2.3 Hours -
On a project like this, one thing you quickly learn is that you need the right tool for the job. When I get stuck, I look at other people’s build sites to see how they got through it. Generally, I’m stuck in the same place that many others have had trouble, and, generally, someone has figured out an easy way to get it done. Trying to fit the elevators to the horizontal stabilizer demonstrated this.
The elevators attach to the horizontal stabilizer using two bolts that pass through a hinge (attached to the horizontal stabilizer) and a rod end bearing (attached to the elevator). This sounds simple, but there is relatively little space to maneuver the bolt. On my first attempt to attach the elevators, I could not figure out any way to do this. A needle nose pliers was too large, and I even tried to make a special tool out of scrap aluminum that would hold the bolt while I tried to steer it into place. I quickly gave up figuring that there had to be a better way.
Searching builder’s sites, it appeared that the tool of choice was a pair of curved forceps. The cheapest one I could find was from Avery Tools. Of course, while I was on the Avery website, I found other stuff to buy. My forceps order also included a tube of inspection lacquer (torque seal) and a set of temporary assembly pins. The pins are used instead of bolts during the initial fitting…more on this later. I placed my order from Avery’s on Sunday and it arrived on Tuesday…awesome service.
Temporary assembly pins and a pair of curved forceps are a must for fitting control surfaces.
Using a combination of the assembly pins and forceps, it was easy to attach the elevators. Once attached, I could see how much of the horizontal stabilizer’s skin would need to be removed in order to allow the elevators to rotate freely. Not wanting to take too much, I would attach the elevator, mark, remove elevator, cut, reattach, mark, etc., until the fit was perfect. In the end, it took about three cycles of attaching and removing each elevator before I was happy. To make the cuts, I used a Dremel with a cutoff wheel. To finish the edges, I used a combination of a Dremel with a sanding drum and some emery cloth.
Temporary assembly pins from Avery made fitting the elevators much simpler than on my prior attempts.
The left elevator is temporarily attached to the horizontal stabilizer. Some of the horizontal stabilizer has to be trimmed away in order to properly fit the elevator.
Just a bit more needs to be trimmed away for proper fit of the right elevator.
With both elevators attached, I was able to do a preliminary check on their range of travel. Downward travel was severely limited by the horizontal stabilizer’s rear spar flange. Some builders wait to cut this flange until everything is attached to the fuselage, but most builders go ahead and make the cut now. I chose to make the cut now as it was obvious that the elevator travel was nowhere near the required amount. To make the cut, I just marked where the elevator horns contacted the flange and cut away the material almost to the rear spar reinforcement bars. The plans are very clear that you do not want nick these bars. As with the previous cuts, I used a Dremel to make the cut and some emery cloth to fine tune the edges. A bit more material may need to be removed in the end, but I’ll wait until it is attached to the fuselage to cut away any more. If I could do this again, I would make the cut before the horizontal stabilizer is assembled.
Both elevators have been temporarily attached to the horizontal stabilizer.
Some of the horizontal stabilizer rear spar will need to be trimmed away to allow the elevator horns to reach their full down position.
The completed horizontal stabilizer rear spar cut-out for the elevator horns.
Finally, I did a little bit of electrical work on the trim servo. I’m going to wire the servo with a D-sub connector as demonstrated at aeroelectric.com. While i won’t attach the actual connector yet, I went ahead and crimped male d-sub pins to all the wires coming out of the servo. This will make them easier to work with in the future. To crimp the pins, I used a 4-indent crimp tool and closed barrel machined pins. I covered the crimps with a piece of 1/16” heat shrink tubing in order to give them some protection.
A close up of the crimps on a couple of male d-sub pins.
Bottom left: a male d-sub connector. Top right: the pieces of wire resulting from my first attempt with the d-sub pins.
Once crimped, a piece of heat shrink tubing seals the exposed areas and protects the crimps from vibration.
