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From: Dale Rogers <dale.r@cox.net>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Subject: [FlyRotary] Re: rotary risks. MTBE and the gospel ...
Date: Mon, 6 Jun 2005 22:05:16 -0400
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> Al W wrote:>
>  
> > Here's an excellent example. I've seen people describe their 
> > reasoning
> > for going rotary. Often I would hear: "It only has three moving 
> > parts,
> > therefore it's safer". I suspect that 80% of you believed that. That 
> > is a
> > gross error in perspective. No maybe, it's a huge distortion. It's 
> > a
> > wonderful theory, it has a component of truth in it, but totally 
> > fails
> > the tests for significance. 

   I can't agree with you on this one, Al.  Partly, it's not 
the whole story.  In fact, your characterization of the 
premise is, itself, a distortion.  

   Low parts count DOES, indeed, mean fewer things to fail, 
but the simplicity means little if the parts are fragile.
Most renditions mention not only how *few* moving parts 
there are, but also how _robust_ they are.  Compare the 
eccentric shaft with a typical crankshaft: it is massive; 
there are no rod journals to flex.  The rotors are heavier 
than a whole set of pistons, but there are no true reversing 
loads, just a continuous gentle change of vector.  

   It's the *combination* of low parts count AND robust 
parts that made the sale.

Dale R.