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Date: Mon, 28 Feb 2005 14:42:50 -0600
From: Jim Sower <canarder@frontiernet.net>
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To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Re: [FlyRotary]Belt rumnations; soliciting Opinions
 of racers please....
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<... My guess is that the EWP will ONLY work if the water flow path is 
cleaned up sufficiently to allow it to work ...>
My guess is that we're pretty much clueless.  In a closed system, the 
only impediment to flow is friction which is largely a function of flow 
rate and some exponential function of the diameter of the "pipe".  The 
irregularities in our system are such that they render any attempt to 
compute total friction an exercise in mental masturbation.   What we 
need is some expire mental measurement of flow rate under actual 
conditions (which will involve a flow meter in the system) and then, 
with the engine at rest (the pump is the only moving part in the 
system), we can see how much current it takes to achieve that flow rate. 
Sadly, the pivotal instrument, a flow meter that doesn't disturb the 
system too much, is probably not available.  If someone could come up 
with a flow meter in a 1.25" line, we could do some expirements. 
Other than that, we're guessing at numbers like PL and the bumblebee 
folks ... Jim S.


Ernest Christley wrote:

> Paul wrote:
>
>> I have a small 12 volt bilge pump for my birdbath/fountain. Mfr 
>> claims it moves 640 gph of water.  If I divide gallons per hour by 
>> 60= gpm should work out to around 10.66 gpm. This is a tiny 12 volt 
>> bilge pump that my photovoltaic cell runs, with no battery. (only 
>> works when the sun is overhead). You can hold it in the palm of your 
>> hand nearly close your hand around it.  Seems like it wouldn't take 
>> much larger of a motor to push 30 gpm if this puny thing will pump 
>> 10+ gpm.  It will empty a bilge pretty fast. I realize this is 
>> unrestricted water, but still, it has to move all that water out of a 
>> boat bilge, and does a fine job. It pumps the water in my fountain 
>> too high, had to put a restrictor on it.  Paul Conner
>
>
>
> Paul, I think one of the factors often left out of the EWP/EDWP 
> discussion is head pressure.  GPH or GPM is meaningless without 
> stating what head it is pushing against.  I'm trying to remember this 
> off the top of my head, but I compared the water flow and current 
> measurments that Todd gave a while back with a chart that Davies-Craig 
> provided which showed flow vs current draw for various head 
> pressures.  I estimated then that Todd's system had about 9psi of head 
> pressure.  Most of the flow calculations I've seen arguing that the 
> EWP won't work use a figure of 30psi of head.  The two ain't the same 
> thing.
>
> My guess is that the EWP will ONLY work if the water flow path is 
> cleaned up sufficiently to allow it to work.  I think Rusty's 
> experiment with using both has a high likelyhood of failure, because 
> he will be using the EWP with the thermostat and the tortured path 
> that the EDWP forces the water through.  It will be overwhelmingly 
> convincing if does work with the odds stacked against it so much, but 
> at most will only be a qualified failure.
>
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>>
>
>