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Old Jan 26, 2007, 09:23 PM
Detail Freak
target's Avatar
Harbor City, CA
Joined Oct 2003
21,472 Posts
Mini-HowTo
Ballast tube 101

I decided to do a ballast tube how-to, for the guys who may not know how...
Here's how I do it:

First I decide what the dimensions of the tube will be. I usually buy tubing from either copper or brass, that I will use as jacket for the lead slugs, and just use that to form the fiberglass tube.
For this one, though, I'm making it to size for a friend that has his own slugs already. Each slug is 3/4" diameter, and 2" long. There will be nine slugs, so the tube has to be over 18", to account for the plug at the back of the tube, and an anchoring method in front.

So, I'm going to be making a tube greater than 20" long, with an ID of slightly over 3/4", so that the slugs won't get stuck.

I'll be using:

24" x 3/4" round pipe or rod to form the tube,
Masking paper,
"Zagi" tape,
Masking tape,
4 oz S-fiberglass,
West Systems #105 resin with # 206 hardener,
Mixing cup,
Gram scale,
Stir stick and Acid brush,
Paper towels,
Gloves.

T
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Old Jan 26, 2007, 09:34 PM
Detail Freak
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Harbor City, CA
Joined Oct 2003
21,472 Posts
Here are the first pictures:

The paper size needs to be longer than the finished tube by a few inches.
Masking paper is easier to use than most other types, and you'll want at least 3 wraps of paper around your pipe, to help with the clearance between slugs and tube. If you cut the paper a little wider at the starting edge on the pipe, you can tape the corners, and get the paper on wrinkle free, which is what you want. A few small pieces of zagi tape will be useful for keeping the outer edge tight.

Next comes the tape job. Two lengths of black zagi tape is what I had to use on this one; a smaller diameter pipe may have only used one strip. You need to make the strips as long as the paper exposed. Dark zagi tape is best for doing this; it makes it easy to tell when the fiberglass is wet out later. Be very careful not to get any wrinkle in the tape. If you do, try slicing them carefully, to get them to lay flat.
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Last edited by target; Jun 10, 2007 at 09:58 AM.
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Old Jan 26, 2007, 09:40 PM
Registered User
oyazi's Avatar
Japan
Joined Feb 2005
258 Posts
Hello.target

It is very good.

oyazi.
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Old Jan 26, 2007, 09:43 PM
Detail Freak
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Harbor City, CA
Joined Oct 2003
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Thanks, oyazi!

You would have been proud of my Trinity last Sunday, it went VERY FAST!!!

Target
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Old Jan 26, 2007, 09:51 PM
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Carlsbad, California, United States
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Louie <<<<< Grabbing a beer watching the show.. Good Job T.
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Old Jan 26, 2007, 09:57 PM
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EZ Glider's Avatar
Santa Clarita, CA
Joined Nov 2005
710 Posts
ok T, my questions on a tube are which orientation do you use. Run it at the CG on the wing (in the wing), or lengthwise in the fuse. Seems like in the wing would be better especially in the event of a hard landing, but you re committed on CG. The fuse you could shift the CG with slugs, but if you have a rough landing Keeping the tube from destroying everything in front of it is an issue.

Jeff
Wo has an occasional rough landing
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Old Jan 26, 2007, 10:00 PM
Detail Freak
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Harbor City, CA
Joined Oct 2003
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Next, the fabric (4 oz. S-glass) is cut to make about 3-4 complete wraps aroud the pipe. Time for the high school math. (Pi x 3/4 x 3 wraps = 7.065") I cut the glass to about 8", so that I'd have more than 3 complete layers of glass. That should make a stout tube.

The glass gets sprayed with a light to medium coat on one side with (NEW, environmentally friendly formula) 3M77 spray. Let dry 5-10 minutes. Set the fabric flat on the work bench, and place the taped pipe on it towards one edge. I usually just roll the pipe back to the starting edge, and smooth that out with my hand. Then just roll and smooth the glass onto the pipe untill it is all on. If you get a bubble, don't wrap over it, just peel the glass off, and start over. Once it is all on, you are ready to mix resin.

T
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Old Jan 26, 2007, 10:04 PM
Detail Freak
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Harbor City, CA
Joined Oct 2003
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Quote:
Originally Posted by EZ Glider
ok T, my questions on a tube are which orientation do you use. Run it at the CG on the wing (in the wing), or lengthwise in the fuse. Seems like in the wing would be better especially in the event of a hard landing, but you re committed on CG. The fuse you could shift the CG with slugs, but if you have a rough landing Keeping the tube from destroying everything in front of it is an issue.

