REFLECTOR: Oil lines and ground wire.

[jewen]

Scott,
An aluminum tube 0.5" OD with 0.035" wall will have the same
electrical conductivity as a 10AWG copper wire.  Probably a
bit too low for battery ground.  But, a copper tube of the
same cross section will have the same electrical
conductivity as a 2 AWG copper wire, that may be more
suitable as your ground conductor.  The values were
calculated at standard temp, elevated temps from the oil
will reduce the electrical conductivity, but 2 copper lines
of the listed cross section should be more than adequate at
elevated temps.  You may find the following site usefull for
conductivity values http://www.allmeasures.com/Formulae/

On your hoses, if the are metal braided (especially if
stainless) I would definatley replace them.  They are likely
to be very abrasive to wiring in your conduit.

If you decide to go this route, please recheck my math.  You
may also want to ask Ron Brown, I believed he used a copper
tube for instrument vacuum as well as his ground.

Joe


> My plane came with high pressure hoses for oil lines. Both
> ran in the  pilot side duct.  I noticed that the manual
> calls for 1/2 " aluminum  lines.   I was considering
> replacing the high pressure rubber/steel flex  lines with
> aluminum.  Much lighter and smaller, those hydraulic lines
> are huge and heavy.
>
> I was also considering running one up the pilot side and
> the other down  the copilot side to take advantage of the
> additional cooling benefits.   Has anybody done the
> comparison of running both in one duct and one in  each to
> see if there really is an advantage?
>
> Then I got to thinking about using the oil lines for my
> ground return  path from the battery to the engine?
> Aluminum is a pretty good  conductor, and having two lines
> would seem to provide a substantial  return path if I
> bonded both tubes at both ends?
>
> Anybody do this?
>
> Scott
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