ptulmer

My Feedback: (5)

Here's a pic of a tank I just got through cutting and bending. I lost the magazine I had with DB's article on these little tanks. Soooo... I need a little advice. Solder or braze? How do you put the lines into the tank? I'm not sure about just using fuel line over a brass tube.

WillieB

Solder works just dandy, but make sure you do a good job of it. it can be smoke tested or wet tested when you finish it.
I have used fuel lines on brass tubing for as far back as I can remember and never had a problem with it.

Good job.

Willie

ptulmer

My Feedback: (5)

It should be noted I'll be using this behind a VA. You don't think the tin will vibrate a cut into the fuel line and leak? (not the brass)

combatpigg

My Feedback: (3)

PATRICK, over in the ACHTUNG! WWI FOKKERBIPE! thread I showed my approach to tank building. For 1/2A, 3/32" brass tube works well, otherwise you can ice pick a hole in the tank and do a FUGI TANK type penetration for a flex line.

ptulmer

My Feedback: (5)

Son-of-a-biscuit-eater! I forgot about that. You soldered the tubes in. Mine don't look as good as yours, but hey!, I'm still a young'in compared to you.

combatpigg

My Feedback: (3)

LISSEN UP YOUNGUN! I got more time on a toilet seat than you got breathin air!You should have seen my first attempts at tank building...[:'(]! A few minutes of making sure your gaps are reduced to zero adds up to a better looking job and less weight. I use a round scribe to burnish the metal smooth after a cut, and the sharp end to poke holes with. Use weights to hold eveything in place and you need a powerful iron. Test the finished product with a clean solvent.

burtcs

I too make alot of my tanks. I use 0.005 brass shim stock, common resin core transistor solder works well and I use an 100 watt soldering gun to provide heat. I use 3/32 brass tube (sometimes 1/8) to hook up fuel lines. I use a scribe or awl to pierce the tank for the tubes insert and solder into place.

Before I cut metal I use a CAD program to generate the pattern for the tank. This pattern includes all flanges, When I've got exactly what I want I duplicate as may copies as will fit a 8 1/2 x 11" sheet of paper and then print out a sheet. Save the file and the sheet for future reference. Clean the shim stock with 000 (or finer steel wool). Glue the pattern to the shim stock with some glue stick (postem' type is best). When dry cut and bend the tank and flanges. I use common ordinary scissors for this. Then tack and solder together, this may take fifteen minutes and you've got exactly what you what. Just be sure to pressure check for leaks with a syringe.

A fire breathing TD will consume about 1CC every ten seconds, how long do you want to fly? The point I guess, is that it's not rocket science, good luck...

HTH - Steve B.

Jim Thomerson

You are better off to use copper rather than brass tubing. Brass tubing can spit, and corrode. Never a problem with copper. Having said that, there is brass and there is brass. I have some brass tubing and brass tanks which have done fine for many years. I would not take a chance with modern brass tubing; however, too many horror stories.

The way I test for leaks is to put the tank in the freezer for a couple of minutes, then seal it up and submerge it in hot water. If no bubbles, I consider it good to go. I check metal tanks every so often, and always if the engine run changes.

Jim

BMatthews

I punch my holes for the brass tubing with an awl like CP does. This forms a nice tulip shape depression around the tubing that holds a bit of solder for a more structural fit to the tubing. The cut ends of the brass is rather sharp but I run a fine cut file around it to take off the burrs. You can also use fine wet or dry sandpaper for the same thing but be sure to clean out any grit residue with a pipe cleaner through the tubing. Once the ends are de-burred this way you won't have any trouble with the silicone line splitting at all. I've heard of the brass cracking but it's never happened to me. However my longer tubes are often quite bent to I usually anneal the tubing by running it up to red hot with a propane torch first then cool it in water. After that it's soft as overdone pasta and will easily bend to any shape within reason. For longer tubes it's also wise to leave off an end cap on the tank and solder the ends of the longer tubes to the inside face of the sides and then finally solder on the end cap to seal it all. It's also a good idea to at least punch ONE tube hole in the tank before you seal it or the expanding and contracting air can make the last solder joint hard to do well.

ptulmer

My Feedback: (5)

