Rocket-triggered lightning

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JImbo Franz

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Apr 3, 1998, 3:00:00 AM4/3/98
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Daniel Wilkes wrote:

> Wouldn't you have to use a fairly heavy wire on the rocket or...*poof*
> instant copper vapour ?

It vaporizes anyway, and the lightning follows the ionized trail.

--
Jimbo - Renegade Intellectual
Attaching the electrodes of knowledge to the nipples of ignorance.
The trouble with good ideas is that they soon degenerate into a lot of hard
work.
The advantage of the emotions is that they lead us astray.

Perspective is everything

Daniel Wilkes

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Apr 4, 1998, 3:00:00 AM4/4/98
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hgef...@mdcisjf.org wrote:

> A lightning discharge is free to anyone who provides the conductive
> path of least resistance, and releases more energy than most homemade
> bombs.
>
> Am curious of the effect of launching a model rocket, trailing thin
> wire from a grounded (connected to earth) spool. Can try in an empty
> open field but curious if this has been tried, though
>
> Is there any law against experiments with lightning, other than
> Darwin's theory which comes in to play if the experimenter is anywhere
> near his apparatus?
>
> Feel the wrath of Thor's mighty hammer!
>

Wouldn't you have to use a fairly heavy wire on the rocket or...*poof*
instant copper vapour ?

Dan.

Michael Martucci

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Apr 4, 1998, 3:00:00 AM4/4/98
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I've seen this done on tv. But the triggering is done by blowing on a
plastic tube, from an insulated cabin. And even so they need all this
hightech equipment to detect regions of the cloud that have a strong
charge.

This was for testing lighting conductors, which were placed nearby the
launch pad.
A thin wire will provide a path for the downstroke, but the "hole" punched
in the atmosphere by the downstroke provides a low resistance path for the
upstroke, the part you see in a lightning bolt.

Some more knowledeable in this area may be able to correct and/or
elaborate on what I've said.


In article <3525C428...@ihug.co.nz>, Daniel Wilkes
<dwi...@ihug.co.nz> wrote:

--
"As long as you don't know your future, you can control your future"
Michael Martucci
mart...@picknowl.com.dot-au
(Replace .dot-au with .au)

Roger Riordan

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Apr 4, 1998, 3:00:00 AM4/4/98
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hgef...@mdcisjf.org wrote:

>A lightning discharge is free to anyone who provides the conductive
>path of least resistance, and releases more energy than most homemade
>bombs.
>
>Am curious of the effect of launching a model rocket, trailing thin
>wire from a grounded (connected to earth) spool. Can try in an empty
>open field but curious if this has been tried, though

This, very roughly, was what Benjamin Franklin did. He was lucky; his
string was a poor conductor, so he survived. Someone who tried to
duplicate the experiment shortly afterwards didn't. Recent TV show
on lightning showed a research station in the European Alps where they
do exactly this. They wait till a storm is overhead, observe the
frequency of flashes, then shortly before the next flash is due, fire
a rocket trailing a wire. Gave the impression they can fairly
consistently trigger a full power stroke.

Don't suggest you try this; lightning is perhaps even more dangerous
than explosives. You can be killed by the potential difference
between your feet at a moderate distance from the direct stroke. If
you do want to try it you need to be in a well built faraday cage, and
you need something clever to fire the rocket. You don't want to have
wires running back to your cage, or they'll bring the lightning right
in.


Roger Riordan

Roger Riordan

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Apr 4, 1998, 3:00:00 AM4/4/98
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Daniel Wilkes <dwi...@ihug.co.nz> wrote:

>hgef...@mdcisjf.org wrote:
>
>> A lightning discharge is free to anyone who provides the conductive
>> path of least resistance, and releases more energy than most homemade
>> bombs.
>>
>> Am curious of the effect of launching a model rocket, trailing thin
>> wire from a grounded (connected to earth) spool. Can try in an empty
>> open field but curious if this has been tried, though

>Wouldn't you have to use a fairly heavy wire on the rocket or...*poof*
>instant copper vapour ?

If you use a fairly heavy wire, you'll still have instant copper
vapour. :-) The wire doesn't have to be thick; it just has to provide
a conductive path to guide the leader stroke. Indeed I'm not at all
sure if you need it at all. The rocket trail would be fairly well
ionised, and if you chose the right moment this could well be enough
to trigger, and channel, the strike.


