Fuel transfer pump

I want to add an aux tank & transfer fuel to main tank with a pump
during flight. I think it makes fuel management easier if the pump
transfer close to the engine's burn rate, say 14 gph.

I also want the pump to pick up fuel from the top of the aux tank via
a tube to the bottom of the tank so no hole below fuel level is
necessary. Does that mean I need a "self-priming" pump?

What kind of pump should I get?
Name & model no.?

Oh, it should run on 12V.

Many thanks,

Robin

"rmhou at yahoo.com" wrote in message
ups.com...
I want to add an aux tank & transfer fuel to main tank with a pump
during flight. I think it makes fuel management easier if the pump
transfer close to the engine's burn rate, say 14 gph.

Here's a recommendation for wiring. Use a timer switch as is used for
bathroom fans. It has several advantages:
1. It is not likely to be confused with any other switch.
2. You can set it for an interval which will never overfill your main tank
from the aux.
3. You can't forget to turn it off.
4. Your electric pump can transfer fuel faster than, say 14 gph, without a
problem.

Rich S.

"Rich S." wrote

Here's a recommendation for wiring. Use a timer switch as is used for
bathroom fans. It has several advantages:
1. It is not likely to be confused with any other switch.
2. You can set it for an interval which will never overfill your main tank
from the aux.
3. You can't forget to turn it off.
4. Your electric pump can transfer fuel faster than, say 14 gph, without a
problem.

I like the idea. I would want to see an over-ride, as a backup.

Bathroom fan switches are "not quite" up to aerospace quality standards.

How is this one, too?

Put the transfer pump running off of a relay, that is hooked to a "full
tank" sensor. Even if you used a timer, like above, it would prevent an
over flow situation - if you set the timer for too long, too soon.
--
Jim in NC

"rmhou at yahoo.com" wrote in message
ups.com...
I want to add an aux tank & transfer fuel to main tank with a pump
during flight. I think it makes fuel management easier if the pump
transfer close to the engine's burn rate, say 14 gph.

I also want the pump to pick up fuel from the top of the aux tank via
a tube to the bottom of the tank so no hole below fuel level is
necessary. Does that mean I need a "self-priming" pump?

What kind of pump should I get?
Name & model no.?

Oh, it should run on 12V.

Many thanks,

Robin

There is a certain amount of strategy in both designing and using auxilliary
fuel systems.

Also, I am confident that nearly everything that actually works, and a lot
of things that are problematic, are already well known. If you are only
tankering fuel due to a price differential, it is not too big a deal; but if
you actually need the fuel, then you need some real advice with some real
experience to back it up. I have also heard/read that you operated the
aircraft differently for that kind of flying.

With that in mind, I would strongly recommend that you ask around your local
airport(s) and talk to ferry pilots as well as to mechanics in whom they
express confidence.

Peter
Just my $0.02

"Morgans" wrote in message
...

Bathroom fan switches are "not quite" up to aerospace quality standards.

Used the way it should be, failure of the switch shouldn't be a factor.

Put the transfer pump running off of a relay, that is hooked to a "full
tank" sensor. Even if you used a timer, like above, it would prevent an
over flow situation - if you set the timer for too long, too soon.

What was that quote about idiots and failures? I can't remember right now
but one cannot idiot-proof everything. I think adding a "full tank" sensor
would be overkill. The setup in the Emeraude I had (which went in killing
the pilot because of completely empty tanks) had a 20 gallon main and a 5
gallon aux tank. When the main got down to half, one would crank the "fan
switch" over to it's stop and it would dump the five gallons into the main
and then shut off, saving the pump and battery for the next time.

A simple setup and one designed to save the pilot's brains from overload so
he can deal with the lowering overcast he just flew into.



Rich S.

"Morgans" wrote in message
...

Bathroom fan switches are "not quite" up to aerospace quality standards.

Have you ever had a bathroom fan switch failure? That's got to be ugly.

Rich (where's the match? hack,hack) S.

rmhou at yahoo.com wrote:
I want to add an aux tank & transfer fuel to main tank with a pump
during flight. I think it makes fuel management easier if the pump
transfer close to the engine's burn rate, say 14 gph.

I also want the pump to pick up fuel from the top of the aux tank via
a tube to the bottom of the tank so no hole below fuel level is
necessary. Does that mean I need a "self-priming" pump?

What kind of pump should I get?
Name & model no.?

Oh, it should run on 12V.

Many thanks,

Robin


Dont make this more complicated than it has to be.

Fuel pumps work best when they are not SUCKING, but are already primed
and PUSH the fuel to its destination. Cars do this best with submerged
fuel pumps in the fuel tank. Next best is a pump below the low point of
the tank, with a gravity prime. This is more common with small GA
aircraft than the submerged pump approach. Think carefully before
setting up a situation that requires siphoning fuel with a suction. This
is a recipe for vapor lock.

As for fuel management, you may find a pump with your flow rate. You can
find stuff at automotive sites - Summit Racing, perhaps, but do the
job right with AN fittings and rubber-free hoses - teflon lined, etc.

What is possibly "easier" is to use a stopwatch and know the flow rate
of your tank. Having a timer on the tank pump can make this even less of
a hassle, and you can make it transfer, say... 10 gallons with every
button press (over time, of course)

Dave

Rich S. wrote:
snip

What was that quote about idiots and failures? I can't remember right now
but one cannot idiot-proof everything.

Probably a variation of "when someone invents an idiot proof device
someone else will invent a better idiot.

Dan, U.S. Air Force, retired

rmhou at yahoo.com wrote:
I want to add an aux tank & transfer fuel to main tank with a pump
during flight. I think it makes fuel management easier if the pump
transfer close to the engine's burn rate, say 14 gph.

I also want the pump to pick up fuel from the top of the aux tank via
a tube to the bottom of the tank so no hole below fuel level is
necessary. Does that mean I need a "self-priming" pump?

What kind of pump should I get?
Name & model no.?

Oh, it should run on 12V.

Many thanks,

Robin

To directly address your question:

To achieve your goal, use a garden-variety Facet low pressure pump made
for carb engines. I'd probably order from Van's since I'm building an RV-7.

http://www.vansaircraft.com/cgi-bin/...duct=pump-carb

or go to vansaircraft.com & search for 'fuel pump'.

Install a restricter in the line from the pump to the main tank; size
the orifice by experiment to get the flow you desire. The pump won't
care about the restriction. Evidence: there are quite a few H-series
320's flying on low wing homebuilts with only 2 facet electric pumps
(orimary & backup) to supply fuel to the carb. If you mount the pump low
in the fuselage & reasonably close to the aux tank, it will self prime
just fine unless you're talking about a tank that's several feet tall.
(Seldom noticed fact: every 2 seat RV I've ever seen has the fuel line
above the 1/2 fuel point of the tanks. Look carefully at the fuel selector.)

Others have addressed some of the questions not asked. :-)

Charlie