flyrotary@lancaironline.net Mailing List Archive

Ed,

Now I've got you doing it. I have always been suspicious of applying formulas to the rotary that were derived from 4-stroke piston engines. The fact that the rotary book suggests exhaust tube lengths of between 10 and 18" confirms my suspicions. Also, a 15" tube should be much easier to fit under the cowl. There may even be room for a muffler if I plan carefully. I appreciate you putting the spreadsheet together so us non-engineering types can understand this stuff.

Mark

On Sun, Nov 21, 2010 at 7:53 AM, Ed Anderson <eanderson@carolina.rr.com> wrote:

Mark,

I did some additional reading in the rotary book I recommended to you and a bit more head scratching on exhaust systems.

I modified the tube length formula I used earlier to compensate for the fact the rotary puts out two exhaust pulses per port per 720 deg cycle compared to 1 for the piston engine. This in effect halved the length of tube needed to get the same scavenging effect.

Also using the recommended rotary book values for area of a rotary exhaust tube , I calculated the tube diameter which came out to 1.8".

In any case, I have attached the spreadsheet with those modifications

Ed

Edward L. Anderson
Anderson Electronic Enterprises LLC
305 Reefton Road
Weddington, NC 28104
http://www.andersonee.com
http://www.eicommander.com

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