REFLECTOR: Oil Line Bracket and other stuff.

[Laurence Coen]

Jack,

Let me try to inject some common sense into this discussion.  The oil line bracket is attached to the firewall NOT the engine.  On a spam can the aluminum airframe is attached to the firewall and they seem to last quite a while with out breaking in half and that aluminum isn't near as beefy as the bracket.  The reason a flexible line is used between the engine and the firewall is to prevent the transfer of vibration from the engine.  The engine sits on rubber mounts for the same reason.  As to a steel fitting where the oil line connects to the aluminum rigid tubing a fatigue failure would be the rigid tubing not the fitting.  The bracket is there to prevent that from happening.  The fitting screwed into the engine does need to be steel.

I cut that bracket in half and ran my oil return line down the co-pilot's side and here's why.  Way back when, Wayne Lanza ran some interesting experiments on oil line temperatures while he was still at Velocity.  He measured oil temp. on the outflow and return lines at the firewall and the oil cooler in the nose.  The outflow oil lost 15F on its way to the oil cooler and the return oil increased 10F on the way back to the firewall.  The two lines in the same duct act as a 10 foot long counter flow heat exchanger.  Ten of the 15F outflow drop is heat being transferred to the return oil.  With the same air and oil flow thru the oil cooler the heat transferred to the air is a function of the temperature differential.  Moving the return to the other duct will raise the oil in the cooler 10F thus increasing it's efficiency plus the return oil won't be reheated.   I have a Franklin engine and the factory install kit included a second oil cooler and an under wing ram air scoop neither of which I had to install.

Larry Coen
N136LC


From: Jack Prock 
Sent: Sunday, April 28, 2013 12:25 AM
To: Velocity Aircraft Owners and Builders list 
Subject: REFLECTOR: Oil Line Bracket


Hi,

A bit quiet on the Reflector, so I will throw a question out. My EAA counselor, has suggested that I 
add bracing to the Oil line bracket. He says he thinks that it will be subject to vibration and long term
it will fail.

So, the question is, has anyone had any problems with this bracket? Any fatigue on the bracket
from vibration? My thought is that the oil lines themselves will serve to add stiffness, and the bracket
will not see a large enough vibration amplitude to cause any fatigue... but what do I know, my
plane is not flying yet. So the question is out to those that are.

Jack




--------------------------------------------------------------------------------


_______________________________________________
To change your email address, visit http://www.tvbf.org/mailman/listinfo/reflector

Visit the gallery!  www.tvbf.org/gallery
user:pw = tvbf:jamaicangoose
Check new archives: www.tvbf.org/pipermail
Check old archives: http://www.tvbf.org/archives/velocity/maillist.html
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.tvbf.org/mailman/private/reflector/attachments/20130428/025f1bac/attachment-0001.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image[1].png
Type: image/png
Size: 60863 bytes
Desc: not available
URL: <http://www.tvbf.org/mailman/private/reflector/attachments/20130428/025f1bac/attachment-0001.png>