REFLECTOR: "Rube Goldberg" reisitor for plastic airplane fuel systems

[Ron Brown]

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" <Dastaten at earthlink.net>
To: "Velocity Aircraft Owners and Builders list" <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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