December 2016
With all the components of the Aft Fuselage completed, it is now time to assemble all the pieces together. This step is not required to be completed at this time and could be completed during final assembly. However, since I have all the components handy and still familiar with each one, I thought it would be a good time to complete this step.
The first part of the empennage attach involves attaching the elevators to the horizontal stab. This step involves instilling the rod end bearings to the elevator and adjusting them to get he proper clearance form the horizontal stab. I spent a little bit of time on this step. Initially, I was getting a little bit of rubbing of the rolled forward skin of the elevator and the horizontal stab. The skin was rubbing on a couple of the hinges on the horizontal stab where the rod end bearings attach. The easy fix is to just "screw out" the rod end bearings a little to achieve a little more clearance. However, I wanted to be careful here because I wanted to make sure that I had enough threads in the nut plates that the rod end bearings attach. One thing that can be helpful during adjustment is that because there are two rod end bearings on the elevator, adjusting one in or out will cause the elevator to pivot off the other rod end bearing. With that in mind, you are likely able to adjust the rod end bearing on the opposite side of the rubbing skin IN just a bit which should open up the clearance on the opposite end bearing. Additionally, there is a measurement in the plans of 1 5/8" minimum distance required between the horizontal stab rear spar and the elevator torque tube that has to be maintained during your rod end bearing adjustments. For this measurement, I used a couple of small pieces of wood that I cut that could easily be placed between the HS rear spar and the elevator torque tube to quickly measure and maintain this spacing.
In the end, to get the elevators mounted and spaced properly, I used a combination of slightly modifying the rolled edges of the elevator skins in the areas where they were rubbing by bending slightly using my fingers while also making small adjustments to the rod end bearings.
With the elevators and horizontal stab attachment and rigging complete, the next step is match drilling the elevator horns to the flange bearing that is attached to the aft-spar of the horizontal stab. This is the "pivot" point for the elevator where the two elevator horns are attached together.
 |
| The is the drill bushing used to ensure a nice straight pilot hole is drilled through the flange bearing to the elevator horn. This bushing is supplied with the kit and comes a little oversized for the flange bearing diameter. The plans say to chuck the drill guide in a drill press and "turn down" using sand paper as required to get a nice snug fit in the flanges bearing. Worked out great. Additionally, they want you to fabricate a spacer to place between the flange bearing and the elevator horn. The dimensions for this spacer are given in the plans, but I had better luck just trial fitting different shaped/size objects until I found something that worked. |
 |
| Here's the drill bushing being palace in the flange bearing. |
 |
| This is the setup I used to clamp the elevator horn to the flange bearing. At first, I couldn't figure out the need for this spacer and clamp requirement. However, once I started drilling, I discovered this setup aids in maintaining the rudder horn and flange bearing positioning. Without it, there may be a tendency for the elevator horn to want to "push away" as you push with the drill bit. Don't think you need to get crazy here with the clamping, just something to stabilize it just a little. |
 |
| Match drilling the #17 pilot hole from the flange bearing into the elevator horn. During this step, the elevator is secure in the "trail" position by securing the elevator counter-balance arms to the horizontal stab. I used small clamps and will show and describe this a little more later on. |
 |
| Another view of match drilling the elevator horn. Once the #17 pilot holes are drilled, the holes will be stepped up to .25" holes to accommodate a AN4 bolt used to connect the two elevator horns. |
I mentioned above that to accomplish the match drilling of the elevator horns, the elevators are placed in the "trail" position by securing the counterbalance arms to the horizontal stab. During this step, I took the opportunity to check the "straightness" of the two elevators. While this step is not called for in the plans, I just wanted to see what I ended up with. I discovered there appeared to be approximately .25" difference (vertical) between the left and right trailing edges. Considering there are many things that could contribute/cause this situation, I wanted to investigate a little more to see what I could come up with. Just by visually looking at the trailing edges, it appeared the separate elevators were very straight, but there was an obvious higher/lower offset between the two. Keep in mind, the trailing edge can be a deceiving way to check the overall straightness of the elevators. A slight twist or a little bit of an offset in the counterbalance arms could all contribute to what appears to be the mismatched trailing edges. With that in mind, I used several methods ranging from laser levels to strings to determine the straightness of my elevators at various locations other than the trailing edges.
