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[rebel-builders] header tank

Converted from Wildcat! database. (read only)
Ken

[rebel-builders] header tank

Post by Ken » Sun Feb 19, 2012 11:35 pm

Paul

General rules for a header is to return any fuel above the exit point to
the engine if it is a system that bypasses fuel. ie don't re-ingest the
vapour bubbles.

Yes my header is vented from as high up as I could easily plumb into and
the vent goes back to the cross vent line that connects between the top
of the two wing tanks. The connection is in the wing root. Ideally a
vent line will slope up all the way to the exit point. My header is on
the wall behind my seat and is always full unless I turn off the wing
tank outlets to test the float gauge that is in my header. It is not
trivial to put a header in the fuselage that will withstand a crash
though. It might be safer to locate one under the floor or forward of
the firewall or to use Phil's mod that I mention in another post this
morning.

A header tank could be nothing more than very large diameter tubing in
the vertical fuel line if plumbed such that bubbles can get back to the
tank and water can make its way to the gascolator.

Depends on the inspector I suppose but Canada's inspection agency is on
record as saying that a header with a water drain can take the place of
a gascolator. They probably want some kind of strainer or filter in the
system though.

Ken
119R

On 03/12/2011 4:44 PM, paul.lennemann@dcsol.com wrote:
A couple of questions regarding a header tank.

Do you need to run a fuel pump with a header tank, (elec. or mech.)?

When the engine is off, does the fuel equalize up the header vent to
the fuel level in the wings?

Do you need to create a high spot in the header tank to place the vent
or does the movement in flight push any air bubbles to the vent on a
flat top header tank? (Think filling frozen water trough when the hose
water breaks through the ice layer)

Does any one have any photos or sketches of a fuel system they can
post?

Thanks, Paul Lennemann SR074



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Bob Palmer

[rebel-builders] Header Tank

Post by Bob Palmer » Sun Feb 19, 2012 11:35 pm

Paul,

If I created confusion with my comments then I am sorry. The current
system as designed and depicted in your builders manual is the correct
system and should only be modified at your own discretion. It is my
personal opinion that Murphy's system might function a little better if
the system were modified slightly in order to avoid the potential for
fuel slopping (more accurately, sloshing) to introduce air into the
system. I am not recommending or instructing anything but imagine when
the fuel at a low level in the tank starts to slosh back and forth due
to aircraft movement it could start to uncover the outlet supply line to
the engine. The solution is to carry more fuel, but another solution
which might help reduce that effect might be to create a depression in
the aft corner of the tank and moving the supply line to the bottom of
that (obviously that can't be done because it would stick down below the
wing). The effect would be to prevent the fuel from uncovering the
outlet supply line for much longer.
The comment I made earlier was an alternate way to achieve the same
thing by creating a small tank just downstream of the outlet line for
the fuel to collect. The fuel would have to enter the top and exit the
bottom and this small tank would have to be vented out the top back up
to the top of the main tank. That is just one idea and another was
mentioned as under the seat header tank.

Bob.

On 12/3/2011 8:29 AM, paul.lennemann@dcsol.com wrote:
A couple of questions,

Do you run a fuel pump, either electric or mechanical, with the header
tank?

When the engine is off, I assume the fuel will equalize up the header
vent line to the level of the fuel in the wing tanks, unless you turn the
wing tanks off, am I thinking correctly?

When the engine is running, is the fuel in the vent line at that same
elevation as above?

Do you make a high spot in the header tank to plumb the vent tube
out of or does a flat top suffice for preventing a bubble on top? (i'm
picturing my cattle trough with a layer of ice on it when I fill it up. Air
gets trapped on the underside of the ice)

Could some photos or a drawing of the fuel system with a header
tank be posted please?

Thanks,
Paul SR074



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paul.lennemann

[rebel-builders] Header Tank

Post by paul.lennemann » Sun Feb 19, 2012 11:35 pm

On 12/4/2011 12:03 PM, rtpalmer@shaw.ca wrote to rebel-builders:

Thanks Bob, makes more sense to me now.

Paul



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ray

[rebel-builders] Header Tank

Post by ray » Sun Feb 19, 2012 11:35 pm

I,m thinking about dual tanks and gravity feed alot lately and although my
system has worked fine with one very notable exception I do not like
starting to worry about fuel stavation while still having usable fuel in
both tanks. I have the glass sight gauges mounted at an angle but they are
tee,d into the supply line.I want to throw out my idea for discussion. I ,m
thinking of using the passenger side tank as a main tank and the pilot side
as a aux tank with an electric transfer pump. This is to transfer all usable
fuel to one tank. My thinking is this deepens the fuel, reducing sloshing
and is easier to monitor. If I did a header tank I am thinking of some 1.5
inch diameter aluminum tubing.thickwall with a conical cap with vent at top.
This would mount vertical in the cabin as high and as long as practical and
be securely mounted and possibly even enclosed in some reinforced hose for
crash/leak protection. This would allow for some unporting and frothy fuel
to settle out. This is slightly more fuel in the cabin with me but is still
a gravity feed system. The aux tank could still fuction as a main tank by
opening the valve. My strategy right now is maximum fuel at all times and I
will fix the tee,d situation as my next priority. I also am running the four
blade warp in front of a 290 and I like it but have nothing to compare it
to,it pulls hard on takeoff ant top speed is about 110 mph Ray
----- Original Message -----
From: <paul.lennemann@dcsol.com>
To: <rebel-builders@dcsol.com>
Sent: Sunday, December 04, 2011 9:34 PM
Subject: Re: [rebel-builders] Header Tank

On 12/4/2011 12:03 PM, rtpalmer@shaw.ca wrote to rebel-builders:

Thanks Bob, makes more sense to me now.

