Question using Carbon Tissue.

Is any one using Carbon Tissue to cover fuselage and wings?

What do you use to apply it over balsa ?

Just to show me how well this material apply over contours, a friend applied with dope a small piece over a Dubro fuel tank. It did shape all the corners with a tight fit just using the brush. I was amased indeed.

But after it was dried, I removed the carbon tissue from the tank and when I pull to check for strenght it easyly teared apart, an it was also easy to rip it off.

Is this right?

What materials can we used to give super strenght on light built models?

Thank you,

Martin

That's what I would expect from carbon tissue.

>That's what I would expect from carbon tissue.

Ron B.
F4Fguy

Howard! Howard!

Carbon "tissue" is (usually) carbon veil. It can, when used properly add significant strength to a structure, and can also produce an excellent base for finishing. To answer the gentleman's question:

I've found that ,for applying CF for a finish base, the easiast way is to "Balsaright" the surface, then iron the CF on. Don't be dismayed by the relatively weak bond, you're not using it for strength, but for a hard, stable finish base. After 3 or 4 coats of dope, adhesion is definitely not a problem,and you can sand flat with almost no filler. As an aside here,If you are after increased skin strength, use finishing epoxy instead of dope (but be careful to squeegee most of it off).

I just used CFV for the first time on my Snark Rat. It added tremendous strength with little weight gain to the model. I also covered the rotor blades of my Kayaba gyro with CFV and they are a "stiff as a board". I gave the bare balsa two light coats of dope and a light sanding before covering with the CFV. It was tremendously easy to work with.

>I just used CFV for the first time on my Snark Rat. It added
>tremendous strength with little weight gain to the model. I
>also covered the rotor blades of my Kayaba gyro with CFV and
>they are a "stiff as a board". I gave the bare balsa two
>light coats of dope and a light sanding before covering with
>the CFV. It was tremendously easy to work with.

Did you use Dope over the CFV ?

I am confused, is Carbon Fiber Tissue used just to get a better finish the lightest possible way or to add strenght to the structure in lightest way possible?

>>I just used CFV for the first time on my Snark Rat. It added
>>tremendous strength with little weight gain to the model. I
>>also covered the rotor blades of my Kayaba gyro with CFV and
>>they are a "stiff as a board". I gave the bare balsa two
>>light coats of dope and a light sanding before covering with
>>the CFV. It was tremendously easy to work with. :7
>
>Did you use Dope over the CFV ?
>
>I am confused, is Carbon Fiber Tissue used just to get a
>better finish the lightest possible way or to add strenght
>to the structure in lightest way possible?
>
>Martin

Ron B.
F4Fguy

Martin:

There is, arguably, some stiffening to be gained from CF veil using dope as an adhesive, but the primary advantage is in hardening the surface for a flatter, lighter finish. To gain any significant strength benifit from the carbon fiber, you need a high strength adhesive such as epoxy or CA.

I simply used clear dope thinned 50% to appy the tissue. The top and bottom of my Rat Racer fuselage is sheeted with light 1/16" balsa. I was concerned about possibly putting my fingers through the sheeting without the tissue but not anymore. The tissue ads a considerable amount of stiffness and therefore in my humble opinion significant extra strength against punctures. The rotor blades of my Kayaba now have very little flex to them. I'm not certain whether that will be good or bad but I'll eventually find out.

Ron B.
F4Fguy

It's all a matter of degree. Significant? "The eye of the beholder".

Ron B.

P.S. Been there, done the tests.

Well I got the CFV and unfortunately I had serious problems with it.

I bought .2 for the wing and .5 for the fuselage from LoneStar Models. Applied 3 hands of dope, and light sanded. Then Applied the CFV using 40% Dope 60% Thiner, applied 2 hands and on the third one a little thicker then that.

Unfortuanatelly the results were not good. The CFV did not seal no matter the amount of Dope and Sanding.

I cover the model with one coat of primer, fine sanded and painted with polyester paint. It seems the veil worked like a sponge.

Finish was porous and in some areas of the leading edges it form empty pockets and then cracked.

I sanded over the painting, apply a new coat of primer and then painted again. It got better, but results were not nice.

Did I do something wrong or the problem was with the quality of the CFV that I got?

LAST EDITED ON Jun-10-06 AT 05:07 AM (CST)
 
I believe your error was in using way to thin an application of dope in applying the CFV to begin with. Apply it with nitrate dope. Butyrate sometimes has a problem sticking to itself as you described. After the first couple overcoats and sanding then go to
Butyrate. The material itself is very porous and will benefit from a good stiff coat to apply it. No need to thin any coat that much as the dope itself will easily penetrate the natural porosity of the CFV. You will not have these problems.
Paper tissue has to be applied with well thinnned dope because it needs to be thin to penetrate the tissue so it will stick.

