Return-Path: Received: from ms-smtp-02.southeast.rr.com ([24.93.67.83] verified) by logan.com (CommuniGate Pro SMTP 4.1.3) with ESMTP id 2581974 for flyrotary@lancaironline.net; Tue, 16 Sep 2003 18:41:38 -0400 Received: from o7y6b5 (clt78-020.carolina.rr.com [24.93.78.20]) by ms-smtp-02.southeast.rr.com (8.12.5/8.12.2) with SMTP id h8GMbopN024492 for ; Tue, 16 Sep 2003 18:37:51 -0400 (EDT) Message-ID: <001201c37ca3$69042a60$1702a8c0@WorkGroup> From: "Ed Anderson" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Internal gearing ... Date: Tue, 16 Sep 2003 18:39:37 -0400 MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1106 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 ----- Original Message ----- From: "Canyon" To: "Rotary motors in aircraft" Sent: Tuesday, September 16, 2003 5:22 PM Subject: [FlyRotary] Internal gearing ... > At the risk of exposing my ignorance I have a question. > > There must be a sound reason the internal gearing cannot be adapted to > something more suitable to driving the prop. > > Is it economics or laws of physics or convenience or what which > prevents this happening? > > And yes, I once saw the inside of the rotor housing once about 6 years > ago now. :-) > > Steve > Good question, Steve The short answer is that it would take a complete redesign of the rotary engine. There is a "locked" realtionship between the shape of the rotor (3 surfaces) and the 1:3 gearing between the rotor's gears and the eccentric shafts gears. Each of the 3 rotor faces covers 1/3 of a 360 degree circle or 120 degrees of the circle. The 1:3 gearing means that 120 degrees of rotation of the rotor (one face) causes the eccentric shaft (crankshaft) to rotate 120x3 = 360 degrees. Comes out sort of nice and even that way. More over, the eccentric shaft in turn drives the crank angle sensor (distributor analog) which controlls the firing of the spark plugs. So from the opening of intake and exhaust ports to the firing of the spark plugs, the timing is controlled (and mandated) by the 3:1 gearing relationship between the rotors and eccentric shaft. Also the eccentric shaft lobes causes the rotor to do its "wobulation" at the proper time which if it is off by as little as one gear tooth in syncronization it will cause the rotor to jam agains the rotor housing and lock the engine solid! I am no expert on the rotary and it would appear that you can have different number of faces (not just limited to 3) and that in turn would mandate different gearing to maintain proper timing. On an reciprocating engine you can change the timing of both valves and ignition by changing the camshaft profile, adjustment of the camshaft or shifting the distributor sprocket a tooth or two one way or the other probably without anything drastic happening. Can't change the gearing between rotor and eccentric shaft it by one tooth on the rotary engine that we love and know without locking it solid. So I would say its all three of the factors you mentioned{:>) Hope that helps Ed Anderson