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/
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>
>
>>>  Homepage:  http://www.flyrotary.com/
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> >>  Homepage:  http://www.flyrotary.com/
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