Making a fuel tank

I'm pretty crafty so I'm able to make just about anything so I'm thinking a fuel tank couldn't be too hard. I have access to some K&S brass sheeting and I have some excellent solder and soldering equipment. Basically, figure out the bends and make an interlocking seam that could be soldered shut. For the ends make a hardwood block for a former and bend the sides down nipping a slight amount out so the corners lay down good...I'm making a rectangular tank. Burnish (sand) everything real good and get to soldering. Is there any trick to doing this or is it pretty simple?

Another question in as far as volume...1 oz = how many cubic inches?

BTW, I realize that Brodak will make custom tanks...yea, I bet they will...not very cheap either.

>Another question in as far as volume...1 oz = how many cubic
>inches?

One fluid ounce is 1.8046875 cubic inch

Roman Ramirez

Don't use brass for your tank material!

You'll be sorry!!

I have some Acme fuel tanks that are brass and they have worked just fine. The reason for not using brass is? ...and what material would be better? ...preferably something that can be easily found.

The primary reason for avoiding brass is weight. A brass tank of equivalent size/strength will weigh 25% - 35% more than an a tin-plated steel tank (of equivalent strength).

I have found that the tin plated stock (K&S) is significantly easier to solder and results in cleaner looking joints. The first two were .010 brass, the last three were tin.

There are good articles around on building tanks like the reprint in the '03 PAMPA newsletter. Most of them suggest the "time honored" method of using a buck or form block to shape the parts. I find it is easier to lay out the parts accurately using a Sharpie fine point marker, trim the flat pattern, and then fold using a home made seamer. I made three seamer sizes to create a standard wedge tank. The largest is wide enough to bend the tank sides (along length of tank), then one to do the long edge of the end caps, and finally a narrow one to do the short (wedge) sides of the end caps. Each seamer is simply a piece of hardwood (I used birch) about 8" long. I slit the end width-wise about 3" deep on a bandsaw and then bevel the ends at about 40 degrees into the slit. The angle allows for the springback of the material. You can slip the seamer over the metal up to your layout line (bend line) and use a small C-clamp to grip it. When everything is set perfect, just start bending! You can form the bend against a flat worktable to get it nice and crisp. If the parts are accurate and fit precisely, the solder job gets much easier! I prefer to make the two endcaps first and adjust the side dimensions for any "manufacturing variations."

If you use a form block to make the ends, don't use it to fold the side piece. Without a material allowance, they won't line up perfectly. I tried using a form block on my first tank. Since the material is so thin, I didn't think it would make much difference. It did on mine.

I make the tank sides a continuous piece of stock. I haven't had any problem with a simple lap seam on the back (inboard) face of the tank. I don't think you need an interlocking seam unless you are simply doing it for the challenge! (Or maybe you have some great sheetmetal tools in the garage....)

I recommend using lacquer thinner to clean the tanks thoroughly during assembly and afterwards. Alcohol and even acetone didn't seem to dissolve all of the rosin flux. (Resulted in buggers in my .049 needle valve. Not pretty on a 36,000 rpm engine....)

If you inexplicably seem to have soldering problems, try soldering some scraps. I thought I just wasn't getting the parts clean enough. The real problem was the soldering iron was not working very well. If you have a trigger operated soldering gun, give it away then go buy a soldering IRON with a tip that has a little mass to it. I got an 80W with something like a 1/4 diameter tip. It made all the difference in the world!

Be sure to pressure test. Soldering after having had fuel in the tank seems to be a lot harder, no matter how much flushing you do....

Now I just need to solve the solding reliability problem with the tubes. My vent line started leaking (again) last weekend and messed up a perfectly good flying day.... My flying buddies were kind enough not to laugh....

Just a few thoughts. Good luck with your custom tank!

Punch the holes, rather than drilling,

K&S makes pre-tinned material that is ready to solder.

Just use a gallon metal fuel can. I've made several, just sand the paint off with the Dremel tool. Works good and cheap.... recycle.

