The Murphy Builders Site

Yes returnless has some advantages but there are a lot of aspects to
this. High pressure pumps need to be either in the tank or immediately
below or beside the tank because they don't suck well or tolerate
bubbles well. I think that any of the injected Soobs could be run
returnless. Just put the pressure regulator in or beside the tank and
perhaps insulate the fuel rails. That's the way some or all of the Neons
do it. I don't consider it a problem to route high pressure fuel through
the cockpit but it is nice if the ecm shuts off the fuel after an engine
stoppage. They all do that if wired like the car. But then we often add
a second pump for takeoff and landing that will stay running (or in some
cases start running) after an engine stoppage...

With a header tank you can plumb low pressure gravity fed fuel into it.
Put the header forward of the firewall and then all the high pressure
fuel is out of the cockpit. Sounds attractive at first glance but then
perhaps the header fuel is in one of the worst places if there is a leak
or rupture in an accident. A small tank can be fairly robust and should
probably be mounted like in a car. No welded tabs to crack or break off
and leak. Just put a couple of bands around it. Assume the surrounding
structure will be deformed in an accident and leave room for the hoses
to flex and move a bit without being ripped off.

I'm also reminded of a statistic that Bob Knockoll's has mentioned. It
seems that there is seldom a post impact fire in light aircraft if the
battery is ejected by the impact. Battery ejection might be a tricky
design objective but it does seem wise to try and keep fuel away from
the electrics which are probably the most likely ignition source.

Happy New Year to all...
Ken


Bob Patterson wrote:

To each his own .... I've always disliked header tanks, ever
since I lost a good friend who was burned in a Super Cub crash
because the header tank split & sprayed gas all over him & the
burning engine ...

I know you did a lot of work to crash-proof yours, and I think
it's mounted in back, instead of on the firewall like the Cub,
but to me it's still extra work, & an added hazard, and besides,
I'm all in favour of "active fuel management" ;-) --- often
the lack of attention to the fuel status is what causes a lot
of silence, and an instant glider, at inconvenient times ! ;-) :-)

"Returnless EFI" - now THAT sounds like the ideal answer !!
It would be great if Subaru went that way !

......bobp

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Ken, Bob,
Thanks a lot for all your helpful information in this thread. I started my
Rebel with Soob in mind, then changed to thinking Lyc after about a year of
reading about the details of Soob conversion -- too much work for my blood,
and too hard to make low weight. But with higher fuel costs, and also seeing
how ultimate a Rebel can be even at 1060 empty, a Soob is back to a real
possibility for me.

Happy New Year everybody!
-Ben

On 12/31/2005 3:53 PM, klehman@albedo.net wrote to rebel-builders:

Yes returnless has some advantages but there are a lot of aspects to
this. High pressure pumps need to be either in the tank or immediately
below or beside the tank because they don't suck well or tolerate
bubbles well. I think that any of the injected Soobs could be run
returnless. Just put the pressure regulator in or beside the tank and
perhaps insulate the fuel rails. That's the way some or all of the Neons
do it. I don't consider it a problem to route high pressure fuel through
the cockpit but it is nice if the ecm shuts off the fuel after an engine
stoppage. They all do that if wired like the car. But then we often add
a second pump for takeoff and landing that will stay running (or in some
cases start running) after an engine stoppage...

With a header tank you can plumb low pressure gravity fed fuel into it.
Put the header forward of the firewall and then all the high pressure
fuel is out of the cockpit. Sounds attractive at first glance but then
perhaps the header fuel is in one of the worst places if there is a leak
or rupture in an accident. A small tank can be fairly robust and should
probably be mounted like in a car. No welded tabs to crack or break off
and leak. Just put a couple of bands around it. Assume the surrounding
structure will be deformed in an accident and leave room for the hoses
to flex and move a bit without being ripped off.

I'm also reminded of a statistic that Bob Knockoll's has mentioned. It
seems that there is seldom a post impact fire in light aircraft if the
battery is ejected by the impact. Battery ejection might be a tricky
design objective but it does seem wise to try and keep fuel away from
the electrics which are probably the most likely ignition source.

