----- Original Message -----
Sent: Saturday, November 06, 2004 10:13
PM
Subject: [FlyRotary] Re: EWP
Hi all,
maybe I missed it, but for what reason would
you want to run electric waterpumps?
One of the primary reasons is that the electric
water pump is an on demand system. When the engine is at idle, the mechanical
pump slows down. With an electric water pump and the engine at idle, the pump
will increase flow as the engine gets hotter. Not possible with the electric
water pump. You would need extra radiator fans, etc.
Belt brakes what then? When was the last time a belt broke in your car?
Last Sunday....Had to take a taxi to AutoZone to buy a new belt.
Two weeks prior to that, the water pump failed in my Dodge Caravan. Overheated
rather quickly.
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:)
Yes...there are two Ford Mustangs that I know of
using EWP's. They drive them to work daily.
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!
Unfortunately, it's already being done, with a
Mazda 13b. His name is Todd.
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...)
I work as a mechanic, and I find that one of the
least reliable, and most likely items to fail on an engine is the mechanical
water pump. Check with other mechanics. I think you will find most
will agree. Paul Conner
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."