REFLECTOR: "Rube Goldberg" resistor forplasticairplanefuelsystems

Mon Jul 9 17:32:02 CDT 2007

This is similar to my answer.

A small piece of chain with a hook on it fits inside the gas filler
ring.  This chain is covered by a thin flexible piece of plastic tubing
from the hardware store.  The grounding clamp from the truck is attached
to the chain.  This 1 ft piece of delicate chain fits fine in the strake
shelf at the door.  The plastic tubing protects my paint and the hook
keeps the chain inside the filler ring grounding the ring to the chain
to the truck ground wire.  A small piece of clothes hanger wire with
shrink wrap about three inches from the hook keeps the chain from ever
falling into the tank if the grounding wire clamp pops off.  Can't say I
always use it but makes me feel like I'm trying.  Otherwise I touch the
filler ring with one finger and the other hand to the ground.  I do not
know my resistance but seemed reasonable at the time.

Rene'

-----Original Message-----
From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of Lou Stedman
Sent: Friday, July 06, 2007 7:40 AM
To: Velocity Aircraft Owners and Builders list
Subject: Re: REFLECTOR: "Rube Goldberg" resistor
forplasticairplanefuelsystems

If you are looking for an easy to ground for fueling, take a page from
the Long EZ group. I did this on my Long and my Velocity. Get some piano
wire, cut off about 8", bend a loop in the center. Now get yourself some
stainless light pull chain. Using safety wire, attach the safety wire to
the nut on the bottom or your gas cap. Then twist about 8" and attach it
to the piano wire at the loop and to that attach about 18" of the
stainless pull chain. Now insert the chain into your fuel tank. Turn the
piano wire vertically and put it through the hole as well. You now have
a safety stop for your fuel cap if it ever comes loose in flight and a
grounding point for the fuel ground.

Lou Stedman
Velocity N7044Q
Olean, NY

----- Original Message ----- 

From: Douglas Holub <mailto:doug.holub at tx.rr.com>  

To: Velocity Aircraft <mailto:reflector at tvbf.org>  Owners and Builders
list 

Sent: Thursday, July 05, 2007 11:15 PM

Subject: Re: REFLECTOR: "Rube Goldberg" resistor for
plasticairplanefuelsystems

I think the author of that Sport Aviation article must have gotten
something confused. 

If there was a 100k resistor attached to the aluminum fuel tank filler
ring, and if the fuel truck nozzle touched that resistor first instead
of the filler ring, there wouldn't be a spark. 

And if there was a place on the airframe designed for the fuel truck's
grounding cable clamp, and if that place was connected to ship's ground,
and if the ship's fuel tank filler ring was attached to ship's ground
through a 100k resistor, then there wouldn't be a spark when the fuel
truck's grounding cable clamped on to the airframe. But so what? That
clamping location shouldn't be anywhere near any fuel vapors. 

Someone on the AeroElectric list asked Bob Nuckols this question. He
answered:

When a fueler walks up to a Sundowner and puts the nozzle into
    the tank, the electrical connection between the fuel truck ground
    and the rim of the filler neck is pretty low resistance. I can't
    think of any good reason to make that something different for
    a plastic airplane.

      Bob . . .

----- Original Message ----- 

From: Lawrence <mailto:ljepstein at hotmail.com>  Epstein,MD 

To: 'Velocity Aircraft <mailto:reflector at tvbf.org>  Owners and Builders
list' 

Sent: Monday, July 02, 2007 2:07 PM

Subject: Re: REFLECTOR: "Rube Goldberg" resistor for plastic
airplanefuelsystems

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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