REFLECTOR: No management fuel systems

[nmflyer1 at aol.com]

Dennis, 


 I can only guess as to their position. As you know, mechanical fuel pumps have a cyclic pumping action. That action is usually 1-pumping cycle per rpm. Needless to say, that is not too terribly fast in an aircraft engine. So, what could happen, is that there is not enough pumping suction to overcome an anomaly such as a lost/leaking fuel cap. If the tanks are "T'd" together before a sump, it exaggerates the fuel problems should a cap leak or depart the aircraft. 


In our system, we do not "T" the two tanks together before the sump. Instead we run each tank Into the sump. Makes a difference.  
Then, we have electric pumps that have dozens more pumping cycles per RPM than a strictly mechanical pump. This extra pumping adds more cushion/safety if there were a "gulp" of air or some such. 


All in all, I believe a "stock" velocity fuel system is pretty simple and safe. IF there is a fuel cap leak, it will no doubt show up early and be manageable. If all else fails, we can always land, clean/tighten/lube, and off we go. At least that is the mindset I am taking at this point. 


Press on.. Keep me in the loop, and Have Fun! 


Nice work Dennis, 


Kurt 



-----Original Message-----
From: Dennis Martin <dennis.doc at gmail.com>
To: Velocity Aircraft Owners and Builders list <reflector at tvbf.org>
Sent: Sun, Jan 15, 2012 3:59 pm
Subject: Re: REFLECTOR: No management fuel systems


Kurt,

Any idea why the reference to "mechanical fuel pumps?" I have two Bosch electric pumps - each on a separate circuit for redundancy. Why would it matter that the fuel pump be mechanical?

Before my first flight last week, I put a bit of vaseline on my fuel cap "O" Rings.  I'm adding "FUEL CAPS" to my pre-flight list.

Dennis


On Sat, Jan 14, 2012 at 10:52 AM,  <nmflyer1 at aol.com> wrote:


Interesting thread. Lost a cap in the Cherokee once, didn't do a thing, no fuel lost or feed problems. Must depend on airfoil and placement of the cap. 
Since I lost that thing though, and a replacement cap for a 40+ year old airplane costs a fortune, I have a spare, just in case. I also have spares for the Velocity.
Since we know that the V will most likely lose fuel, or crossfeed, it is pretty cheap insurance to have a spare tucked in the airplane somewhere. The resin ones are very small, and lite. As for the rest of the fuel system, Mine is just as in the plans.... Seems to work quite well for years. 


Kurt .





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-- 
All the best,
Dennis

 
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