butlern

My Feedback: (15)

I have a couple of questions regarding my efforts to repair a foam core and fiberglassed wing:

I needed to cut out some of the original foam to access the gear mounts/spar (the area that required repair) and I have since made the repair and epoxied new foam back in. This area was essentially the leading edge, and I just recently finished shaping the new foam to match the existing contours. So here are my questions...

1) What type of filler/finishing resin should be used to smooth the foam surfaces (fill gaps between old and new foam, and fill dents in the old foam) before I re-glass this section of the wing? I was thinking that I might use epoxy resin with mircoballoons, but I don't want to add too much weight, and I am a little concerned that it will sag.

2) I have also read that polyurethane glue (foaming, Gorilla Glue type stuff) could be used to fill before re-glassing, as it will bond, expand and sands easily. But can I glass with epoxy resin over the top of polyurethane?

3) As a last alternative, I could reglass over the dings, small gaps and dents on the foam and then fill the low spots with putty after I finish re-glassing.

So, which is best? If the first method is prefered, which filler would you recommend be used... thickened, sandable epoxy resin (like with microballoons?)?

By the way, there's no balsa sheeting. The fiberglass was applied directly to the foam core (it's an old Byrons Originals kit).

Thanks!

Deadeye

Why not fill your lows and dents with a lightweight spakle, then fiberglass? Epoxy and microballons is overkill for just filling dings, IMO, and much harder to sand and apply. Also, next time you work with wood and foam, give polyurethane glue (Elmer's Ultimate) a try. Your epoxy bottles will collect dust after you have. You can pant, stain, and fiberglass over poly glue.

butlern

My Feedback: (15)

Deadeye,

I considered this... but my concern is that since there is no balsa sheeting, the fiberglass skins provide the essential ridgity and strength... I suspected that if there was spackle between the foam and the glass, the glass could potentially pull away from the wing (I am assuming that the spackle does not bond the foam... so the glass would essentially be floating above the foam wing).

Am I wrong, or will spackle bond everything together well enough? If it will, would you use vinyl or standard lightweight spackle?

Thanks for the reply!

Deadeye

If you fiberglass after you fill, there is no way the spackle can go anywhere. Vinyl spackle should work well for this application. Heck, any light weight filler would work.