The sphere will be in a Reynolds range of 620k to 1,550k which is well past separation. At 100mph the Cd is about 0.1 and climbs to 0.2 at 200mph. Therefore the drag force for the 8" sphere at 100 would be .88 lbf and at 200 would be 7.12 lbf. The 10" sphere at 100 would be 1.38 lbf and at 200 would be 11.12 lbf. You could drop the Cd substantially through streamlining. The sweet spot for streamlining is a thickness/chord ratio of 0.25...

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