Rebel Fuel Management

[Walter Klatt]

Thanks, Angus, that's what I was looking for. And what is the
lowest fuel level of your left tank that you have had prior to
switch over?

Walter

-----Original Message-----
From: mike.davis@dcsol.com
[mailto:mike.davis@dcsol.com]On Behalf Of
Angus McKenzie
Sent: Tuesday, December 14, 2004 4:24 PM
To: rebel-builders@dcsol.com
Subject: Re: RE: Rebel Fuel Management


Hi Walter
I too run my first tank dry.I always run my right tank
first then at the
first engine sputter reach over my head and open the
left valve then reach
across and shut off the other side. Usually get 2.5
hrs per side,depending
on how rough the air is.............Angus


----- Original Message -----
From: "WALTER KLATT" <Walter.Klatt@shaw.ca>
To: <rebel-builders@dcsol.com>
Sent: Tuesday, December 14, 2004 11:42 AM
Subject: Re: RE: Rebel Fuel Management

Drew, can you give me a couple more specifics about

your fuel system. Do
you have the standard MAM shut-off valves up top at
the tank outlets? Where
are the lines tee'd together?

And when you run a tank dry, exactly what order do

you open and close the
valves? Do you first close the empty tank and then
open the full one? Or do
you open the full one first, and close the empty one
after the engine starts
up again?

Walter

----- Original Message -----
From: Drew Dalgleish <drewjan@cabletv.on.ca>
Date: Tuesday, December 14, 2004 7:26 am
Subject: RE: Rebel Fuel Management

At 08:41 PM 12/13/2004 -0800, you wrote:

tanks are

do not lean when

might have been lead

gascolator, so if

I also did a

gascolator after

trapped in the lines

opening the empty

how some people

any problems.

of not ever

to get them

over hostile

the primer to

Hi Walter I've run one tank dry in flight a few

times on long cross

countries when I'm getting near maximun range for the fuel
carried. I feel
better having all my remaining fuel in one tank

rather than split

between 2
just because I've also had the problem of

unporting the intake

pipe with
low fuel when cranking and banking close to the

ground. My vent is

at the
wing root on the pilots side and that tank seems

to feed a little

fasterthan the other one. so it's easier to manage

just one tank

at a time.
Drew

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[Phil Stubley]

THE PROBLEM IS AIR IN THE LINE AT THE TANK OUTLET

Pardon me for screaming but I see the problem surfacing again and again.

First, what happens, then how I know, thirdly, why not shut off one tank,
and lastly, what I did to my setup

What happens:
A bubble of air gets in the tank outlet or the line somewhere, due usually
to something you have done, such as DRAINING ONE TANK DRY. Then shutting
off one tank makes it impossible for this bubble to get back into the tank.
There is no head to move it.

But a lot of fuel will flow past this bubble, enough to start the engine and
do a runup to 50-60%, but not enough for full power. Result, all checks are
fine until you get about 50 ft in the air, and the carb runs dry. Been
there, done that... Sure gets the heart rate up.

How I know, the tests, and what I found out:
Because of the problems when the rebels were first using the big engines
(problem doesn't show with small engines because full power can be handled
right past a bubble.) I got 'clever' and designed a system that would
swallow a bubble before it did anything to the engine. An oversized
reservoir on the top of the gascolator, vented back to the tank crossover
vent line.

Until one day I decided to use avgas in one tank and mogas in the other, and
tried to takeoff on one tank, after I had drained a tank to ensure I didn't
have a mixture in the tank under test. That's when I scared myself.

So I duplicated the phenomenon on the ground, getting a bubble in one line
by putting one wheel in the ditch for a slope. Could do runup power, but 40
secs of full power and it just fell to about 10% power for a few secs and
then picked up full power.

To the lab: actually a bunch of plastic tubing in the back yard, with lots
of little needle valves and some water, a measuring cup and a stop watch. I
could watch a bubble sit in the line at a horizontal bend ( like the
situation at the tank outlet) and try to move down as the flow increased. I
could make a bubble hang about 6in down the tube without going any farther.
If the flow reduced it moved back up, but never all of it into the reservoir
(tank). At a high flow it did break free and travel down the tubing. I
measured the flows using water, not vouching for the accuracy but the flow
at breakaway was equivalent to more than 5 gpm, which I judged to be above
the runup requirements of 1800 rpm, and certainly less than full power.

Why both tanks always on:
I run ALWAYS with both tanks on. Any bubble could be driven back into the
tank by a flow from the other tank, and even if there was a bubble the
combined flow from both tanks should be enough for full throttle. What
happens when a tank runs dry and you have both on? The flow from that side
will stop when the level drops down the tubing, and all the flow will come
from the other tank. A sideslip will cause some variations in this level,
but it will right itself before you could be far enough off level (gravity
wise) to add more than a foot to the situation. And you have about 3 feet
head to play with. (This argument may not apply to a pumped system)

If you have only one tank on, then a sideslip CAN cause a bubble to enter
the line by uncovering the port while you have some flow. (This is usually
not a problem because the flow during a sideslip is almost nil).
Conclusion: no danger from running on two tanks even if one is empty.
Danger from running with only one tank on.

Finally, what I have done:
Because a bubble will flow up the line until it reaches a horizontal
section, (especially one with lots of steps like the outlet through the
strainer, reducer, elbow, tube/hose transition, valve et al), I put a bubble
extractor at that location. It is basically like the sloping level gauge
but with a tee that has a cavity in it, and a vent line back to the top of
the tank instead of a clear sight tube. I also put the shutoff after this
tee to allow full isolation of the tank from any other lines. I even
removed the crossover vent, deciding it was more of a hazard in an upside
down situation.
So now I think I have a belt and braces setup.

So that's my story about fuel flow problems.
And bobp, keep both valves open on your setup. It is just asking for a
bubble to get stuck in that looping line!!
And Walter, the air-in-the-line theory fits your experience exactly.

.>>> One is that I

still may have had some air in my lines after bringing the

second

tank online after fuelling. My run-ups are only at 1800 rpm
because of my amphib brakes. The other is that I may have got
some carb ice after sitting at idle so long waiting for my turn
to take off. OAT on the ground at that time was about 5 C (40F).
Or maybe my plugs fouled up a bit with lead with the long idle.

Any thoughts? I don't like mysteries of this kind.

Me too!!!

Phil.





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[Drew Dalgleish]

At 08:42 AM 12/14/2004 -0800, you wrote:

Drew, can you give me a couple more specifics about your fuel system. Do

you have the standard MAM shut-off valves up top at the tank outlets? Where
are the lines tee'd together?

