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 Post subject: Re: Carbon fiber lay up
PostPosted: Thu Apr 03, 2014 8:21 pm 
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Joined: Sun Feb 24, 2008 6:15 pm
Posts: 168
Location: France
TPink,
Any chance you can post some photos of your 1.2 k foil?
Did you vac sac it?
High mod carbon?
And what grade of balsa, where?
I considered this a possible building option but bailed for many reasons.
Seems to me that you are really pushing the moment of inertia concept to the max, hope it holds up.
How did you reinforce the connections?
I read a lot about balsa as a core and am most interested in your findings in real life flying your ultralight setup.
Thanx R H


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 Post subject: Re: Carbon fiber lay up
PostPosted: Thu Apr 03, 2014 10:15 pm 
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Joined: Tue Nov 09, 2010 10:00 pm
Posts: 73
revhed wrote:
TPink,
Any chance you can post some photos of your 1.2 k foil?
Did you vac sac it?
High mod carbon?
And what grade of balsa, where?
I considered this a possible building option but bailed for many reasons.
Seems to me that you are really pushing the moment of inertia concept to the max, hope it holds up.
How did you reinforce the connections?
I read a lot about balsa as a core and am most interested in your findings in real life flying your ultralight setup.
Thanx R H


having issues posting pics. do they have to be saved on a public server?


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 Post subject: Re: Carbon fiber lay up
PostPosted: Thu Apr 03, 2014 11:40 pm 
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Joined: Sun Feb 12, 2006 8:16 pm
Posts: 368
Location: Kettle Point Ontario Canada
Tpink you can email it too me and I'll load it for you ... will send you my email in a pm


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 Post subject: Re: Carbon fiber lay up
PostPosted: Fri Apr 04, 2014 12:28 am 
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Joined: Sun Feb 12, 2006 8:16 pm
Posts: 368
Location: Kettle Point Ontario Canada
ok here is a example of some cloth I have here
#1 8.9oz carbon
#2 2oz glass for surfboards
#3 is a glass/carbon hybrid... 21oz
#4 some of the crabon and glass I have on one rack... have 2 racks
#5,6 is 8.95oz black glass for under carbon if you just want a board to look pretty or can use it to make a black board ( hard to work with)

everything measured in mm. 0.00mm is my mic

so if you look at #1 and #5 you can see the difference in carbon and glass for the same weight of cloth

so 8.95 oz 8HS fiber glass is .16 thick.
5.8 oz carbon that is .5mm thick would be very loose weave and not really good for flex or twist.. just hard to picture carbon that thick and weight...

just my 2 cents..
Terrie


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 Post subject: Re: Carbon fiber lay up
PostPosted: Fri Apr 04, 2014 3:48 am 
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Joined: Mon Jul 01, 2013 7:16 am
Posts: 283
Location: Perth, Australia
Just to chime in,

if you guys can't find Paulownia wood than why not start a plantation? It is a fast growing timber and in 6 years time ready to saw I've been told.

Balsa was so cheap decades ago, ppl built surf boards with solid planks. But expensive today.

Paulownia is much stronger than balsa.


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 Post subject: Re: Carbon fiber lay up
PostPosted: Fri Apr 04, 2014 4:06 am 
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Joined: Sun Feb 12, 2006 8:16 pm
Posts: 368
Location: Kettle Point Ontario Canada
DU looked into it... I think there is a guy trying to get it started here... but when I looked into it they told me I was too far north to make it grow right. toooooo cold and to much snow in the winter... would be a great way to make money and help out with a fast growing renewable wood source...

I can get it from a suppler in cali. but cost of shipping and such ... just not worth it . cedar or bass wood is all around me. I can cut the tree down and take it to my friends to mill...
Image
Image

terrie
www.jellyfishboards.com


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 Post subject: Re: Carbon fiber lay up
PostPosted: Fri Apr 04, 2014 5:08 am 
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Joined: Tue Feb 05, 2008 7:34 pm
Posts: 7
Tpink,
Thanks, really good stuff. You make an excellent point of how important fiber orientation is for torsional strength. Having that mix of 0/90 and 45/45 might be more important than the epoxy you choose. The composite sandwich is an amazing structural element.
John


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 Post subject: Re: Carbon fiber lay up
PostPosted: Fri Apr 04, 2014 12:17 pm 
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Joined: Tue Nov 09, 2010 10:00 pm
Posts: 73
tkettle, thanks for the offer on the pix, I think i'm gonna shoot a short vid over the weekend and post it to utube.
that way I can talk and show at the same time, will be way better than a bunch of random pics.

I'll post the url as soon as its up.


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 Post subject: Re: Carbon fiber lay up
PostPosted: Fri Apr 04, 2014 1:20 pm 
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Joined: Sun Feb 24, 2008 6:15 pm
Posts: 168
Location: France
Nice tpink, we look forward to see your youtube vid.
By the way, every home made strut that I have seen that is stiff in flexion, bending along the long axis, and torsion, twist resistant, had plain weave, 0, 90,
and bi bias 45 ° AND uni dirctional CF. And almost solid with maybe a thin core.
You can find almost exact lay up info on the french forum.
We are now fairly sure that for all our home built vac sacked struts, fuses, wings that all 3 types of CF in the correct places are the best choice.
Just my thoughts, that is why I, we are most interested in your build!
R H


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 Post subject: Re: Carbon fiber lay up
PostPosted: Fri Apr 04, 2014 3:50 pm 
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Joined: Tue Nov 09, 2010 10:00 pm
Posts: 73
revhed wrote:
Nice tpink, we look forward to see your youtube vid.
By the way, every home made strut that I have seen that is stiff in flexion, bending along the long axis, and torsion, twist resistant, had plain weave, 0, 90,
and bi bias 45 ° AND uni dirctional CF. And almost solid with maybe a thin core.
You can find almost exact lay up info on the french forum.
We are now fairly sure that for all our home built vac sacked struts, fuses, wings that all 3 types of CF in the correct places are the best choice.
Just my thoughts, that is why I, we are most interested in your build!
R H


Thanks RH,
I'm determined to shoot/post the vid...

curious, is there a standard measurement process for struts to gage stiffness both lengthwise flex and tortional twist?
I've seen posted here somewhere where the strut was fixed to a wall and a certain amount of weight was hung off the end of the strut in configurations to measure both. But i'm not sure if that is a broader standard way of doing it.. If i knew, i would incorporate into my vid...


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