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Message
Hi all,
maybe I missed it, but for what reason would you
want to run electric waterpumps?
There will never be a moment where you could shut down any or all for more
than a few seconds, so saving fuel/power is not the reason. If you need a
constant flow of water, why would you want to route the necessary energy from
the engine/to the alternator/to the EWP, instead directly from the engine to the
WP?
Belt brakes what then? When was the last time a belt broke in your car?
Redundancy? Buy/have it made a set of 2-belt pulleys and exchange the first belt
at 400 hrs or 4 years whatever hits first. This way you have a new belt and an
old one. If the old one ever brakes you the second one to keep you good until
you get there. Change it anyway at 1000 hrs or 5 years.
Is there ANY vehicle out there that relies on an EWP for its cooling
turnover - air, heavy industry, mining, trucking, boats, ships, anything?
........please forget about racing applications, except you're building a
raceplane:)
I know there are aftermarket intercoolers that use a watercircuit with
electric pumps, but are these constantly running? ....do these turn over that
much water?
Back to the belts: Robinson Helicopters relies on belts to transmit 180hp
and 280 hp. These belts are lightweight and easily last 2200 hrs or 10 years,
additionally they are used as a clutch to engage the rotor, average about once
every 1 1/2 hours of flight time! If electric drive would be that much
better/lighter/cheaper/safer (pick any one or all!:) they would run it
electric!!
Maybe a good discussion for the heck of it and to check the merrits of it,
but I seriously hope no one thinks about flying over hostile terrain with an
electric only cooling setup!
Personally I think a dual belt set-up is more than enough, but if you want
hardcore I'd do dual alternator/waterpump with dual belts (a total of 4 belts),
but not electric!
Your alternator goes (and mostly it doesn't because of the belt, but burned
circuits, diodes, voltage regulators, etc.), your EWP goes soon too! How long
will your engine run on the battery which already supplies
ignition/fuelinjection/fuelpump/radios/nav. Now you want to use another2-3 hp
out of it? Well a bigger battery will need a heavier alternator!
Besides it is way easier to check belts than to check the condition of an
electric drive....
I don't want to spoil the discussion, but it points into the wrong way
safetywise!
You are after a racer or something else special, sorry I didn't catch it or
signed on too late to get the start.
But as a general means to pump the cooling through a Rotary, no
thanks!
Again, check where, anywhere electric pumps are used for longterm, non-stop
cooling - I don't think Aviation should be the testing ground for a "first
time!"
(Please don't tell me about oceangoing ships, there things are a little
bigger and heavier and there are at least 2 pumps redundant for EVERY pump in
action, AND they do fail quite often, though not because of electrics, but
foreign objects in the pump, cavitation and erosion damage...)
Thomas Jakits
----- Original Message -----
Sent: Saturday, November 06, 2004 4:27
PM
Subject: [FlyRotary] Re: EWP
Whoaa, before anybody gets worked up over my current draw figures, I'd
made a mistake in my report and had sent another post correcting it the next
day. Below is the corrected post.... hmmnn, is there a way of going back into
the archives to correct erroneous data, as this same issue came up once before
based on my incorrect data post.
Hi
Guy's
I had a hard time
believing the current draw for the pump so I brought home my good "Fluke"
multimeter from work. The one I used last night was a cheap Digital meter from
"Canadian Tire". I seldom use this one, so I'm not familiar with it but since
it is very similar in outward appearance to my "Fluke 87" I assumed the same
functions would apply. They don't.
OK,OK, enough excuses, now for the real
current draw.
- continuous current draw - 4.3 amps
- max inrush current draw at 100mS - 6.8
amps
- max inrush current draw at 250uS - 13 amps
- continuous current draw at minimum controlled flow - .2
amps
The max inrush current is not really relevant to our
concerns, but there it is for those that care.
This higher current flow is still well within acceptable
limits for my needs, and I expect that while in cruise flight, the controller
will be reducing pump speed and current
draw.
I've reposted the
flow measurements along with this post with the incorrect current draw
deleted. I hope this clears up any confusion about EWP current requirements.
I
I ran the first test
with the Ford evap cores in the system, plumbed in
parallel.
- Max flow 9.3 usg/m 35 l/m
- 12.07 volt battery supply voltage
Second test had no evap
cores in the system. Simply recirced water through pump - engine - header
tank - pump.
- max flow 13.0 usg/m 49 l/m
- 12.06 volt battery supply voltage
Third test, I plumbed in a
set of GM (Harrison) evap cores in parallel, into the system. I hung them
just below my mounted Ford cores, using they same pipe sizes in an effort to
have comparable test conditions.
- max flow 7.7 usg/m 29 l/m
- 12.4 volts supply voltage (I hooked a trickle
charger to the battery)
In each test configuration
test results are with heater valve closed. Heater core added .5 usg/m in
each case.
In all of the above
tests the electronic pump controller was bypassed to give full battery
voltage to the pump. With the pump controller in use, as the water was
cold well water, controller had pump at minimum flow which was measured
at .6 usg/m - 2.2 l/m.
I've just been lurking since returning from school as I've got
allot to catch up on around here, so am trying not to get distracted with
the list, however I needed to jump in on this one. I need to head out to the
airport today to install my new radio and hopefully get out for a flight, as
they are calling for 5" of snow tonight.
Todd Bartrim
RV9Endurance
13B Turbo Rotary
C-FSTB
"The world will always have a place for those that bring hard work and
determination to the things they
do."
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