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Date: Sat, 19 Mar 2005 10:31:11 -0700
From: Bob White <bob@bob-white.com>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Re: Water Pump Viscosity Test
Message-Id: <20050319103111.0a235f44.bob@bob-white.com>
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Hi Jerry,

20 GPM was my design goal which was set based on Bill Schertz' analysis.
At that flow rate, it gives me room to accomodate some problems with
heat transfer and air flow.  I think Bill's analysis give a pretty
clear picture of what's needed.  If I go thru it and adjust for my
system, I get:  (All of the following is based on Bill's charts and
analysis.)

1.  Set the redline temp at 210.  That is Bruce's never exceed temp.
2.  For a 200 HP engine with a 50 F drop across the engine, I will need
     a flow of 15 GPM and 160 F water out of the radiators.
3.  On a real hot day (110F), I will have a 50F potential between the 
     outside air, and the air out of the radiators.

(both the air flow and temperature drop graphs stop at 50 F and the
curves are getting flat anyway, so these are probably the best worst
case conditions to consider.)

4.  I will need about 6500 CFM to accomplish that.
5.  Initially, I will make my cowl opening 144 in. sq. (two 8 X 9).
6.  With those openings, I can get 6500 CFM at about 90 MPH.

There may be some factor I don't know about which makes it work better
than calculated, but air flow or heat transfer problems  will definitely
make it worse.  Anyway, the test has answered the question about
viscosity which was really it's only purpose.  I feel a lot better not
having to guess about it.  :)  If I had seen a significant increase in
flow rate, I would be right at the design goal and I could have forged
ahead.  Now I'll have to think some more.  

At the moment, I'm leaning toward getting the WP336 which I think will
give me 16 GPM.  (It would be nice to test it.)  That should be an
adequate flow per the above analysis.  

If it weren't for the positive experiences of guys like Todd and Leon,
I wouldn't even be trying EWP's.  OTOH, I want to start with the system
as well designed as I possibly can.  It will be a lot easier to back
off if I have too much cooling than trying to get more.

Bob W.


On Sat, 19 Mar 2005 10:59:04 -0500
Jerry Hey <jerryhey@earthlink.net> wrote:

> Bob,  I appreciate the well thought out test although I am not ready to 
> say I understand its implications.  How much coolent flow is required 
> is related to other variables such as radiator size and air volume 
> passing through the radiator. It may  be the case that slower coolent 
> flow is preferable or at  least acceptable.   We know that the EWPs 
> will work if the other variables are optimised.  Leon’s racing 
> experinece with EWPs and Todds ability to cool a turbo with an EWP, 
> have me thinking that we need to focus on the other components of the 
> cooling equation and not worry about the  EWP.  Jerry
> 
> 


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