Long cables to power "ioncraft" to orbit?

Tue May 17, 2005 7:53 pm   

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?


Bob Clark

Wed May 18, 2005 5:20 am   

Rich Grise wrote:

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.


Bob Clark

Wed May 18, 2005 1:18 pm   

bz wrote:

This page gives the resistance over 200 km for a 3 cm diameter cable
as only 7.9 ohms:

Electric Current.
"A high voltage transmission line has an aluminum cable of diameter
3.0cm, 200km long. What is the resistance of this cable? Solution:
The resistivity of aluminum is 2.8*10^(-8)ohm-m. the length of the
cable is 2*10^5m. The diameter of the cable is 3cm and its
cross-sectional area is equal to Pi*(d/2)^2 or 7.1*10^(-4) m^2.
Substituting these values into R = rL/A the resistance of the cable can
be determined.
R = (2.8*10^(-*2*10^5)/( 7.1*10^(-4)) = 7.9 ohms".
http://electron9.phys.utk.edu/phys136d/modules/m6/current.htm

For a wider cable the resistance will be less in proportion to the
cross-sectional area.


Bob Clark

Wed May 18, 2005 3:13 pm   

Rich Grise wrote:

Not to mention all of the untangling that would be
required after each launch.

- Ed Kyle

Wed May 18, 2005 8:01 pm   

Charles Jean wrote:

<snip>


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

Thu May 19, 2005 11:45 am   

CWatters wrote:

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

Fri May 20, 2005 6:39 am   

bz wrote:

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

Fri May 20, 2005 7:48 am   

Robert Clark wrote:

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

Fri May 20, 2005 8:04 am   

Dirk Bruere at Neopax wrote:

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/servlet/GetabsServlet?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

Fri May 20, 2005 5:04 pm   

bz wrote:

You would locate the launcher at the gigawatt scale at very dry areas.
While transmission lines typically carry hundreds of kilovolts some do
go up to a million volts.
Using voltages in the hundreds of kilovolt range, power stations
already exist that transmit gigawatts of power over hundreds of
kilometers:

Quebec - New England Transmission.
http://www.answers.com/main/ntquery?method=4&dsid=2222&dekey=Quebec+-+New+England+Transmission&gwp=8&curtab=2222_1


Bob Clark

Fri May 20, 2005 5:12 pm   

rgregoryclark_at_yahoo.com wrote:

As Al says, getting to 100km is a no-brainer. You can use lots of
fairly simply methods to get that high. IIRC, it's not *that* much
higher than balloon records.

But the shuttle, which you want to compare to, thrusts for something
like 5 or 6 minutes to reach orbit. It goes *MUCH* farther than 100km
while still under thrust. You should be thinking more like 3000km
than 100km. IIRC, engine shutoff is someplace over Europe or so.
Multiply that 3.4E5 kg by 30 and it don't look so good any more.

In addition, the strongest cable yet manufactured is not going to
hold its own weight at 100km. (It's probably not going to do it at
10km, though I won't take any bets on that.) Do you feature a 4cm
cable holding 340,000 kg? Never mind doing it while this vehicle
is blasting away at many g's through the air.

Can you say "twang?" Knew you could. Cables have some stretch,
and then they snap. That would be pretty impressive for all
concerned. This many km long cable snaps someplace in the
middle, and both ends coil back to their connections. The
ground end snaps back pulverizing anybody silly enough to
be watching from the launch site. The sky end smacks into
the vehicle, at a relative velocity of "too many I'm sure,"
slicing it neatly into dozens of chunks. This shrapnel then
finishes up falling onto whoever happens to be downrange,
all at a velocity of several km/s. In 100 tonne amounts.

This could cause the neighbours to complain.

And even if the damn thing could work, you'd wind up with
this string of wire hanging in mid air, then falling back
with a certain amount of dispatch. The neighbours might be
more seriously pissed the higher the fool thing got. What
would, say, Span have to say if a multi-thousand-km cable
were to be dropped on them at orbital speeds? I doubt it
would resemble "Ole!"
Socks

Sun May 22, 2005 9:26 am   

Puppet_Sock wrote:

There are a couple of ways of dealing with the horizontal distance
component of the trip. Let's say the lifter craft is moving in a
straight-line, not straight-up but at some inclination, at a constant
velocity a along this straight-line. Then the speed along this
straight-line will be v=a*t and the distance along this straight-line
will be s=(1/2)*a*t^2.
Eliminate t from these two equations to get 2*a*s=v^2. If you want v to
equal orbital velocity, about 8000m/s, then a*s = 32*10^6. If you want
s , which will be the length of the cable, to be 100,000m, then a = 320
m/s^2, about 32 g's (using g as approx. 10 m/s^2). For this
acceleration you would want the payload just to be cargo. The purpose
of this is to make launches of megakilo payloads possible at low cost
remember. Electronics can easily be hardened to withstand this
acceleration. Note also the time would only be t = v/a = 8000/320 = 25
seconds.
Or you could make the distance be 5 times longer, making the cable 5
times heavier, and the acceleration would be 6.4 g's. This is probably
within the range humans can take for a few minutes:

