6.37 described in Appendix VI.Bl. Therefore, like the hull, the shield would require a constant torque to precess it. There is a particular case of interest. If the shield were spun in the opposite direction from the hull at an wshield such that Hshield = Hhull' then the angular momentum vectors ~shield and ~hull would be equal and opposite. Then equal and opposite torques ~shield and ~hull would generate equal rates of precession nshield and nhull in the same direction. Since equal and opposite torques could be given to shield and hull by reacting one against the other, this would offer a wasteless method to precess both hull and shield the necessary revolution per sidereal year. An estimate of I , the moment of inertia of the shield zshield about its axis of symmetry, appears in Appendix VI.C.3. The shield's angular momentum is given by: (8.73xl012 kg-m2)wshield To precess the shield once around per sidereal year would require a torque: I (1. 99lxl0-? rad/sec) zshieldwshield An estimate of I , the moment of inertia of the shield Yshield about a transverse axis, appears in Appendix VI.C.4. Th~ angular deflection of the shield spin axis around the torque axis would be: 0 steady stateshield ( 1y shield) (Lshield) (Hshield) 2 (1. 26xlo 13J (1. 74xl0 6 ) (7.62xl025)wshield (2.87xl07 sec- 1 ) wshield
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