Well, it's done finally! The empennage that is.
It's been a few months since I made a log entry. Life has been busy and I haven't had a lot of time to work on the finishing bits for the rest of the empennage. But finally it's all done minus the fiberglass tips which I will save for later in the build. The prices of epoxy are stupid expensive and the stuff has a limited shelf life so mostly for economical reasons, better to do most of it in one batch later in the build.
When I last left off I had completed the final parts for the trim tab installation. With that finished, the remaining tasks were to test install the elevators, trim the horizontal stab skins where required and drill the hole in the elevator control horns that allows them to be joined together. Nothing too hard but the task of drilling the hole in the elevator horns has a lot of 'nightmares' associated with builders who managed to dork it up and had to remove the control horns and have them welded closed again. I didn't want to be one of those people so I spent time researching best how to do this before committing to the task.
First task was to install the elevators to check range of motion. With the rod end bearings set to the correct depth, installing the elevators was actually not that easy to do by myself. The flexible bearings were just a hair larger than the brackets they fit into which meant they never wanted to seat themselves naturally and all of them needed some help getting into position. I eventually learned to use a tool to pry them open slightly (more like just put a little opening pressure on them) which helped the bearings fall into place much easier. So once you install each elevator, you immediately see where the skin from the HS needs to be trimmed on the upper portion to allow the elevator horns to move freely. The plans call for a min of 1/8" clearance for each horn which just requires you to trace out the little area that needs to be removed and cut it off with something like a Dremmel tool. File and debur the freshly cut surface and round the corners and that little task is finished.
With the elevators able to move freely now, time to check the up and down range of motion to make sure the rolled leading edges don't interfere with anything and to make sure you have plenty of up and down travel. I took a hint from another builder and put masking tape on the rolled leading edges to help protect them since they would be getting installed and removed a bunch during this process.
Again taking another hint from other builders, I purchased a set of temporary control hinge pins from Aircraft Spruce that made installing the elevators MUCH, MUCH easier. See the picture below. The threaded handles can be screwed on and off as needed, well worth the money as having to use the actual AN3 bolts each time would have been very difficult, especially by myself.
I played around with a few of the fiberglass tips to see what all was involved in installing these. They would all need trimmed to fit and then cleco'd in place before attaching them. The fiberglass work would add weeks to where I'm already at and I want to move on so ultimately and after purchasing everything but the actual epoxy, I decided to just wait and do all the fiberglass work at a later date and time. The epoxy is very expensive these days (what isn't?) and has a limited shelf life. I would certainly end up wasting a lot of it by just doing the tips of the empennage now. So that can wait as the instructions indicate. Also allows me to take another class or two on fiberglass before diving into that.
Skipping the tips allowed me to proceed to the final steps of the empennage which were to align the elevators and drill the bolt hole into the control horns. This is where I came to a stop for a while as I contemplated why my two elevators did not match up with the control horns clamped in place. The instructions have you clamp the control horns so that the elevators sit in the natural trail position. Doing so resulted in one elevator sitting about 1/2" higher than the other at the outboard tip. I had a few panicky moments but after a lot of research I learned that this is not uncommon, that you can induce some twist into your elevators during construction and ultimately, if it is an issue during your test flights, the twist can be worked out if needed. So I decided ultimately to just press on and I will deal with it down the road. I'm learning that the parts will almost never be completely 100% true and straight (just like the walls in your home) and almost anything can be addressed or fixed if needed.
So now began the process of figuring our how to drill this mythical hole in the elevator horns using a bushing placed through the center bearing. There are lots of methods and opinions out there on how best to accomplish this. Ultimately I used the Van's recommended method of sourcing a bushing from the aviation aisle of the local home store. The AN4 bolt, 4 meaning 4/16" or 1/4" should mean that a bushing with an outside diameter of 1/4" should slide right in there. Ahhhh.....kids this is what they don't tell you in the instructions, go get your 1/4" bushing from the home store and when you get it back to your build shop, use a set of calipers to measure the outside diameter of your newly acquired bushing, then measure the outside diameter of your AN4 bolt. Remember AN4 means 4/16" right so 1/4" right??? In theory they should be the same size. And actually measured in fractional inches, they are the same size. However measure again if you can with your calipers in millimeters and you will see the problem with this. The AN4 bolt is smaller in OD in mm than the bushing you just bought. So when you try to fit this bushing into the bearing to use a drill guide, SURPRISE, it won't fit, it's too big in diameter. So back to the internet and again borrowing an idea from another builder, there is a solution. First of all I purchased both 1/4" plastic and aluminum bushings from the home store. Neither of which fit. Then based on a tip on VAF, I special ordered steel bushings from McMaster-Carr that had an inside diameter that fit a #40 drill bit perfectly. The problem with all of these 1/4" bushings is that they were all too big in OD to fit into that center bearing. So again thanks to a tip I read on another builder's log (thank you Michael Foss), I placed the steel bushing into the chuck of my drill press and tried to sand the OD down to the correct size to fit the center bearing. Unfortunately I wasn't getting anywhere with the steel bushing so I tried the plastic one and that wasn't a great success either. Finally I tried the last one I had, a 1/4" aluminum bushing and I was able to use a combination of a file and sandpaper to mill it down to the correct size so that it would fit into that center bearing. Whew.... that actually worked!
