Mailing List flyrotary@lancaironline.net Message #42816
From: Mike Wills <rv-4mike@cox.net>
Subject: Re: [FlyRotary] Exhaust Progress
Date: Mon, 12 May 2008 19:47:18 -0700
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Doug,
 
 Read my post regarding my airplane empty weight from yesterday. My empty weight is about 75 pounds above Tracy's and I know for sure some of that weight is in the exhaust. I'd highly recommend stepping up to 321 and going down in wall thickness to save some weight. Those incremental increases really add up and using .120 your exhaust system is going to be HEAVY.
 
 As you can tell I'm not real happy about my empty weight. No doubt it will still fly fine as it's still 30 pounds lighter than my 160HP Lyc RV-6A. But I'd still like it to be lighter. I didnt think I was building that heavy. No idea where I will lose 75 pounds but I am going to be looking over everything with a critical eye.
 
Mike Wills
RV-4 N144MW
----- Original Message -----
Sent: Monday, May 12, 2008 6:53 PM
Subject: [FlyRotary] Exhaust Progress

 
I have finally cut had the time to cut out the 304 SS (.120 thickness) I purchased some months ago and am now ready for my welding buddy to bring his TIG welder over and tack it up.  The overall length is about 22" on the firewall side pipe, but 21.25" on the "front" pipe, so I plan on cutting the collector about 3/4 inches long on one side to even them up.  Overall the collector will have to shortened up considerably to achieve the more optimum 24 inch length Lynn has talked about for lower RPM / HP applications such as mine.  
 
Maybe Lynn could chime in here and comment on where on the collector that 24 inch point should be located for 5500-6000 rpm operations.  Hopefully where the collector first opens up between the two pipes...
 
If that isn't the case it won't be possible to hit the "optimum" point.  I also am planning on putting a ball joint of some type (type sold by Spruce) at the end of the collector before takes a 90 turn down followed by another 90 degree turn to direct it down the middle of the fuselage to the Spintech muffler I received with the engine.   Anyway, slow progress but at least some progress...
 
Doug Lomheim
RV-9A, OK City, OK
 
P.S.  I didn't have enough hands to really position it all perfectly on angle but hopefully you get the idea...
 




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