We are finally ready to begin putting the tail cone together. There are points in the build process when I realize "holy crap, we are building an airplane!" and this is definitely one of those points.
Our first step was to dig the tail cone skins out of storage and peel off the blue vinyl. Rather than just remove the vinyl along the rivet holes, like we did on the vertical and horizontal stabilizer skins, we decided to completely remove the vinyl on the tail cone. There are so many rivet holes in this part of the plane that we would be removing 75% of the vinyl anyway, so we might as well just take it all off. It also means that the tail cone is very shiny and reflective, which makes it harder to take good pictures of some parts of the build.
This is also a great time to admire the sawhorses that Mike built. He debated for a long time about whether or not to buy prebuilt sawhorses or make our own. Ultimately, he decided to build them because the plans suggest using sawhorses that are a couple of inches taller than the standard prebuilt version. These home built sawhorses also have some other benefits that we discovered later on.
This skin is the bottom of the tail cone and once it was ready, we flipped it over so we could start adding the bulkheads. The bulkheads are basically vertical walls that provide structural support. These walls just happen to have large holes in the middle.
There are small notches cut out of the edge of each bulkhead and this is where those J-channel stringers get installed.
There are also some shorter stringers that run inside that bottom skin, but they were really hard to photograph.
Once the stringers are in place, we peeled the vinyl off the side skin and put it into position.
If you want a good arm workout sometime, come help us peel vinyl off these skins! It's hard work and takes much longer than you would expect. You'll also notice that the side skins have a curve in one side. This curve forms that bottom edges of the tail cone. Here's a side view where you can see how the stringers run against the side skin.
This is also where we discovered an added benefit of our home built sawhorses. Once the side skin was in place, one side was much heavier than the other and we were worried that it would fall of the sawhorses. There's an additional structural component at the widest end of the tail cone called the "bellcrank ribs". I have no idea what a "bellcrank" is or why it needs ribs, but their inconvenient locations meant that the sawhorse had to sit about two feet from the end of the tail cone. Because our home built sawhorses are made of standard 2x4's we were able to do this.
Instead of a solid 2x4 across the top of the sawhorse, we used two smaller scrap chunks of lumber and were able to create a gap for those bellcrank ribs.
At this point, I left the hangar for several hours while Mike match drilled holes in all those stringers. I don't know that I've explained match drilling yet - it simply means that there are already holes in one part, in this case the skins, and you need to drill matching holes in some underlying piece, in this case the stringers. Remember those lines we drew down the stringers in my last post? Those lines help Mike make sure that the stringers are in the perfect location when he drills the holes. It took hours for Mike to drill all those holes and when I came back to pick him up, this is what it looked like.
Our final step of the day was to flip the whole thing over...
Next, we will add the other side skin.