Re: [TCML] Brent Turner Playing "Thor" on History Channel THE REAL STORY

[bturner@xxxxxxxx]

THE actual Brent Turner here. It's been a awhile.

I keep noticing from time to time when either myself or Danielle make a
'media appearance', there is a flurry of posts, usually revolving around
the following topics;

1) How do we do it. (What is the 'trick')
2) Why is it done in some place out in nowhere.
3) References to Danielle really not 'knowing' what she is doing.
4) Ground-stroke 'power arcs'

I'm making this post in order to help set the record straight, and also to
hopefully address the technical side just a bit to show that yes, there
really IS the element of physical injury. That's why it's called a STUNT.

The bottom line here is that we do this as a PERFORMANCE AND STUNT.
Meaning, media concerns hire us. They (usually) aren't interested in
technical details nor prowess. They want the glitz and the sparks. Period
end of statement.

Jeff (of kVA Effects) is correct, insurance issues unfortunately do limit
us, HOWEVER, the most recent presentation ("Superhuman") on History
Channel was shot out at Vasquez Rocks because the producer was a Star Trek
fan, and that's were many original TV episodes were filmed. (It's actually
a very common shooting location.) We have, and continue to, setup and film
within conventional studios as well. The Ripley's filming was problematic
from the beginning - the very long distance was for crowd control NOT
spark control. There simply was NO WAY to 100% prevent someone in the
crowd from running up close and possibly getting nailed with a
ground-stroke discharge. And constructing a Faraday fence was impractical
and visually disrupting. With the longer distance, it gave us additional
reaction time. That's all. In closed-set conditions, I will say that the
cameras and such are definately closer.

Danielle is a performer, her specialty is really NOT Tesla coils, as I am
sure most people here have determined. Danielle HAS, however, worked with
my system for many, many years, and though she did join the 'million volt
head spark' club, the set layout and my safety specs prevented that from
becoming a full ground-stroke discharge - it was a high impedance
discharge path into the surrounding air. It stung briefly of course. (And
it's happened to me too.) We rehearse and review at EVERY performance,
coordinate with the producer, etc.


*** GROUND STROKE ARCS ***


Yes, these are DANGEROUS. PERIOD. Even with the coil producing HF, what
many people (except those who study or understand the complex waveform
structures) do NOT realize is that it's not JUST the HF. That hot power
arc has a LOT more things going on - sure, it's 'a shorting' across the
secondary, however, since the coil itself is air core and loosely coupled,
not a lot of that 60Hz really gets coupled across the system. That's not
where the danger lies.

And no, I am not going to 'give away' the secret (as there really isn't one.)

The Tesla coil charges it's topload (torroid, globe, Danielle on the
table, etc) quite rapidly during 'ring-up', a ground-stroke allows that
topload to rapidly discharge as a current pulse rather than a progressive
stepped-leader discharge into the air.

We have approximately 90pf or so of topload with Danielle on the table.
Taking a conservative estimate of 650-700Kv for the PEAK secondary impulse
voltage rise, with the conventional e=1/2CV2, this works out to 18-20
JOULES of energy discharging in a matter of microseconds. A medium-sized
camera flash unit with 450uF cap charged to 400 volts works out to about
35 joules.

In ADDITION, in the case of my Tesla coil, the primary tank circuit fires
at 600pps - that's 600 pulses PER SECOND. Now conventional wall current
alternates at 60HZ (in reality, the Vpeaks occur at 60pps). If 60Hz wall
current causes muscle contraction and defibrillation of the heart, 18
joule impulse discharges at 600pps are going to be even nastier. On the
plus side though, the current duration is extremely short, far shorter
than with 60Hz wall current. It's more like an EXTREMELY high-powered
'stun gun'.

In a nutshell, the 'power arc' represents 18 joule pulses hammering
anything in it's conductive path at 600 pulses per second. "Electric
Fences" send out far less pulse energy and at a much lower rate. And those
are no fun to hold onto, are they? Most heart defib units deliver 50-200
watt-seconds (joules). At the very least, a 20-joule, high repetition rate
current path can wreck havoc with the cardiac sinus rhythm as well as
blockading neuromuscular signals.

Now, as a final note to all of this, I myself will no longer be able to
perform on top of the lightning table. Due to a most unfortunate onset of
sudden hearing loss, I now have a Cochlear Implant device to allow me some
semblance of hearing. I now have a complex computer chip inside my head,
and thin wires running into the nerve endings in the cochlea. ***ANY***
unintended current paths in the surrounding tissue area can destroy that
chip, as well as possibly cause permanent and irrevocable auditory nerve
damage.

YES PEOPLE, THE DANGER IS REAL.



- Brent Turner


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