metal fuel tank

[DA Miller]

I'm building a metal fuel tank and would like to use std bathroom fixtures for the filler tube and cap, but I'm having a problem selecting the pieces. Any help would be appreciated.  Also once the pieces are selected how are they attached to the tank?  I need some help with this.

[Terry Lundby]

Here is a link to a great site, much information here. https://bobhooversblog.blogspot.com/2006/12/av-yo-fuel-tank.html?m=1
Look up Tony Bingelis on the EAA site. He wrote about the nuts and bolts of AC.
If you're going to go to a metal tank learn about NPT fittings and AN hardware. A leaky gas tank is not a pleasant idea.
Best regards 
Terry.

[GTS225]

Will the tank be steel or aluminum?  Most household plumbing fittings are brass, so you could braze that to steel, but not to aluminum.

Personally, I have to agree with Terry....a gas leak of any kind is NOT a good thing.

Roger

[DA Miller]

This is dthe 3rd time I've tried to reply! Somehow I* hit a wrong key and it all disappears. So I'll make it short and sweet: I'm familiar with the Hoover blog.  I'm also fairly familiar with the blue AN HW. It's an Al tank. I searched Lowe's to day for a 11/2"d metal pipe with threads on one end. NO METAL PIPE.  Found TWO PLASTIC PIPES AND CAPS THAT MIGHT WORK if I can figure out how to attach a flange to the end. will try some of these new glues.  Tanks again,  Possum

[GTS225]

PVC is not a good thing......gasoline will break it down over time.
You might want to take a look at electrical conduit.  There are threaded hubs or flanges that bolt onto a service panel, and they are sized in 1-1/2" pipe thread (plus other sizes).  A bonus is that they're aluminum.  If you combine that with an "IMC" conduit nipple and cap, that might do what you want with little weight penalty.  I can not say how it might be to weld it, though.

Just brainstorming.....Roger

[DA Miller]

Thanks for the heads up on the pvc and gasoline. I"ll take a look at the conduit. I did find a 6" x 1 1/2" pipe with threads on the end and a nut at my local ACE hw. Also a 4 x 8" x 0.032"brass sheet. If I can braze a brass flange on the pipe I'll be in good shape

[TezzaT]

Hi DA, I purchased mine from this outfit on Aliexpress. Aluminium weld in fuel cap & tube! worked great. Just had to tap 1/8 NPT for a breather fitting. Available in several sizes,
Terry. XL now flying.

https://www.aliexpress.com/store/832242?spm=a2g0o.store_pc_home.pcShopHead_11132524.0

[DA Miller]

Hey TezzaT, thanks for the input, but I think I have mine worked out.  I'm going to solder a brass flange to the 6" pipe and cut a matching AL flange for inside the tank.   I'll shorten the 6" pipe. Then rivet the three together. It will be AL flange, Tank top, brass flange.

[BobbyBreadwinner]

DAMiller,

You asked about how I did my tank... hijacking my avionics SimpleFly thread. 

Looking on my build log, I did not make a single note about it! So...

My Legal Eagle tank is aluminum, five gallons, in the left wing per plans. It was fabricated out of 0.050" 5052 and was TIG welded. The filler is a billet weld-on bung and cap. Amazon, Summit Racing, not sure. For a vent I simply drilled a small hole in the cap. I fabricated a small sump (maybe 2"x2"x2") near the rear of the tank which extends down below the bottom surface of the wing. You might be able to see it in one of the pictures. On the bottom of the sump is a drain plug, and on the side of the sump, running horizontal and forward, is a 1/4 turn valve with an AN fitting. Aluminum fuel tubing down to the engine held along the fuselage tubes with Adel clamps.

The total weight of the tank was 3.3 pounds (I individually weighed everything on this build, I am detailed like that). As I recall, this was about half the weight of the rotomolded plastic one used on the Mini-Max.

I had to get very good at TIG welding for this tank. I am no pro, but now one of the better welders at the EAA chapter. This was some of the most difficult welding I have done. I also failed at welding a tank when working on my Thatcher CX4. If you want to see that mess it is here:

https://worktablecnc.us/projects/thatcher-cx4.html#fuel-tank

Robert (BobbyBreadwinner)
Oregon, USA

[DA Miller]

Bobby, thanks for your reply.  My tank  will be riveted and pro-sealed since I have no tig welding experience.

[Dan_]

Bobby, thanks for your reply.  My tank  will be riveted and pro-sealed since I have no tig welding experience.

DA,
Tips for the proseal job...

https://www.kitplanes.com/adventures-in-pro-seal/

[DA Miller]

Dan,  thanks I'll look at this tonight. Another good one that I found is you tube "Van's RV fuel tank construction tips" I do have some Pro Seal experience.  Thirty years ago I built an RV-v 4 with two wing tanks to seal, but I certainly need to refresh my memory.
I bought some brass tubes 9mm od .5mm ( I think) wall thickness to make a combination tank vent and air pressure tank tube. This requires a 90* bend.  Guess what; these brass tubes are too hard to take this bend.  I tried filling the tube with sand but the tube still collapsed  and kinked. Fortunately I had a piece of 3/8" soft Cu tube. This took the 90* bend and 37* flare. If there are soft brass tubes I'd like to know of them.  Or if there is a technique to make the 90*. So be aware of this and if you know of a solution let me know.