Roger Riordan

Seth

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Apr 4, 1998, 3:00:00 AM4/4/98
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Roger Riordan wrote:
>
> hgef...@mdcisjf.org wrote:
>
> >A lightning discharge is free to anyone who provides the conductive
> >path of least resistance, and releases more energy than most homemade
> >bombs.
> >
> >Am curious of the effect of launching a model rocket, trailing thin
> >wire from a grounded (connected to earth) spool. Can try in an empty
> >open field but curious if this has been tried, though
>
> This, very roughly, was what Benjamin Franklin did. He was lucky; his
> string was a poor conductor, so he survived. Someone who tried to
> duplicate the experiment shortly afterwards didn't. Recent TV show
> on lightning showed a research station in the European Alps where they
> do exactly this. They wait till a storm is overhead, observe the
> frequency of flashes, then shortly before the next flash is due, fire
> a rocket trailing a wire. Gave the impression they can fairly
> consistently trigger a full power stroke.
>
> Don't suggest you try this; lightning is perhaps even more dangerous
> than explosives. You can be killed by the potential difference
> between your feet at a moderate distance from the direct stroke. If
> you do want to try it you need to be in a well built faraday cage, and
> you need something clever to fire the rocket. You don't want to have
> wires running back to your cage, or they'll bring the lightning right
> in.
>
> Roger Riordan

Actually, lightning NEVER struck Ben's kite. He simply collected
electrical charges from the storm.

Probably one of history's greatest myths...:)

-Seth Ridley

David Richards

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Apr 4, 1998, 3:00:00 AM4/4/98
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I've asked about this in rec.pyro a year or so ago, the consensus was that
is possible, but hitting the right cloud is tricky. The hardest part is
firing the rocket at the right moment, yet not giving the lightning a path
from the launcher to you.

In article <3528b9d4.7878630@wingate>, <hgef...@mdcisjf.org> wrote:
>A lightning discharge is free to anyone who provides the conductive
>path of least resistance, and releases more energy than most homemade
>bombs.
>
>Am curious of the effect of launching a model rocket, trailing thin
>wire from a grounded (connected to earth) spool. Can try in an empty
>open field but curious if this has been tried, though

You should be able to do it without needing a wire, the rocket exhaust
trail may be sufficient (especially if you're using a zinc-based solid fuel)
or perhaps a zinc+sulfur smoke device on the side of the rocket.

>Is there any law against experiments with lightning, other than
>Darwin's theory which comes in to play if the experimenter is anywhere
>near his apparatus?

There are regulations on flying rockets into cloud cover.


David Richards

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Apr 4, 1998, 3:00:00 AM4/4/98
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In article <35266e81.4778100@wingate>, <gsd7...@7gdsefeg.com> wrote:
>On Sat, 04 Apr 1998 11:00:19 GMT, rio...@werple.net.au (Roger
>Riordan) wrote:

>>hgef...@mdcisjf.org wrote:
>>Don't suggest you try this; lightning is perhaps even more dangerous
>>than explosives. You can be killed by the potential difference
>>between your feet at a moderate distance from the direct stroke. If
>>you do want to try it you need to be in a well built faraday cage, and
>>you need something clever to fire the rocket. You don't want to have
>>wires running back to your cage, or they'll bring the lightning right in.

>A direct connection to the launch pad would be suicidal. How would RF
>control work in such a hostile (wet, electrical noise from other
>flashes as detected on AM radio) environment...and for safety, a
>secondary fixed length mechanical delay timer that would start as soon
>as the RF signal was detected...or fiber optic line.

I wonder if perhaps the localized rise in static charge itself could be
used to trigger the rocket?

Put the launcher out in an huge open field, where your lightning rod is
the highest pointy object for miles around. The equipment can automatically
measure the charge on your rod, and when it's sufficient to sustain a strike,
fire the rocket to provide a path.

Totally automated, no need to be anywhere near the danger zone.


>Or maybe since lightning damage to electrical & communication lines is
>a big problem, there are govt grants available to buy the proper
>equipment & make a living while doing the tests, beats flipping burgers!

