Next it’s time to set the spar blocks and wash-out spacers in the proper position before anything else is glued. The blocks are positioned flush with the leading edge tube as noted in the manual. My assumption is this sets the proper wash-out spacing along with the ¼” spacer placed under the rear spar (noted on the plans). Next the root rib is glued to the rear spar and leading edge. The wire / rubber-band clamps help keep the leading edge seated nicely.