.
Freeze casting of metal ceramic and refractory compound powders into plastic slips
Development of liquid metal slip ring to transfer power between rotating satellite parts
Effect of velocity slip at porous boundary on performance of incompressible porous bearing
Development of slip ring assembly with inner and outer peripheral surfaces used as electrical contacts for brushes
Magnetic head/tape interface problems of satellite data storage tape recording systems, and minimizing stick-slip phenomena
Synergistic effects of slip ring-brush design and fabrication for vacuum application determined by friction, wear, electrical noise, and dielectric strength data
Slip vs static error offset for first and passive second order phase locked loop as function of signal to noise ratio via computer simulation
Slip line deformation of ordered and disordered Cu-Au intermetallic single crystals from microstrain and electron micrographic studies
The design, fabrication, and testing of four power slip rings for synchronous orbit application are considered. Environmental and instrumentation systems necessary for monitoring electrical noise, friction, and brush wear in air and at less than 5 X 10 to the minus 8th power torr were developed. Composite brushes consisting of silver-molybdenum disulfide-graphite and silver-niobium diselenide-graphite were employed on rings of coin silver and rhodium plate. These four contact combinations were tested during ambient condition run-in at 150 and a humidity sequence at 0.1. The first nine months of a two year vacuum test performed at 0.1 rpm were completed.
A program is being conducted for testing of slip rings for synchronous orbit application. Instrumentation systems necessary for monitoring electrical noise, friction, and brush wear at atmospheric pressure and at less than 50 ntorr have been developed. A multiplex scheme necessary for the simultaneous recording of brush displacement, friction, and electrical noise has also been developed. Composite brushes consisting of silver-molybdenum disulfide-graphite and silver-niobium diselenide-graphite have been employed on rings of coin silver and rhodium plate. Four contact combinations have been tested during an ambient condition run-in at 150 rpm and a humidity sequence at 0.1 rpm. The first six months of the two year vacuum test at 0.1 rpm have been completed. Electrical noise, friction and brush wear data recorded during these periods have been analyzed.
A program is being conducted for testing of slip rings for synchronous orbit application. Instrumentation systems necessary for monitoring electrical noise, friction, and brush wear at atmospheric pressure and at less than 50 nanotorr have been developed. A multiplex scheme necessary for the simultaneous recording of brush displacement, friction, and electrical noise has also been developed. Composite brushes consisting of silver-molybdenum disulfide-graphite and silver-niobium diselenide-graphite have been employed on rings of coin silver and rhodium plate. Brush property measurements made included measurement of density, electrical resistivity, shear strength, and microstructure.
Boundary equations obtained for a low Reynolds number, high enthalpy gas flow in regions of velocity slip and temperature jump are presented. The formulation treats, through a first-order distribution function used to include multicomponent diffusion, a multicomponent gas mixture that may be in nonequilibrium with finite-rate catalytic recombination occurring on the wall. In the boundary equations, which are obtained for use in flow-field calculations applicable to low-density flow regimes, a simplified gas/wall interaction is assumed wherein individual atoms or molecules either reflect specularly off the wall or stick and are fully accommodated. Fluxes in terms of evaluated integrals over the distribution function and integrals necessary for determining fluxes are given.
Eight slip ring capsules, each having 80 or 100 circuits, were operated for time periods ranging from 14,300 hours to 24,700 hours. The test mode simulated the motion of gimbal axes of the Saturn inertial guidance the platform in an organic free nitrogen environment. Computer-compiled noise data (approximately 45,000 recordings) were graphed as a function of test time and position within the capsules and as extreme probability distributions. Greater than ninety-nine percent of the noise measurements for the capsules with sufficient lubrication were less than 10 milliohms. Capsules with glass dielectrics did not perform significantly differently than those with filled epoxy dielectrics. The initial wear mode of prow formation was followed by rider wear. After 10 to the 8th power wipes, ring wear depth did not exceed the surface finish and the radial rider wear depth was less than 13 microns.
Measurements of low-density dissociated arc-heated flows around low and high surface catalycity spheres are compared with numerical solutions to the full Navier-Stokes equations for reacting gas flow fields, taking into account slip and finite surface catalytic boundary conditions. A time-dependent finite difference solution technique developed by Li (1973, 1974) is used in the investigation and a simple transport model is employed for the flows considered. The correctness of the solution approach is demonstrated by the very good agreement obtained between experimental and computational data.
The slip conditions for a multicomponent mixture with diffusion, wall-catalyzed atom recombination and thermal radiation are derived, and simplified expressions for engineering applications are presented. The gas mixture may be in chemical nonequilibrium with finite-rate catalytic recombination occurring on the wall. These boundary conditions, which are used for rarefied flow regime flow field calculations, are shown to be necessary for accurate predictions of skin friction and heat transfer coefficients in the rarefied portion of the space shuttle trajectory.
A wire-comb technique is described for transversely grooving the surface of a freshly laid (plastic state) slip-formed concrete overlay installed at Patrick Henry Airport. This method of surface texturing yields better water drainage and pavement skid resistance than that obtained with an older conventional burlap drag concrete surface treatment installed on an adjacent portion of the runway.
An experimental investigation was conducted at the Langley aircraft landing loads and traction facility to study the braking and cornering response of a slip ratio controlled aircraft antiskid braking system with ground speed reference derived from an unbraked nose wheel. The investigation, conducted on dry and wet runway surfaces, utilized one main gear wheel, brake, and tire assembly of a DC-9 series 10 airplane. During maximum braking, the average ratio of the drag force friction coefficient developed by the antiskid system to the maximum drag force friction coefficient available was higher on the dry surface than on damp and flooded surfaces, and was reduced with lighter vertical loads, higher yaw angles, and when new tire treads were replaced by worn treads. Similarly, the average ratio of side force friction coefficient developed by the tire under antiskid control to the maximum side force friction coefficient available to a freely rolling yawed tire decreased with increasing yaw angle, generally increased with ground speed, and decreased when tires with new treads were replaced by those with worn treads.