Author Topic: EM Drive Developments - related to space flight applications - Thread 3  (Read 1798915 times)

Offline SeeShells

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Aero: do you have any gaps through which evanescent waves can escape? when you had an evanescent wave field in the past, was it achieved through intentional gaps you had placed on purpose?

No, there are no gaps, as is evident in the code snippet posted above.
Yes, in the past my frustum was modelled as perfect metal, hence intentional gaps were the only method to allow evanescent waves to escape. I did model the Copper Kettle with perfect metal and the gasket they had used at one point. See image attached. I don't remember anything more about that gasket, but it did make a pretty picture  :)

If there are no gaps, and (assuming that Meep is not modeling any quantum tunneling and/or that the walls are too thick for quantum tunneling to take place) then the asymmetric Poynting vector in the model must be getting dissipated into the copper (eventually resulting into heat).  Currents are magnetically induced in the walls by the electromagnetic field, and these currents will meet resistance (eventually dissipating) energy into heat.

Is there a way to look into the current into the walls in Meep ?
I'm not sure how meep can or would model Evanescent EM waves. I'm sure they use it for light but...  How about a simple test to see if we can see a EM evanescent waves form with meep. A thin piece of copper ~2um thick with a 2.45GHz dipole on one side  ~.12 m X and Y at a 12 to even 45 degree reflective angle and the dipole parallel 1/4 wave from the copper sheet.
What do you think?

Offline Rodal

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I don't know if there is the same issue here because I haven't read the forum in a while, but there seems to be a bit of a misconception on the Poynting vector and what it indicates over on the reddit forum.

Alot of people seem to have confused the idea of a net, non-zero time averaged poynting vector with a net thrust.  ...

A net poynting vector, even averaged over all time, is NOT indicative of a net force.  Force is the rate of change of the poynting vector, so a constant force would have to come from a monotonically increasing poynting vector, such that at any given time step we would need to see a poynting vector greater than the time step before.

I want to stress this point because this is something I've personally stumbled over too many times.

It sounds like the people in the other forum are confused and your post would be helpful over there. 

One important point in general, though is that the time-averaged (over an integer number of periods) of the Poynting vector divided by the speed of light in free space is the radiation pressure exerted by an electromagnetic wave on the surface of a target, if the wave is completely absorbed by the target .

Stress = <Poynting vector averaged over integer number of periods> / c

this formula has been verified experimentally multiple times since 1900 when the wave is absorbed by the target, and it can be elementary obtained from the contravariant component of the Stress-Energy tensor in 3+1 General Relativity:

« Last Edit: 07/03/2015 11:52 PM by Rodal »

Offline Rodal

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Aero: do you have any gaps through which evanescent waves can escape? when you had an evanescent wave field in the past, was it achieved through intentional gaps you had placed on purpose?

No, there are no gaps, as is evident in the code snippet posted above.
Yes, in the past my frustum was modelled as perfect metal, hence intentional gaps were the only method to allow evanescent waves to escape. I did model the Copper Kettle with perfect metal and the gasket they had used at one point. See image attached. I don't remember anything more about that gasket, but it did make a pretty picture  :)

If there are no gaps, and (assuming that Meep is not modeling any quantum tunneling and/or that the walls are too thick for quantum tunneling to take place) then the asymmetric Poynting vector in the model must be getting dissipated into the copper (eventually resulting into heat).  Currents are magnetically induced in the walls by the electromagnetic field, and these currents will meet resistance (eventually dissipating) energy into heat.

Is there a way to look into the current into the walls in Meep ?
I'm not sure how meep can or would model Evanescent EM waves. I'm sure they use it for light but...  How about a simple test to see if we can see a EM evanescent waves form with meep. A thin piece of copper ~2um thick with a 2.45GHz dipole on one side  ~.12 m X and Y at a 12 to even 45 degree reflective angle and the dipole parallel 1/4 wave from the copper sheet.
What do you think?

