Based on Todd's correction of the earlier unbelievable numbers on
current drawer, you can expect somewhere in the neighborhood of 35-40
amps continuous for 25 gpm of flow (which is believable) - if the pump
will produce that much flow in a real cooling system.  That's based on
the pump power going roughly as the square of the flow rate.  

Al

 

-----Original Message-----
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net]
On Behalf Of Todd Bartrim
Sent: Saturday, November 06, 2004 1:28 PM
To: Rotary motors in aircraft
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

http://www3.telus.net/haywire/RV-9/C-FSTB.htm

 

             "The world will always have a place for those that bring
             hard
work and determination to the things they do."