Thanks for that link; I've been sorely
tempted to do it, but the hassle of removing an RV7 tank for
service (*much* worse than a -6) finally made me give it up. If
there was a convenient place for a 'header' tank in an RV, I'd
still give it some thought.
I'm sure that Steve already knows this, but a heads-up to anyone
else thinking about doing this. The web page for this controller
says 'just about any 12V pump will work'. NOT true. Several years
ago, I spent some time on the phone with a Walbro engineer
discussing the PWM control idea. He was very clear that the GSL
series pumps that most of us have installed should not be used
with PWM controllers. The reason he gave is that gerotor style
pumps (and I suspect this would also apply to roller-vane pumps)
can have relatively short lives if PWM-controlled, because the PWM
signal causes the gears to 'hammer' against each other.
The proper style pump for PWM is a 'turbine' pump. The pump is
basically a fan on the end of the motor shaft; works *kinda* like
a water pump impeller. Which brings up another caution about the
info on that web page. They show a turbine pump installed as an
in-line pump; an application you will never find in a car. They
are probably getting away with it in the bike because the bike's
fuel tank is higher than the pump. Turbine pumps are not
'positive displacement' pumps like the gerotor pumps; they cannot
'lift' fuel or self-prime. So installing them in-line in a low
wing a/c could be very hazardous.
Just thought the above was worth mentioning.
Charlie
On 1/20/2020 11:57 AM, Steven W. Boese
SBoese@uwyo.edu wrote:
The following site lists an inexpensive fuel pump controller
for use on a returnless system.
I have purchased one of these and am
in the process of installing it my rotary engine test stand for
evaluation.
Steve Boese
Ed did
use a very small header tank; logic was that the
recirculated fuel never stayed in the tank long enough to
begin to heat up. But he didn't vent the header back to
either main tank. I always thought that the unvented
header was going to be the cause of his next 'glider'
flight. If you add a vent line back to the main tank,
it'll work safely. (My BD4 had a similar system, but for a
different purpose; the BD main tanks had a tendency to
unport in uncoordinated flight.)
There are
other options, too. We can talk.
What is the best method for
handling return fuel in a high wing? Fuel return to
a small header tank sized to keep fuel temperatures
low? I think Ed Anderson may have used a small
header in his RV6.
Asking for a friend with an
airplane addiction.
Bobby
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