I put in a couple of hours tonight deburring parts. Not much to report. It’s a straightforward process, but can be a bit slow going, especially where there are corners. I almost finished deburring the aft three bulkheads, but started falling alseep, so calling it for today. Of course most of these parts will need final drilling and then more deburring, but that is a relatively quick process.
My 3/8 countersink arrived today, so I in stalled it in my modified cage and calibrated it on some scrap. Using the bench press, I countersunk the 8 holes in these two stops.
I’m really happy with how these turned out.
I spent a couple of hours today deburring parts for the aft two bulkheads. I also finished shaping the rudder stops.
Deburring was straightforward, except for the flanges at the bottom on the bulkhead, where there is a very small gap. I picked up some Emory cloth to squeeze in between the tighter spots, otherwise I used files and edge deburring tools. I still need to final drill some of the holes, but I’m waiting on a drill block that will help ensure the holes are exactly perpendicular, since some of them receive fine-tolerance bolts that hold the vertical stabilizer.
Finishing the rudder stops involved some more filing. I clamped my vixen file to the bench and this helped ensure a straight edge.
I also modified a countersink cage to allow me to countersink the rudder stops. There is very little clearance between the flange and the hole. Also on-order is a 3/8 inch countersink bit to allow enough clearance (typically they are 1/2 inch).
I spent a couple of hours this week working on fabricating the horizontal Stabilizer attach bar support angle, and the rudder stops. I used a combination of the band saw, vixen file, and small files to get the shape as close as possible to the drawings. I’m still not completely done, but these are pretty close. The vixen file has been great at getting a nice clean flat surface, it makes the job much easier. Once these are final shape, I need to countersink some of the holes, then they will be ready to be primed.
I spent some time cleaning and reorganizing the garage, including building a couple of storage racks for the elevators. I stored them out of the way and then put some loose zip ties on to keep them from falling off.
Then it was time to start on the aft fuselage, and I was able to complete the first few steps, separating parts and straightening a couple of stiffeners.
Several of these pieces were snipped or hack-sawed into separate pieces, including the plastic rudder cable guides. In the picture you can see the open crate in the background. I’ve been storing the skins and stringers in there for months, and it’s good to start pulling them out.
I trimmed and final drilled a few pieces, and then straightened these doublers. Here you can see the “before and after” where one piece is straightened and one is how it arrived. These bend as a result of the hole punching process. Straightening involves putting them in the vice, putting some tension on the part, then pounding with a rubber mallet. The majority of time is spent fine tuning, and having some patience is important.
I used a 9V battery to test the trim tab servo, and everything worked perfectly.
I also made a new shelf for storing the elevators while I build the tail cone.
https://mytwings.com/wp-content/uploads/2020/02/img_4732.movI received a shipment of electrical supplies today from steinair.com, which enabled me to finish the left elevator. Instead of using a molex connector, I went with Stein’s recommendation on using dsub pins, and heat shrinking the wires. I picked up some crimping tools and a decent wire stripper, along with the dsub pins and some heat shrink.
I crimped the male and female pins, then slipped on the heat shrink, and pushed the pins together
Then slipped the heat shrink over the pins and used a heat gun to shrink the wrap making a nice tight seal.
Then I installed it in the left elevator, using some Velcro to hold the wires securely inside the elevator.
With that done, I hooked up the trim tab, and then installed the counterweights, putting some thread marker to ensure I can tell if the nuts ever back off.
Here’s the finished product:
Today I attached and safety wired the trim tab to the left elevator, trimmed and applied silicone to one of the trim tab molex connectors, and fitted the counterweights.
The trim tab fits perfectly, and the hinge is snug against the rear spar. I safety wired the hinge pin into place. I ended up redoing the safety wire after I took this picture, getting a tighter fit and a few less turns
Next job was to trim the corners off a molex plug, then seal it with silicone. This will be exposed to moisture, so the sealant is important. I bought some electrical-grade silicone sealant to ensure it doesn’t react with the wiring in any way.
Then it was onto the final step in the elevator plans, attaching the counterweights. I drilled out the holes to #12 using my drill press, then deburred the holes. I marked and trimmed the weights using a hacksaw and emery file. This was easier than I anticipated, and I soon had the weights ready to attach.
Starting with the right elevator, I bolted on the weights, then torqued them to 28 inch pounds. I used some thread marker to ensure I can tell if these ever back off. With that, the right elevator is finished!
Installing the left elevator weights was more challenging. After some trial and error, I realized that there is an alignment issue with the holes on the tip ribs. These holes are 0.03 inches too far apart, which is causing the bolts to splay out, and preventing them from being able to attach the inboard weight. I carefully filed the bottom hole to allow the bolt to pass, but ran out of time to secure the weights.
Today I flush riveted the trailing edge of the right elevator, and then rolled and riveted the leading edge.
I used a new tool, the safety-pin angled squeezer dies from Cleveland tools, and squeezed all the right elevator trailing edge rivets. These were partially set previously, and I was really happy with the way the edge came out. It looks perfectly straight, and there is less surface scratching than I was getting with back riveting. I should have bought these earlier, and would recommend them. It’s a shame this is the only place I can use them on the aircraft.
Then I set the aft 3 rivets along each edge of the elevator, too and bottom. The last two on each side are pop riveted because of the lack of clearance.
Then I rolled and riveted the leading edge. Having done the rudder and left elevator, this seemed to be much easier. I used my highly specialized tools from earlier (popsicle stick on a piece of tube) and was able to get good rivets into each hole.
I did make a mistake unfortunately, and placed the bottom skin over the top skin on the very outboard section. This is a bummer, because fixing it will be very hard without making a real mess. I guess this will be a distinguishing feature on my plane. It won’t be very visible to the casual observer.
Last night I rolled and clecoed the left leading edge, and tonight I riveted it together. I also drilled a 1/16 inch hole for safety wiring.
Rolling the skins was generally easier than it was for the rudder. The experience from the rudder helped, and the process went faster. I used a 3/4 inch pipe and duct tape to get a good grip and a nice even bend. Using a couple of pipe wrenches helped, and I was pleased with how it turned out. It’s definitely a non-precision exercise though, and it seems like there should be an easier way.
I made up a couple of tools to assist with the riveting, by attaching some popsicle sticks to lengths of tube and aluminum channel. These were helpful is holding the bottom skin (the inside skin) against the top skin, which forms the outside of the join. Without any pressure from inside, it’s hard to keep the two skins close together when setting the rivets.
I’ll be interested to see how much adjustment will be needed once the elevators attach to the horizontal stab.