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 Post subject: Carbon fiber lay up
PostPosted: Wed Apr 02, 2014 5:03 pm 
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I need recommendations for the number of layers of 5.8oz. carbon
for front wing and strut. Lay up in a female mold. For the front wing
I would like a thickness of about 3/16 in. Do you use some glass as a
filler?


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 Post subject: Re: Carbon fiber lay up
PostPosted: Wed Apr 02, 2014 11:33 pm 
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Location: Kettle Point Ontario Canada
http://www.fastcomposites.ca/site/marin ... -measures/

5.8oz in general is only between .20-.25mm so it take 4 layers to get 1 mm give or take when epoxy is added 3/16" is almost 5mm so you would need 20 layers of carbon give or take.

3/16 isn't big enough for a mast of a foil ... 12mm-15 mm if you are pressing it. Maybe the wing.. If you are asking this you don't really have a lot of back ground with epoxy work. I would try laying up a fiber glass one first to make sure you have everything worked out..

Next thing is what kind of carbon? There are many types of carbon... the best to use is HM (high modular) but with HM it has a higher cost ) you need 3-4 different kinds of carbon to make a foil work and be strong enough to not flex or twist. then the epoxy is the next step...all will work but some will work a lot better then others. Are you baking the foils after wards to post cure it? or are you curing it as it is being pressed? Both ways have different steps.

do a lot of reading and research before wasting your money on high end carbon and epoxy... I would start with a wooden foil and go from there ,,

just my 2 cents and would rather see you get it done and be happy then waste money and be made.

Terrie
www.jellyfishboards.com


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 Post subject: Re: Carbon fiber lay up
PostPosted: Thu Apr 03, 2014 3:43 am 
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Thanks for the reply, Terrie. I'm sorry I was not more clear in what I was asking. I'm actually only interested in hearing from someone who has actually made a successful front wing and the specific layup they used. As you pointed out, carbon is expensive, and I was trying to minimize test layups. I've been building high performance composite "toys" for over forty years, for fun. I can assure you that a non tempered good layup using consumer epoxy and carbon is far superior to a piece of plywood with a layer of E glass. After all, these are only high performance toys, not aircraft.
John


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 Post subject: Re: Carbon fiber lay up
PostPosted: Thu Apr 03, 2014 4:20 am 
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Well then JAW show us your airplanes (or what have you), since you're here!
And by the way I hope you speak French, many answers to your questions can be found in that language @ http://kitefoil.forumactif.org/
But finally it's all a bit empirical, sounds like your guesstimates would be better than mine, so that's all I'll say now since I haven't built one yet.


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 Post subject: Re: Carbon fiber lay up
PostPosted: Thu Apr 03, 2014 8:23 am 
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JAW wrote:
Thanks for the reply, Terrie. I'm sorry I was not more clear in what I was asking. I'm actually only interested in hearing from someone who has actually made a successful front wing and the specific layup they used. As you pointed out, carbon is expensive, and I was trying to minimize test layups. I've been building high performance composite "toys" for over forty years, for fun. I can assure you that a non tempered good layup using consumer epoxy and carbon is far superior to a piece of plywood with a layer of E glass. After all, these are only high performance toys, not aircraft.
John


Maybe I am reading this wrong but your attitude is a little stinky.

Terrie knows an awful lot and with the info you gave his response was a good one.


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 Post subject: Re: Carbon fiber lay up
PostPosted: Thu Apr 03, 2014 11:39 am 
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Joined: Sun Feb 12, 2006 8:16 pm
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Location: Kettle Point Ontario Canada
I way just trying to help is all..

for lay up and if you have 40 years of epoxy work with glass you would know the thickness of glass and carbon... what is you end goal for thickness of mast? Are you using a mold or are you doing a core with a plexi and vacuum? There are too many question you are asking and not enough info.

the French foil forum is a great resource for someplace to start..
Frankie on there is one of the founders of diy foils and is very very good at building them
You will have to do some hunting but there are some specs on there for a starting point.

