Friction torque of ball bearings with burnished MoS2 films at .1 nanotorr at several loads using five retainer materials
Determination of bearing torque for burnished molybdenum disulfide ball bearings
Anderson, W. J.↗
SEARCH · Engineering Papers
Results for “torque”
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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Bidirectional step torque filter with zero backlash characteristic Patent
Gearing system for eliminating backlash and filtering input torque fluctuations from high inertia load
Baker, R. L.↗
Spacecraft radiation torques - Space vehicle design criteria /guidance and control/
Radiation torque sources and effects on spacecraft and spacecraft attitude control system design
Source record↗
Spacecraft aerodynamic torques - Space vehicle design criteria /guidance and control/
Assessment of disturbance torques due to interaction of spacecraft with atmosphere in long duration orbits for use in design of spacecraft attitude control systems
Source record↗
The Mark 6 torquemeter, an instrument for measuring magnetic torques on spacecraft
Design and circuitry of torquemeter for measuring magnetic torques on spacecraft
Boyle, J. C.↗
Unwanted gimbal rotation torques from gyro spinmotors
Unwanted gimbal rotation friction torques in gyro wheel bearings due to lubrication viscous friction, ball wedging and contamination
Haagens, R. G.↗
Modeling of environmental torques of a spin- stabilized spacecraft in a near-earth orbit
Computerized simulation of disturbance torques of spin stabilized spacecraft in near earth orbit
Tidwell, N. W.↗
The solar radiation pressure force and torques model
Mathematical model of solar radiation pressure force and torque acting on spacecraft surface intercepting solar photon stream
Georgevic, R. M.↗
Noncontact torque measurement using stroboscopic techniques
Noncontact torquemeter measures torsional deflection of rotating shaft and results are viewed on vernier scale. Magnitude of torque must be calculated from measured deflection. Device has no electric connections with the rotating member and is easy to use.
Leonard, W. H.↗
Angular momentum desaturation for Skylab using gravity gradient torques
An angular momentum desaturation method for momentum exchange devices of orbiting spacecraft is described. The specific application of the method is to the Skylab which contains three double-gimbaled control moment gyros for precise attitude control and maneuvering. It is assumed that the attitude reference is inertially fixed and that two of the vehicle principal moments of inertia are much larger than the third. Gravity gradient torques and resultant angular momentum accumulation are developed for small deviations from the reference. The assumed moment-of-inertia distribution allows desaturation about all axes with only two attitude angles each for the two axes with large moments of inertia. The necessary desaturation maneuvers can be decoupled for a special set of orbital coordinates. All maneuvers are made during the night portion of the orbit, and the percentage utilized for desaturation is selectable. Expressions for the attitude angle commands are developed assuming infinite vehicle rates. The effect of finite rates introduces an efficiency into the desaturation. Expressions for this efficiency are developed and means for compensation are treated. Arbitrary misalignments between geometric vehicle axes and principal moment-of-inertia axes are permissible. An angle bias about the sun line minimizes the angular momentum accumulation about the sun line projection into the orbital plane. Adaptive desaturation maneuver limiting consistent with the available maneuver momentum is included.
Kennel, H. F.↗
Nutational stability of a dual-spin satellite under the influence of applied reaction torques
It is assumed that since the solar paddle attachments to the hub of the spacecraft are not rigidly locked, the effect of the solar panels can be replaced by a constant reaction torque acting on the hub of the spacecraft. This could result in the satellite having an equilibrium motion about an axis displaced from the nominal axis of symmetry. The variational equations of motion are developed about such an equilibrium position using the SAS-A spacecraft as a model. Energy dissipation on the rotor as well as the main body is included. This nonautonomous set of differential equations are linearized and transformed to an autonomous set using the Liapunov reducibility theorem. The stability of the kinematically similar system is examined numerically using representative SAS-A parameters for the case when either pair of solar panels is assumed to be loosely attached. Stability is verified for small system nutation angles (0.1 degree).
Bainum, P. M.↗
Thermomagnetic torques in polyatomic gases
The application of the Scott effect to the dynamics of galactic and stellar rotation is investigated. Efforts were also made to improve the sensitivity and stability of torque measurements and understand the microscopic mechanism that causes the Scott effect.
Hildebrandt, A. F.↗
Variable-frequency inverter controls torque, speed, and braking in ac induction motors
Dc to ac inverter provides optimum frequency and voltage to ac induction motor, in response to different motor-load and speed requirements. Inverter varies slip frequency of motor in proportion to required torque. Inverter protects motor from high current surges, controls negative slip to apply braking, and returns energy stored in momentum of load to dc power source.
Nola, F. J.↗
Analysis of the computed torque drive method and comparison with conventional position servo for a computer-controlled manipulator
A manipulator and its control system (modeled after a Stanford design) is being developed as part of an artificial intelligence project. This development includes an analytical study of the control system software. A comparison is presented of the computed torque method and the conventional position servo. No conclusion is made as to the perference of one system over the other, as it is dependent upon the application and the results of a sampled data analysis.
Markiewicz, B. R.↗
Space shuttle GN and C equation document no. 20: Fine alignment gyro torquing angles
The procedure for aligning the inertial reference unit of the space shuttle by celestial references is discussed. The gyro torquing angles required to go from the present stable member to the desired stable member are determined. The inputs are the transformation matrix from the reference to the desired stable member coordinates and the unit vectors to the two target stars in both the reference and present stable member coordinates. The equations involved in establishing the reference are developed.
St.amand, J.↗
An ironless armature brushless torque motor
A high torque motor with improved servo mechanism is reported. Armature windings are cast into an epoxy cylinder and armature conductors are integrally cast with an aluminum mounting ring which provides thermal conductance directly into the structure. This configuration eliminates magnetic hysteresis because there is no relative motion between the rotating magnetic field and any stationary iron. The absence of destabilization forces provides a fast electrical response compared with a typical torquer of conventional construction.
Studer, P. A.↗
A study of numerical methods of solution of the equations of motion of a controlled satellite under the influence of gravity gradient torque
Numerical methods of integration of the equations of motion of a controlled satellite under the influence of gravity-gradient torque are considered. The results of computer experimentation using a number of Runge-Kutta, multi-step, and extrapolation methods for the numerical integration of this differential system are presented, and particularly efficient methods are noted. A large bibliography of numerical methods for initial value problems for ordinary differential equations is presented, and a compilation of Runge-Kutta and multistep formulas is given. Less common numerical integration techniques from the literature are noted for further consideration.
Thompson, J. F.↗
Effects of gravity-gradient torque on the rotational motion of a triaxial satellite in a precessing elliptic orbit.
A method of general perturbations, based on the use of Lie series to generate approximate canonical transformations, is applied to study the effects of gravity-gradient torque on the rotational motion of a triaxial, rigid satellite. The center of mass of the satellite is constrained to move in an elliptic orbit about an attracting point mass. The orbit, which has a constant inclination, is free to precess and spin. The method of general perturbations is used to obtain the Hamiltonian for the nonresonant secular and long-period rotational motion of the satellite. The differential equations derivable from the transformed Hamiltonian are integrable, and the solution for the long-term motion may be expressed in terms of Jacobian elliptic functions and elliptic integrals. Geometrical aspects of the long-term rotational motion are discussed, and a comparison of theoretical results with observations is made.
Cochran, J. E.↗