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Towards the autonomous lifter - electrostatic voltage generators.



Original poster: Robert Clark <bobbygc2001@xxxxxxxxx>

Key for a "lifter" drive becoming a generally useful
propulsion method is an electrical power source
lightweight enough to be lifted by the lifter drive:

Ioncraft.
http://www.markwilson.com/ionc­raft/ioncraft.html

It works by ionizing the air by electrical charge
thereby creating
an air flow between the electrodes, generating thrust.
There are
several examples of these, called "lifters", made by
amateurs:

The Lifters Experiments home page by Jean-Louis
Naudin.
http://jnaudin.free.fr/lifters­/main.htm

Electrostatic high voltage generators may prove to an
answer for
such a power source.
Electrostatic high voltage generators have existed
since the 18th
century. They were earlier called electrostatic
influence machines.
This page of Antonio Carlos M. de Queiroz calcutes the
current that
can be generated by an electrostatic influence
machine:

Maximum electric field.
http://www.coe.ufrj.br/~acmq/e­field.html

(For anyone who had the same problem as I did opening
this site, you
can get the Google cached version here:

Maximum electric field.
http://64.233.161.104/search?
q=cache:Su6AOXBIC9EJ:www.coe.ufrj.br/~acmq/efield.html
)

Note that it is dependent on the product of the
dielectric constant
of air and the breakdown voltage of air.
Then since the dielectric constant of the air and
vacuum are about
the same but the breakdown voltage of the vacuum is
immeasurably
high, you can achieve much higher currents enclosing
the device in a
vacuum.
Various types of electrostatic generators are
described on this
page of de Queiroz:


Electrostatic Machines. http://www.coe.ufrj.br/~acmq/e­lectrostatic.html

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 for
our
application than a Van de Graaff generator.
Another interesting possibility might be the voltage
doubler. As
the name implies it doubles the applied voltage with
each cyclic
turn of the rotors:

The Bohnenberger machine.
http://www.coe.ufrj.br/~acmq/b­ohnenberger.html

Take a look at the graph on this page to see how the
voltage is
doubled at each cycle. The doublers are limited in
voltage in air by
the sparking that is produced. The voltage possible in
vacuum should
be markedly higher.
Another possibility might be the generators that use a
vertical
cylinder as a rotor. From de Queiroz "Maximum electric
field" page
you see the current produced is proportional to the
surface area of
the rotor and the speed of rotation. But there are
limits to the
rotational speed for real materials since they would
fall apart from
the internal stresses.
Keeping the speed low but increasing the radius of a
flat disc
raises the same problem because the speed on the edge
of the disk
will be higher. However, a vertical cylinder solves
this since you
get increased surface area by making the cylinder long
while the
internal stresses from the rotation are only operating
radially.
The key factor in using an electrostatic generator for
the power
supply is that they can serve as both the source of
the electrical
power and the source of the high voltage generation -
you don't need
separate power supply and transformer.
That they act as source for high voltage is known, but
the reason
they can act as the power source for our application
is they are in
effect flywheel batteries. Then at launch you induce
the rotors to
spin at high speed by either mechanical or electrical
means and as
with any flywheel they would act as a means of power
storage. Note
that with the most advanced flywheel batteries you
enclose the
flywheel in vacuum to keep the time the flywheel spins
to a longer
period by reducing air friction, and they also use
magnetic bearings
to reduce the friction from the support of the rotor.
Then this
dovetails nicely with the requirement to have them in
vacuum to
increase voltage attained.
A file in the Yahoo Lifters group calculates
remarkable power
generation for a moderately sized vacuum electrostatic
generator:

Lifters.
http://groups.yahoo.com/group/­Lifters/

The file named "Electrostatic HV Supply.PDF" appears
in the Files
section in that group. It was copied from a book on
high voltage
generation and claims for a generator operating in
high vacuum with
50 rotors, 4 feet in diameter rotating at 4,000 RPM
could generate 1
MV and 7 megawatts of power. Note that key in its
being able to
deliver this power is the rotors operating in vacuum
where much
higher voltage gradients are possible, 1 MV/cm or 100
MV/m in this
case. In air you might be able to get only 3 MV/m.
Then assuming
approx. a 1 to 1 thrust(in grams) to power(in watts)
ratio, this
could lift 7,000 kg.
Key would be making the rotors light weight. Then work
on advanced
flywheel batteries that use carbon composites for the
flywheel would
be helpful here:

Composite Rotor Lifetime Testing.
http://www.utexas.edu/research­/cem/composite%2
0rotor%20testi­ng.html

Flywheel Energy Storage.
http://www.upei.ca/~physics/p2­61/projects/flyw
heel1/flywheel­1.htm

Flywheel Basics Tutorial.
http://rpm2.8k.com/basics.htm


Bob Clark