Peter, Thanks - absolutely no apologies needed - it is very pertinent! I
had pored over this in great detail when preparing my Oz trip! Both in
this and in the other GRP glider strike quoted the lightning ran from
wing tip to wing tip, with arcing causing enough heating/shock wave to
break open or delaminate the wing. It was very much because of this
report that I hoped to provide a more attractive (both to me and the
lightning) path running essentially outside the wing. Regards, David
On 2014-11-12 16:07, PETER MORGANS wrote:
> Hi David,
> Apologies for diving in on this topic.
> You may be interested to read AAIB Bulletin 12/99 (attached pdf) regarding the
disintegration of Schleicher ASK21 over Dunstable. Back in my gliding days in
the late 1960's it was mandatory for all gliders which held a B.G.A cloud flying
category to have electrical bonding. I think the answer is to stay away from
large Cu unless you have a parachute.
> The following link, ref. this accident, also shows photographs of damage:-
> www.pas.rochester.edu/~cline/.../ASK%20accident%20report.htm
> It's sobering to look at the damage to fittings.
> Regards
> Peter Morgans G-CFKZ Trigear XS
>
> -------------------------
> FROM: "davidjoyce@doctors.org.uk" <davidjoyce@doctors.org.uk>
> TO: europa-list@matronics.com
> SENT: Wednesday, 12 November 2014, 14:00
> SUBJECT: Re: Europa-List: Re: Electrical bonding
>
> Ira, You may well be right and I am quite prepared to accept your superior
> electrical
training, but talking to British Aerospce engineers involved in lightning
protection for the Airbus series did not produce clear answers and my memory
of the Europa lightning strike account is that there were burn marks at each
wing tip and the strike had travelled across the plane. That being the case,
it seems to me to be a better idea to have a path other than the aileron
controls
or wing light wiring to conduct it. Having been in a tram struck by lightning
in my youth and lost a neighbour to a lightning strike, I am not at all
keen to go anywhere near a cu nim, but a large proportion of those flying 'VMC'
---From UK to Australia have been unintentionally caught in electrical storms.
I did not imagine I could make my plane immune to damage but just to lessen the
likelihood of control run welding or instrument burn out.
> Regards, David G-XSDJ
>
> On 2014-11-12 13:17, rampil wrote:
>
>>
>> Bonding together small bits of metal inside a sea of plastic insulator will
>> accomplish nothing except add weight to your airframe unless you
>> have an array of static discharge wicks. No Europas I am aware off have
>> them. The best thing for a builder to do regarding lightning strikes
>> is to make sure there are no voids in the layups where water can infiltrate.
>> The water will turn to steam and explode. Aside from that, Do not
>> fly near Cu. If Cu are unavoidable, just remember: Flying IS avoidable.
>> In this I respectfully disagree with David. As a former electrical engineer,
I would also have to say, I can not see any benefit to bonding wingtip to
>> wingtip, etc. The goal can not be to conduct a strike - you can not! Rather,
>> the goal of bonding to discharge wicks is to bleed off areas of air friction
>> static charge back to the atmosphere, thus avoiding being an attractive
>> nuisance for lightning.
>>
>> There is no such this as "earth" on a composite airplane. The only ground
>> is the negative battery terminal. That's it.
>>
>> It's not a house! There's no neutral (white wire) and earth ground (green
>> wire) dichotomy. Just make all grounds short, fat and tight.
>>
>> --------
>> Ira N224XS
>>
>> Read this topic online here:
>>
>> http://forums.matronics.com/viewtopic.php?p=433500#433500 [1]
>>
>> ectric.com
>> ">www.buildersbooks.com
>> builthelp.com
>> lotstore.com
>> m
>> .matronics.com/contribution
>> ttp://www.matronics.com/Navigator?Europa-List
>> ics.com
>
> www.aeroearget="_blank"
> href="http://www.buildersbooks.com/";>www.buildersbooks.c* My Pilot Store
> www.mrr --> [2]http://www.matronics.com/Navigator?Europa-List [3]=========
Links:
------
[1] http://forums.matronics.com/viewtopic.php?p=433500#433500
[2] http://www.mrel
[3] http://www.matronics.gt;<arel
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