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Date: Wed, 11 Aug 2004 21:14:10 -0400
From: Mike Robert <pmrobert@bellsouth.net>
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To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Re: Pressure switch
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Russell Duffy wrote:

> In fact, I just realized why I run so rough on desent.  The MAP is 
> probably getting pulled down below 10" and the pressure probably drops 
> even more making it very lean...  hmmm  :-)
>
> I mentioned this to Tracy one day, and he said (best I understood it) 
> that the engine basically isn't running under these conditions.  For 
> one thing, the injector duty cycle is so low that they effectively 
> aren't opening.  I've noticed times in the pattern when I was 
> descending at idle, and the engine noise seemed to almost go away.  
> Opening the throttle some made it start, then going to idle stop.  I 
> got the distinct feeling that the engine was not running at idle, just 
> like a car cuts the fuel on deceleration.  Interesting. 
>
> Rusty (Maaaaaaaayby running Rev-3 by Sunday)
>
>
If you're running only premix, be careful with this situation, for 
obvious reasons. Those apex seals *like* a touch of lubrication :-) Pump 
people should be fine! I run premix in my daily driver rotary and set 
the ECU to give .3 ms + opening time to my injectors on overrun/decel - 
which is what descending at idle is, to an extreme, for a long time. Ed, 
still haven't got into that attic for the SAE paper, my apologies! I'll 
be up there soon.


      -Mike