Drilling the elevator horns - 1.5 hours

I need to drill the elevator horns for the pushrod. My horns are fairly aligned, but I would say the left side horn is the one further back. So I marked the hole according to the dimensions on the drawings.

I started drilling the hole first to #40, then up to #30. Then I made my spacer block and drilled in a drill press to get a good drill jig. Placing this in between the horns, I marked the next hole by twisting the drill with my hands.

This is when I noticed a whoops. 

Turns out the other horn is a tad lower than the other one. And surprise, surprise the tallest one is the one I chose to drill. Making the other hole with less edge distance than the other 

To be exact the measurement on the other horn will be about 0.305" as opposed to 0.375" as stated on the plans. Better call Vans.

When I called Van's Tech support Monday morning, we went through a few options of what I can do. Even adjusting the "height" of the elevators was an option if the pivot point isn't drilled. I asked about welding. Vans response is it's possible. But the disadvantage there is that the power coating needs to be removed for welding and a new coating be applied. Very important on these weldments as they can easily start to rust. Ultimately tech support felt I was going to be just fine with my particular issue. Although I didn't have 2x edge distance (0.375") I was better than 1.5x edge distance (0.28125") and it was still very safe.

 Personal note: I can take a file and walk that pilot hole down, allowing my new pilot hole to gain a few thousands in edge distance. Theoretically if I do it perfect I can move the pilot hole 1/32" (0.03125")....realistically I'll likely be able to move the hole 1/64" (0.015625"). That would allow a final edge distance of 0.320"

Finished mounting the horizontal stabilizer - 4 hours

Now that I have the front of the HS set. It’s time to set and drill the rear spar of the HS to the fuselage. 

I placed 3/16” drill bits as spacers under the rear spar. I also placed a level and a laser level on the HS just to make extra certain I was in good shape. 

Next I went to double check the angle of incidence something seemed really off. The manual seems to suggest to reference the tooling holes in the ribs as a guide, so placing a long drill bit in the tooling holes reveals this is not a good reference. The tooling holes of the HS-00005 ribs at the front are just fine, however the tooling ribs at the back is way off. 

So, what to do now…Well, After a series of head scratching moments I decided to draw center lines on the forward spar and the rear spar. Then I can compare these with the distance off of the aft deck. Zero angle of incidence means that the center of these 2 spars will be the exact same. Sure enough the 3/16” spacer at the back is almost spot on, It does need to be increased by a tiny amount (just a tad over 1/64”) Nothing a  layer of masking tape on the aft deck can’t fix. After double and triple checking the measurements….I was ready to start drilling. Access is so good for using a drill jig.

 

Began mounting the horizontal stabilizer - 8 hours

Today was the day. I need to mount the horizontal stabilizer. This was a part of the build I was dreading as I know how frustrating it can be getting these holes drilled. I haven’t even started and I’m already stressed out. First things first, I need to make sure everything is level. Working on an uneven concrete floor…Not an easy task. But using a jack and shims….I got everything right.

I measured center on the fuse aft deck using the callipers and drew a black line. I continued the line up the aft bulkhead and center runs through the center of the tooling holes. So far…Perfect.

The firewall and main spar are perfectly level, however the aft end of the fuse is just ever so slightly out. The level bounces between 0.00 deg and 0.05 deg. Despite my best efforts to have it perfectly 0, when riveting there can very slight movement that can eventually get locked in. Honestly its not a huge deal. We are talking about 1/16” out over a distance of 8’. I think I can live with that. 

 

Next I set up a laser level down the longitudinal axis if the aircraft. Positioning the level from a center point on the firewall, to a center point on the end of the aft deck. The true center of the aircraft is just a tiny bit (1/32" to 1/16") to the line drawn on the aft deck. 

  I am now ready to start final fitting and positioning the horizontal stabilizer. Placing the stabilizer on the aft deck. I fist centered and clamped the rear spar of the HS to the vertical bars WITH the 3/16" spacers (Using 3/16" drill bits). I also placed the F-798 shims under the forward HS spar.

Next I lightly clamped the forward spar to the aft deck. Now came a series of measurements from the firewall to the tips of the HS. This sounds simple enough but I must have measured a million times from a number of different points. Making tiny adjustments to the HS, remeasure. Check measure again. so on and so on. 

