Sender: <marv@lancaironline.net> (Marvin Kaye)
To: flyrotary
Date: Wed, 16 Oct 2002 21:58:59 -0400
Message-ID: <redirect-1830278@logan.com>
From: "Mike Wills" <willsm@spawar.navy.mil>
Subject: Re: [FlyRotary] EWP Tech Data
In-Reply-To: <list-1830167@logan.com>
Mime-Version: 1.0
Content-Type: text/plain; charset="us-ascii"; format=flowed

At 07:38 PM 10/16/2002 -0400, you wrote:
>   From
>the data, it appears that the Davies EWP can do the same cooling job for
>approx 105 watts of energy (7.5 amps x 14 volts = 105 Watts).  6000 watts =
>approx 8.5 HP or say a net gain of 6000-105 = 5895 Watts = 7.9 HP.
>
>  It appears that the crucial difference is that the assumption was made that
>6000 watts constituted the power required to drive the coolant at those rpms
>to assure adequate cooling.  What the Davies charts seem to imply  is that
>most of that energy is wasted by a mechanical pump (at that engine rpm) and
>is simply unnecessary
>friction and head pressure losses.
>  I know, I know - my skepticism is still showing through and I'm not even
>from Missouri {:>).  But, I am convinced that previous discussions about the
>viability of the EWP may have been based on flawed assumptions and the topic
>deserves another look.
>
>So, Todd, based on this technical data, it appears that I may have been off
>in
>left field on my comments about the practicality of the electric water pump
>for aircraft application.  However, I will truly be convinced when we get
>your data.  Looking forward to your results.
>
>Ed Anderson

Ed,

  So based on your analysis of the Davies Craig data the EWP is about 57 
times as efficient as a typical mechanical pump? Some improvement in 
efficiency over a belt drive wouldnt surprise me, but 57 times as 
efficient? That would be a shocking improvement in efficiency. You'd think 
that the OEM's would be all over that.

   I truly hope that Todd's experiment with the EWP works out. If he flies 
with it and is able to successfully cool his airplane you can count on my 
order. And unlike some people, I'll be happy to admit I'm wrong. Meanwhile 
I think I'll maintain a healthy dose of skepticism.

Mike Wills