And when you run a tank dry, exactly what order do you open and close the

valves? Do you first close the empty tank and then open the full one? Or do
you open the full one first, and close the empty one after the engine
starts up again?

Walter

I have my shut offs in the standard spot. I used larger valves than MAM
supplied. What is your kit # on the early kits there was an AD to drill out
the valves to 3/8". My lines tee together at the firewall right behind the
gascolator. When I run out of gas I open the full tank and immediatly close
the empty tank. The engine restarts quite quickly with little altitude loss
but it's not something I would do if flying around at 500'agl.
Drew





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[Drew Dalgleish]

At 04:55 PM 12/14/2004 -0800, you wrote:

Thanks, Angus, that's what I was looking for. And what is the
lowest fuel level of your left tank that you have had prior to
switch over?

Walter

I empty my tank completly by flying with one wing slightly low
Drew





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[Angus McKenzie]

Walter.........In smooth air you can just barely see fuel in the sight-tube
when it is time to switch.In rough air much sooner.I should have the litres
required to fill from empty written somewhere and will check for it.I should
mention that when you open the full side valve the fuel level in the sight
tube of
the empty tank jumps up 1/2"-1" and maintains that level even with the empty
tank valve closed.We have had issues when running on both tanks when it has
appeared that you have more fuel available than there actually is.This
happened from running on one tank to empty and establishing a known
reference then expecting to view the same level in the tube when running on
both tanks.What we had expected to be a safe level in the sight-tube when
running on both tanks we learned was different from the single tank
indication.Does this make any sense?
As you know there is no substitute for safe fuel management with a
functioning time-piece and this is what I rely on.I have the reference
marks on the tubes and refer to them for verifying what my watch tells me
........Angus


----- Original Message -----
From: "Walter Klatt" <Walter.Klatt@shaw.ca>
To: <rebel-builders@dcsol.com>
Sent: Tuesday, December 14, 2004 7:55 PM
Subject: RE: RE: Rebel Fuel Management

Thanks, Angus, that's what I was looking for. And what is the
lowest fuel level of your left tank that you have had prior to
switch over?

Walter

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[Walter Klatt]

Thanks Phil, that was very interesting, and it supports that my
engine faltering on take-off was not just coincidental with my
draining one tank and refuelling just prior.

And from what you're saying it also explains why keeping the
empty tank open helps establish the flow from the full one, too.
Again, that explains my experience on the ground.

So, based on your recommendation, keeping both valves open even
if one tank goes dry first is the way to do it. Have you ever run
it that low, and what happened?

Walter

-----Original Message-----
From: mike.davis@dcsol.com
[mailto:mike.davis@dcsol.com]On Behalf Of
Phil Stubley
Sent: Tuesday, December 14, 2004 7:53 PM
To: rebel-builders@dcsol.com
Subject: Re: Rebel Fuel Management


THE PROBLEM IS AIR IN THE LINE AT THE TANK OUTLET

Pardon me for screaming but I see the problem
surfacing again and again.

First, what happens, then how I know, thirdly, why not
shut off one tank,
and lastly, what I did to my setup

What happens:
A bubble of air gets in the tank outlet or the line
somewhere, due usually
to something you have done, such as DRAINING ONE TANK
DRY. Then shutting
off one tank makes it impossible for this bubble to
get back into the tank.
There is no head to move it.

But a lot of fuel will flow past this bubble, enough
to start the engine and
do a runup to 50-60%, but not enough for full power.
Result, all checks are
fine until you get about 50 ft in the air, and the
carb runs dry. Been
there, done that... Sure gets the heart rate up.

How I know, the tests, and what I found out:
Because of the problems when the rebels were first
using the big engines
(problem doesn't show with small engines because full
power can be handled
right past a bubble.) I got 'clever' and designed a
system that would
swallow a bubble before it did anything to the engine.
An oversized
reservoir on the top of the gascolator, vented back to
the tank crossover
vent line.

Until one day I decided to use avgas in one tank and
mogas in the other, and
tried to takeoff on one tank, after I had drained a
tank to ensure I didn't
have a mixture in the tank under test. That's when I
scared myself.

So I duplicated the phenomenon on the ground, getting
a bubble in one line
by putting one wheel in the ditch for a slope. Could
do runup power, but 40
secs of full power and it just fell to about 10% power
for a few secs and
then picked up full power.

To the lab: actually a bunch of plastic tubing in the
back yard, with lots
of little needle valves and some water, a measuring
cup and a stop watch. I
could watch a bubble sit in the line at a horizontal
bend ( like the
situation at the tank outlet) and try to move down as
the flow increased. I
could make a bubble hang about 6in down the tube
without going any farther.
If the flow reduced it moved back up, but never all of
it into the reservoir
(tank). At a high flow it did break free and travel
down the tubing. I
measured the flows using water, not vouching for the
accuracy but the flow
at breakaway was equivalent to more than 5 gpm, which
I judged to be above
the runup requirements of 1800 rpm, and certainly less
than full power.

Why both tanks always on:
I run ALWAYS with both tanks on. Any bubble could be
driven back into the
tank by a flow from the other tank, and even if there
was a bubble the
combined flow from both tanks should be enough for
full throttle. What
happens when a tank runs dry and you have both on?
The flow from that side
will stop when the level drops down the tubing, and
all the flow will come
from the other tank. A sideslip will cause some
variations in this level,
but it will right itself before you could be far
enough off level (gravity
wise) to add more than a foot to the situation. And
you have about 3 feet
head to play with. (This argument may not apply to a
pumped system)

If you have only one tank on, then a sideslip CAN
cause a bubble to enter
the line by uncovering the port while you have some
flow. (This is usually
not a problem because the flow during a sideslip is
almost nil).
Conclusion: no danger from running on two tanks even
if one is empty.
Danger from running with only one tank on.

Finally, what I have done:
Because a bubble will flow up the line until it
reaches a horizontal
section, (especially one with lots of steps like the
outlet through the
strainer, reducer, elbow, tube/hose transition, valve
et al), I put a bubble
extractor at that location. It is basically like the
sloping level gauge
but with a tee that has a cavity in it, and a vent
line back to the top of
the tank instead of a clear sight tube. I also put
the shutoff after this
tee to allow full isolation of the tank from any other
lines. I even
removed the crossover vent, deciding it was more of a
hazard in an upside
down situation.
So now I think I have a belt and braces setup.

So that's my story about fuel flow problems.
And bobp, keep both valves open on your setup. It is
just asking for a
bubble to get stuck in that looping line!!
And Walter, the air-in-the-line theory fits your
experience exactly.

