Long cables to power "ioncraft" to orbit?

[Dirk Bruere at Neopax]

The ioncraft is a method proposed for decades for aircraft and
spacecraft propulsion:

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

The problem with them is their power supplies are much heavy than the
weight they can lift. But why not leave the power supply on the ground
and connect it to the craft by long power cables?

There are carbon fibers that could support their own weight up to
hundreds of kilometer of altitude:

Carbon fiber (Dani Eder)
http://yarchive.net/space/exot­ic/carbon_fiber.html

And power transmission lines carry electrical power up to 250km away
at up to 600 megawatts of power:

Baltic-Cable.
http://www.answers.com/topic/baltic-cable?method=5

This page calculates you can lift 3.91 grams using 7.681 watts of
power or about a ratio of 1 to 2:

Lifter Theory.
http://jnaudin.free.fr/html/lftheory.htm

Then you could lift 1,000,000 kg using 2 gigawatts of power. The space
shuttle main engines produce a maximum of 37 million horsepower, or
27.6 gigawatts of power:

Boeing: Rocketdyne: Space Shuttle Main Engine Amazing Facts.
http://www.boeing.com/defense-space/space/propul/SSMEamaz.html

Then you could leave the large heavy engines and heavy fuel on the
ground and use it just to run electrical generators to drive the
ioncraft.
If the electrical cable was 4 cm wide made of carbon fiber, a 100km
long cable would have volume Pi*.02^2*100000 = 125.7m^3. At a density
of 1800 kg/m^3 for carbon fiber this would be 226,000 kg. Then twice
this number in kilowatts or 452 megawatts would be needed to support
the weight of the wire alone. You could have take this from the 10's of
gigawatts supplied to the ioncraft or have small versions of the lifter
drive all along the length of the power cable itself drawing off some
portion of the power to support each small portion of the cable.
The question: how much power would be lost by sending it along a 100km
long cable?

Use a uwave beam and onboard rectenna

--
Dirk

The Consensus:-
The political party for the new millenium
http://www.theconsensus.org

 

[Keith Williams]

Leaving aside the engineering problems, you have to get to escape
velocity to make orbit and at altitude you run out of air to ionise.

Umm, if you achieve escape velocity you , err, escape (I.e. you've
overachieved)

 

[tadchem]

Charles Jean wrote:

"There are known knowns. These are things that we know we know.
There are known unknowns. That is to say, there are some
things that we know we don't know. But there are also unknown
unknowns. These are things we don't know we don't know."
-Secretary of Defense Donald Rumsfeld

If Rummy really said this, then he is much more widely read than I
would have believed. This is a variation of a quotation from Lady
Burton, attributed as an 'Arabian Proverb':
"Men are four:
He who knows not and knows not he knows not, he is a fool--shun him;
He who knows not and knows he knows not, he is simple--teach him;
He who knows and knows not he knows, he is asleep--wake him;
He who knows and knows he knows, he is wise--follow him!"

Tom Davidson
Richmond, VA

 

[[email protected]]

Charles Jean wrote:



If Rummy really said this,

He did.

then he is much more widely read than I
would have believed. This is a variation of a quotation from Lady
Burton, attributed as an 'Arabian Proverb':
"Men are four:
He who knows not and knows not he knows not, he is a fool--shun him;
He who knows not and knows he knows not, he is simple--teach him;
He who knows and knows not he knows, he is asleep--wake him;
He who knows and knows he knows, he is wise--follow him!"

Yep. Closer to home, note that the first category above is endowed
with what we (meaning sci.physics regulars) refer to as "second order
ignorance", which is the characteristic of many of our cranks.

Anyway, Rummy did say this and many seemingly intelligent people
jumped on this as a "dumb statement", not realizing that it was their
own stupidity they were thus proclaiming.

Mati Meron | "When you argue with a fool,
[email protected] | chances are he is doing just the same"

 

[bz]

If the electrical cable was 4 cm wide made of carbon fiber, a 100km

The working model apparently requires 30 kV to generate the ions.

That implies that you need pretty good insulation on your cables.
You need to take that into account.

Neglecting that weight, (assume we can put a few spacers between the wires
and their weigh will be negligible, for now) the 452 MW will require 15 kA.
15 thousand amps through the 7.5 ohms (that was from 3 cm diameter aluminum
wires, so the weight we need to lift is underestimated by a significant
factor, but it doesn't really matter, as you will see) of the wires will
drop 113 kV.

The power supply will thus need to put out 133 kV.
From this, it should be clear that MOST of the energy will go to heating
the wires. The wire will disipate 1.6 GW and 0.45 GW goes for lifting the
wire itself. The weight of the payload is negligible compared to the wire.

The wires are going to need to be able to dissipate 254 watts for each 3 cm
of length without weakening. I think the 3 cm diameter wire can take it.

