Project: TerryS     -     Entry

Nov 19, 2023 20 Windscreen fairing done! Category: Fuselage
I spent a few more days finishing this up. Simple duplicolor rattle can hi-build primer to identify defects that you wouldn't otherwise see. Then a bit of glazing putty for a few pinholes that escaped the epoxy top coats. Wet sand, repeat.

I finally got this to a good contour and surface quality, so last night as soon as I could get some help tp position this without making a mess, I went ahead and permanently attache dit via the sikaflex process.

Yesterday was the perfect window for tis because it was 60% humidity and 65 degrees, with forecast for 3 days of rain starting last night. As you may recall, humidity is what causes sika to cure, so once you get it applied, the more humid the better.

Larry Larson mentioned in his Kitplane articles that he almost glued his canopy shut with this stuff. I've been been using clecoes in 4 strategically placed holes to position this consistently, during fabrication, so it seemed to me that there wasn't much benefit to trying to glue this on with the slider canopy closed.

I masked and prep sanded the faring with 60 grit, and masked and scuffed the windscreen and aluminum fwd skin with red scotch bright. Then prepped everything with sika aktivator and primer per the allowable time windows.

I only applied Sika 295UV to the airplane side, and then smeared it out to what I though was a thickness that would allow full coverage but not be so thick that it would cause problems with smooshing the fairing down more or less flush.

Sika recommends a certain gap to allow for expansion, so when I taped off the airplane to do my initial wet layups for this faring I had intentionally bridged the gap at the windshield base to leave a little gap there that I could fill up later with sika. Now I laid a thicker bead in there.

I estimate the thickness of sika that I ended with to be probably .25" at the intersecting line of the windscreen to fwd fuselage going, transitioning to maybe .010 at the edges.

I finished it off with a fillet all around to seal the edges, but due to some reshaping after removing the edge mask, I ended up with several areas that had to be corrected and trued up after it dried, so this morning I went back and accomplished that with nothing more than patience and my fingernails.

As we know, the 295UV won't stick well anywhere that primer isn't first applied, so I was able to get everything without drams, but it does soften that cheap rattle can primer, so I've got several spots on the fairing itself that should probably be hit with some scotch bright or wet sanded with 400 grit and touched dup to make it pretty, but ultimately, the stuff will all have to be done by the paint shop anyway, So I may just leave it for now.

Once everything is set up good and hard I'll have to go back and fill in the cleco holes, but for the most part this is done and I'm really, really, glad this is done.


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