Ronnie

I've been making custom tanks for myself for years. Brass tends to harden in our fuel and then split. I always use copper tubing. I once took some brass and copper tubing and put them in 2 jars of fuel for about 6 months. The brass one broke when I tried to bend it, the copper one bent.
Another trick is to flush out the inside after you finish the tank. I used to use K&B Epoxy thinner, but dope thinner will do the trick too. I put about an once of thinner in the tank and let it set on each side for about 1/2 hour and then rotate the tank. If you look at what comes out, you will understand why. I like to use Radio Shack rosin core solder and a good hot gun, 250 Watt or higher.
Bill

Do you need a cheap supply of copper tubing? Talk to anyone working on gas appliances. They throw away thermocouples. They are made of 1/8th in coper tubing with an insulated inner wire. It is easy to remove the inner wire. They come in 12, 14, 18, and 24 inch lengths. You can bue new units for less than $5.00. Cheaper than K&S tubing. I have more than a lifetime supply from my work with a gas co.

If you check and some of the recent threads will find a discussion concerning the use of brass tubing in tanks.

It appears as if one of the constituents of the brass reacts with the Nitro (?) in our fuel and causes of brass to corrode. The corrosion is that green stuff that you find in your fuel lines after plane has been stored for while.

I just found that same corrosion in the fuel system of a plane that have been in storage for while. On the other hand, my tanks that have been built using tin for the tank and copper tubing have shown no ill effects caused by adverse reactions between the metals and the fuel constituents.

Nowadays I refrain from using brass sheets or tubing around glow fuel.

>I'm pretty crafty so I'm able to make just about anything so
>I'm thinking a fuel tank couldn't be too hard. I have
>access to some K&S brass sheeting and I have some excellent
>solder and soldering equipment. Basically, figure out the
>bends and make an interlocking seam that could be soldered
>shut. For the ends make a hardwood block for a former and
>bend the sides down nipping a slight amount out so the
>corners lay down good...I'm making a rectangular tank.
>Burnish (sand) everything real good and get to soldering.
>Is there any trick to doing this or is it pretty simple?
>

Back again, huh Gene?

Easiest way is to draw the pattern of the tank unfolded, and then stick the paper to the materal. Then cut/bend on the lines.

Don't use brass stock - use K&S "Easy Solder" tin (really, .007 tin-plated steel). No prep necessary, don't sand/wire brush it. Use rosin-core electronics solder with an electric soldering iron. Use copper tubing for the vent and feed tubes.

Use the K&S tin covered metal, it'a about .008 thick and bends very nicely over a wood form. I make at least four tanks a year this way. Use copper tubing, and punch the holes for the tubes with an awl. If you use a soldering gun like I do, Weller, loosen and retighten the lugs nuts that hold the actual tip in place. This gives a better contact. After a few hours with a gun, it tends to oxidize and insulate the tip. Use rosin core solder, not acid core.
If making a uniflow tank, be sure to solder the uniflow tube to the outlet tube about 3/8th of an inch from the end cap. Or a little less, but on the same plane as the feed tube.
The nice thing about making your own tanks, you know up front what they are like inside and can be tubed to fit your plane.

Back again, huh Gene?

Brett

Snip...

That's funny, seems like just yesterday I mentioned Gene in a post. In fact, it was yesterday. Imagine that...

I always solder a washer around each tube where it penetrates the tank. It will never leak if you do this, probably will, if you don't. Guess how I know. Steve

Steve...The washer idea sounds like a good one!

For everyone else...I went to my local ACE hardware store and got three sheets of K&S .008" tin and three sticks of K&S 1/8" copper tubing. It will probably be late next week before I can get to making the three tanks I need, but I'll let you know how I did.

THANKS for all of the help guys!

Steve,

Thanks for your timely suggestion! It's the first NEW idea I've heard in a while. Kinda obvious once you think about it! Now I have to go home, find some washers and fix my tank....