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Date: Thu, 03 Mar 2005 14:03:18 -0500
From: Ernest Christley <echristl@cisco.com>
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To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Re: EWP Test Results/DRAG
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kenpowell@comcast.net wrote:

> I think Al and Bill have been trying to say this politely but ....   
> We all agree that the EWP flows less than the standard pump by alot 
> (maybe only half to 1/3th as much?). 

I don't know that I agree with you there, Ken.  If the EWP works through 
the same flowpath as the EDWP, I think your statement is accurate, but 
the EWP's form factor allows for some ingenuity in creating a less 
restrictive flowpath. 

The numbers I've found quoted for actual back-to-back dyno runs 
comparing the EWP to stock pumps show benefits from 4 to 9 Hp.  (a 
Google search 'meziere pump performance chart' will show several)  These 
numbers are not for 13B engines, and probably have a lot of 'marketing' 
in them ('cause we all know magazine reviews are objective. Right?), but 
I'd still consider the ~3Hp gain conservative.

Most importantly, Bob's numbers were raw data and not corrected for 
actual conditions.  The realworld conditions will be much more favorable 
than his test.  If I may be so bold as to shamelessly rip some 
information from different places without giving due credit:


    Poiseuille's Law of The *Flow* of Liquids Through a Tube:


    Where:

l = the length of the tube in cm
r = the radius of the tube in cm
p = the difference in pressure of the two ends of the tube in dynes per cm^2
c = the coefficient of *Viscosity* in poises (dyne-seconds per cm^2 )
v = volume in cm^3 per second


        Then:

v = pir ^4 p/8cl

*Viscosity of Water as a Function of Temperature*
Temperature
/°C 	Viscosity
/cP
20 	1.002
40 	0.653
60 	0.467
80 	0.355
100 	0.282


Pump A Only:
14.0 V   8.4 A   6      GPM  56 F

56F => 14C
180F => 82C

My reasoning:
All other factor being equal, cutting the viscosity to 1/3 will triple 
the flow.  If the WP136 flows 6GPM at 56F, it can be expected to flow 
18GPM at 180F, closer to 20GPM at 190F.

Ernest (also a true believer, but so were all those people at Jonestown)