In the end, I found that it appeared that my elevators were,for the most part, straight. It looked like there was approximately a .25" difference between the two. So now the question was..do I just accept the .25" offset and go ahead and drill the elevator horns with the counterbalance arms secured flush with the HS, ...which, once done the elevators will be permanently attached together and you get what get as far as elevator symmetry. Or..., when I secure the counterbalance arms to the HS, I could offset them approximately .125" (one up and one down) to achieve the straight/level trailing edge.
For further advice, I did send an email to Vans to check my options. They replied that this situation is fairly common among all RV models and they typically recommend to secure the counterbalance arms flush to the HS and accept the "apparent" offset in the elevator trailing edges. They indicated there should be very little, if any, noticeable issues with this situation.
However, after much consideration of all the specifics of my situation, I decided to offset the counterbalance arms to achieve "straight/level" elevator trailing edges. I used a small shims under my clamps to offset on elevator counterbalance arm up approximately .125" and the other down the same amount. This offset is barely noticeable and, in reality, will only be noticeable on the rare occasion the elevators are in the "trail" position.
So with the decision made, I drilled the horns and bolted the elevators bolted together . I once again then used my lasers, strings, levels, etc.. to check the elevators. It appears everything looks good and I am happy with the results. Keep in mind though, I probably did over think this and could have just accepted the offsets and it probably would have been fine in the long run. Just putting this info out there for those that may see this situation with their builds.
 |
| This is one of the elevators secured to the horizontal stab using a small clamp. Not really visible in picture, but I placed small (approx. 1/8") shims under the clamp to "offset" the counterbalance arms (one up, one down) to achieve a level/straight trailing edge as described above. Tongue depressor was part of my extensive laser testing procedures:) |
 |
| Once the elevator control horns are bolted together in the previously drilled hole through the flange bearing, it is time to drill the holes in the horns for the elevator pushrod bolt holes. A #40 pilot hole is first drilled in one horn and then final drilled to #12. A drill block guide is fabricated with a #12 hole to be secured as pictured to ensure the hole is match drilled as straight as possible to the other elevator horn. One thing I did here that was a little different than the plans called for was that I drilled the #40 hole on the first horn and then drilled a #40 hole in my drill guide block and mashed drilled the other horn with a #40 hole first. The plans seem to indicate to go right to the #12 hole in the second horn. I felt my way made that second horn a little easier to drill #12 with a #40 hole already in place. Personal preference here as always. |
 |
| View of other elevator horn prior to drilling. |
December 30, 2016
Finally got some time to get the rudder installed to the aft-fuselage. Pretty easy process, and can be done solo, but is nice to have a helper if available. Once installed, you are checking for freedom of movement, clearances, and overall fit. The rudder has three rod end bearings that are used to connect it to brackets on the vertical stabilizer. The plans give measurements on how far to screw in the rod end bearings to get you in the ballpark for the first install. I found these measurements to be very close. However, after testing the fit, I removed and screwed in the top and middle bearings one more turn. This still provided all the required clearances and also improved the "visual lines" of the joints of the vertical stab and rudder. Additionally, to ensure all three rod end bearings were in proper alignment I used a metal rod (same one are used to hang from ceiling as seen in VS section of blog) to slide through all three bearings to check for possible binding.
With all the "metal" components of the aft-fuselage assembled, I should probably move on to attaching the fiberglass fairings (included with the empennage kit) that are associated with these components. Would probably be easier now than later given all the pieces are in place and I will have to disassemble and store before moving on with building other sections of the plane. I may not be able to assemble like this again until I'm in a hangar. I just won't have the room as I continue to build and the plane is assembled. I think I'm just not ready to learn a "new skill" at this time and I want to get started on the wings. Will have to think about this a little more.
 | |
| Here's the Aft-Fuselage with all components installed. This is what you end up with (minus the fiberglass fairings) when you complete the empennage kit as delivered from Vans. Sorry I skipped a few steps showing the assembly, but it's actually pretty easy and quick (once the rigging is complete). Unfortunately, due to space limitations, I will have to dissemble all this and store all the pieces until final assembly. Oh well, it was fun this time and sure it will be even better a few years from now:) |