Flexural pivots for space applications
Design and fabrication of flexible pivots for aerospace structures
Seelig, F. A.↗
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Flexible pivot mount eliminates friction and hysteresis
Flexible steel pivot mount, suspended by flat vertical beryllium copper springs, is capable of rotation, free of hysteresis and starting friction. Mount requires no lubrication, is made in varying sizes, and is driven with either dc torque motor or mechanical linkage.
Highman, C. O.↗
Analytical and experimental investigation of gas bearing tilting pad pivots Final report
Fretting damage in gas bearing tilting pad pivots
Arwas, E. B.↗
Dynamic behavior of air lubricated pivoted-pad journal bearing-rotor system. 1 - Effects of mount stiffness and damping
Effects of mount stiffness and damping on dynamic behavior of air lubricated pivoted-pad journal bearing-rotor system - Vol. 1
Anderson, W. J.↗
A study to determine the flight characteristics and handling qualities of variable geometry spacecraft. Volume 1 - High L/D concept with single pivot two- position skewed wing
Flight characteristics and handling qualities of high L/D concept with single pivot two position skewed wing spacecraft
Kuchta, B. J.↗
Pivotal shock absorbing pad assembly Patent
Pivotal shock absorbing assembly for use as load distributing portion in landing gear systems of space vehicles
Blumrich, J. F.↗
Development of compressor end seals stator interstage seals, and stator pivot seals in advanced air breathing propulsion systems. Part 2: Experimental data and analysis
Performance tests of compressor seals and stator pivot seals used with air breathing propulsion systems - Part 2
Hawkins, R. M.↗
Performance of gas-lubricated nonconforming pivoted-pad journal bearings and a flexibly mounted spiral-groove thrust bearing
A test program was conducted to determine the performance characteristics of gas-lubricated nonconforming pivoted-pad journal bearings and a spiral-groove thrust bearing designed for the Brayton cycle rotating unit (BRU). Hydrostatic, hybrid (simultaneously hydrostatic and hydrodynamic), and hydrodynamic tests were conducted in argon gas at ambient pressure and temperature ranges representative of hydrostatic operation up to the 10.5-kWe BRU power-generating level. Performance of the gas lubricated bearings is presented, including hydrostatic gas flow rates, bearing clearances, bearing temperatures, and transient performance.
Ream, L. W.↗
Flight experience with a pivoting traversing boundary-layer probe
A pivoting traversing boundary layer probe was evaluated in flight on an F-104 airplane. The evaluation was performed at free stream Mach numbers from 0.8 to 2.0. The unit is described, and operating problems and their solutions are discussed. Conventional boundary layer profiles containing variations in flow angle within the viscous layer are shown for free stream Mach numbers of 0.8, 1.6, and 2.0. Although the unit was not optimized for size and weight, it successfully measured simultaneously flow angularity, probe height, and pitot pressure through the boundary layer.
Montoya, L. C.↗
Compact reliable multiaxis pivot
Triple-axis pivot-arm wrist developed for wrist joint for remote-manipulator arm allows three degrees of freedom in wrist joint. Device also contains power-chain components sufficient for 15 foot/pound torque. Device could be used with prosthetics.
Johnston, J. D.↗
Design charts for arbitrarily pivoted, liquid-lubricated flat-sector-pad thrust bearing
A flat, sector-shaped geometry for a liquid-lubricated thrust bearing is analyzed considering both the pitch and roll of the pad. Results are presented in design charts that enable a direct approach to the design of point- and line-pivoted, tilting pad bearings. A comparison is made with the Mitchell bearing approximation and it is found that this approximation always overestimates load capacity.
Etsion, I.↗
Space Shuttle Solid Rocket booster nozzle flexible seal pivot point dynamics
The NASA Space Shuttle Solid Rocket Motor (SRM) uses an omniaxial flexible seal for vectoring the nozzle. This flexible seal, being built under the technical management of Marshall Space Flight Center in Huntsville, Alabama, is the first ever to be used on a manned spacecraft booster. Since no test history on the particular type of flexible seal being used was available and since flexible seal dynamics characteristics affect many vehicle hardware design and manufacture requirements, a rigorous test program to assess the integrity and operating characteristics of the seal was developed and executed. Vector requirements of the SRM flexible seal and results of subscale and full-scale prototype seal verification tests are included. The advantages of an improved method of calculating actuator stroke versus vector angle and pressure over the more classical method of calculating actuator strokes using pivot point envelopes are discussed. Results presented show that the SRM seal design will satisfy flight requirements.
