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.