# RE: Rotary gap safety - RE: spark gap muffler?

```Original poster: "Loudner, Godfrey by way of Terry Fritz <twftesla-at-qwest-dot-net>" <gloudner-at-SINTE.EDU>

Hi All

With the following formula, you can reproduce the table below.

v = (Pi)wd/1056 where v = tangential velocity, w = RPM, d = diameter of
disc, and Pi = 3.14159.

Godfrey Loudner

> -----Original Message-----
> From:	Tesla list [SMTP:tesla-at-pupman-dot-com]
> Sent:	Tuesday, May 29, 2001 1:14 PM
> To:	tesla-at-pupman-dot-com
> Subject:	Re: Rotary gap safety - RE: spark gap muffler?
>
> Original poster: "Christopher Boden by way of Terry Fritz
> <twftesla-at-qwest-dot-net>" <chrisboden-at-hotmail-dot-com>
>
> > > >Hi Terry, Chris, et al!
> > > >
> > > >Here is a quick table of how fast things are thrown from the edge of
> a
> >disk
> > > >running at 3600 RPM. As you can see, things get real nasty, real
> quick.
> > > >Diam    Tangential
> > > >(in.)        velocity (mph)
> > > >4.00 42.8
> > > >5.00 53.5
> > > >6.00 64.3
> > > >7.00 75.0
> > > >8.00 85.7
> > > >9.00 96.4
> > > >10.00 107.1
> > > >11.00 117.8
> > > >12.00 128.5
> > > >
> > > >Matt D.
> > >
> > > Great chart Matt, but if we evaluate 128 mph, it is only about 1/7
> > > the speed of a normal bullet, and my 30-30 lead bullet weighs close
> > > to what a 3/8" X 1" tungsten electrode would. :)
> > > Steel plate isn't out of the question though, very compact, just
> > > expensive, I'd probably use wood if I had a need to armor.
> > > I agree that steel is a good idea for a publicly exposed unit!
> >
> >
> >
> >I agree! When dealing with the public, it only takes one "Oh S _ _ _ !"
> to
> >wipe out a lot of accumulated "Bravos!"
>
> Fortunately, with our demonstartions, any mistakes (frying a piece of
> gear,
> etc) usually look like part of the demo. By the time a given piece of gear
>
> makes it to the demo it has been tested a couple hundred times in the
> shop.
> We try to push it as much as we dare in the lab, but only 80% of capacity
> in
> a demo, that way we're less likely to smoke something in public.
>
> It took us about a year to learn how to do decent demos though. Our early
> Tesla Coil demos were of varyable length and always ended when something
> failed. We literally would hope to make it at least about 10 minutes of
> total run time and the demo went until the gap melted, or the caps
> punctured, etc...
>
> It's so nice to be ahead of the curve now, lol
>
>
>
> True, the velocity is much less than
> >a 30-30 bullet,
>
> ahhh but the mass is far more :) Our rotor is spinning at 1800, with 12
> electrodes made from a 1.5" long .5" brass bolt. These things are very
> heavy. They're drilled out for 3/32" tungsten electrodes.
>
>
> but as mothers all over the world have said about BB guns,
> >"You'll put your eye out with that"
> >
> >Matt D.
> >Q. Do parachutes fail to open very often?
> >A No, just once.
>
> duck
>

```