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Date: Sun, 5 Jul 2009 17:27:26 -0600
From: Bob White <bob@bob-white.com>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Re: Below staging
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Still catching up on messages!  This is the last message that I've
found with this heading, and I think I can clear this up a little bit.
This isn't OFFICIAL from Tracy info, but it's what I think is
happening.  Also, for now assume this is all for testing and there
isn't really a problem with the injectors.  Reduces the number of "but
on the other hand's". :)

The EC2 doesn't know whether the injectors have power or not.  It know
two things relevant to this discussion.
1) Is the cold start switch on or off, and 
2) are we above or below the staging point.

If the cold start switch is on, then we should double the gas flow.  

If below staging, we can double flow by turning on the second set of
injectors.  Now if cold start is on because you disabled one or the
other set of injectors, then both sets will be triggering at the same
pulse width as before, but only one of them will have power so gas flow
will be correct.  This is really handy as we don't have to worry about
which set of injectors is turned off since with cold start on all of
them will be working.

If above staging, we would have to double the pulse width to double
gas flow.  Again if one set of injectors is turned off, then you have
1/2 the injectors suppling twice the flow so gas flow is correct for
that situation also.

Of course it doesn't quite work right with different size injectors for
primary and secondary, so a little tweaking of the mixture control is
necessary.

Bob W.  (Only 116 unread messages to go)


On Tue, 30 Jun 2009 13:08:31 -0600
sboese <sboese@uwyo.edu> wrote:

> 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
> 
>  
> 
> 


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