Time: 6 Hours
The weekend started off right with nice weather although it is warming, finally. I wanted to give the primer on the right elevator substructure parts a little more time to cure since it is pretty humid here. So I started to work on a difficult project (and a tough decision) on the left elevator. As I have discussed in other posts the left elevator differs from the right in that it has a trim tab. For you non flying types, this tab can be adjusted inflight to reduce the loads on the control stick by helping deflect the elevator in the direction needed. So the left elevator has a cut out for this tab that will attach with a hinge. The side view of the tab ends and the one side of the elevator where the cut out is have to be dealt with. Van’s has you use wood wedges to make a form and bend the aluminum over closing up these ends. The usually leads to headaches if the bend doesn’t go smooth and ends up with a dented and mangled end. I have read several blogs and it made me nervous. The other option is to cut off the ends (the ears) and install a riblet to that area. That was my plan, I mentally prepared myself to this process. For now I will work on just the elevator as the trim tab will be done in the following days. I need to make a run to Home Depot to get some new cut off wheels for my Dremal tool. Once I got back from the Depot I needed to lay out the cut line. I found the line where the bend line would have been and marked it out.
After measuring top and bottom 43 times and remarking a few times I was finally satisfied with the location of my mark. So now was the time to make a cut with the Dremal tool. The plan was to cut within a 1/16″ of the line and use a file to bring the cut right to the line.
So what to replace those ears with? Several builders have built their own riblet from scratch aluminum. I don’t have any experience with bending and forming tight spaces yet. So I decided to follow another path and use a piece of a E-703 rib. This is a rib that is used in the elevator so it has the right shape already in it. I ordered two extra ribs when I ordered my other parts, due to my earlier mistake on the counterbalance weight, from Van’s. I had one scrap E-703 so that made up the three I needed, one for the elevator and two for the trim tab. So I did some measuring and came up with the right length. I wanted the riblet to extend into the trim spar and tie them together. The problem with that plan was that the elevator skin was already pre drilled to the trim spar. Where the riblet would land in the trim spar had a drill hole right on top of the riblet web line and not on the middle of the flange where it needed to be. I could slide the riblet inward to accommodate this hole but I wanted the riblet to be flush with the edge of the skin for the strength factor. So I then decided that connecting the riblet to the trim spar wasn’t necessary as the the ears that folded over wouldn’t have either. So I took my measurements and cut the end of the E-703 rib on my band saw and finalized the shape with my Scotch-Brite wheel.
This rib was already matched drilled to the end in the elevator during my counterbalance mistake. So the holes in the end where there already and I would need to do some careful measuring. Normally you would have the holes in the skin and drill the riblet from those holes. This time I would work backwards. I’m happy to say that my measurements were spot on and all matched perfectly.
That was a lot of fun! and it was time for a lunch break to give my brain a rest, it doesn’t take much to wear mine out! :-). After a little food and rest I got back at it. Now up was to rivet the right elevator substructure. The plans call for you to rivet the two ends ribs, E-703 & E-704 together then to the spar. I have read several blogs the recommend you rivet the shorter rib, E-703 to the spar first then to E-704. This is due to the weird angle of those two rivets, so that’s what I did. Then I riveted the two ribs together pretty easily.
The plans give you the option on the next step. There are four rivets, two top and two bottom that attach part of the E-713 strap to the skin that will be inaccessible to buck when the spar is in place. They give you the option to rivet those now with solid rivets or later with blind pop rivets. I decided to go solid and keep the look the same.
Now to place a dab of RTV silicone on the ends of the elevator stiffeners that meet each other at the trailing edge to prevent vibration cracks. Then you slide the counterbalance weight in place followed by the spar substructure. I the clekoed the pieces all together.