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fiber glass cowling, how many layers?

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fiber glass cowling, how many layers?

Old 07-13-2002, 09:36 PM
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Default fiber glass cowling, how many layers?

Hi
I'm trying to make a fiber glass cowl and I'm not sure how many layers I need to use, I'm using 6 oz cloth, does anyone know?
Thanks guys,
Edwin.
Old 07-14-2002, 01:13 AM
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Default How many?

Well, I can't resist quoting the infamous Billy Carter, from an old Tom Snyder program...

Tom said, "Billy, you're a peanut farmer. With all the emphasis on health these days, tell me... Are peanuts fattening?" Billy paused for a moment, and then replied, "Well, I guess it depends on how many ya eat!"

(Sorry) Anyway...
A couple of layers of 6 oz. cloth should be fine, but it really does depend on how much abuse it will get. You can probably make it lighter, if it doesn't have to stand up to extreme vibration, etc..

Best approach, as always, is to make some small test parts.

There's a tutorial on this at http://www.cstsales.com/fiberg0.htm and there's more information on my non-commercial web site as well, at http://www.nextcraft.com/rcdesignandbuilding.html

Have fun!
Old 07-14-2002, 12:41 PM
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Default fiber glass cowling, how many layers?

Ed: In the cowls I have made, I used 2 layers of cloth. I use the fiberglass cloth found in body shops. This is heavier, and two layers does the job nicely, Use only enough resin to adhere the cloth to the form and fill the weave. The strength comes from the cloth, NOT the resin.
The trick is that before adding the second layer of cloth, you have to wet sand the previous layer. I use a 220 wet paper wrapped around a small sanding block.(I use a small foam sanding pad, as these are not affected by the water) It is important not to let the paper clog. Keep dipping it in water to rinse the build up away. I use the bottom tray from a take out roast chicken.
Anyway, back to the cowl. When you sand you might notice some shiney areas. These are low spots and they need to be filled. I circle these with a magic marker. Sand the low spot ,to remove the shine, and fill it in. I use a mix of phenolic micro balloons and resin mixed to the consistancy of peanut butter. Fill all the low spots, allow to dry overnight and wet sand again. When it is flat and even you can add the next layer.
I also use this micro balloon slurry to make fillets for intakes and outlets on the cowl.
Hope the above helps. Happy landings, Tony
Old 07-14-2002, 05:10 PM
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Default fiber glass cowling, how many layers?

Are you making the plug, mold and then the cowl or do you have a mold already built and want to know how many layers?
Or, are you making a cowl using the lost foam method where you make the part out of foam, glass it, then eat the foam out from the inside?
For the cowls and wheel pants I make, I use 1 - 2oz layer first then 2 - 6oz layers. The first 2oz layer is so I don't get any cloth weave showing through. I've seen a couple glass kits made where the first layer is the 6oz and in certain angles you can see the weave.
Old 07-16-2002, 01:05 AM
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Default glass

I have the mold already. I did'nt know the # of layers I need to use. I'll give it a try this weekend, Thanks everybody for the help,
Edwin.

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