Sonex 1404

As usual, progress has been slow, but for a good reason. Child #2 arrived in July and the months prior to that were a bit hectic. I had my father-in-law to help after that, and I took the chance to complete the wing. As usual, I have left the bottom wing skin unriveted to make the installation of the control rods easier. Here are some pictures.


The DRDT-2 makes dimpling very easy.IMG_0598IMG_0600IMG_0602IMG_0603

Riveted the ribs to the spar.IMG_0604IMG_0605IMG_0606IMG_0608IMG_0609

Installing the tie-down ring.IMG_0610

And the position/strobe lights.IMG_0611

There’s my pregnant wife helping me move the leading edge skin.IMG_0646

More dimpling, the leading edge skin this time.IMG_0654IMG_0655IMG_0659

Using a flexible conduit to run the wires through. I’ll have to do this on the right wing too. The string is left in place to help pull through any new wires or conduits.IMG_0661IMG_0662IMG_0663

I hung the clecoed assembly by the rafters. The idea is to rivet the wing while hanging by the ratchet straps. Once complete, it would be very easy to just tighten the straps and leave the wing right there.IMG_0666IMG_0667IMG_0668IMG_0669

Bottom skin not riveted, but wing is essentially complete.IMG_0672IMG_0673IMG_0674

We have been thinking of moving to our own house, so I built this wing cradle to transport the wings. Can’t trust them to the movers!IMG_0676

I’ll resume the build once we are settled in our new place and I’ve set up the garage. It could be several months before the workshop is ready and the fuselage kit is shipped from Sonex, but I’m busy with two kids now!


I decided to take a slightly different approach to building the left wing. Instead of riveting the ribs to the spar before fitting the skins, I decided to leave all the riveting to the end. This would allow me to dimple the forward ribs using the DRDT-2 instead of the hand dimpler. Here are the photos of the progress to date.

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Once I’m done with fitting the skins, wing-walk doubler and updrilling all holes, I’ll disassemble everything and deburr all holes and skin edges. I also have to install the wing-tip and position lights and draw the wiring through the forward ribs.


Work has been going on in fits and starts, but has been progressing nonetheless. In the last year or so, I have completed the right wing and finished most of the work on the left wing. Here are some photos of the right wing. The bottom aft skin is not riveted yet because I want a lot more room to work with as I install the aileron and flap push-rods.

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I hung the (mostly) completed right wing by the beams in the garage using ratchet straps.

The wing box has to be perfectly level at the root and tip. Also, the aft spar attach point has to be exactly 19″ from a reference point on the main spar to ensure the whole structure is square. I bought two long spirit levels and a right angle from Home Depot to set up the structure for skinning.

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I used several wood pieces to keep the assembly level and square.

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Once everything was square, I clecoed the pre-drilled top aft skin to the rear spar and worked towards the main spar.

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The wing then went back on to the saw horses so I could flip it upside down to attach the bottom aft skin.


I had an EAA Tech Counselor come visit to see my project at this time. Bob Steffen is a serial offender and has built several RVs. He complimented me on my workmanship and gave me several suggestions, chief of which was that I should put wiring into the wing if I planned to install lights in the future. I had planned on Sonex 1404 being a day VFR only airplane, but following his advice, I decided to install wiring and the position lights right now. I went ahead and ordered the AveoFlash Powerburst lights that Sonex recommends, and also the wingtips with the integrated mounts for those lights. I also ordered tubing, snap bushings and wires to run through the wings.

Bob Steffen


I flipped the wing over on my workbench and squared it up again. As with the top aft skin, the bottom aft skin was drilled from back to front.

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The structure went back on the saw horses so I could drill through the spar caps. It is impossible to do that while the wing is on the bench – I am not tall enough! Also, I updrilled half the holes to 1/8″ so I could replenish my stock of silver clecoes.


I got the wing tip lights from Wicks at this time. These are integrated nav, position and strobe lights and are very compact. They also don’t need a light on the tail since both of them have white lights at the rear and these are visible from the back of the airplane with the proper mounts. I enlarged the machining holes on the nose ribs and inserted snap bushings.

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After drilling the holes through the spar caps, I put the wing back on the bench and draped the leading edge skin and clecoed it to the main spar. Unfortunately, the skin bent in the middle while carrying it resulting in a small crease across the leading edge. The pictures don’t show it too well, but it looks worse in person.

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I ordered another skin from Sonex, but proceeded to drill and cleco the leading edge skin with the idea that I would just swap the new skin for the old one. I first inserted the tubing into the rib holes. This will carry the wires for the lights.

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Another view of the crease right in the middle of the picture.


