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Date: Fri, 15 Jun 2007 13:53:05 -0400
From: Ernest Christley <echristley@nc.rr.com>
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To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Re: I've been prayed out of Rotary Purgatory
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Ken Welter wrote:
>> Lehanover@aol.com wrote:
>>> In a message dated 6/15/2007 9:35:51 A.M. Eastern Daylight Time, 
>>> echristley@nc.rr.com writes:
>>>
>>>     One EDIS would be set to control the leading
>>>     plugs with a wasted spark, and the second would control the
>>>     trailing.     It promises to be a very robust setup with 
>>> multiple redundancies.
>>>
>>> Don't forget that the trailing sparks must be distributed. Never 
>>> fired at the same time.
>>>  Because there will be an apex seal between the two spark plugs, and 
>>> destroy the engine.
>>>  Leading plugs in the lost spark situation, is no problem.
>>>  Lynn E. Hanover
>>>
>>
>> That's why two EDIS ignitions are needed...running from separate vr 
>> sensors.  The trailings sensor can even be offset by 5 or 6 degrees 
>> to give the trailing spark delay.
>>
>    Do you know that you can dry fire the leading plugs but you cannot 
> dry fire the trailing they must be only fired on the compression stroke.
>  Ken Welter
Dry fire <=> wasted spark....right?  Again, that's why a second vr 
sensor and EDIS controller is required. 

This scheme adds the complication of a second EDIS, but the second one 
is independant of the first.   Both will run at 10 degrees of advance if 
the computer fails.  Adjust the vr sensor to give another 15 degrees, 
and the engine should fire at the right time even with the controlling 
computer on the fritz.  If the computer and one of the controllers died, 
the remaining controller would continue to provide power...nearly full 
power if the trailing controller, and just partial if the leading.  I 
could see myself switching to the standard spam-can's "left-right-both" 
switch to test the modules.

The computer provides a signal that modifies the advance for idle and 
high revs, but I've paid attention to Lynn.  He's stated several times 
that the rotary will run fine with a static advance of 25 degrees.  So 
loosing the computer would not mean losing ignition.