Analysis of evanescent fiber optic sensors using Meep as a simulation tool

http://www.researchgate.net/publication/262955603_Analysis_of_evanescent_fiber_optic_sensors_using_Meep_as_a_simulation_tool

Bloch Modes and Evanescent Modes of Photonic Crystals
http://www.mdpi.com/2073-4352/5/1/14/pdf
« Last Edit: 07/04/2015 12:03 AM by Rodal »

Offline WarpTech

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Aero: do you have any gaps through which evanescent waves can escape? when you had an evanescent wave field in the past, was it achieved through intentional gaps you had placed on purpose?

No, there are no gaps, as is evident in the code snippet posted above.
Yes, in the past my frustum was modelled as perfect metal, hence intentional gaps were the only method to allow evanescent waves to escape. I did model the Copper Kettle with perfect metal and the gasket they had used at one point. See image attached. I don't remember anything more about that gasket, but it did make a pretty picture  :)

If there are no gaps, and (assuming that Meep is not modeling any quantum tunneling and/or that the walls are too thick for quantum tunneling to take place) then the asymmetric Poynting vector in the model must be getting dissipated into the copper (eventually resulting into heat).  Currents are magnetically induced in the walls by the electromagnetic field, and these currents will meet resistance (eventually dissipating) energy into heat.

Is there a way to look into the current into the walls in Meep ?
I'm not sure how meep can or would model Evanescent EM waves. I'm sure they use it for light but...  How about a simple test to see if we can see a EM evanescent waves form with meep. A thin piece of copper ~2um thick with a 2.45GHz dipole on one side  ~.12 m X and Y at a 12 to even 45 degree reflective angle and the dipole parallel 1/4 wave from the copper sheet.
What do you think?

We are seeing evanescent waves in these images! The power diminishes (exponentially?) as the waves move from front to back. After each reflection, the poynting vectors that hit the wall give up some momentum to the frustum pushing it forward, and redirect themselves more toward the x direction. After each bounce, the vector loses momentum and energy due to heat from copper losses. The less energy and momentum it has when it arrives at the big end plate, and the lowest angle of incidence that can be achieved, the more thrust will be harnessed. Makes me think that "Brass" used by Juan Yang may be better than copper. It's resistivity is 5x higher, and a superconductor may not work as well. Based on this, longer and less taper is better, but I have not calculated an optimum design factor yet.
Todd

Offline SeeShells

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Aero: do you have any gaps through which evanescent waves can escape? when you had an evanescent wave field in the past, was it achieved through intentional gaps you had placed on purpose?

No, there are no gaps, as is evident in the code snippet posted above.
Yes, in the past my frustum was modelled as perfect metal, hence intentional gaps were the only method to allow evanescent waves to escape. I did model the Copper Kettle with perfect metal and the gasket they had used at one point. See image attached. I don't remember anything more about that gasket, but it did make a pretty picture  :)

If there are no gaps, and (assuming that Meep is not modeling any quantum tunneling and/or that the walls are too thick for quantum tunneling to take place) then the asymmetric Poynting vector in the model must be getting dissipated into the copper (eventually resulting into heat).  Currents are magnetically induced in the walls by the electromagnetic field, and these currents will meet resistance (eventually dissipating) energy into heat.

Is there a way to look into the current into the walls in Meep ?
I'm not sure how meep can or would model Evanescent EM waves. I'm sure they use it for light but...  How about a simple test to see if we can see a EM evanescent waves form with meep. A thin piece of copper ~2um thick with a 2.45GHz dipole on one side  ~.12 m X and Y at a 12 to even 45 degree reflective angle and the dipole parallel 1/4 wave from the copper sheet.
What do you think?