Gaffin, R. D.↗
Pivoting output unit control systems activated by jacks
An invention to be used for controlling aircraft flaps is described. It is applicable to control systems with two coaxial output units which pivot simultaneously with respect to two fixed units and which are activated by two opposed, straight coaxial jacks.
Belliere, P.↗
The proto-type wrist joint assembly TACPAW (Triple Axis Common Pivot Arm Wrist), phase 2
A wrist joint assembly is described for use with a mechanical manipulator arm for finely positioning an end-effector carried by the wrist joint on the terminal end of the manipulator arm. The wrist joint assembly is pivotable about a first axis to produce a yaw motion, a second axis to produce a pitch motion, and a third axis to produce a roll motion. The performance of the wrist configuration is indicative of the capability to produce the 15 ft lb torque in either one of the three motions and the smoothness of operation is notable.
Kersten, L.↗
Mechanisms of UK radiometers flown on Nimbus 5 and 6 with particular reference to bearings, pivots and lubrication
The mechanisms incorporated in the vertical sounding infrared radiometry experiments which were launched on Nimbus 5 in 1972 and on Nimbus 6 in 1975 are discussed. Both use dry lubricants. The Nimbus 5 radiometer includes a rotating chopper driven via a carbon fiber-acetal resin gearwheel. The driving motor runs at 2000 rpm and has completed over 7 x 10 to the 9th power revolutions. Four gear driven filter wheels powered by stepper motors have each completed 2 x 10 to the 8th power changes. The input calibration mirror mechanism and its field of view compensation mechanisms are also described. All 25 ball races used in the experiment are of the film transfer type. The Nimbus 6 radiometer includes two cells. Each contains a piston supported on diaphragm springs and driven electromagnetically. The pistons are 6 cm in diameter with a stroke of 1 cm and are driven at their mechanical resonant frequency of approx. 15 Hz. The calibrating mirrors rotate periodically to view a target. The support pivots are synthetic sapphire ring stones with separate end thrust stones. The problems of mounting these stones to withstand vibration loads is described.
Hadley, H.↗
Triple-axis common-pivot arm wrist device for manipulative applications
A concept in manipulator development to overcome the 'weak wrist syndrome', a triple-axis common-pivot arm wrist (TACPAW), is presented. It contains torque motors for actuation, tachometers for measuring rate, and resolvers for position measurements. Furthermore, it provides three degrees of freedom, i.e., pitch, yaw, and roll, in a single manipulator joint. The advantages of this development are increased strength, compactness, and simplification of controls. Designed to be compatible with the protoflight manipulator arm, the joints of TACPAW are back-driveable with + or - 45 deg rotation in pitch, + or - 45 deg in yaw and continuous roll in either direction while delivering 20.5 N-m (15 ft-lb) torque in each of the three movements.
Kersten, L.↗
Loss model for off-design performance analysis of radial turbines with pivoting-vane, variable-area stators
An off-design performance loss model is developed for variable-area (pivoted vane) radial turbines. The variation in stator loss with stator area is determined by a viscous loss model while the variation in rotor loss due to stator area variation (for no stator end-clearance gap) is determined through analytical matching of experimental data. An incidence loss model is also based on matching of the experimental data. A stator vane end-clearance leakage model is developed and sample calculations are made to show the predicted effects of stator vane end-clearance leakage on performance.
Meitner, P. L.↗
Off-design performance loss model for radial turbines with pivoting, variable-area stators
An off-design performance loss model was developed for variable stator (pivoted vane), radial turbines through analytical modeling and experimental data analysis. Stator loss is determined by a viscous loss model; stator vane end-clearance leakage effects are determined by a clearance flow model. Rotor loss coefficient were obtained by analyzing the experimental data from a turbine rotor previously tested with six stators having throat areas from 20 to 144 percent of design area and were correlated with stator-to-rotor throat area ratio. An incidence loss model was selected to obtain best agreement with experimental results. Predicted turbine performance is compared with experimental results for the design rotor as well as with results for extended and cutback versions of the rotor. Sample calculations were made to show the effects of stator vane end-clearance leakage.
Meitner, P. L.↗