lightning stikes a ASK21

[jeplane]

There is an article in this month of "Business & Commercial Aviation"
regarding lightning.

It says that in 1999, a ASK21 desintegrated large sections of the
fuselage, while flying in clear air, about 800 yards from a cloud.
Both pilots were ejected from the strike, but fortunately were wearing
parachutes.

The same article goes on to say fiberglass, especially carbon fiber is
conductive. So if you are on the ground and a thunderstorm is over the
airport, to seek shelter inside a building and NOT inside the glider
which has no protection.

Has nayone heard this before? Do you know someone who had a lightning
strike in a glider before?
I am just curious as I never heard of this before.

[Vaughn Simon]

"jeplane" > wrote in message
ups.com...
> The same article goes on to say fiberglass, especially carbon fiber is
> conductive. So if you are on the ground and a thunderstorm is over the
> airport, to seek shelter inside a building and NOT inside the glider
> which has no protection.

I have real problems with this statement. Caught in a storm, I would want the
most conductive shell possible around my vulnerable, conductive body. I would
think that an aluminum airframe, being highly conductive, would be perfect.

I thought that the problem with fiberglass was that it was not sufficiently
conductive, which can lead to instantaneous overheating and in-flight structural
destruction.

Vaughn

[David Starer]

I witnessed this accident in which a London Gliding Club K21 was destroyed
in mid-air by what was later found to be an exceptionally powerful lightning
strike. Indeed, the strike was many times more powerful than the most
energetic that commercial aircraft designers typically allow for when
specifying composite components for their aircraft. The pupil, who was a
member of the public on a one day gliding course, parachuted out
successfully, while the instructor suffered minor injuries on landing from
the jump. He was back flying a few weeks later, none the worse for wear, and
continues to fly at the club.

The lightning entered one wing of the glider at roughly the point where the
aileron actuator connects to the aileron, and exited from approximately the
corresponding location on the other wing. The effect was to drive an immense
electrical current though the metal push-rods and other metal fittings in
the fuselage, some of which were vaporised, or else melted and severely
distorted. The effect of this current was to generate a massive amount of
heat which caused the explosive expansion of the air inside the wings. This
stripped the skin off a large part of the wings which, of course, are not
designed to withstand loads that are essentially trying to inflate the wing
from within and peel the skin away from the spar.

The UK Air Accident Investigation Branch took a considerable interest in
this event, not least because a senior investigator happens to be a member
of London Gliding Club and an extremely detailed analysis was published by
them later. This includes a fascinating account of the mechanism of
lightning strikes on aircraft. The UK AAIB report can be found here:
http://www.aaib.dft.gov.uk/cms_resources/dft_avsafety_pdf_500699.pdf. The
accident also attracted the attention of various airlines and aircraft
manufacturers who were interested in the implications for composite
components of commercial airframes.

Contrary to jeplane's quote from Business & Commercial Aviation, the AAIB
report specifically says (in referring to GRP with foam or honeycomb filled
sections bonded together) that "These materials are electrically
non-conductive." Later on it says "In aircraft or gliders constructed from a
non-conducting material such as GRP, the lightning arc is likely to attach
to the extremities of any linked conducting components within that
structure". It was very clear from the AAIB examination of the glider that
it was the electrical conduction through the metal parts, and not through
the skin that caused the aircraft to disintegrate as a result of the events
I have described above.

David Starer

"jeplane" > wrote in message
ups.com...
> There is an article in this month of "Business & Commercial Aviation"
> regarding lightning.
>
> It says that in 1999, a ASK21 desintegrated large sections of the
> fuselage, while flying in clear air, about 800 yards from a cloud.
> Both pilots were ejected from the strike, but fortunately were wearing
> parachutes.
>
> The same article goes on to say fiberglass, especially carbon fiber is
> conductive. So if you are on the ground and a thunderstorm is over the
> airport, to seek shelter inside a building and NOT inside the glider
> which has no protection.
>
> Has nayone heard this before? Do you know someone who had a lightning
> strike in a glider before?
> I am just curious as I never heard of this before.
>

[Mike Lindsay]

In article om>,
jeplane > writes
>There is an article in this month of "Business & Commercial Aviation"
>regarding lightning.
>
>It says that in 1999, a ASK21 desintegrated large sections of the
>fuselage, while flying in clear air, about 800 yards from a cloud.
>Both pilots were ejected from the strike, but fortunately were wearing
>parachutes.
>
>The same article goes on to say fiberglass, especially carbon fiber is
>conductive. So if you are on the ground and a thunderstorm is over the
>airport, to seek shelter inside a building and NOT inside the glider
>which has no protection.
>
>Has nayone heard this before? Do you know someone who had a lightning
>strike in a glider before?
>I am just curious as I never heard of this before.
>
I would have thought that if fibreglass was conductive it would protect
you from the Thunder God. But it isn't, at least not to the extent that
it could carry the heavy current a lightening strike produces without
getting hot enough to disintegrate.

