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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
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