Tony
You have recommended Bob's www.aeroelectric.com recently. I am not able to
get into his web site any longer. Do you know if he is still in business?
I have his book and it probably has a phone number in it. I can try
phoning.
Tom Friedland
"Tony S. Krzyzewski" wrote:
> So a "negative" bus bar, with about a dozen connections, should be
> thrown and replaced with a single point connection for all the "circuit"
> return wires ,as well as a single point connection for the "grounding "
> wires? (Just convince me please that circuit negative wires are the same
> or different to "ground" wires?) Regards Bob
>
> A negative bus bar is a single point ground if all of your
> ground/negative wires terminate on the bar. If all your wiring
> terminates on this single bus bar then you have the best form of ground
> return other than terminating all of the wires at the battery.
>
> The key is to have all the circuit return wires terminate at as few
> (preferably one) point on the aircraft and to have minimal resistance
> (read big fat wire)to the current source return (battery). This single
> point can be a bus bar, a bolt or a plate with connectors. The point
> here is that the resistance between the individual return line
> termination points should be very, very low and a block of brass bus bar
> does this very nicely.
>
> Circuit negative wires are the same as ground wires which are the same
> as return wires.
>
> On a tin can aircraft the skin and structure effectively can act as a
> very large single point ground with the return current flowing over the
> entire skin. As it's a massive area electrically the current flow per sq
> cm is miniscule. Composite aircraft don't have the luxury of having this
> cheap return path so we have to build an individual return path for each
> and every circuit. Unfortunately electricity has the habit of finding
> the easiest path to ground and, if the returns form multiple paths to
> grounds and there is a variation in resistance of those return lines,
> then voltage differences can be induced between the ground points as the
> current flows between them. Bringing all return lines to a single point
> and ensuring that the single point has a low resistance to the aircraft
> true ground point removes the problem.
>
> I have built several large computer controlled model railway systems
> over the years which have amazing parallels to wiring the aircraft.
> Failure to bring the grounds back to a single point in those systems can
> induce so much electrical noise that the microelectronics simply fails
> to work.
>
> Tony
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