The nose skin has been riveted in place up to but not including the spar flanges here. I’ll cleco on the gussets before mashing those rivets. I also put the bottom of the flap back down on the table and weighted it down to be sure all was flat and square before starting those rivets.

OK. Fast Forward here. I’ve already riveted about half of the rivets on the top side of the flap using the skip riveting method. Now I have turned the flap over to start on the bottom rivets. Again I am using my calibrated beer bottles to support the nose of the flap off of the table (not resting on the clecoes) and have the end of the back ribs supported on top of a straight edge and the ribs held down flat with a board and shot bags. I now have about half of the bottom side rivets set at this point. The whole assembly is very rigid and I’m not too worried about things getting out of whack from now on.

Another view of the inverted flap with straight edge and weights keeping things aligned.

Now I have propped the flap between shot bags upright so I can rivet alternately on both spar flanges. Notice I am leaving the topside gussets unriveted until I fit the flap to the wing.

Well Yahoo!  Two flat and straight Flaps to add to the completed Ailerons. I consider this at least a minor milestone. After months of cutting, routing, lightening, flanging, drilling, deburring, dimpling, washing, scrubbing, alodining, priming,and riveting I have the control surface structures completed as far as I can go until the wings are ready. OK, celebration is over. Time to move along to the wings.