Return-Path: Received: from sccrmhc13.comcast.net ([204.127.202.64] verified) by logan.com (CommuniGate Pro SMTP 4.2.5) with ESMTP id 563475 for flyrotary@lancaironline.net; Sat, 11 Dec 2004 15:08:59 -0500 Received-SPF: none receiver=logan.com; client-ip=204.127.202.64; envelope-from=jesse@jessfarr.com Received: from office5 (pcp04959909pcs.midval01.tn.comcast.net[68.59.199.44]) by comcast.net (sccrmhc13) with SMTP id <20041211200829016007l6kme>; Sat, 11 Dec 2004 20:08:29 +0000 Message-ID: <022001c4dfbd$204a74e0$057ba8c0@farr.com> From: "jesse farr" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: exhaust design question Date: Sat, 11 Dec 2004 15:08:05 -0500 MIME-Version: 1.0 Content-Type: text/plain; format=flowed; charset="iso-8859-1"; reply-type=original Content-Transfer-Encoding: 7bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.2180 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2180 That sounds like one of those 'you just had to be there' sounds, to me. Doesn't someone have a web page with a rotary sound, other than Tracy's flyby ? jofarr, soddy tn ----- Original Message ----- From: "Bob Perkinson" To: "Rotary motors in aircraft" 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 >