Peter Zutrauen wrote:
> Not to be argumentative, and altho I agree with Fred that internal
> grounding of the tank may be a bad idea in the case of a
> lightning-strike, plastic planes (without any embedded
> charge-distributing protective mesh) can and do indeed 'explode' when
> hit by lightning anyway - the UK glider as an example.
With one very important difference though. Even beyond the fact the UK
incident involved a monster lightning bolt that is rare:
I takes 2/10 of one thousandth of a Joule to ignite gasoline. The
average lightning bolt has 5 billion Joules! This is why FAA cautions
lightning discharges of a variety we don't consider lightning bolts can
blow up a plastic fuel tank, if it has a way of getting inside.
In the UK incident, the lightning didn't damage the fiberglass
structure, but it was the indirect effects of attachment to control
systems - EMP blast and 50,000F degrees worth of atmospheric
overpressure. In strikes of average strength to composite A/C, the
instances I can find suggests lightning commonly attaches to electrical
systems.
Regards,
Fred F.
|