Running dry?

BTW, Beech sez I've got 20 gallon tanks, with 17.5 usable. After running
my right tank dry, I can put fill with 20.8 gallons. [...]

Fortunately, what Beech put in my owners book were written by engineers
with an engineers fudge factor. [...] Way lotta slop there.

"Usable" means usable in EVERY flight attitude. The "unusable" fuel can
be used in SOME flight attitudes, obviously some of that unusable fuel
could be used in the specific flight attitude in which you were at the time.

Jose
--
Quantum Mechanics is like this: God =does= play dice with the universe,
except there's no God, and there's no dice. And maybe there's no universe.
for Email, make the obvious change in the address.

Mortimer Schnerd, RN wrote:

Now, to get back to the first question: how often does one run a tank dry
intentionally? If I was in a Cherokee Six with four tanks and had passengers,
hopefully never. The downside of this is that if you left just a couple of
estimated gallons in each tank, you have lost a significant amount of useful
fuel.

If I were trying to stretch a flight and even then only if I were alone, I might
consider running one dry. But I have to tell you: running a tank dry in a
Cherokee results in te longest 30 seconds of your life. I ran a C-210 tank dry
once and almost the second I hit the boost after switching the fuel selector I
got a restart. Not so in the Cherokee... it takes a while. A loooong while.
Kind of scarey.

I've run a C-6 main tank dry (unintentionally) and the engine sputtered
for about 3 seconds (the time it took me to turn on the aux pump and
switch to the other main tank). My fuel management method in the C-6 is:

Left Main: 1 hour
Right Main: 1.5 hours
Left Main: 30 minutes
Right Aux: 45 minutes
Left Aux: 45 minutes
(left and right may be swapped as I have no hard and fast rule for which
tank I start on)

This gives me 4.5 hours and leaves me with about 10 minutes in each main
and 25 minutes in each aux tank, which is about as close to empty as I
want to come. In practice, I usually only use the second aux tank for
my approach and landing because I don't care to sit for longer than 4
hours at a stretch. In the case of running the tank dry, I was getting
ready to switch to the first aux tank when the tank ran dry (less than a
minute left on the timer), so I was ready for it and the engine didn't
have the chance to fully shut down, but it was enough to wake up my wife
in a panic. (-:


-m
--
## Mark T. Dame
## VP, Product Development
## MFM Software, Inc. (http://www.mfm.com/)
"I used up all my sick days, so I'm calling in dead."

In rec.aviation.piloting Jose wrote:
main an run it dry. You are left with an hour's worth of fuel in the
left main and no longer have to switch tanks for the duration of the
flight.

Unless the fuel return didn't function properly (can you preflight it?),
in which case you have zip.

Owning one of these planes that Oval mentioned (pressure carbed E-225
powered Bonanza), I doubt you could even get it started if the fuel return
wasn't working. It's sort of like asking if you can start the plane
without the magnetos.

--
Frank Stutzman
Bonanza N494B "Hula Girl"
Hood River, OR

In rec.aviation.piloting Jose wrote:
BTW, Beech sez I've got 20 gallon tanks, with 17.5 usable. After running
my right tank dry, I can put fill with 20.8 gallons. [...]

Fortunately, what Beech put in my owners book were written by engineers
with an engineers fudge factor. [...] Way lotta slop there.

"Usable" means usable in EVERY flight attitude. The "unusable" fuel can
be used in SOME flight attitudes, obviously some of that unusable fuel
could be used in the specific flight attitude in which you were at the time.

True, but so what?

Did you notice I was putting 20.8 gallons in what is supposed to be a 20
gallon tank? My point is that POH are not completely accurate in regards
to fuel managment, and that you don't know how inaccurate they are for
YOUR particular plane until you run a tank dry.


--
Frank Stutzman
Bonanza N494B "Hula Girl"
Hood River, OR

Recently, Greg Copeland posted:

On Thu, 18 Aug 2005 17:21:16 +0000, Neil Gould wrote:
Besides being pointless? How about being uneccesarily risky?


[...]
So what risk factor can you assign to what is more or less, a
non-event?

It's a non-event *if* the tank runs dry at a convenient time and place,
*if* the engine restarts (I've had one heck of a time restarting a warm
fuel-injected engine at times), etc. Even if these risks are low, they're
still uneccesary, so I'll stand by my opinion. ;-)

As for the "why", John Says, "I'd like to take a look at fuel
management, and since my method sometimes calls for running a tank
dry, let's get that out of the way first." In other words, its his
strategy for fuel management which lets him known and understand how
much he really has in reserve and how much can he get out of the
"unuseable". Should he have an event where he has to bite into his
reserves, he never has to say, "I sure hope I have enough. I wonder
how much is there".

What's the point in all of this? If he can't figure out fuel consumption
rates from the amount of fuel that he replaces after the flight, what good
is running the tanks dry? One is supposed to have a 45-minute reserve VFR;
that's quite a bit more fuel than running dry. The whole idea is *not* to
run dry. To me, it sounds like a fools game to do otherwise.

Neil

Greg Copeland wrote:

How many run their tank(s) dry as part of their fuel
management strategy? If you don't run dry, why not? Aside from the heat
beat skipping which is sure to follow the first couple of times, what's
the down side to this strategy?

I do not. The examiner for my PPC recommended a variation of this -- he said to
switch tanks every half an hour. He said "When the tank you're on runs dry,
you'll know exactly how much is left in the other tank." Well, I wasn't going to
argue with him, but what if it runs dry two minutes after you switched? You'd
better be on final approach.

As for the down side to this strategy, that's what killed Will Rogers and Willie
Post. Willie used to fly on one tank until it ran dry and then switch to the
next. The tank he was on ran dry a few hundred feet up on takeoff.