The K21 which was destroyed near the London Gliding Club's Dunstable
site had some control rods which took so much current they more or less
exploded, much like a fuse wire when it takes about 50 times it's rated
load. This explosion blew the skin off the wings.

I once read a book about a glider which fell apart in a Cu-nim in
Germany, the pilot was killed because his parachute carried him up to
even higher levels. But I don't know if this was due to lightening, or
over-stressing the airframe. I believe this happened in about 1928.
I wish I could remember the name of the book and its author, it was what
got me into gliding in the first place.
--
Mike Lindsay

[bagmaker]

we know that GRP (glass fibre) has a low conductivity, is carbon fibre as low?
My understanding was the glues and surrounds of the fibres are the problem, the varios fibres themselves act as a lightglobe type resistor, rapidly heating, then the resins go booooomph.

Any experts?

bagger

[[email protected]]

I live in the lightning capital of the world, Central Florida. I am
not aware of any incidents here but I think we all pretty much give
the old CuNims a wide margin. I have seen bolts strike out and away
from thunderstorm cells by at least several miles. I believe up to 10
miles would not be too rare. If a nasty one was very near at all, I
would get down.
Craig

[nate_fl]

On Apr 14, 5:26 pm, Mike Lindsay > wrote:
> In article om>,
> jeplane > writes
>
> >There is an article in this month of "Business & Commercial Aviation"
> >regarding lightning.
>
> >It says that in 1999, a ASK21 desintegrated large sections of the
> >fuselage, while flying in clear air, about 800 yards from a cloud.
> >Both pilots were ejected from the strike, but fortunately were wearing
> >parachutes.
>
> >The same article goes on to say fiberglass, especially carbon fiber is
> >conductive. So if you are on the ground and a thunderstorm is over the
> >airport, to seek shelter inside a building and NOT inside the glider
> >which has no protection.
>
> >Has nayone heard this before? Do you know someone who had a lightning
> >strike in a glider before?
> >I am just curious as I never heard of this before.
>
> I would have thought that if fibreglass was conductive it would protect
> you from the Thunder God. But it isn't, at least not to the extent that
> it could carry the heavy current a lightening strike produces without
> getting hot enough to disintegrate.
>
> The K21 which was destroyed near the London Gliding Club's Dunstable
> site had some control rods which took so much current they more or less
> exploded, much like a fuse wire when it takes about 50 times it's rated
> load. This explosion blew the skin off the wings.
>
> I once read a book about a glider which fell apart in a Cu-nim in
> Germany, the pilot was killed because his parachute carried him up to
> even higher levels. But I don't know if this was due to lightening, or
> over-stressing the airframe. I believe this happened in about 1928.
> I wish I could remember the name of the book and its author, it was what
> got me into gliding in the first place.
> --
> Mike Lindsay

I too live in Central Florida, where overdevelopment and heavy T-
storms are common during the summer months. The power pilots will tell
you to avoid a convective cloud by 10 miles for every 10,000 ft of
cloud tops. I use a simpler formula, if I can't see the sun because a
cloud is blotting it out I go inside and play X-box.

N

[Tony Verhulst]

The Beech Starship (composite business turbo prop - RIP) had a copper
mesh layer between the layers of fiber glass precisely for lightning
protection. I'm reasonably certain that other like (and larger) aircraft
do too.

Tony V.

[bumper]

"Tony Verhulst" > wrote in message
. ..
>
> The Beech Starship (composite business turbo prop - RIP) had a copper mesh
> layer between the layers of fiber glass precisely for lightning
> protection. I'm reasonably certain that other like (and larger) aircraft
> do too.
>
> Tony V.