Paul



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Eduardo Gutierrez Sosa

[rebel-builders] Header Tank

Post by Eduardo Gutierrez Sosa » Sun Feb 19, 2012 11:35 pm

Hi Paul: I have a 15 gallon header tank besides two 13 gallon wing tanks in
another home built high wing aircraft (non Murphy) which is the same.
Considering the 15 gallon header gives me around 1:30 hours flying time, I
use an electric low pressure auto fuel pump from a Subaru just to give me
the final gallon (If need be) which is barely above the carburettor float.
When the engine is off and the aircraft is not on level ground, the header
will cause one tank to fill onto the lower tank, so I have individual
shutoff valves to avoid this. I have a third shutoff valve from the header
to the carburettor, and on this line I have the Subaru pump with a check
valve to obtain positive pressure to the carburettor. I leave this pump on
during all flight conditions.
The vent lines will have a level about two thirds of the way to the wing
tank elevation, but I don't know why it won't go all the way.
There is no need to make a high spot in the header tank; the vents will be
at the highest spot on this header, and that should suffice. The fuel exits
the bottom of the header, although one very important consideration is that
this vent line will go to the highest spot on the wing tanks; usually this
is the outermost end of the tank (because the wings will normally have a
dihedral angle).
Sorry I don't know how to post drawings, regards, Eduardo


El 03/12/11 12:29, "paul.lennemann@dcsol.com" <paul.lennemann@dcsol.com>
escribi


Walter Klatt

[rebel-builders] Header Tank

Post by Walter Klatt » Sun Feb 19, 2012 11:35 pm

I think you guys are over-thinking the problem. In flight, if you want to
keep more fuel in one tank, so you can better watch it, or avoid letting in
air bubbles, you can always run one dry, and then open the good one, and
close the dry one. Just be sure to do it in that sequence, otherwise, you
will trap air in the line and your engine will quit.

Once you get really low, best to keep both tanks open, so you can't trap
air, and bubbles will always have a chance to escape.

But you should never be cutting it that close anyways. I think the lowest I
have ever run mine is down to about 7 gallons left between the two tanks. I
also was very aware of that, and was on a short 1/2 flight, back home from
my cabin. Besides the sight gauges, and checking with a dipstick, when I am
that low, I also have an accurate fuel monitor that tells me exactly what I
am using and have left.

In flight I have accidently killed my engine in fight, when switching tanks.
I did it after running on one tank, and instead of turning on the good tank,
shut the other one off (both closed), and after a few seconds the engine
quit. I quickly opened the tanks, and the engine fired right up again, no
problem.

The only thing you really have to worry about is trapping air, by closing
the empty tank first or too soon. Your engine will restart, but it won't
continue running, even with the good tank open. You must first open the good
tank, and be sure it is feeding and the engine running smoothly, before
closing the empty one.

And if you do go with one tank, be sure to have your fuel valve at the
bottom, not the top by the wing, as with the stock configuration. Because if
you only have one tank, with the valve on top, you could trap air. And with
no second tank and line, for the air to escape, you are running a much
bigger risk than for what you were originally worried about.

Walter

-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com] On Behalf Of ray
Sent: Monday, December 05, 2011 12:00 PM
To: rebel-builders@dcsol.com
Subject: Re: [rebel-builders] Header Tank

I,m thinking about dual tanks and gravity feed alot lately and although my
system has worked fine with one very notable exception I do not like
starting to worry about fuel stavation while still having usable fuel in
both tanks. I have the glass sight gauges mounted at an angle but they are
tee,d into the supply line.I want to throw out my idea for discussion. I ,m
thinking of using the passenger side tank as a main tank and the pilot side
as a aux tank with an electric transfer pump. This is to transfer all usable
fuel to one tank. My thinking is this deepens the fuel, reducing sloshing
and is easier to monitor. If I did a header tank I am thinking of some 1.5
inch diameter aluminum tubing.thickwall with a conical cap with vent at top.

This would mount vertical in the cabin as high and as long as practical and
be securely mounted and possibly even enclosed in some reinforced hose for
crash/leak protection. This would allow for some unporting and frothy fuel
to settle out. This is slightly more fuel in the cabin with me but is still
a gravity feed system. The aux tank could still fuction as a main tank by
opening the valve. My strategy right now is maximum fuel at all times and I
will fix the tee,d situation as my next priority. I also am running the four
blade warp in front of a 290 and I like it but have nothing to compare it
to,it pulls hard on takeoff ant top speed is about 110 mph Ray
----- Original Message -----
From: <paul.lennemann@dcsol.com>
To: <rebel-builders@dcsol.com>
Sent: Sunday, December 04, 2011 9:34 PM
Subject: Re: [rebel-builders] Header Tank

On 12/4/2011 12:03 PM, rtpalmer@shaw.ca wrote to rebel-builders:

Thanks Bob, makes more sense to me now.

Paul



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Ben Ransom

[rebel-builders] Header Tank

Post by Ben Ransom » Sun Feb 19, 2012 11:35 pm

Hi Walter,
Do you have a fuel selector valve mounted in the cabin, in addition to the
MAM shut-off gate valves at each wing root? If so, where is that mounted,
and are the lines from it to gascolator downhill?
Thanks,
-Ben

On 12/5/11 6:15 PM, "Walter Klatt" <Walter.Klatt@shaw.ca> wrote:
I think you guys are over-thinking the problem. In flight, if you want to
keep more fuel in one tank, so you can better watch it, or avoid letting
in
air bubbles, you can always run one dry, and then open the good one, and
close the dry one. Just be sure to do it in that sequence, otherwise, you
will trap air in the line and your engine will quit.

Once you get really low, best to keep both tanks open, so you can't trap
air, and bubbles will always have a chance to escape.

