Received-SPF: none
 receiver=logan.com; client-ip=68.230.241.31; envelope-from=daveleonard@cox.net
From: <daveleonard@cox.net>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Re: oi/water Exchanger  [FlyRotary] Re: fluidyne oil cooler
Date: Fri, 7 Jan 2005 20:46:50 -0500
MIME-Version: 1.0
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: 7bit
Message-Id: <20050108014653.NQFV27771.fed1rmmtao08.cox.net@smtp.west.cox.net>

I was considering the idea when I was planning my installation and one big question kept popping into my mind: which side of the rad do you put the interchanger?

If you put the interchanger on the hot water coming out of the block, that water is at least 180deg.  This hot water will have a very hard time cooling that oil, and best case could only get it down to 190 or 200.  Likewise the water is likely to boil before it get to the radiator since it is starting at 180 (at least) and going up from there.

If you put the interchanger after the radiator it will probably do a good job of cooling the oil, but now you will be heating the water right before it goes back into the engine.  In order to keep the water from overheating in the engine it will have to come out of the heat exchanger relatively cool, which mean it has to come out of the rad really cool.  To get it that cold comming out of the rad that cold (assuming you had a big enough rad), the temperature gradient really has to drop and the rad becomes very inefficient as it is trying to cool the coolant that extra 20 deg.

I decided the only efficient way to do it was to have two rads, one after the interchanger and one before it.  I suppose that would work if you were using 2 evap cores in series, but for me the obvious solution was to use an oil/air cooler.

Dave Leonard

>  
> Good points of course, but I still can't help but be drawn to the simplicity
> of having only one scoop, one duct, and one radiator.  Even as I type, I'm
> trying to figure out where I can put a bigger radiator (within cosmetic
> limits this time)  :-)    I'm even warming back up (so to speak) to the idea
> of using the stock 1st gen oil/water exchanger for the single rotor.  It was
> pointed out to me that the stock unit took hot water from the heater outlet,
> which doesn't really give the heat exchanger the best chance of success.
>  
> If I get Ken's oil/water exchanger, I'll be mighty tempted to hook it up to
> the current two radiators to see how it does on the ground.  Since I'm not
> opposed to changing out the evap cores, there might be a way to enlarge the
> capacity some.  Barring all that, it'll make a nice paperweight.  
>  
> Cheers,
> Rusty (now collecting oil coolers instead of manifolds)    
>  
>  
> 
>