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and the continuing
story....
Boy did this one ever drag out but it appears to be a happy
ending. I will start from somewhere near the beginning as I see Jim is back
and not completely up to speed on the story, (by the way Rusty, spring is
usually here by the last week of June:-) About 6 weeks ago I had my first EWP
seizure while ground testing. I informed Leon and he immediately sent me a new
pump. In the meantime I freed up the old pump and used it to recirc a bucket of
water for ~6 hours with no problem, so I reinstalled it so I could continue taxi
testing. When the pump failed to show before I was ready for flight I decided to
go with the existing pump. It performed well during initial flights but as we
were taxing for flight #5 it seized again. So now I'm fed up with this and won't
fly with this pump again so I e-mail Leon who tries to track the pump with no
luck, It's vanished. No problem, it was insured so he sends another which should
be here in 6 days. Well after 3 weeks this one has not arrived so I ask Leon
again. I get the tracking # and search the post system from both ends. Nothing.
I phone Canada Post and find out that Australia Post had been using a company
called DDL to do their Canadian deliveries but as of Sept 16 Canada Post was
taking over but they couldn't help me with shipments before this. I tried to
find DDL using Google but all I got was an amazing number of porn sites (I don't
even know what a DDL is in porn?) Meanwhile Leon has sent yet another pump by
FedEx.
At about the same time I get kinda curious about the old pump which I'd
not dissembled as I was supposed to return it for warranty as soon as I'd
received the replacement. So I begin to disassemble and found a few minor
problems but one in particular that I feel was undoubtly the cause of the
seizures but was very easy and simple to fix permanently. So back into the plane
it goes again for ground testing (I needed to do some tuning on the
EC2).
Now I know that another one is on the way via FedEx, which has that handy
tracking feature on the web site letting you see it's progress. By Saturday
morning I can see that it is in Vancouver, Canada which is a mere 400 miles away
and it has cleared Canadian customs so I call and arrange for my test pilot to
fly up here on Tues. Sunday morning I check the web site and find the the pump
is now in Los Angles awaiting clearance by US customs. Sunday night it is now in
Memphis, TN and I'm starting to get a little pissed about the situation. Monday
morning it's in Spokane, WA. Monday noon it's back in Vancouver awaiting Customs
clearance again. This time they phone me and want money for taxes. I explain
that it is clearly marked as a warranty item and therefore no taxes should be
owing. They fuss about this and say they will have to put a trace on it to
confirm? More delay.
As I was certain that I'd solved the seizure issue, I felt it was
reasonably safe to proceed with another test flight. As you've read by now
flight was a success and pump is working great, so now that I may not need a new
pump of course the new pump shows up this afternoon. Go Figure? A big thanks to
Leon who kept sending the pumps.
OK for those who don't care about my shipping blues, about the pump....
Previously I was a little hesitant to trust using the EWP temperature controller
to control the pump speed so I would run it on bypass ( full 12v to pump motor).
I have now installed a Signet paddle wheel sensor into my cooling line. This was
a fair bit of work as I built a "T" fitting that would allow me to measure
without restricting. It also has the benefit of allowing me to fill the cooling
system from the bottom up, absolutely ensuring no air remains trapped in the
system. Currently I just have the frequency output from the sensor as I'm
waiting for a freq-voltage converter chip to arrive then I can build a small LCD
to display a flow rate, so right now I have a Fluke multimeter in the cockpit as
a flow indication.
Converting the frequency output to flow
shows that at full 13.8 vdc the flow was approx 45 litres/m. When on auto the
controller was pumping full flow during a full power climb out. Temps stabilized
at 100C during full power climb, but during full power level flight at higher
airspeeds, temps dropped to 80C and pump controller reduced flow to approx 30
litres/m. When using cruise power flow was <20 litres/m. During descent flow
dropped to <10litres/m to maintain temperature. During my first flight of the
day I concentrated on testing this and am very pleased with the results. At high
altitude it appeared to be able to easily handle cooling during during full
power, full boost climbs, but the air was cooler and we were making less
power. At low altitude full power, full boost climbs, cooling was adequate but
required full flow. I suspect that coolant flow has less to do with this than
rad efficiency. I will test to determine how much a higher climb speed will help
this.
I
had wired in a dash mounted potentiometer to the pump controller, to allow me to
control the coolant temp. It turns out to allow me to control from 80C up to
95C. I usually keep it down at 80C, but on a long cross country I may realize
some slight fuel savings by running up around 90C ?
Now that I have a replacement pump, I should install it and send the
original back, however since the original is now fixed and working
great, I'm contemplating just sending the money for it and keeping one as a
spare. I made an aluminium "T" to split the coolant flow for a parallel
installation and fabricated a "T" with a built in flapper valve (to eliminate
the weight of 2 check valves) to combine the flows. This would allow for one to
be used as a controlled main pump, with the backup just having a on/off switch.
Both pumps, controller and "T"s will still weigh half what the mechanical
pump weighed. At the moment I'd rather keep it simple and just use a single
pump, but I have everything ready to run a dual system if
necessary.
I
realize that testing is far from complete but this should be enough to prove
that an EWP can work in an aircraft without consuming vast quantities of power.
While I was getting a little frustrated at an empty mailbox everyday (well not
quite, plenty of bills), I'm glad I didn't give up on it as I'm very
pleased with the EWP.
S. Todd Bartrim
Turbo 13B RV-9Endurance
C-FSTB
http://www3.telus.net/haywire/RV-9/C-FSTB.htm
"Whatever you vividly imagine, Ardently desire, Sincerely believe in,
Enthusiastically act upon, Must inevitably come to pass".
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