July 18, 2020
The next step in mounting the horizontal stabilizer is to drill the holes that set the incidence. The instructions say to use a 3/16″ space under the rear spar to set the incidence of the horizontal stabilizer. We used trial and error with various size drill bits that were all around 3/16″ to get it perfect. Even swapping from a #15 to a #14 drill bit under one side would move the opposite corner almost 1/32″, so we took a bit of time to get it level.
The instructions also say to use the tooling holes as measurement to verify the height of everything, but that doesn’t work. The tooling holes they tell you to use for reference aren’t centered in the rib, so one ends up being ~40 mm above the deck, and the other is ~50 mm above the deck.
We made our own marks and reference lines to make sure they were consistent for setting the incidence, but this would be one spot where a laser level would come in really handy. With a lot of iterative measuring between a skin/longeron intersection on the fuselage and the corner of the horizontal stabilizer we were able to confirm the stabilizer was square with the fuselage.
A dry-erase marker worked great for tracking the measurements of each corner and visualizing the changes required. Eventually we ended up getting everything straight and drilled and got both elevators installed. We put the pushrod in, set the neutral position and locked the rod ends in place. Another satisfying day of progress.
-Paul
(Total Build Time: 438.6 hrs)