Oh, there is one other 'minor' problem.
This craft will only work inside the atmosphere because it uses the motion
of air molecules to do the lifting.

The lift will fall off with altitude.

So, you don't need to worry about lifting 100 km of wire. It can probably
only go to a few hundred thousand feet.

One other minor problem. When it does get up high, it is going to contact
some layers of the atmospher that carry high charges wrt ground.

Of course, you may be able to get back much more energy than the lift took.



--
bz

please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
infinite set.

[email protected] remove ch100-5 to avoid spam trap

 

[CWatters]

It works by ionizing the air by electrical charge thereby
creating an air flow between the electrodes, generating
thrust.

So it won't work in orbit then.

 

[Robert Clark]

So it won't work in orbit then.

The lifter drive is dependent on the density of the air. It gets
weaker at higher altitudes.
You could have the drive propel the craft at a higher acceleration
than normally used with rockets to get to orbital velocity sooner. Or
you could use the lifter drive as a low cost first stage and only carry
fuel for the final stage to orbit. Note this is what was also planned
for hypersonic orbital craft.


Bob Clark

 

[Rich Grise]

Aluminum is almost always used for high voltage power lines. This is
because of its lower weight:

Aluminium's Electrical Uses.
http://www.world-aluminium.org/applications/electrical/

At 2700 kg/m^3, it's weight is only 50% more than carbon fiber. So a 4
cm wide, 100km long aluminum cable would only weigh 340,000 kg. This
compares to 2 million kg for the space shuttle with solid rocket boosters.
While carbon fiber is electrically conductive, you might want to use
aluminum for higher conductivity (lower power loss). Then you would use
carbon fiber to provide strength for the cable.

Or, we could build an 8,000 mile diameter induction coil, or maybe
maglev...

;-)
Rich

 

[Rich Grise]

You are correct.

The discrepancy is in this figure: 2.8*10^(-8) ohm meter Mathcad has 2.655
x 10^-6 ohm cm.

I used 2.655e-6 ohm meters!

I didn't look at the units closely enough.

I should have said 7.512 ohms for two 3 cm wires.

And at 2.7 g/cc, that's lessee...
2.7 * 3.14 * 1.5 * 1.5 * 20000000 = 381,510 kg. Heck, nothing to it! ;-P

Cheers!
Rich

 

[Rich Grise]

On 17 May 2005 12:53:31 -0700, "Robert Clark" <[email protected]>
wrote: [some fantasy]
Leaving aside the engineering problems, you have to get to escape
velocity to make orbit and at altitude you run out of air to ionise.

Umm, if you achieve escape velocity you , err, escape (I.e. you've
overachieved)

Well, a mass driver up the side of Everest would give you sort of
a jump start. ;-)

Cheers!
Rich

 

[Rich Grise]

The wires are going to need to be able to dissipate 254 watts for each 3
cm of length without weakening. I think the 3 cm diameter wire can take
it.

Oh, there is one other 'minor' problem. This craft will only work inside
the atmosphere because it uses the motion of air molecules to do the
lifting.

The lift will fall off with altitude.

So, you don't need to worry about lifting 100 km of wire. It can probably
only go to a few hundred thousand feet.

Heck, with that much aluminum you might as well just build a tower. ;-)

Cheers!
Rich

 

[bz]

Well, a mass driver up the side of Everest would give you sort of
a jump start. ;-)

You would certainly have one heck of a pair of jumper cables.




--
bz

please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
infinite set.

[email protected] remove ch100-5 to avoid spam trap

 

[Eric Chomko]

tadchem ([email protected]) wrote:

: Charles Jean wrote:

: <snip>

: > "There are known knowns. These are things that we know we know.
: > There are known unknowns. That is to say, there are some
: > things that we know we don't know. But there are also unknown
: > unknowns. These are things we don't know we don't know."
: > -Secretary of Defense Donald Rumsfeld

: If Rummy really said this, then he is much more widely read than I
: would have believed. This is a variation of a quotation from Lady
: Burton, attributed as an 'Arabian Proverb':
: "Men are four:
: He who knows not and knows not he knows not, he is a fool--shun him;
: He who knows not and knows he knows not, he is simple--teach him;
: He who knows and knows not he knows, he is asleep--wake him;
: He who knows and knows he knows, he is wise--follow him!"

The question is, which one is Rumsfeld?

: Tom Davidson
: Richmond, VA

 

[Bob Monsen]

Heck, with that much aluminum you might as well just build a tower. ;-)

How about a 'beanstalk'? Arthur C Clark talked about a structure which
is, effectively, a tower which is long enough so that the centrifugal
force counterbalances the gravitational attraction. Various SciFi
writers have described them. One of the {Red|Green|Blue} Mars series by
Kim Stanley Robinson, has a wonderful description of a tether being
attacked by terrorists, having it's attach point blown up, and wrapping
around the planet at near orbital velocity, destroying everything near
the equator.

