I've had two visits from RV-7 builders in the last few weeks - Chris Cox from Vancouver, and Alexandre Menezes from Brazil. Chris also works for Transport Canada, and we met through another TC RV builder. Chris is getting ready to start his electrical system, and is somewhat spooked by it. He was in town for a meeting, so came by to see how not to do an electrical system :). Alex somehow found my web page from Brazil, and stopped by as he is in Ottawa for a few months. He built the first RV-7 in Brazil.

I've been making slow, steady progress the last few weeks. I had fallen off the step in terms of hours spent in the garage, so I've been slowly working the pace back up. I've gotten bogged down in fibreglas work, which I don't enjoy, so that has sapped my motivation. But I am getting closer to the end there, so I think I can see the light at the end of the fibreglas tunnel.

I've crossed a small number of things off the snag list, but I've found many new issues to sort out. In the old days, I would simply add it to the snag list, and forget about it. Now I try to close off issues as soon as I find them.

I decided to start at the tail, and work forward, looking for things that needed doing. The first item that caught my eye was the rudder bottom fairing. I had gotten the main part of it done a long time ago, but I had never finished the little removable part at the front. The fairing comes in one piece, but there is no way to fit it around the rudder horn without cutting it in two pieces. I decided to cut slits in the main part, so it would fit over the rudder horn when pushed forward, and to make the top forward part removable. I even made a neat tab that held the front part in place at the centre. It was a work of art, but my idea for running the nav/strobe light cable didn't work out, so the idea blew up.

I had planned to run the cable up the aft side of the vertical stabilizer spar, then bring it down into the rudder bottom fairing. But there wasn't enough clearance between the front to the rudder bottom fairing and the spar for the cable. So, I needed to cut a large hole in the front of the rudder fairing to run the cable through, which interfered with my nifty locating tab. I hacked the tab off, and found that I didn't really need it.

Here is a view with the rudder pushed hard left. You can see where I had to hack some divots out of the removable part to clear the bolt heads that hold the VS spar to the fuselage.

I ran the nav/strobe cable through the VS spar just below the lower hinge bracket.

I used an Adel clamp on a stand-off to hold the cable in place to the bottom of the rudder. That ensures that it doesn't rub against the top or bottom of the slot in the fibreglas.

Here you can see what the front of the main part of the bottom rudder fairing looks like.

Here is a show showing how the removable part fits. The nav/strobe cable goes through the slot between the two pieces of fibreglas.

Another builder e-mailed to ask my opinion on electric elevator trim wiring:

I have delayed rolling and riveting the leading edge of my left elevator until I come up with a good plan for routing the electrical wires from the motor into the stab. I've seen guys route the wire bundle thru the hole directly behind the motor, but the trim screw drive wants to occupy that same space at times, and seems like a future wear problem to me. I will probably drill another hole close by, (any problems with that?) with a rubber grommet, but were you able to come up with some type of quick disconnect to allow you to take the elevator off without having to cut wires? Any good ideas for a protective shroud to contain the wire bundle as it routes from the elevator to the stab?

I responded: Like you, I didn't want to run the wires through the hole where the trim tab screw moves. That looked like an invitation for trouble. I put another hole with a grommet in the elevator spar a bit further outboard. My plan (not yet achieved, it is just a plan) is to run the wires through the hole in the spar, then run them inboard inside the leading edge, bring them out the inboard end of the elevator leading edge. Then I'll go over the HS rear spar in the area of the fuselage aft deck. I'll probably use stick-on attachment points inside the elevator leading edge to attach the wire bundle to with wire ties. As far as the means to break the wire bundle, I'm still wrestling with that one. At the moment I'm considering two options:

1. Use a D-sub connector, as described by Bob Nuckolls at: http://www.aeroelectric.com/articles/macservo/macservo.html

2. Or, I might just crimp on male and female D-sub pins on each wire pair, and then put heat-sink over them to keep them from pulling apart. I would stagger the break point in each wire so as to avoid having all the joints in the same place, which would make the wire bundle look like a snake that had swallowed a frog. Having the joints staggered would also serve as a natural way to identify which wire went with which.

   I got idea #2 from the Aeroelectric-List:

   "I'd like to pass on a suggestion one of my friends made about wire splices, useful on small wires. Attach the pins for a d-sub connector onto each wire (obviously male on one and female on the wire to be joined.) Then, instead of inserting the pin into a connector, simply slide a piece of heat shrink over the pins and the splice is made. If the part needs to be changed out, just cut off the heat shrink."

   Bob Nuckolls' response was:

   "I've used d-sub pins exactly as you have described. They are an excellent, low volume alternative to butt-splices with the advantages of a knife splice. Obviously, the BIG consideration is controlling installation of the bundle to tightly control and limit TENSION on the wires. But what you propose is quite rational."

Both my solutions involve crimping on D-sub pins, but I needed the D-sub crimp tool for my avionics installs anyway. I bought the one that B&C Specialities sells - $44, but it works great.

Last week I finished triming the counter weights on both elevators. It was quite a labourious process, with a lot of trim and check the balance, as I wanted to be sure to not trim too much.

I dimpled all the holes in tail surface outboard ends, and I countersunk the fibreglas tips to accept the dimples. I've still got a bit of touch up work to do on the empennage tips before riveting them in place.

I was at a big conference for the first three days last week, and was on the road for the last two days, so that ate into my building time.

I temporarily mounted the elevators to check whether the elevator tips matched up with the horizontal stab tips. One is pretty much perfect, and the other elevator tip sticks out ever so slightly past the stab tip, but you can't see it unless you take a straight edge and hold it against them. So I am going to leave it as-is. I put some filler on the rudder tip to make it match the vertical stab tip.

