REFLECTOR: Oil lines and ground wire.

[Craig and/or Denise Woolston]

John and I used 1/2 thick wall copper tubing for our ground return path.
#2AWG fits inside quite nicely, forming a "pseudo" shielded cable...  Turns
out that std battery post connectors, if the taper is filed off match the OD
of the copper tubing, so we convert to flexible wire at each end using
battery terminals...

Craig


-----Original Message-----
From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of Ron Brown
Sent: Tuesday, September 06, 2005 4:58 AM
To: Velocity Aircraft Owners and Builders list
Subject: Re: REFLECTOR: Oil lines and ground wire.

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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