 

 

I'm now locked in and ready to drill. Very carefully and very slowly I marked the spar flange and started to drill.  

 

At this point I notice that the mounting hole on the left side of the aircraft will come close to the edge of the spar flange. The edge distance on the longerons and H-710B angle underneath are excellent. 
There's not really much I can do...Twisting the HS for better edge distance on the spar flange will mean that the HS is now out of square. I don't know what Van's Aircraft will say....Its Saturday and tech support is closed. I'm beginning to thing that I will need to add a double of some sort to help. Next I removed the HS from the fuselage and continued on drilling the inboard mounting holes. Once the inboard mounting holes are located, I then placed the shims underneath and marked the new holes.

 While everything is still drilled to #40....Now is a good time to work on those doublers. If they are in fact needed...Then at least everything will be drilled and reamed as an assembly. I hate to think how tricky they would be to do much later. I went to the basement and found that I had some extra 0.187" material. Using the router I created a radius on the doubler material allowing it to nest to the HS spar flange. 

After cutting the doublers to size I then marked holes to them using the #40 drill size. (If your wondering why I made two doublers L and R. It's simply for symmetry). 

 Now I very slowly started opening up each hole from #40 to #30. Then to #21. Getting this precise is a pain as the holes I have good access to are the two outboard mounting holes, not the two inboard. After much work and carefully drilling...It was time to ream the 4 holes to final size (3/16"). And it turned out very well.

 

So on the left side, the bolt hole is close to the edge...I have an edge distance of 9/32"

So the question of the day is "will it be ok? or will I need the doubler?". Calling Van's tech support on monday morning gave me the answer I was looking for. The answer was both.....It will likely be ok...but having the doubler installed will be a great peace of mind that it will be very strong. 

So that is what I will do. Glad I fabricated it when I did. 

 

Prepping the horizontal stabilizer for mounting - 4 hours

 On initial fitting the horizontal stabilizer. I notice that the F-711C vertical bars interfere slightly with the flanges on the HS-00005 ribs. This is a bit of a head scratch-er on how best to handle this. I am reluctant to remove material from the F-711C vertical bars, but trimming the flanges are near impossible. Well....I ended up doing a little of both.

 First I decided to chamfer the aft outside edge of the vertical bars. It soon became apparent that alone won't be enough without removing lots of material.

I then started in on the impossible task of trimming the flanges. To do this I cut a piece of 0.016" scrap material and carefully slipped it under the flanges.

After a lot of filing with a tiny file...I finally managed to remove the material. Keeping the shims under the flanges, I can then use 3M scotchbrite to buff the cut edges. After masking off the piece, a coat of primer...Ready to start mounting.

 

Preping the aft deck for mounting the horizontal stabilizer - 2 hours

 Before I mount the horizontal stabilizer I need to mark out the complete outline of the F-718 longerons and F-710B angle on the top of the F-714 aft deck. Once the outline is made. I marked the mounting location of the bolts in red. They are to be centered in the exposed flange of the 3/4x3/4x.125 longeron. The dimension works out to be 7/16" from the outside edge of the longeron.  

Finished riveting the HS#2 - 3 hours

I woke up this morning excited to get going on finishing the HS. Just a couple of quick hours of riveting and I am done! Ready for the pre-close inspection....Again.


 In retrospect I am way happier with the second HS. Its extremely clean, not a single oops rivet (Although I still have to rivet it closed after inspection - Knock on wood), Once I have completely riveted though I will weight it against the first one. I suspect the first weighs considerably more due to the 2-part epoxy.

Started riveting the skin on HS#2 - 4 hours

Took a bit of a slow day today. I cleco'd the skins to the HS-707, HS-708 and HS-706 ribs. I then proceeded to rivet the skin to HS-707 both L and R sides.

I then deviated from the plans slightly as I riveted the HS-706 to the front spar assembly. The plans have to do this step after the skins are riveted and the first go around was really tough for my to get a good bucked rivet in that tight space. I then set the assembly into the skins and re-cleco'd everything.
 
Began the long, but quite enjoyable task to rivet the skins on. Managed to get a ways through before I called it a day.