Looking for a reversible fuel transfer pump

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Jim Carriere wrote:
I've been toying with that idea for a while. You mean engine oil,
right?

Yes

Are such things at all common?

No, they are very uncommon.

I guess what I most wonder is
why, on GA aircraft with aircooled engines, are exhaust heat muffs
and/or fuel fired heaters commonplace.

Intentionally having a gasoline fire in the cabin was never my favorite

Which is worse, the
possibility of CO in the cabin or hot oil in the cabin (and possible
loss of powerplant lubrication)?

Velocity does it as a standard thing, they put their main oil cooler in
the nose an pipe hot oil to it from the engine. That always made me
nervous, though they haven't had a problem with it, and they put the
hose in conduit. I'm using an electric pump instead. I'm running much
lower pressure (just enough to overcome the friction of the oil moving
in the hose) and if it springs a leak, I can turn it off.

I'm also drawing oil from the side of the sump. There's space beneath
it for about 3 quarts, and another quart or so is in the upper part of
the case during flight. Lycoming says the engine can run without
damage on 2 quarts total.

In the worst case - a fitting fails just downstream from the pump, and
dumps oil in the back seat where I wont see it - the system will only
dump 2 quarts before the port is uncovered.


Seems to me that safety/reliability issues can be addressed by using
quality parts and design. The functionality issue is maintaining the

oil at operating temp, on a cold day or fast/high cruise, when cabin
heat is most needed and the engine does not want to run hot (cowl
flaps?).

When you're high cooling actually gets harder, because the air is thin.
The vernatherm will progressively cut off the main oil cooler as the
engine runs colder, but my cabin heat exchanger is only about 20% of
the size of the main. And my pump is putting out about 30-50% of the
volume of the engine oil pump. So I *think* that the total heat I'm
scavanging is not significant. If I find a part of the envelope where
it is (ultra-cold day, low power setting, low altitude) I can turn it
off, and I'm no worse off that I would be without it.


In other words, what am I missing? Thoughts anyone?

wrote:
X-No-Archive: yes
pretty thorough explanation

Hmm... neat! thanks for answering my question so well. It would
seem to me that you really did your homework. In particular I like
the idea of drawing from the side, instead of the bottom, of the sump.

At first glance I wondered why you chose to use a separate pump for
your heater design. I figured it would be better for the heater flow
to piggyback off the engine's normal flow (same as coolant based
heaters). But I see the wisdom in your setup isolating the heater
with it's own positive pump. As you said, the normal failure mode is
no cockpit heat for the rest of the flight and the loss of less than
a critical amount of engine oil.

"Richard Riley" wrote

2) The fan drove me nuts for a long time. Finally I found a bilge fan
from a boating supply store http://www.boatersland.com/rul140.html
that's 12 volt, lightweight, and has plenty of volume. Don't bother
with cooling fans from computers, they don't blow nearly enough.

It is not a question of "enough." The computer fan is only good at moving
free air, and does **** poor at pushing through any resistance, such as
blowing though the fins of the heat exchanger, and any bends and kinks of
the ducts. The squirrel cage blower is made for pushing pressure; that is
why they are always used in furnaces.

Simply a case of proper application, but you knew that, right? :-)

Good idea using a bilge blower. One h*ll of a lot lighter than an
automotive blower.

I think I missed something. Is this on a flying application, so you can see
if it puts out enough heat, oil heat wise, and volume wise?
--
Jim in NC

"Richard Riley" wrote

The bilge fans are axial, like the muffin fans, but
with a lot more power. The blades have about 6 times the chord of the
muffin fans, and they have long shrouds.

I've never seen a blige blower that was axial, but I've not seen that many.
Learn something new all of the time.
--
Jim in NC