Sean Dennie wrote:

 Thank you for your time Paul. While not being directly related to the use
of rotaries for aircraft per se, my inquiry deals with the ever present
debate on the true displacement of the engines. I`m sure you have probably
discussed this to great lenghts with everybody under the sun and have your
own beliefs, theories and perhaps a convincing method of conveying those.
As merely a rotary enthusiast, I have not really explored the notion that
the true displacement of the rotary could be anything other than what
Mazda and the SAE calculate it to be. I am now in such a debate myself and
am bombarded by opinions and theories (some of which are convincing) from
other rotary enthusiasts. The problem is that the lack of factual evidence
from a reputable source makes this debate, in my opinion,  a moot point.
Based on the multitude of information you have written of the subject of
the rotay, your many years of experience with them and your close
connections with engineers and other rotary experts, I am hoping you, as a
field expert on the Wankel rotary engine, can shed some light on this
subject.

 The debate centers mostly on the notion that the rotary should be rated
at double the displacement that Mazda and the SAE say it is. Personally I
always agreed (and even argued until I was blue in the face) that this was
the correct method but I am nonetheless open to the idea that it might
not. The general opposition is not even unanimous on what the displacement
should be. Some will argue that it should be doubled and others will
contend that it should be tripled. Then you have motorsports sanctioning
bodies who handicap rotaries based on a factor of 1.5 to one!

 My goal here was to simply get your opinion on the subject. Short of
purchasing the SAE paper on the method of calculating this (SAE paper:
930684 : A Study of the Displacement of a Wankel Rotary Engine) I was
hoping to simply find out if there is any engineering basis for not taking
Mazda and the SAE at their word. I hope I haven`t wasted your time with a
seemingly trivial question from an ignorant enthusiast. All the best to
you and thanks again for your time.

Sean Dennie

No debate! 1.3 Liter two cycle two cylinder equivalent.
Anything further than that is like debating religions.

Paul Lamar
 
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