I fixed the trailing edge of the rudder fairing the other day - it was too short, so I added a few layers of fiberglass to it to extend it. There are a 100 opinions on the best method to attach fiberglass tips. Some just pop rivet them (that's what the plans call for), some rivet plus epoxy, some leave the edge as-is, some smooth over it with fiberglass...and the list goes on and on. I don't love the look of the pop rivets, so I think I will ultimately fill the edges between the fiberglass and aluminum with micro and extend it over the pop rivets. The gotcha with that is the fact that movement between the different materials (heat/cooling) could cause cracking, kind of like a drywall seam. One trick I've seen is to use proseal on the flange to give it a little extra holding power on top of the rivets, then lay a single layer of lightweight fiberglass cloth over the seam before putting the micro on. That's probably the direction I'll go. Maybe a little overkill, but better than staring at cracks in 5 years.
Next up is the vertical stab tip. I trimmed the aft edge to give it a 1/8" gap with the front edge of the rudder.
Unfortunately, the only way to line up all of the different fiberglass is to get the parts in their final positions. The horizontal stab is too long to fit where the plane has been for the last year. I pushed and pulled and rotated the plane to an angle so I could fit it on again. With the engine on, I can no longer get to my toolbox though. I'm going to need to move the bandsaw and drill press so I can push the plane backwards a bit. I just put a few bolts in to keep things from moving around. I'm going to take it all apart again to paint, so no point in going overboard.
The aft side of the vertical stab tip is open and needs to be closed off with fiberglass. Again, there are a million ways to accomplish this. I chose the foam route. Basically, you cut some foam to shape (I'm just using regular old Home Depot insulation) and inset it 1/8" or so below the edge. Then you put flox around the outer edge to anchor the fiberglass cloth. Then a few layers of fiberglass cloth go on top of the foam and get embedded in the flox. Once that is all set up, you can pull out the foam and finish the surface using micro.