QUESTION:
How much speed can a body's organs take in space?
"In the case of the Space Shuttle, this acceleration is around 3 times
the force of gravity - 3g - making the crew feel three times their
normal weight, but in the early days of manned space flight, the
astronauts had a rougher ride. The Mercury capsules launched by the
Atlas booster reached a peak acceleration of 8g during ascent to orbit,
then decelerated during re-entry at loads as high as 7.8g. The Titan
rockets launched the Geminis at 7.25g, and the Saturn 5 peaked at 4g.
However, the Apollo capsules returning from the Moon re-entered the
atmosphere at over 6g."
http://quest.arc.nasa.gov/saturn/qa/new/Effects_of_speed_and_acceleration_on_the_body.txt

Astronauts probably could take 15 g's acceleration for short periods:

Armstrong.
"18 June 1959 - Centrifuge program to investigate the role of a pilot
in the launch of a multi-stage vehicle.
A centrifuge program was conducted at Johnsville, Pennsylvania, to
investigate the role of a pilot in the launch of a multi-stage vehicle.
Test subjects were required to perform boost-control tasks, while being
subjected to the proper boost-control accelerations. The highest
g-force experienced was 15, and none of the test subjects felt they
reached the limit of their control capability. As a note of interest,
one of the test subjects, Neil Armstrong, was later selected for the
Gemini program in September 1962."
http://www.astronautix.com/astros/armtrong.htm

The time at this acceleration would be 8000/150 = 53.3 seconds.
The disadvantage of using such high accelerations even for cargo is
that you could lift proportionally smaller weight. That is,
accelerating at 32 g's you could lift only 1/10th the cargo as at 3.2
g's.

So another possible solution would be to allow the total cable length
to be longer but having only a smaller portion say 100 km to be in the
air, the rest lying on the ground. You could for example have a 500km
cable length laid out beforehand on the ground. The lifter would launch
with the bottom end of its tethered cable running along the portion of
the cable on the ground. Then you could have a gentler acceleration,
about the same as for a 500km long powered flight, 6.4 g's, but the
weight of the cable that had to be supported in the air would stay at
the weight of 100km of cable.
Note that during the flight and after disconnect you probably want the
cable to be supported by smaller lifter devices along its length. This
would allow it to be returned to the launch site for reuse.
Carbon fiber can support its weight up to 300 km in height. But even
if you used aluminum the weight of the cable probably would be
supported over its length by small lifter devices anyway.
Just as with shuttle launches the lifter craft launches would be
directed to not be over populated areas during the period of powered
flight.
For the power drain, a cable 600 km long would take up to 6 times as
much power. So if the drain was 5% at 100 km, it would be 30%. You
would increase the power generated to make up for this loss.


Bob Clark


Bob Clark

Sun May 22, 2005 4:42 pm   

George Dishman wrote:


????

The point of this thread is the savings in power you would get by
using a lifter thruster method.
Look at the table near the bottom on this page:

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

The last line in this table labled Thrust(g)/Power(W) ratio gives the
weight that could be lifted for given power with the air density
available at ground level. It is given as 0.509, or about 2 to 1 for
power in watts required to lift a weight in grams.
This is at ground level. The thrust available becomes proportionally
less as the air density decreases so you arrange your trajectory so
that most of the powered flight occurs in the lower atmosphere. Lifter
thrust ratios at this level or better have already been demonstrated
for small test cases.
Here's a case where 185g weight of the lifter plus payload was lifted
using 200 watts of power. This is about a 1 to 1 ratio:

Saviour, the WINNER OF THE 100g of PAYLOAD CHALLENGE.
http://jlnlabs.imars.com/lifters/100gwin/index.htm

The next step is to test that this thrust ratio will hold at the
kilowatt range. Many people already own electrical generators that can
put out a few kilowatts of power. They are used for example for
generators for RV's, stand-by generators, picnic trips, etc.
This page shows such generators can be had for a few hundred dollars:

Electric Generator Store - Portable Generator, Diesel Generators ...
http://www.electricgeneratorstore.com/

For example using the 1 to 1 thruster ratio, the 3250 watt generator
advertised for $500 could lift 3.25 kilos, about 7 pounds.


Bob Clark

Sun May 22, 2005 5:07 pm   

N:dlzc D:aol T:com (dlzc) wrote:

I agree the calculation does not include the effect of drag. It would
probably be analogous to the drag encountered by air-breathing methods
of space access, hypersonic craft for instance.
Rockets are efficient but you have the problem of the huge amount of
fuel mass they have to carry. At the very least lifters could provide a
low cost lower stage that could lift the craft to high altitude and to
high velocity before a final rocket stage carried the craft to orbit.
This would result in signficant levels of fuel savings.


Bob Clark

Mon May 23, 2005 1:37 am   

N:dlzc D:aol T:com (dlzc) wrote:

Leik Myrabo et.al. are investigating this type of "ionized air" drive
as a supplement to their beamed laser propulsion method:

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/servlet/GetabsServlet?prog=normal&id=APCPCS000702000001000430000001

Experimental investigation of 2-D ion mobility endoatmospheric drive
(IMED).
U. Filiba, L. N. Myrabo, and H. T. Nagamatsu (Rensselaer Polytechnic
Inst., Troy, NY)
AIAA-2001-3667
AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit, 37th, Salt
Lake City, UT, July 8-11, 2001
http://www.aiaa.org/content.cfm?pageid=406&gTable=mtgpaper&gID=21851


The "endoatmospheric ion-propulsion" engine is clearly the same thing
as the lifter drive.


Bob Clark