RE: Aircraft and lightning

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Ian Darley" <ianhelixsp@xxxxxxx>


There was a case last summer here in the UK of a glider that was 
completely blown apart by lightning. The debris that fell onto the 
ground of melted and vaporized, including the aluminum control rods. 
The pilot and instructor lived! Though suffered hearing damage. Local 
people claimed it was the loudest noise they had ever heard.



<http://www.pas.rochester.edu/~cline/ASK%20lightning%20strike/ASK%20accident%20report.htm>http://www.pas.rochester.edu/~cline/ASK%20lightning%20strike/ASK%20accident%20report.htm







Kind regards







Ian Darley











-----Original Message-----
From: Tesla list [mailto:tesla@xxxxxxxxxx]
Sent: 05 August 2005 07:07
To: tesla@xxxxxxxxxx
Subject: Re: Aircraft and lightning



Original poster: "Gerry  Reynolds" <gerryreynolds@xxxxxxxxxxxxx>



Hi Boris,



There has also been some speculation of the power of a positive

lightning discharge (I've heard estimates of 10x the distructive

power of a "normal" negative discharge).  FAA standards for survival

from a lightning strike are based on the negative discharge.   There

have been several studies of damage from lightning that exceeded ones

that would result from a negative strike. There is also some evidence

that associates the positive lightning stike to the phenomenum of sprites.



Gerry R.





>Original poster: boris petkovic <petkovic7@xxxxxxxxx>

>

>

>Hi All,

>This is bit off topic.Hopefully,Terry will let it go.

>

>Many of You have probably heard of the recent Airbus

>crash in Canada,near Toronto airport.

>It was the accident with happy ending -  miracle that

>all the passangers made it out alive before the flame

>escalation.

>Some investigators speculate the cause of the crash

>was the lightning since heavy thunderstorm was going

>on in the area.

>

>Lightning or not,I'd like to raise few points

>regarding that matter.

>First of all,how lightning initiated by aircraft can

>be the cause of potentialy fatal accidents like

>that?Having in mind that commercial aircrafts are

>designed to be "lightningproof" and rigorous test

>standards for commercial aircraft and aviation

>equipment generally:

>

>http://www.sae.org

>

>Perhaps,situations in reality are way too complicated

>to be imitated by  voltage pulse generators tests-and

>that can sometimes lead to different outcome of the

>process?

>Inspite of huge action integrals ,or specific

>energies, (like 3MJ/ohm) and peak  currents  of 200 kA

>in aircraft test standards,seems that danger is still

>underestimated.How?

>

>Lightning is a multicomponent transient,especially the

>one ignited by a conducting object not attached to the

>Earth.Bidirectional/bipolar leader phase development

>could change triggered lightning pulses  having other

>(unexpected) consequences.

>IIRC,URL to videoframes of a lightning  strike to

>Boeing during take off from an airport in Japan have

>been posted before to TCML,clearly showing upward and

>downward branched leader structures lounched by the

>plane.

>That plane survived the lightning event without damage

>,as well as Apollo 12 spacecraft in 1969. did too.

>But Boeing 747 struck in 1975 near JFK airport (NY)

>and Lockheed jumbo jet near Dallas in 1985. did

>not.Hundreds of passangers got killed.

>

>Quite probably, most of the discharges relating

>lightning  and airborne vehicles go through the stage

>of transient similar to that observed in inital stages

>of so called altitude rocket-triggered lightning.

>The latter has been well studied.It is one of popular

>techniques to trigger lightning  and is employed by

>lightning researches in USA ,France,Japan (rocket and

>wire techniques).

>However,something remains mysterious about lightning

>discharges to flying aircrafts.

>According to eyewitnesses ,they have strange

>properties of being very bright (almost blinding) and

>they produce explosive booms sometimes accompanied by

>sounds reminding of artllery salvos.

>This is not characteristic for usual lightnings.

>IOW,it appears such lightnings often involve large

>charge transfers and very high action integrals.

>Some airborne vehicles lightning accident reports can

>be found in:

>http://plaza.ufl.edu/rakov/ProgressinAerospaceSciencespaper.pdf

>

>To keep this post tesla coil related,it would suffice

>to mention suggestion of some researches to use large

>TC to simulate arc attachment process to an

>aircraft.Energy per pulse,even in the largest TC built

>to date,is way too small  and some other things are

>inadequate  if compared directly with lightning.

>Nevertheless,if employed in connection with set of VP

>generators capable of subsequent discharging under

>control ,powerful TC may find important application in

>HV testing of airborne vehicles.

>The test facility for these purposes would have a

>massive physical size (and great cost of cost).

>On the other hand,constructing of the facility is

>technically viable today I guess.

>Findings relating mechanisms of lightning-aircraft

>interaction may turn to be benefical to the lightning

>protection science.

>

>Comments,suggestions,critics are welcome;

>

>Regards,

>Boris