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Date: Fri, 24 Nov 2006 08:26:05 -0700
From: Bob White <rlwhite@comcast.net>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Z-19 questions
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Hi Bill,

I can't help you with Z-19 advise but it's interesting to note the guy
that sent a stupid accidental reply to your question got several
responses.

I already had an airplane that was wired back in the late '70's similar
to some of the certified planes of the day.  Alternator feeds one end
of a bus thru a circuit breaker.  The other end of the bus feeds a
battery thru an ammeter and a battery contactor.  I added a second
battery and a second bus that has everything needed to keep the engine
running, and wired it the same way.  I called this my 'critical' bus.
Both buses are connected to the alternator but isolated with diodes.
The old main bus has the original battery contactor.  The critical bus
has a battery contactor from each battery to the bus so that I can
select one or both batteries to feed the critical bus.  When both
batteries are selected, the batteries are connected in parallel which I
use for starting (two Odyssey PC680's). My theory is that normally,
everything will be running off the main battery.  The second battery is
charged by the alternator, ready to use. If the alternator goes out I
can run off the main battery until it is getting low then switch the
second bus to the fully charged second battery.  I may loose radios,
etc. on the main bus but the engine will still run long enough to get
to the nearest airport.  I used a lot of real estate on my firewall
with battery contactors! :)

I have two fuel pumps plumbed in parallel (Tracy's latest version
with AN fittings on input and output).  I use one big filter which
includes a water separator.  I think Buly mentioned it a while back.
Marvin mentioned one way valves, but these pumps include that
feature.  If some bit of junk came thru the line and blocked the
running pump, then having them in series would loose both pumps.  May
not be likely, but that's my argument for putting them in parallel.
Running one pump I get 45 psi on the fuel rail.  Running two it goes
up to 48 psi. 

Bob W.  


On Fri, 24 Nov 2006 08:45:26 -0500
Bill Bradburry <bbradburry@allvantage.com> wrote:

> 
> OK, This is my fall back position.  I have posed this question on the 
> Aerolectric list for a couple of days and no answer. (although the email 
> did get caught up in an embarrasing event!)  90% of you guys have 
> already wired your planes and followed Bob N's advice, so how did you do 
> the redundancy on the fuel pumps, coils, and injectors?
> 
> from the AE list:
> 
>    "I am installing a fuel injected Mazda rotary engine and trying to follow the Z-19 guidelines for dual battery, single alternator.  Looking at the engine primary and secondary circuit, I need to install a primary and secondary fuel pump, plus I want to power the coils and the injectors 
>     off of the battery buss.
>     How should I do this?  I suppose I could take the fuel pump diode output and switch it to either of the two fuel pumps???
>     What about the coils and injectors?  Should I set up similar circuits 
>     for them, or is there a better way to reduce parts???
>     I would appreciate any guidance you guys could give me.
>     Thanks and Happy Thanksgiving!
>     Bill B
> 
> 
> 
> --
> Homepage:  http://www.flyrotary.com/
> Archive and UnSub:   http://mail.lancaironline.net/lists/flyrotary/


-- 
N93BD - Rotary Powered BD-4 - http://www.bob-white.com
First Flight:  11/23/2006 7:50AM - 0.4 Hours Total Time
Cables for your rotary installation - http://www.roblinphoto.com/shop/