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Pig Bladder
Dear Robert Clark:
Corona inception in a vacuum is around 270 volts. What do you mean by
"immeasurably high"?
David A. Smith
I think this horse is long dead.
Dear Robert Clark:
Corona inception in a vacuum is around 270 volts. What do you mean by
"immeasurably high"?
David A. Smith
Robert said:Key for lifter drive becoming a generally useful propulsion method is
an electrical power source lightweight enough to be lifted by the
lifter dirve. Electrostatic high voltage generators may prove to an
answer for such a power source.
Robert said:Key for lifter drive becoming a generally useful propulsion method is
an electrical power source lightweight enough to be lifted by the
lifter dirve. 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 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 rotor testing.html
Flywheel Energy Storage.
http://www.upei.ca/~physics/p261/projects/flywheel1/flywheel1.htm
Flywheel Basics Tutorial.
http://rpm2.8k.com/basics.htm
Bob Clark