[rebel-builders] Re: [rebel-builders] clear fuel line
Posted: Sun Feb 19, 2012 11:35 pm
One thing you lose when low on fuel.. having a tee'd in sight gauge.... is
the ability of the line to carburetor to act as a syphon. Sitting
statically.... when I was refurbishing FOKM with a tee'd in sight gauge...
it needed 10 gallons of fuel in the tank before I could even get fuel to
flow out at the carb fitting, otherwise it would draw the easiest thing and
that was air. Removing that air "induction" significantly improved fuel flow
and allowed it to empty the tank to fumes.
While the intent is to run as gravity feed in a high wing for most of
us..... I've seen a few Rebels/Elites come thru the shop where the Lycoming
engine the builder bought had a pump... so they plumbed it in as well as a
back up electric (instead of just tossing the pump). Absolutely no need for
the pump.. but it's another item that will suck that air down into the
lines. On the other hand we have guys running injected Continentals and fuel
pump equipped auto conversions, Rotax, Rotech and similar style engines. If
they are drawing off a dual port tank or tee'd sight gauge I sure hope they
have a vented header tank downstream.
Regards,
Wayne
----- Original Message -----
From: "ray" <raybot@comcast.net>
To: <rebel-builders@dcsol.com>
Sent: Friday, December 02, 2011 3:25 PM
Subject: Re: [rebel-builders] Re: [rebel-builders] clear fuel line
[quote]I have a question about this air flowing in to the fuel lines and I have
heard this mentioned before.On a gravity feed system if you have a leak or
a
loose fitting doesn,t the fuel come out? The fuel constantly seeks the
level
state so that even if one tank unports the air can only go down the line
to
the fuel level in the line,not any lower and when the plane returns to
normal flight or undoes the unporting the fuel flows back up the line from
the other tank. What I,m trying to say is if you unscrew a fitting
anywhere
in a gravity system either fuel flows out or nothing happens because the
fuel in a properly vented tank is always in equlibrium. The only way air
could 'leak' in is if a fuel pump was applying suction to a system. I
don,t
see the presure or vacumn that has the fuel moving,I only see gravity and
or
centrifigul forces acting on the fuel,or am I all wet here?I need to
understand this as I have a rebel with a gravity system and have my own
concerns about the system as is.
----- Original Message -----
From: "Eduardo Gutierrez Sosa" <lopeco.eduardo@gmail.com>
To: <rebel-builders@dcsol.com>
Sent: Friday, December 02, 2011 12:01 PM
Subject: Re: [rebel-builders] Re: [rebel-builders] clear fuel line
[quote]Hi Wayne: That's another good point that the lower sight gauge fitting be
placed sepparately to the fuel feed line, so no air flows in. I will
install
a header tank with air relief line to the top of the wing's tank (exactly
don't know how just yet). This header tank will hold approximately 5
gallons
of fuel and will be installed under the pilot's seat, below the
floorboard.
This installation is mandatory for the turbo prop engine.
I appreciate the photo you sent, it's how I will make mine too, and yes,
the
wing is upside down.
Regards, Eduardo
El 02/12/11 13:00, "Wayne G. O'Shea" <oifa@irishfield.on.ca> escribi
the ability of the line to carburetor to act as a syphon. Sitting
statically.... when I was refurbishing FOKM with a tee'd in sight gauge...
it needed 10 gallons of fuel in the tank before I could even get fuel to
flow out at the carb fitting, otherwise it would draw the easiest thing and
that was air. Removing that air "induction" significantly improved fuel flow
and allowed it to empty the tank to fumes.
While the intent is to run as gravity feed in a high wing for most of
us..... I've seen a few Rebels/Elites come thru the shop where the Lycoming
engine the builder bought had a pump... so they plumbed it in as well as a
back up electric (instead of just tossing the pump). Absolutely no need for
the pump.. but it's another item that will suck that air down into the
lines. On the other hand we have guys running injected Continentals and fuel
pump equipped auto conversions, Rotax, Rotech and similar style engines. If
they are drawing off a dual port tank or tee'd sight gauge I sure hope they
have a vented header tank downstream.
Regards,
Wayne
----- Original Message -----
From: "ray" <raybot@comcast.net>
To: <rebel-builders@dcsol.com>
Sent: Friday, December 02, 2011 3:25 PM
Subject: Re: [rebel-builders] Re: [rebel-builders] clear fuel line
[quote]I have a question about this air flowing in to the fuel lines and I have
heard this mentioned before.On a gravity feed system if you have a leak or
a
loose fitting doesn,t the fuel come out? The fuel constantly seeks the
level
state so that even if one tank unports the air can only go down the line
to
the fuel level in the line,not any lower and when the plane returns to
normal flight or undoes the unporting the fuel flows back up the line from
the other tank. What I,m trying to say is if you unscrew a fitting
anywhere
in a gravity system either fuel flows out or nothing happens because the
fuel in a properly vented tank is always in equlibrium. The only way air
could 'leak' in is if a fuel pump was applying suction to a system. I
don,t
see the presure or vacumn that has the fuel moving,I only see gravity and
or
centrifigul forces acting on the fuel,or am I all wet here?I need to
understand this as I have a rebel with a gravity system and have my own
concerns about the system as is.
----- Original Message -----
From: "Eduardo Gutierrez Sosa" <lopeco.eduardo@gmail.com>
To: <rebel-builders@dcsol.com>
Sent: Friday, December 02, 2011 12:01 PM
Subject: Re: [rebel-builders] Re: [rebel-builders] clear fuel line
[quote]Hi Wayne: That's another good point that the lower sight gauge fitting be
placed sepparately to the fuel feed line, so no air flows in. I will
install
a header tank with air relief line to the top of the wing's tank (exactly
don't know how just yet). This header tank will hold approximately 5
gallons
of fuel and will be installed under the pilot's seat, below the
floorboard.
This installation is mandatory for the turbo prop engine.
I appreciate the photo you sent, it's how I will make mine too, and yes,
the
wing is upside down.
Regards, Eduardo
El 02/12/11 13:00, "Wayne G. O'Shea" <oifa@irishfield.on.ca> escribi