George Patterson
Give a person a fish and you feed him for a day; teach a person to
use the Internet and he won't bother you for weeks.

On Thu, 18 Aug 2005 19:02:46 +0000, Neil Gould wrote:

Recently, Greg Copeland posted:

On Thu, 18 Aug 2005 17:21:16 +0000, Neil Gould wrote:
Besides being pointless? How about being uneccesarily risky?


[...]
So what risk factor can you assign to what is more or less, a
non-event?

It's a non-event *if* the tank runs dry at a convenient time and place,
*if* the engine restarts (I've had one heck of a time restarting a warm
fuel-injected engine at times), etc. Even if these risks are low, they're
still uneccesary, so I'll stand by my opinion. ;-)


At a convenient time? That's the difference between running out of fuel
and running the tank dry. After all, if you chosen to run the tank dry,
it better be because its both a convenient time and place. If you allowed
your self to run out of fuel at an "inconvenient time and place", then you
ran out fuel, which is not what is advocated here. Remember, this is
part of a fuel management strategy and not blindly flying until the tank
reads empty and the engine sputters.

Deakin's article clearly spells out that there are some planes which
this should not be done on. Fuel injected engines is probably one such
category to not try this on because of vapor-lock issues. In most
carborated engines, in most planes, I must admit it sure sounds like a
non-event to me. Again, as even Deakin points out, there are exceptions
to every rule; whereby he even provides one.

Also, I do thank you for sharing your opinion.

As for the "why", John Says, "I'd like to take a look at fuel
management, and since my method sometimes calls for running a tank
dry, let's get that out of the way first." In other words, its his
strategy for fuel management which lets him known and understand how
much he really has in reserve and how much can he get out of the
"unuseable". Should he have an event where he has to bite into his
reserves, he never has to say, "I sure hope I have enough. I wonder
how much is there".

What's the point in all of this? If he can't figure out fuel consumption
rates from the amount of fuel that he replaces after the flight, what good
is running the tanks dry? One is supposed to have a 45-minute reserve VFR;
that's quite a bit more fuel than running dry. The whole idea is *not* to
run dry. To me, it sounds like a fools game to do otherwise.

Fair enough.


Neil

Greg

On Thu, 18 Aug 2005 19:25:45 +0000, George Patterson wrote:

Greg Copeland wrote:

How many run their tank(s) dry as part of their fuel management
strategy? If you don't run dry, why not? Aside from the heat beat
skipping which is sure to follow the first couple of times, what's the
down side to this strategy?

I do not. The examiner for my PPC recommended a variation of this -- he
said to switch tanks every half an hour. He said "When the tank you're
on runs dry, you'll know exactly how much is left in the other tank."
Well, I wasn't going to argue with him, but what if it runs dry two
minutes after you switched? You'd better be on final approach.

Doesn't sound like that's a winning strategy for night VFR either. Seems
like a 45-minute to an hour switch would be better.


As for the down side to this strategy, that's what killed Will Rogers
and Willie Post. Willie used to fly on one tank until it ran dry and
then switch to the next. The tank he was on ran dry a few hundred feet
up on takeoff.


On take off? Doesn't that mean the PIC failed to properly fuel the plane
rather than invalidate the strategy? How was that not pilot error, pure
and simple?


George Patterson

Greg

I remember reading that article several months ago, so I just breezed
through it this time. A couple points that I've thought about, along with
the author. I've never ran a tank dry, and don't intend to. Why not?
Well, even disregarding the potential safety issues, we have fuel injected
engines and our electric fuel pumps have great big red stickers on them that
say DO NOT RUN DRY. $632 each for rebuilt models, I think I won't gamble
that kind of cash.

I haven't done it yet, but I would like to examine, with a mirror as Denny
has, our rubber fuel bladders. I would also like to know their exact
current capacity. I would like to assure myself that they are still
"buttoned" down and have not even partially collapsed. To date, I've fueled
each of our 36 gallon tanks, with 30 gallons each, 6 gallons remaining in
each, about 2 of which was unusable according to the book. So I'm fairly
confident that they hold at least 30 gallons each.

But rather than running a tank dry, what's wrong with simply running it low,
then draining the remainder through the sump? This is "supposed" to be the
lowest point on the tank or in the system, right? It would seem that any
"crud" that hasn't been sucked through the fuel filter, would then just
dribble out into your gas can.

Afterwards, the bladders can be inspected and filled to the brim for an
accurate capacity. All done on the ground.

Jim

"Usable" means usable in EVERY flight attitude. The "unusable" fuel can
be used in SOME flight attitudes, obviously some of that unusable fuel
could be used in the specific flight attitude in which you were at the time.


True, but so what?

Did you notice I was putting 20.8 gallons in what is supposed to be a 20
gallon tank? My point is that POH are not completely accurate in regards
to fuel managment, and that you don't know how inaccurate they are for
YOUR particular plane until you run a tank dry.

So there are different values of "dry". When you run a tank "dry" that
doesn't mean there's no gas in it. The problem isn't that the POH isn't
accurate (and I make no statements about its accuracy), but rather, that
"empty" isn't a yes or no thing.

The fuel has to be able to flow until you reach the "unusable fuel".
After that, the fuel =might= flow in certain attitudes (and almost
certainly will, to some extent, in some of them). So, if you are trying
to measure "usable fuel" this way, you've run the tank =more=than= dry
when the engine quits, but you don't know how much more than dry you've
run it, because that depends on the flight attitude when you did that.

And if you're trying to measure =total= fuel, running a tank dry doesn't
mean it has no fuel in it.

Jose
--
Quantum Mechanics is like this: God =does= play dice with the universe,
except there's no God, and there's no dice. And maybe there's no universe.
for Email, make the obvious change in the address.