I dimpled the rivet holes on the elevators, and started countersinking the holes in the tips. Then I decided to install the elevator counterweights, as they must be installed before the tips are riveted in place. And the counterweights are too heavy as delivered, so some of the lead must be removed so the elevators balance properly. I needed to shorten the trim tab pushrod and install it, so all the components were in place when I balanced the elevators.

I removed a bunch of lead from the aft end of the outboard counterweight (I'm not done yet, as it is still not quite balance).

I drilled a couple of small holes in the inboard counterweight. I'll paint the aircraft after I am flying, and that will move the CG of the control surfaces to the rear. I'll mix up some lead shot and epoxy and pour it in the holes to restore the balance.

Why must the elevators be balanced you ask? To prevent flutter. Read on for an over-simplified explanation of flutter

This week I finished bonding the reinforcing strips behind the flanges on the empennage tips, and drilled out all the holes to 1/8 inch. Then I realized that the edges of the rudder and elevator skins refused to sit down nicely against the empennage tips. I noted that the flanges were not at the same angle as the skins. The flanges were splayed out a bit, so they rested on the skin only on the very edge of the flange.

I decided to remove a bit of material from the edges of the flanges to make the flange surfaces more closely match the skins. The reinforcing strips and thickened resin that held them in place should provide enough extra strength so that it is safe to remove that material from the edges of the flanges. I messed around trying to sand the flanges by hand, but it took too much care to hold the sanding block at the just the right angle, and to be sure to only sand the flange. I was making very, very slow progress. I finally woke up and clamped a long sanding block to the edge of my work table, so it was at 90 degrees to the table top, and at the right height so only the flanges would be sanded. Then it was a quick job to hold the tips against the sanding block and true them out.

I had to put in four rivets in the outboard elevator ribs - I couldn't figure out how to get at them when I riveted the elevators years ago, and I wasn't brave enough to try some of the ways that other builders had used. Today I tried using a back rivet plate, a thin steel bar laid on top of the rivet tail and a hammer to bash the bar, but I couldn't get the rivet to set no matter how hard I swung the hammer. So, I used the same setup, but I placed a rivet gun with flush rivet set on the steel bar, and managed to set each rivet with a long hard blast of the gun. Three of the four rivets came out looking good, but one of the ones on the bottom of one elevator is sitting a big proud of the skin. I don't know what I did to have such good luck - usually my screw-ups end up on the upper surfaces where everyone can see them.

I put the vertical stab and rudder tips on their respective surfaces at the same time, and was dismayed to note that the VS tip sticks up noticeably higher than the rudder tip. I thought I was finished with the filler on those tips, but that was obviously just a pipe dream. I'll have to reinstall the elevators so I can see if I have a similar issue with them.

A larger version of this picture can be seen in the Construction Photo Gallery.

I ended up taking care of a bunch of household chores the first few days of the week, and then finally got motivated to attack fibreglas late in the week. First it was more filler in the low areas on the empennage tips, then sand most of it off, repeat, etc.

Saturday I finally got the empennage tips (except the rudder bottom) smooth enough that I dared shoot a coat of filler-primer on them. I knew that primer has some magical property that highlights every imperfection in the underlying surface, so I wasn't surprised to find a few pin holes in areas that I thought were perfect. Oh well. But, the tips actually looked better than I had expected they would after that first coat. Saturday night I wet-sanded the filler-primer to get it ready for the next coat.

Today I realized that I really should have bonded in the strips of aluminum that reinforce where the blind rivets attach the fibreglas tips to the tail surfaces. I had forgotten about those. :( And as always, the job takes three times as long as you think it should, and that seems to hold true even if you have already multiplied by three when coming up with your initial estimate. :)

I got the metal strips fabricated, drilled the holes where the rivets will go, and drilled another bunch of holes to help the fibreglas resin bond to the metal strips. I mixed up a small batch of resin with microfibres to bond the strips in place, using cleoces dipped in a bit of oil to hold the strips in place while the fibreglas cures. I only got about 60% of the way through the bonding before the resin started to set, it started to get dark and the mosquitoes arrived, so I stopped for the night. I didn't used to let a few mosquitoes bother me, but this West Nile Virus stuff has me looking at them in a different light.

A larger version of this photo can be seen in the Construction Photo Gallery.

Here are all the tail surfaces, except the left elevator, which was not completed when this picture was taken.

On the left, you see the vertical stabilizer, upside down, with the leading edge to the right.

Next is the horizontal stabilizer, with the leading edge to the right.

Next is the right elevator, with the trailing edge to the left.

At the right is the rudder, with the trailing edge to the left.

Here is the rudder in the jig. The purpose of the jig is to hold everything straight so that the surface will not be built with a twist in it.

The boxes in the background are there because we had a big ice storm in early January 1998. There was so much freezing rain that most of the power lines were down. We were without power for ten days, and the lowest level of the basement started to flood because there was no power for the sump pump. All the boxes had to be moved from to the next level up, the workshop.

Here is the rudder skin, with stiffeners riveted to the left side.

You can see the holes in the right side of the skin where the stiffeners will be riveted.

The rudder has very little internal structure, so the purpose of the stiffeners is to keep the large areas of unsupported skin from vibrating.

The inside of the skin is an olive drab colour because of the anti-corrosion primer.

The rivet gun is sitting on the table in the foreground.

Here is the vertical stabilizer skeleton in the jig with the skins on prior to riveting.

The leading edge of the vertical stabilizer is facing up.

The vertical stabilizer is built the same way as the horizontal stabilizer.