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Date: Wed, 26 Jul 2006 19:17:34 -0500
From: Charlie England <ceengland@bellsouth.net>
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To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Re: Inconel
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Find an old Continental powered VariEze. Short stub (maybe 2 ") welded 
to the flange with 'eyelets' also welded to the flange.  Straight 
exhaust stacks (ID slightly larger than the stub OD) had 'eyelets' 
welded several inches down from the engine end. Stacks slide over stubs, 
butt against flange & are held on with springs. (A loop of heavy safety 
wire through the spring would probably be a good idea.)

The story I was told was that Rutan came up with this after several VE's 
had welded stacks break off & go through the prop. I heard this story 
about 15 years ago; things may have changed a lot since then.

Charlie

Ben Baltrusaitis wrote:

> Al,
> That strobe is a great idea!
> I'm going to do that. I appreciate all the knowledge you share.
> I'd like to see a pic of your slip fit exhaust. It seems to me I could 
> use a heavy piece of header pipe that goes all the way into the 
> muffler and a smaller walled piece for the slip fit with maybe a three 
> inch overlap.
> How do you stop the gases from leaking past the slip fit?
> Thanks!
> Ben
> Acroduster Too (still building)
> 20B
>
>     ----- Original Message -----
>     From: al p wick <mailto:alwick@juno.com>
>     To: Rotary motors in aircraft <mailto:flyrotary@lancaironline.net>
>     Sent: 07/26/2006 5:56 PM
>     Subject: [FlyRotary] Re: Inconel
>
>     I have a lot of experience with failure analysis. Used to do it
>     with GM, Ford, other warranty returns. One of my favorite
>     experiences was solving a million $ warranty issue on a tubing
>     product. Although I'm not expert in this area, I'd sure encourage
>     considering other factors, other solutions.
>     In particular I'd encourage use of strobe lamp. Take cowl off,
>     fire up engine, use strobe. (yes, it's dangerous with prop on) You
>     will suddenly have appreciation for the forces involved. You
>     should be able to predict failure points with this test. Tack
>     together the broken one to see what I mean.
>     The exhaust will turn into a sine shape at certain rpm. You will
>     see huge amount of movement on the busted one. Make a new design,
>     compare movement to predict how long it will last. A very minor
>     design change can greatly improve how much movement occurs.
>     I'm not sure this is applicable to you guys, but my exhaust design
>     has slip fit of two pipes instead of welding. It works phenomenal.
>     I've had conversation with other guys who welded instead and had
>     failures. Same exact application. So my exhaust floats in relation
>     to the header. I just attach a small bracket to the floating
>     portion to prevent if from blowing off. Truthfully, I never
>     expected it to work, but it has quite well. I might have pic if
>     verbal description not adequate.
>      
>
>     -al wick
>     Artificial intelligence in cockpit, Cozy IV powered by stock
>     Subaru 2.5
>     N9032U 200+ hours on engine/airframe from Portland, Oregon
>     Prop construct, Subaru install, Risk assessment, Glass panel
>     design info:
>     http://www.maddyhome.com/canardpages/pages/alwick/index.html
>