Mailing List flyrotary@lancaironline.net Message #28596
From: Russell Duffy <13brv3@bellsouth.net>
Subject: RE: [FlyRotary] Re: Heat exchangers
Date: Mon, 19 Dec 2005 19:48:22 -0600
To: 'Rotary motors in aircraft' <flyrotary@lancaironline.net>
Message
Random thought:  Very strange that Lynn and other car racers have not had a problem with the cores but you busted 2 of them.   
 
Hi Tracy,
 
I've pondered this question as well, and the only thing I can think of is the fact that racers don't sit at one rpm for any real length of time.  I wonder if the cores I was using just happened to have a resonant frequency that matches what you get from the oil pump at 6000-6500 rpm. 
 
When the first one failed, it was during high power ground runs, testing intakes.  I was running WOT, and playing with timing, mixtures, etc for as long as I could without overheating.   The second one was during steady cruise, at about 6500 rpm IIRC.  
 
Note that both coolers failed at the same seam, which is the one that's made by the end plate.  If you look at these cores, you can see that those seams are not the nicest looking joints you've ever seen.     
 
 BTW, your aluminum welding looked fine to me!  My AL welding looks like hell so far. 
 
Thanks, but when you figure there were 10 fittings welded, you can bet that the nicest one was closest to the camera :-)   I look at the Fluidyne coolers in I'm just in awe of the welding skill that I see.  I really wish I had someone locally to show me how to go from "works", to "proper".  Pity Ed K is about as far away as you can get, or I'd pay to watch him weld aluminum, and hope some of it rubbed off on me  :-)
 
Cheers,
Rusty (still hoping to run the single rotor by the end of the year)
 
    
 
 
 
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