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SLF3
30th Aug 2007, 19:54
Was SLF on a flight recently that was struck by lightning - on the nose, out through the wing tips.
Does it always hit the nose, and if so why?

Self Loading Freight
30th Aug 2007, 22:20
At the risk of being SLF answering SLF, and basing my answer on stuff I've read, physics I've been taught, plus some experience playing with home-made EHT generators... (in other words, zero appropriate actual experience!)

Electrical discharges to or from a conductor (lightning is either from a charged area to a conductor, which is the case with ground strikes, or from area to area, which is what happens with lightning within clouds) favour the area with the highest potential gradient. That often equates to pointy bits. Aircraft attract lightning when they fly into a zone where a strike is imminent, because (among other factors) they offer a conductive shortcut which pushes local conditions just past the trigger point. The biggest potential difference is normally across the airframe, nose to tail, because that short-circuits the biggest distance, and because those bits are reasonably pointy it enhances the chance that lightning will take that path.

There are plenty of exceptions to that. Lightning may be predictable in the general case, but it's extremely weird strike by strike.

So; yes, it will tend to hit (or exit via) the nose. No, that's not a hard and fast rule. And I am, at best, an enthusiastic amateur in these matters who has utter faith in Faraday cages (although Apollo 12 remains perhaps the most extreme test of such matters).

R

Somph
31st Aug 2007, 11:47
Please excuse my maiden post on PPRUNE... (I've been a long-time lurker, though!)

Faraday cages etc all being well, but how are sensitive electronic instruments protected under these circumstances? This question comes about after some colleagues and I viewed a YouTube snippet on 33KV repair teams using helicpopters to maintain high-voltager lines. :bored:

ClutchingAtStraws
1st Sep 2007, 08:55
Time for me to de-lurk as well!

I was fishing round researching the same question - about effect of lightning strike on avionics - when I came across an article from "Progress in Aerospace Sciences".

Let uncle google do the work using "effect of lightning with airborne vehicles" as the search string, and the article should come out top of the heap.

The article provides some interesting background reading, and should help the approaching winter nights just fly by....