Aluminum Fuel Tank

[Martin Quartim]

Does any one makes uni-flow fuel tanks using aluminum sheeting and tubing?

Donīt remember ever seen a topic about this subject, perhaps there is a good reason not to make aluminum tanks, but I have been wondering why not an aluminum tank.

Martin

[phil myers]

Martin, I suspect its because aluminium (Aluminum your side of the atlantic!) is tricky to solder. Much easier with tin or brass..Phil

[Will Hinton]

And very little, if any, weight difference in something that size.

[Mike Greb]

I made an aluminium tank for one of my racing planes out of bar stock and used tetra fittings for the vent and feed tubes. A lot of work and a bit heavy.

[Brett Buck]

Does any one makes uni-flow fuel tanks using aluminum sheeting and tubing?

Donīt remember ever seen a topic about this subject, perhaps there is a good reason not to make aluminum tanks, but I have been wondering why not an aluminum tank.

  Yes, I built one one time, using the eutectic welding rod. It wasn't nearly worth the effort at the time, and now particularly so since you can get a much lighter carbon fiber tank.

      Brett

[Lauri Malila]

Hi Martin!

I made some tests and cannot see why it could not be done. But for one-off tanks it is not worth the efford. Also, you need wall thickness of minimum 2x thicness of steel sheet so there is no weight saving either.
For my tests, I just used some crap 0,5mm aluminium sheet from hardware store and Castolin Eutectic #190 braze. That castolin product is the best we have found for brazing mufflers, pipes, exhaust headers and such.
There were some problems:
 When brazing aluminium, the melting temperature of braze is very close to the melting temperature of alloy itself. And as aluminium is a good heat conductor, you must heat the whole object first and then concentrate heat to where you want the solder to run. That is especially difficult with thin walled objects.
Also, aluminium has quite high heat expansion coefficient. It tends to distort the parts during brazing.
Another thing is that "usual" alloys are very soft after brazing. You must look for an alloy that can be precipitation hardened afterwards. One such alloy, also with excellent brazeability, is #6262. I just don't know if you can get it in sheet form.
If I really had to do it, I would use #6262 or similar and just zap the parts together with laser and then do brazing in an oven, using brazing paste.
Another question is how aluminium tank reacts with fuel. Is there a bigger risk of corrosion?
Carbon tanks are nice but those I've seen are about 3x too big for my engine:)

Lauri

[Martin Quartim]

Thank you all for your comments.

Soldering aluminum is complicated but what about gluing the aluminum tank together? CF tanks are glued also.

The advantage of aluminum would be cost and I guess it would be easier to make.

I have 0.3mm aluminum sheet (general commercial grade) and my regular metal tanks are 0.24mm, so an all aluminum tank would weight half as much a regular tank. It would be less resistant, but I guess it would be strong enough, no?

I guess the only concern is how long the glue will resist fuel.

Other then JB weld what other glues could be used to make an aluminum tank?

Martin

[Lauri Malila]

I cannot find the link, but somewhere in internet Loet Wakkermann was explaining how he makes tank from balsa & alu foil. Basically he covers one (in-) side of balsa sheet with kitchen alu foil and then cuts parts and glues them together with cyano. They are strong enough for diesel combat, maybe that method could be improved for stunt use..? For example by covering the whole tank with glassfiber cloth.
But so far I trust tin tanks.

L

[Jim Kraft]

This has nothing to do with what you are talking about, but when I was about 10 years old I got a Half Pint race car and OK Cub .049 to power it with. It came with a piece of flat brass cut to fold into a tank to be soldered together. I got the tank all folded up but had no soldering iron or solder. What to do. Well, I had a woodburning tool and some plastic toys, so I melted plastic and sealed the tank together with that. I ran that car for a long time and the tank never leaked. Sometimes you just have to innovate.

[Larry Renger]

Besides, who needs it with an electric motor system?  

However, JB Weld should do the job, as would Goop Adhesive. Both are very fuel resistant. My Gooped together plastic tanks are good for a couple of years. 

[Howard Rush]

http://www.nclra.org/TechTopics/WayneTrivin/CompositeTanks.html is how to make carbon tanks.  Epon 862 resin is made to be impervious to chemicals.  It works lots better for fuel tanks than any other resin I tried.  I wouldn't use aluminum tubing in a carbon tank, but Wayne did, so maybe 862 can be used to glue alumin(i)um. 

[Steve Helmick]

http://www.nclra.org/TechTopics/WayneTrivin/CompositeTanks.html is how to make carbon tanks.  Epon 862 resin is made to be impervious to chemicals.  It works lots better for fuel tanks than any other resin I tried.  I wouldn't use aluminum tubing in a carbon tank, but Wayne did, so maybe 862 can be used to glue alumin(i)um. 

Is it possible to buy such small CF tubing, or would you make your own? Seriously.  Steve

[Randy Cuberly]

Is it possible to buy such small CF tubing, or would you make your own? Seriously.  Steve

Chemically, aluminum is an active surface.  The surface corrodes very quickly to aluminum oxide and glueing anything to this gives a fairly weak bond.  The rule in aerospace is to always anodize the aluminum if it is to be bonded to anything.  I think, if memory serves, the instruction sheet that comes with Epon 862 actually reccomends that any bonding done to aluminum alloys should be to anodized surfaces only!

Randy Cuberly

[Howard Rush]

Is it possible to buy such small CF tubing, or would you make your own? Seriously.

Any carbon tubing would have to have been made with resin that would hold up to fuel.  I considered using Central Hobbies pushrods or kite-shop stuff, but when I've cut it with a Dremel dangerous disk, it smelled like polyester.  Also, I think all the fibers run parallel to the hole, so it might split when the resin failed.  I used gold-plated copper tubing.  Seriously.

[pipemakermike]

Here is a link to how Mike Lewis ( a top UK combat flyer) makes glass fibre tanks for combat models.  Looks easy and would easily adapt to our needs.
http://combatflyers.co.uk/howto-glass1.htm

[Martin Quartim]

Again thank you all for your input. I will glue a few pieces of the aluminum sheet I have here with JB WELD I let it sit in small jar with fuel and see what happens.

If any one have some good ideas about this let us know.

Martin