.>>> One is that I

bringing the

second

at 1800 rpm

may have got

waiting for my turn

about 5 C (40F).

the long idle.

Me too!!!

Phil.





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[WALTER KLATT]

Sorry, my question is what is the lowest fuel level of the tank that you are switching to, not the one you are draining? For example, 5 g is still legal by day, and have you ever done it that low? I would suspect not, but how low. The danger I see still is getting air bubbles into the line when it is low due to turbulence, etc. and fuel flow stopping as described by Phil. That's why I am asking.

Walter

----- Original Message -----
From: Drew Dalgleish <drewjan@cabletv.on.ca>
Date: Wednesday, December 15, 2004 6:27 am
Subject: RE: RE: Rebel Fuel Management

At 04:55 PM 12/14/2004 -0800, you wrote:

Thanks, Angus, that's what I was looking for. And what is the
lowest fuel level of your left tank that you have had prior to
switch over?

Walter

I empty my tank completly by flying with one wing slightly low
Drew





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[WALTER KLATT]

While I have an older kit 107, I upgraded to the new valves, and sounds like my set-up is identical to yours.

From what I gathered in these messages, it sounds like best practice might be to not close the empty tank until the engine resumes on the new one. Or as Phil suggests, not close the empty one at all. And opening the primer in flight for a bit should also clear any air out of the gascolator. Then a short full power climb should confirm that all is well.

Walter

----- Original Message -----
From: Drew Dalgleish <drewjan@cabletv.on.ca>
Date: Tuesday, December 14, 2004 3:50 pm
Subject: Re: RE: Rebel Fuel Management

At 08:42 AM 12/14/2004 -0800, you wrote:

Drew, can you give me a couple more specifics about your fuel

system. Do
you have the standard MAM shut-off valves up top at the tank
outlets? Where
are the lines tee'd together?

And when you run a tank dry, exactly what order do you open and

close the
valves? Do you first close the empty tank and then open the full
one? Or do
you open the full one first, and close the empty one after the engine
starts up again?

Walter

I have my shut offs in the standard spot. I used larger valves
than MAM
supplied. What is your kit # on the early kits there was an AD to
drill out
the valves to 3/8". My lines tee together at the firewall right
behind the
gascolator. When I run out of gas I open the full tank and
immediatly close
the empty tank. The engine restarts quite quickly with little
altitude loss
but it's not something I would do if flying around at 500'agl.
Drew





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[Ken]

Hi Angus
It sounds like you still have the bottom of the sight gauge connected to
the fuel tank outlet. I wouldn't expect your gauge observations to apply
to the installations that have followed the newer recommendation to
isolate the sight gauge with a dedicated lower connection into the tank.
Ken

Angus McKenzie wrote:

Walter.........In smooth air you can just barely see fuel in the sight-tube
when it is time to switch.In rough air much sooner.I should have the litres
required to fill from empty written somewhere and will check for it.I should
mention that when you open the full side valve the fuel level in the sight
tube of
the empty tank jumps up 1/2"-1" and maintains that level even with the empty
tank valve closed.We have had issues when running on both tanks when it has
appeared that you have more fuel available than there actually is.This
happened from running on one tank to empty and establishing a known
reference then expecting to view the same level in the tube when running on
both tanks.What we had expected to be a safe level in the sight-tube when
running on both tanks we learned was different from the single tank
indication.Does this make any sense?
As you know there is no substitute for safe fuel management with a
functioning time-piece and this is what I rely on.I have the reference
marks on the tubes and refer to them for verifying what my watch tells me
........Angus

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[WALTER KLATT]

Yes, it has been quite an interesting discussion for me. We've been over some of this before on the list, but this time I think I've actually learned a few new things, that for some reason weren't getting through my thick skull before. Perhaps I might recap some of these, and anyone please correct me again, if I get it wrong. I take fuel management very seriously, and while I have never been close to running out so far, and don't intend to, but if I ever do get into an inadvertant low fuel situation, I want to be sure that I don't take any wrong actions that might risk my butt further. So here is what I have learned:

1. If you do run a tank dry, do not close the empty tank before opening the new one and before the engine has resumed power. Also, I would open the primer briefly and let the engine suck out the air from the gascolator, and give it a few pumps until I feel it squirting fuel or the engine roughens from the overly rich mixture in the cylinders. Then do a brief full power climb as a final confirmation.

2. If you do get real low on fuel, keep running on both, even right to the last drop. If one tank runs dry first, it will not mean immediate engine stoppage, as long as there is still some fuel in the other tank. Previously, I would have thought it was best to run one tank dry, and then switch to the fuller one for the final stretch. I will still switch tanks to balance them or if I have mogas or avgas that I am using up, but when both tanks are low, both valves will be open.

3. If building again, I might consider having my two fuel valves or a selector at floor level instead of only up top on the tank outlets. That way I will never have air trapped in my lines and a full 3 foot gravity head always available to get the fuel moving immediately after switching from an empty tank. I still might want the fuel shut-offs also on top, for emergency purposes, such as an accident to keep fuel out of the cabin.

These were the main points for me. If anyone disagrees, I would sure like to hear it and why. As the saying goes, it's not just what you know that will hurt you, but what you know that ain't so.

Rick and Phil have suggested some mods with header tanks and bubble removers, which can only help further. But since my engine is not fuel injected and does not require fuel pressure for the carb, I'm still OK with the current set-up.

Of course, all of this does not take the place of good fuel management using your watch and knowing your fuel flow. I also have the sight gauges not connected to the fuel outlets, and a fuel flow monitor. I really like the fuel flow monitor, as I have always found it to be totally accurate. And I know my exact fuel flow at any given time.

Thanks to all who contributed.

Walter


----- Original Message -----
From: Rick Harper <rjwh@optusnet.com.au>
Date: Wednesday, December 15, 2004 1:32 pm
Subject: Re: RE: RE: Rebel Fuel Management

G'day from OZ Walter ....

I have been following your e-mails regarding fuel management
with a
fair amount of interest as I nearly did it to myself - ( ran out
of fuel
), a few years back - when we were using an 0-235 .
( I might point out that this time that the problem was all my own
doing
....not paying enough attention to fuel management while
entertaining a
friend (a fellow Rebel builder visiting from America ) - and
encountering several unplanned alterations to our flight )

I realized very early on in the piece that the original MAM
system of
having a vertical sight tube meant that you couldn't tell what the
fuel
level was (by about 30 litres in each tank ), once the fuel level
got
down to the bottom sight glass elbow - something that I really
didn't
like ......