But you should never be cutting it that close anyways. I think the lowest
I
have ever run mine is down to about 7 gallons left between the two tanks.
I
also was very aware of that, and was on a short 1/2 flight, back home from
my cabin. Besides the sight gauges, and checking with a dipstick, when I
am
that low, I also have an accurate fuel monitor that tells me exactly what
I
am using and have left.

In flight I have accidently killed my engine in fight, when switching
tanks.
I did it after running on one tank, and instead of turning on the good
tank,
shut the other one off (both closed), and after a few seconds the engine
quit. I quickly opened the tanks, and the engine fired right up again, no
problem.

The only thing you really have to worry about is trapping air, by closing
the empty tank first or too soon. Your engine will restart, but it won't
continue running, even with the good tank open. You must first open the
good
tank, and be sure it is feeding and the engine running smoothly, before
closing the empty one.

And if you do go with one tank, be sure to have your fuel valve at the
bottom, not the top by the wing, as with the stock configuration. Because
if
you only have one tank, with the valve on top, you could trap air. And
with
no second tank and line, for the air to escape, you are running a much
bigger risk than for what you were originally worried about.

Walter

-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com] On Behalf Of ray
Sent: Monday, December 05, 2011 12:00 PM
To: rebel-builders@dcsol.com
Subject: Re: [rebel-builders] Header Tank

I,m thinking about dual tanks and gravity feed alot lately and although my
system has worked fine with one very notable exception I do not like
starting to worry about fuel stavation while still having usable fuel in
both tanks. I have the glass sight gauges mounted at an angle but they are
tee,d into the supply line.I want to throw out my idea for discussion. I
,m
thinking of using the passenger side tank as a main tank and the pilot
side
as a aux tank with an electric transfer pump. This is to transfer all
usable
fuel to one tank. My thinking is this deepens the fuel, reducing sloshing
and is easier to monitor. If I did a header tank I am thinking of some 1.5
inch diameter aluminum tubing.thickwall with a conical cap with vent at
top.

This would mount vertical in the cabin as high and as long as practical
and
be securely mounted and possibly even enclosed in some reinforced hose for
crash/leak protection. This would allow for some unporting and frothy fuel
to settle out. This is slightly more fuel in the cabin with me but is
still
a gravity feed system. The aux tank could still fuction as a main tank by
opening the valve. My strategy right now is maximum fuel at all times and
I
will fix the tee,d situation as my next priority. I also am running the
four
blade warp in front of a 290 and I like it but have nothing to compare it
to,it pulls hard on takeoff ant top speed is about 110 mph Ray
----- Original Message -----
From: <paul.lennemann@dcsol.com>
To: <rebel-builders@dcsol.com>
Sent: Sunday, December 04, 2011 9:34 PM
Subject: Re: [rebel-builders] Header Tank

On 12/4/2011 12:03 PM, rtpalmer@shaw.ca wrote to rebel-builders:

Thanks Bob, makes more sense to me now.

Paul



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Walter Klatt

[rebel-builders] Header Tank

Post by Walter Klatt » Sun Feb 19, 2012 11:35 pm

No, I just have the stock system with the two valves at the wing roots. Once
you understand the system, and how to prevent (and purge) trapped air, I am
good with it. Despite the added restriction at the gascolator with my fuel
flow sensor (floscan 231) and a 360 that can flow up to 18 gph at a very
steep climb angle (1800 fpm with low fuel), have never had a problem, as
long as there is no trapped air in the lines.

But if I had only one tank, then I would definitely want a fuel valve at the
bottom, on the floor somewhere. Otherwise, you would be running a very high
risk of trapping some air in your line (just checking for water in your
drains when your valve is closed could do it), and having your engine quit
at a very bad time, like right after take-off. Or even with low fuel, and
turbulence, you might get air sucked down by the fuel flow, and then get
trapped somewhere in your lines, resulting in your engine quitting. That's
why I don't like just one fuel line.

If I can remember, want to take a small level along on my next flight to
measure the in-flight angles, in particular, descent, to see when the rear
outlet might see air with low fuel.

Walter

-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com] On Behalf Of Ben
Ransom
Sent: Wednesday, December 07, 2011 9:42 AM
To: rebel-builders@dcsol.com
Subject: Re: [rebel-builders] Header Tank

Hi Walter,
Do you have a fuel selector valve mounted in the cabin, in addition to the
MAM shut-off gate valves at each wing root? If so, where is that mounted,
and are the lines from it to gascolator downhill?
Thanks,
-Ben

On 12/5/11 6:15 PM, "Walter Klatt" <Walter.Klatt@shaw.ca> wrote:
I think you guys are over-thinking the problem. In flight, if you want
to keep more fuel in one tank, so you can better watch it, or avoid
letting in air bubbles, you can always run one dry, and then open the
good one, and close the dry one. Just be sure to do it in that
sequence, otherwise, you will trap air in the line and your engine will
quit.

Once you get really low, best to keep both tanks open, so you can't
trap air, and bubbles will always have a chance to escape.

But you should never be cutting it that close anyways. I think the
lowest I have ever run mine is down to about 7 gallons left between the
two tanks.
I
also was very aware of that, and was on a short 1/2 flight, back home
from my cabin. Besides the sight gauges, and checking with a dipstick,
when I am that low, I also have an accurate fuel monitor that tells me
exactly what I am using and have left.

In flight I have accidently killed my engine in fight, when switching
tanks.
I did it after running on one tank, and instead of turning on the good
tank, shut the other one off (both closed), and after a few seconds the
engine quit. I quickly opened the tanks, and the engine fired right up
again, no problem.

The only thing you really have to worry about is trapping air, by
closing the empty tank first or too soon. Your engine will restart, but
it won't continue running, even with the good tank open. You must first
open the good tank, and be sure it is feeding and the engine running
smoothly, before closing the empty one.