Assuming you can get university backing to make your grant proposal
likely to be accepted, go for it.

ma...@freenet.edmonton.ab.ca

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Apr 5, 1998, 4:00:00 AM4/5/98
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NASA does this. The rocket has a cone shaped spool on the bottom with a
thin brass wire. They wait until a thunder storm is overhead and fire the
rocket by remote control. By timing the frames on the video and
estimating the distance travelled between frames I would say the rocket
got to about 500 feet before the lightnign hit. The ground end of the
wire should be solidly grounded and you should be in a metal building.
My pyro buddy and I have been talking of doing this for years.

Mark Waluk


hgef...@mdcisjf.org wrote:
: A lightning discharge is free to anyone who provides the conductive
: path of least resistance, and releases more energy than most homemade
: bombs.

: Am curious of the effect of launching a model rocket, trailing thin
: wire from a grounded (connected to earth) spool. Can try in an empty
: open field but curious if this has been tried, though

: Is there any law against experiments with lightning, other than


: Darwin's theory which comes in to play if the experimenter is anywhere
: near his apparatus?

: Feel the wrath of Thor's mighty hammer!

: Dont try this at home kids.

: http://www.fpc.com/pqpage/natural/video.htm
: http://www.atmo.arizona.edu/research6.html
: http://www.wvinter.net/~daniel/lightning/faq.html

--


Jerry L. Golden

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Apr 5, 1998, 4:00:00 AM4/5/98
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>I've seen this done on tv. But the triggering is done by blowing on a
>plastic tube, from an insulated cabin. And even so they need all this
>hightech equipment to detect regions of the cloud that have a strong
>charge.

The Discovery channel I think. The show was about lightning
research and the lab that had the rockets was in Arizona or New Mexico
(?). The tube was a safety measure needed because lightning would
induce a heck of a pulse into plain Cu wire. The cabin was shielded
because it wasn't too far away from the lightning stroke path.

>
>This was for testing lighting conductors, which were placed nearby the
>launch pad.
>A thin wire will provide a path for the downstroke, but the "hole" punched
>in the atmosphere by the downstroke provides a low resistance path for the
>upstroke, the part you see in a lightning bolt.

The models they used appeared to be plastic that were specificaly made
for them (I suppose you could find them somewhere if you wanted to).
The wire vaporized instantly, but once the ionized channel was formed
it wasn't needed anymore.
Perhaps the original use for the rockets were for throwing a
'starting' line on coastal rescue applications (30 # fishing line ?).


>
>Some more knowledeable in this area may be able to correct and/or
>elaborate on what I've said.
>

I'm primarily into the rocket part of it. It would make my hobby a bit
easier; fire it off, reel it in. Fire it off, reel it in. Ect. (Hmmm.
Maybe we're on to something here...)

remove the spam.
"spammers are killing all this"

David Keil

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Apr 5, 1998, 4:00:00 AM4/5/98
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Scott Pankhurst added:

>
> hgef...@mdcisjf.org wrote:
> >
> > Feel the wrath of Thor's mighty hammer!
> >
> > Dont try this at home kids.
>
> Er.... may I suggest radio/IR triggering of the rocket, as opposed to
> conventional wires?

Just to follow the thought. You could use a time delay as well. there
is a simple cheep curcuit for a 2 minute delay using a 555 and arelay in
this months Electronics Now.

cheers.

DNK!


Scott Pankhurst

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Apr 6, 1998, 3:00:00 AM4/6/98
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Daniel Wilkes wrote:

> hgef...@mdcisjf.org wrote:
>
> > A lightning discharge is free to anyone who provides the conductive
> > path of least resistance, and releases more energy than most
> homemade
> > bombs.
> >
> > Am curious of the effect of launching a model rocket, trailing thin
> > wire from a grounded (connected to earth) spool. Can try in an empty
>
> > open field but curious if this has been tried, though
> >
> > Is there any law against experiments with lightning, other than
> > Darwin's theory which comes in to play if the experimenter is
> anywhere
> > near his apparatus?
> >

> > Feel the wrath of Thor's mighty hammer!
> >
>

> Wouldn't you have to use a fairly heavy wire on the rocket or...*poof*
>
> instant copper vapour ?
>

> Dan.

I know of no wire available that would withstand the current flow
delivered by a lightning strike... at least not that any rocket other
than an STS could carry! But, all it needs to do is provide an initial
pathway of least resistance, and the lightning will continue to use the
`hole' for the rest of the arc.