Happy New Year to all...
Ken


Bob Patterson wrote:

To each his own .... I've always disliked header tanks, ever
since I lost a good friend who was burned in a Super Cub crash
because the header tank split & sprayed gas all over him & the
burning engine ...

I know you did a lot of work to crash-proof yours, and I think
it's mounted in back, instead of on the firewall like the Cub,
but to me it's still extra work, & an added hazard, and besides,
I'm all in favour of "active fuel management" ;-) --- often
the lack of attention to the fuel status is what causes a lot
of silence, and an instant glider, at inconvenient times ! ;-) :-)

"Returnless EFI" - now THAT sounds like the ideal answer !!
It would be great if Subaru went that way !

......bobp

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Hi Ben !

The Soob can be a good choice - just one caution, though ...
don't even THINK about sending money to N__ ! I can put you in
touch with folks around the world who did - and got NOTHING !! :-(
(Apparently one or 2 people actually <got> engines ...)
Also avoid their CAP prop - our government transport dept. fingers
disintegration of these props for 2 major crashes ...

Often the "package" approach seems appealing - and it would be,
if someone did it right .... ;-) Look over the offerings
carefully - unfortunately, most likely, you are looking at doing
a large part of it yourself ... The good news is - there's
now a lot of good experience out there to draw on ! And some
very happy Soob powered Rebel drivers !!

......bobp

-------------------------------orig.-------------------------
On Sunday 01 January 2006 12:08 pm, bransom@dcsol.com wrote:

Ken, Bob,
Thanks a lot for all your helpful information in this thread. I started

my

Rebel with Soob in mind, then changed to thinking Lyc after about a year

of

reading about the details of Soob conversion -- too much work for my

blood,

and too hard to make low weight. But with higher fuel costs, and also

seeing

how ultimate a Rebel can be even at 1060 empty, a Soob is back to a real
possibility for me.

Happy New Year everybody!
-Ben

On 12/31/2005 3:53 PM, klehman@albedo.net wrote to rebel-builders:

Yes returnless has some advantages but there are a lot of aspects to
this. High pressure pumps need to be either in the tank or immediately
below or beside the tank because they don't suck well or tolerate
bubbles well. I think that any of the injected Soobs could be run
returnless. Just put the pressure regulator in or beside the tank and
perhaps insulate the fuel rails. That's the way some or all of the Neons
do it. I don't consider it a problem to route high pressure fuel through
the cockpit but it is nice if the ecm shuts off the fuel after an engine
stoppage. They all do that if wired like the car. But then we often add
a second pump for takeoff and landing that will stay running (or in some
cases start running) after an engine stoppage...

With a header tank you can plumb low pressure gravity fed fuel into it.
Put the header forward of the firewall and then all the high pressure
fuel is out of the cockpit. Sounds attractive at first glance but then
perhaps the header fuel is in one of the worst places if there is a leak
or rupture in an accident. A small tank can be fairly robust and should
probably be mounted like in a car. No welded tabs to crack or break off
and leak. Just put a couple of bands around it. Assume the surrounding
structure will be deformed in an accident and leave room for the hoses
to flex and move a bit without being ripped off.

I'm also reminded of a statistic that Bob Knockoll's has mentioned. It
seems that there is seldom a post impact fire in light aircraft if the
battery is ejected by the impact. Battery ejection might be a tricky
design objective but it does seem wise to try and keep fuel away from
the electrics which are probably the most likely ignition source.

Happy New Year to all...
Ken


Bob Patterson wrote:

To each his own .... I've always disliked header tanks, ever
since I lost a good friend who was burned in a Super Cub crash
because the header tank split & sprayed gas all over him & the
burning engine ...

I know you did a lot of work to crash-proof yours, and I think
it's mounted in back, instead of on the firewall like the Cub,
but to me it's still extra work, & an added hazard, and besides,
I'm all in favour of "active fuel management" ;-) --- often
the lack of attention to the fuel status is what causes a lot
of silence, and an instant glider, at inconvenient times ! ;-) :-)

"Returnless EFI" - now THAT sounds like the ideal answer !!
It would be great if Subaru went that way !

......bobp

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