And if you do go with one tank, be sure to have your fuel valve at the
bottom, not the top by the wing, as with the stock configuration.
Because if you only have one tank, with the valve on top, you could
trap air. And with no second tank and line, for the air to escape, you
are running a much bigger risk than for what you were originally
worried about.

Walter

-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com] On Behalf Of
ray
Sent: Monday, December 05, 2011 12:00 PM
To: rebel-builders@dcsol.com
Subject: Re: [rebel-builders] Header Tank

I,m thinking about dual tanks and gravity feed alot lately and although
my system has worked fine with one very notable exception I do not like
starting to worry about fuel stavation while still having usable fuel
in both tanks. I have the glass sight gauges mounted at an angle but
they are tee,d into the supply line.I want to throw out my idea for
discussion. I ,m thinking of using the passenger side tank as a main
tank and the pilot side as a aux tank with an electric transfer pump.
This is to transfer all usable fuel to one tank. My thinking is this
deepens the fuel, reducing sloshing and is easier to monitor. If I did
a header tank I am thinking of some 1.5 inch diameter aluminum
tubing.thickwall with a conical cap with vent at top.

This would mount vertical in the cabin as high and as long as practical
and be securely mounted and possibly even enclosed in some reinforced
hose for crash/leak protection. This would allow for some unporting and
frothy fuel to settle out. This is slightly more fuel in the cabin with
me but is still a gravity feed system. The aux tank could still fuction
as a main tank by opening the valve. My strategy right now is maximum
fuel at all times and I will fix the tee,d situation as my next
priority. I also am running the four blade warp in front of a 290 and I
like it but have nothing to compare it
to,it pulls hard on takeoff ant top speed is about 110 mph Ray
----- Original Message -----
From: <paul.lennemann@dcsol.com>
To: <rebel-builders@dcsol.com>
Sent: Sunday, December 04, 2011 9:34 PM
Subject: Re: [rebel-builders] Header Tank

On 12/4/2011 12:03 PM, rtpalmer@shaw.ca wrote to rebel-builders:

Thanks Bob, makes more sense to me now.

Paul



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Ben Ransom

[rebel-builders] Header Tank

Post by Ben Ransom » Sun Feb 19, 2012 11:35 pm

Thanks for that clarification Walter. I had never realized how nasty air
bubbles were to a Lyc carb, and still a little surprised the float bowl
can't buffer these sort of things. Nonetheless, hopefully I'll remember
this stuff when I get to that stage!
Cheers,
-Ben

On 12/7/11 10:29 AM, "Walter Klatt" <Walter.Klatt@shaw.ca> wrote:
No, I just have the stock system with the two valves at the wing roots.
Once
you understand the system, and how to prevent (and purge) trapped air, I
am
good with it. Despite the added restriction at the gascolator with my fuel
flow sensor (floscan 231) and a 360 that can flow up to 18 gph at a very
steep climb angle (1800 fpm with low fuel), have never had a problem, as
long as there is no trapped air in the lines.

But if I had only one tank, then I would definitely want a fuel valve at
the
bottom, on the floor somewhere. Otherwise, you would be running a very
high
risk of trapping some air in your line (just checking for water in your
drains when your valve is closed could do it), and having your engine quit
at a very bad time, like right after take-off. Or even with low fuel, and
turbulence, you might get air sucked down by the fuel flow, and then get
trapped somewhere in your lines, resulting in your engine quitting. That's
why I don't like just one fuel line.

If I can remember, want to take a small level along on my next flight to
measure the in-flight angles, in particular, descent, to see when the rear
outlet might see air with low fuel.

Walter

-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com] On Behalf Of Ben
Ransom
Sent: Wednesday, December 07, 2011 9:42 AM
To: rebel-builders@dcsol.com
Subject: Re: [rebel-builders] Header Tank

Hi Walter,
Do you have a fuel selector valve mounted in the cabin, in addition to the
MAM shut-off gate valves at each wing root? If so, where is that mounted,
and are the lines from it to gascolator downhill?
Thanks,
-Ben

On 12/5/11 6:15 PM, "Walter Klatt" <Walter.Klatt@shaw.ca> wrote:
I think you guys are over-thinking the problem. In flight, if you want
to keep more fuel in one tank, so you can better watch it, or avoid
letting in air bubbles, you can always run one dry, and then open the
good one, and close the dry one. Just be sure to do it in that
sequence, otherwise, you will trap air in the line and your engine will
quit.

Once you get really low, best to keep both tanks open, so you can't
trap air, and bubbles will always have a chance to escape.

But you should never be cutting it that close anyways. I think the
lowest I have ever run mine is down to about 7 gallons left between the
two tanks.
I
also was very aware of that, and was on a short 1/2 flight, back home
from my cabin. Besides the sight gauges, and checking with a dipstick,
when I am that low, I also have an accurate fuel monitor that tells me
exactly what I am using and have left.

In flight I have accidently killed my engine in fight, when switching
tanks.
I did it after running on one tank, and instead of turning on the good
tank, shut the other one off (both closed), and after a few seconds the
engine quit. I quickly opened the tanks, and the engine fired right up
again, no problem.

The only thing you really have to worry about is trapping air, by
closing the empty tank first or too soon. Your engine will restart, but
it won't continue running, even with the good tank open. You must first
open the good tank, and be sure it is feeding and the engine running
smoothly, before closing the empty one.

And if you do go with one tank, be sure to have your fuel valve at the
bottom, not the top by the wing, as with the stock configuration.
Because if you only have one tank, with the valve on top, you could
trap air. And with no second tank and line, for the air to escape, you
are running a much bigger risk than for what you were originally
worried about.

