I'm designing a single axis PV solar tracker. Square tubing will be the structural member of the axis. U-bolted cross members will support the solar panels. Each section of square tubing will be 10'-0" long between supports. Four cross members and four solar panels will attach to each 10' section. The total weight on each 10' section will be about 175# plus the weight of the square tubing. The apparatus will rotate about the central axis of the square tubing, so the weight will be borne upon the tubing in a number of orientations. The four bearing points of the cross members will be 12" from each end and 12" on either side of center, and each point will bear the same weight ~44#. Can anyone help me calculate the size and gauge of the square tubing in steel or aluminum. The cross pieces will be aluminum and the u-bolts will be stainless, so aluminum tubing seems preferable. I hope the square tubing can be either 1.5" OD or at most, 2.0" OD. Can someone help me figure the size and thickness of tubing needed?