Message-ID: <38B949BD.168E3BFF@regandesigns.com>
Date: Sun, 27 Feb 2000 09:58:53 -0600
From: Brent Regan <brent@regandesigns.com>
To: Skip Slater <skipslater@earthlink.net>,
        Lancair List <lancair.list@olsusa.com>
Subject: Re: Electrical bonding for static buildup
References: <000c01bf8142$8e26df00$464e1d26@computername>
Mime-Version: 1.0

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Here is an e-mail exchange Skip and I had that the group may find interesting.


> >Skip Slater wrote:
> >
> >> Brent,
> >>    Interesting that this static topic came up right after I asked you on
> the
> >> phone about the need for static wicks on my ES project.  Since it is a
> >> mostly non-conductive airframe, what would your recommendation be for (1)
> >> the need for static wicks and (2) how best to make a grounding point for
> >> fueling and where you think it ought to be located.
> >>    The breadth of your knowledge never ceases to amaze me.  I hope my
> >> incessant brain picking isn't a bother, but I can't begin to tell you how
> >> much valuable information I've gleaned from talking with you.  I also
> can't
> >> tell you how much I appreciate your time and patience with what must
> surely
> >> seem to be some very rudimentary questions.  I'm learning fast.
> >>    Best regards,  Skip Slater

Brent Regan wrote:

>Skip:
>
>The only thing that can accumulate a charge and drain it is the electrical
>system and grounded metal parts (engine, landing gear, pushrods etc). Be
sure
>everything is bonded together with wire or copper foil tape and to the
static
>wicks. Gary Burns had two metal fins (one on each wing) sticking up and
labeled
>"GROUND HERE", but grounding to the landing gear would be fine too.
>
>If it looks like your fuel probe is close to your filler than I would
probably
>ground your fuel ring as well.
>
>Brent


Skip Slater wrote:

> Thanks for the advice Brent,
>    One more question though.  When we spoke on the phone about this, I
> thought you said that the nose (cowling) could be the source of a lot of
> static even though it was composite.  The note below seems to say that it
> can't because it's not conductive.  I'm just wondering if I should bond any
> copper tape to the inside of the cowling as I believe you told me you did
> with yours.
>    Thanks again,  Skip

Brent Regan wrote:

> Yes, that was to reduce P-stat and it's associated radio interferance. When a
> local charge builds to the point that the surrounding air dielectric is
> insufficient, then the air becomes the conductor and the charge quickly
> dissapates into the air. The resulting current produces a broadband EM pulse
> (like a Marconi transmitter) that interfeers with the COM and NAV radios.
> Carbon reinforcements around the air inlets with copper tape to drain off the
> charge to the static wicks will help. The reason static wicks work is the
> large number of sharp points on the ends. Electrons tend to pile up on points
> (a molecular version of surface tension, sort of) and leap off into the air in
> a steady flow, reducing the noisey current pulses.

Fred once pointed out to me the lines of little metal diamonds seen on most jet
radomes. They provide a path for the charge by letting the charge leapfrog from
one diamond to the next without presenting a solid conductor to block the radar
antenna behind it.

> Brent
>

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