Analysis of evanescent fiber optic sensors using Meep as a simulation tool

http://www.researchgate.net/publication/262955603_Analysis_of_evanescent_fiber_optic_sensors_using_Meep_as_a_simulation_tool

Bloch Modes and Evanescent Modes of Photonic Crystals
http://www.mdpi.com/2073-4352/5/1/14/pdf
I asked because there seems so little on Meep with Microwaves and Evanescent waves.
https://en.wikipedia.org/wiki/Comparison_of_EM_simulation_software
https://en.wikipedia.org/wiki/Comparison_of_EM_simulation_software

Offline Rodal

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Here are the Poynting Vector fields for the COPPER model and the Meep METAL models

I don't see any appreciable difference between them (at the only time step for which a csv file is available for the METAL model, the last time step)

Offline demofsky

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.....

Makes me think that "Brass" used by Juan Yang may be better than copper. It's resistivity is 5x higher, and a superconductor may not work as well. Based on this, longer and less taper is better, but I have not calculated an optimum design factor yet.
Todd

So is the meep "Perfect Conductor" a reasonable facsimile for a superconductor for our purposes?  Or would we be missing important effects, particularly magnetic?  Doing a run with brass as the material would also be useful to confirm Warptech's hypothesis. 

(And oh man are we cooking!)

Offline SeeShells

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Aero: do you have any gaps through which evanescent waves can escape? when you had an evanescent wave field in the past, was it achieved through intentional gaps you had placed on purpose?

No, there are no gaps, as is evident in the code snippet posted above.
Yes, in the past my frustum was modelled as perfect metal, hence intentional gaps were the only method to allow evanescent waves to escape. I did model the Copper Kettle with perfect metal and the gasket they had used at one point. See image attached. I don't remember anything more about that gasket, but it did make a pretty picture  :)

If there are no gaps, and (assuming that Meep is not modeling any quantum tunneling and/or that the walls are too thick for quantum tunneling to take place) then the asymmetric Poynting vector in the model must be getting dissipated into the copper (eventually resulting into heat).  Currents are magnetically induced in the walls by the electromagnetic field, and these currents will meet resistance (eventually dissipating) energy into heat.

Is there a way to look into the current into the walls in Meep ?
I'm not sure how meep can or would model Evanescent EM waves. I'm sure they use it for light but...  How about a simple test to see if we can see a EM evanescent waves form with meep. A thin piece of copper ~2um thick with a 2.45GHz dipole on one side  ~.12 m X and Y at a 12 to even 45 degree reflective angle and the dipole parallel 1/4 wave from the copper sheet.
What do you think?

Analysis of evanescent fiber optic sensors using Meep as a simulation tool

http://www.researchgate.net/publication/262955603_Analysis_of_evanescent_fiber_optic_sensors_using_Meep_as_a_simulation_tool

Bloch Modes and Evanescent Modes of Photonic Crystals
http://www.mdpi.com/2073-4352/5/1/14/pdf
I asked because there seems so little on Meep with Microwaves and Evanescent waves.
https://en.wikipedia.org/wiki/Comparison_of_EM_simulation_software
https://en.wikipedia.org/wiki/Comparison_of_EM_simulation_software

Adding something...
https://en.wikipedia.org/wiki/Comparison_of_EM_simulation_software
Edit...EDIT 2013-01-10: I am convinced the problem is really in PML being able to amplify the evanescent waves in the near field of the oscillator. I tried to put a thin highly lossy medium into part of the PML volume. The propagating waves are attenuated enough by PML and do not reflect. The evanescent waves which freely pervade the PML are now attenuated in the lossy medium and the simulation is eventually stable.

There is one caveat: when the evanescent waves get attenuated, most of the resonances in the structure become damped. With the lossy medium or without it, one has to provide enough space around the structure if the narrow resonances are to be simulated properly! Otherwise it makes no sense to run a long simulation anyway.

I have also observed the case when losses and amplification nearly cancelled out and the resonances became narrow even in a small volume. However, generally it is much more practical to allocate a great simulation volume than to fine tune the losses in PML! It would be interesting if a evanescent-wave-friendly PML could be coded in MEEP in the future.

