Carbon Fiber

[Thelgord]

I am not sure if this is the right place for this, but here goes ...

Would be feasible to build the outer shell of a teardrop from carbon fiber? I realize it would probably cost a lot, just an idea I am thinking through.

[Shadow Catcher]

If you can build an airplane with carbon fiber or a canoe, you absolutely can. Had one friend who had a solo carbon fiber canoe on top of a Dodge Caravan and had an accident and ended with the van on its roof and the canoe underneath, it did not hurt the canoe other than being scuffed up.

[SLUG36]

it might make for a light and strong camper there. I think I had seen carbon fiber panels somewhere while surfing the internet a while back. I think it would look great in just raw form (not top coated)

[David_L6]

I am not sure if this is the right place for this, but here goes ...

Would be feasible to build the outer shell of a teardrop from carbon fiber? I realize it would probably cost a lot, just an idea I am thinking through.

Short answer: Yes.

It would be expensive though. My last two hydroplanes were built of carbon fiber with foam core. They were great boats but they cost half again as much as wood boats.

[absolutsnwbrdr]

Carbon fiber would make an awesome exterior! Lays just like fiberglass, but just much more expensive. My friend and I priced the carbon fiber fabric to wrap his 5x10 teardrop and if I recall correctly it was about 500 just for the cloth. We've never laid fiberglass before so we didn't even want to attempt the carbon fiber. If you have the skills and the money go for it!!!

[KCStudly]

If you can build an airplane with carbon fiber or a canoe...

...or a cello.

[aggie79]

You could but it would be a lot of work. Most likely you would need to make a plug, then a mold, and then your final parts. After polishing the exterior surfaces you'd have to apply automotive clear coat or some other finish to UV protect the carbon fiber and epoxy.

It would look cool but I don't know how practical it would be.

[Esteban]

I have never used carbon fiber. I understand it is much stronger than fiberglass cloth, harder to cut, and it costs considerably more. I wonder if it would reduce the need for "thick" plywood" Maybe to build a light weight teardrop you could use thin plywood, like 1/8", for the walls and roof. For a 5 x 10 that might save about 66 pounds to use 1/8" plywood instead of 1/4" plywood for the walls, roof and hatch.

If the floor is thinner plywood too that would save about 20 pounds for each 1/8" reduction of thickness you used.

Is carbon fiber any more difficult to lay up with epoxy than fiberglass cloth, other than initially cutting the carbon fiber cloth?

Some time ago I watched YouTubes about a man who made a foam and carbon fiber pick up truck camper top. If I remember right two people could lift the camper shell.

http://uscomposites.com/Discounted Carbon Fabrics has the best prices I know of. If you used 15 yards of their $22.50/yard carbon fabric for walls, the roof and galley it would cost $337.50 for the cloth. Expensive but not outrageously so.

The cost could be somewhat offset by substituting 1/8" luan at about $12/sheet compared to 1/4" plywood at about $30/sheet. If you use 8 sheets times an $18/sheet savings that brings down the plywood cost by $144. $337.50 minus $144 equals $193.50.

I estimate using fiberglass cloth instead would cost about $71.50. $193.50 minus $71.50 equals an additional cost of $122.00 to use carbon fiber instead of fiberglass in my scenario to save about 66 pounds for the walls, roof and hatch.

Worth it?

I'd like to be the second person to try this.

More weight could be saved with a thinner floor strengthened with carbon fiber. Maybe as much as 60 pounds if you used 1/4" plywood for the floor instead of 1/2" plywood AND used carbon fiber under your foam insulation instead of 1/8" plywood/luan.

Danger Will Rogers, this has me contemplating doing it.

You could save more weight by only using 1/8" plywood inside the cabin, foam insulation with minimal wood framing, and only epoxy/carbon fiber outside. Might save another 85 pounds or so.

66+60+85=211 potential pounds saved. I like it.

Edit: US Composites has a less costly 5.7 oz by 42" carbon fiber cloth for $14.50/yd for 10+ yard orders. That equals about $1.61/sq. ft. The $23.50/yd cloth is 50" wide so it costs about $1.95/sq. ft. $1.95-$1.61=$0.34. $0.34x9=$3.06/sq. yd. savings. So using this cloth might save an additional $63.00 or so for the walls, roof and hatch. Thus brings my scenario to use carbon fiber instead of fiberglass for a 5 x 10 teardrop to only cost about $60.00. Peanuts!

