Author Topic: EM Drive Developments - related to space flight applications - Thread 3  (Read 1876296 times)

Offline Rodal

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...
From work on my spreadsheet, that can easily adopt to various TMm,n and TEm,n modes, I believe it is possible to get an excitation mode that will deliver a high Df, small end operating just above cutoff (as Shawyer recommends), without using stupid geometry...
This fact should be more important than what a spreadsheet may predict:

Using a DesignFactor ~ 1 results in a Shawyer-formula predicted thrust output

Force = (2 * Power * Q * Df) /c
         = (2 * Power * Q ) /c       for Df =1

for the Demonstrator at the maximum power tested of 1200 Watts and Q = 45000 and  c= 299705000 m/s (speed of light in air) gives

360 milliNewtons

that's 3.5 times the maximum thrust (102 milliNewtons) reported  for the Demonstrator, so something is amiss with the spreadsheet calculation or with the data reported by Shawyer.
« Last Edit: 05/28/2015 04:14 PM by Rodal »

Offline tchernik

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I'm just gonna leave this here...

"Macroscopic and Direct Light Propulsion of Bulk Graphene Material"
http://arxiv.org/ftp/arxiv/papers/1505/1505.04254.pdf


Quote
The force generated from such a process/mechanism is much
larger than the force generated directly from the conventional light pressure, which is
much smaller than the force required to propel the samples.

Quote
The mechanism behind this novel phenomenon is believed to be an
efficient light-induced ejected electron emission process, following an Auger-like path
due to both the unique band structure of graphene and its macroscopic morphology of
this unique material.

While a very interesting discovery and potential  development all in itself, this graphene sponge sail would provide thrust in fully explainable ways.

By accelerating and ejecting electrons due to the material physical properties and thus, getting a reaction, it would still be a conventional rocket engine. The graphene sponge lightsail will eventually need to replenish its electrons in order to continue providing thrust.

The advantage of this is that electrons are aplenty in the vicinity of the Sun, thanks to the solar wind. Therefore I imagine an electrodynamic tether could be used to replenish the electrons on a sail like this, allowing it to continue working almost anywhere in the Solar System.

Not sure if the same would apply for trans-neptunian space or interstellar missions, though.

Offline TheTraveller

...
From work on my spreadsheet, that can easily adopt to various TMm,n and TEm,n modes, I believe it is possible to get an excitation mode that will deliver a high Df, small end operating just above cutoff (as Shawyer recommends), without using stupid geometry...
As you said that you care much more about experimental reports of thrust forces than about what a theory may predict, then this fact should be more important than what a spreadsheet may predict:

Using a DesignFactor ~ 1 results in a Shawyer-formula predicted thrust output

Force = (2 * Power * Q * Df) /c
         = (2 * Power * Q ) /c       for Df =1

for the Demonstrator at the maximum power tested of 1200 Watts and Q = 45000 and  c= 299705000 m/s (speed of light in air) gives

360 milliNewtons

that's 3.5 times the maximum thrust (102 milliNewtons) reported  for the Demonstrator, so something is amiss with your spreadsheet calculation or with the data reported by Shawyer.

Apologies if you misunderstood me.

Theory of HOW it works is fine as that helps to predicts device operational parameters.

Theory of WHY it works, well that is not involved in building hardware.

Shawyer didn't report thrust at 1.2kWs. The only reported thrust was 96mN at 334W. Also reported was the maximum specific thrust of 214mN/kW over 134 test runs.
« Last Edit: 05/28/2015 04:09 PM by TheTraveller »
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Offline Rodal

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I changed the wording  :)

Offline txdrive

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@Rodal

Apologies, but I thought that there'd already been some tests done in a vacume chamber with this device while still producing apparent thrust.  Was I mistaken on this?

If not, I would think that heated air convection would no longer be considered a potential factor in this device.
The only organization, to my knowledge, that has reported tests in vacuum is NASA Eagleworks.

Although Shawyer has been reporting tests for about 15 years and NPWU in China for several years, they have not reported tests in vacuum, to my knowledge.

