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From: "Ed Anderson" <eanderson@carolina.rr.com>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
References: <list-1088383@logan.com>
Subject: Re: [FlyRotary] Re: new hangar
Date: Tue, 2 May 2006 08:13:06 -0400
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Hadn't really thought about it, Bob.  But, I would say they need to be make 
out of SS (304, 316 or 321), would need at least a 30-45 deg angle to the 
cone and be a min of 0.090 thick.  The diameter would depend on the size of 
tube being used. I would think not smaller than around 2 1/2 - 3".  They 
would need some perforations punched in the metal before making them into 
cones.  The idea is to break up the shock wave but not seriously hinder the 
flow of gas.  This is the design that you see on the market for exhaust 
inserts.  See this URL

http://www.secureperformanceorder.com/dynatechstore/getproduct.cfm?CategoryID=30&ClassID=278&SubclassID=1309&ProductID=2476

(Note: need to past both halves of URL address into your browser's address 
window).


From what I think I understood in reading about exhausts, my idea was to 
have a series of cones in a tube such that the would form a series of 
expansion chambers.   The cone would force the exhaust gas against the sides 
of the tube (area between cone and tube), then expand into a chamber between 
a pair of cones and then again have the gas forced against the outside (to 
the tube wall) by a  cone and then into another expansion chamber. 
Supposedly this contraction/expansion is good for reducing the shock wave.

I do know that after several experiments that 1/8" thick stainless steel 
just won't stand up to the shock wave of a turbo block (without exhaust 
splitters) for any period of time if oriented perpendicular to the shock 
wave.


Ed
----- Original Message ----- 
From: "Bob Perkinson" <bobperk@bellsouth.net>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Tuesday, May 02, 2006 7:26 AM
Subject: [FlyRotary] Re: new hangar


> Ed,
> What would be the dimensions of the cones if someone were to make them?
>
> Bob Perkinson
> Hendersonville, TN.
> RV9 N658RP Reserved
> If nothing changes
> Nothing changes
>
>
>
>
>
>
> Sounds like the right formula, George - will wait for your project's 
> outcome
> before I try cones.  Yes, I did find some cone  inserts at $60.00 USD 
> each.
> I would need 4 for my two tubes - hummm makes one tube sound better all 
> the
> time.
>
> Ed
>
>>
>>> Just the shells, TJ, the 1/8" thick SS washers are history.  I have
>>> concluded that no reasonable thickness of metal will stand up to the
>> exhaust
>>> pulse for long if it is perpendicular to the shock wave.  I believe that
>> if
>>> I could shape them into cones where by the shock wave would hit the side
>> of
>>> the cone  at an oblique angle  would probably survive - now all I have 
>>> to
>> do
>>> is find some {:>).
>>>
>>> Ed
>>
>> Ed,
>> There plenty of SS cones available in 1.6mm, I'm using them in my exhaust
>> which is a joint venture design with Bill Jepson - the idea is to 
>> redirect
>> the shock waves but not restrict the exhaust, as you have alluded to.
>> George ( down under)
>
>
> --
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