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Date: Fri, 27 Jan 2012 13:17:21 -0500
From: Ernest Christley <echristley@att.net>
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To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Re: engine exhaust
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Rogers, Bob J. wrote:
> If you add another turbo to capture the remaining exhaust gas, the
> compressor portion will generate compressed air, which can be directed
> to flow over an oil cooler or a radiator, but the air will be much
> hotter than the outside air available for cooling.  When the air is
> compressed, it is heated by as much as 100 degrees.  The temperature
> rise is a function of the amount of compression.  That is why you need
> an intercooler before such air is routed to an engine intake for
> combustion.  I doubt that the air from a compressor stage of the turbo
> would be cool enough to help reduce the water or oil temperature very
> much (if at all) and the volume of air would not be significant compared
> to the volume of air available in the free stream of outside air.  Plus
> you have the added weight of the turbo to deal with.  In short, it would
> not work.  
> 

That setup wouldn't.  The compressor will also generate a vacuum, though.  Put it behind the rad to increase the dP and
you allow for a thicker rad.  You can then duct it so that you pull cooling air from a detrimental high pressure point
on the airframe...one of those points that slow the plane down.  You'll definitely need a larger compressor, and you'll
have to watch for exhaust back pressure, so an OTS solution is probably out of the question, unless you can frankenstein
the front end from a large diesel onto a 13B sized backend.