Fiberglassing is kinda crazy

[GingerFly]

I just recently finished fiberglassing my MM corsair, and it turned out great, using 1 oz fiberglass cloth, and 30 min epoxy resin, thinned with denatured alcohol. But then I somehow ended up stepping directly on the right-wing, my plane making a blood-chilling crunch... however when I inspected the damage, I only found a single half-inch crack on the leading edge ( I had reinforced the leading edge's and the nose with a layer of 5 oz fiberglass). I'm sure I missed some damage, possibly hidden under the primer, but the fact that it was able to handle my full body weight, and survive still perfectly fly-able, is kinda crazy. If you are considering fiberglassing your foam/foamboard plane, I would definitely recommend it. It cost me about $40 total, and I should be able to fully cover 2 small models (30-inch wingspan)

 

[trey]

I've done a few planes with fiberglass wings, and it is awesome. The only drawback I found is that it is easy to add weight without realizing it. I did that one time, and it turns out, there is no way to remove that weight. Haha.

 

[The Hangar]

I just recently finished fiberglassing my MM corsair, and it turned out great, using 1 oz fiberglass cloth, and 30 min epoxy resin, thinned with denatured alcohol. But then I somehow ended up stepping directly on the right-wing, my plane making a blood-chilling crunch... however when I inspected the damage, I only found a single half-inch crack on the leading edge ( I had reinforced the leading edge's and the nose with a layer of 5 oz fiberglass). I'm sure I missed some damage, possibly hidden under the primer, but the fact that it was able to handle my full body weight, and survive still perfectly fly-able, is kinda crazy. If you are considering fiberglassing your foam/foamboard plane, I would definitely recommend it. It cost me about $40 total, and I should be able to fully cover 2 small models (30-inch wingspan)

Do you have a link to the epoxy you used?

 

[Whit Armstrong]

I've done a few planes with fiberglass wings, and it is awesome. The only drawback I found is that it is easy to add weight without realizing it. I did that one time, and it turns out, there is no way to remove that weight. Haha.

I've been thinking about glassing a couple planes, and it seems like a good idea to remove the paper from the surfaces you're going to cover. That might save weight.

 

[GingerFly]

Do you have a link to the epoxy you used?

I used Bob Smith Industries 30 min slow cure. https://www.hobbytown.com/bob-smith...30-minute-epoxy-9oz-bsi206/p-xtychdgawqsbg4yz

 

[GingerFly]

Prep:
1. sand the entire surface very roughly (I used 120 grit sandpaper)
2. using a brush or compressed air, clean all the dust off the surface

Application:
1. mixed the epoxy, then added a little bit of denatured alcohol at a time, 'till it is nearly water thickness.
2. after laying the fiberglass over the surface, using a standard 1.5 in brush (use a brush sized appropriately to your plane size, use a larger brush over a smaller one)
3. make sure to not have any dry spots, as the fiberglass won't stick there (obviously). Use a light to look at the surface at an angle, dry spots will have a different sheen.
4. lay toilet paper over the surface, and lightly press down over the whole surface, this removes the excess resin (the less excess you have, the better, to keep weight down, and maximize strength) You can also bunch up a ball of toilet paper, and dab the surface (I found this worked better in tight corners than just laying it down)
5. (optional) for maximum weight reduction, taking a paper towel that has been dampened with isopropyl alcohol, and gently wiping the surface can remove even more excess resin.
6. wait and hope...

tips:
-Do one surface at a time, mixing a small batch of resin individually for each one. You don't want to end up trying to apply when the resin is past its work time, as I ended up doing on my horizontal stabilizer, leaving the fiberglass not fully adhered to the foamboard in some places.
-let it sit for a full 24 hours after application before handling
-align the weave of the fiberglass perpendicular to the leading edges of your surfaces.

 

[GingerFly]

I've been thinking about glassing a couple planes, and it seems like a good idea to remove the paper from the surfaces you're going to cover. That might save weight.

In the flight test video they did a few tests, and the adhesion strength was worse when the paper was removed. to keep the paper from getting saturated (keeping the weight down) I think I've seen people use shellac and possibly hair-spray to seal the surface.

 

[The Hangar]

Thank you for the link and write-up, it’s very helpful. You said the epoxy was good for about 2 mini builds?

 

[GingerFly]

Thank you for the link and write-up, it’s very helpful. You said the epoxy was good for about 2 mini builds?

the epoxy will probably do 3, but the fiberglass (I got 1 square meter) will probably do 2 (although you would have to be very efficient with your usage, and not have much waste)

 

[Merv]

The polyurethane used for wood also works well for fiberglass.

 

[Piotrsko]

Im a fan of titebond and light dacron but for pull stresses only. Kinda like string packing tape but not glue sensitive

 

[PsyBorg]

This thread makes me itch...

 

[GingerFly]

This thread makes me itch...

maybe I just got lucky, but I never experienced the barrage of thousands of tiny cacti that I've heard of.

 

[PsyBorg]

maybe I just got lucky, but I never experienced the barrage of thousands of tiny cacti that I've heard of.

Then you haven't installed fiberglass batting in a house haha Or on an aircraft carrier for that matter.

 

[Piotrsko]

Or an airplane

 

[Bigeard]

I've done a few planes with fiberglass wings, and it is awesome. The only drawback I found is that it is easy to add weight without realizing it. I did that one time, and it turns out, there is no way to remove that weight. Haha.

I know you have to be careful by additional weight but within reason I am surprised that this method of reinforcement to the nose , parts of the wings and fuselage is not more widely used ?