So I moved the bottom of the sight glass / tube to be common with
the
fuel outlet ( which is what everyone is saying you should not do )
....
BUT because the sight tube is now twice as long and diagonal - the
readings I get are very accurate - something I really do like !!!

(I filled each tank five litres at a time and marked the fuel
position
within tube on the back side of the tube - for when the plane was
on the
ground, and the front side of the tube- for when the plane was in
the
flying attitude .... so the gauge is dead accurate whether the
plane
is on the ground or in the air !)

As for the problem of the sight tube allowing air to enter the
fuel line
.... this IS only a problem when the fuel level gets very low -
and in
turbulence .... So...... one of my " to do " list items is - to
make
two small header tanks - with bubble release lines - on each fuel
line
just as they go vertically down after leaving the tank outlets

These two small header tanks ( about two litres capacity each )
will
have sight glasses on them themselves and will release any
bubbles
back to the fuel tank - through the top elbow connection of the
sight
tube

This means that you will always be able to tell when you're down
to the
last couple of litres - LITERALLY .... and that you won't get
any
bubbles in the fuel lines .. ( something I really want to avoid
with a
fuel injected engine ! )

Rick Harper
541 R


----- Original Message -----
From: WALTER KLATT
To: rebel-builders@dcsol.com
Sent: Thursday, December 16, 2004 3:52 AM
Subject: Re: RE: RE: Rebel Fuel Management


Sorry, my question is what is the lowest fuel level of the tank
that
you are switching to, not the one you are draining? For example, 5
g is
still legal by day, and have you ever done it that low? I would
suspect
not, but how low. The danger I see still is getting air bubbles
into the
line when it is low due to turbulence, etc. and fuel flow stopping
as
described by Phil. That's why I am asking.

Walter

----- Original Message -----
From: Drew Dalgleish <drewjan@cabletv.on.ca>
Date: Wednesday, December 15, 2004 6:27 am
Subject: RE: RE: Rebel Fuel Management

At 04:55 PM 12/14/2004 -0800, you wrote:

Thanks, Angus, that's what I was looking for. And what is the
lowest fuel level of your left tank that you have had prior to
switch over?

Walter

I empty my tank completly by flying with one wing slightly low
Drew





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[Rick Harper]

G'day from OZ Walter ....

I have been following your e-mails regarding fuel management with a
fair amount of interest as I nearly did it to myself - ( ran out of fuel
), a few years back - when we were using an 0-235 .
( I might point out that this time that the problem was all my own doing
....not paying enough attention to fuel management while entertaining a
friend (a fellow Rebel builder visiting from America ) - and
encountering several unplanned alterations to our flight )

I realized very early on in the piece that the original MAM system of
having a vertical sight tube meant that you couldn't tell what the fuel
level was (by about 30 litres in each tank ), once the fuel level got
down to the bottom sight glass elbow - something that I really didn't
like ......

So I moved the bottom of the sight glass / tube to be common with the
fuel outlet ( which is what everyone is saying you should not do ) ....
BUT because the sight tube is now twice as long and diagonal - the
readings I get are very accurate - something I really do like !!!

(I filled each tank five litres at a time and marked the fuel position
within tube on the back side of the tube - for when the plane was on the
ground, and the front side of the tube- for when the plane was in the
flying attitude .... so the gauge is dead accurate whether the plane
is on the ground or in the air !)

As for the problem of the sight tube allowing air to enter the fuel line
.... this IS only a problem when the fuel level gets very low - and in
turbulence .... So...... one of my " to do " list items is - to make
two small header tanks - with bubble release lines - on each fuel line
just as they go vertically down after leaving the tank outlets

These two small header tanks ( about two litres capacity each ) will
have sight glasses on them themselves and will release any bubbles
back to the fuel tank - through the top elbow connection of the sight
tube

This means that you will always be able to tell when you're down to the
last couple of litres - LITERALLY .... and that you won't get any
bubbles in the fuel lines .. ( something I really want to avoid with a
fuel injected engine ! )

Rick Harper
541 R


----- Original Message -----
From: WALTER KLATT
To: rebel-builders@dcsol.com
Sent: Thursday, December 16, 2004 3:52 AM
Subject: Re: RE: RE: Rebel Fuel Management


Sorry, my question is what is the lowest fuel level of the tank that
you are switching to, not the one you are draining? For example, 5 g is
still legal by day, and have you ever done it that low? I would suspect
not, but how low. The danger I see still is getting air bubbles into the
line when it is low due to turbulence, etc. and fuel flow stopping as
described by Phil. That's why I am asking.

Walter

----- Original Message -----
From: Drew Dalgleish <drewjan@cabletv.on.ca>
Date: Wednesday, December 15, 2004 6:27 am
Subject: RE: RE: Rebel Fuel Management

At 04:55 PM 12/14/2004 -0800, you wrote:

Thanks, Angus, that's what I was looking for. And what is the
lowest fuel level of your left tank that you have had prior to
switch over?

Walter

I empty my tank completly by flying with one wing slightly low
Drew





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[Ted I Weitz]

Walter,

thanks for bringing up the subject, great to learn from this discussion.

I didn't understand the primer stuff you wrote. Do you see the engine
sucking the air to clear the line while providing the needed fuel with the
primer?

What do you and the group think on adding an electric fuel pump down the
line. Always thought that having a pump will provide some insurance as it
can force the fuel through some bad stuff including air, dirt, sloshing
particles etc.

The other thing is my mistrust of plain gravity feeds at a very low fuel
level and some unusual attitude and high Gs

What do you think?

Ted
----- Original Message -----
From: "WALTER KLATT" <Walter.Klatt@shaw.ca>
To: <rebel-builders@dcsol.com>
Sent: Wednesday, December 15, 2004 6:38 PM
Subject: Re: RE: RE: Rebel Fuel Management

Yes, it has been quite an interesting discussion for me. We've been over

some of this before on the list, but this time I think I've actually learned
a few new things, that for some reason weren't getting through my thick
skull before. Perhaps I might recap some of these, and anyone please correct
me again, if I get it wrong. I take fuel management very seriously, and
while I have never been close to running out so far, and don't intend to,
but if I ever do get into an inadvertant low fuel situation, I want to be
sure that I don't take any wrong actions that might risk my butt further. So
here is what I have learned:

1. If you do run a tank dry, do not close the empty tank before opening

the new one and before the engine has resumed power. Also, I would open the
primer briefly and let the engine suck out the air from the gascolator, and
give it a few pumps until I feel it squirting fuel or the engine roughens
from the overly rich mixture in the cylinders. Then do a brief full power
climb as a final confirmation.