Jeff
Wo has an occasional rough landing

For most planes, the tube needs to be in the fuse, and you'll want to know the CG within a couple mm before you mount the ballast tube.
If you use 3M 5200 to mount the tube to the bottom of the fuse, it won't come out!
5200 is stronger than silicone and goop, but has just a little flex. So it's less likely to break out of there from shock, like you might encounter with epoxy...

That being said, the ballast tube in my Apex is in the wing center panel, and it's on the CG....Good thing the builder got that right the first time.

T
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Old Jan 26, 2007, 10:06 PM
Der Haifisch!! R.I.P.
BeeDee's Avatar
Fallbrook, California, United States
Joined Jul 2003
2,226 Posts
nice work T.. I have some aluminum tubes at work that I have been eying as a ballast system..

BD,
Aluminum tubes? You know what you can do with Aluminum tubes?
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Old Jan 26, 2007, 10:11 PM
PWP!
ajroahkni's Avatar
USA, HI, Makawao
Joined Oct 2002
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no waxing of the zagi tape required?
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Old Jan 26, 2007, 10:16 PM
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Carlsbad, California, United States
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Quote:
Originally Posted by target
The glass gets sprayed with a light to medium coat on one side with 3M77 spray. Let dry 5-10 minutes.
T


Attention Former Vice President Al Gore....
Note extreme violation of global polluting and global warming cause by said spray noted in project above by one TARGET. Send appropriate authorities to Targets house for immediate explusion of Target into outer space. Thank you. Sincerely, Deb D (Louied's wife)
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Old Jan 26, 2007, 10:27 PM
Detail Freak
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Harbor City, CA
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Now is the time for the resin. I mix more than I need, by a bit, and then I know I'll have enough. I planned on mixing up 24 grams total, but over poured while taking the picture.
I keep my resin and hardener in bottles with flip spouts, like shampoo bottles, for easy handling/measuring.

Mix the resin very well. Bubbles are no problem.
Place the tube over waxed paper, and pour a bead of resin on the fabric, don't worry if it runs off. Brush it in lightly. Concentrate on making all of the fabric dark, that means its wet out all the way through to the tape. Turn, pour, brush, repeat!

When you are all wet out, the tube will be very wet. It doesn't get stronger with more epoxy, just heavier, so now is time to take off excess epoxy. You can use paper towel, or toilet paper, but be careful not to disturb the fabric edge. Let dry.

You can see from what is left in the cup, I didn't use all the epoxy, and lots is in the paper towel and on the waxed paper. This particular tube should weigh no more than 1.5 oz when done. It's a large tube, and larger tubes need more glass, since they will carry more weight, than smaller tubes.
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Last edited by target; Jun 10, 2007 at 10:04 AM.
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Old Jan 26, 2007, 10:29 PM
Detail Freak
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Harbor City, CA
Joined Oct 2003
21,472 Posts
Quote:
Originally Posted by Louied
Attention Former Vice President Al Gore....
Note extreme violation of global polluting and global warming cause by said spray noted in project above by one TARGET. Send appropriate authorities to Targets house for immediate explusion of Target into outer space. Thank you. Sincerely, Deb D (Louied's wife)

Please refer to picture #1 in post # 7.... I used the "Globally Friendly" variety of 77 spray!
No need to apologize, simple cooking me dinner one night will suffice, Deb!
Love ya!
(You too, Louie)
Target
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Last edited by target; Jun 10, 2007 at 10:07 AM.
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Old Jan 26, 2007, 10:33 PM
Detail Freak
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Harbor City, CA
Joined Oct 2003
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Quote:
Originally Posted by ajroahkni
no waxing of the zagi tape required?

Zagi tape, I finally found a use for it!

Nope, no waxing necessary. Epoxy doesn't really stick to it. I have used it to make wing saddles (taping the underside of the wing), and little molds to hold my radio gear in my FREDY'S keel. It works great for this!
You of course know, that there is mold release already on the back of the tape, most tapes as a matter of fact... Sand the strapping tape on that super plank you're building after taping, before covering!

T
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Old Jan 26, 2007, 10:35 PM
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Carlsbad, California, United States
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Proceed please.
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