Sender: <marv@lancaironline.net> (Marvin Kaye)
To: flyrotary
Date: Sat, 12 Oct 2002 00:33:36 -0400
Message-ID: <redirect-1803747@logan.com>
From: Wschertz2@aol.com
Subject: Re: [FlyRotary] EWP water pump
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Todd,
One thing that would be useful, is to make some pumping measurements off the 
engine (i.e. before putting it on the engine and having to run the engine.)

If you can set up a flow system, where the pump removes water from a 55 
gallon barrel, has a pressure guage on the output side, a throttable valve, 
and a means of measuring the flow volume (either a flow meter or a bucket and 
stop watch), you can get some very valuable data.

1. with the valve wide open measure the flow rate by turning on the pump and 
timing how long to fill a 5 gallon bucket. record the pressure guage reading.

2. partially close the valve, and repeat the measurement of flow and pressure.

3. close it some more and repeat

4 keep going in small increments. you should see a rise in pressure and a 
decrease in volume

5 last data point would be when the valve is totally closed.  Just record the 
pressure at no flow (stagnation)

What would a test like this show you (us) ?  It is how you generate a "pump 
curve", if you plot the pressure on the vertical axis, and the flow rate on 
the horizontal axis, the curve will start with some high pressure (max the 
pump can make) and the pressure will drop as the flow rate increases, until 
the valve is wide open.

So what? you may ask -- well the rest of the system that the pump has to push 
the water through -- (engine, pipes, rads) will have a pressure drop that 
starts at zero at zero flow, and rises as the flow through the system 
increases.  At some point the pressure drop in the system will match the 
pressure that the pump can deliver, and that is the actual flowrate that you 
will get in your installation.  

6. If you repeat steps 1-5 at a different dial setting, you will get a second 
curve, that is lower (if you have dialed down the pump setting), and you can 
read the flow that it will deliver in your installation, say for economy 
cruise.

The reason that this would be useful information, is it removes one variable 
from your consideration when you are running the system and trying to debug 
the cooling system.  You will know the flow rate that can be generated, and 
therefore whether it is a factor in your data, or whether the air ducting is 
more important.

I am very interested in ANY data you get, on or off the engine, since I have 
a space problem fitting the stock water pump.

(P.S. if you measure the voltage and current draw of the pump during the 
tests, you also can get a handle on the alternator load that you will have in 
the plane.

Bill Schertz
KIS Cruiser #4045