REFLECTOR: Oil lines and ground wire.

Ron Brown romott at adelphia.net
Tue Sep 6 07:57:31 CDT 2005


I am using 1/2 ID soft copper water tubing for my 12 vdc ground as well as 
vacuum.  I formed copper tabs from flattened tubing and silver soldered them 
to provide the connections to #2 copper cable.  Has worked just fine for 180 
hours.

Ron

----- Original Message ----- 
From: "jewen" <jewen at comporium.net>
To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
Sent: Sunday, September 04, 2005 12:51 AM
Subject: Re: REFLECTOR: Oil lines and ground wire.


> 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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