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Date: Sun, 24 Oct 2004 11:12:43 -0500
From: Charlie England <ceengland@bellsouth.net>
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To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Re: oil cooler duct suggestion
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Russell Duffy wrote:

> My impression is that Rusty 1st objective is he would like for the oil 
> temps to be lower. 
>
> You're very perceptive :-) 
>  
> Thanks very much to all for the comments.  After looking at my drawing 
> some more, and comparing it to the pics of the cowl, I can see that I 
> wasn't quite as accurate as I could have been.  Primarily, the core 
> isn't parallel to the incoming air as the drawing showed.  I'll attach 
> some actual photos of the scoop, to give a better idea.  They've been 
> compacted, and enhanced a bit to make the details show up better.  
> Kinda hard to see much contrast in that poop colored epoxy. 
>  
> I was never quite happy about the way I left that flat wall in the 
> rear end of the scoop, and I almost smoothed it out a month or so 
> ago.  What I was planning to do, is very much like what Ed showed in 
> his blue markings.  I would never have thought to include any sort of 
> divider.  From what I've seen, I think I'll probably smooth out the 
> rear of the scoop first, and see what that gets me.  I can add a 
> divider if needed later.  When I have the cowl off, I can place some 
> thermocouples around the core to see what the delta T is. 
>  
> One other thing I should note- the exit side of the core is pretty 
> ugly.  Unfortunately, to get it in the stock cowl, I had to leave only 
> a few inches for air between the core, and the oil pan.  I'm sure 
> that's not helping me any.  The only fix to this is to reposition the 
> core, which will be far more hassle.  Hopefully, I can compensate with 
> the scoop shape. 
>  
> Thanks again for all the comments.
> Rusty (currently raining)


Two thoughts (my limit for a Sunday):
The inside of the inlet lip looks like it's rather sharp. Does it need 
rounding like the regular cooling inlets on RV's? Most aero gurus say 
that sharp edges cause turbulent flow in the inlet.

Did you do anything inside the cowl to keep radiant heat from the oil 
pan off the cooler? A sheet of .020 AL suspended 1/2" below the pan 
might keep quite a bit of heat out of the cooler.

OK, 3 thoughts but I'm over my limit:
Tracy Saylor, of  extremely fast RV-6 fame, says he has curved turning 
vanes on the *outlet* side of his cylinders to direct the air toward the 
exit, rather than letting it hit the bottom of the cowl. Could that idea 
be used to both direct the exit air & provide a radiant shield?

Charlie
(never flown a liquid cooled anything, except that brief excursion in a 
Malibu off the road into a power pole when I was 19....)