Friday, February 2, 2018

Section: 12
Hours: 7

Today I continued working on the fiberglass tips.

Here I'm working on slowly finishing the fit for the rudder bottom fairing. I glued 80 grit to a long straight piece of fir to make a long board sanding block. The long board ensures a straight edge. I iterated multiple times between sanding and checking the fit until I had all the gaps closed. You have to be really careful to not take off too much.
 Here's the final fit. I still have to bevel the bottom edge to clear the tail wheel and also fit my FlyLEDs tail light.
Next I worked on the rudder top fairing. I set the micrometer to the depth from the skin edge to the flange of the rib at the top of the rudder. Then I used the micrometer to scribe a final trim line on the fairing. I then used the band saw to cut close to the trim line and then sanded using the long board.
 Here is the initial trim. I cut off the back of the flange because the gap between skins is too narrow to fit.
The front of the fairing did not fit into the corners of the rudder metal so I did some more shaping using a drum sander on the dremel.

Here's the final fit after trim, dremel and long board sanding.
Next I trimmed the elevator tips using the same measure and scribe method as I used on the rudder top. I used masking tape to mark the trim line to make it easier to see while trimming.
Fiberglass parts shrink after fully curing which leads to some fit problems. When I initially pushed the elevator fairings on, there were large gaps between the fairing and the metal skins. I inserted several popsicle stick spacers to push the fiberglass to the proper width to match the metal skins. This is an essential step before sanding the edges to a final fit because the geometry changes when the fairing is forced to the full width.

I did a preliminary trim of the h-stab tip but as you can see in the picture below, the shape does not match elevator fairing. The tip is sucked in and too thin. I could add (a lot) of bondo to fill out the shape, but that adds weight and is not ideal.

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