FUEL TANK

[Murray Randall]

I have stored on my computer from two sources that tanks weighed 3.5 lb. I didn't record the sources but I bet one is Steve K. He's got good records.  My approx. calcs say 583 sq in, the divin at 3#/cubic ft comes to .25 lb, the 811 cloth at 9 oz/yd comes to 1.5 lb.  So 1.75 lbs before resin fittings.  Sounds doable at 3.5 lb. Is in the same ball park as alum, but not lighter.

[Bob S.]

I BUILT a Cledgecell/Glass tank but it leaked so bad I went with a plastic one.... I'll get it down and give it a weigh later this week....

[Murray Randall]

Where can you buy a fuel filler neck and cap assy to inbed into a glass tank.  

[Bob S.]

As per the plans by Leonard, he uses a piece of 1-1/4" Drain pipe with a threaded homemade "cap"....

[Steve]

Where can you buy a fuel filler neck and cap assy to inbed into a glass tank.  

http://www.fueltankparts.com/fuel-tank-parts-accessories.html?gclid=Cj0KEQiAiO-kBRCNxtaJp4-En6sBEiQAnkvW30dcGAjhTh2AkX6hPyBUreDKGJnju-vZEiqrvLoD_6QaArut8P8HAQ

http://www.fueltankparts.com/aluminum-bolt-in-threaded-cap-assembly.html

[Sam Buchanan]

Where can you buy a fuel filler neck and cap assy to inbed into a glass tank.  

I used a PVC adapter and cap from Lowes. The adapter was epoxied to an aluminum flange.

Look at the last three photos on this page:

http://eaglexl-58.com/tank.htm

[Sam Buchanan]

Where can you buy a fuel filler neck and cap assy to inbed into a glass tank.  

I used a PVC adapter and cap from Lowes. The adapter was epoxied to an aluminum flange.

Look at the last three photos on this page:

http://eaglexl-58.com/tank.htm

[docmatt]

Has anyone built a steel tank?  I have been successful with welding up motorcycle tanks.  Rust does not seem to be a problem if it is kept full, or coated on the inside.  I would think .024 would be strong enough.  Weight may be a bit more than AL or fiberglass, which for me, is the biggest drawback.  I am being obsessive about weight.

[scottiniowa]

Has anyone built a steel tank?  I have been successful with welding up motorcycle tanks.  Rust does not seem to be a problem if it is kept full, or coated on the inside.  I would think .024 would be strong enough.  Weight may be a bit more than AL or fiberglass, which for me, is the biggest drawback.  I am being obsessive about weight.

  Doc,
   a few observations:   With steel, as you say, weight will be your number 1-worry, but this is easily calculated by the provided weights of sq ft of material. So you will know before you start.  
2nd worry- always wondering if you get to hear the silence of NO fan, when flying due to foreign material going down the line. Certainly should be able to screen it with fuel filter, but…. always the worry.

But anyone with the ability to build with steel has the capability to do the same with alum. (and get a clean-light weight tank)   One simple but extremely effective way for fuel tank building the alum. way, is to use the TIN MAN’s methods (Kent White) google him gas alum welding- Very simple to learn, and extremely strong when your done.  Of course you got T I G as an option, but that is a whole different can of worms.

Best of success.  I know I didn’t give any clear answers but maybe some food for thought.

Scott

[docmatt]

Thanks for all of your thoughtful answers Scott,
I do not have TIG, but I could sure use an excuse to get it;).  I actually spent the better part of three days at Oshkosh one year at the Tin Man's booth, learning everything I could from him.  I got some of his AL flux and 1100 welding wire.  I was never able to make anything but a barely acceptable weld when I got home.  Short seams pretty good, but anything longer would end up with a hole or blob.  On the other hand, when I weld thin steel, it looks like a machine did it and it holds pressure with no problem.  I wonder how thin one could safely go with steel on a fuel tank?  You are right about the flakes left from welding inside the tank though.  A riveted and sealed AL tank may be the way for me to go.  Maybe I'll buy some sealer and try making a reserve tank for a motorcycle and see how it works out.

[Murray Randall]

I TIG welded one aviation tank and the most beautiful of welds would show a blue stain when I put in some 100 LL. Very discouraging!   TIG welding up a neighbors heavy wall farm irrigation pipes is a snap.  .020 alum is something else.   So this time its fiber glass and vinyl ester resin.   And man that is tedious.  Aviation fuel tanks are a bitch!!!    Murray

[Dan_]

 .020 alum is something else.     Aviation fuel tanks are a bitch!!!    Murray

Try .050 3003 or 5052 on your next tig welded aluminum tank...

[scottiniowa]

.020 alum is something else.     Aviation fuel tanks are a bitch!!!    Murray

Try .050 3003 or 5052 on your next tig welded aluminum tank...

Dan is spot on, that would be the standard recommendation for fuel tank building…  .020 alum NOT so… And though it has not been said,  there are somethings you just don’t want to try with certainly alum. types.  and .020 tanks would be one of them of any type.

Bungs and fill holes are all readily available from race supply houses,  side fittings for sight glass for a no-weld way is available from Rans Aircraft. 

Best of success.

[Tom H]

I've built several tanks for LEU Treehugger and DE Stubby.

The first LEU tank I tried to make was made by shaping a stack of styrofoam insulation boards, sealing w/ plastic film and tape, and covering with fiberglass and vinylester resin.  Unfortunately, the resin vapors seeped through the plastic and started melting the core.

Next I used urethane foam as a core, spread a thin film of RTV to be a release agent, then covered w/ FG and VE.  Cut a hole in the top and removed the foam.  It turned out fine, and we used it for a while, but then found gel in our carbs.  We think it was from the VE resin.  VE is supposed to be good for auto fuel, but maybe ours was out-of-date or the RTV screwed it up.  This tank weighed 5 lb 1.6 oz.

It was replaced with an alum tank that I made from 0.040 3003 sheet, tig welded.  I used 0.040 because I made some samples with 0.025 alum and found I had too many "errors".  3003 was used because it bends well, does not tend to crack and is often used in tank construction.  I did weight it, but can't find the numbers.  I do remember being surprised that it weighed nearly the same as the FG/VE tank. 

I made two other tanks for the DE.  I've attached two pics, one showing the internals, one showing it in the wing.  All the alum tanks were tested by pressurizing with 1.5 psig air, blocking off the air supply, checking w/ soap solution, and monitoring the held pressure on a pressure gauge.  After several repairs of pin holes, they eventually held pressure for over 20 hours.  No leaks in the airplane, so far.