Jeff,

 

I set up my injector wiring up the same way as you did for the same reasons.  At one time I had the powered side of each set of injectors fitted with a pull down resistor along with a diode to the cold switch.  This would duplicate the action of the optional DPDT switch and worked fine.  At Oskosh several years ago, when I mentioned to Tracy what I had done, he just gave me a strange look and was immediately occupied with another observer.  Although the setup worked, I never pursued the matter further, but removed the resistors and diodes in case something was going on that I didn’t know about.

 

I remember puzzling over how the controller could keep the engine running properly below the staging point with the primary injector power turned off and the cold switch on.  Apparently, the controller looks for a combination of lack of voltage on the injector control wire along with the grounding of the cold switch wire and then takes the appropriate action of using the secondary injectors without a doubled pulse width.

 

Steve Boese

 

 

      

 

-----Original Message-----
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Jeff Whaley
Sent: Tuesday, June 30, 2009 11:50 AM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: Below staging

 

Al, Tracy does not insist that you use the DPDT switches - in the manual they are listed as optional.

I looked at the circuit and concluded that in order to have circuit breakers plus DPDT switches, my parts count was going to double; with panel space at a premium, I bought SPDT switches with built-in circuit breakers.

Also, I thought the chance of an injector failing in flight was pretty remote – as mentioned in the manual.

 

I do test both sets of injectors before flight, but have been doing it above the staging point – PRI:OFF-CS:ON; CS:OFF-PRI:ON … repeat with SEC. This gives you on-the-ground experience of what a bad set of injectors does to your engine plus the effect of what the CS is doing.

I do agree that the DPDT switches would be less awkward but I will leave things as-is for now.

Jeff