Since the tests results by NASA in vacuum were lower than the test results in air, it very much looks like the hypothesis that there is a significant thermal "gas effect" component involved in the tests is very much still alive, particularly when considering the much higher power used by Shawyer and NPWU in China.

There is noting I have seen from the researchers that quantifies the size of this "gas effect" in the experiments conducted in air in the UK and China.  Moreover, none of these tests have been conducted with a mesh for the ends, which is the only way that Cullen (who Shawyer uses as his main reference) found to eliminate the gas effect when performing tests in air in his 1951 Ph.D. thesis (the first time that anyone was able to quantitatively measure radiation pressure due to microwaves).

That a significant gas effect component is present would not be surprising as it has been known since Maxwell in the 1870's that scientists trying to measure radiation pressure (at microwave and higher frequencies) have had to deal with such problems for over 100 years (these problems are collectively known as "the gas effect").
Rather than using vacuum or a mesh, it'd be preferable if they enclosed everything in an air-tight box that was suspended to make it insensitive to changes in centre of mass.

Keep in mind also that (with Shawyer's formula) the net thrust may be stronger than a photon rocket but it is no stronger than a mirror (and with mirrors it is well known that effects due to heating are very huge comparing to pressure, unless very special conditions apply).

Regarding the EagleWorks results (let's not tarnish NASA's reputation as a whole, please, with what most certainly will turn out to be a dud), their thrust is much less than predicted by Shawyer's formula, thus constituting a falsification.

Shawyer's mistaken calculations of radiation pressure are not just theoretically wrong, they have been experimentally falsified by EagleWorks.

Eagleworks also obtained no thrust without plastic inside the cavity, or when the plastic was not firmly in contact with the cavity wall, which would decrease heat conduction into the plastic but not affect EM fields otherwise. edit: I do not have the reference right now but I believe March had posted that when a plastic screw melted, the drive performance decreased.

Now with regards to EagleWorks and their far smaller forces which don't replicate when turned around by 180 degrees: Their interpretation that it is a sum of some classical forces they don't understand with some anomalous novel physics they are discovering... well it leaves much to be desired. If they were quantifying their errors better they'd simply have something like 50uN 100uN : a falsification of Shawyer's theory, and a multitude of classical forces that are known to arise at such power levels limiting the precision of said falsification. It took very smart people a long time to fully understand Crookes radiometer.

edit: Throw in a couple tensioned leaf springs, heated by electrical current, some plastic the edges of which may be decomposing (strong electric field at a discontinuity in dielectric constant), plastic screws literally melting. Put it onto a non-vertical pendulum that is sensitive to shifts in centre of mass. Non-null findings of some kind (due to classical physics)  are then guaranteed, and they're guaranteed to be very difficult to understand.

edit: CoM -> centre of mass, due to use of CoM to mean "conservation of momentum".
« Last Edit: 05/30/2015 01:39 AM by txdrive »

Offline TheTraveller

Flight Thruster build update:

From the best photo of the Flight Thruster I could find and allowing for 2mm thick walls, to add thermal mass and reduce the rate of thermal expansion, the following internal Flight Thruster dimensions were obtained:

Length:   138.6mm
Small diameter:   125.7mm
Big diameter:   231.4mm

Applying those to my spreadsheet generated:

Df:   0.638
Frequency:   3.85GHz
Mode:   TE013

I then asked Roger Shawyer did I get close? His reply:

Df:  0.635
Frequency:   3.9003GHz
Mode:   TE013

I'm VERY happy with that as my Rf gen can easily go to that frequency. Time now to finalise drawings and get some copper sheet laser cut.

Roger also mentioned it is best to give the internal frustum surfaces a nice bright shinny polish. No need for Silver or Gold overcoats.
« Last Edit: 05/28/2015 05:20 PM by TheTraveller »
"As for me, I am tormented with an everlasting itch for things remote. I love to sail forbidden seas.
Herman Melville, Moby Dick

Offline MyronQG

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@Rodal

Apologies, but I thought that there'd already been some tests done in a vacume chamber with this device while still producing apparent thrust.  Was I mistaken on this?

