Translational forces on the Mariner V spacecraft stemming from the attitude control system

of active damping is that the gyro always damps in with the same side up, and it probably would be best to omit fine damping and depend on either calibrating out the gyro marking error, using stutter shutdown, reducing the hemispherictorquing moments at the end of the damping time so that the spin-axis is driven toward the maximum axis more than toward the effective pole of the markings, or using magnetic damping in connection with hemispheric torquing. Without fine damping, the complexity of the associated electronics for damping would be greatly reduced, because a sizable fraction of the electronics used in this experiment is already included in an ESG for initial spin-up and for spin-axis readout.Details of the Mariner attitude control system limit cycle operation during cruise are presented. Limit cycle operation is shown to vary from the ideal case to single side operation. The data are analyzed to determine the form of the variation and to seek an explanation. The results show that there is a bias torque of several dyne-cm which changes at the end of a limit cycle, coinciding with the firing of an attitude control jet. Diagrams illustrate the various limit-cycle operations and the changes encountered. Because Mariner V had a balanced sun profile, the solar bias was low and it appeared that much of the disturbance torque was self-generated. An analysis of the attitude control jets demonstrated that a sizable torque could be generated by leakage through the attitude control valves. Experimental data obtained confirmed this suspicion. Nomencl atureA = nozzle throat area F = force (thrust) G = gravitational acceleration I sp = specific impulse of jet k = Boltzman constant I = jet couple length m = mass of molecule M = mass flow rate n = molecules number density n v = molecular number density having a velocity, v . t Doctoral candidate. N = molecular number rate P = pressure T = temperature v,v = molecular velocity and average molecular velocity V = gas volumetric flow rate X = mean free path length p -gas density B = angle between nozzle centerline and molecular velocity vector \l/ = nozzle expansion half angle a-= molecular collision cross section T = attitude control torque = momentum of molecule Subscripts 0 = all molecules 1 = molecules that do not impact nozzle 2 = molecule that impacts nozzle s = gas supply conditions

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“…-cos 3^) (15) F = -l -£p s V s (kT/2.55m)^(l + cos 2^ -cos 3 The specific impulse of a jet is defined as…”

Section: Leak Rate Scc/h N0mentioning

confidence: 99%