Scott Pankhurst

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Apr 6, 1998, 3:00:00 AM4/6/98
to

hgef...@mdcisjf.org wrote:

> A lightning discharge is free to anyone who provides the conductive
> path of least resistance, and releases more energy than most homemade
> bombs.
>
> Am curious of the effect of launching a model rocket, trailing thin
> wire from a grounded (connected to earth) spool. Can try in an empty
> open field but curious if this has been tried, though
>
> Is there any law against experiments with lightning, other than
> Darwin's theory which comes in to play if the experimenter is anywhere
>
> near his apparatus?
>
> Feel the wrath of Thor's mighty hammer!
>

Daniel Wilkes

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Apr 6, 1998, 3:00:00 AM4/6/98
to


JImbo Franz wrote:

> Daniel Wilkes wrote:
>
> > Wouldn't you have to use a fairly heavy wire on the rocket or...*poof*
> > instant copper vapour ?
>

> It vaporizes anyway, and the lightning follows the ionized trail.
>

Yeah, I thought of that as soon as I sent the last message.

Dan.

Michael J Edelman

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Apr 8, 1998, 3:00:00 AM4/8/98
to


Daniel Wilkes wrote:

> Wouldn't you have to use a fairly heavy wire on the rocket or...*poof*
> instant copper vapour ?
>
>

Copper vapor is just as conductive as copper wire! And after the first
strike, of course, you have an ionized path that will conduct the following
strikes. Only a fine wire is needed to initiate the first strike.

If you wanted a wire heavy enough to conduct a strike without melting, you'd
have to pull a piece of copper bus a few feet in diameter.


-


Michael J Edelman

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Apr 8, 1998, 3:00:00 AM4/8/98
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Daniel Wilkes

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Apr 9, 1998, 3:00:00 AM4/9/98
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Michael J Edelman wrote:

Are the lightning rods on top of buildings copper bus a few feet in diameter?

Dan.


sli...@mailexcite.com

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Apr 9, 1998, 3:00:00 AM4/9/98
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In article <352C766F...@ihug.co.nz>,
no, but they do melt after getting hit.

copper vapour at atmospheric pressure would not be a particularly good
conductor. Incedentally, you'd soon have CuO, not Cu(g).

The ionization of the air, which is what conducts will break down in a matter
of nanoseconds.

-----== Posted via Deja News, The Leader in Internet Discussion ==-----
http://www.dejanews.com/ Now offering spam-free web-based newsreading

dave pierson

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Apr 10, 1998, 3:00:00 AM4/10/98
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In article <352C766F...@ihug.co.nz>, Daniel Wilkes <dwi...@ihug.co.nz>
writes...

>Michael J Edelman wrote:

>> Daniel Wilkes wrote:

>> > Wouldn't you have to use a fairly heavy wire on the rocket or...*poof*
>> > instant copper vapour ?

>> Copper vapor is just as conductive as copper wire! And after the first
>> strike, of course, you have an ionized path that will conduct the following
>> strikes. Only a fine wire is needed to initiate the first strike.

>> If you wanted a wire heavy enough to conduct a strike without melting, you'd
>> have to pull a piece of copper bus a few feet in diameter.

>Are the lightning rods on top of buildings copper bus a few feet in diameter?

About 1 cm, maybe a bit under.
It takes _time_ for melting to occur.
for SHORT (useconds) periods of time, lightning rods & conductors CAN
do it. cf any book by Uman on lightining protection, or any
professional reference on the subject.

thanks
dave pierson |the facts, as accurately as i can manage,
Digital Equipment Corporation |the opinions, my own.
334 South St |
Shrewsbury, Mass USA pie...@gone.enet.dec.com
"He has read everything, and, to his credit, written nothing." A J Raffles
"....the net of a million lies...." Anon

Roger Riordan

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Apr 10, 1998, 3:00:00 AM4/10/98
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sli...@mailexcite.com wrote:

>> > > Wouldn't you have to use a fairly heavy wire on the rocket or...*poof*
>> > > instant copper vapour ?

>> > If you wanted a wire heavy enough to conduct a strike without melting,


>you'd
>> > have to pull a piece of copper bus a few feet in diameter.

>> Are the lightning rods on top of buildings copper bus a few feet in
>diameter?
>>

>no, but they do melt after getting hit.

Lightning conductors, from my observation, are either cables ~ 0.5"
dia, or copper strap maybe 1" * 0.25". If there is a direct hit the
prongs on the top of the conductor might get their ends burnt a bit,
but the cables don't get damaged.

