Scott Gettings wrote:

This is my first contribution, from Scott Gettings, building a Glass Goose.
Comments below the included text.

                                 big snip

Bill, 2 tanks are in each wing. Each wing is to be connected to the
Andair fuel selector with return. The left wing tanks will NOT be 'T'd
to the right wing tanks.

Attached is a sketch.

Rich

Now I understand. TWO tanks in each wing. This is dangerous Rich.
If one tank in one wing has its line uncovered you risk not
feeding from that wing at all.

The outer tank should feed to the inner tank and then only
feed from the inner tank to the selector valve. Usually this is done
with a large diameter pipe between the two and a one way flapper valve that
prevents fuel from flowing from the inner tank back out to the outer tank.
Also the outer tank should be vented. Return fuel can go to both
OUTER tanks in each wing.

When you are low on fuel don't slip the airplane as you might
slip with the selected tanks down. I usually keep my fuel selector
on both and if I have any fuel in the upper wing the engine keeps
running. Naturally! If you have to think about which way you are slipping
and which wing is selected there is of course  more chance for error.

High wing Cessna's have far fewer tank selection based accidents
than a low wing system like you describe. Probably because
of the both position on the selector valve.

What would be even better is two small tanks in both inner wing
tanks with one way valves so if you slip you will have enough fuel
to keep the engine running for a few minutes.

Paul Lamar

Rich,

I have to agree with Paul.  Your system will almost certainly
result in fuel interruption.  Your two wing tanks T'd together
will act exactly like a left and right tank T'd together, i.e. it
will empty one and leave the other with fuel in it.

One possibility is to drain the outboard tank into the inboard,
or have a four position selector and run off of each in turn.

Simplest is to have all four tanks drain into a VENTED sump
and pump from the sump.  Each tank should have a separate
vent, not co-located (in case of FOD, it can't destroy all
four vents).  This is simple and reliable.  Run your return
to the sump, but watch for sump fuel overheating with
exceptionally long ground ops.  Please be careful.

My C182 does some very weird stuff, like empty the left
tank to about 1/8 while the right has 3/4+ in it (according to
the fuel guages).  At 1/8th, the left stops getting lower until
the right goes down to about 1/4, where they sort of get
back in synch.  This is from a VERY simple gravity system.
I believe the primary problem is the single vent used on
old C182s.  Late models have dual vents, I assume they
do better, but don't know.

Low wing systems (pumped) and esp many-tank low wing
systems are even more treacherous.  I repeat - fuel systems
do *not* behave like you expect them to.

Bill
Long EZ builder & pilot
mechanical engineer

These are interesting comments, as I had a '69 182M with the single vents.  We
always flew it on "both", and almost always had  the same fuel burn from both
tanks.  Perhaps a partially-plugged vent line, selector valve, or finger strainer
was the culprit?

After meeting with Paul and Tracy and reviewing their information, I'm strongly
considering using a rotary, as the Goose really needs 180 hp and needs to stay in
(preferably under) the 300 lb range for engine weight.  The Goose has interesting
fuel tank concerns all by itself:

The original design had 44 gal in two upper wing tanks which were originally
connected across the centerline, but later separated due to fuel displacement when
sitting at angles on a beach.  The lower wings had about 23 gallons.  Later designs
decreased the upper wing fuel from BL 120 to BL65 and increased the lower wing tank
size to 35 gal, for a total of about 75 gal.   More centrally located fuel tanks
have an advantage during water operations.

A few builders have added a header tank low in the fuselage (cockpit area) for
fuel-injected installations.  I'm considering just returning to the original upper
wing 44 gal and omitting the lower wing tanks, since a low wing tank in a flying
boat gives you all kinds of sumping problems  (got to drain inside the cockpit),
lots of additional valves and plumbing, and the lower tank just adds endurance that
is far beyond mine.

I was hoping to have a simple, high-wing, (primarily) gravity-fed system with
R/L/both/Off fuel selection.  It looks like I may have to make arrangement for a
header tank or valving with returns to the selected tank if I go with fuel
injection.  Having a complex valve with returns to the selected tank is much more
complicated in the Goose because of the location of the cockpit (in front), and the
high wing tanks and pusher engine.  Rats.

Are the majority of you guys using fuel injection in the 13B engines instead of
carbs?   Any experience regarding the relative benefits of injection vs. carbs (not
just carb ice, obviously) or header vs. returning-fuel valves?

I've enjoyed the wealth of information on this site so far!

Scott Gettings
Glass Goose
Melbourne, FL

Yes I think the majority are going with fuel injection.
For a Glass Goose with all that room behind the seats the
sump tank high up under the engine fed from the upper wings
only looks ideal. Real simple and straight forward.
No fuel selector needed. One water drain in the sump tank.
High pressure fuel pump in the tank.
A lot of automotive fuel injection pumps are attached to a 
panel that unbolts from the the top of the automotive fuel tank.
You could use this entire assemble.
All the fuel line, fuel return line and vent fittings 
are right there. (Fuel return to the sump tank.)
Plenty of room to make it about two gallons.
High percentage of usable fuel.
Two vents one in each wing tank. 
Real simple. 

Better than a Cessna.

Paul Lamar

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