Sonex 1404

Archive for the ‘Empennage’ Category

I have been extremely delinquent updating this blog, and slightly less so in progressing with the build. In the last one year or so, I had another build in progress with my wife (my son!) which took up most of my time.

However, I did complete the horizontal stabilizer and elevator in September 2011. The photos are attached.

I also moved to California a few months ago and have a large two-car garage to continue my build! I have ordered the wing kit from Sonex and should get it in a few weeks. In the meantime, I plan to set up my new workshop and maybe polish some of the completed pieces.

Hopefully, the build will progress a lot faster in 2012!


I’ve been very busy at work (like that’s new) so I haven’t been able to update the blog. I have however made some progress on the horizontal stabilizer. I completed the forward spar. I then arranged the spars and ribs and aligned them to be true. Finally, I drilled and clecoed them.

Once this was done, it was time to skin the horizontal stabilizer. I used two heavy boxes of tiles that happened to be lying around to hold the skin down while I drilled and clecoed. I then turned it around and repeated the process on the other side.

Once I finished both sides, I saw that I had drilled too close to the edge of one of the ribs. Some of the holes were not even completely within the rib flange – they were straddling the edge. I decided to make another rib, and as luck would have it, I had a piece of stock that was exactly the same length needed.

You can see where the holes are not aligned on the far side of the flange on the top rib in the photo above. The bottom rib is the new one I made. Once it was done, I fit it in the stabilizer frame and drilled/clecoed it in place. This time around, it was perfect.

After this, I drilled/clecoed the rib ends and then finished up the skins. It now looks like it belongs on an airplane – minus the clecoes.

The fiberglass tips are next, followed by the elevators. The hinges on the stabilizer will have to wait until after the elevators are built. Once all of them are fit together, the whole assembly will be up-drilled, clecoed back and riveted.

I assembled the horizontal stabilizer main spar over the last several weeks. It doesn’t really take that long to do it, but many other things got in the way of finishing it up.

The assembly itself is fairly straightforward. I got a bit confused about the overall length of the spar since in one place on the plans it says 78″ and on the other it says 77 61/64″. I saw that it was different and sent an email to Kerry at Sonex who replied saying that 3/64″ wasn’t big enough to bother, and that the two tip ribs would make up the difference anyway. So after I felt about 3/64″ small, I proceeded to assemble and drill the spar.

I then updrilled to #30.

I then cleaned and deburred all the parts, clecoed them back together and then riveted them.

The outer rivets are very close to the channel side so I had to bend the rivet stems and use my nifty little drilled aluminum piece to rivet them at an angle. Regardless, I still had to drill out four rivets and redo them because they were not set properly. There was also another hole where I lost grip of the assembly on the drill press and the hole became much bigger than #30. I drilled a bigger hole and used a CCP-54 rivet in it instead of a CCP-44 (in the center of the photo below).

In the past one week I completed making all the ribs and other miscellaneous parts for the horizontal stabilizer. I got the bending brake from Harbor Freight and it made the bending very very easy. The bends are also a lot cleaner now compared to the ribs on the vertical stabilizer. Since I have to make two of everything for the horizontal stabilizer, using the bending brake ensured that both of them are identical.

Here are some pics.

I have now completed SNX-T04 and SNX-T06 in the plans. Next I can start putting the horizontal stabilizer spars together.

I got the new clecoes so I completed the final assembly and up drilling of the vertical stabilizer.

There was still the small matter of cutting the new vertical tip and fitting it into place which was by far the most unenjoyable part of the entire build to date. A lot of patience later, this was the end result.

Next step was to remove everything, debur and rivet the frame.

After that, I deburred the skin, applied ACF-50 on it to prevent corrosion (no more priming for me) and riveted it to the frame. My wife helped with removing the clecoes and also with some of the riveting which made it go quickly.

I had drilled three holes on the left side of the rear spar which were slightly off. I had to make those holes bigger and put bigger rivets in them. I got CCP-54 rivets from Wick’s for this (and for future goof-ups like this which is bound to happen). This photo shows the bottom most one.

The final product.

I can now get to the horizontal stabilizer. I have ordered a bending brake from Harbor Freight which should make bending the channel stock ends easier. That should give me a lot cleaner set of bends than the ones I had for the vertical stabilizer.

While I waited for more clecoes, I decided to tackle a project that could be completed quickly. I looked through the plans and as mentioned before, the elevator horn looked easy enough. The ribs were already in the kit and so was the welded horn. All I had to do was to drill and rivet them. Easy right?

Not so much. Some of the rivets were in some tight spots. I had to use a combination of the hand rivet puller and a little aluminum thingy I made with a hole in the middle and an angled surface so that I could pull it while not being perpendicular to the surface. I still had to drill out a few rivets, but thankfully the holes didn’t enlarge too much.

Here are some pics.

With the vertical stabilizer skin clecoed, I thought I’d try fitting the new fiberglass tip between the skin and the frame as the plans showed. I was not able to wrap the skin around with the tip in place, but funnily with the whole thing clecoed in place, I could now get the tip in with not too much trouble.

This meant that I did not need to do any “mods” to attach the tip, which was great. I put the tip in, drilled and clecoed it in place and marked the notch to cut for the rudder.

The only problem I see is that the leading edge skin does not sit flush with the tip.

I’ll have to think of something to fill that up, but otherwise this is one big headache that is gone.

I also decided to start updrilling the holes to 1/8″ at this time. I wanted a break from messing around with the fiberglass tip and this seemed like a relaxing, therapeutic thing to do. Which was all great until I ran out of copper clecoes. Here’s the result as of now.

I ordered some more from the Yard Store, but until then I think I’ll get started with the horizontal stabilizer/elevator. I think I’ll work on the elevator horn today.