If not, I would think that heated air convection would no longer be considered a potential factor in this device.
The only organization, to my knowledge, that has reported tests in vacuum is NASA Eagleworks.

Although Shawyer has been reporting tests for about 15 years and NPWU in China for several years, they have not reported tests in vacuum, to my knowledge.

Since the tests results by NASA in vacuum were lower than the test results in air, it very much looks like the hypothesis that there is a significant thermal "gas effect" component involved in the tests is very much still alive, particularly when considering the much higher power used by Shawyer and NPWU in China.

There is noting I have seen from the researchers that quantifies the size of this "gas effect" in the experiments conducted in air in the UK and China.  Moreover, none of these tests have been conducted with a mesh for the ends, which is the only way that Cullen (who Shawyer uses as his main reference) found to eliminate the gas effect when performing tests in air in his 1951 Ph.D. thesis (the first time that anyone was able to quantitatively measure radiation pressure due to microwaves).

That a significant gas effect component is present would not be surprising as it has been known since Maxwell in the 1870's that scientists trying to measure radiation pressure (at microwave and higher frequencies) have had to deal with such problems for over 100 years (these problems are collectively known as "the gas effect").
Rather than using vacuum or a mesh, it'd be preferable if they enclosed everything in an air-tight box that was suspended to make it insensitive to changes in centre of mass.

Keep in mind also that (with Shawyer's formula) the net thrust may be stronger than a photon rocket but it is no stronger than a mirror (and with mirrors it is well known that effects due to heating are very huge comparing to pressure, unless very special conditions apply).

Regarding the EagleWorks results (let's not tarnish NASA's reputation as a whole, please, with what most certainly will turn out to be a dud), their thrust is much less than predicted by Shawyer's formula, thus constituting a falsification.

Shawyer's mistaken calculations of radiation pressure are not just theoretically wrong, they have been experimentally falsified by EagleWorks.

Eagleworks also obtained no thrust without plastic inside the cavity, or when the plastic was not firmly in contact with the cavity wall, which would decrease heat conduction into the plastic but not affect EM fields otherwise.

Now with regards to EagleWorks and their far smaller forces which don't replicate when turned around by 180 degrees: Their interpretation that it is a sum of some classical forces they don't understand with some anomalous novel physics they are discovering... well it leaves much to be desired. If they were quantifying their errors better they'd simply have something like 50uN 100uN : a falsification of Shawyer's theory, and a multitude of classical forces that are known to arise at such power levels limiting the precision of said falsification. It took very smart people a long time to fully understand Crookes radiometer.

edit: Throw in a couple tensioned leaf springs, heated by electrical current, some plastic the edges of which may be decomposing (strong electric field at a discontinuity in dielectric constant), plastic screws literally melting. Put it onto a non-vertical pendulum that is sensitive to shifts in CoM. Non-null findings of some kind are then guaranteed, and they're guaranteed to be very difficult to understand.

I fully agrre with this viewpoint. Bottom line is: the EMdrive cannot work according to the presently accepted theoretical framework in propulsion science, unless a strong deviation from nearly flat spacetime is induced in its surroundings, which could easily be detected by sensitive enough accelerometers. If you want to half-convince people that it really works (before going to full-fledged orbit control demonstration), just put the whole device (test article + power supply + wirings + etc.) onto the thrust sensing rig, in a so to speak "closed system" configuration, and operate it under high vacuum conditions. It is also advisable to always measure thrust by optical means to minimize EMI on the measurement electronics, to run tests using "dummy" equivalent electrical loads with the same input power and to run tests with the reaL thing but with the sensing rig "tight-locked" to quantify readings coming from mundane causes.

Online aero

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I'm just gonna leave this here...

"Macroscopic and Direct Light Propulsion of Bulk Graphene Material"
http://arxiv.org/ftp/arxiv/papers/1505/1505.04254.pdf


Quote
The force generated from such a process/mechanism is much
larger than the force generated directly from the conventional light pressure, which is
much smaller than the force required to propel the samples.


Quote
The mechanism behind this novel phenomenon is believed to be an
efficient light-induced ejected electron emission process, following an Auger-like path
due to both the unique band structure of graphene and its macroscopic morphology of
this unique material.


