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From: "Ed Anderson" <eanderson@carolina.rr.com>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
References: <list-963530@logan.com>
Subject: Re: [FlyRotary] Re: Suitability of NPG for Rotary Engine use
Date: Wed, 1 Feb 2006 11:52:35 -0500
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----- Original Message ----- 
From: "Ernest Christley" <echristley@nc.rr.com>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Wednesday, February 01, 2006 11:36 AM
Subject: [FlyRotary] Re: Suitability of NPG for Rotary Engine use


> Ed Anderson wrote:
>
>> Attached is some supporting (I believe) facts to support this opinion 
>> (and that is all it is).
>>  Ed
>>
>
>
> Concerning the change in the heat removal between NPG and NPG+.  Did you 
> take into consideration that the NPG+ is more dense?
>
> What is the limiting factor on the rotary heat range?  Would seals made of 
> materials rated for higher temps solve all the problems?   If it were 
> possible to run a significantly higher temp coolant through the radiators 
> it could reduce coolant drag.
>
> -- 
>         ,|"|"|,               Ernest Christley     |
> ----===<{{(oQo)}}>===----     Dyke Delta Builder    |
>        o|  d  |o          www.ernest.isa-geek.org  |

Ernest, my admittedly limited understanding of thermo properties leaves me 
to believe that specific heat already takes into consideration the different 
in density.  In otherwords, the specific heat factor specifies how much heat 
it takes to raise a fixed amount of a material (cubic CC?) 1 degree. 
Therefore, the role density plays is already taken into account by 
determining the specific heat of the material.  At least that is my 
understanding.

I am not certain that there is just one factor that limits the safe 
operating  temperature of the rotary.  I suspect that one of the major 
factors is the different coefficients of expansion between the iron side 
housings and aluminum rotor housings. Also, recall that coolant flows pass 
the front rotor first so is already heated before it encounters the rear 
rotor - not the best approach from a cooling perspective, but probably the 
easiest manufacturing approach.

 I have also read that higher temperatures causes the apex seal to chatter - 
so perhaps that is a limiting factor.  Certainly, higher temps seals (TES 
Coolant "O" rings for example) helps, but I just don't think they are the 
only factor.

Ed