My thought is to take a somewhat different approach to tuning. My desire would be  to tune for intended cruise rpm. My reasoning is that just about all homebuilt designs that will run a rotary will have excess power anyway, so why not tune for max efficiency at the rpm where the the engine will spend 95%+ of its time? Even more applicable if a controllable prop is available.

Can anyone see any problem with that logic?

Charlie

On 11/20/2010 10:18 AM, Mark Steitle wrote:

Ed,

OK, that answers my question.  By going with 1-7/8" OD pipe (.049 wall), it would be tuned for about 7800 rpm.  Obviously, this is too high for our purposes.  I'll go with 1-5/8 (.063 wall) to shoot for 6700 rpm peak power.  This is typically the rpm I see on ground roll and early climb before I start adjusting the prop down to a lower rpm to transition to cruise climb.

Have you used the header designer tool available from Burns Stainless?  You need to know all the timing numbers, rpm, etc.  I may give it a try and see what I come up with.  I have a test p-port housing that I made up to see if the tube could be welded to the inner liner.  So, I can use that with a spare rotor to verify the EVO and EVC numbers.  

 

Mark

On Sat, Nov 20, 2010 at 9:55 AM, Ed Anderson <eanderson@carolina.rr.com> wrote:

Mark,

 

Here is the corrected spreadsheet - I've colored the changeable cells blue - you can plug in any rpm and EVO.  The rest of the cells are protected to keep from accidently overwriting them.

 

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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