Thanks guys. The first one is definitely ugly, but was tight. I used Jim's method of testing. It works very well. Found and sealed a leak where I missed soldering the first time. Turned out pretty nice.....except I left out the fuel line and clunk.[:'(][:'(][:'(] I've attached a pic of my layout. Instead of the way CP did it with the can and ends, mine can be cut out in a single piece. Think that's ok? It sealed well enough, but long term?

combatpigg

My Feedback: (3)

If EINSTEIN himself were alive today, he would have had a hard time coming up with a better tank pattern[8D]! Try this for a fuel tank, aluminum foil, 1/8" balsa sheet, 3M77, and CA glue. Contact cement the foil to the balsa sheet, cut the sheet into the tank side pieces and glue it together. Glue in your lines and you are done. I said,"NO WAY DUDE" when I first heard about this, but it is actually something that an approved design for "nostalgia diesel combat" plane features.

jboy381-RCU

would a balsa box fueled proofed with epoxy work???would it be to heavy???

john

combatpigg

My Feedback: (3)

The balsa box lined with epoxy might work, but would be prone to splitting. The foil liner gives the box sides a little more sheer strength. I have seen this idea used semi successfully, but after the first minor crash this plane was done for the day because the weight of the fuel [at 65 mph] did a number on itself and the wing was full of loose diesel fuel.

BMatthews

Maynard Hill experimented with epoxy coated balsa for tanks in his big duration models. I recall that he found a formula that worked but he also found a few that didn't.

I'll stick wth plastic thankyouverymuch....

gcb

Remember this was being used on diesels. Glow fuel has nitro which is a release agent for CA glue. You might want to substitute something else for the CA.

George

combatpigg

My Feedback: (3)

Over the years I've had a few ugly mishaps with tin and plastic too. In the right application a guy could stand to save some weight and space with an integral tank. If you were good about emptying the tank and maybe even purging it after a flying session I would think epoxy laminating resin might work. In my case where I'm branching off into FG models, this idea could bear some fruit?

johnvb-RCU

My Feedback: (1)

I did the balsa lined with epoxy, once. The tank was built into the airframe. Epoxy warmed up with a heat gun so it flows into the topless box, then more epoxy on the 'lid' and glue it down. Drill, carefully, holes for the pickup tubes and epoxy them in as well.

It's a diesel model, the tank hasn't leaked yet, but I suppose the only way I'd find out is if profilm starts lifting or the cabin fills with fuel. I don't have a good feeling about it and probably won't do it again.

vauxhall

I'm still making 'em out of styrene sheet and tube. Quick and easy, and NO soldering. I use Revell plastic kit glue. Thats for glo fuel, haven't tried 'em on my control line diesels yet, I've got a life time supply of tin c/l tanks from the "olden days".

ptulmer

My Feedback: (5)

Well, the second one turned out better. Still ugly, but I think I'm getting the hang of it. And this one has a fuel line and clunk in it!

Sticking it in the freezer for a few minutes then dunking in hot water is a most excellent way of testing for leaks!

XJet

It should be fine, a lot of turbine models, gokarts and aircraft have epoxy-fiberglass tanks and they stand up perfectly well to gasoline, Jet A1 and other minieral oil products.

They *don't* stand up too well to methanol however :-(

old git

Your tale reminds me of my first tank made fron a food can in the early fifties. I made it by forming the metal around a wooden plug, Unfortunately in my hurry to get soldering I left the wood in the tank. This was stupid but not critical. The real mistake came when I used short lengths of fuel tubing and plastic plugs/bungs to seal them. (The model was a power duration job) The idea was that when some fuel was used the vaccuum sealed tank would not allow fuel to flow and the the motor would stop. I tested lengths of fuel tube until I achieved a ten second run on the ground. In the excitement of the first flight I pushed the calibrated lengths of tubing too hard when I fitted the plug/bung and pressurised the fuel tank. The first flight was a success of sorts. The model climbed into the "wild blue yonder" and disappeared. I had omitted to light the D/T fuse and it was three days later that I got a phone call to say that my model had been found. It had apparently landed in a back garden surrounded by trees and settled, undamaged, on the compost heap.

I could probably have got a ten minute run from that tank.

johnvb-RCU

My Feedback: (1)

Thanks for the tips XJet.

All the best,
John