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Date: Sat, 17 Jul 2004 21:49:34 -0400
From: Ernest Christley <echristley@nc.rr.com>
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To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Re: 11th test flight
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Ed Anderson wrote:
>  Dale,
> 
>     Not being a rotary engine mechanic, I only know that one of things that you were to check for after a case of "overheating" was "shrinkage" of the aluminum rotor housing.  I never heard an explanation for why this supposedly  happened but the thing you were to check for was the width of the housing.  There were minimum specs which if below supposedly rendered the rotor housing "Bad".  I do know that when I took my first engine apart after overheating it to the point that the inner coolant seals failed, I measured and found one of my housings right at the limit - now it may well have been at that point before I ever ran the engine as I did not measure it before hand.
> 
> The only thing I could ever think of that might cause this (assuming it was caused by overheating) is that we have 17 of those big bolts holding that pancake together which compress the rotor housing between the iron housings.  If it go hot enough supposedly that clamping pressure could cause the aluminum to weaken sufficiently to partially collapse the housings coolant chambers and reduce the width of the housing.  But, that was just my take on it.  
> 

That would be a VERY good explanation.  I've had to shorten a couple of 
tubes and bend a few others to get the dimension exactly where I wanted 
them.  You don't want to do it a lot, but... if you heat a piece of 
metal it will expand.  If you don't give it anywhere to go (by locking 
it into one side of a tube for instance), then it will deform, and when 
it eventually cools and shrinks it will pull the surrounding material 
back in with it.


-- 
http://www.ernest.isa-geek.org/
"Ignorance is mankinds normal state,
   alleviated by information and experience."
                                   Veeduber