>copper vapour at atmospheric pressure would not be a particularly good
>conductor. Incedentally, you'd soon have CuO, not Cu(g).
>
>The ionization of the air, which is what conducts will break down in a matter
>of nanoseconds.

You can't know much about lightning. The faint leader stroke travels
down from the cloud in a series of steps, at relatively low speed, and
low current. When it reaches ground (or the top of a wire attached to
a rocket) a high power return stroke travels back to the cloud at high
speed along the ionised track left by the leader. I think that the
leader takes a substantial part of a second to reach the ground, so
obviously the ionisation it produces persists for a significant
interval. There are usually several return strokes in quick
succession, again at intervals of a fraction of a second.

The copper wire merely distorts the normal field distribution below
the cloud so that it attracts the leader. Once the return stroke
starts the wire becomes immaterial.


Roger Riordan

Matthew Ornawka

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Apr 11, 1998, 3:00:00 AM4/11/98
to


> You can't know much about lightning. The faint leader stroke travels
> down from the cloud in a series of steps, at relatively low speed, and
> low current. When it reaches ground (or the top of a wire attached to
> a rocket) a high power return stroke travels back to the cloud at high
> speed along the ionised track left by the leader. I think that the
> leader takes a substantial part of a second to reach the ground, so
> obviously the ionisation it produces persists for a significant
> interval. There are usually several return strokes in quick
> succession, again at intervals of a fraction of a second.

Pretty close. While what you say about the leader coming to the ground is true,
you failed to mention the fact that the ground also sends up leaders, several in
fact to meet the leader coming down. The leader coming from the ground is quite
unaware of the ground untill it is a few hundred feet above it and could just
quite easily turn back up to the clouds if it finds a bigger electrical pool to
get drawn toward. As the cloud leader starts its journey down it comes down in
fits and starts, pausing, pooling its charge and taking off in a new direction a
nanosecond later. It does this little jig dozens of times on the way down. When
it gets close enough to the ground, the ground will start to send up little
streamers of its own from a blade of grass, a lightning rod, telephone pole, your
head, anything pointy :-). Only one of the several dozen up-leaders will connect
and when it does, you have the ionized path in which the return stroke hits.
Lightning strobes the way it does because the down-leaders pools of energy are
still up in the cloud and as each pool is tapped you get another strobe... so
lightning will strike more than once in the same spot... it actually hits several
times.

> The copper wire merely distorts the normal field distribution below
> the cloud so that it attracts the leader.

makes it easier to produce an up-leader

> Once the return stroke
> starts the wire becomes immaterial.

yeppers..just me being anal...

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pumpkinboy

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Apr 12, 1998, 3:00:00 AM4/12/98
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Michael J Edelman <m...@mich.com> wrote in article
<352B971B...@mich.com>...
>

>
> If you wanted a wire heavy enough to conduct a strike without melting,
you'd
> have to pull a piece of copper bus a few feet in diameter.
>
>

>And what is more, you would not have lightning, you would have current
flowing through a wire, more useful, less exciting
--
pumpk...@pond.net

-
>
>

Wm James

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Apr 13, 1998, 3:00:00 AM4/13/98
to

)>Are the lightning rods on top of buildings copper bus a few feet in
diameter?
)>
)>Dan.


Actually, lightning rods are not intended to actually attract lightning.

The small point bleeds low voltage off so that the potential for lightning
is reduced.

They do get hit on occasion, and better the rod gets hit than your antenna,
but that's not it's primary function.

William R. James

Bill Nelson

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Apr 13, 1998, 3:00:00 AM4/13/98
to

Wm James (sp...@here.not) wrote:
:
: Actually, lightning rods are not intended to actually attract lightning.

:
: The small point bleeds low voltage off so that the potential for lightning
: is reduced.

I doubt seriously if a rod can bleed of enough power to reduce the earth
potential that develops under a cloud.

From my limited experience, it is nearly always the lightning rod that
is hit.

That would stand to reason. A point makes an good source for generating
an ion stream (can you say "earth based leader"?).

--
Bill Nelson (bi...@peak.org)


Roger Riordan

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Apr 13, 1998, 3:00:00 AM4/13/98
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"pumpkinboy" <pumpk...@pond.net> wrote:

>Michael J Edelman <m...@mich.com> wrote in article
><352B971B...@mich.com>...

