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Help IDing CF vs Fiberglass?

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MattJL

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The other day, I was generously donated some spare 4" body tubes (and one coupler) for building an L1/L2 bird. However, I'm not entirely sure what they're made of, and because they're black, they don't photograph too well.

Things I know:
  • They're from Madcow Rocketry.
  • They're 60" long and 4" across, don't know the wall thickness offhand.
  • They're reasonably light for their size, somewhat moreso than fiberglass?
  • They have a distinct diamond-shaped weave to them, something I've never seen on fiberglass before.
I can try and post pictures tomorrow if it would help any. I don't think they'll be too helpful.

On an unrelated note - does anyone know why all 4" body tubes are out of on stock Madcow's site? There seems to be a general shortage of 4" tubes to begin with.
 

rharshberger

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If they look like this then most likely they are carbon fiber (the black section). Madcow does list a weight per foot on his website so you may be able to identify the tubes by weight. Filament wound carbon fiber has a different look than the handlaid (my picture which is twill) parts, Madcow also has some good pictures to give an idea of what CF vs FG would look like.

GLRNuclearSledgehammer58.jpg
 
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Reinhard

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Black profusion tubing and carbon fiber look reasonable close at first. Compared to each other, the carbon fiber on the surface, where it is ground, looks more shiny with kind of metallic looking luster.

A clear difference can be seen in the sanding dust. The FG tubing will generate white dust, even if the tubing was black in appearance, whereas the CF dust will be black. If you don't want to scruff up the outer surface, just put a piece of paper on the table and put an end of the tubing on it and rotate it back and forth a bit, as if you were cleaning up the the edge after a cut.

Reinhard
 

Bat-mite

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Filament-wound fiberglass (FWFG) is duller and looks swirly. Carbon fiber (CF) is shiny and has diagonals through it.

Madcow makes only five CF kits, ranging from 1.1" tubing to 4" tubing; but they make a ton of FWFG kits, and most are available in a choice of colors, including black. So if I were drawing straws, I'd expect FWFG.
 

MattJL

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Thanks for the feedback, everyone! I just ran a couple tests on it, and I'm 90% sure that this is carbon fiber.

The weave is a little hard to see, but going off of what everyone's told me, that's a dead giveaway for CF. And a fingerful of dust, though it looks white against the body tube, is black on a piece of paper.

Anyone know what nosecones are compatible with this particular tube?
 

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catman001

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A easy way to tell for sure is by weight. The Madcow website states a weight of 12.8 oz per foot for their G12 4" tubing and a weight of 8.4 oz for the carbon fiber. For a 5 foot section that is 64 oz vs 42 oz. Easy to tell with a scale. Both the G12 and carbon fiber tubes have a I.D. of 3.900 inches. Either the filament wound or the standard fiberglass nosecones from Madcow should fit.

P.S. If the tube is carbon fiber that is almost $300. Nice friend, think I would buy him a few beers.
 

MattJL

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A easy way to tell for sure is by weight. The Madcow website states a weight of 12.8 oz per foot for their G12 4" tubing and a weight of 8.4 oz for the carbon fiber. For a 5 foot section that is 64 oz vs 42 oz. Easy to tell with a scale. Both the G12 and carbon fiber tubes have a I.D. of 3.900 inches. Either the filament wound or the standard fiberglass nosecones from Madcow should fit.

P.S. If the tube is carbon fiber that is almost $300. Nice friend, think I would buy him a few beers.
Good to hear that the nosecones are standard. I'm a little apprehensive about working with CF, since the most experience I can draw on revolves around G12, but I don't imagine they'll be too different. Hopefully it takes paint OK.

I definitely owe him one - he's a great friend, not just for the CF.
 

Maxwelljets

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It might just be the picture, but to me that definitely looks a lot more like black glass than carbon. The comment about black dust vs white dust is a bit misleading. Black glass dust looks kinda grayish, but carbon is just black. I'm talking charcoal black. Dust from black fiberglass tube would definitely look dark gray on paper.

The main thing about the picture that leads me to believe it's black glass is that carbon is black everywhere, whereas black glass has black dye exclusively in the matrix. This tube is a bit splotchy looking, and the more fibery spots are much lighter in color than the splotches.
 

MattJL

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It might just be the picture, but to me that definitely looks a lot more like black glass than carbon. The comment about black dust vs white dust is a bit misleading. Black glass dust looks kinda grayish, but carbon is just black. I'm talking charcoal black. Dust from black fiberglass tube would definitely look dark gray on paper.

The main thing about the picture that leads me to believe it's black glass is that carbon is black everywhere, whereas black glass has black dye exclusively in the matrix. This tube is a bit splotchy looking, and the more fibery spots are much lighter in color than the splotches.
Yeah, it's not particularly glossy. The weave is what throws me off here - it looks a lot like what I've been told the CF weave would look like, but the whole airframe's just covered in dust from wherever it was stored. I took a picture of my dust-smear test, too. It looks a little gray-ish, now that you mention it.
 

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Maxwelljets

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Yeah, I'm gonna say that's definitely black glass. Like I mentioned earlier, carbon dust is just black. There's no arguing over whether it's gray or black. It looks like charcoal dust or lampblack, because that's essentially what it is. It's black enough that when I've sanded it with black sandpaper, the sandpaper is darker where the carbon was.
 

MattJL

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Yeah, I'm gonna say that's definitely black glass. Like I mentioned earlier, carbon dust is just black. There's no arguing over whether it's gray or black. It looks like charcoal dust or lampblack, because that's essentially what it is. It's black enough that when I've sanded it with black sandpaper, the sandpaper is darker where the carbon was.
That's a fair call. My enthusiasm is not dampened - in fact, I'm kind of glad that I don't have to scrap the paint scheme I have in mind (if it was CF, I'd prefer to finish with just a clear coat).
 
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