Walter

-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com] On Behalf Of
ray
Sent: Monday, December 05, 2011 12:00 PM
To: rebel-builders@dcsol.com
Subject: Re: [rebel-builders] Header Tank

I,m thinking about dual tanks and gravity feed alot lately and although
my system has worked fine with one very notable exception I do not like
starting to worry about fuel stavation while still having usable fuel
in both tanks. I have the glass sight gauges mounted at an angle but
they are tee,d into the supply line.I want to throw out my idea for
discussion. I ,m thinking of using the passenger side tank as a main
tank and the pilot side as a aux tank with an electric transfer pump.
This is to transfer all usable fuel to one tank. My thinking is this
deepens the fuel, reducing sloshing and is easier to monitor. If I did
a header tank I am thinking of some 1.5 inch diameter aluminum
tubing.thickwall with a conical cap with vent at top.

This would mount vertical in the cabin as high and as long as practical
and be securely mounted and possibly even enclosed in some reinforced
hose for crash/leak protection. This would allow for some unporting and
frothy fuel to settle out. This is slightly more fuel in the cabin with
me but is still a gravity feed system. The aux tank could still fuction
as a main tank by opening the valve. My strategy right now is maximum
fuel at all times and I will fix the tee,d situation as my next
priority. I also am running the four blade warp in front of a 290 and I
like it but have nothing to compare it
to,it pulls hard on takeoff ant top speed is about 110 mph Ray
----- Original Message -----
From: <paul.lennemann@dcsol.com>
To: <rebel-builders@dcsol.com>
Sent: Sunday, December 04, 2011 9:34 PM
Subject: Re: [rebel-builders] Header Tank

On 12/4/2011 12:03 PM, rtpalmer@shaw.ca wrote to rebel-builders:

Thanks Bob, makes more sense to me now.

Paul



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Ben Ransom

[rebel-builders] Header Tank

Post by Ben Ransom » Sun Feb 19, 2012 11:35 pm

Bringing in Walter's advice not to over-complicate, the simpler version of
your idea Ray might be to just be in the habit of always using up left
tank first. (no transfer pump)

From the discussion I've wondered about using larger diameter fuel line.
This wouldn't prevent trapped air problems from pilot error in changing
tanks. But it might prevent the air bubble problem ...and heck, that way I
could consider my fuel lines a small header tank!
-Ben

On 12/5/11 11:59 AM, "ray" <raybot@comcast.net> wrote:
I,m thinking about dual tanks and gravity feed alot lately and although
my
system has worked fine with one very notable exception I do not like
starting to worry about fuel stavation while still having usable fuel in
both tanks. I have the glass sight gauges mounted at an angle but they
are
tee,d into the supply line.I want to throw out my idea for discussion. I
,m
thinking of using the passenger side tank as a main tank and the pilot
side
as a aux tank with an electric transfer pump. This is to transfer all
usable
fuel to one tank. My thinking is this deepens the fuel, reducing sloshing
and is easier to monitor. If I did a header tank I am thinking of some
1.5
inch diameter aluminum tubing.thickwall with a conical cap with vent at
top.
This would mount vertical in the cabin as high and as long as practical
and
be securely mounted and possibly even enclosed in some reinforced hose
for
crash/leak protection. This would allow for some unporting and frothy
fuel
to settle out. This is slightly more fuel in the cabin with me but is
still
a gravity feed system. The aux tank could still fuction as a main tank by
opening the valve. My strategy right now is maximum fuel at all times and
I
will fix the tee,d situation as my next priority. I also am running the
four
blade warp in front of a 290 and I like it but have nothing to compare it
to,it pulls hard on takeoff ant top speed is about 110 mph Ray
----- Original Message -----
From: <paul.lennemann@dcsol.com>
To: <rebel-builders@dcsol.com>
Sent: Sunday, December 04, 2011 9:34 PM
Subject: Re: [rebel-builders] Header Tank

On 12/4/2011 12:03 PM, rtpalmer@shaw.ca wrote to rebel-builders:

Thanks Bob, makes more sense to me now.

Paul



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Walter Klatt

[rebel-builders] Header Tank

Post by Walter Klatt » Sun Feb 19, 2012 11:35 pm

No, the carb can handle the bubbles. It's fuel line where they get stuck
fighting their way back up against the fuel flow.

Walter

-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com] On Behalf Of Ben
Ransom
Sent: Thursday, December 08, 2011 9:47 PM
To: rebel-builders@dcsol.com
Subject: Re: [rebel-builders] Header Tank

Thanks for that clarification Walter. I had never realized how nasty air
bubbles were to a Lyc carb, and still a little surprised the float bowl
can't buffer these sort of things. Nonetheless, hopefully I'll remember
this stuff when I get to that stage!
Cheers,
-Ben

On 12/7/11 10:29 AM, "Walter Klatt" <Walter.Klatt@shaw.ca> wrote:
No, I just have the stock system with the two valves at the wing roots.
Once
you understand the system, and how to prevent (and purge) trapped air,
I am good with it. Despite the added restriction at the gascolator with
my fuel flow sensor (floscan 231) and a 360 that can flow up to 18 gph
at a very steep climb angle (1800 fpm with low fuel), have never had a
problem, as long as there is no trapped air in the lines.

But if I had only one tank, then I would definitely want a fuel valve
at the bottom, on the floor somewhere. Otherwise, you would be running
a very high risk of trapping some air in your line (just checking for
water in your drains when your valve is closed could do it), and having
your engine quit at a very bad time, like right after take-off. Or even
with low fuel, and turbulence, you might get air sucked down by the
fuel flow, and then get trapped somewhere in your lines, resulting in
your engine quitting. That's why I don't like just one fuel line.

If I can remember, want to take a small level along on my next flight
to measure the in-flight angles, in particular, descent, to see when
the rear outlet might see air with low fuel.

