On Mon, 18 Apr 2005 23:56:18 -0500, "Highflyer" wrote:


"Matt Barrow" wrote in message
...

http://www.avweb.com/news/columns/182044-1.html
August 9, 1998

Pelican's Perch #7:
Run That Fuel Tank Dry!

AVweb's John Deakin takes aim at yet another OWT (Old Wive's Tale). While
running a fuel tank dry in your recip powered plane may serve to increase
your heart rate, John explains why it's not such a bad thing at all, and
it
is probably a really good idea for most of us. In fact, John explains why
it's one of the first things you ought to do with a new plane and how it
could save your life someday.


Back in the days when I learned to fly it was common practice to run each
tank dry in turn. That way you knew precisely where ALL of your remaining
fuel was located.

Many aircraft had fuel return lines from the engine to allow excess fuel to
be relieved back to a tank. Most of these fuel return lines would actually
return several gallons per hour in normal cruise flight.

The Deb is piped up like this but it returns a lot more fuel than a
couple gallons.

It will empty two 10 gallon tanks in a bit over half an hour. It only
burns 13.5 to 14 GPH.

The tank switching sequence is different when the tip tanks are used.
They simply transfer to the adjacent main. Both mains have their own
return line, but the aux tanks return to the left main.

Mains are in front of the spar and CG, aux are to the rear of the spar
and CG, while the tips are on the CG.

4 tank sequence:
45 minutes on left main. Aux till dry or close to it. Now you have a
choice which mainly depends on how far out of balance you are willing
to go. I prefer to go 30 minute intervals starting with the left
tank. You are carrying 5 1/2 hours, no reserve. At 4, I'm looking for
a place to stop.

6 tank sequence:
First requires burning off enough to get the 15 gallons from each tip
into the main. The tips transfer to dry in roughly 45 minutes. You
do this by burning off a minimum from each main and then transferring
while using gas from the mains with the idea that the mains will be
full at the end of the transfer..

You basically end up with the mains and auxes full so then you can do
the 4 tank sequence.

It's a bit of an exercise and you can easily end up flying a bit
lopsided if you miscalculate:-))

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com
The early Cherokee Six that I flew charters in back in the sixties and
seventies had half a dozen tanks and a specific sequence to use them up if
you didn't want to either vent overflow or exceed the wing bending moments
due to improper distribution of weight between the fuselage and the wings!

The "Twin Bitch" that I flew in the fifties had fuel tanks all over the
place. Fuel management in many of these older airplanes is much more
complicated than the simple "ON-OFF" of the Cessna 150/2 family. :-)

Highflyer
Highflight Aviation Services
Pinckneyville Airport ( PJY )