6.7 There were complications with shape 2. First, the ES group could not devise a simple, safe method to move cargo in and out of a spinning hull except along the spin axis. To do this, the torus would require a central section with a cargo hatch and a path from this central section to the torus proper. Figure 6.3 shows such a design. Shape 1, however, would not be seriously affected by the problem since it could have a cargo hatch on its spin axis without needing an extra section. As stated in Section VI.3.2, it was expected that most of the construction materials would be processed, manufactured, and assembled at LS. The ES group felt that the torus with center section and hollow spokes was a complicated shape which might be difficult to fabricate and assemble. The cross sections depicted in Figure 6.4 also showed that shape 1 made more efficient use of its hull area than shape 2. The ES group decided to use shape 1. VI.3.5: Dimensions of Hull: To sum up, the ES group was designing a small, cylindrical colony which could spin up to 3 RPM to provide a pseudogravity between .Sg and lg. The relationship between radius of gyration and spin rate is plotted for pseudogravities of .Sg, .75g, and l.0g in Figure 6.5. Centrifugal acceleration (pseudogravity) is a function of a radius of gyration and angular velocity: (Centrifugal acceleration) = Rw 2 where, if centrifugal acceleration has units m/sec 2 , w is angular velocity in radians/second, and R is the radius of gyration in meters. w is related to revolutions per minute by: (RPM) (2rr) w = 60 The smallest radius which allows a lg environment without exceeding 3 RPM is 100 meters. This radius, at 2.2 RPM, provides .Sg; at 2.6 RPM, .75g; at 3 RPM, lg. This would be suitable for long-term medical experiments to investigate the effects of these ranges of pseudogravity and RPM if the colony could be spun at different rates during its time of operation.
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