With the bushing issue resolved, it was time to drill that hole. First things first, again through my research it is fairly common for the trailing edges of the elevators to not align perfectly with one another when the control horns are placed in the trail position. If yours do, consider yourself lucky. What you need to be aware of and what the plans don't stress is that it is more important for the trailing edges to be aligned than the control horns or the counterweight horns with the HS skin. Yes of course if one counterweight horn sticks way up into the airflow, that's not good, time to call Van's. But a small amount is considered normal and not an issue. Also it seems rare that the two inboard control horns match perfectly. Knowing that, I figured out which elevator was the true'est of the two and clamped that one into the trail position. In this case the right elevator was the better one and I simply matched the left elevator to the right size using a few pieces of L channel clamped to each elevator surface. To make absolutely sure the elevators were in line with one another I spent a considerable amount of time clamping the L channel and using multiple levels to get them as close as possible. To make a long story short, I clamped one L channel to the top of the elevators and one to the bottom thereby squeezing the two elevators in between the two pieces of L channel. Each L channel had a level zip tied to it and using the level bubbles for each, I was able to find the matching position for the left elevator that made it mirror the right elevator. The result was that the left elevator horn sat a little below the in trail position with the HS skin but just barely and something I can live with.
With the elevators rigged identically to one another, it was time to use that little bushing for what it was intended for. The first step is to remove one of the elevators to give yourself enough room to drill the pilot hole. So off came the left elevator (remember the whole assembly is sitting upside down, so left is right in the pictures). The bushing that I was ultimately able to mill down to size had a larger inside diameter than Van's wants you to use but it's what I had that was the right size and through some test fitting, a #19 drill bit was the matching size for the ID of this little bushing. So I lucked out here because I would have had to order one if I didn't already have it on hand. Time to make a hole in the steel control horn. I knew it would take a while to drill it out as the powder coating is tough enough to drill through on its own. So patiently and carefully I began drilling using the bushing placed through the center bearing as a drill guile. The bushing was snugged up against the control horn and was long enough to make for a very accurate guide. The bushing began spinning right away with the drill bit as the fit of the #19 drill bit was very tight so I had to use a pair of pliers to hold the bushing with one hand and hold the drill in the other. After a few breaks I finally was able to break through and get the pilot hole drilled. At this point I removed the right elevator and put it back into my stand, then used a #12 drill bit followed by a #10 drill bit and finally a 1/4" reamer to make the final sized hole. The reamer is critical here to getting a smooth and precise hole so that the bolt will fit properly. I needed to debur the hole on the outboard side to remove some metal debris. I couldn't get a normal deburring tool in that tight space so I just used the cutting head of a deburring tool and twisted it a few times with my fingers until the hole cleaned up. Right side finished.
On to the left. Again in order to get the hole accurately drilled, I had to put both elevators back on and once again using the L channels and levels, match the elevator trailing edges up. Then I needed to fix the left elevator in that position to drill the hole on that side control horn. Using a combination of scrap wood, weights and wedges, I was able to fix that elevator into position and again using the bushing as a drill guide, drill the initial pilot hole for that side. Then repeat the process, remove the elevator placing it into the stand, then enlarge the hole in steps finally finishing with the 1/4" reamer.
With both bolt holes now drilled into the control horns, one final fit check was needed to make sure everything was good. Off and on the elevators went trying to get all the hardware installed. This time around I actually used the AN3 bolts for the rod end bearings to attach the elevators and struggled a little bit to get the bolts in place. With those in place, I used the AN4 bolt called for with the appropriate washers and some general hardware 1/4" washers as the spacers in between the inboard side of the control horns and the actual center bearing itself. Again this was just to test range of motion and it will all come back apart so I wasn't too technical with the nuts and bolts.
After getting all the hardware installed, that was it. I had a working elevator system. Left and right elevators joined together for the very first time in all these years and it was cool to see how smoothly they moved. Now the bolts holding the elevators in place are not secured with their nuts yet and I understand that once they are, that nice smooth motion can disappear and there can be some very fine adjustments needed for the rigging. But again that is way down the line at this point when the HS and elevators get attached to the fuselage once that has been completed and ready to accept them. So no worries for now, I'll just enjoy getting to this step finally. Here's the dumb part though. After all that, after all the careful measurments and leveling, after all the fretting and worrying, once you bolt the two control horns together, if the bolt isn't very tight (as I have it) you can actually move either elevator independently of the other and not even disturb the opposite side elevator. So as it turns out, I probably way overthought this step and will need to worry about the rigging of the elevators way down the road when the tail gets mated to the fuselage. Oh well, live and learn and move on.
From here, I will need to wait for the tech counselor to stop by to have a final look at the work before I put it in storage for who knows how many years. Once he gives his blessing, I will disassemble everything and put them on shelves in the garage and start on the wings.
During the last two months I also managed a few other projects. One of them was to build new shelves in our basement to hold all of the wing parts. So that took the better part of this past week and they turned out great. I should be able to use them for the fuselage kit parts as well. Just to build the new shelves I had to organize our basement and move a bunch of stuff around first.
I also made one of those METAR maps using a kit I purchased online. So that was a little side project that took a few weeks to build off and on.
The build time on the empennage (minus the fiberglass work) was 4 years and 1 month and according to this EAA log, 442 hours. Not proud of that. Some guys build it in a few months. But doing the math, working 40 hours a week hypothetically, that's 11 weeks to complete so actually right in line with what it should take hours wise. I'm not one of those guys who has the time to do this full time. Instead I'm a full time husband, father, foster parent, professional pilot and active EAA chapter member among other things. I build when my time allows and life gets in the way quite often. When I began this build in May of 2019, no one had ever heard of COVID and I had a different flying job that had me in the airplane or office 4-5 days a week. Things have changed A LOT since then. I now have a better schedule with more time off and we're past the pandemic so I should have more build time. Going forward on the wings, I need to be better at making steady progress. My style would best be summed up as "fits and starts". I'd rather it be steady progress. We'll see.
Looming in the not to distant future are two fuel tanks that need to be built. Let the stress begin! :0