Wow! Forces orders of magnitude greater than photon pressure of the illuminating laser - due to electron emmission.
Retired, working interesting problems

Offline RERT

Err...I don't know if this is a lightbulb moment or a senior moment, but if the cavity generates an asymmetrical pattern of eddy currents in the surface of the frustrum, wouldn't that interact with the Earth's magnetic field to produce a net force?

Offline TheTraveller

Flight Thruster build update:

From the best photo of the Flight Thruster I could find and allowing for 2mm thick walls, to add thermal mass and reduce the rate of thermal expansion, the following internal Flight Thruster dimensions were obtained:

Length:   138.6mm
Small diameter:   125.7mm
Big diameter:   231.4mm

Applying those to my spreadsheet generated:

Df:   0.638
Frequency:   3.85GHz
Mode:   TE013

I then asked Roger Shawyer did I get close? His reply:

Df:  0.635
Frequency:   3.9003GHz
Mode:   TE013

I'm VERY happy with that as my Rf gen can easily go to that frequency. Time now to finalise drawings and get some copper sheet laser cut.

Roger also mentioned it is best to give the internal frustum surfaces a nice bright shinny polish. No need for Silver or Gold overcoats.

Using the following dimensions:

Length:   138.6mm
Small diameter:   125.7mm
Big diameter:   231.4mm

and using the speed of light in air:

cAir = 299705000 (meter/s)

My exact solution gives:

Mode:   TE013
Frequency:   3.94571 GHz

The results data I received from Roger was from the SPR inhouse EM Drive design & development software suite.
"As for me, I am tormented with an everlasting itch for things remote. I love to sail forbidden seas.
Herman Melville, Moby Dick

Offline MyronQG

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I'm just gonna leave this here...

"Macroscopic and Direct Light Propulsion of Bulk Graphene Material"
http://arxiv.org/ftp/arxiv/papers/1505/1505.04254.pdf


Quote
The force generated from such a process/mechanism is much
larger than the force generated directly from the conventional light pressure, which is
much smaller than the force required to propel the samples.


Quote
The mechanism behind this novel phenomenon is believed to be an
efficient light-induced ejected electron emission process, following an Auger-like path
due to both the unique band structure of graphene and its macroscopic morphology of
this unique material.


Wow! Forces orders of magnitude greater than photon pressure of the illuminating laser - due to electron emmission.

What about the growing positive charge that develops on the thruster? It seems there will be necessary to inject protons into the electron jet to maintain neutrality of charge.

Offline sfrank

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This says the imbalance on just the end plates is 100X more significant than those on the sidewalls. So my thought experiment is optimizing that end of it, so to speak.  ;D


...

Maybe we should setup a listing of the proposed theories/conjectures we got so far and how we could experimentally test them individually? if they fail, you can scrap the theory and move to the next one...

I accept the challenge!  http://emdrive.echothis.com/List_of_Suggested_Experiments
I'm going to work backwards through the threads.  It will take me awhile to get everything listed.  If you have a particular idea you'd like listed, just pm it to me and I'll add it immediately.

Offline TheTraveller

Flight Thruster build update:

From the best photo of the Flight Thruster I could find and allowing for 2mm thick walls, to add thermal mass and reduce the rate of thermal expansion, the following internal Flight Thruster dimensions were obtained:

Length:   138.6mm
Small diameter:   125.7mm
Big diameter:   231.4mm

Applying those to my spreadsheet generated:

Df:   0.638
Frequency:   3.85GHz
Mode:   TE013

I then asked Roger Shawyer did I get close? His reply:

Df:  0.635
Frequency:   3.9003GHz
Mode:   TE013

I'm VERY happy with that as my Rf gen can easily go to that frequency. Time now to finalise drawings and get some copper sheet laser cut.

Roger also mentioned it is best to give the internal frustum surfaces a nice bright shinny polish. No need for Silver or Gold overcoats.

Using the following dimensions:

Length:   138.6mm
Small diameter:   125.7mm
Big diameter:   231.4mm

and using the speed of light in air:

cAir = 299705000 (meter/s)

My exact solution gives:

Mode:   TE013
Frequency:   3.94571 GHz

The results data I received from Roger was from the SPR inhouse EM Drive design & development software suite.