2. If you do get real low on fuel, keep running on both, even right to the

last drop. If one tank runs dry first, it will not mean immediate engine
stoppage, as long as there is still some fuel in the other tank. Previously,
I would have thought it was best to run one tank dry, and then switch to the
fuller one for the final stretch. I will still switch tanks to balance them
or if I have mogas or avgas that I am using up, but when both tanks are low,
both valves will be open.

3. If building again, I might consider having my two fuel valves or a

selector at floor level instead of only up top on the tank outlets. That way
I will never have air trapped in my lines and a full 3 foot gravity head
always available to get the fuel moving immediately after switching from an
empty tank. I still might want the fuel shut-offs also on top, for emergency
purposes, such as an accident to keep fuel out of the cabin.

These were the main points for me. If anyone disagrees, I would sure like

to hear it and why. As the saying goes, it's not just what you know that
will hurt you, but what you know that ain't so.

Rick and Phil have suggested some mods with header tanks and bubble

removers, which can only help further. But since my engine is not fuel
injected and does not require fuel pressure for the carb, I'm still OK with
the current set-up.

Of course, all of this does not take the place of good fuel management

using your watch and knowing your fuel flow. I also have the sight gauges
not connected to the fuel outlets, and a fuel flow monitor. I really like
the fuel flow monitor, as I have always found it to be totally accurate.
And I know my exact fuel flow at any given time.

Thanks to all who contributed.

Walter


----- Original Message -----
From: Rick Harper <rjwh@optusnet.com.au>
Date: Wednesday, December 15, 2004 1:32 pm
Subject: Re: RE: RE: Rebel Fuel Management

G'day from OZ Walter ....

I have been following your e-mails regarding fuel management
with a
fair amount of interest as I nearly did it to myself - ( ran out
of fuel
), a few years back - when we were using an 0-235 .
( I might point out that this time that the problem was all my own
doing
....not paying enough attention to fuel management while
entertaining a
friend (a fellow Rebel builder visiting from America ) - and
encountering several unplanned alterations to our flight )

I realized very early on in the piece that the original MAM
system of
having a vertical sight tube meant that you couldn't tell what the
fuel
level was (by about 30 litres in each tank ), once the fuel level
got
down to the bottom sight glass elbow - something that I really
didn't
like ......

So I moved the bottom of the sight glass / tube to be common with
the
fuel outlet ( which is what everyone is saying you should not do )
....
BUT because the sight tube is now twice as long and diagonal - the
readings I get are very accurate - something I really do like !!!

(I filled each tank five litres at a time and marked the fuel
position
within tube on the back side of the tube - for when the plane was
on the
ground, and the front side of the tube- for when the plane was in
the
flying attitude .... so the gauge is dead accurate whether the
plane
is on the ground or in the air !)

As for the problem of the sight tube allowing air to enter the
fuel line
.... this IS only a problem when the fuel level gets very low -
and in
turbulence .... So...... one of my " to do " list items is - to
make
two small header tanks - with bubble release lines - on each fuel
line
just as they go vertically down after leaving the tank outlets

These two small header tanks ( about two litres capacity each )
will
have sight glasses on them themselves and will release any
bubbles
back to the fuel tank - through the top elbow connection of the
sight
tube

This means that you will always be able to tell when you're down
to the
last couple of litres - LITERALLY .... and that you won't get
any
bubbles in the fuel lines .. ( something I really want to avoid
with a
fuel injected engine ! )

Rick Harper
541 R


----- Original Message -----
From: WALTER KLATT
To: rebel-builders@dcsol.com
Sent: Thursday, December 16, 2004 3:52 AM
Subject: Re: RE: RE: Rebel Fuel Management


Sorry, my question is what is the lowest fuel level of the tank
that
you are switching to, not the one you are draining? For example, 5
g is
still legal by day, and have you ever done it that low? I would
suspect
not, but how low. The danger I see still is getting air bubbles
into the
line when it is low due to turbulence, etc. and fuel flow stopping
as
described by Phil. That's why I am asking.

Walter

----- Original Message -----
From: Drew Dalgleish <drewjan@cabletv.on.ca>
Date: Wednesday, December 15, 2004 6:27 am
Subject: RE: RE: Rebel Fuel Management

At 04:55 PM 12/14/2004 -0800, you wrote: I empty my tank completly by flying with one wing slightly low
Drew





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[Wayne G. O'Shea]

I actually suggested to Walter that if he ever empties his fuel system
again..... by draining till dry thru the gascolator..that once he turns fuel
back on/fills tank/etc that to be sure he has all the air out of the system
to use the primer to draw the air off the top of the gascolator. Not sure if
it's a great idea in flight.....but then again I bet it would be better than
nothing if the engine was sputtering on the air in the line between the
gascolator and the venturi. At least if he got the air out of the gascolator
and then some fuel he could run the engine on the primer until the carb
started doing it's job again!

Cheers,
Wayne

----- Original Message -----
From: "Ted I Weitz" <me@tedweitz.com>
To: <rebel-builders@dcsol.com>
Sent: Wednesday, December 15, 2004 9:07 PM
Subject: Re: RE: RE: Rebel Fuel Management

Walter,

thanks for bringing up the subject, great to learn from this discussion.

I didn't understand the primer stuff you wrote. Do you see the engine
sucking the air to clear the line while providing the needed fuel with the
primer?

What do you and the group think on adding an electric fuel pump down the
line. Always thought that having a pump will provide some insurance as it
can force the fuel through some bad stuff including air, dirt, sloshing
particles etc.

The other thing is my mistrust of plain gravity feeds at a very low fuel
level and some unusual attitude and high Gs

What do you think?

Ted
----- Original Message -----
From: "WALTER KLATT" <Walter.Klatt@shaw.ca>
To: <rebel-builders@dcsol.com>
Sent: Wednesday, December 15, 2004 6:38 PM
Subject: Re: RE: RE: Rebel Fuel Management

Yes, it has been quite an interesting discussion for me. We've been over

some of this before on the list, but this time I think I've actually

learned

a few new things, that for some reason weren't getting through my thick
skull before. Perhaps I might recap some of these, and anyone please

correct

me again, if I get it wrong. I take fuel management very seriously, and
while I have never been close to running out so far, and don't intend to,
but if I ever do get into an inadvertant low fuel situation, I want to be
sure that I don't take any wrong actions that might risk my butt further.

So

here is what I have learned:

1. If you do run a tank dry, do not close the empty tank before opening

the new one and before the engine has resumed power. Also, I would open

the

primer briefly and let the engine suck out the air from the gascolator,

and

give it a few pumps until I feel it squirting fuel or the engine roughens
from the overly rich mixture in the cylinders. Then do a brief full power
climb as a final confirmation.

