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Old 07-30-2019, 12:19 PM
stillkickin is offline
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Plugging Holes in Cowling

I found a fiberglass (thin light duty) cowling that will fit my Astro Hog. It was on another plane and has a hole on the side big enough for an engine cylinder head. My new RCGF 15cc has been shipped and it will be mounted upside down.



So, what would be the best way to close up that hole?


Thank you,
sherm
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Old 07-30-2019, 01:07 PM
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I always just lay a cpl layers of glass on the inside of the area then use light Bondo or spot putty on the outside then prime and paint. Make sure you clean the area well with acetone etc so the new glass will stick....others may have better ideas or pointers but really not a hard fix. If you're not happy with the results put a logo/sticker over it.
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Old 07-30-2019, 01:09 PM
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Quote:
Originally Posted by stillkickin View Post


So, what would be the best way to close up that hole?


Thank you,
sherm
Since you asked... I would say the best way would be a new cowling.

If you're set up for fiberglass work with materials and skills, then you'd probably already have it done.

If you're not set up with the above, you might end up spending more $$ on materials then a new cowling would cost. If it's not a large cowl, I'm betting it would be less then $35...

Some of this might depend on if you know the origin of the cowl you'd like to put on it.. If you know the origin, look at Fiberglass Specialties to compare price of a new cowl vs. cost of material(s) and time spent to patch the old one.

Just a thought here. It can be done of course, but you might want to look at time, skills, and money... unless you want to do it for the experience. If that's the case, I'll let those with alot more fiberglass experience comment. I would think a semi-plug would be the way to go, to form it, then glass it from there.

Maybe I'll learn here too though. Good luck with it.
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Old 07-30-2019, 02:58 PM
scale only 4 me is offline
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Yeah,, one way is shape some Styrofoam on the inside to fill the hole allowing to stick out some,,, epoxy it in firmly, , then carefully shape the foam to match the outside contours,,, might need some Spackle etc to get smooth,,,, once you're happy with the shape,, then take 2 oz or 4oz cloth and epoxy resin and coat the outside letting it over lap a bit,,, a second maybe third coat of epoxy so you can sand everything smooth so it looks ready for paint,,

Once happy with the outside, you can just poor some acetone on the inside and the foam will melt away, Sand the inside clean and smooth and then add another layer of glass and cloth for strength,, Cut the cowl for your new engine and now you're ready to paint,,

Not all that hard really,, I've don't it a few times

Good luck
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Old 07-31-2019, 08:03 AM
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Thanks guys for the replies. Two really easy was to fix, it seems. I've thought of DGrant's idea of buying new is also good but I do enjoy building things. I just wished we had more kits in the industry to choose from.


You have a good day,
sherm
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Old 07-31-2019, 04:46 PM
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I've made lots of cowls. It's easy and would be a much better bet than trying to fix a big hole in an existing cowl. Just make a plug out of foam the shape you want then lay it up in glass. After you've smoothed and primed it, dig out the foam and make the cutouts for the engine. Then slap a couple of coats of paint on it and you're done.

carl
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Old 08-01-2019, 08:47 PM
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A fast way is the put packing tape on the outside of the cowl if the hole is not contoured. Lay the fiber glass with epoxy/resin and let try, once dry rip off the packing tape. You may need some bondo to fill any gap.

sand, smoth, prime and paint to finish.
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Old 08-06-2019, 08:40 AM
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So your saying it would be easier to make a new cowl than to patch a hold. Sorry but a plug fiberglass ing and paint would take considerable more time and skill.

I'm thinking if he doesn't no how to patch a hole he surely will have a tough time making a decent cowl
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Old 08-07-2019, 11:56 AM
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Quote:
Originally Posted by crazyjoe View Post
So your saying it would be easier to make a new cowl than to patch a hold. Sorry but a plug fiberglass ing and paint would take considerable more time and skill.

I'm thinking if he doesn't no how to patch a hole he surely will have a tough time making a decent cowl

You got that right, it's just a first time for me. I'm trying the Styrofoam system first. I think I can handle that.

Yes building a new cowling from scratch would be major for me at this time.


sherm
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Old 08-08-2019, 07:49 AM
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If you are patching holes in a cowling, start by washing the cowling with warm water and dish soap inside and out, then clean the inside with acetone and a one or two inch chip brush. After dry, abrade the inside real good with 80 grit sand paper, and remove the dust. Next using clear packing tape plug the holes from the outside. Now you can use 4 to 6 oz. glass and medium CA to patch the holes. Cut two tailored plies of glass for each hole around 3/8 larger than your holes, now using the CA wet out the entire area of the hole, be generous, lay first ply down and rub with finger tip wetting through cloth, add more CA and place second ply, again using finger tip rub through. Spend no more time than around one minute getting the two plies down. Spray with kicker, once flashed remove tape and abrade the outside of cowling with 80 grit sand paper and spread your bondo. This also works on wheel pant repairs. The repair generally takes less than an hour usually.

Bob
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