WARNING

It looks like you are aiming for a degenerate natural frequency  as this Transverse Magnetic mode has the same natural frequency:

TM113

as TE013

Using coax to feed in the Rf, you need very different antenna and physical antenna placement points to excite either TM or TE mode.

So not an issue.
« Last Edit: 05/28/2015 05:55 PM by TheTraveller »
"As for me, I am tormented with an everlasting itch for things remote. I love to sail forbidden seas.
Herman Melville, Moby Dick

Online aero

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I'm just gonna leave this here...

"Macroscopic and Direct Light Propulsion of Bulk Graphene Material"
http://arxiv.org/ftp/arxiv/papers/1505/1505.04254.pdf


Quote
The force generated from such a process/mechanism is much
larger than the force generated directly from the conventional light pressure, which is
much smaller than the force required to propel the samples.


Quote
The mechanism behind this novel phenomenon is believed to be an
efficient light-induced ejected electron emission process, following an Auger-like path
due to both the unique band structure of graphene and its macroscopic morphology of
this unique material.


Wow! Forces orders of magnitude greater than photon pressure of the illuminating laser - due to electron emmission.

What about the growing positive charge that develops on the thruster? It seems there will be necessary to inject protons into the electron jet to maintain neutrality of charge.

Yes, that's always a problem with ion engines, and this electron engine would have a similar problem. But it could be that illuminating this device with onboard diode lasers could act to neuralize the charge buildup on an ion engine at a much lower mass penalty. This material was like 10 kg/m3 if my conversion was correct, and a cubic meter seems way more than would be needed.

I'm not familiar with the neutralizing techniques used on ion engines or the mass of the neutralizing system but almost any conventional hardware is going to necessarily be more massive. The down side is that a system using this graphene foam might be physically large which, due to structure, would negate any mass advantage of the material.

But enough of that, I don't see how this relates to the EM drive ... but it is a very interesting phenomon by itself and the paper is very readable giving detailed experimental results. I wish we could get the same detailed experimental results from the EM drive work.

Maybe from The Traveller - Mulletron - SeeShell (if she bulids one) - or one of several others to numerous to mention.  Do we have a list anywhere of all of the DIY efforts ongoing or planned?
« Last Edit: 05/28/2015 06:14 PM by aero »
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Offline sfrank

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...

Maybe from The Traveller - Mulletron - SeeShell (if she bulids one) - or one of several others to numerous to mention.  Do we have a list anywhere of all of the DIY efforts ongoing or planned?

http://emdrive.echothis.com/Building

9 listed so far!  Once they really get going we can make individual wiki pages for tracking each person's tests. I have a feeling at some point in the next few months we'll be innundated with experimental results.
« Last Edit: 05/28/2015 06:27 PM by sfrank »

Offline SeeShells

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Maybe from The Traveller - Mulletron - SeeShell (if she bulids one) - or one of several others to numerous to mention.  Do we have a list anywhere of all of the DIY efforts ongoing or planned?
I am working on building one. I have an idea that I'm still working on that's a little bit different than anything else.  I'm still working out details of the build and design. At my age I can't afford redos or mistakes so I'm slowly working through the details. Not quite ready to release it for peer consumption. Thanks for remembering me, it means someone is listening to my babbling. ;)
Shell 

Offline rfmwguy

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I'm just gonna leave this here...

"Macroscopic and Direct Light Propulsion of Bulk Graphene Material"
http://arxiv.org/ftp/arxiv/papers/1505/1505.04254.pdf


Quote
The force generated from such a process/mechanism is much
larger than the force generated directly from the conventional light pressure, which is
much smaller than the force required to propel the samples.

Quote
The mechanism behind this novel phenomenon is believed to be an
efficient light-induced ejected electron emission process, following an Auger-like path
due to both the unique band structure of graphene and its macroscopic morphology of
this unique material.

