Flap drilling continued
September 19, 2011 – Now that the main structure of the flaps (ribs, skins and hinges) are drilled, it’s time to move on to other parts of the flaps. The spar where the hinge attaches gets countersunk. I removed the bottom skins and left the hinges in place to add as a guide for the pilot of the countersink.
I’m debating whether I want to countersink the top side of the spar. The plans call for dimpling, but I think the spar is too thick for that. I’ll have to do a little more research on that, plus I, like many other people before me, dimpled the flap brace that’s attached to the wing. It is NOT supposed to be, so I may add a doubler to that when I attach the hinge to the wing. That comes later on, though.
There is an angle and a bent doubler attached to the inboard rib of each flap. This is where the flap control rod attaches. I cut the angles to size and laid out the fastener pattern per the plans.
When I had one drilled to #40 holes, I clamped the two together, since they are identical left and right, and drilled the other one.
I clamped the angle in place on the spar, using a drawn center line as a guide, piloted the holes in the spar to #40, then took the holes up to the required #30 (1/8″).
I bent the control rod doublers to the approximate 6.3 degrees that Van’s calls for, then clamped it in place and back-drilled to the rib and the angle.
The aft-most hole in the apex of the doubler aligns with a hole in the rib. That hole gets taken up to 1/4″. This is where the control rod rod end attaches. I used 2 core drills to take the hole up from 1/8″ to 1/4″. I prefer core drills and reamers for larger holes because they make a much cleaner hole than a regular drill bit.
After all this was done, I took everything apart for dimpling and prepping for paint. Part of this process is the usual labeling of parts using wire and aluminum tape, and removing the blue film from the rivet holes on the skins.