• Materials - Materials considered for further analysis during the study were anodized aluminim and graphite composites. The latter appears to be a promising choice for the antenna structure due to its lower thermal expansion and high stiffness/density ratio. • Element Member Shape - Two structural shapes were considered in the weight analysis, namely thin walled tube and a triangular hat section. The triangular hat section, although heavier than the tube, has considerably smaller thermal gradients across the section and is therefore a more desirable section. • Type of Construction - Two methods of structural arrangement have been compared on a weight basis; rectangular grid and a radial grid. The results showed that the rectangular grid has a 25% weight advantage over the radial design. • Manufacturing Tolerances - The wall thickness tolerances on standard commercially available tubes are ±10%. A + 10% tolerance on tube weight would increase the antenna structured weight by 13,600 Kg (30000 lb). • Antenna and Antenna Bay Size - During Task 1 of this study, antenna sizing relationships were established to aid in selecting major antenna dimensions. Figure 3.2-19 shows the result of these studies using early configurations. The trends are valid for the final reported configuration weight. • Antenna Mass Properties - Figure 3.2-20 gives the weight, center of gravity, and moments of inertia of the SSPS antenna. The moments about the antenna center of gravity and about the azimuth yoke pivot are given for a total SSPS antenna weight of 1.67 x 106 kg. 3.2.5.4 Antenna Structural Weight Derivation The antenna structural weights were derived using the results of preliminary load, thermal, and stress analyses together with "Structural Arrangement for the MPTS Antenna" (DWG No. MPTS-001). Individual members were sized using a weight optimization technique which equates the Euler column buckling stress to the local buckling stress and the applied stress. The sections resulting from this analysis will be optimum for given material properties, section shape loading requirements and end fixity requirements. Figure 3.2-21 summarizes the weight, dimensions and quantities of the elements and beams which make up the structure of the SSPS antenna. Included are weight estimates of the antenna azimuth and
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