Fuel tank balance

"Steve Foley" wrote in message
...
"Mxsmanic" wrote in message
...

That's what puzzles me: If you're not supposed to have a significant
difference between the two, why aren't the two tanks just connected so
that they always drain at the same rate on both sides?

On a low wing airplane, you need a fuel pump to get the fuel to the engine.
If you have one fuel pump connected to both tanks, and one tank runs dry,
the fuel pump will be sucking only air, and no fuel from the other tank.

If you put in two fuel pumps, and one tank runs dry, you will probably burn
out the fuel pump running it dry.

If you put in a way for the pump to shut down when it's dry, you run the
risk of a faulire that shuts down the pump when there is still fuel in the
tank.

The goal is relable and simple. One fuel pump (actually, mine has an engine
driven pump and an electric backup pump), and a valve to select tanks.


Why would you
_want_ one wing substantially heavier than the other?

When I fly alone, the left side of the plane is heavier. If I burn fuel
from
the left tank, after about an hour the plane is more balanced.

Mxsmanic wrote:
why aren't the two tanks just connected so
that they always drain at the same rate on both sides?

Also keep in mind the need to isolate a fuel leak.

Steve,

when the
minute hand


What'S that? ;-)

Otherwise, nice trick.

--
Thomas Borchert (EDDH)

"Thomas Borchert" wrote in message
...
Steve,

when the
minute hand


What'S that? ;-)




That's the thing I forget to wind prior to each flight g

"Mxsmanic" wrote in message
...
Marty Shapiro writes:

Not too noticeable until about 8,000'. Then it gets noticeable. Above
11,000' it gets very, very noticeable. Go to Pike's Peak and see what
happens!

Yesterday I tried flying a Piper J-3 and a Cessna 172 over the top of
(I think) Mount Rainier (the tall mountain near KSEA), and they both
seemed to struggle as we approached the altitude of the peak. I
turned around and went back when it became obvious that I wasn't going
to make it. Not sure if it was engine power that lacked, or just air
density that was too low, or what. I was flying for fun and did not
check the altimeter.

--
Transpose mxsmanic and gmail to reach me by e-mail.

Yes, It is Mt. Rainier... It looked beautiful yesterday, even with the haze
that goes up to 2000', and could see it from Skagit Regional/Bayview (KBVS).
Went up there for lunch.

Reason you can't go over the top of Rainier in a 172 is the Service Ceiling
of a 172 is about 14,000 (some models are lower, some are slightly higher).,
the top of Mt. Rainier is 14,410 ft. I imagine the service ceiling for a
J-3 Cub would be lower than that of a 172.

Service Ceiling I believe is defined as "where Vx equals Vy", which where
they meet will result in a minimal to non-existent climb rate. Vx increases
as altitude increases, Vy decreases as altitude increases. Also as you
climb less dense air produces less lift (get to a point where there is not
longer "surplus" lift to produce a climb), and less engine power to move the
aircraft through the air. To climb a 172 to that altitude takes a long
time... :-) which is because as you climb the wings produce less and less
lift and the climb rate decreases, along with the engine not being able to
produce as much power. Yesterday, I flew up to KBVS from KRNT at 4500',
which I didn't reach until I was almost over KPAE, but then I had to hang
out at 2500' for a bit waiting for the Center Controller to get me a squawk
code and clear me through the Class B. :-) Coming home, I was telling my
passenger..."The question for the trip home is 5500' or 3500'?" And she
asked "Why?" I explained the VFR Altitude Rule, and then said "It takes a
'long time' to get to 5500' and then by the time you get there you pretty
much have to start descending, as it is easier to avoid the Class B."
Picked 3500' for the trip home, as that is sufficient to clear the Class D
at KPAE (Class D at KPAE goes to 3100') Route was basically
KRNT-KPAE-KBVS, KBVS-KPAE-KRNT

-Wade Hasbrouck
PP-ASEL
http://spaces.live.com/wadehas

Mxsmanic wrote in
:

Marty Shapiro writes:

Not too noticeable until about 8,000'. Then it gets noticeable. Above
11,000' it gets very, very noticeable. Go to Pike's Peak and see what
happens!

Yesterday I tried flying a Piper J-3 and a Cessna 172 over the top of
(I think) Mount Rainier (the tall mountain near KSEA), and they both
seemed to struggle as we approached the altitude of the peak. I
turned around and went back when it became obvious that I wasn't going
to make it. Not sure if it was engine power that lacked, or just air
density that was too low, or what. I was flying for fun and did not
check the altimeter.


I was talking about modern automobiles with fuel injected engines and
electronic ingnition sensors which automatically adjust the fuel/air
mixture to compensate for altitude.

Mt. Rainier peak is 14,410' MSL, which, IIRC, is about 300' above the
service ceiling of a C-172N, but about 1,500' below the absolute ceiling.
Wikipedia states the Piper J-3 service ceiling is 11,500' MSL.

--
Marty Shapiro
Silicon Rallye Inc.

