REFLECTOR: "Rube Goldberg" resistor for plastic airplane fuelsystems

[Lawrence Epstein,MD]

Good answer! Thanks for the explanation/reference. Just another example
of something that seems logical, can be backwards if you don't know all
the details.
 
Larry E.
 
-----Original Message-----
From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of Ron Brown
Sent: Monday, July 02, 2007 12:03 PM
To: Velocity Aircraft Owners and Builders list
Subject: Re: REFLECTOR: "Rube Goldberg" reisitor for plastic airplane
fuelsystems
 
Brother Dave,
 
This "rube goldberg" resistor is a development and suggestion by the
Rube Goldberg aircraft division called the CAFE Foundation, documented
in Sport Aviation, March 2001, excellent article on fuel systems for
plastic airplanes starts on page 35, the specific recommendation is on
page 40.
 
I consider this a must read about plastic airplanes and their fuel
systems.
 
Quoting from the article "Using proper mounting techniques, route the
(ground) wire into the cockpit and connect it to the ground bus through
a resistor (approximately 1 meg ohm, 1 watt). The resistor limits the
power of any static discharge by"spreading out" the discharge time,
which turns the discharge arc to a corona-like discharge that is less
likely to ignite the gas fumes. 
 
"In any case, when fueling it is good practice to keep the nozzle in
contact with the filler neck. If both the filler neck and the nozzle are
grounded, there should be no problem. But you can't be too sure about
some gas hoses and nozzles or ground connections to an airplane from the
truck or pump." 
 
However, if you touch the metal fuel nozzle to the fuel tank ring and
there IS a static potential, there is a good chance of a spark and a
small to very large poof as the fuel in the tank ignites.
 
After hearing about a brand new Velocity, belonging to Melvin Ball in
Montrose in Colorado that burned to the ground during a refueling
accident (no details available - I have enquired - Mr. Ball didn't want
to discuss).
 
Not trying to be a smart A_ _, just trying to better educate the
experimental aircraft building community.  
 
Ronnie Brown
EAA Technical Counselor
EAA Flight Advisor 
350 Educational Hours in a Velocity - and thousands of hours researching
and learning while building! 
 
----- Original Message ----- 
From: "David Staten" < <mailto:Dastaten at earthlink.net>
Dastaten at earthlink.net>
To: "Velocity Aircraft Owners and Builders list" <
<mailto:reflector at tvbf.org> reflector at tvbf.org>
Sent: Monday, July 02, 2007 2:10 AM
Subject: Re: REFLECTOR: Fuel venting issue
 
> If you connect the airframe ground to the truck, then there is no need

> for any kind of rube goldberg resistor. The airframe and the fuel
truck 
> are iso-electric at this point. Then.. for good measure, connect the
two 
> (truck and plane) to a grounding rod in the pavement or a tiedown.
> 
> Our velocity has grounded caps, with the ground wires connected to 
> airframe ground. No resistors.
> 
> Dave
> 
>>"I also connected a ground wire from this vent line and it connects to
the 
>>filler cap. These vent lines are grounded through a 100 Kohm resistor
to 
>>ship ground. This reduces the amount of spark that would be generated
if 
>>there was a static charge difference between the fuel hose and the
filler 
>>caps."
>>
> 
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