Before trimming we drill a hole in the corner, because snipping into a corner will result in crackling. By drilling a hole, we prevent stress in the Aluminum. Now we can use the left and right snips to trim the Horizontal Stabilizer.

On both sides we had the “First time right”. The Elevators fitted perfectly in the trimmed Horizontal Stabilizer.

After fastening the hinges and drilling the center hinge holes in the Elevator holes, we could finally attach the Elevators to the Horizontal Stabilizer. Look at the size of this part.

So after 129 hours the Empennage is finished. That is to say, I didn’t do the fairings of the Rudder and the Elevators, but as mentioned before, I’ll pick this up as I do the fairings of the Wings.

Time: 4 Hours, Rivets: 0/0

Video

There is one particular rivet (in the corner of the ribs and the spar) that needs to be longer, because it has extra material to go through. During my rivet check, I found I used the too short 4/16″ while it needed to be the 5/16″. If I had used the Go-NoGo gauge, it would be a NoGo, which would have saved me the burden of drilling it out.

Again I needed to drill out and reset several rivets, but this time I know the cause. There are a few rivets with different lengths and in that case I also need to adjust the squeezer, which I tend to forget.
On the aft side of the left Elevator there is a small spar to attach the piano hinge for the Trim Tab. I was certain that I could rivet those with normal rivets, although the plans called out for blind rivets. Again the plans were right, there is just not enough space to rivet them.

With the “standard” (most convenient) yoke you cannot rivet in tight spaces (trailing edges). Hence I switched to my 4″ yoke which only has a rivet set on one side and the other side is not that thick. Now I can set a few more rivets.

Unfortunately the last rivet on either side is still not possible with the squeezer. If I remember correctly I used a barn-door-hinge when riveting the rudder trailing edge. I’ll have to check my blog to see what I did there. I know the result was good.
Almost done with the Elevators, ETA on the Wings is early February, so most likely I will have some idle time.

Time: 4 Hours, Rivets: 297/5

Video

The drawings call out for blind rivets, however I think I can manage to rivet them with “normal” flush rivets.
Bending the trailing edge requires considerable pressure. It’s important to bend it just enough. If you bend it too little, the edge will be concave. If you bend it too much it will turn out concave.

The intended result is that the trailing edge of the Elevator is exactly straight. Measuring it with a ruler, there should be no light between the ruler and the trailing edge. The control surfaces of the plane do not have a wing profile, they are completely straight.

while attaching the skin to the right Elevator I found a piece of Styrofoam still being in between the stiffeners. This time we could laugh about it, after riveting the skin to the understructure, it would not be as amusing.

Although I still don’t have the new piano hinge, I use tho old one (the one I screwed up) to fit the trim tab. The sides of the trim tab fit nice into the left Elevator.
Here we are drilling the piano hinge to the left Elevator.

Now we can fit the connecting rod from the servo motor to the trim tab. One of the NVAV members warned me that the distance between the servo motor and the brackets was too small for the rivets to set. He used washers between the servo motor and the brackets. I’ve decided to counter sink those two rivets instead of dimpling them. This worked great (thanks Victor).

We tested the servo motor and it works great. Next time I can start riveting the skins to the understructure.

Time: 4 Hours, Rivets: 18/0

Video

Unfortunately I couldn’t use the squeezer for the Tip rib and the Counter weight rib, because it has flanges on both sides.
Something clearly is wrong here. I didn’t hold the bucking bar right on this one.

Rivets that are not set correctly need to be drilled out and reset. I keep this “score” in the right side bar. You can see the number of set rivets and reset rivets (after drilling out). Today was a bad day for this particular statistic, because over 10% of my rivets needed resetting (probably my worst score until now).

I could use the squeezer on the spar, but again a lot of rivets didn’t pass my QA. I’m not sure what the reason was, but in the end it got better

Here is a close-up of the result with the reinforcement plate and the plate nut. This platenut will hold the thread of the hinge attaching the Elevator to the Horizontal Stabilizer.

The side rib needs to be riveted with flush rivets, because the control horn goes over these rivets. This horn (the white part in the picture) is attached to the push rod attached to the control stick in the cockpit. This way you can turn the Elevators and let the plane climb or descend.

Here is the right Elevator with the attached control horn.

Next up, bending the trailing edges of the Elevators and, attaching the skin to understructure and finish the trim tab.

Time: 5 Hours, Rivets: 108/13

Video

Easy things first, riveting the stiffeners to the right Elevator. Just as with the Rudder, I use a little structural epoxy at the ends of the stiffeners, to reduce vibrations. This time with back riveting I accidentally riveted next to the back rivet plate in the MDF (three times). Fortunately this only ruins the MDF plate and probably the rivet, but I threw it away just to be sure.

In order to rivet the end of the stiffener at the trailing edge of the Elevator, you have to both press the stiffener and bend (open) the pre-bend skin. This feels scary, but it is ok. I applied some duct tape to the top of my rivet gun to prevent scratching the inside prime job.

After back riveting all stiffeners of both the right and left Elevator, I also back riveted the Trim tab reinforcement plate to left Elevator. I’m not sure how it happened, but I managed to screw up two rivets, so I had to drill them out and reset them. I’m getting better and better in drilling out rivets (not sure if that is good or bad).

I also screwed up the first rivet of the first stiffener, because I had issues with bending the skin. So in total three rivet reset.

We had a lot of snow today and I had to shovel my way out of the workshop. However with the extra heater in the workshop, the temperature was very nice, even though I don’t heat it that much.

Time: 5 Hours, Rivets: 254/3

Video

At this point everything was still ok, but after trimming…

I trimmed the end of the piano hinge the wrong way, sigh. I realized it at this point, you can see the cramped muscles in my cheek.

Oh well, it’s just a piano hinge (and 1 hour of work), so not to bad for a screw up. However I do need to take a note on ALWAYS mark parts to trim. Sounds so obvious, but over-confidence is a nasty thing that creeps up to you while gaining experience.

Instead of trashing the elevator (my normal reaction when I make a mistake), I could set it aside and start dimpling the elevator skins.

Now, I’m considering that mayby I can work around the problem. Anyway, after priming and assembly, I’ll see how far I get an what the result is just before riveting. The good part is that the piano hinge can be riveted last.

Time: 5 Hours, Rivets: 0/0

Video

Here you can see the construction for the right Elevator. When the understructure is completed, we can cleco the skin to it and start match drillig the skin to the understructure. special care must be taken with the control horn, since you can only match drill it while the skin holds the rib an spar together.
Also, because the trailing edge of the Elevators ar not completely bend by Van’s, you have to be careful while match drilling the rib. The reason why the edge is not completely bend is that you need the space to work.

After drilling both the left and right Elevators, we can disassemble them again and start dimpling the parts. I decided not to dimple everything, because I can do that by myself. But since my dad was here today, I valued discussing the Trim Tab construction over dimpling.

We looked at the placement of the servo motor in the left Elevator and the attachment of the Trim Tab with the piano hinges to that Elevator. An important point is how to prevent the hinge rod from sliding out of the piano hinge in flight. A best practice is bending the (protruding) hinge rod and attach it to a fixed part. However the rod is not long enough to do this. Our solution is going to be, making the rod a few millimeters smaller than the piano hinge and squeeze the ends of the piano hinge so the rod can’t fall out. I’ll probably also dip the end of the piano hinge in epoxy, so it’s sealed.

While determining how the Trim Tab fit the Elevator, I remembered that the sides of the Trim Tab (and one side of the Elevator) need to be bend. That’s why it didn’t fit. Taking these bend lines into account it fitted perfectly.

Time: 4 Hours, Rivets: 0/0

Video