having the rear outlets. It seems that this is a popular misconception out
there with some homebuilders, not just Murphy planes, where they think 2
outlets are safer.
I know of another plane where some builders had installed a front outlet as
well, and to make it worse, the engine also had a fuel pump. Well, it didn't
take long for engine outs to occur when tanks were low, and during an
initial steep climb. Needless to say, this was a hard lesson for some.
With the Rebel, you need to also be aware that if you have the tank shut off
valves up top at the rear of the tanks, instead of the bottom, you can
easily get an air block in the lines when switching tanks, if you run one
tank dry in the air and don't use the correct tank switching procedure. More
specifically, if you are running on one tank, let it go dry, close it, then
open the other tank, your engine will quit, guaranteed, every time. I proved
this myself, on the ground, and it is very repeatable.
The correct procedure is to open the other full side first, and when the
engine is confirmed to keep running OK, then the empty tank can be closed.
What happens with the incorrect sequence, is that air is sitting in your
lines below the valves, and if you close your empty one, it can not escape
when the full one is opened.
This is a very important point to understand if you don't want any rude
surprises some day when switching tanks.
Walter
-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com] On Behalf Of
Wayne G. O'Shea
Sent: Friday, February 02, 2007 9:25 AM
To: rebel-builders@dcsol.com
Subject: Re: [rebel-builders] Fuel Tank
You would have to stuff the nose VERY hard to unport the fuel fitting even
low on fuel. Double porting also negates the syphon effect the fuel line
would have with just the rear port, as when you get low on fuel as it will
draw air from the front port easier than fuel from the back, especially if
you are running a fuel pump. Even the old style of fuel gauge sight
fitting
tee'd into the main outlet stopped the syphon ability of the tank.
Starting
with an empty tank it would take adding 10 gallons of fuel to the tank....
to get fuel to flow to the carb on FOKM before I changed the site gauge
set
up to a seperate isolated fitting. After moving it fuel flow became almost
instant with the first few gallons added to the tank.
Wayne
----- Original Message -----
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