be enlarged to achieve the desired performance. For example, for the ‘bow-tie' configuration, a view factor of 40% was calculated between (single side) SDRs. This translates to an approximate 20% increase in surface area to compensate for performance loss. In the case of the ‘butterfly' configuration, there is a lower view factor between adjacent modules, but there is also an increase view factor between SDR panels within each SDPM. The addition of radiative area to compensate for view factor imposes a mass penalty for both the ‘bow-tie' and ‘butterfly' design which is proportional to the view factor value. The performance penalty due to adverse SDR view factors in the growth configuration of the Space Station Freedom can be offset by revising the fluid flow path through the SDR. In the baseline configuration, the SDR tubing is arranged in a parallel flow distribution form, as shown in Fig. 4. An alternative parallel-series-parallel (PSP) loop fluid flow arrangement, also depicted in Fig. 4, provides additional heat rejection by doubling the fluid mass flow rate in each tube. Thermal analysis of the parallel and PSP flow arrangements was done to assess thermal performance. The conclusion was that the view factor penalties for the ‘bow-tie' and ‘butterfly' configurations were offset by the enhanced convective heat transfer, and that the thermal performance of all three SDR configurations were comparable. Drag In low earth orbits, such as the one in which the Space Station Freedom will travel, atmospheric particles are encountered that create drag forces acting on the vehicle as it moves around the earth. Atmospheric drag influences the space station life cycle cost in two ways. First, greater drag requires additional reboost fuel mass. Secondly, it raises the minimum required space station orbit height and thus increases the servicing cost. It is therefore desirable to design the space station so that the smallest cross sectional areas are found perpendicular to the flight direction. The size and orientation
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