I realized the plans don’t have a step for riveting the final outboard holes in the rear spar, so I went ahead and riveted them.
Then I set the trailing edge up for riveting by cleaning the wedges, applying double sided tape, and locating them on the bottom skin. I used a couple of channels to keep the trailing edge straight while the tape cures overnight.
Today I squeezed all the forward spar flange-to-skin rivets, and the outboard rib flange rivets. Also riveted the skin to counter-weight skin rivets.
Starting with the left elevator, I squeezed the rivets in the spar flange, where the clecos are showing in this picture.
Then the left outboard rib flanges, except the aft 4 rivets, as these will be set once the trailing edge is done.
Then it was a repeat on the right elevator. Everything went well, and I’m now ready to tackle the trailing edges for both elevators.
Over the last couple of days I’ve been working on riveting the inboard ends of the elevators.
Mostly it has been fine, but a couple of rivets have been frustrating.
The left elevator has a flange on the aft end of the inboard rib. Access to the two rivets is tight, and I struggled to get both of the in. The plans say to use a flush rivet set on the universal rivet heads where access is tight. It’s hard to get a squeezer in there, so I ended up bucking them both. The bucking bar scruffier the tops of the adjacent rivets, which looks ugly, but is not really a problem. I’m going to replace these two rivets on the flange, but decided to move on for now, so I don’t waste too much time here.
Luckily the other rivets have all been much easier to access. The two rivets connecting the gusset and the spar were reachable with the squeezer, and came out great. As did the pop rivets for the trim tab brace.
Then it was on to the inboard rib top and bottom flanges, which went smoothly.
With that done on both elevators, I riveted the left elevator top skin to the forward spar. Here it is flipped over, with the top skin riveted, and the bottom skin ready for skin/spar riveting.
Today I riveted the main elevator spars to the ribs. This was quite easy, as it was pop riveting with easy access.
Here’s the inboard rib connected to the main spar with three pop rivets. Each elevator has 6 ribs.
I used a weighted board to hold the elevator flat while riveting. Despite the precaution, I noticed afterwards that the elevator has a slight bend from one end to the other, perhaps 1/8 of an inch. Not sure if it’ll change once the skin is riveted onto the main spar flange, we shall see.
Last night I finished riveting the ribs together on both elevators. Tonight I made a straight table top to help with steps that require a straight surface.
The rib riveting was less challenging than I thought, and I was able to make some good progress last night. The ribs are in two parts, one part riveted to the each of the skins. Then the two pieces are riveted together. Access to the aft two rivets in each rib is very limited, so a decent amount of time was needed to get each rivet ready to go. In the end it all worked out.
The only issue was an incompletely removed rivet shank, in a place that was very hard to access. I left it in there, as there’s nothing for it to interfere with.
The end result was good, lots of neatly riveted ribs. The front riveted were done with a pneumatic pop riveted, which sped up the whole process.
With those rivets set, I clecoed the front spar assembly to each elevator.
The next few steps include attaching the forward spar, and then riveting the root and tip ribs to the skin, then it’s trailing edge time, servo install, trim tab install, and then rolling the leading edges.
Today I riveted the elevator rear spars to the left bottom, and right top skins, joining the two half’s of each elevator.
Because the rear spar is around 6 inches forward of the trailing edge, access to the rivets is difficult. I bought the long bucking bar, which makes the process very simple. The bar is specifically shaped for this step, and once inserted between the two skins, a little down force on the back of the bar gives plenty of leverage on the back of the rivet (edge of bench is the fulcrum). The elevator is shimmed up to account for the trailing edge break.
The plans suggest starting with the left elevator to get used to the bucking bar on a bottom skin. It turned out to be easy to use. Here’s what it looks like with the bucking bar between the skins.
With the left elevator rivets bucked, I squeezed all the remaining rivets where the trim tab cutout gives access to the spar.
Then a repeat of the process for the right elevator, this time working with the top skin. Everything went well.