2. If you do get real low on fuel, keep running on both, even right to

the

last drop. If one tank runs dry first, it will not mean immediate engine
stoppage, as long as there is still some fuel in the other tank.

Previously,

I would have thought it was best to run one tank dry, and then switch to

the

fuller one for the final stretch. I will still switch tanks to balance

them

or if I have mogas or avgas that I am using up, but when both tanks are

low,

both valves will be open.

3. If building again, I might consider having my two fuel valves or a

selector at floor level instead of only up top on the tank outlets. That

way

I will never have air trapped in my lines and a full 3 foot gravity head
always available to get the fuel moving immediately after switching from

an

empty tank. I still might want the fuel shut-offs also on top, for

emergency

purposes, such as an accident to keep fuel out of the cabin.

These were the main points for me. If anyone disagrees, I would sure

like

to hear it and why. As the saying goes, it's not just what you know that
will hurt you, but what you know that ain't so.

Rick and Phil have suggested some mods with header tanks and bubble

removers, which can only help further. But since my engine is not fuel
injected and does not require fuel pressure for the carb, I'm still OK

with

the current set-up.

Of course, all of this does not take the place of good fuel management

using your watch and knowing your fuel flow. I also have the sight gauges
not connected to the fuel outlets, and a fuel flow monitor. I really like
the fuel flow monitor, as I have always found it to be totally accurate.
And I know my exact fuel flow at any given time.

Thanks to all who contributed.

Walter


----- Original Message -----
From: Rick Harper <rjwh@optusnet.com.au>
Date: Wednesday, December 15, 2004 1:32 pm
Subject: Re: RE: RE: Rebel Fuel Management

G'day from OZ Walter ....

I have been following your e-mails regarding fuel management
with a
fair amount of interest as I nearly did it to myself - ( ran out
of fuel
), a few years back - when we were using an 0-235 .
( I might point out that this time that the problem was all my own
doing
....not paying enough attention to fuel management while
entertaining a
friend (a fellow Rebel builder visiting from America ) - and
encountering several unplanned alterations to our flight )

I realized very early on in the piece that the original MAM
system of
having a vertical sight tube meant that you couldn't tell what the
fuel
level was (by about 30 litres in each tank ), once the fuel level
got
down to the bottom sight glass elbow - something that I really
didn't
like ......

So I moved the bottom of the sight glass / tube to be common with
the
fuel outlet ( which is what everyone is saying you should not do )
....
BUT because the sight tube is now twice as long and diagonal - the
readings I get are very accurate - something I really do like !!!

(I filled each tank five litres at a time and marked the fuel
position
within tube on the back side of the tube - for when the plane was
on the
ground, and the front side of the tube- for when the plane was in
the
flying attitude .... so the gauge is dead accurate whether the
plane
is on the ground or in the air !)

As for the problem of the sight tube allowing air to enter the
fuel line
.... this IS only a problem when the fuel level gets very low -
and in
turbulence .... So...... one of my " to do " list items is - to
make
two small header tanks - with bubble release lines - on each fuel
line
just as they go vertically down after leaving the tank outlets

These two small header tanks ( about two litres capacity each )
will
have sight glasses on them themselves and will release any
bubbles
back to the fuel tank - through the top elbow connection of the
sight
tube

This means that you will always be able to tell when you're down
to the
last couple of litres - LITERALLY .... and that you won't get
any
bubbles in the fuel lines .. ( something I really want to avoid
with a
fuel injected engine ! )

Rick Harper
541 R


----- Original Message -----
From: WALTER KLATT
To: rebel-builders@dcsol.com
Sent: Thursday, December 16, 2004 3:52 AM
Subject: Re: RE: RE: Rebel Fuel Management


Sorry, my question is what is the lowest fuel level of the tank
that
you are switching to, not the one you are draining? For example, 5
g is
still legal by day, and have you ever done it that low? I would
suspect
not, but how low. The danger I see still is getting air bubbles
into the
line when it is low due to turbulence, etc. and fuel flow stopping
as
described by Phil. That's why I am asking.

Walter

----- Original Message -----
From: Drew Dalgleish <drewjan@cabletv.on.ca>
Date: Wednesday, December 15, 2004 6:27 am
Subject: RE: RE: Rebel Fuel Management
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[Ken]

I personally still believe in draining a tank completely if fuel is
tight but I understand that there are pros and cons.

As far as point #3 goes I don't see why it would makes any significant
difference where the fuel valves are located assuming they are properly
sized. I am a definate believer in vented header tanks however and would
prefer such a passive solution over a fuel pump. I'm still a little
leery of a fuel flow transducer in a gravity feed only system and mogas
in that would not help the discomfort.

Mogas does vapourize easier. It forms bubbles easier. More of it
vapourizes immediately at the carb so that the carb runs cooler than
with avgas. The risk of carb ice is higher. That's a separate issue than
air bubbles though. I like mogas and believe it saves maintanance
dollars as well as being easier on the wallet and the environment. I
guess some guys do prefer to keep avgas in one tank for takeoffs and I
guess that probably would slightly reduce the chance of vapour bubbles
on hot days.

Ken

WALTER KLATT wrote:

Yes, it has been quite an interesting discussion for me. We've been

over some of this before on the list, but this time I think I've
actually learned a few new things, that for some reason weren't getting
through my thick skull before. Perhaps I might recap some of these, and
anyone please correct me again, if I get it wrong. I take fuel
management very seriously, and while I have never been close to running
out so far, and don't intend to, but if I ever do get into an
inadvertant low fuel situation, I want to be sure that I don't take any
wrong actions that might risk my butt further. So here is what I have
learned:

1. If you do run a tank dry, do not close the empty tank before

opening the new one and before the engine has resumed power. Also, I
would open the primer briefly and let the engine suck out the air from
the gascolator, and give it a few pumps until I feel it squirting fuel
or the engine roughens from the overly rich mixture in the cylinders.
Then do a brief full power climb as a final confirmation.

2. If you do get real low on fuel, keep running on both, even right to

the last drop. If one tank runs dry first, it will not mean immediate
engine stoppage, as long as there is still some fuel in the other tank.
Previously, I would have thought it was best to run one tank dry, and
then switch to the fuller one for the final stretch. I will still switch
tanks to balance them or if I have mogas or avgas that I am using up,
but when both tanks are low, both valves will be open.

