FG gas tanks.

On Apr 5, 10:55 pm, "Roger (K8RI)" wrote:

The Glasair manuals have an excellent series of drawings with detailed
instructions for the tanks, fuel lines, and the small tank with the
"flop tube" behind the firewall and they do use Vinylester Resin..

I have a fiberglass tank in my Jodel. It's had avgas in it for
the last 13 years. It's made of glass cloth and polyester resin. And
it's heavy.
If I did it again I'd rivet up a light aluminum tank and Proseal
it.

The Jodel's tank was first formed from 1/4" "hardware cloth."
This isn't cloth at all; it's a coarse but light steel wire screen,
galvanized, with the wires 1/4" apart. It's used as screening over
attic vents and the like to keep birds and bats out. Cheap and
available at building suppliers. The walls of the tank are cut from
the screen in the shape required, with the wires sticking out all
around, and these are wired together using the bits sticking out and
maybe a little more wire where needed. The fiberglass cloth is laid
over this male mold and the resin brushed into it. Two layers of glass
should be plenty strong enough. I used more; that's one reason it's
heavy.The screen adds considerable strength on its own and lots of
cloth shouldn't be necessary. If you used fiberglass mat it would get
really heavy due to the amount of resin it would soak up. And
expensive, 'cause resin isn't cheap.
A filler neck and outlet fittings are welded to suitable bits of
thin steel sheet. The sheet is thoroughly cleaned after welding (or
brazing), scuffed up real well, maybe a few holes poked into the
edges, and these are glassed on where you want them.
I checked mine twice for leaks. I first stretched a balloon over
the filler neck and blew air into the outlet and closed that off. The
ballon went limp, so I had a leak somewhere. Soapy water found that.
Glassed it up. The balloon held after that so I next filled the thing
full of water and left it overnight. I wanted the weight to see if
anything would open up under the stress. Looked for a damp floor next
morning. Nothing. Cleaned it and dried it and stuck it in the
airplane. I wasn't afraid of the gas eating it because I'd had glass
boat tanks for years. Those were in a small inboard in which I had a
Chevy V8. They were plywood boxes, open at the top, with wood doubler
flanges glued around the top edges. Glassed inside the boxes and over
the top flange and while they were still wet the top was glassed too
and screwed on. Never, ever leaked a drop. Awful heavy.

Dan