Funny you mentioned graphene material...in thread #2 I posted a carbon black (graphene derivative) HDPE dielectric study...regardless, there seems to be something interesting going on...secret sauce?  ;)

"Here's an old Bulgarian Science Foundation paper where an HDPE was studied using MW (2-10 GHz) : ftp://213.176.96.142/sciencedirect48477b28-4072-20141124031119.pdf

Seems they are quite interested in absorption and reflection performance with the introduction of acetylene carbon black (CB) into HDPE. Doncha love mixing  chemistry and electronics?  :D

"It is obvious that the CB concentration influence on the microwave properties is the strongest in the frequency range 23 GHz. At optimum CB concentration (17.5 mass%), the coefficient of attenuation reaches 5 dB/mm,
while the coefficient of reflection is close to the starting HDPE coefficient, i.e., the absorption
activity is more than 10 times greater than the reflection activity.""

Offline JasonAW3

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@Rodal

Apologies, but I thought that there'd already been some tests done in a vacume chamber with this device while still producing apparent thrust.  Was I mistaken on this?

If not, I would think that heated air convection would no longer be considered a potential factor in this device.
The only organization, to my knowledge, that has reported tests in vacuum is NASA Eagleworks.

Although Shawyer has been reporting tests for about 15 years and NPWU in China for several years, they have not reported tests in vacuum, to my knowledge.

Since the tests results by NASA in vacuum were lower than the test results in air, it very much looks like the hypothesis that there is a significant thermal "gas effect" component involved in the tests is very much still alive, particularly when considering the much higher power used by Shawyer and NPWU in China.

There is noting I have seen from the researchers that quantifies the size of this "gas effect" in the experiments conducted in air in the UK and China.  Moreover, none of these tests have been conducted with a mesh for the ends, which is the only way that Cullen (who Shawyer uses as his main reference) found to eliminate the gas effect when performing tests in air in his 1951 Ph.D. thesis (the first time that anyone was able to quantitatively measure radiation pressure due to microwaves).

That a significant gas effect component is present would not be surprising as it has been known since Maxwell in the 1870's that scientists trying to measure radiation pressure (at microwave and higher frequencies) have had to deal with such problems for over 100 years (these problems are collectively known as "the gas effect").

However, there did appear to be thrust effects in the vacume, although much reduced compared to those in atmosphere?

I really wish we had a page we could go to to compare the results of each test in a comparitive fashion.  Dredging through hundreeds of Emails to try to fimnd answers that have already been given, in one form or another, is a real pain.
My God!  It's full of universes!

Offline Flyby

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I accept the challenge!  http://emdrive.echothis.com/List_of_Suggested_Experiments
I'm going to work backwards through the threads.  It will take me awhile to get everything listed.  If you have a particular idea you'd like listed, just pm it to me and I'll add it immediately.

Maybe add R.Shawyer also, as he has build a nitrogen cooled 2nd generation EMdrive, with the intention to increase Q.
His test, if successful, would prove that a higher Q does indeed result in more thrust and consequently send all theories based on attenuation of waves to the bin...

HOPEFULLY, he's prepared to share some more technical/data details... :-\
« Last Edit: 05/28/2015 06:58 PM by Flyby »

Online WarpTech

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This says the imbalance on just the end plates is 100X more significant than those on the sidewalls. So my thought experiment is optimizing that end of it, so to speak.  ;D


On condition of course that it is really the case, wouldn't it make sense then to use "metglas" on the (small?) endplate, because it has a dramatically increased magnetic permeability, compared to copper?(x1000000)
Wouldn't that greatly amplify that magnetic imbalance then?

http://en.wikipedia.org/wiki/Permeability_%28electromagnetism%29

It was talked about some 150 pages ago or so, but it fell between the cracks...

IF we assume that the EMdrive gets validated as a thrust generating device, I think we should try to setup some experimental parameters that will test each of the proposed theories on their validity.
Maybe we should setup a listing of the proposed theories/conjectures we got so far and how we could experimentally test them individually? if they fail, you can scrap the theory and move to the next one...

I would tend to agree, Metglass at the Large end, would increase the thrust. Whether or not it would increase it as much as De Aquino thinks it will, is debatable.

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