3. If building again, I might consider having my two fuel valves or a

selector at floor level instead of only up top on the tank outlets. That
way I will never have air trapped in my lines and a full 3 foot gravity
head always available to get the fuel moving immediately after switching
from an empty tank. I still might want the fuel shut-offs also on top,
for emergency purposes, such as an accident to keep fuel out of the cabin.

These were the main points for me. If anyone disagrees, I would sure

like to hear it and why. As the saying goes, it's not just what you know
that will hurt you, but what you know that ain't so.

Rick and Phil have suggested some mods with header tanks and bubble

removers, which can only help further. But since my engine is not fuel
injected and does not require fuel pressure for the carb, I'm still OK
with the current set-up.

Of course, all of this does not take the place of good fuel management

using your watch and knowing your fuel flow. I also have the sight
gauges not connected to the fuel outlets, and a fuel flow monitor. I
really like the fuel flow monitor, as I have always found it to be
totally accurate. And I know my exact fuel flow at any given time.

Thanks to all who contributed.

Walter


----- Original Message -----
From: Rick Harper <rjwh@optusnet.com.au>
Date: Wednesday, December 15, 2004 1:32 pm
Subject: Re: RE: RE: Rebel Fuel Management

G'day from OZ Walter ....

I have been following your e-mails regarding fuel management
with a
fair amount of interest as I nearly did it to myself - ( ran out
of fuel
), a few years back - when we were using an 0-235 .
( I might point out that this time that the problem was all my own
doing
....not paying enough attention to fuel management while
entertaining a
friend (a fellow Rebel builder visiting from America ) - and
encountering several unplanned alterations to our flight )

I realized very early on in the piece that the original MAM
system of
having a vertical sight tube meant that you couldn't tell what the
fuel
level was (by about 30 litres in each tank ), once the fuel level
got
down to the bottom sight glass elbow - something that I really
didn't
like ......

So I moved the bottom of the sight glass / tube to be common with
the
fuel outlet ( which is what everyone is saying you should not do )
....
BUT because the sight tube is now twice as long and diagonal - the
readings I get are very accurate - something I really do like !!!

(I filled each tank five litres at a time and marked the fuel
position
within tube on the back side of the tube - for when the plane was
on the
ground, and the front side of the tube- for when the plane was in
the
flying attitude .... so the gauge is dead accurate whether the
plane
is on the ground or in the air !)

As for the problem of the sight tube allowing air to enter the
fuel line
.... this IS only a problem when the fuel level gets very low -
and in
turbulence .... So...... one of my " to do " list items is - to
make
two small header tanks - with bubble release lines - on each fuel
line
just as they go vertically down after leaving the tank outlets

These two small header tanks ( about two litres capacity each )
will
have sight glasses on them themselves and will release any
bubbles
back to the fuel tank - through the top elbow connection of the
sight
tube

This means that you will always be able to tell when you're down
to the
last couple of litres - LITERALLY .... and that you won't get
any
bubbles in the fuel lines .. ( something I really want to avoid
with a
fuel injected engine ! )

Rick Harper
541 R


----- Original Message -----
From: WALTER KLATT
To: rebel-builders@dcsol.com
Sent: Thursday, December 16, 2004 3:52 AM
Subject: Re: RE: RE: Rebel Fuel Management


Sorry, my question is what is the lowest fuel level of the tank
that
you are switching to, not the one you are draining? For example, 5
g is
still legal by day, and have you ever done it that low? I would
suspect
not, but how low. The danger I see still is getting air bubbles
into the
line when it is low due to turbulence, etc. and fuel flow stopping
as
described by Phil. That's why I am asking.

Walter

----- Original Message -----
From: Drew Dalgleish <drewjan@cabletv.on.ca>
Date: Wednesday, December 15, 2004 6:27 am
Subject: RE: RE: Rebel Fuel Management

At 04:55 PM 12/14/2004 -0800, you wrote: I empty my tank completly by flying with one wing slightly low
Drew





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[Walter Klatt]

Ted, the primer line is connected to the top of the gascolator,
and as Wayne mentioned in a previous message, it would allow the
air to escape and be sucked out so that the gascolator is just
full of fuel, with no trapped air pocket. As far as pulling it
out in flight, if you guys remember about a year and half ago, I
had that weird problem where my primer wasn't closing properly
because of some dirt. Anyway, at that time, one of my attempted
remedies was to pull the primer in flight, so that's why I have
no fear of doing that now. I haven't done it since, but still
remember what happened then. This step probably isn't necessary,
but I may try it anyway next time I fly just to see again how it
works. Doing a short full power climb with a brief nose high
attitude should probably suffice to force any air out of the
gascolator.

For a carb engine, I don't see the need for a fuel pump, just
extra cost, complexity, and weight. I think the gravity feed
system works just fine, as long you know what you are doing,
which is why I wanted this discussion. In fact with a fuel pump,
the procedures that I just described for running a tank dry would
not apply, and might even be detrimental. A gravity feed system
pushes fuel down through the lines, while a pump would pull. And
if you had both valves open, and one tank was empty, it might
just pull air from the empty tank as that is the path of least
resistance. Not exactly sure about that, but it certainly would
be something that I would need to understand and test. If you
want to use a fuel pump, I would think that you might want two,
each mounted up top by the tank outlets. But that's a whole
different ball game, and I don't feel qualified to discuss that
one.

Ken, you asked why I thought valves on the bottom would be
better. With the valves up top, if you are not running on both,
and then run one tank dry, both lines will be completely empty of
fuel then, and therefore full of air. Because we rely on gravity
feed, the new tank will not start feeding as quickly because it
has to first fill the line and push out the air through the
gascolator, fuel flow sender (in my case) and then the carb bowl.
But if the valves are at the bottom, then the line with the full
tank will always be full of fuel, so that as soon as you open it,
you will have your full 3 feet of gravity fuel head available
immediately to push fuel through to the carb.

As for the fuel flow transducer, I was leery about it as well at
first, but my fuel flow tests were still adequate (150% of max
flow). I am however using a Floscan model (can't remember the
part number) that was made specifically for low pressure gravity
feed systems. Again, I will say that is probably my favourite
instrument on my panel, as it measures flow to one decimal place,
and allows me to very accurately manage my fuel and times. Also,
I can lean very accurately. And if any of my instruments (also
have electronic 4 cht, 4 egt) don't jive from what I know they
should be at a given rpm, altitude, speed, etc, I know something
isn't right (like carb ice), long before you would notice a power
loss or engine roughness. Because I fly a lot in the mountains, I
keep a really close eye on these when I'm over hostile terrain.

I also agree that vented header tanks are the ultimate solution,
but still believe they are not necessary for my set-up. And
again, I don't like the weight and complexity.