>> If you wanted a wire heavy enough to conduct a strike without melting,

>you'd have to pull a piece of copper bus a few feet in diameter.

>>And what is more, you would not have lightning, you would have current
>flowing through a wire, more useful, less exciting

VERY hard to make lightning flowing down a wire useful. Not much
useful you can do with 10-100KA flowing for a few msec. (Unless you
want to go out in a blaze of glory :-)


Roger Riordan

Daniel Wilkes

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Apr 13, 1998, 3:00:00 AM4/13/98
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Roger Riordan wrote:

What about if you paralleled the current into a few (K) Coils, and then bled
the current off slowly?

Dan.


David Keil

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Apr 13, 1998, 3:00:00 AM4/13/98
to

I think using inductors is tough to imposible. However I have heard of
some reasearchers ( fla. I beleve ) using high voltage capacitors to
store some of the energey of a lighting strike.

DNK!

Wm James

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Apr 14, 1998, 3:00:00 AM4/14/98
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On 13 Apr 1998 05:04:31 GMT, bi...@peak.org (Bill Nelson) wrote:

)>Wm James (sp...@here.not) wrote:
)>:
)>: Actually, lightning rods are not intended to actually attract lightning.
)>:
)>: The small point bleeds low voltage off so that the potential for
lightning
)>: is reduced.
)>
)>I doubt seriously if a rod can bleed of enough power to reduce the earth
)>potential that develops under a cloud.
)>
)>From my limited experience, it is nearly always the lightning rod that
)>is hit.
)>
)>That would stand to reason. A point makes an good source for generating
)>an ion stream (can you say "earth based leader"?).


That was the idea behind it.

It works by bleeding it off so that the potiential never gets highenough for
lightning to occur. The idea is sound enough to protect anything under it
at about a 30 degree angle.

You are correct that it also generates the leader, and occasionally attracts
lightning, but it's not what it was designed to do.

William R. James


Bill Nelson

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Apr 15, 1998, 3:00:00 AM4/15/98
to

Wm James (sp...@here.not) wrote:
: )>That would stand to reason. A point makes an good source for generating

: )>an ion stream (can you say "earth based leader"?).
:
: That was the idea behind it.
:
: It works by bleeding it off so that the potiential never gets highenough for
: lightning to occur. The idea is sound enough to protect anything under it
: at about a 30 degree angle.
:
: You are correct that it also generates the leader, and occasionally attracts
: lightning, but it's not what it was designed to do.

The original designers designed the rods to attract lightning, rather than
have it hit some more vulnerable structure. That is exactly what they do.

There is no way that the ion stream could bleed off fast enough. The electrons
just cannot dissipate fast enough to be of any use for reducing the ground
potential significantly.

Read the material on lightning protection that is on the Polyphasor web page
for some enlightening reading.

--
Bill Nelson (bi...@peak.org)


Roger Riordan

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Apr 15, 1998, 3:00:00 AM4/15/98
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Daniel Wilkes <dwi...@ihug.co.nz> wrote:

>Roger Riordan wrote:
..................


>> VERY hard to make lightning flowing down a wire useful. Not much
>> useful you can do with 10-100KA flowing for a few msec. (Unless you
>> want to go out in a blaze of glory :-)

>What about if you paralleled the current into a few (K) Coils, and then bled
>the current off slowly?

Inductors (unless they are superconducting :-) are extremely poor
energy storage devices, and typically can't store energy for more than
a fraction of a second. Capacitors are much better, and in principle
a 10KA current, flowing for 10msec (which I think would be a rather
anaemic stroke) would charge an 0.1F capacitor to 10KV. However such
a capacitor would cost LOTS of money, and the amount of energy stored
is quite small - the equivalent of about 0.2KWh, or roughly what you
can store in a car battery. And its not that easy to do anything
useful with a capacititor charged to 10KV when you've got it.

Also lightning is extremely nasty, with extremely high rate of rise of
voltage, and this can have all sorts of untoward effects. Measured
overvoltages on power lines suffering direct hits range from 2 to
20MV, with a rise time of a few usec, and this would almost certainly
puncture virtually any capacitor if applied directly, even though in
theory you can't change the voltage across a capacitor
instantaneously.

