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Date: Sat, 11 Dec 2004 16:14:16 -0700
From: Bob White <bob@bob-white.com>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Re: exhaust design question
Message-Id: <20041211161416.00d9e21c.bob@bob-white.com>
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Hi Jesse,

Try http://www.bob-white.com/enginerun.WMV for the Mistral engine
running in the Arrow.  It's about 2 Mbytes

Bob White

On Sat, 11 Dec 2004 15:08:05 -0500
"jesse farr" <jesse@jessfarr.com> wrote:

> That sounds like one of those 'you just had to be there' sounds, to
> me. <g> Doesn't someone have a web page with a rotary sound, other
> than Tracy's flyby ?
> jofarr, soddy tn
> 
> ----- Original Message ----- 
> From: "Bob Perkinson" <bobperk@bellsouth.net>
> To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
> Sent: Saturday, December 11, 2004 1:59 PM
> Subject: [FlyRotary] Re: exhaust design question
> 
> 
> > Dennis,
> > I have an AVI file of Tracy running his engine at the rotary round
> > up that I
> > could send you, it is 47 megs worth.  If I knew how to break the
> > file down and shorten it I would do that.  As it is it would take a
> > week to email it.
> >
> > Bob Perkinson
> > Hendersonville, TN.
> > RV9A
> > If Nothing Changes
> > Nothing Changes!
> >
> >
> > I would expect the Renesis engine with the split/side exhaust is not
> > as irritating.  What is the experience?  I have not heard either a
> > 13B or Renesis takeoff or fly-by.
> > Dennis H.
> >
> > Charlie England wrote:
> >
> >> Russell Duffy wrote:
> >>
> >>> So it appears its as much the nature of the Rotary "bark" as it is
> >>> the sound level.
> >>>
> >>>
> >>> I completely agree, and I've tried to get people around the
> >airport>> to understand this.  Since the engine doesn't sound like a
> >"normal">> engine, everyone takes note.  Since they noticed it, they
> >assume it's>> primarily because it must be louder than other engines.
> >  This isn't
> >>> necessarily true of course.
> >>> Glad you got your power back.
> >>> Rusty (yawn)
> >>
> >>
> >>
> >> This phenomenon is widely understood by audiophiles & (ex)sound
> >> engineers. Certain frequencies, and certain harmonic structures
> >added> to any sound, are much more irritating to the ear than others.
> >The> 'bark' or 'edge' in the sound of a 2stroke or rotary is the
> >harmonic> structure of the sound, not the actual level.  I suspect
> >that if you> fed a microphone into an oscilloscope, you'd see
> >something like a sine> or triangle wave from a 4stroke piston engine
> >& something approaching> a square wave from a 2stroke or rotary. We 
> >can run that experiment> here at Slobovia the next time we have a
> >visit from a rotary.>
> >> I suspect that's why Paul Conner's exhaust is actually a pleasing
> >> sound while most rotaries 'hurt' your ears. His iron manifold is
> >> probably filtering out the irritating harmonics & 'rounding off'
> >the> waveform.
> >>
> >> Charlie
> >>
> >>
> >>>>  Homepage:  http://www.flyrotary.com/
> >>>>  Archive:   http://lancaironline.net/lists/flyrotary/List.html
> >>>
> >>
> >
> >>>  Homepage:  http://www.flyrotary.com/
> >>>  Archive:   http://lancaironline.net/lists/flyrotary/List.html
> >
> >
> >>>  Homepage:  http://www.flyrotary.com/
> >>>  Archive:   http://lancaironline.net/lists/flyrotary/List.html
> > 
> 
> 
> >>  Homepage:  http://www.flyrotary.com/
> >>  Archive:   http://lancaironline.net/lists/flyrotary/List.html
> 
> 


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