Walter

-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com] On Behalf Of
Ben Ransom
Sent: Wednesday, December 07, 2011 9:42 AM
To: rebel-builders@dcsol.com
Subject: Re: [rebel-builders] Header Tank

Hi Walter,
Do you have a fuel selector valve mounted in the cabin, in addition to
the MAM shut-off gate valves at each wing root? If so, where is that
mounted, and are the lines from it to gascolator downhill?
Thanks,
-Ben

On 12/5/11 6:15 PM, "Walter Klatt" <Walter.Klatt@shaw.ca> wrote:
I think you guys are over-thinking the problem. In flight, if you want
to keep more fuel in one tank, so you can better watch it, or avoid
letting in air bubbles, you can always run one dry, and then open the
good one, and close the dry one. Just be sure to do it in that
sequence, otherwise, you will trap air in the line and your engine
will quit.

Once you get really low, best to keep both tanks open, so you can't
trap air, and bubbles will always have a chance to escape.

But you should never be cutting it that close anyways. I think the
lowest I have ever run mine is down to about 7 gallons left between
the two tanks.
I
also was very aware of that, and was on a short 1/2 flight, back home
from my cabin. Besides the sight gauges, and checking with a dipstick,
when I am that low, I also have an accurate fuel monitor that tells me
exactly what I am using and have left.

In flight I have accidently killed my engine in fight, when switching
tanks.
I did it after running on one tank, and instead of turning on the good
tank, shut the other one off (both closed), and after a few seconds
the engine quit. I quickly opened the tanks, and the engine fired
right up again, no problem.

The only thing you really have to worry about is trapping air, by
closing the empty tank first or too soon. Your engine will restart,
but it won't continue running, even with the good tank open. You must
first open the good tank, and be sure it is feeding and the engine
running smoothly, before closing the empty one.

And if you do go with one tank, be sure to have your fuel valve at the
bottom, not the top by the wing, as with the stock configuration.
Because if you only have one tank, with the valve on top, you could
trap air. And with no second tank and line, for the air to escape, you
are running a much bigger risk than for what you were originally
worried about.

Walter

-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com] On Behalf Of
ray
Sent: Monday, December 05, 2011 12:00 PM
To: rebel-builders@dcsol.com
Subject: Re: [rebel-builders] Header Tank

I,m thinking about dual tanks and gravity feed alot lately and
although my system has worked fine with one very notable exception I
do not like starting to worry about fuel stavation while still having
usable fuel in both tanks. I have the glass sight gauges mounted at an
angle but they are tee,d into the supply line.I want to throw out my
idea for discussion. I ,m thinking of using the passenger side tank as
a main tank and the pilot side as a aux tank with an electric transfer
pump.
This is to transfer all usable fuel to one tank. My thinking is this
deepens the fuel, reducing sloshing and is easier to monitor. If I did
a header tank I am thinking of some 1.5 inch diameter aluminum
tubing.thickwall with a conical cap with vent at top.

This would mount vertical in the cabin as high and as long as
practical and be securely mounted and possibly even enclosed in some
reinforced hose for crash/leak protection. This would allow for some
unporting and frothy fuel to settle out. This is slightly more fuel in
the cabin with me but is still a gravity feed system. The aux tank
could still fuction as a main tank by opening the valve. My strategy
right now is maximum fuel at all times and I will fix the tee,d
situation as my next priority. I also am running the four blade warp
in front of a 290 and I like it but have nothing to compare it
to,it pulls hard on takeoff ant top speed is about 110 mph Ray
----- Original Message -----
From: <paul.lennemann@dcsol.com>
To: <rebel-builders@dcsol.com>
Sent: Sunday, December 04, 2011 9:34 PM
Subject: Re: [rebel-builders] Header Tank

On 12/4/2011 12:03 PM, rtpalmer@shaw.ca wrote to rebel-builders:

Thanks Bob, makes more sense to me now.

Paul



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Walter Klatt

[rebel-builders] Header Tank

Post by Walter Klatt » Sun Feb 19, 2012 11:35 pm

Yes, a larger fuel line would help with eliminating bubbles. I just don't
want to blow this issue out of proportion, though. It is important to
understand what can happen, but it is not something that I am concerned
about. You just need to know how to properly operate your aircraft and fuel
systems under all circumstances.

Walter

-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com] On Behalf Of Ben
Ransom
Sent: Thursday, December 08, 2011 9:56 PM
To: rebel-builders@dcsol.com
Subject: Re: [rebel-builders] Header Tank

Bringing in Walter's advice not to over-complicate, the simpler version of
your idea Ray might be to just be in the habit of always using up left tank
first. (no transfer pump)

From the discussion I've wondered about using larger diameter fuel line.
This wouldn't prevent trapped air problems from pilot error in changing
tanks. But it might prevent the air bubble problem ...and heck, that way I
could consider my fuel lines a small header tank!
-Ben

On 12/5/11 11:59 AM, "ray" <raybot@comcast.net> wrote:
I,m thinking about dual tanks and gravity feed alot lately and although
my system has worked fine with one very notable exception I do not like
starting to worry about fuel stavation while still having usable fuel
in both tanks. I have the glass sight gauges mounted at an angle but
they are tee,d into the supply line.I want to throw out my idea for
discussion. I ,m thinking of using the passenger side tank as a main
tank and the pilot side as a aux tank with an electric transfer pump.
This is to transfer all usable fuel to one tank. My thinking is this
deepens the fuel, reducing sloshing and is easier to monitor. If I did
a header tank I am thinking of some
1.5
inch diameter aluminum tubing.thickwall with a conical cap with vent at
top.
This would mount vertical in the cabin as high and as long as practical
and be securely mounted and possibly even enclosed in some reinforced
hose for crash/leak protection. This would allow for some unporting and
frothy fuel to settle out. This is slightly more fuel in the cabin with
me but is still a gravity feed system. The aux tank could still fuction
as a main tank by opening the valve. My strategy right now is maximum
fuel at all times and I will fix the tee,d situation as my next
priority. I also am running the four blade warp in front of a 290 and I
like it but have nothing to compare it
to,it pulls hard on takeoff ant top speed is about 110 mph Ray
----- Original Message -----
From: <paul.lennemann@dcsol.com>
To: <rebel-builders@dcsol.com>
Sent: Sunday, December 04, 2011 9:34 PM
Subject: Re: [rebel-builders] Header Tank

On 12/4/2011 12:03 PM, rtpalmer@shaw.ca wrote to rebel-builders:

Thanks Bob, makes more sense to me now.