I had a very impressive demonstration of the damaging effects of high
speed transients once, when building a 17KV regulated power supply.
In the regulator I had a resistive voltage divider feeding into an op
amp. To protect the op amp I connected a zener surge suppressor
diode, rated at a maximum of something like 1KA, across the bottom of
the divider, and a series RC filter going to the op amp.

While testing it I used about 10 10Mohm resistors in series, in a
0.25" glass tube, with the lead from the first resistor sticking out
the end, as the high voltage resistor. I connected the divider to a
DVM, and poked it towards the high voltage terminal. A spark jumped
as the wire approached the terminal, but the DVM continued to read
zero. The diode, despite being sold as an ultra high speed surge
suppressor, had shorted. The current flowing through the fraction of
a picofarad capacitance of the probe when the voltage rose to 17KV in
a few nsec, had blown it.

On the other hand did hear of a case once where a drum of high voltage
insulated cable had been left outside during a thunderstorm. After
the storm someone went to move it, but it had been charged by a strike
in the immediate vicinity, and he was either seriously shocked, or
killed, by the residual charge.


Roger Riordan

deKa...@notmail.com

unread,
Apr 15, 1998, 3:00:00 AM4/15/98
to

On Mon, 13 Apr 1998 19:17:49 +1200, Daniel Wilkes <dwi...@ihug.co.nz>
wrote:

>What about if you paralleled the current into a few (K) Coils, and then bled
>the current off slowly?
>

>Dan.


i understand uncle sugar tried to store usable energy from lightning, it
didn't work. built a huge (was it >one farad?) capacitor and waited for the
lightning to strike. it did, and killed about twenty researchers. darwin in
action.

deKaulbe


P.*a.*o.*l.*o.

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Apr 26, 1998, 3:00:00 AM4/26/98
to

On stardate Wed, 15 Apr 1998 09:42:39 GMT , Captain
rio...@werple.net.au (Roger Riordan) wrote:

>Also lightning is extremely nasty, with extremely high rate of rise of
>voltage, and this can have all sorts of untoward effects. Measured

Correct, the voltages can rise (and go down) in microseconds.
Current rise OTOH is nasty. From 0 to a peak of 100,000A in 1us (ok,
it's not an exact value.. it's a guess)

>overvoltages on power lines suffering direct hits range from 2 to
>20MV, with a rise time of a few usec, and this would almost certainly
>puncture virtually any capacitor if applied directly, even though in

Sure. But a lightning can be even 7Km long.
This means voltages varying from 200MV to 7GV (oops, 7 billion V!)
or 1 billion V per Km of length.
Nothing can survive to these monster voltages.
About the enrgy: surprisingly a lightning doesn't carry that much
energy: it's equivalent to (say) 10gallons of gasoline, but imagine
50% of that gasoline burn in 10micro seconds and the rest in a few ms!
This explains the power of a lightning. A local newspaper told about a
house with a 2m^2 hole on the roof and the kitchen cleanly ruptured in
two pieces (yeah!) by the lightning travelling inside the copper
wires.
Btw the copper wires probably detonated, being vapourised to a 30,000
deg plasma in a handfull of microsecons. Try to imagine it.
Usually a lightning transports electric charges coming from a 10Km
radius (and sometimes, *much* more), imagine the cloud acting as a
capacitor and you end up with a giant charge stored in clouds.
An energy of 400million Joules is common.
PS the temperature of a lightning is ranging from 30,000 to 100,000C
depending on the current flowing, and this produces an extremely
bright flash.
The thunder is produced when the dart leader (main discharge) hits the

discharge coming from the earth, at that point the shockwave is
produced (uh, this description is lame, I apologise tothe experts for
this shit). The electric charges are travelling at 150,000Km/s (or
more), when they meet you might expect some sort of boom.
Actually it seems that deviations from a straigth path also produce
shockwaves.

Argh, this piece is awfully written, sorry:(

Well, this is not all,

P*a*o*l*o


ANTISPAM:To Reply remove the garbage chars from my address

"Energy is Ethernal, And Chaos Will Always Win"
-- First and Second Thermodynamics' Principles.
LoN


Tanner Charles

unread,
May 12, 2021, 5:25:57 PMMay 12
to
Anyone still on this thread?

My name is Tanner and I'm doing a research project on rocket triggered lightning. Would love to talk to someone who has done it before!

Thanks in advanced,

Tanner Schaaf
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