The corrugated aluminum aileron construction process appears at first pretty straightforward to someone familiar with sheet metal construction. I thought I was but subsequently schooled on some of the nuances unique to this type of build. Others have come to grief building multiple twisted and unusable sets along with all the usual possible missteps involved trying to build a left and right and an upper and lower of anything. This is one way to do it.
I attempted to enumerate each step I followed in producing a flat aileron, but it wound up being two and a half pages of single-spaced text. Even then, as a comprehensive list didn't include many cleanup or turnover steps necessary.
I thought instead I would include here sort of the framework of the fabrication process followed by the assembly framework. Both are separate and distinct processes. (And it will be a lot shorter to read, hopefully making more sense instead of getting caught up in the nuances)
The first of a couple concepts is a corrugated 0.025" sheet of aluminum laying flat on the bench in front of you no longer acts like a flat sheet of aluminum. It's best considered an accordian. The edges will flex around, accordian like unless captured and attached to something that won't. Hence, the need for insert strips along the trailing edges. If the top and bottom skins are attached to the spar but not attached at the trailing edge, you can slide the two trailing edges past one another inducing enormous amounts of twist into the panel. This should be noted when it comes time to drill and attach the trailing edges.
A useful aspect is the top of the aileron is flat. As much drilling and riveting as possible should be accomplished with the top on a flat surface (inverted).
The drilling process follows a slightly different process from riveting due to access limitations to buck/drive the rivets.
I began by fabricating the spar and ribs with the trailing edge pieces set aside for later. Next, I cut the topskin to final size using the template and measurements taken from the respective wing. Since the top is flat, drilling the spar to it while it is inverted on the bench begins the skinning process. After the spar is drilled, drill the trailing edges and inserts, clecoing them to the jig board. After disassembly, backdrill the hinge half to the upper spar flange holes. Mark the hinge for trimming at the outboard end as hinge eyes will not extend the full length of the aileron.
A note about the trailing edge inserts: It's a lot of busy work to produce the elements for the trailing edge insert pieces. There's a curved piece separate from the straight piece which has an angle bent into it and a tapered "hardwood" piece that nests into the bent angle. None of which has thickness dimensions, only the angle dimensions are specified... There is I believe a better way. Vans Aircraft uses a trailing edge wedge in many of their designs control surface trailing edges. It's called "AEX Wedge" and comes in three different lengths that I could find: 20, 51 and 82.5 inches. I discovered this a little too late to backtrack, but if I were to do it again I would seriously consider this stuff to simplify the trailing edge process.
The bottom skin is smaller, but is purposely cut a bit oversize and laid over the inverted panel. The raised beads in the panels need to align with one another, so sliding them to and fro until a satisfactory alignment is achieved, then driling and clecoing them together on the straight portion of the trailing edge only. But since you can't see thru the oversize bottom skin, that step needs to be done with the panel flopped over on the jig or otherwise clamped flat with the topskin (final size) accessible for back drilling to the bottom.
Full disclosure: I bought a set of corrugated aileron skins from Mr. Tom Brown in Wisconsin, just to cut my losses early instead of trying to stamp out the skins on my own... because I know me. They were worth the money. Very nicely, uniformly stamped and in great condition. All the beaded ends along the trailing edges mostly matched until I got to the last aileron. The two skins on that last one would not line up, they were uniform but just enough different spacing that they were going to look awful along the trailing edges where the beaded ends meet. These skins were uniformly stamped, but got rolled and stuffed in a box to get shipped. The inner skins in the roll got rolled a little tighter than the outer ones and sort of took a set. The bottom skin that looked to need a bit of stretching also really had a curl to it, so I rolled it opposite to the set it already had. That stretched it, and it began to get closer to the upper skin. A little more working it with opposite rolling and the two skins matched perfectly.
Next, put the panel back on the bench topside down and drill the bottom skin to the spar short of the tapered portion. When you flex the skin over the tapered spar, it changes dimensionally enough you need to pay attention to the trailing edge ensuring the raised beads remain aligned. Here's where being oversized helps out. The extra edge margin allows you to flex as necessary keeping the trailing edges aligned without running an edge off the spar flange.
I should mention I used small 9-lb sandbags to apply clamping pressures to these skins while doing this. Easier to reposition everything as necessary and less fiddly than spring clamps or otherwise.
Completing drilling the skins together, I used another 3/4" piece of MDF cut about 3/4" undersize around the perimeter of the panel. With the panel bagged down flat on the undersized board, allows access from below for drilling or clecos. The curved portion of the panel/board can then be flexed/aligned, bagged flat and accessed from below to drill and cleco together. Finally, the skin is drilled to the tapered portion of the spar.
The trailing edge inserts get installed and backdrilled through the bottom skin.
Rivet holes for the internal ribs are located and drilled in the skins, then reassembled and backdrilled through to the rib flanges. Similarly, the slots in the skins necessary for the steel actuator tabs are located once the rib positions are finalized, then cut and cleaned up.
Assembly starts after edge trimming the lower skin, deburring everything and, if desired, notching and crimping the bead ends on both skin panels.
Ribs, tabs and spars are first riveted together. The bottom skin gets riveted along the spar initially. Finish up the bottom skin riveting by riveting the ribs to the skin.
The top skin riveting begins by clecoing the inboard end as far as the first internal rib. Then rolling/peeling the skin back to allow access to buck the rib rivets from the inside and rivet gun access from the outside. once riveted, continue by clecoing to the next rib and repeating the process.
Once the ribs are riveted, invert the panel on the undersized jig board, bag and fully cleco in place including the trailing edge inserts and hinge half along the leading edge.
Keeping everything sandbagged flat, continue riveting both leading and trailing edges together. It should be flat.
The above process took me about 50 hours to complete an individual panel.