Elevators

Today I riveted the left elevator trailing edge. I followed the vans recommendations and did this in two steps; slightly setting the rivets, then coming back and fully setting them. I used a squeezer to apply just enough pressure to get the rivet to grip the skins, then alternated sides and holes, distributing the rivet squeezing across the holes. This helps keep the trailing edge straight. Once done, I checked it for straightness, then set up my back-riveting plate. I used a long 8 foot length of steel, and set it up on several blocks of wood. I taped the trailing edge to the back riveting plate, and clamped the plate to my workbench. It’s not great since it’s not an angle, and so it sags and bends if not supported. Since the left edge is short, I wasn’t too worried. I also tried to prevent scratching by putting a thin piece of masking tape along the very edge of the back riveting plate. Setting the rivets was easy, and it worked out, but I did some some abrasions on the trailing edge top skin, which is annoying. I also realized that my trailing edge breaks are excessive, and I shouldn’t have used as much pressure as I did.

Here’s a picture right before back riveting. At this stage all the trailing edge rivets have been partially squeezed.

Tonight I riveted together the servo and the cover plate. The cover plate screws into the bottom of the left elevator, attaching to the plate nuts on the reinforcement plate. The servo is attached to the cover by two C channels, which sit on either side of the servo and orient it correctly. This was a quick and easy step, except for the countersinking of the plate. I spent some time enduring I had my countersink set correctly, because the plate is right at the minimum thickness for countersinking. I’m fairly happy with the way it came out, although one of the rivets is sitting very slightly proud of the plate. I’m not sure why that happened, but it’s not an issue.

With that done, I went ahead and removed the backing on the elevator trailing edges, and set weighted boards on each. Letting this bind overnight will help ensure the edge stays straight. I’m using a shelving support C channel from Home Depot to keep the edges straight. This channel has holes that are perfect for clecoing, and allow you to keep a very straight edge, while the tape’s glue sets overnight. I also added a weighted board to hold it down flat.

While the tank sealant cures, I worked on the next few steps. I shaped the hinge pin by bending according to the specs. It took a few bends before I had a shape that works satisfactory. I definitely need some more practice bending these things.

Then I counter sink and dimpled the trim tab servo attach plate. This plate is attached by screws to the left elevator. On the top of the plate sits the trim tab servo, which is riveted to the plate. I should be able to finish up this piece over the weekend. It’s interesting to finally get into some wiring and electronics for a change.

Tonight I glued in the foam ribs on both elevators. I mixed up a batch of tank sealant, then applied with a gun and a popsicle stick, getting a smooth even coating. I started with the left elevator, then the right, and then weighed down the top skins to ensure the skin stays in contact with the ribs while the sealant cures. I’ll let these sit until the weekend, then can start riveting the trailing edges.

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.