That's true. Years ago I saw video of "test" lightning strikes (nowhere near
as strong as the real thing) on unprotected GRP composite material and
composite with mesh, done by either Glasair or Lancair. The difference in
size and impact of the damaged area was dramatic. Without the mesh the hole
in the wing was very big. Without the mesh is was just big. If being zapped,
I'd rather be in an aluminum skinned plane.

I understand that carbon fiber explodes when struck even without metal
control rods to heat up and expand the air within the wing. The carbon does
a fine job of heating and turning moisture into steam

bumper

[Charles Yeates]

Wasn't there a two-place glider in England destroyed in the air by a
lightening strike? I recall control rods in the wing fused and the
fibreglass "exploded" Both aboard succssfully bailed out -- the
passenger was on his first ride but had been briefed. Good thing, eh?

>"Tony Verhulst" > wrote in message
. ..
>
>
>>The Beech Starship (composite business turbo prop - RIP) had a copper mesh
>>layer between the layers of fiber glass precisely for lightning
>>protection. I'm reasonably certain that other like (and larger) aircraft
>>do too.
>>
>>Tony V.
>>
>>
>
>That's true. Years ago I saw video of "test" lightning strikes (nowhere near
>as strong as the real thing) on unprotected GRP composite material and
>composite with mesh, done by either Glasair or Lancair. The difference in
>size and impact of the damaged area was dramatic. Without the mesh the hole
>in the wing was very big. Without the mesh is was just big. If being zapped,
>I'd rather be in an aluminum skinned plane.
>
>I understand that carbon fiber explodes when struck even without metal
>control rods to heat up and expand the air within the wing. The carbon does
>a fine job of heating and turning moisture into steam
>
>bumper
>
>
>
>

--
Charles Yeates
ZS Jezow Agent - PW-6/PW-5

CMYeates & Associates
105 Dunbrack St, Apt 110
Halifax, NS, Canada, B3M 3G7
tel/fax 902.443.0094

Web site http://www3.ns.sympatico.ca/yeatesc/world.html

[Martin Gregorie[_1_]]

bumper wrote:
>
> I understand that carbon fiber explodes when struck even without metal
> control rods to heat up and expand the air within the wing. The carbon does
> a fine job of heating and turning moisture into steam
>
I haven't see a full-size composite aircraft that had a lightening
strike, but I have seen several carbon-structure model aircraft that
landed across power transmission cables. The carbon extracts enough
current from the lines to ignite the epoxy matrix, but doesn't burn
itself. The end result is that the structure is converted to a sort of
tassel of fine, shiny black fibers with no structural integrity or rigidity.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

[Sally W]

At 18:24 15 April 2007, Charles Yeates wrote:
>
>Wasn't there a two-place glider in England destroyed
>in the air by a
>lightening strike? I recall control rods in the wing
>fused and the
>fibreglass 'exploded' Both aboard succssfully bailed
>out -- the
>passenger was on his first ride but had been briefed.
>Good thing, eh?


If you look back through the thread you will find a
link to the AAIB report.

[Bert Willing]

GRP is an insulator. Carbon fiber is a pretty good conductor, but limited by
the resin matrix.

"bagmaker" > wrote in message
...
>
> we know that GRP (glass fibre) has a low conductivity, is carbon fibre
> as low?
> My understanding was the glues and surrounds of the fibres are the
> problem, the varios fibres themselves act as a lightglobe type
> resistor, rapidly heating, then the resins go booooomph.
>
> Any experts?
>
> bagger
>
>
>
>
> --
> bagmaker

[Graeme Cooper]

There is an article in this month of "Business & Commercial Aviation"
regarding lightning.

It says that in 1999, a ASK21 desintegrated large sections of the
fuselage, while flying in clear air, about 800 yards from a cloud.
Both pilots were ejected from the strike, but fortunately were wearing
parachutes.

Has nayone heard this before? Do you know someone who had a lightning
strike in a glider before?
I am just curious as I never heard of this before.

Hi my name is Graeme Cooper and I was the student in the front seat of the glider that day that was destroyed by the lightning. Please visit my justgiving webpage to see what I am planning next! http://www.justgiving.com/big40reachfortheskiesagain
Please help me to raise awareness and funds for the Parkinson's Disease Society by sending the above address to anyone who you think may like to see it and read my story. Thank you

10 years ago I was given a gift certificate from Caroline my Girlfriend (now my wife) for a days gliding at the London Gliding Club to celebrate my 30th Birthday. It was to become a day that I will never forget.