Paul



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Walter Klatt

[rebel-builders] Header Tank

Post by Walter Klatt » Sun Feb 19, 2012 11:35 pm

Just want to mention, too, that this discussion only applies to gravity feed
fuel systems with no engine or electric pump. A pump will suck through the
air. Although you can still have other issues like vapor lock.

Walter

-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com] On Behalf Of Walter
Klatt
Sent: Friday, December 09, 2011 6:22 AM
To: rebel-builders@dcsol.com
Subject: RE: [rebel-builders] Header Tank

Yes, a larger fuel line would help with eliminating bubbles. I just don't
want to blow this issue out of proportion, though. It is important to
understand what can happen, but it is not something that I am concerned
about. You just need to know how to properly operate your aircraft and fuel
systems under all circumstances.

Walter

-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com] On Behalf Of Ben
Ransom
Sent: Thursday, December 08, 2011 9:56 PM
To: rebel-builders@dcsol.com
Subject: Re: [rebel-builders] Header Tank

Bringing in Walter's advice not to over-complicate, the simpler version of
your idea Ray might be to just be in the habit of always using up left tank
first. (no transfer pump)

From the discussion I've wondered about using larger diameter fuel line.
This wouldn't prevent trapped air problems from pilot error in changing
tanks. But it might prevent the air bubble problem ...and heck, that way I
could consider my fuel lines a small header tank!
-Ben

On 12/5/11 11:59 AM, "ray" <raybot@comcast.net> wrote:
I,m thinking about dual tanks and gravity feed alot lately and although
my system has worked fine with one very notable exception I do not like
starting to worry about fuel stavation while still having usable fuel
in both tanks. I have the glass sight gauges mounted at an angle but
they are tee,d into the supply line.I want to throw out my idea for
discussion. I ,m thinking of using the passenger side tank as a main
tank and the pilot side as a aux tank with an electric transfer pump.
This is to transfer all usable fuel to one tank. My thinking is this
deepens the fuel, reducing sloshing and is easier to monitor. If I did
a header tank I am thinking of some
1.5
inch diameter aluminum tubing.thickwall with a conical cap with vent at
top.
This would mount vertical in the cabin as high and as long as practical
and be securely mounted and possibly even enclosed in some reinforced
hose for crash/leak protection. This would allow for some unporting and
frothy fuel to settle out. This is slightly more fuel in the cabin with
me but is still a gravity feed system. The aux tank could still fuction
as a main tank by opening the valve. My strategy right now is maximum
fuel at all times and I will fix the tee,d situation as my next
priority. I also am running the four blade warp in front of a 290 and I
like it but have nothing to compare it
to,it pulls hard on takeoff ant top speed is about 110 mph Ray
----- Original Message -----
From: <paul.lennemann@dcsol.com>
To: <rebel-builders@dcsol.com>
Sent: Sunday, December 04, 2011 9:34 PM
Subject: Re: [rebel-builders] Header Tank

On 12/4/2011 12:03 PM, rtpalmer@shaw.ca wrote to rebel-builders:

Thanks Bob, makes more sense to me now.

Paul



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Bob Palmer

[rebel-builders] Header Tank

Post by Bob Palmer » Sun Feb 19, 2012 11:35 pm

Walter,

I once had a particularly long flight in moderate turbulence in a Cessna
185. To make a long story short I had the engine quit twenty miles back
at about twelve hundred feet. Fortunately, the engine was restored at
about seven hundred feet. I also heard rumors that air in the lines was
strongly implicated in the crash of another C185.
However, that is not recreational flying because nobody has any fun in
moderate turbulence and nobody has any fun down close to the last thirty
minutes of fuel either. Hope we all just have fun!

Bob.

On 12/9/2011 7:25 AM, Walter Klatt wrote:
Just want to mention, too, that this discussion only applies to gravity feed
fuel systems with no engine or electric pump. A pump will suck through the
air. Although you can still have other issues like vapor lock.

Walter

-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com] On Behalf Of Walter
Klatt
Sent: Friday, December 09, 2011 6:22 AM
To: rebel-builders@dcsol.com
Subject: RE: [rebel-builders] Header Tank

Yes, a larger fuel line would help with eliminating bubbles. I just don't
want to blow this issue out of proportion, though. It is important to
understand what can happen, but it is not something that I am concerned
about. You just need to know how to properly operate your aircraft and fuel
systems under all circumstances.

Walter

-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com] On Behalf Of Ben
Ransom
Sent: Thursday, December 08, 2011 9:56 PM
To: rebel-builders@dcsol.com
Subject: Re: [rebel-builders] Header Tank

Bringing in Walter's advice not to over-complicate, the simpler version of
your idea Ray might be to just be in the habit of always using up left tank
first. (no transfer pump)
From the discussion I've wondered about using larger diameter fuel line.
This wouldn't prevent trapped air problems from pilot error in changing
tanks. But it might prevent the air bubble problem ...and heck, that way I
could consider my fuel lines a small header tank!
-Ben