(remove SPAMNOT to email me)

"Mxsmanic" wrote in message
...
Robert M. Gary writes:

Set power using throttle to the appropriate setting on your manifold
pressure. If you fly around full throttle down low you'll over stress
your engine. At cruise you usually leave the throttle full forward
(unless you have turbo charged).

How do I know when the engine is potentially being stressed based on
the instruments? Low manifold pressure?

You can't set the propeller pitch but you can adjust the propeller RPM.

On the A36 and B58 I've been trying to fly, there's a lever that says
pitch next to the throttle, and it has a feather setting (which I have
never used), so I presume it's pitch of the propeller blades.

Dumping extra fuel into the cylinders is good when climbing but not so
good during cruise. In cruise we lean the plane out for a more optimal
mixture.

Is that just for reasons of economy, or does a rich mixture damage
something in the engine?

Rich Mixture will not typically damage the engine... however running an
engine too lean can, because if you lean too much the cylinder head
temperatures will be higher than normal and can cause detonation. Running
too rich can cause the plugs to foul. Also if you don't lean as you climb,
you will lose power because the engine is running to rich.


You car does the same. For the same RPM your car will set a
higher mixture during acceleration vs. in freeway driving. Most planes
have a EGT (exhaust temp ) to measure mixture, but you can do it just
by sound in a more basic plane.

Higher EGT = rich mixture?

No... Higher EGT indicates leaner mixture. Excess fuel in the cylinder has
a cooling effect. Leaning procedure in many planes is to lean to peak EGT
and then richen to 25 - 50 degrees of peak EGT, if there is an EGT guage.
Plane I flew yesterday, does not have an EGT... So you lean for Max RPM and
then richen slightly for smooth operation, and this was for a 1976 Cessna
172M.


Planes don't do this all at once for the same reason I have to shift my
car, because they don't use an automatic system. There are such systems
out there for planes but they are very expensive since it would be very
bad if it didn't work correctly.

Understood. My main concern is whether or not I'll get into trouble
if I fail to do all the tweaking of engine parameters while flying.


Depends on your definition of "trouble"... Running an engine full rich at
7000' and then trying to climb at a certain rate to clear an obstacle... You
may not have the power you need to climb and clear the obstacle, and think
that could qualify as "trouble"

--
Transpose mxsmanic and gmail to reach me by e-mail.

-Wade Hasbrouck
PP-ASEL
http://spaces.live.com/wadehas

"B A R R Y" wrote in message
...
On Sun, 24 Sep 2006 10:18:34 -0700, "Wade Hasbrouck"
wrote:

Service Ceiling I believe is defined as "where Vx equals Vy", which where
they meet will result in a minimal to non-existent climb rate. Vx
increases
as altitude increases, Vy decreases as altitude increases

I always thought it was where the plane was no longer capable of
climbing at a rate greater than 100 ft/min.


You are correct... I should look at Wikipedia before typing... :-)

"From Wikipedia, the free encyclopedia

In aeronautics, the service ceiling is the density altitude where the flying
in a clean configuration, at the best rate of climb airspeed for that
altitude, and with all engines operating and producing maximum continuous
power will produce a 100 feet per minute climb. Margin to stall at service
ceiling is 1.5g."

Will have to go back to the reference book that talked about the point where
Vx and Vy are equal and see what they called that... :-)

Wade,

however running an
engine too lean can, because if you lean too much the cylinder head
temperatures will be higher than normal and can cause detonation.

...

No... Higher EGT indicates leaner mixture. Excess fuel in the cylinder has
a cooling effect.

Sorry, but you're wrong. Running not lean enough can cause detonation. Or,
more exactly: Putting the mixture in the wrong place can. Cylinder pressures
are highest at about 50 to 75 rich of peak. Higher EGT does indicate closeness
to peak EGT, but not a leaner mixture. The leaner the mixture, the cooler the
EGT - once you're beyond peak.

The misconceptions behind your statements lead to people not liking to
contemplate LOP operations, which is why I point them out.


--
Thomas Borchert (EDDH)

On 09/24/06 11:13, Wade Hasbrouck wrote:
"B A R R Y" wrote in message
...
On Sun, 24 Sep 2006 10:18:34 -0700, "Wade Hasbrouck"
wrote:

Service Ceiling I believe is defined as "where Vx equals Vy", which where
they meet will result in a minimal to non-existent climb rate. Vx
increases
as altitude increases, Vy decreases as altitude increases

I always thought it was where the plane was no longer capable of
climbing at a rate greater than 100 ft/min.


You are correct... I should look at Wikipedia before typing... :-)

"From Wikipedia, the free encyclopedia

In aeronautics, the service ceiling is the density altitude where the flying
in a clean configuration, at the best rate of climb airspeed for that
altitude, and with all engines operating and producing maximum continuous
power will produce a 100 feet per minute climb. Margin to stall at service
ceiling is 1.5g."

Will have to go back to the reference book that talked about the point where
Vx and Vy are equal and see what they called that... :-)


It the airplane's absolute ceiling.


--
Mark Hansen, PP-ASEL, Instrument Airplane
Cal Aggie Flying Farmers
Sacramento, CA