I had been up about 6 times that day in the front seat of a 2-seat glider and was having a fantastic time. Our last flight of the day was coming to an end. We had been flying for about an hour riding the thermals, enjoying the views and I had even taken control of the joystick and pedals on occasions. On the way back to the airfield we noticed a very black cloud off to our right but nothing to worry about.

In a split second everything had changed. I remember talking to the instructor (Peter Goldstraw) when there was a tremendous bang, the plane jolted and it felt as if a missile had hit us. Eyewitnesses say they saw a ball of lightning streak across the sky and hit our glider.

I think I may have been hit on the head by the Perspex canopy getting blown off from its seating as I was confused and was seeing stars. My ears were ringing from the explosion as the force of the blast had perforated both of my eardrums.

Peter was shouting something but it just seemed like mumbling because I couldn’t hear anything. He later explained he was shouting, “get out, get out”!

I quickly realised things were wrong and that we were in serious trouble and that we had to get out of the glider. I was terrified and started shaking, I didn’t dare look down, I looked to the right and noticed that the wing was no longer there. I was thinking of my parents, family and girlfriend and what would they think if I was to die. I had to help myself, there was nothing that Peter could do to control the situation or save us, we were on our own and had to save ourselves. I looked down and managed to twist the buckle on the seatbelt that was holding me into the seat of the glider, stand up and jump free.

Luckily I was wearing a parachute. I found the ripcord and pulled it as I left the glider.

It was a nice feeling to look up and see that the parachute had opened successfully. I looked down and saw that Peters parachute had also opened but that he was quite a way down because I understand he had had trouble opening his chute.

For a moment, I was enjoying the relief of getting out. I looked down and there were bits of wreckage falling. I looked up and there were still bits of wreckage above me, which was worrying as I was scared it might fall and damage the chute.

I saw Peter land heavily in a field and tried to wave to him to let him know I was ok but he wasn’t moving. The GQ parachute that saved me was a round type and not controllable you just go where the wind blows you.

I remember seeing some electricity pylons below and was panicking because I thought I might hit them. Luckily I crossed over them then over a road. I was shouting and waving at people on the ground to let them know that I was still alive as I was coming down.

On the other side of the road there was a disused petrol station. I landed on the roof of it. It was a tin roof that gave a little as I landed.

Although I was on fairly firm ground I was still not out of trouble. I knew that the thing that had saved my life could now put it back in danger. I was strapped into the harness of the parachute with 4 buckles that I quickly undone and threw the harness away from me before the parachute had time to fill with air and drag me off of the roof.

From there I was able to climb down a wall and onto the ground, where some people helped me to calm down. Someone gave me a cup of tea, but most of it went over the floor as I was shaking so much!

Peter and I were taken to hospital in an ambulance where Peter spent a few days recovering from surgery to repair a broken ankle. I was released the same day with just minor scratches, bruises and perforated eardrums.

The wreckage of the glider was taken to the Air Accident Investigation Branch in Farnborough laid out and pieced back together. It was concluded by the investigators and lightning experts that the lightning bolt that stuck the glider was one of the most powerful ever recorded. It was a positive (+) strike the most powerfull type and up to six times the level that even passenger aircraft are designed to tolerate. Six times!

It was whilst waiting in hospital that I began to realise how lucky I had been. I saw a man in a muddy football strip having his leg set in plaster. I thought I have been struck by lightning, fallen from the sky, landed on the roof of a petrol station and still less injured than him.

[Graeme Cooper]

Well I did it. See my scrapbook of the days events of 10 years ago that has just been updated to include photos of my return to the sky:-
http://sites.google.com/site/thebig40reachfortheskiesagain/Home/999glidingpdf1.pdf?attredirects=0

Thanks to all those who supported me in this for your messages of support and donations. You have helped me to help the Parkinson's Disease Society help others. The total raised so far is over £1500!

I will leave you in your aviation world, My feet are safer on the ground!

All the best and

Thank you
Regards

Graeme Cooper

[Graeme Cooper]

Sorry its me again, I have updated my scrapbook to include the TV and radio interviews of my return flight and a film of the reconstruction if you are interested. See :- http://sites.google.com/site/thebig40reachfortheskiesagain/

Bye for now
Graeme Cooper