Of course we all have to make up our own minds with these
choices. The important thing is that we understand what we are
doing, and not make any blind mistakes, because of ignorance.
That's what I was worried about in my case when I didn't fully
understand what was happening as described in my first message of
the thread.

Walter

-----Original Message-----
From: mike.davis@dcsol.com
[mailto:mike.davis@dcsol.com]On Behalf Of Ted
I Weitz
Sent: Wednesday, December 15, 2004 6:08 PM
To: rebel-builders@dcsol.com
Subject: Re: RE: RE: Rebel Fuel Management


Walter,

thanks for bringing up the subject, great to learn
from this discussion.

I didn't understand the primer stuff you wrote. Do
you see the engine
sucking the air to clear the line while providing the
needed fuel with the
primer?

What do you and the group think on adding an electric
fuel pump down the
line. Always thought that having a pump will provide
some insurance as it
can force the fuel through some bad stuff including
air, dirt, sloshing
particles etc.

The other thing is my mistrust of plain gravity feeds
at a very low fuel
level and some unusual attitude and high Gs

What do you think?

Ted
----- Original Message -----
From: "WALTER KLATT" <Walter.Klatt@shaw.ca>
To: <rebel-builders@dcsol.com>
Sent: Wednesday, December 15, 2004 6:38 PM
Subject: Re: RE: RE: Rebel Fuel Management

Yes, it has been quite an interesting discussion for

me. We've been over
some of this before on the list, but this time I think
I've actually learned
a few new things, that for some reason weren't getting
through my thick
skull before. Perhaps I might recap some of these, and
anyone please correct
me again, if I get it wrong. I take fuel management
very seriously, and
while I have never been close to running out so far,
and don't intend to,
but if I ever do get into an inadvertant low fuel
situation, I want to be
sure that I don't take any wrong actions that might
risk my butt further. So
here is what I have learned:

1. If you do run a tank dry, do not close the empty

tank before opening
the new one and before the engine has resumed power.
Also, I would open the
primer briefly and let the engine suck out the air
from the gascolator, and
give it a few pumps until I feel it squirting fuel or
the engine roughens
from the overly rich mixture in the cylinders. Then do
a brief full power
climb as a final confirmation.

2. If you do get real low on fuel, keep running on

both, even right to the
last drop. If one tank runs dry first, it will not
mean immediate engine
stoppage, as long as there is still some fuel in the
other tank. Previously,
I would have thought it was best to run one tank dry,
and then switch to the
fuller one for the final stretch. I will still switch
tanks to balance them
or if I have mogas or avgas that I am using up, but
when both tanks are low,
both valves will be open.

3. If building again, I might consider having my two

fuel valves or a
selector at floor level instead of only up top on the
tank outlets. That way
I will never have air trapped in my lines and a full 3
foot gravity head
always available to get the fuel moving immediately
after switching from an
empty tank. I still might want the fuel shut-offs also
on top, for emergency
purposes, such as an accident to keep fuel out of the cabin.

These were the main points for me. If anyone

disagrees, I would sure like
to hear it and why. As the saying goes, it's not just
what you know that
will hurt you, but what you know that ain't so.

Rick and Phil have suggested some mods with header

tanks and bubble
removers, which can only help further. But since my
engine is not fuel
injected and does not require fuel pressure for the
carb, I'm still OK with
the current set-up.

Of course, all of this does not take the place of

good fuel management
using your watch and knowing your fuel flow. I also
have the sight gauges
not connected to the fuel outlets, and a fuel flow
monitor. I really like
the fuel flow monitor, as I have always found it to be
totally accurate.
And I know my exact fuel flow at any given time.

Thanks to all who contributed.

Walter


----- Original Message -----
From: Rick Harper <rjwh@optusnet.com.au>
Date: Wednesday, December 15, 2004 1:32 pm
Subject: Re: RE: RE: Rebel Fuel Management

G'day from OZ Walter ....

I have been following your e-mails regarding

fuel management

with a
fair amount of interest as I nearly did it to

myself - ( ran out

of fuel
), a few years back - when we were using an 0-235 .
( I might point out that this time that the

problem was all my own

doing
....not paying enough attention to fuel management while
entertaining a
friend (a fellow Rebel builder visiting from

America ) - and

encountering several unplanned alterations to our flight )

I realized very early on in the piece that the

original MAM

system of
having a vertical sight tube meant that you

couldn't tell what the

fuel
level was (by about 30 litres in each tank ), once

the fuel level

got
down to the bottom sight glass elbow - something

that I really

didn't
like ......

So I moved the bottom of the sight glass / tube to

be common with

the
fuel outlet ( which is what everyone is saying you

should not do )

....
BUT because the sight tube is now twice as long

and diagonal - the

readings I get are very accurate - something I

really do like !!!

(I filled each tank five litres at a time and

marked the fuel

position
within tube on the back side of the tube - for

when the plane was

on the
ground, and the front side of the tube- for when

the plane was in

the
flying attitude .... so the gauge is dead

accurate whether the

plane
is on the ground or in the air !)

As for the problem of the sight tube allowing air

to enter the

fuel line
.... this IS only a problem when the fuel level

gets very low -

and in
turbulence .... So...... one of my " to do " list

items is - to

make
two small header tanks - with bubble release

lines - on each fuel

line
just as they go vertically down after leaving the

tank outlets

These two small header tanks ( about two litres

capacity each )

will
have sight glasses on them themselves and will

release any

bubbles
back to the fuel tank - through the top elbow

connection of the

sight
tube

This means that you will always be able to tell

when you're down

to the
last couple of litres - LITERALLY .... and that

you won't get

any
bubbles in the fuel lines .. ( something I really

want to avoid

with a
fuel injected engine ! )

Rick Harper
541 R


----- Original Message -----
From: WALTER KLATT
To: rebel-builders@dcsol.com
Sent: Thursday, December 16, 2004 3:52 AM
Subject: Re: RE: RE: Rebel Fuel Management


Sorry, my question is what is the lowest fuel

level of the tank

that
you are switching to, not the one you are

draining? For example, 5

g is
still legal by day, and have you ever done it that

low? I would

suspect
not, but how low. The danger I see still is

getting air bubbles

into the
line when it is low due to turbulence, etc. and

fuel flow stopping

as
described by Phil. That's why I am asking.

Walter

----- Original Message -----
From: Drew Dalgleish <drewjan@cabletv.on.ca>
Date: Wednesday, December 15, 2004 6:27 am
Subject: RE: RE: Rebel Fuel Management

And what is the

have had prior to

wing slightly low

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