----- Original Message ----
From: Bill & Sue <5zq@cox.net>
To: lml@lancaironline.net
Sent: Saturday, March 22, 2008 8:40:12 PM
Subject: [LML] header tank

Good Morning Steve,

I'll give you my opinion but I must warn you it's quite biased. I'm a BIG
proponent of header tanks. So much so that I'm building one into the IV that
we're building now. So here it is:

    PUT IN THE HEADER TANK

If you take a look at accident statistics in Lancairs, the majority are
pilot error. If we narrow the list down to airframe problems, fuel related
ones are at or near the top of the list. The header tank system is beautiful
in its simplicity.  It's gravity feed, you don't need to suck fuel UP to the
engine and you can burn both wings together. This feature alone eliminates
big potential problems; pump cavitation and unporting the fuel pickup to
name a few. You can forget the slosh doors.

A big practical as well as safety benefit is range. In many instances, range
is safety. In all instances, range is comfort. I really like flying our 320
from Florida to Virginia knowing that if the weather is crappy in Virginia,
I've got fuel to fly comfortably to an alternate...like Chicago, Montreal or
Boston...really! The header tank will give you another 10 or 11 gallons.
HOWEVER lets assume that the header tank gave you NO more fuel capacity.
Even then it would increase your practical range. Here's my reasoning;

No header tank. You've got two very long, very flat fuel tanks. The fuel
quantity in a tank of this shape is difficult to measure accurately.
Besides,  you really don't want to get the tanks very low for fear of
unporting the pickups. Generally in this situation I'd be getting pretty
nervous when the gauge, or the clock, said that I was getting anywhere close
to 1/4 tank. So in a 50 gallon system I'd want to be on the ground (in good
VFR weather) with no less than 13 gallons...probably more.

Header tank. You've got the same wing tanks but now these are just aux tanks
feeding the main tank, the header. The header is a narrow, short (compared
to the wings) and HIGH tank. This shape of tank makes it easy to measure the
fuel quantity with a high degree of accuracy. The sight gauge is practically
failure proof. We've got a sight gauge and a capacitance gauge that always
agree. If the gauges say that I've got 5 gallons, then I've got 5 gallons.
Running the wings dry is absolutely NO problem. Once the wings are empty you
KNOW that you still have 90 minutes or more in the header. Because of the
MUCH greater certainty of useable quantity in the header, I am very
comfortable flying down to 5 gallons or so.  I KNOW that I can make 5
gallons last 45 minutes and I KNOW that I, in fact, DO actually have 5
useable gallons. Same 50 gallons but now I've got at least 8 more gallons
that I'm comfortable using. That's 200 miles!

There's an old saying among the Bonanza guys that the most effective SPEED
mod that you can do to that plane is to add tip tanks. It doesn't give you
more knots, but it eliminates the fuel stop and THAT makes if faster from A
to B if you're going a long way.

If I've convinced you to build the header tank, then here are some
additional recommendations.

Make it removable. Much easier for maintenance. (the standard Lancair header
can easily be made removable)

Put in a wing tank cross feed. This is easy. Essentially what we have in our
plane is a 3/8 tube running along the floor from one wing tank to the other
wing tank. In the middle (right under the console) I've got a ball valve.
The ball valve has an extended shaft connected to a knob on the console.
Open it and the fuel can gravity flow freely from one tank to the other.
Close it and you've got two separate tank systems. On either side of the
crossfeed valve I've got "T's" that connect to the respective fuel transfer
pumps. With the crossfeed valve open, EITHER pump can pump all of the fuel
from BOTH wings since it will gravity flow to the low point in the system
(the crossfeed valve).  A single transfer pump failure still allows you to
access ALL of your fuel. Without a crossfeed, you not only limit your
available fuel but you've just turned the failed side fuel into ballast. You
might not even be able to use all of the good side fuel because of the
unbalance problem.

Put in an automatic fuel transfer system. A couple of float switches in the
header and a simple circuit will allow you to put the pumps to "auto" and
they will keep your header between full and 8 or 9 gallons with no action
from you. The system should also have a "manual" capability where you can
turn the pumps on or off as you wish.

Baffle the float switches. We've got our float switches in a rather small
sub compartment of the header with smallish holes to allow fuel in or out.
This makes sloshing or turbulence less likely to affect the operation of the
auto system. (the sight gauge taps off the same area)

Add a third float switch (or Pillar Point sensor) in the header at the 4 or
5 gallon level. This operates your LOW FUEL light (the big red one) in case
your automatic system fails and you don't notice, or in case you need a
reminder to land NOW.

*Optional... We also put float switches at the bottom of the wing tanks that
are connected through the pump circuit to a "wing low" light. If the wing is
empty (or close) AND you've got a pump on, you'll get the light. This keeps
you from operating the transfer pumps dry for extended periods as well as
giving you notice that you've emptied your wing.

I've attached  pictures that I hope will make some of this clear. Please
feel free to call or write (or visit) if I can help further. I'll be in
Milan, TN on the 1st. Are you near there?

Bill Harrelson
N5ZQ 320 1,450 hrs
N6ZQ  IV under construction

5zq@cox.net
(540) 372-8738





> I'm working on my wings and am getting sorta close to closing them.  This
> is my first homebuilt (big tail outback gear 360 I bought  partially
> completed).  The guy I bought from and a couple of other  Lancair
> builder/owners here in Memphis had me convinced that I did not  need a
> header tank and should do the slosh bay/doors.  Thing is, I do  not like
> the piano hinge slosh door arrangement.  It's kinda cheesy  and I'm not
> convinced it'll remain loose and floppy.  they seem to  want to bind which
> could be disastrous.  I've been hunting around on  the net for a valve or
> something I could put in the slosh rib -  something I would feel is much
> more reliable.  As part of my research  tonight , I started reading posts
> and now I've about convinced myself  I should have a header tank.  I have
> chosen to use a Mazda rotary to  power my airplane so I'm probably already
> battling an aft CG.  Avionics available in 2008 are pretty small so I
> think I've got plenty  of room. I've even got a Lancair header tank from
> someone else's 360  (mine was missing )  but I think I'd make one that's
> removable.  I  remember reading one of your post where you'd mentioned a
> cross feed  valve so I was wondering if you'd send me whatever diagrams
> you have.  I'd also really like to hear your thoughts on this whole
> header  business,  If I decide to go header, can I skip the slosh bay
> nonsense?
>
> Thanks,
>
> Steve