Message-ID: <005401be7c10$74a8e7e0$28c295cf@bill>
From: "William T Bartlett" <wtbart@olympus.net>
To: <lancair.list@olsusa.com>
Subject: LNC2 Fuel system plumbing
Date: Wed, 31 Mar 1999 23:22:16 -0800
Mime-Version: 1.0

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I can't see why any one would want to pump from wing tank to the header tank
(except that the manual says to) and many builders didn't even put a
header tank in. Reasons not to do so.. makes fuel management hard, great
chance of pumping fuel overboard. Loss of electrics can result in lots
of unusable fuel. All in all feeding the engine out of the header only
requires very heads up fuel management.

The new English four port (header, R, L, off) valve is a beauty (I have
one of the old style cheap ones) and if mounted just forward of the main
spar, against the belly skin, it is at a low point in the system. Mount
the boost pump forward of the 4 port valve, under the passenger floor
board (inverted keeps the lines lowest). My wing tanks will feed the
gascolator with the boost pump off (not much pressure, but there isn't
much head from the header tank either). I take off on the
header then
30 min on each wing tank till empty. When the wing tanks are dry I know I
have 11.9 gals in the header and can see it in the sight gage. I have an
extension to the top of my console for the valve handle.

Colebrook has a well thought out system to feed out of both wings at once
without unporting, but it does require lots of extra building and
parts.

Bill N7WB

[Thanks for the comments, Bill.  I wasn't going to use a header tank
but when I thought about the potential plumbing nightmare which would 
ensue to provide a return from the fuel pressure regulator (engine will
be fuel injected) to the active tank, I figured the header was the
easiest way to go.  As I'm planning an all electric panel there will be
2 batteries in case of an alternator failure, so I'm not real concerned
about an all out power failure.  I'm trying to design all of the systems
according to the Bob Nuckolls philosophy, that being that any single sub-
system failure can not be considered catastrophic.  With enough redundancy
and proper planning I think I can achieve that goal.

I was looking at the schematics for Simon Creasy's aircraft and liked the
KISS system which he incorporated to keep the header tank full... provide
a float switch which controls the power to both transfer pumps at once.
If one transfer pump moves more fuel than the other requiring some
intervention, switch from AUTO to MANUAL mode to pump from the fuller tank.
A valved crossover would eliminate the failure mode of one transfer pump
giving up the ghost.

I agree that your system is undoubtedly an excellent one for a carbureted
engine, but have considerable misgivings about making it work with the
requirements imposed by the fuel injection system.   <Marv> ]