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From: "Ed Anderson" <eanderson@carolina.rr.com>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
References: <list-1021775@logan.com>
Subject: Exhaust Splitters - Lynn??
Date: Sun, 26 Jun 2005 08:46:00 -0400
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 >
> OK.  I'm about done digesting, so...
>
> This is completely logical, under the theory that the sharp edge will trip 
> the exiting airflow into turbulence.  Clean air always flows faster.  I 
> keep thinking about the exhaust inserts. Ed has the opinion that they must 
> be eating up horses to give the noise reduction by causing back pressure. 
> But what if the inserts work like a fowler flaps and just helps the gas to 
> exit is an orderly manner vs all turbulated?  Aren't laminar flow aircraft 
> typically quieter than turbulent flow ones?
>
> Has anyone compared the noise produced before and after an exhaust has 
> been radiused?
> Has anyone attempted to 'shape' the inserts so that it has a radiused 
> leading edge and a tapered trailing edge (ie, aerodynamic)?  I know 
> they're not very thick, but their thickness is a significant portion of 
> the overal exhaust ports size.
>
> -- 
The Mazda data shows a 8 db decrease in noise energy using the splitters, 
since this is probably "lost" energy in the first place - being exhaust 
energy, I am certain that the power is not down by 8 db {:>).  However, 
others, including Bruce T have suggested that they cost approx 15HP at 
higher rpms (RPM not specified). I have not seen any dyno data that would 
provide enlightment on this question.   Lynn do you folks race with exhaust 
splitters?


Ed