X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from ms-smtp-02.southeast.rr.com ([24.25.9.101] verified) by logan.com (CommuniGate Pro SMTP 5.1.10) with ESMTP id 2204349 for flyrotary@lancaironline.net; Sat, 28 Jul 2007 10:10:05 -0400 Received-SPF: pass receiver=logan.com; client-ip=24.25.9.101; envelope-from=eanderson@carolina.rr.com Received: from edward2 (cpe-024-074-103-061.carolina.res.rr.com [24.74.103.61]) by ms-smtp-02.southeast.rr.com (8.13.6/8.13.6) with SMTP id l6SDNN6i006445 for ; Sat, 28 Jul 2007 09:23:24 -0400 (EDT) Message-ID: <001301c7d11a$8d4d5980$2402a8c0@edward2> From: "Ed Anderson" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: Individual Exhaust Date: Sat, 28 Jul 2007 09:23:56 -0400 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 6.00.2900.3138 X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2900.3138 X-Virus-Scanned: Symantec AntiVirus Scan Engine Bob, while combining exhaust headers of the proper length can provide scavenging - you can also get it with the single headers - self scavenging. The powerful exhaust pulse when it hits the atmosphere (or a larger cross section muffler) returns back up the pipe as a refraction (negative?) wave. If the pipe is of the correct length (rpm dependent among other factors), this refraction wave will reach the exhaust port as it opens and the lesser pressure it causes can help scavenge the combustion chamber. The benefit of mutual scavenging is that the length of tubing to make that happen is shorter (by approx 1/2) than the self scavenging approach. The reason is there is approx 120 rotor degrees between two exhaust port openings on one rotor, whereas there is only approx 60 deg rotor degrees between port opens between the two rotors permitting a shorter tube to get the timing right which is rpm dependent as well as exhaust gas temp dependent. FWIW Ed ----- Original Message ----- From: To: "Rotary motors in aircraft" Sent: Saturday, July 28, 2007 9:03 AM Subject: [FlyRotary] Re: Individual Exhaust > Joe, > > Several people have done just that. The one concern I have is that there > isn't any scavaging > between rotors( one exhaust pulse pulling the exhaust out of the other > rotor). > > Bob > > > ---------------------- Original Message: --------------------- > From: "Joe Ewen" > To: "Rotary motors in aircraft" > Subject: [FlyRotary] Individual Exhaust > Date: Sat, 28 Jul 2007 12:05:18 +0000 > > -- > Homepage: http://www.flyrotary.com/ > Archive and UnSub: > http://mail.lancaironline.net:81/lists/flyrotary/List.html