The occasional pointing errors have been observed for the antenna despin type communications satellites. The mechanism and cause of these errors have been made clear. The main cause of this misbehavior is the sporadic earth sensor noise. This paper also describes the methods to prevent the pointing error from occurring when the sporadic large earth sensor noise occurs.
This paper gives a survey result on the mechanism of quadrature spring rate occurring at the Tuned Dry Gyro. It is noted that the quadrature spring rate is a damping torque. This damping torque is similar to the spring reaction torque generated by the flexure displacement angles and drives the gyro rotor back to a balanced position. In order to investigate the mechanism of damping occurring at the gyro rotor, the relation between surrounding gas pressure and damping factor under gyro nonoperating was measured. Furthermore, the drag torque acting on the gyro rotor was measured by the back EMF method at different surrounding gas pressure. As a result of these testings, it was found out that the quadrature spring rate was generated by gas movement of the flexure around and drag forces due to bearing loss and windage loss, and the mechanism and magnitude of each damping torques which are contributor to the quadrature spring rate were extracted separately.
A method is presented for calculating the flowfield about a cascade of arbitrary two-dimensional blades. A conformal transformation is used to generate a finite-difference grid. Implicit approximate factorization (AF) scheme is used for the solution of matrix equations resulting from finite-difference approximation to the full potential equation in conservation form. For transonic flows, an artificial viscosity, required to maintain stability in supersonic regions, is introduced by an upwind bias of the density. This allows the simple matrix form of the schevie to be retained over the entire flowfield. Supercritical test cases are considered. Blade Mach number or pressure distributions have been computed and are in good agreement with independent results.
During the dynamic motion of ACV, the flow rate of the jet varies and the total pressure at the outlet of the fan changes with the flow rate. Moreover, the flow in the duct is unsteady, so the difference of pressure on both sides of the duct is different from the one of the steady flow condition. Dynamic motions of ACV are induced by oscillations of the ground board and they are analyzed numerically. Taking account of the characteristics of the fan and the duct, the dynamic motions are investigated and the results are compared with those obtained under the condition of the constant total pressure of the jet.
Discharge plasmas in magnetic cusp ion thrusters were studied. To evaluate ion loss rates to the chamber wall, ion density distributions were measured by a Langmuir probe scanned along the wall surface. Comparisons of discharge perfomances were made for various electrode geometries, anode configurations and two different magnetic field strengths. A simple discharge plasma model based on the assumption of ionization by primary electrons was applied to investigate the cusp confinement for the wall and ring anode configurations.