And who said that I wasn't working on a foil, you never know who is and isn't on this forum.

Terrie


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 Post subject: Re: Carbon fiber lay up
PostPosted: Thu Apr 03, 2014 2:09 pm 
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Sorry again. I really appreciate all the good people here who share their knowledge. Truly wonderful. I am afraid my bad attitude was only my frustration showing through of how difficult it is to get specific answers. My bad. This was my first attempt at participation here and my intensions are to share the excitement, enthusiasm, perhaps knowledge, and stoke on building a foil. I absolutely agree that there is no room for bad attitude here, only encouragement and sharing. I have searched the french forums, adding to the frustration when I can't read french. I have 1/2 of my main mold completed, the plug is based on air chair dimensions. It will be a wet layup in a female mold.


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 Post subject: Re: Carbon fiber lay up
PostPosted: Thu Apr 03, 2014 3:54 pm 
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I am going through the process of building a solid rear wing from carbon and shaping it afterwards.

I am using bound bi-directional 600g/m which I am finding very hard to wet out. As a test last night using only 3 layers to get an idea.

nice finish but very VERY flexible.


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 Post subject: Re: Carbon fiber lay up
PostPosted: Thu Apr 03, 2014 4:46 pm 
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Jaw,

I have just finished laying up my carbon foil and it came out great.

I respect tkettle's reply but don't necessarily agree.

First off, I used the 5.8 cf cloth as well. I just measured a piece of it holding it up to a mm ruler and a magnifying glass, and it is at least .5mm or more. certainly more than .2 mm.
Second, there is little value in a solid laminate piece, particularly if you want to acheive approx 10-13mm total. Mine (strut/front wing) came in at 12mm all up with final clear coat.

All modern layups for grand prix sailboats use a composite sandwich comprising and inner and outer skin covering a core of either some type of foam or wood (usually balsa). it is this method that gives you the stiffest and lightest part, Imagine an I beam.

CF is increadibly strong in tensil strength, meaning that it resists stretch along the bias of the threads. To achieve stiffness along the length of a piece, you need to have the opposing skins of the part resiting the forces that want to bend it. That can be achieved by a pure carbon part, but it is only the outside layers of carbon that are acting to resist the bending forces, meaning the inner layers are unnecessary, and heavy.

My strut and wing have a balsa core of say 9mm, 3 layers of CF on each side, totalling 6 layers.
Of the 3 on each side, 2 are oriented 0/90 bias to the part, 1 is 45/45. This provides ample stiffness along the part and torsionally to prevent twisting.
I mean to tell you, i can not grab both ends of my strut and either bend it along its length or twist it at all! and the all up weight of the entire foil (strut/frontwing/fuselage/rearwing) is 1.2 kg. !

My suggestion to you is to wax the molds with release wax, hit with one or two coats of clear, then lay up 3 layers of your 5.8CF, using the orientation i mentioned above. Then you could either fill each half with a foam or thin sheets of balsa & thickend epoxy to fill the center. That will produce the stiffest/lightest parts.

Good luck with it!


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 Post subject: Re: Carbon fiber lay up
PostPosted: Thu Apr 03, 2014 6:05 pm 
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Joined: Sun Feb 12, 2006 8:16 pm
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Location: Kettle Point Ontario Canada
Jaws I'll send you a pm tonight after work with what you are looking for...

google chrome will translates the French to English for you.. ;)

Tpink 12k 3k 24k carbon? they very in different thickness +- .05 mm. measuring with a ruler would be really hard to tell on a thickness. Just go to a carbon site for specs and look at the thickness of a 5.8oz cloth... twill , uni, biax, quadax they very... here is just one for just to see two different thickness
https://www.acpsales.com/Carbon-Fiber-W ... brics.html

look at the 5.6oz thickness of twill and plan weave... just the way the carbon is weaved it will make it different... .5mm is pretty thick with out resin for 5.8 oz.

I take some pictures tonight with a digital mic of a few different glass and carbon I have here

terrie


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