On 12/5/11 11:59 AM, "ray"<raybot@comcast.net> wrote:
I,m thinking about dual tanks and gravity feed alot lately and although
my system has worked fine with one very notable exception I do not like
starting to worry about fuel stavation while still having usable fuel
in both tanks. I have the glass sight gauges mounted at an angle but
they are tee,d into the supply line.I want to throw out my idea for
discussion. I ,m thinking of using the passenger side tank as a main
tank and the pilot side as a aux tank with an electric transfer pump.
This is to transfer all usable fuel to one tank. My thinking is this
deepens the fuel, reducing sloshing and is easier to monitor. If I did
a header tank I am thinking of some
1.5
inch diameter aluminum tubing.thickwall with a conical cap with vent at
top.
This would mount vertical in the cabin as high and as long as practical
and be securely mounted and possibly even enclosed in some reinforced
hose for crash/leak protection. This would allow for some unporting and
frothy fuel to settle out. This is slightly more fuel in the cabin with
me but is still a gravity feed system. The aux tank could still fuction
as a main tank by opening the valve. My strategy right now is maximum
fuel at all times and I will fix the tee,d situation as my next
priority. I also am running the four blade warp in front of a 290 and I
like it but have nothing to compare it
to,it pulls hard on takeoff ant top speed is about 110 mph Ray
----- Original Message -----
From:<paul.lennemann@dcsol.com>
To:<rebel-builders@dcsol.com>
Sent: Sunday, December 04, 2011 9:34 PM
Subject: Re: [rebel-builders] Header Tank

On 12/4/2011 12:03 PM, rtpalmer@shaw.ca wrote to rebel-builders:

Thanks Bob, makes more sense to me now.

Paul



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Walter Klatt

[rebel-builders] Header Tank

Post by Walter Klatt » Sun Feb 19, 2012 11:35 pm

I am not familiar with 185 fuel systems (or many others). But as I
understand it, if you have a fuel pump, engine or electric going, it is the
opposite of gravity feed systems with how you select your tanks on low fuel.

IE, when on low fuel, you want to use only the tank with the most fuel. If
you have the empty one open, too, it can suck air from it instead of fuel
from the good one, and you could end up with a lot of air in your fuel
system.

I thought that certified systems usually don't have a Both in those
situations for that reason, just a Left and Right, and you need to manage
your tanks separately. At least that is how it was in the Cherokee 140 that
I used to fly, a long time ago.

Walter

-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com] On Behalf Of Bob
Palmer
Sent: Friday, December 09, 2011 9:28 AM
To: rebel-builders@dcsol.com
Subject: Re: [rebel-builders] Header Tank

Walter,

I once had a particularly long flight in moderate turbulence in a Cessna
185. To make a long story short I had the engine quit twenty miles back at
about twelve hundred feet. Fortunately, the engine was restored at about
seven hundred feet. I also heard rumors that air in the lines was strongly
implicated in the crash of another C185.
However, that is not recreational flying because nobody has any fun in
moderate turbulence and nobody has any fun down close to the last thirty
minutes of fuel either. Hope we all just have fun!

Bob.

On 12/9/2011 7:25 AM, Walter Klatt wrote:
Just want to mention, too, that this discussion only applies to
gravity feed fuel systems with no engine or electric pump. A pump will
suck through the air. Although you can still have other issues like vapor
lock.
Walter

-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com] On Behalf Of
Walter Klatt
Sent: Friday, December 09, 2011 6:22 AM
To: rebel-builders@dcsol.com
Subject: RE: [rebel-builders] Header Tank

Yes, a larger fuel line would help with eliminating bubbles. I just
don't want to blow this issue out of proportion, though. It is
important to understand what can happen, but it is not something that
I am concerned about. You just need to know how to properly operate
your aircraft and fuel systems under all circumstances.

Walter

-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com] On Behalf Of
Ben Ransom
Sent: Thursday, December 08, 2011 9:56 PM
To: rebel-builders@dcsol.com
Subject: Re: [rebel-builders] Header Tank

Bringing in Walter's advice not to over-complicate, the simpler
version of your idea Ray might be to just be in the habit of always
using up left tank first. (no transfer pump)
From the discussion I've wondered about using larger diameter fuel line.
This wouldn't prevent trapped air problems from pilot error in
changing tanks. But it might prevent the air bubble problem ...and
heck, that way I could consider my fuel lines a small header tank!
-Ben

On 12/5/11 11:59 AM, "ray"<raybot@comcast.net> wrote:
I,m thinking about dual tanks and gravity feed alot lately and
although my system has worked fine with one very notable exception I
do not like starting to worry about fuel stavation while still having
usable fuel in both tanks. I have the glass sight gauges mounted at
an angle but they are tee,d into the supply line.I want to throw out
my idea for discussion. I ,m thinking of using the passenger side
tank as a main tank and the pilot side as a aux tank with an electric
transfer pump.
This is to transfer all usable fuel to one tank. My thinking is this
deepens the fuel, reducing sloshing and is easier to monitor. If I
did a header tank I am thinking of some
1.5
inch diameter aluminum tubing.thickwall with a conical cap with vent
at top.
This would mount vertical in the cabin as high and as long as
practical and be securely mounted and possibly even enclosed in some
reinforced hose for crash/leak protection. This would allow for some
unporting and frothy fuel to settle out. This is slightly more fuel
in the cabin with me but is still a gravity feed system. The aux tank
could still fuction as a main tank by opening the valve. My strategy
right now is maximum fuel at all times and I will fix the tee,d
situation as my next priority. I also am running the four blade warp
in front of a 290 and I like it but have nothing to compare it
to,it pulls hard on takeoff ant top speed is about 110 mph Ray
----- Original Message -----
From:<paul.lennemann@dcsol.com>
To:<rebel-builders@dcsol.com>
Sent: Sunday, December 04, 2011 9:34 PM
Subject: Re: [rebel-builders] Header Tank

On 12/4/2011 12:03 PM, rtpalmer@shaw.ca wrote to rebel-builders:

Thanks Bob, makes more sense to me now.

Paul



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