Message-ID: <033a01be7d21$2eb61430$06b8b6c6@gjpc>
Reply-To: "Gerard J. Cerchio" <gjpc@circlesoft.com>
From: "Gerard J. Cerchio" <gjpc@circlesoft.com>
To: <lancair.list@olsusa.com>
Subject: Header Fuel Tank
Date: Fri, 2 Apr 1999 07:55:03 -0800
Mime-Version: 1.0

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Here is my two cents on fuel tanks.  I have a header
and wings out to the tips.  The header helps with the 
CG and is also allows for positve pressure on the 
inlet to the boost pump.  

I have transfer pumps in the wing roots that have
momentary contact down toggle switches to feed 
the  header.  The middle position is the off position.
The up position is AUTO.  I have a circuit that turns
the AUTO pumps on when ever the header is just
under 3/4 and fills it to 7/8.  I have indicators for
Left xfr pump on, Right xfr pump on, header high
and header low. I might add auto for the xfr pumps.

I also have a four way valve in the seat back just
in case this miracle of automation goes down. The
valve lets me select off, left, right and header. The 
plumbing was simple, most of it is under the passenger
seat it is all 3/8'.

Fuel management for me is turn the light wing's
AUTO switch to off for a little while.  Other than that
I just keep an eye on total fuel flow and fuel remaining.
If this gets too onerous I may have the auto circuit
try to keep the levels in the wings balanced by having
it deselect the light wing.  But without experience with
the setup it is hard to say how well it work in practice.

I think I may have put the battery in the header's 
place if I began that part of the project less then 7 
years ago but there seem to be a lot people flying
header tanks with no problems.  Also there is no
way to tie to the wings together or easily automate
wing tank switching.  I just like not having another
ongoing task in the cockpit.

Marv, why are you plumping a return on the IO
engine?  That seem to be really complicated.

Gerard

[Thanks for the input, Gerard.  All I know is there is supposed to be
a return line from the fuel pressure regulator.  Prior to Bill's comment
about plumbing it back to the input side of the high pressure pumps
my 20/20 tunnel vision had me thinking that it had to come back into the
cockpit.  (Perhaps that's the reason I suffer from this flat forehead <g>)

This is being a truly fascinating discussion, as it always amazes me how
many different ways there are to approach any system.  If any of you
care to share a sketch of your fuel system, or at least send along a 
brief description, I'd be pleased to gather all the info together into
a separate section for the LML homepage so others can see some of these
other possibilities long after this discussion has ground to a halt.

    <Marv>  ]