Wing Tips (4)

I haven't had the mental energy to do much work on the plane lately - funny how studying nonstop was so easy as a 20 year old.  Now between work and flight training, my brain is pretty much done by the end of the day!  My flight lessons got canceled this weekend due to low ceilings though, so I was able to get a few minutes out in the garage.

The rib that goes inside the wing tip has to be built up with some fiberglass to even it out with the wing tip so the tip doesn't get divots in it when it's all riveted together.  I mixed up some epoxy and flox and spread a thin layer inside the wing tip, then slid the rib in place.  I did that yesterday, and by today it was all set up and seems to have filled in all of the uneven waves of the rib and created a nice solid flat joint.  I drilled holes through the rib, countersunk the tip holes and riveted it all together.  I don't love using the rivet gun on fiberglass.  It seems pretty easy to squish the fiberglass.  I'll probably end up laying a very thin piece of fiberglass cloth over the rivets on the outside - a method some people use to keep rivets in fiberglass from slowly working loose over time and popping through the paint.

Continuing with random things that are always on the list to do, I added a second standoff bracket for the longest sparkplug wire.

I need a better paint gun before I get deep into spraying paint, and Harbor Freight has one that is consistently raved about by pros.  It was on sale now, so I ran into town and picked it up.  I also picked up a light that attaches to the front of the gun.  My biggest complaint in all of the painting and priming I've done up until now is that it's so hard to see with shop light - we'll see if this helps.

Next up for the wing tips is to attach all of the nutplates to the edge.  The screws to attach the tips will go through the wing skin, then through the underlying fiberglass of the wing tip and into the nutplates.  I also need to trim down the aft edge of the tips.  They're okay as-is, but they extend about 1/4" past the trailing edge of the aileron, which looks a little goofy.  One tip also has a curve in the trailing edge, so I need to cut it apart and re-fiberglass it to flatten it out.  After that, the last thing to do will be to attach the light lenses.  Then it'll be on to the canopy fairing.

Wing Tips (3)

I riveted the ribs into the wing tips.  I'll have to do a little research and see if builders fiberglass in the ends or just leave them open against the ailerons.

There's an internal rib that runs perpendicular to the edge and spans the wing tip to stiffen it.  I bent and fluted the flanges to make them match the angle of the tip.  I have a feeling that the tip fiberglass is going to get dips in it when I rivet the rib in though.  The flanges of the rib just aren't perfect enough of a match to keep that from happening.  I spent a lot of time trying to get the flange angles right, but decided fixing an uneven fiberglass surface with a little micro/filler would be easier than trying to make everything match so perfectly that there are no surface blemishes.

The hardest part of all of this was finding a way to translate the rib location to the outside of the wing tip so I could lay out the rivet line.  The instructions say to just use a bright light to help create a shadow of the rib, but that must be from back in the days before they supplied the fiberglass with the grey gel coat.  I tried every light I had and couldn't see a thing.  What ended up working pretty well was using a couple of strong magnets positioned against the rib flange on the inside and then matched up with magnets on the outside.  These rare earth magnets are borderline scary to use!  It's amazing how strong they are.

The next step will be to put a flox and epoxy mixture on the inside of the wing tip where the rib goes, then embed the rib into it.  Hopefully that'll provide a solid surface so that when I rivet the rib in, the wing tip won't get divots.