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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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Aerodynamic and gravity gradient torque effects on attitude control of Apollo/S-4B configuration in circular earth orbit
Spacecraft design considerations associated with disturbance torques caused by mass expulsion
Solar wind-induced torque calculated considering special and general relativistic effects, extending method to pulsar rotational model
Two body torque free gyrostat equations of rotational motion, relating rotational, spin and precession angular velocities
Manual and semiautomatic ultrasonic torque wrenches for tightening flared tubing connections
Determination of bearing torque for burnished molybdenum disulfide ball bearings
Gearing system for eliminating backlash and filtering input torque fluctuations from high inertia load
Radiation torque sources and effects on spacecraft and spacecraft attitude control system design
Assessment of disturbance torques due to interaction of spacecraft with atmosphere in long duration orbits for use in design of spacecraft attitude control systems
Design and circuitry of torquemeter for measuring magnetic torques on spacecraft
Unwanted gimbal rotation friction torques in gyro wheel bearings due to lubrication viscous friction, ball wedging and contamination
Computerized simulation of disturbance torques of spin stabilized spacecraft in near earth orbit
Mathematical model of solar radiation pressure force and torque acting on spacecraft surface intercepting solar photon stream
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.
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.
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).
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.
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.