REFLECTOR: Electrics/Wiring

Terry Miles terrence_miles at hotmail.com
Sun Nov 19 20:41:49 CST 2006


Ronnie,
 
Thanks for that.  You are a great asset to this cyberspace bunch of
builders.  I am thankful we have you around, never failing to answer
questions that have been asked many times over.  As I sit here w/
sodering iron at the ready, I am reminded that besides being a friend,
you are great resouce to have at hand.  I hope to have something to show
in a couple of weeks,but I just re-did my electrical config for the
umteenth time.  
 
I have 2 batts.  Both of equal size.  The plan is to start on DC1, and
have the DC2 power the avionics while in the chocks and be isolated from
engine starts. After start I will parallel them.  I had my charging
wires going out from the B-lug of the alternator to the output side of
each battery's contactor/solenoids.  I see now that starter motor v
surges would be felt on the DC1 charge wire and where it contacts the
DC2 charge wire at the B lug is could be felt by the avionics equipment
even tho the alternator field power was still depowered.  
 
The change is that I've decided to tie the Avionics/Essential bus
directly to the downstream side my DC2 battery contactor in much the
same way as the Main bus is usually tied to the DC1 battery contactor.
I will leave the DC1 charge wire as is and have DC2's charge wire route
from the downstream side of the battery contactor to a common lug with
Avionics Bus distribution wire which will only sence higher alternator
output when I close the tie between Main and Avionic buses.  This would
happen only after the engine is started and stable and the alternator is
placed on line by a separate pilot action.    
 
Now, if I can just figure out which bus to put the annunciator lights on
! 
 
Terry
Wiring XL-RG-5

-----Original Message-----
From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of Ron Brown
Sent: Saturday, November 18, 2006 11:56 AM
To: Velocity Aircraft Owners and Builders list
Subject: Re: REFLECTOR: Electrics/Wiring


I found the Aero Electric information to be extremely helpful. In a
former life, I had lots of experience with electric utility power plant
control and wiring/relay systems, but the wiring info in Aero Electric
was extremely helpful as I designed and wired my Velocity.
 
As I mentioned a couple of months ago, you won't add much weight by
using one size larger wire and adding a few extra spare wires to the
firewall (front and back of the firewall).  Use the keel area for the
stuff in front of the fire wall and reserve the floor ducts for the
engine control cables and engine wiring.  If you are using a vacuum
pump, consider using a 1/2" ID copper tube to double as the vacuum line
and the ground wire to the engine.  Be sure to label the wiring at both
ends to aid in terminating the wires and trouble shooting.  I used
plastic round "canon" twist lock type connectors to enable the
instrument panel to be wired separate from the airplane.  And keep your
wiring diagram to reflect "as built".  Remember, the breakers (or fuses
if you go All Aero Electric), are there to protect the WIRES, not the
end devices. The wire needs to be sized to carry the power (amps)
required by the end device.     
 
An A/I friend of mine uses a wiring board to layout and cut his wiring.
He measures the wiring run lengths from various points in the plane -
like the length of wire from a terminal strip on the fire wall to the
rear duct entrance, length of the duct, length of wire up to the panel,
etc.  Then he marks and lays out the wiring harness on the long work
bench.  Then start pulling the appropriate wires from point to point on
this 2D board.  Of course, you will want to make the wires at the ends
just a bit longer (just-in-case).  Try to avoid running heavy amperage
wiring parallel and close to low voltage signal wiring (temperature and
voltage/resistance sensors.  And COM antenna wiring is probably the
worst noise generator that just loves to change your fuel level
indication when you push the talk button.  So try to keep the COM
antenna wire away from the low voltage stuff.  
 
Have fun!!!!
Ronnie Brown
 
  
 
 
----- Original Message ----- 

From: David Ullman <mailto:ullman at robustdecisions.com>  
To: reflector at tvbf.org 
Sent: Saturday, November 18, 2006 10:00 AM
Subject: REFLECTOR: Electrics


I have been reading Bob Nuckolls' book The AeroElectric Connection.
There is a lot of good detail in this book (see www.aeroelectric.com).
Anyone follow his advice and schematics?  What he says makes sense, but
I have never wired a plane before, so what do I know.  Second, I have
started drawing up a wiring diagram and parts list in Visio.  Anyone
done this who wants to share?

 

Dr. David G. Ullman

Robust Decisions Inc

1655 NW Hillcrest Drive

Corvallis, Oregon, 97330 USA

Phone 541-758-5088

Direct Phone: 541-754-3609

FAX 866-898-1007

ullman at robustdecisions.com

 



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