Longitudinal girder loads were computed and plotted for orbital transfer and attitude control thrust conditions. Figure 7-14 shows the results plotted against longitudinal distance from center. Also shown is the limit load capability of a girder sized for stiffness. When utilizing the thrusters for the orbital transfer (LEO to GEO) propulsion, it now becomes evident that location of these thrusters at the extreme geometric distances from the center of gravity of the satellite will produce the worst case structure design. The preferred location of the orbital transfer propulsion would be near the center of the configuration. The attitude control girder load shown occurs when opposing endmounted attitude control thruster groups fire in opposite directions. All loads shown are assumed for static load conditions and are averaged across the structure width. Figure 7-14. Longitudinal girder load distribution for orbit transfer and attitude control thrust. In summary, it has been shown that the photovoltaic structural requirements can be met with a basic solar array structure consisting of large triangular truss girders ranging in length to 433 m with shear stiffeners provided by cross-bracing cables. The truss girders are fabricated from smaller triangular beams which have V-hat section longerons and channel section lateral members. Truss girders are also stiffened by cross-bracing cables. Height
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