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Differences between good fiberglass, and good Carbon fiber.

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Patrick

Tue Aug 16 2011, 11:44PM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

2Spoons wrote ...

I bought some carbon/kevlar tube for my kayak paddle from here

They've got all sorts : glass, carbon , kevlar, basalt, and mixed materials. In cloth, tube, etc.

Ty, but what does pics per inch mean ? it says 17x17, is that the width of each weave?

In the above pic, each "strand bundle" of fibers is 0.040 inches wide, with the plain weave.

1/17 = 0.059" so this is a more coarse weave than what i already have.

Ash Small

Tue Aug 16 2011, 11:56PM

Registered Member #3414 Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245

I imagine you will probably want a carbon/kevlar mix eventually, but just stick with 'S' glass for now. (Fairly fine weave/low weight)

2Spoons

Wed Aug 17 2011, 01:28AM

Registered Member #2939 Joined: Fri Jun 25 2010, 04:25AM
Location:
Posts: 615

Patrick wrote ...

Ty, but what does pics per inch mean ? it says 17x17, is that the width of each weave?

In the above pic, each "strand bundle" of fibers is 0.040 inches wide, with the plain weave.

1/17 = 0.059" so this is a more coarse weave than what i already have.

A nice explanation from the same site

Ash Small

Wed Aug 17 2011, 11:17AM

Registered Member #3414 Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245

Some interesting reading here, including comparisons between E glass, S glass, carbon and kevlar:

Proud Mary

Wed Aug 17 2011, 11:37AM

Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992

Not so fast, Boy Wonder!

Fink BF, McCullough RL, Gillespie JW, Induction Heating of Carbon-Fiber Composites: Thermal Generation Model, Army Research Laboratory, ARL-TR-2261, September 2000.

EM interactions involving the carbon in carbon-fibre composites feature in a number of journal papers.

Patrick

Thu Aug 25 2011, 06:48AM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

Proud Mary wrote ...

Not so fast, Boy Wonder!

Fink BF, McCullough RL, Gillespie JW, Induction Heating of Carbon-Fiber Composites: Thermal Generation Model, Army Research Laboratory, ARL-TR-2261, September 2000.

EM interactions involving the carbon in carbon-fibre composites feature in a number of journal papers.

This is facinating!

Patrick

Sun Dec 18 2011, 06:16AM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

Ive broken a whole lot of Carbon fiber and fiber glass im now considering laying up my own CF, im reseaching this all-over again, any help is appreciated.

I see a lot on Ebay.

EDIT: im thinking of a Carbon Fiber/Kevlar mixed 3K fabric, 2X2 twill, and a -60, 0, +60 layer, 5.7 Oz., on balsa, with an epoxy wet lay-up.

Stiffness and strength are most desirable.

Im still trying to figure out the differences in the "K" numbers, i see 1,3,6,9,12,24K's but dont know what they mean in terms of strength/stiffness. iknow thats thethread count for bundles and that more strands means a thicker cloth.

Patrick

Mon Mar 19 2012, 04:18AM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

ok ive got 6 yards of S type fiberglass, and 3 yards of 644Ksi CF with a good hard epoxy coming in the mail.

ive researched a lot more, practiced laying up FG, im getting prettyt good at flat stuff. (and screwed up a whole lot too.)

ive got 2 savox digital servos, 2 castle 50 ice ESCs, and an AR6115e reciever, 2 eflite power 10's and a STM32VL and another STM32F4, 3 lipo's at 11.1volts, 2200mah.

im on my way to North Dakota IARC 2012!

Patrick

Tue Mar 20 2012, 08:56PM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

ok so the thickness of the 3 layer crap fiberglass is 0.029" and the balsa frame whieghs in at 61 grams, with the top layer of FG it now whieghs 230 grams, with 230 sq inches and 169 grams of FG that means 0.735 gams per sqare inch.

Dr. Slack

Wed Mar 21 2012, 08:00AM

Registered Member #72 Joined: Thu Feb 09 2006, 08:29AM
Location: UK St. Albans
Posts: 1659

If you're going for specific strength, that is strength to weight ratio, then one of the most important things is to use the right amount of resin. Too little, and the strength suffers, you risk delamination under load. Too much (and this is dead easy for the amateur who will tend to use "a bit more for luck", what people over 45 in the UK call the 'Enry Cooper Brut 33 effect) and the weight suffers.

Pre-pregs are more expensive than wet-lay, but tend to have just the right amount of resin on them (which is why people use them). Do consider vac-bagging.

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