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Re: Towards the autonomous lifter - electrostatic voltage generators.
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- Subject: Re: Towards the autonomous lifter - electrostatic voltage generators.
- From: "Tesla list" <tesla@xxxxxxxxxx>
- Date: Thu, 09 Jun 2005 22:13:08 -0600
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Original poster: Robert Clark <bobbygc2001@xxxxxxxxx>
--- Tesla list <tesla@xxxxxxxxxx> wrote:
> Original poster: "Antonio Carlos M. de Queiroz"
> Tesla list wrote:
> >Original poster: Ed Phillips <evp@xxxxxxxxxxx>
> >"Especially useful for our methods might be the
> >Wimhurst, Wehrsen,
> >Holtz, or Bonetti machines. I believe these devices
> >would be able to
> >deliver more current and therefore greater wattage
> >application than a Van de Graaff generator."
> > Not sure about it, but I think that ES motors
> have a very poor
> >power/weight ratio, and are probably quite
> inefficient. Antonio would
> >know about that. Has anyone calculated the power
> required to operate a
> >lifter of useful size?
> Apparently, the required voltage is not so high,
> maybe less than 20 kV,
> but the current is high, more than 1 mA for a small
> It's not simple to build an electrostatic generator
> that can produce
> 1 mA, operating in normal air. My most powerful
> machines produce
> just 100 uA, and I can't power a lifter with just
> this. I tried,
> a significant "wind" is produced, but not enough to
> lift the device.
> Maybe if I manage to build a very light one. An
> electronic power
> supply, maybe using a Tesla-coil transformer (air
> core) and a suitable
> rectifier may be more practical than an
> electrostatic generator,
> when weight is the critical factor. A 1 mA
> electrostatic machine
> would weight many kilograms, not counting the motor
> to power it.
> Antonio Carlos M. de Queiroz
Thanks for the responses. There have been lifters
made that have a thrust to power ratio of about 1 to 1
measured in grams lifted, to power required in watts.
In particular a lifter created by Blaze Labs produced
a lifter weighing about 200 grams powered by a 200
watt power supply.
Antonio, it looks like the thickness of the rotor
should have no effect on the production of the charge,
what's important is the surface area and the speed of
rotation. So instead of being millimeters thick, you
could make it microns thick. In fact you might be able
to make the rotor 1/100th as thick so 1/100th as
heavy. Since the rotor would be 1/100th as heavy the
support structure would probably also have to be only
1/100th as heavy.
But the rotor has to rotate at high speed to generate
sufficient current; so this very thin rotor has to be
very stiff. One way would to have strong stiff rods
inserted radially into the rotor material to maintain
its stiffness. You probably wouldn't need many of
these to keep it stiff so the weight would stay low.
Also, on your page you mentioned a rotation speed of
about only 40 rotations per sec. I want to use at
least 10 times that high. You might want to use an
electrical motor to get it up to this speed, for
example a vacuum machine motor.
Speaking of vacuum, electrical breakdown requires the
medium to become a conductor, like a metal. Since
there is no "medium" in a vacuum I was assuming this
would require some immensely high voltage to where
bizarre quantum mechanical effects come into play like
However, I am informed that in practice what happens
is that at moderately high voltages emitted electrons
from the electrodes and even trapped gases in the
electrodes can cause currents to flow across the
This voltage depends on alot of factors with the
electrodes: smoothness, trapped gas content,
cleanliness, etc. Some high voltages I've seen for
this were in the range of 150 MV/m, which explains why
in the example the voltage given was 100 MV/m and not
some immeasurably high voltage.
Since the breakdown in air is only at about 3 MV/m,
in a vacuum you could go 30 to 50 times higher thereby
generating that much more power.
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