nuckolls.bob(at)aeroelect
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 Posted: Sun Jan 10, 2010 11:36 am Post subject: P-Static and Ground Loops? |
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Good Morning Bob
On this forum and another I have been trying to solve a P-static
problem with my glass airplane (not carbon).. It has been suggested
by Chelton and others to run a large (#12) wire and individually
ground the screens, radio stack, AHRS. These have ground wires as
part of the connectors. One of the members on the other forum was
concerned that it would cause a ground loop affecting the
radios. Your opinion?
P-static is a purely external effect on airplanes having
to do with different materials being slid past each other
with some vigor. Like rubbing your cat with a balloon or
shuffling your shoes on synthetic carpet. Machines like
Van de Graff generators can be fabricated with the notion
of optimizing the effects and generating very large
voltages . . .
http://www.coe.ufrj.br/~acmq/electrostatic.html
. . . but still small compared to lighting which
is Mother Nature's own manifestation of P-static.
In the case of p-staic on airplanes, the effect of
flying through particulates (snow, rain, ice crystals,
dust) at high velocities generates a virtual
cloud that produces gazillions of micro-lightning
strikes per second (static). Given that your radios occupy
space within the man-made micro-climate that surrounds
the airplane, the results can make the radios difficult
if not impossible to use.
Unfortunately, there's nothing you can do inside the
airplane to mitigate the effects. Mitigation processes
include:
(1) altering the nature of the materials on
the surface of the airplane to (a) reduce effectiveness
as static generators or (b) make them conductive and/or
(2) add static wicks to effect an orderly, low energy
dissipation of surface charge. If you can turn the
micro-strikes into pico-strikes, the energy in
each strike (electromagnetically radiated noise)
is too small to bother the radios.
When your airplane is decidedly non-conductive,
the task before you is not simple and indeed may
not have a practical implementation. The suggestion
for bonding things together inside the airplane
will not produce a beneficial result.
I don't know if there are any greybeards left
at Hawker-Beech who would remember what we had to
do on the Starship . . . the only ALL COMPOSITE
airplane to be produced at Beech. I'll ask around.
Bob . . .
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