LAST EDITED ON Jun-10-06 AT 10:52 AM (CST)
 
>
>Well I got the CFV and unfortunately I had serious problems
>with it.
>
>I bought .2 for the wing and .5 for the fuselage from
>LoneStar Models. Applied 3 hands of dope, and light sanded.
>Then Applied the CFV using 40% Dope 60% Thiner, applied 2
>hands and on the third one a little thicker then that.
>
>Unfortuanatelly the results were not good. The CFV did not
>seal no matter the amount of Dope and Sanding.
>
>I cover the model with one coat of primer, fine sanded and
>painted with polyester paint. It seems the veil worked like
>a sponge.
>
>Finish was porous and in some areas of the leading edges it
>form empty pockets and then cracked.
>
>I sanded over the painting, apply a new coat of primer and
>then painted again. It got better, but results were not
>nice.
>
>Did I do something wrong or the problem was with the quality
>of the CFV that I got?

Martin, is this a fully sheeted structure, or an open framework? I don't think I've seen anyone post that they've tried it on an open framework (other than just covering the solid parts, such as capstrips).

Wondering if Polycrylic would work here instead of nitrate dope..
2-3 years ago (check the archives), it was the Magic Elixir of Stunt.

>>
>>Well I got the CFV and unfortunately I had serious problems
>>with it.
>>
>>I bought .2 for the wing and .5 for the fuselage from
>>LoneStar Models. Applied 3 hands of dope, and light sanded.
>>Then Applied the CFV using 40% Dope 60% Thiner, applied 2
>>hands and on the third one a little thicker then that.
>>
>>Unfortuanatelly the results were not good. The CFV did not
>>seal no matter the amount of Dope and Sanding.
>>
>>I cover the model with one coat of primer, fine sanded and
>>painted with polyester paint. It seems the veil worked like
>>a sponge.
>>
>>Finish was porous and in some areas of the leading edges it
>>form empty pockets and then cracked.
>>
>>I sanded over the painting, apply a new coat of primer and
>>then painted again. It got better, but results were not
>>nice.
>>
>>Did I do something wrong or the problem was with the quality
>>of the CFV that I got?
>
>Martin, is this a fully sheeted structure, or an open
>framework? I don't think I've seen anyone post that they've
>tried it on an open framework (other than just covering the
>solid parts, such as capstrips).
>
>Wondering if Polycrylic would work here instead of nitrate
>dope..
>2-3 years ago (check the archives), it was the Magic Elixir
>of Stunt.

Fully Sheeted wing and Fuselage.

>QUOTE:
>But after it was dried, I removed the carbon tissue from the
>tank and when I pull to check for strenght it easyly teared
>apart, an it was also easy to rip it off.
>
>Is this right?

For what it is worth: If/when you apply the veil with epoxy resin, you have to give the stuff a chance to harden to full strength.

The sort of stressing/loading you describe is called "peeling". This is the most difficult load you can apply to any laminate.So, before testing , wait a week at least or let the product cure in an oven at say 100 deg.centigrade for a night.

LAST EDITED ON Jun-12-06 AT 02:59 PM (CST)
 
Here's what I'm doing, right or wrong...and a potential answer to your problem.

Two to three coats of nitrate sanded smooth. Apply LIGHTWEIGHT (.2) CF with brush and nitrate. Smooth out with your fingers. When applied it should have a "hairy" (not fuzzy) appearance with fibers running all through it. Kind of looks like heavy silkspan. Now, I recently ordered a new supply and applied to the same airframe. This material laid out with a very flat solid black look to it. No visable fibers at all! I put a couple more coats of thinned nitrate over the model laced with zinc sterate for filler. Well, guess what? The old fiberous CF sealed almost immediately. The new solid black stuff was full of pinholes! I also noticed that the new black stuff didn't conform to the curves of the airframe as well either. Seems to me that it was Brett B. also had the same complaint on this forum. Anyone else?

The old fiberous CF sealed almost immediately.
>The new solid black stuff was full of pinholes! I also
>noticed that the new black stuff didn't conform to the
>curves of the airframe as well either. Seems to me that it
>was Brett B. also had the same complaint on this forum.
>Anyone else?

Everyone else who used the more uniform, stiffer, CF got that problem. The difference is the amount and maybe the formula for the sizing used to hold the fibers together.

BTW, I think that I know how to fix it if you are not too far along. Mix up some polyester filling compound (Hobbypoxy PFC, or something else like Bondo), and trowel it on with a flat applicator. Get it in the holes, but try to minimize the amount that remains on the surface. Then sand it down level and paint over it.

No guarantees, but I think this will work.

Well the airplane is finished and painted. I sanded the first coat of paint, then applied primer to fill the holes and smooth the sponge like finish, fine sanded and painted again. The results were not perfect, but it ended nice. I had to finish this project by Jun 9th, to get the sponsorship to go to the NATS and I had to hurry. Otherwise I would have send it down to the wood and start all over!

I concluded that the problem was with the quality of the CFV that I got from LoneStar Models. As a matter of fact I also didn't like the quality of the 1/16x4 sheets for wing sheeting I got from them as well, in some points of the wing it got all wavy. I send an email about the problems and they didn't bother to reply.

On another post about Carbon Fiber Mat there was references about two kinds of MAT with different properties and that the best place to get them was from AeroSpace http://www.acp-composites.com

On my next project I will try the material from them and if I use Dope I will make it more concentrate.