flyrotary@lancaironline.net Mailing List Archive

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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.

-----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."