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Old Jul 18, 2008, 04:53 PM
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Reinforce fiberglass fuse: glass, kevlar, or CF?

Hi, I have an Electrostreak with fiberglass fuse. I have read that the wing saddle is weak and can use reinforcement. Also, I want to put a wheel in the center of the fuse to land on, which should be reinforced.

Should I use fiberglass cloth and resin, kevlar cloth and resin, or some kind of carbon fiber cloth? And any pointers to the kind of stuff I should use?

Many thanks....

Jim
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Old Jul 18, 2008, 05:38 PM
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I've used kevlar and cf and fg on some built up dlg's. Kevelar is very good for reinforcing small palces, (adding the wheel well), CF is good for long or larger areas.. pods,, along tops of spars (wind saddles on inside of fuse near the top of the saddle extending forwrd and back past the wing root). FG is good for all over strength.... Of course i'm no expert and this is advice is free...
Mike
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Old Jul 18, 2008, 07:41 PM
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Quote:
Originally Posted by Thermalin
I've used kevlar and cf and fg on some built up dlg's. Kevelar is very good for reinforcing small palces, (adding the wheel well), CF is good for long or larger areas.. pods,, along tops of spars (wind saddles on inside of fuse near the top of the saddle extending forwrd and back past the wing root). FG is good for all over strength.... Of course i'm no expert and this is advice is free...
Mike

Thanks....
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Old Jul 19, 2008, 07:15 AM
Will fly for food
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Kevlar is very strong, but not very stiff.

Carbon fiber is very stiff and pretty strong.

Fiberglass is reasonably stiff and strong.

So decide what characteristics you need.
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Old Jul 19, 2008, 09:35 AM
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Quote:
Originally Posted by Pinecone
Kevlar is very strong, but not very stiff.

Carbon fiber is very stiff and pretty strong.

Fiberglass is reasonably stiff and strong.

So decide what characteristics you need.


Thanks, just what I need. Since I want strong and stiff to protect the fiberglass fuse from cracking, carbon fiber sounds best. Is this an example of what I should buy? It's just like cloth, so it seems like any stiffness would come from the epoxy if I just use epoxy and this stuff. Should I use CA, or am I barking up the wrong tree with this product?
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Old Jul 20, 2008, 05:06 AM
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The stiffness comes from the fabric being trapped in some matrix. I would use epoxy in your application.

Clean and sand the area where you are putting the reinforcement. Apply cloth and resin, then use paper towels to remove excess resin. Too much resin makes the layup brittle and weak.
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Old Jul 20, 2008, 05:15 AM
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Quote:
Originally Posted by Pinecone
The stiffness comes from the fabric being trapped in some matrix. I would use epoxy in your application.

Clean and sand the area where you are putting the reinforcement. Apply cloth and resin, then use paper towels to remove excess resin. Too much resin makes the layup brittle and weak.

Thanks.....
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Old Jul 23, 2008, 12:55 AM
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where are you purchasing your CF cloth?
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Old Jul 23, 2008, 01:06 PM
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Originally Posted by mike early
where are you purchasing your CF cloth?

I have only looked online, but have not purchased. There are several places.

Jim
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Old Jul 23, 2008, 02:54 PM
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Would you mind providing a link or two?

I've searched, and am not sure what is what, really.
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Old Jul 23, 2008, 10:53 PM
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Quote:
Originally Posted by mike early
Would you mind providing a link or two?

I've searched, and am not sure what is what, really.

I didn't save any links, but all I did was google "carbon fiber cloth".

Jim
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Old Jul 23, 2008, 11:16 PM
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err, me too

But was hoping to gain some insight as to what weights, weaves, etc are best for our usages.
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Old Jul 24, 2008, 01:05 AM
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Originally Posted by mike early
err, me too

But was hoping to gain some insight as to what weights, weaves, etc are best for our usages.
Well, if I knew that I'd sure tell you, so maybe somebody else will say.
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Old Aug 03, 2008, 07:20 PM
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as far as weights go, i dont know the plane so i cant really help but i would imagine that you would want something 120-200gsm (grams per square meter).

to get a feel for the materials, carbon has a very high tensile strength, and will crack before the epoxy arround it, fiberglass cracks at about the same stress as the epoxy around it, and kevlar holds when the epoxy has cracked leaving "rope," if you are anticipating the area will need to flex use this.

there are sevseal types of weve you could use and all the diferencees are between them are how many directions of strength they have, plain weve cloth has 2 at 90 degrees to each other, twill weve has 3 set at 60 degrees to each other, for your application, at least the wing saddles, you might want to consider tow, which is a unidirectional (one direction of strength) set of fibres like an unwound rope. this is generally used for wing spars and reinforcement in the rc world.

for the u/c wheel you will want to make a "hard point" in the bottom of the fuse, i would use cloth for this, plain weve its cheaper and doesnt make much odds, and just place a square or circle arround where the wheel is to be attatched and add resin make sure all the cloth is wetted out (soaked up the resin), dab off any excess and leave to dry, the cloth should soak up most of the resin it needs for strength so if you lightly dab some kitchen towel or similar over the cloth this should take off any unnececary weight caused by the unreinforced resin. the wheel can then bolt through this.

if i were you i would go with a lighter weight cloth than you think you need, you can always add layers, much harder to take them off.

if you decide to use cloth you can lighly use spray adhesive before the resin so the cloth does not slip arround (any adhesive soaked up by the cloth will sap strength so you might want to do a test spray)

finally; good luck, hope this helps


cheers
julian
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Old Aug 04, 2008, 12:55 AM
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Julian, thanks for the excellent help, it's just what I needed. Which type of cloth would you choose for the hard spot on the bottom which will support the wheel?

Thanks again.
Jim


Quote:
Originally Posted by julian.i
as far as weights go, i dont know the plane so i cant really help but i would imagine that you would want something 120-200gsm (grams per square meter).

to get a feel for the materials, carbon has a very high tensile strength, and will crack before the epoxy arround it, fiberglass cracks at about the same stress as the epoxy around it, and kevlar holds when the epoxy has cracked leaving "rope," if you are anticipating the area will need to flex use this.

there are sevseal types of weve you could use and all the diferencees are between them are how many directions of strength they have, plain weve cloth has 2 at 90 degrees to each other, twill weve has 3 set at 60 degrees to each other, for your application, at least the wing saddles, you might want to consider tow, which is a unidirectional (one direction of strength) set of fibres like an unwound rope. this is generally used for wing spars and reinforcement in the rc world.

for the u/c wheel you will want to make a "hard point" in the bottom of the fuse, i would use cloth for this, plain weve its cheaper and doesnt make much odds, and just place a square or circle arround where the wheel is to be attatched and add resin make sure all the cloth is wetted out (soaked up the resin), dab off any excess and leave to dry, the cloth should soak up most of the resin it needs for strength so if you lightly dab some kitchen towel or similar over the cloth this should take off any unnececary weight caused by the unreinforced resin. the wheel can then bolt through this.

if i were you i would go with a lighter weight cloth than you think you need, you can always add layers, much harder to take them off.

if you decide to use cloth you can lighly use spray adhesive before the resin so the cloth does not slip arround (any adhesive soaked up by the cloth will sap strength so you might want to do a test spray)

finally; good luck, hope this helps


cheers
julian
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