My wife helped with the clecoing while I drilled – makes everything so much faster than doing it alone.

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I turned around the wing and used some ratchet straps to get the holes to line up with the main spar. More drilling and clecoing followed until it was done. I noticed that the crease in the middle didn’t look so bad anymore, probably because the skin is now stretched a little. I decided to cancel the order for a new skin. I’ll see what I can do to remove what’s left of the crease. The options I have are

1. Cut it out and put the landing light in there – I don’t like this option because I want the landing light on the left wing – not the right

2. Leave it as it is

3. Paint the wings and smooth out the crease in that process

I like 2 or 3, but haven’t made up my mind yet.

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I also finished up the “unfinished business” on the ailerons – the two holes that I thought I couldn’t reach. With a combination of force and finesse, and also some luck, I riveted the holes in both the ailerons. The Tech Counselor had said I could go ahead and put a rivet in the middle of those two and ignore the holes, but I am glad I could get this done per plan.

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As it turned out, one of the lights wasn’t working properly. The strobe and position lights don’t work together on the right side light. I sent back the unit to AveoUSA and am waiting for a warranty replacement.

I’ve been working on assembling the right wing over the last few months. Progress has been slow but steady. Here are some pictures.

Fitting the rear spar:



Wing box all riveted:



I had a little issue with the holes in the rib flanges not matching to the ones in the spar web while also ensuring the top and bottom rib flanges aligned with the spar caps. I ended up elongating some holes too much and ordered new ribs. Sonex was nice enough to provide the ribs as warranty replacement because I bought both the ribs and the pre-assembled spar from them, and the problems shouldn’t have happened.

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I am finally getting to assembling the wing structure. At a high level, this includes attaching the ribs to the spars and then skinning the entire wing.

I decided to start with the right wing – no particular reason. I laid the main spar on my work bench and drilled a “pattern” center spacer using the pilot holes on the spar web. I drilled all the spacers under the “pattern” in the drill press. I repeated this for the web spacer and clecoed the center and web spacers plus forward and aft ribs to the main spar.

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This is after all the ribs were clecoed.

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I took the help of my wife to place the assembly over a pair of saw horses so that I could updrill the rib attachment holes in the spar easily.


This is work for the next weekend.


Posted on: July 6, 2013

The last set of control surfaces I had to build were the ailerons. These are slightly more complex than the other surfaces because of the lead counterweight assembly. First step was to assemble the control horns.


Next step was to cut the lead block into shape. I had read that this was a fairly difficult thing to do because of the tendency of the lead to bind to the cutting tool. The trick apparently was to use something with large teeth. I had the perfect tool for that – my wood saw that I used when building the workbenches. It worked beautifully. The cut isn’t very clean, but I’ll beat the rough surface into shape after I have balanced the assembly.


I then built the counterweight assembly which holds the lead weight. This is basically two ribs attached by a bridge which goes into the aileron, while the extended aluminum plates on the other side hold the lead between them.


I drilled all holes in the lead before riveting the assembly together. The easiest way to drill lead is to use the slowest speed with plenty of lubricating oil. You have to give a chance for the drill bit to cut into the lead.


I then riveted the assembly and bolted the counterweight. Little did I know that I had to remove the counterweight at a later point.


I then proceeded to cut the skins to size and make all the notches necessary. The cutting on the outboard edge is a bit tricky because the three points of the triangle are at differing lengths from the inboard edge – no perpendicular cuts there.

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The next few steps were easy – locating the ribs, pilot drilling the holes, and clecoing everything together.

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The outboard tip ribs were part of the kit and one of the edges had to be bent for it to fit into the end. The bending brake proved useful, but I still had to use my hands to get it to bend all the way.


After this, there was a bit of a wrestling match to get the tip rib in properly. I had to fabricate a little tool to help me pull back and hold the rib’s end while I drilled the pilot holes and clecoed them together. You can see the tool sticking out in the middle picture. It came off when I removed everything to clean and deburr.

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I repeated this on both ailerons and then updrilled, deburred and clecoed them altogether again. This is when I found out that I had to remove the counterweights to get access to two holes at the bottom which would have been otherwise impossible to get to.

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I riveted everything together, but still couldn’t get my riveter to pull a rivet from those two holes at the bottom.

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I decided to put the counterweights back on and put this on the list of things to ask my tech counselor. Some people have drilled one hole in the middle and put a rivet in there, but I don’t want to do that before talking to someone knowledgeable. Kerry and Sonex said it should be possible to put rivets into those holes, but I can’t quite figure out how. All my “riveting in hard to reach places” techniques seem to not work here.


I put away the ailerons up in the rafters. I took a trip to India after this. Next step – attach the ribs to the spars!