[Atomic77]

I'll chime in since I use Carbon Fiber almost every day, as I build and repair Unlimited Hydroplane's. As someone else here mentioned, you would need to build a mold. I know some people use plywood with fiberglass cloth over it. Which could be done with carbon fiber as well, but then again you really defeat the purpose of the strong, light weight material. So you would build a mold in sections...then join the sections. Also, the only way I do CF is to vacuum bag it. Here again, a very difficult task, not that it can't be done. It's just that bigger pieces are tricky and costly. In order to do it right, you need to build molds, do a lay-up schedule, you'll need release material and bagging material...West Systems resin epoxy and hardeners. Without the process, the finished product won't come out nice, even and clean. Honestly, it would look pretty cool and all...but unless you need a bullet-proof TD I'm thinking the expense really isn't justified. But then again...it's just time and money so what the heck! Go for it!

[Thelgord]

Wow! I knew there was a lot of knowledge on this site, but ... wow ....

All in all, I think the cost combined with my lack of experience with CF just puts it out of reach for me to do on my own. I have spent several days looking at how to work with carbon fiber and making even small pieces perfectly flat can be difficult. So for now, as cool as I think i would be, its just not in the cards. I really do appreciate the info though! Wo knows, maybe I inspired someone else to try it out

[michaelrsydney]

You don't need moulds if you plan to build in flat sheets. Carbon Fibre gives fantastic results when used as a skin material on both faces of a light cheap sheet material. Sheets of foam core material can be laid flat on a table and skinned with carbon/epoxy. Turn it over and do the same on the other side and you have a light, strong and very stiff panel. The panels can be cut to any shape and then either fastened to a frame or joined to other sheets just like fibreglass. Curved surfaces need to be bent before adding the carbon skin. The foam cores give the finished sheet good insulation qualities too.

The down side is that the material is expensive compared to glass and the resins are mostly nasty. The material is best applied using a vacuum bag system but it can be done without. Any supplier of carbon fibre and resin would be able to help specify the necessary materials.

[Atomic77]

Like I said, I do it every day. If you want a beautiful finished product, you'll need a mold or a vacuum or both, depending. Otherwise there will be grinding, sanding or some type of finishing necessary and again, that kind of defeats the purpose. You can lay it up without a mold or a vacuum bag...but trust me it will look like $#!%.

[Esteban]

I am confused. Which is not unusual. Is carbon fiber harder to use than fiberglass cloth on a flat level surface?

I built outside walls of 1/4" plywood that were glued and stapled to a 3/4" inner frame. I made a boo boo in my mix ratio of hardener to epoxy. My fiberglass stayed kind of "green" and did not fully harden. So, I used a heat gun and a drywall mud knife to remove the fiberglass from the plywood. Then I sanded the plywood which caused an uneven surface with highs and lows.

I mixed a new batch of epoxy and resin to fiberglass the wall a second time. Spread a couple of fill coats on it over several days. I then mixed epoxy/hardener and micro balloons to a paste consistency that I spread over the entire surface to fill in low spots.

After that I sanded the wall with an orbital sander to smooth the surface. I used a straight edge to find low spots and did some more filling and sanding until I was satisfied my surface was smooth enough.

It was a lot of work. The end results were good. If not for my "bad mix" it would have been much less work.

I go into all this detail because I wonder if I had gotten the epoxy/hardener mix ratio right if it would have been much/any different to use carbon fiber on a flat level plywood surface than to use fiberglass cloth in the same circumstances?

In my scenario in a prior post I made a thought experiment that using carbon fiber may not be much more costly than using fiberglass cloth if it allows you to use thinner, considerably lighter, less costly plywood. It could "shave off" a considerable amount of weight which would be good.

P.S. I planned to paint the outside so I had no need for the wall to look "beautiful" before it was painted. Strong, lighter than aluminum, water/weather proof, and a flat/smooth surface ready for marine paint was my goal.

[Atomic77]

Steve...
If your goal is to paint the finished product...The process is basically the same. The real issue is that sanding CF isn't the same as fiberglass cloth. It splinters and frays and is a real pain in the A$$. That is why we vacuum bag it and shoot for a perfect release that requires no sanding.

[Thelgord]

So, assuming you could get a perfect 1st time go with each piece, hard to do I realize, Would you do a shell as a single large piece? Or break it down to basic components (i.e.: walls, ceiling, flooring, etc...)?

How do you join two (or more) finished pieces of CF without a noticeable overlap/seem bulge? Would you use more CF? Or something else, such as rivets or special "joint" pieces?