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Lightning strikes

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Lightning strikes

Old 10th Apr 2006, 09:53
  #41 (permalink)  
 
Join Date: Jun 2001
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If composite structures have not been weather proofed properly nad have absorbed a bit of water, this can be a real problem apparently. The water boils, expands and bursts the structure. This is what may have happened to the 757 radome.
Dan Winterland is offline  
Old 11th Apr 2006, 21:41
  #42 (permalink)  
 
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Location: Montreal
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I heard of a scary incident last week (around April 07) about a Continental flight going into Calgary having been struck by lightning. The FO reported being down to standby instruments only and since the weather in YYC was near minimums, they were asking for help getting up to Edmonton where it was clear.

Has anybody else heard about this incident?
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Old 14th Apr 2006, 16:17
  #43 (permalink)  
 
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lightning strikes

happened to me long time ago ...a loud bang...after landing we discovered that the HF Ant. wa melted off.
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Old 15th Apr 2006, 12:22
  #44 (permalink)  
 
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Dan,

Interesting experience, hope you don't mind me pointing out it is in fact a Faraday cage named after Michael Faraday-he really was a genius.


http://www.rigb.org/rimain/heritage/faradaypage.jsp
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Old 15th Apr 2006, 13:00
  #45 (permalink)  
 
Join Date: Apr 2005
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Devil

I loved reading about all the lightning strikes you guys had, character building I reckon. No mention about brown stains in the underdaks though, and no doubt there's been a few. ha ha ha!! I had a few myself (brown stains and lightning strikes that is) Worst in Dhaka a few years ago but must relate the beauty outta Gatwick one day. The F/o (now Capt) will now know who I am but what the hell. I told him he had no balls for dodging a rather small cell on the radar at low level and then "Kabooomm" , we got whacked. Always maintained that if we'd have flown straight into it we'd been ok, that's my story and I'm sticking to it. Best part was the Fleet Mgr was paxing and it seemed to frighten the crap outta him. Fun Hey ha ha ha ha!!!
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Old 19th Apr 2006, 22:03
  #46 (permalink)  
 
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Got hit going into MEX it was like a speed bump in a lada a bit twitchy but not too bad cc said it was like being hit by a bomb - in the virgin steweradess styleee "Were all going to die" ! ! ! ! ! !
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Old 20th Apr 2006, 10:08
  #47 (permalink)  
 
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A new program in theoretical modeling of the apertureless NSOM data has obtained results based on modeling of the AFM tip, prism surface, and evanescent [email protected] field by discrete electrostatic multipoles, and matching boundary conditions at the respective interfaces with least squares methods. Most importantly, these calculations can be converged for realistic elongated tip shapes that incorporate the lightening rod antenna effect and the actual exponential drop off of the evanescent fields. The results indicate (i) a significant enhancement of the fields near the tip, (ii) a strong sensitivity to the length of the tip elongation, and (iii) a limiting value of the field enhancement of 30 for tip lengths greater than the 1/e evanescent decay. This value is in remarkably good agreement with what is observed experimentally. Furthermore, this analysis indicates a significant contribution to near field enhancement from "image dipoles" generated in the prism when the [email protected] polarized AFM tip approaches within approximately one tip radius (5 nm) of the surface ("Narscissus effect").
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Old 20th Apr 2006, 11:29
  #48 (permalink)  
Warning Toxic!
Disgusted of Tunbridge
 
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Cashking, I think you don't understand that this is not a university forum, it's a practical forum for people who fly (and some nutty people called 'Jetblasters'- they're very weird- don't go there! Might I direct you to 'Agony Aunt' where the assistance you need will be available?). We don't want to go through the mathematics, we actually go into thunderstorms with umbrellas (and aeroplanes) and want to know how not to get hit, not the square root of the urban displacement times the Youngs Modulus x 30 power 'n'!
You are overdazzling us with phony science!
http://www.pprune.org/forums/showthread.php?t=222147

What you are saying is nonsense with defining 'NSOM' and 'K', and what is that garbage about 1/8 evanescent decay?
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Old 21st Apr 2006, 14:52
  #49 (permalink)  
 
Join Date: Apr 2006
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Firstly, let's discuss the specific features of the physico-chemical transformations of the lightning storm air in a wide temperature range. In the lightning storm atmosphere nitrogen oxides, ozone and other "combustible" components start to accumulate reaching concentrations in excess of the normal levels (sometimes by several tent olds). Thus, nitrogen oxide is synthesized through -the following process: (1)
where: the reaction heat effect relates to standard conditions. Having entered the low-temperature zone, is "tempered" [15,16] and can react with oxygen and ozone as in the below equations: (2) (3)
Under the lightning storm conditions the processes described by the cumulative equation of the below type become significant too: (4)
The created dissociates in rain drops and fog particles in the following way: (5)
It should be noted that , also a product of the cumulative process, is similarly unstable even at low temperatures and in the liquid phase decomposes into and . In addition, there are other known processes of the type: (6) (7)increasing the liquid phase conductivity by several orders. The reactions of and decomposition in the gaseous phase under the appropriate conditions can generate some amounts of ions as well.
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Old 22nd Apr 2006, 07:15
  #50 (permalink)  
 
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Cash King seems to have taken to large scale cut and pasting (have just been browsing the magnetic/GPS thread).

Possibly trying to be helpful, but in reality not!
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Old 23rd Apr 2006, 10:24
  #51 (permalink)  
 
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Whatever all that stuff above means, I have no idea. My dear old Mum used to delight in telling the tale of a flight from Geneva to London in a York in the fifties. She was sitting in the first row when she heard a bang and and watched incredulously as a glowing white ball filled the whole fuselage and rolled/moved down the ailse at about the speed of a running man, whatever that might be, and dissapeared out of the tail of the aircraft.
I have no reason to doubt her story, well, she is my Mum, after all.
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Old 23rd Apr 2006, 21:03
  #52 (permalink)  

Coppula eam se non posit acceptera jocularum
 
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Post

Whatever all that stuff above means, I have no idea
Quite simple (says somebody who looked at a probability based method of determining lightning induced damage as a dissertation for my first degree):

1. It is possible to theoretically calculate the propogation of lightning.
2. Lightning fixes free atmospheric nitrogen.

The first is useful in designing structures against lightning strike, but fairly irrelevant here. The second is an important part of our planetary ecosystem but has diddly-squat relevance to those of you at the sharp end pondering the cell in front of you. To be honest, I think CashKing is being a bit of a 'cut n paste intellectual'.
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Old 24th Apr 2006, 02:21
  #53 (permalink)  
 
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hmmm, good stuff! Well here's my little story... Into MAN in a B757, RVR 300 mts in snow, cross wind of 16 kts, so had to brief for an autoland. Comming onto base leg around 4500ft we got hit big time on the nose at night. Saw the whole bolt and strike, its only around 20mm thick!! After making sure my underpants were'nt wet carried on with the app. Next thing I know is the No 1 came in and said "have we just been hit?" I said, yeah, erm, how do you know? she just said " oh just a hunch when a ball of lightning shot down the first 11 rows, then ran out over the wing!"

After landing (good work Mr. Boeing) got to see a 10mm hole in the raydome.

Tend to avoid these days.
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