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From: "George Lendich" <lendich@optusnet.com.au>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
References: <list-1454240@logan.com>
Subject: Re: [FlyRotary] Re: Exhaust Update
Date: Wed, 11 Oct 2006 07:00:34 +1000
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Ken/Buly,
That should have read 4 tacks of reasonable length " on the outside", in 
case there was confusion.
However those in the know seem to be 'singing from the same sheet of music' 
so there is a strong consensus here.
George ( down under)

> Ken/Buly,
> The Mazda's high heat has proven to cause cracking at the joint of the 
> exhaust flange to the exhaust pipe UNLESS there is room to expand and 
> contract due to the heat cycling. Welding the inside and only having four 
> tack welds of a reasonable length, have proven to be satisfactory and 
> better than full welding inside and outside the flange.
> There are other methods which separate the pipe from the flange - such as 
> the motorbike style fitting, where you have a small round tapered flange 
> which is captured by the larger flange( clamping action), as it is bolted 
> up. This would be my preferred style of fitting, which would completely 
> eliminate the pipe cracking  problem. The muffler would need to be 
> supported independently, which is the preferred method anyway.
> George ( down under)
>
>> On Oct 9, 2006, at 11:15 PM, kenpowell@comcast.net wrote:
>>
>>> Hi Joe,
>>>  Just a heads up - it looks like your new "header flange to  pipe" 
>>> (picture 5) was welded on the outside.  I think that  'acceptable 
>>> practices' state that there should only be a tack weld  on the outside 
>>> and the actual structural weld should be on the  inside.  What does 
>>> everyone else say?   In any event be sure to  keep an eye on the welds.
>>>
>>> Ken Powell
>>> Bryant, Arkansas
>>> 501-847-4721
>>> C150 / RV-4 under construction
>>
>> Ken, I had the chance to inspect hundreds of aircraft exhaust systems 
>> from C-150 to the big twins. On 99% of them the flange is welded on  the 
>> outside. I have seen only one model aircraft that requires  welding on 
>> the inside only?
>> Buly
>>
>> --
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>
>
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