Sender: <marv@lancaironline.net> (Marvin Kaye)
To: flyrotary
Date: Sun, 01 Jun 2003 22:25:52 -0400
Message-ID: <redirect-2370995@logan.com>
From: Ernest Christley <echristley@nc.rr.com>
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Subject: Re: [FlyRotary] Electric water pumps (again)
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Al Gietzen wrote:
>  
> 
> Even if the electric water pump should work, what is the reason to use 
> one? It would have to be less efficient. You are converting mechanical 
> energy to electrical energy and then back to mechanical energy? There is 
> going to be a loss at every conversion. So in the end you will be 
> sapping more energy from your engine to power the water pump, power that 
> could be going into your prop.
> 
> 
> Perry;
> 
>  
> 
> What you say is true, but there may be something else to consider.  The 
> engine may not (does not) always require the full amount of flow 
> provided by the mechanical pump.  It provides enough for full time WOT 
> operation at sea level (presumably).  So if one had suitable control for 
> the electric pump (big IF); then other than takeoff and climb, we might 
> have a chance to save some power with an electric pump.
> 
>  
> 
> Al
> 
>  
> 
>  
> 

No I think the problem is that the mechanical pump is designed to 
provide enough flow at idle when the engine is hot.  The translates to 
WAY to much flow at 5000RPM.  You're wasting energy on the high end, but 
the car engine isn't engineered to hover at that speed.  It's designed 
to rev up there only momentarily and then drop back down to around 2500 
or so.

-- 
----Because I can----
http://www.ernest.isa-geek.org/
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