Hard to see in the picture, but this is the row of bucked rivets in the right elevator.
Now that these skins are all assembled, it’s much easier to keep everything organized because there are fewer parts. Will be good to get the front spars attached, that will give me even more space to work.
Tomorrow evening I’ll start riveting the ribs together inside the elevators. Access is going to be hard for the rear rivets, so I’m anticipating it may take a couple of sessions to get it done.
After a two week break over Christmas and New Year, I spend a few hours today back-riveting the ribs and elevator trim access doubler, and riveting the right rear spar to one of the skins.
First I back riveted the left elevator ribs to the bottom skin. Here’s a picture of the right elevator at the same stage, which I did later in the day.
Next I riveted the right rear spar to the right elevator bottom skin. This calls for clamping to an edge, then shimming the ribs up so they don’t bend.
Then it was time to rivet the skin to the spar. This went well with no issues. I have a new camera in the garage to capture stills and video, I’m trying it out to see if it’s useful for helping document the build process.
Installing the doubler was a little tricky. I back riveted most of the rivets, but some were in awkward locations, so I squeezed a few. The 3-3.5 rivets are a little long, and a few of my rivets were less than perfect, but nothing I felt was worth removing and redoing.
Then I back riveted ribs to the top skins for both elevators. Here’s a picture of the left elevator tip skin with ribs riveted.
The next step is to join the skins by riveting them to the rear spar, then riveting the ribs together. Then the front spar gets attached, then lots of odd rivets to close out the elevators, then the trailing edge, and finally rolling and riveting the front edges. Feels like the end is in sight for the elevators!
After a quick work trip over the last two days, I was able to complete a couple of steps today. I riveted the left top skin to the rear flange, and finished the trim tab. The trim tab is actually the first piece that I’ve built that is completely finished. All the other parts have Fiberglass fairings to shape before they are ready to fly.
The spar flange rivets were done in two steps. I squeezed the rivets holding the skin and hinge to the spar, then bucked the remaining rivets. I was happy with the results, although I need to touch up some sprint on the rear spar due to bucking bar scratches. I spent some time setting up and clamping the pieces, including shimming the ribs to avoid anything bending.
Then I went back to the trim tab. I started by squeezing the trailing edge rivets slightly, and checking for twist. Then I double-flush riveted the rivets, jumping around to avoid building in a twist. I was happy with the result, but learned a lesson to apply tape to the edge of the back riveting plate. I ended up scuffing the skin slightly, which is a bit annoying. The edges turned out near perfect, straight as an arrow. The foam ribs could have been sanded down slightly, as there is a subtle bulge in the skin in their locations.
With that done, I pop riveted the close out tabs and then stashed this piece in the cupboard.
Tonight I riveted ribs to the rear spars, along with shear clips and a gusset.
Given my experience riveting thin aluminum, and it’s tendency to bend easily, I used some tape to hold down the edges of the ribs to keep them in position. I also shimmed up the spars to get the spar web square to the bench top. Then I used some more shims to support the squeezer so I could keep everything very steady. The results were great, and all but one rivet set perfectly. On one rivet squeeze I slipped and somehow the rib pulled away from the spar slightly, and the rivet head backed off from the spar web. The result was a gap between the manufactured rivet head and the spar web, and another gap between the spar and rib. I carefully drilled out the rivet head, popped out the rivet shank, and replaced it with a new one.
The end result was perfect, and I went to bed happy.
Tonight I riveted on the elevator horns.
This was an easy task, as access was good, and the powder coated steel horns are very rigid. The only issue I had was a minor hole alignment challenge on some of the holes on the right elevator. I ended up reaming a couple of holes where the rivets were slightly too tight. Not enough to be worried about.
I used a squeezer on all rivets, and took time to carefully line up each squeeze so that the squeezer was exactly square, and fully supported. I used a combination of blocks and terry towels to aid in the alignment. I was really happy with how it turned out.
