concept has seven major compression columns. The rectangular shape appears to be more suited to automatic fabrication and assembly in orbit than the diamond shape. Counterweights are used to obtain equal moments of inertia about the three primary axes, like config. 76D-1. This configuration cannot operate as a solar oriented SPS, because the antennas would periodically beam through the corners of the solar array. Figure IV-A-4-5 & 6 (Config. 76K): This configuration is the same as Config. 76J except for different dimensions for the rectangular shape, which are optimized for minimum counterweight to have equal moments of inertia about two axes. Figure IV-A-4-7 (Config. 76L): This configuration is oriented perpendicular to the orbit plane and has a single antenna located between two rectangular arrays. Total power output is one half that of the previously discussed two antenna arrangements. The structure for each array consists of compression columns supported with tension lines. A continuous beam spans the total length, connects the two arrays and provides a support axis for the centrally located antenna. Figure IV-A-4-8 & 9 (Config. 76M & 76N): Configuration 76M and N are oriented perpendicular to the orbit plane and have a single centrally located antenna. The only difference in these two concepts is the detail arrangement of the solar cell/reflector system as illustrated. Neither of these concepts use counterweights, but achieve equal moments of inertia (Ix = Iz) about two axes by arrangement of the structure and array (one half the array area on each side of the neutral axis as illustrated). Figure IV-A-4-10 (Config. 76P): This configuration is oriented perpendicular to the orbit plane and has a single centrally located antenna. Structural rigidity for this concept is achieved through the use of compression columns and tension lines. Counterweights are used to obtain equal moments of inertia about two axes. In this concept the solar cells occupy the central portion of the array and the solar collectors are located on the sides. Figure IV-A-4-11 (Config. 76R): Configuration 76R is oriented perpendicular to the orbit plane and has an antenna located at each end of the structure as illustrated. The structure for this concept is simply a three dimensional rectangular truss system 5 km x 28 km of constant thickness. This concept does not have equal moments of inertia about the mutually orthogonal axes; and, therefore, will require almost continuous reaction control thrust to counteract gravity gradient torques. Of all the configurations, this one seems to be the simplest to fabricate and assemble. It seems quite feasible to construct this configuration efficiently with a single operation output from an automatic machine or factory in orbit. Figure IV-A-4-12 (Config. 76-S): This configuration is similar to 76R except the structural concept is different and would probably be
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