If composite aircraft were truly composite only and contained no metal
components (or other conductive materials) them lightning strikes would be
much less likely I suspect. Some reports of composite aircraft lightning
strikes (in particular gliders) would suggest it is the metal components
that give rise to a problem.
I remember an accident report roughly 10 years ago when a glider from
Dunstable gliding club flew to close to an area of Cumulo Nimbus activity.
---From memory I seem to recall that one minute the glider was happily
thermalling and the next minute there was an explosion and the occupants
found themselves falling out of the sky along with thousands of pieces of
broken glider. Apart from a broken leg (the instructor landed on the roof of
a petrol station) there were no other physical injuries.
The examination of the wreckage confirmed that the aileron push rods acted
like a massive piece of fuse wire, causing an explosion when the
high-voltage was applied across the tubes. Clearly a case of the current
taking the path of least resistance.
Taking this illustration as an example it would be untrue to say that
aircraft do not attract lightning strikes. As aircraft are inevitably more
conductive than the air in which they are flying they are almost certain to
offer the lightning a path through which to travel. This assumes that there
is a voltage differential from one end of the aircraft the other and
certainly the above report would suggest that this is the case. Also by
virtue of the fact that composite aircraft (in particular) generate an
electrical charge as they pass through the air at high speed they will
attain a voltage potential of their own and again this would attract any
electrical charges in the air through which they are moving.
----- Original Message -----
From: <n3eu@comcast.net>
Subject: Re: Europa-List: Lightning Strikes to Composite Aircraft
>
> > Hi All,
> > According to the AAIB at the last PFA Rally at Kemble, aircraft do not
> > attract lightening, so it will only strike if the aircraft flies
> > through the path of lightening when it is already travelling. This
> > is my understanding of what was said. I therefore try to give CBs a
> > wide birth.
>
> > Regards,
> > William
>
> If that was an exact quote, the AAIB representative may have been winging
it, or "the dog ate his homework." The below research paper is long and
technical, but the first sentence is in plain English: "Not until the 1980's
was it convincingly demonstrated that the vast majority of lightning strikes
to aircraft are initiated by the aircraft, as opposed to the aircraft's
intercepting a discharge in progress."
>
> http://plaza.ufl.edu/rakov/ProgressinAerospaceSciencespaper.pdf
>
> Regards,
> Fred F.
>
>
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