 

[Rich Grise]

How about a 'beanstalk'? Arthur C Clark talked about a structure which
is, effectively, a tower which is long enough so that the centrifugal
force counterbalances the gravitational attraction. Various SciFi
writers have described them. One of the {Red|Green|Blue} Mars series by
Kim Stanley Robinson, has a wonderful description of a tether being
attacked by terrorists, having it's attach point blown up, and wrapping
around the planet at near orbital velocity, destroying everything near
the equator.

That's a little silly. If it was tethered, and it was the centrifugal
force keeping it up there, wouldn't it have just flown off into space,
like a slingshot?

Also, for it to be held up by centrifugal force, wouldn't it have
to be higher than a Clarke orbit? I.e., 22,500 miles or so?

Thanks,
Rich

 

[Bob Monsen]

That's a little silly. If it was tethered, and it was the centrifugal
force keeping it up there, wouldn't it have just flown off into space,
like a slingshot?

Also, for it to be held up by centrifugal force, wouldn't it have
to be higher than a Clarke orbit? I.e., 22,500 miles or so?

It's not actually scifi. There are lots of advocates of orbital tethers.
The one in Red Mars was constructed out of one of the moons, by
'growing' the tether in both directions. I guess they had to shift the
orbit of the moon first, so it was geostationary, but hey, it was scifi.

Also, that means my 'centrifugal force' explanation was bogus. It would
be, effectively, orbiting with the planet, with the center of mass in a
geostationary orbit.

In the story, when the tether was cut, something caused it to contact
the ground, which created friction, effectively bringing the entire mass
down over a period of a few hours or days. I can't remember many of the
details, and somebody seems to have 'borrowed' my copy of the book.

 

[Ken Taylor]

It's not actually scifi. There are lots of advocates of orbital tethers.
The one in Red Mars was constructed out of one of the moons, by 'growing'
the tether in both directions. I guess they had to shift the orbit of the
moon first, so it was geostationary, but hey, it was scifi.

Also, that means my 'centrifugal force' explanation was bogus. It would
be, effectively, orbiting with the planet, with the center of mass in a
geostationary orbit.

In the story, when the tether was cut, something caused it to contact the
ground, which created friction, effectively bringing the entire mass down
over a period of a few hours or days. I can't remember many of the
details, and somebody seems to have 'borrowed' my copy of the book.

I don't recall a detailed explanation being in the book, but friction due to
atmospheric drag would slow the bottom of the tether pretty quickly so as to
cause problems, then once it's unstable it's manure and impellor time.

Ken

 

[[email protected]]

The working model apparently requires 30 kV to generate the ions.

That implies that you need pretty good insulation on your cables.
You need to take that into account.

Neglecting that weight, (assume we can put a few spacers between the wires
and their weigh will be negligible, for now) the 452 MW will require 15 kA.
15 thousand amps through the 7.5 ohms (that was from 3 cm diameter aluminum
wires, so the weight we need to lift is underestimated by a significant
factor, but it doesn't really matter, as you will see) of the wires will
drop 113 kV.

The power supply will thus need to put out 133 kV.
From this, it should be clear that MOST of the energy will go to heating
the wires. The wire will disipate 1.6 GW and 0.45 GW goes for lifting the
wire itself. The weight of the payload is negligible compared to the wire.

The wires are going to need to be able to dissipate 254 watts for each 3 cm
of length without weakening. I think the 3 cm diameter wire can take it.

Oh, there is one other 'minor' problem.
This craft will only work inside the atmosphere because it uses the motion
of air molecules to do the lifting.

The lift will fall off with altitude.

So, you don't need to worry about lifting 100 km of wire. It can probably
only go to a few hundred thousand feet.

One other minor problem. When it does get up high, it is going to contact
some layers of the atmospher that carry high charges wrt ground.

Of course, you may be able to get back much more energy than the lift took.

Just as with electrical power transmission over long distances, you
will use very high voltage, probably in the megavolt range, that is, if
you want to lift megakilos.
In the demonstrations for small lifters, kilovolts were used to lift
only a few grams a few feet.
Since the lifter uses air for its reaction mass, you could use a
higher acceleration than that normally used for rockets to reach
orbital velocity at a lower altitude so the air is at sufficient
density. But this would reduce the lift capacity. That is, if you
accelerated at 3.6 g's, you could lift one third the mass than at 1.2
g's.
Or you could use a shallower trajectory than that used by rockets so
that most of the acceleration phase stays in the lower atmosphere. But
this would necessitate a longer and heavier cable.
Probably a combination of these would be optimal.


