RE: Arc length vs pwr

To: "'tesla-at-pupman-dot-com'" <tesla-at-pupman-dot-com>
Subject: RE: Arc length vs pwr
From: Dan Gowin <gowin-at-epic-1.nwscc.sea06.navy.mil>
Date: Thu, 24 Oct 1996 09:33:56 -0000


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From: 	Tesla List[SMTP:tesla-at-poodle.pupman-dot-com]
Sent: 	Tuesday, October 22, 1996 11:25 PM
To: 	Tesla-list-subscribers-at-poodle.pupman-dot-com
Subject: 	Re: Arc length vs pwr

>From cbailey-at-ideanet.doe.state.in.usTue Oct 22 21:43:31 1996
Date: Tue, 22 Oct 1996 16:11:33 -0400 (EST)
From: Christopher Bailey <cbailey-at-ideanet.doe.state.in.us>
To: tesla-at-pupman-dot-com
Subject: Re: Arc length vs pwr

Hi all,  I have been lurking here for some time time now and I have found
the discussion fascinating.  The posts about arc length vs power peaked my
interest, so here's my two cents.

I found (in several volumes) Charles Steinmetz's lectures at the local
used bookstore.  In volume I, he gives the power consumed by an arc as

p = c * l * sqrt(i) 

(c is an empirical constant, l is length, i is current)

The reasoning is that the current is proportional to the cross-section of
the arc, while losses due to convection, radiation, etc. are proportional
to the surface area of the arc.

using the formula 

input power = v^2 * 2 * PI * 60 * c

and some rearranging, the formula is now

l = (a * p^.75) / sqrt(Cs)

p = power, Cs is capacitance (pf)

IF YOU ASSUME CONSTANT CAPACITANCE, the formula matches with an R of
.99980250 with the data posted by Jack Couture

POWER               INCHES                CALC'd
500                 11                    11.55
1000                20                    19.43
2000                32                    32.68
5000                64                    64.97
10000               110                   109.26

using .10926411 for (a/sqrt(Cs))

In light of this I am wondering whether Couture's data was from
a single coil or coils which were run at various power levels -- instead
of many different coils at many different power levels.

Factoring in the capacitance means that coils with small secondary
capacitance would have a somewhat bigger arc length at the same power.

Just my two cents, feel free to disagree, standard disclaimers,

Chris Bailey - cbailey-at-ideanet.doe.state.in.us


Chris,
	I'm new to the coiling community, but, I have to disagree.  Richard
Hull, Richard Quick, and others, including myself. Have come to the conclusion
that, more than just pure input power will dictate arc length. Air pressure, humitity,
and even the Q of your Tesla circuit seam to have a greater effect on arc length.

	I have built two coils to date and both excede your wattage chart by 
20%-40% in arc length. One of the biggest factors I have noticed relates directly
to the amount of ozone in proximity to your coil. If you run a coil in a small garage
for example (Richard Quick) and do it for a while. Generating lots of ozone, you will
get some pretty long arcs. One must remember, ozone conducts very well
(i.e.: the need for vacum spark gaps - quenching). Another example would be,
Bill Wysock trying to fire up his monster Tesla Magnefier in windy conditions. I
won't describe the results, I'll just say the sparks where really short.

	What did I just say. There are more variables in this formula than have been
accounted for. I think more study and research needs to be conducted. 

D. Gowin


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