Fuel Tank

General Composites Discussions Composites Talk
#1

I’m wanting to eventually get around to building a full composite fuel tank using carbon fiber and kevlar.

If you see on the inside of this fuel tank there is a clear coating of some sort. I’m not sure what type of resin they are using that is fuel safe?

Also is this internal hose an aircraft fuel hose? The outside and inside of that hose would always be in contact with fuel.

Any suggestions or ideas of the resin used?
http://s210.photobucket.com/albums/bb186/Fastrr_photos/?action=view&current=oppDucatifueltank.jpg

http://s210.photobucket.com/albums/bb186/Fastrr_photos/?action=view&current=oppDucatifueltank2.jpg

http://s210.photobucket.com/albums/bb186/Fastrr_photos/?action=view&current=oppDucatifueltank3.jpg

#2

some guy that built a one off fuel tank for his experimental aircraft used vinylester resin. he first tested composite laminate samples that were vinylester resin in three types of fuel… BP87, and then 91 octane of some other sort, and then 101octane jet fuel. after two years of submersion the resin showed no signs of failure.

Guess I can try vinylester for the resin.

edited b/c i just found this info online after my first post.

#3

Fastrr, i used to make the bay for a boat engine and we used vinyl ester which has some heat resistant characteristics. I cant remember the product number but it’s either from composite one or US composites. Ohh i just realized we’re talking about fuel here … nevermind then.

Btw, is that carbon fiber with silver color or a real aluminum fiber? I have some carbon/aluminum fiber hybrid in the freezer, but never got a chance to use it yet.

#4

There is no colored carbon fiber. There is however fiberglass coated with aluminum to make it silver.
And why do you have fabric in the freezer?

#5

Probably prepreg?

#6

Doubtful, as he says it’s “carbon/aluminum hybrid.”

#7

nice tank. very well done. i havent handled texalium, but if its stiff like black finish fiberglass (which i think it is) its gonnna be a bitch to shape

#8

yes it’s pre-pregs. I cant remember the name of the brand, something with Z in it.

tet, i couldve sworn ive seen those carbon fibers that have red, green or yellow in color in catalogs.

#9

Very interesting that you have those materials in a pre-preg. So you have an autoclave to cure it in?
The colored stuff was almost certainly dyed Kevlar, or possibly fiberglass.

#10

we dont have an autoclave. We outsourced it, but we do have a giant oven with thermocouple and everything in it. You can adjust the ramp rate and everything, pretty much like an autoclave except the pressure variability.

So you’re saying that carbon cant be dye with any color? why is that?

#11

To the best of my knowledge, you cant bleach coal.

#12

im not really satisfy with the answer but i guess i’ll take it at the face value. I just feel that with the technology that we have, im sure they can dye carbons with colors. And if they dye kevlar or fiberglass with color, dont they have to advertise that as carbon/kevlar or carbon/fiberglass instead of pure carbon? (maybe they do, but im just going with what i remember seeing in the catalogs).

#13

hahaha I my that got a laugh out of me… thanks JRL i really needed a good laugh :slight_smile:

The guys are correct there is no such animal as bleached or colored carbon fiber. hybrid is usually colored kevlar woven together with carbon fiber.

#14

I don’t think carbon can even hold a color and if it did you wouldn’t be able to see it because the carbon would overwhelm the color. If you want a single color nice weave you would have to buy kevlar and then dye it or be lucky enough to find it pre-dyed.

#15

Fastrr,
Have you looked into fuel tank sealers? I used them when making fuel surge tanks out of steel to prevent internal rusting. Maybe you can coat the inside after the part has cured, I don’t know how well it would bond to a resin surface though.

#16

Rezcar I did think about that. I believe POR company makes one called POR15 or something like that. I’m not sure if those would bond or not, but you bring up a good point.

#17

you can dye carbon, it can only be dyed darker colors and it is 3 times the price of kevlar. That is why the technology never went really any further because you can dye kevlar for the same price as if normal carbon anymore. I have been in contact with a customer that has talked with torray and they have told him about colored carbon but again it was only dark colors and when you wet it out it pretty much looks black again

#18

there is silver kevlar hybrid, I have some prepreg of it too left over from a project a couple months ago

#19

i think i want to try and find some black kevlar to back up my parts with on the final laminate layer.

what type of dye do you use to color the kevlar? or do composite workers mix the dye into the resin when laying up the part? If that would work, i have black epoxy dye.