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Date: Sat, 30 Apr 2011 10:58:22 -0400
From: Ernest Christley <echristley@att.net>
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To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Re: Timing Question for Tracy
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Lehanover@aol.com wrote:
> On the other hand, the actual clock position of the pickup is not 
> important, so long as the timing wheel relationship with the pickup is 
> maintained. So you can mount the pickup in any location that is handy, 
> and remount the trigger wheel to agree with the pickup location. 
>  
> You do this without moving the crank, and everything remains same/same.
>  

I had to do something in order to add a second VR and second ignition controller. You're telling the computer where the 
crank is and it decides when to send a spark.  It doesn't know where that spark is going, it just sends it when it 
thinks it is time.

So my goal was to have backup ignition.  The problem is that you can't have two VR sensors in the same place, and going 
to one and some sort of splitter circuitry introduces a single point of failure.

My solution was to place the backup VR sensor 185* on the other side of the trigger wheel.  Since the 2nd rotor fires 
180 degrees off from the first, all I have to do is switch the plug wires between the rotors, and I have ignition events 
from independent sources that are placed 5 degrees apart.  The first is controlled by the ECU to modify the advance. 
The second runs off a separate power source.

It is all a game of knowing where the crank is and sending the spark at the right time.