[chaster]

Originally Posted by aerohead

I'd be inclined to gang them close together,consolidating them into a single 'structure.' Seems like all the moments would be reduced to the minimum given any load,so all the stresses would also be minimized.
One frontal area at Cd 1.11 vs many smaller frontal areas at Cd 1.11,with complete flow separation for both configurations.I suspect that the gaps wouldn't relieve the drag as they'd already be embedded in the separated wake of each panel whose interference drag might escalate the drag over the single structure.
As a guess,you could design for perpendicular flow.

( 1/2 )(0.00237)(1.11)(frontal area)( anticipated worst gust velocity-squared) = Force resolved at center of heliostat.
Your mount, standpipe ,and concrete footing would be required to stand up to that loading.
I wouldn't worry about lift. As others have mentioned,it will be the delta-P across the front/back of the unit which develops the load.
Also,make sure the mount is very strong,as at times there will probably be a Karman vortex street developed behind the heliostat,and this cyclic vortex shedding will want to shake your work apart.

Good points. The question in my mind is the magnitude of the interference drag..