Bob Clark

 

[Oren Tirosh]

The ioncraft is a method proposed for decades for aircraft and
spacecraft propulsion:

Lifters have only been proposed for spacecraft propulsion by the
"asymmetric capacitor" nuts who claim they work in vacuum with no
reaction mass. It may be useful for high altitude launch, though.
Lifters should be able to hover in the no-man's land above aircraft and
balloons and below stable orbit altitude where only rockets make brief
visits. A gentle ride through the thick atmosphere and separation in
near vacuum should make it much easier for the upper stage.

The wispy wire mesh structure of an ion lifter should make a good
recantenna for transmitting power by microwave without a big increase
in total weight. Transmission efficiencies in the two-digit percentage
range have been demonstrated over long distances. I believe this should
be much more practical than cables - assuming the lifter itself is up
to the task.

Lifter efficiency should probably need to be improved by almost an
order of magnitude. Evgenij Barsoukov (original source of the lifter
theory page you refer to) has some promising ideas for improving
efficiency. He has derived equasions that accurately predict ion lifter
performance and seems to be one of the few people in the lifter scene
who really know what they are talking about.

Oren

 

[[email protected]]

Use a uwave beam and onboard rectenna

Such experiments are being conducted:

6-GHz Microwave Power-Beaming Demonstration with 6-kV Rectenna and
Ion-Breeze Thruster.
T. Cummings,* J. Janssen,* J. Karnesky,* D. Laks,* M. Santillo,* B.
Strause,* L. N. Myrabo,* A. Alden,¶ P. Bouliane,¶ and M. Zhang¶
*Department of Mechanical, Aerospace and Nuclear Engineering,
RensselaerPolytechnic Institute, Troy, New York 12180
¶Communications Research Centre, Ottawa, Ontario, Canada
"On 14 April 2003 at the Communications Research Center (CRC) in
Ottawa, Ontario, a 5.85-GHz transmitter beamed 3-kW of microwave power
to a remote rectifying antenna (i.e., rectenna) that delivered 6-kV to
a special `Ion-Breeze' Engine (IBE). Three of CRC's 26.5-cm by 31-cm
rectennas were connected in series to provide the ~6-kV output. RPI's
low-voltage IBE thrusters performed well in a "world's first"
power-beaming demonstration with rectennas and endoatmospheric
ion-propulsion engines. The successful tests were a low-tech,
proof-of-concept demonstration for the future full-sized MicroWave
Lightcraft (MWLC) and its air breathing `loiter' propulsion mode.
Additional IBE experiments investigated the feasibility of producing
flight control forces on the MWLC. The objective was to torque the
charged hull for `pitch' or `roll' maneuvers. The torquing
demonstration was entirely successful."
http://proceedings.aip.org/getabs/s...prog=normal&id=APCPCS000702000001000430000001

This is from the 2nd Beamed Energy Symposium:

BEAMED ENERGY PROPULSION: Second International Symposium on Beamed
Energy Propulsion.
http://proceedings.aip.org/dbt/dbt.jsp?KEY=APCPCS&Volume=702&Issue=1

A possible problem here is the power drop off with long distances, say
at the several kilometer range. You might need an exorbitant amount of
energy to be beamed in order to receive megawatts to gigawatts at the
vehicle. With the cable, a simple estimation shows you would only lose
a few percent from gigawatts of power over a hundred kilometers if the
voltage was kept in the megavolts range and you used highly conductive
aluminum.
Beamed energy is being investigated by Leik Myrabo for his
"Lightcraft." Admittedly this is using a different propulsion method
but it may be indicative of the energy requirements for beamed
propulsion:

Highways of Light,
Scientific American, February 1999,
http://www.sciam.com/article.cfm?colID=1&articleID=00058731-ED4B-1CB8-B4A8809EC588EEDF

The Myrabo laser system uses a 10 kilowatt laser to lift a 50 gram
Lightcraft about 100 ft. in the air. This is a 200 to 1 ratio of power
in watts used to the weight lifted in grams. Their goal is to lift a 1
kilo craft to orbit using a 1 megawatt laser. This is a 1000 to 1 ratio
of power used to weight lifted.
Myrabo et.al. are also investigating a microwave version of the
Lightcraft:

2. MICROWAVE LIGHTCRAFT.
http://www.geocities.com/tonylance/liteship.html#bertha

Here, 30 megawatts would be used to launch a 30 kilogram craft. This
is a 1000 to 1 ratio of power in watts used to the weight lifted in
grams. In the cable-powered lifter scenario it's about 2 to 1.
In any case we don't have laser beams or microwave tranmitters that
can put out gigawatts of power. I'm suggesting we have generators that
can put out this much power. We could begin start the process to start
lifting megakilo payloads *tomorrow*.


Bob Clark