6.36 shield, these methods would not be adequate replacements for external torque; therefore external torque had to be restored to the hull soon after it failed, and some form of action would be imperative within two days. If the precessive torque stopped, the hull would also spring back as the spin axis returned to the "untorqued spin axis" shown in Figure 6.15. However, this effect would be very small; for the case of the .75g pseudogravity hull, the springback angle would be 8.93xl07 radian (.134 millimeter at the tips of the endcaps). Second, the system would waste propellant. To precess the hull at l.99lxl07 radian/sec would require a torque of 5.72xlo 4 kg-m 2 /sec 2 if whull were .2712 rad/sec (.75g pseudogravity) (see Section VI.5.2). If this torque were applied by oxygen resistojet thrusters (Isp 200 sec), 160 meters from the center of mass of the hull, then: 5.72xl0 4 = 3 .S?Sxl02 2 2 (Force applied by thrusters) = ~ kg-m /sec Since (Force applied by thrusters) (Mass flow rate of thrusters) (Isp) (g) then: (Mass flow rate of thrusters) 3.575xl0 2 (200) (9,80665) = .182 kg/sec 5.75xlo 6 kg/sidereal year Such propellant would have to be replaced from external sources. Also, propellant would be required to apply the torque for the up-spin of the hull. The ES group felt that because of this propellant waste, this system was an unlikely candidate.for the later, larger colonies. Therefore, this design might not be an adequate prototype of things to come. VI.5.6: The Slowly Spun Shield Option: If the shield were spun about its axis of symmetry, it would have gyroscopic properties (as
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