Offline SeeShells

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Aero: do you have any gaps through which evanescent waves can escape? when you had an evanescent wave field in the past, was it achieved through intentional gaps you had placed on purpose?

No, there are no gaps, as is evident in the code snippet posted above.
Yes, in the past my frustum was modelled as perfect metal, hence intentional gaps were the only method to allow evanescent waves to escape. I did model the Copper Kettle with perfect metal and the gasket they had used at one point. See image attached. I don't remember anything more about that gasket, but it did make a pretty picture  :)

If there are no gaps, and (assuming that Meep is not modeling any quantum tunneling and/or that the walls are too thick for quantum tunneling to take place) then the asymmetric Poynting vector in the model must be getting dissipated into the copper (eventually resulting into heat).  Currents are magnetically induced in the walls by the electromagnetic field, and these currents will meet resistance (eventually dissipating) energy into heat.

Is there a way to look into the current into the walls in Meep ?
I'm not sure how meep can or would model Evanescent EM waves. I'm sure they use it for light but...  How about a simple test to see if we can see a EM evanescent waves form with meep. A thin piece of copper ~2um thick with a 2.45GHz dipole on one side  ~.12 m X and Y at a 12 to even 45 degree reflective angle and the dipole parallel 1/4 wave from the copper sheet.
What do you think?

Analysis of evanescent fiber optic sensors using Meep as a simulation tool

http://www.researchgate.net/publication/262955603_Analysis_of_evanescent_fiber_optic_sensors_using_Meep_as_a_simulation_tool

Bloch Modes and Evanescent Modes of Photonic Crystals
http://www.mdpi.com/2073-4352/5/1/14/pdf
I asked because there seems so little on Meep with Microwaves and Evanescent waves.
https://en.wikipedia.org/wiki/Comparison_of_EM_simulation_software
https://en.wikipedia.org/wiki/Comparison_of_EM_simulation_software

Adding something...

Edit...EDIT 2013-01-10: I am convinced the problem is really in PML being able to amplify the evanescent waves in the near field of the oscillator. I tried to put a thin highly lossy medium into part of the PML volume. The propagating waves are attenuated enough by PML and do not reflect. The evanescent waves which freely pervade the PML are now attenuated in the lossy medium and the simulation is eventually stable.

There is one caveat: when the evanescent waves get attenuated, most of the resonances in the structure become damped. With the lossy medium or without it, one has to provide enough space around the structure if the narrow resonances are to be simulated properly! Otherwise it makes no sense to run a long simulation anyway.

I have also observed the case when losses and amplification nearly cancelled out and the resonances became narrow even in a small volume. However, generally it is much more practical to allocate a great simulation volume than to fine tune the losses in PML! It would be interesting if a evanescent-wave-friendly PML could be coded in MEEP in the future.

Aero, there seems to be some different modes that correct issues with this maybe it would be wise to look at the mods.
https://en.wikipedia.org/wiki/Comparison_of_EM_simulation_software

Offline TheTraveller

My Files.

Here are my files, which include every attachment (image, Pdf, Doc) Paul March uploaded to NSF.

There are a few SPR documents included which are not on their web site.

One very important document is the Cullen 1951 paper (in the SPR and Chinese folder). Good to review section 2.1 as it contains Cullen's equation 15, which is very much the base of Shawyer's theory as to how the momentum transfer of a EM wave, bouncing off an end plate, constrained in a microwave cavity varies as the guide wavelength varies as per the waveguide diameter, excitation mode and external Rf wavelength.

https://drive.google.com/folderview?id=0B7kgKijo-p0ifk9EakZfbW9aZGMwNWZMQ01xVnBON0tkM2w0Q1NLbmtjRFFwMXBuNVlVN0U&usp=sharing
« Last Edit: 07/04/2015 01:24 AM 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 TheTraveller

My Files.

Here are my files, which include every attachment (image, Pdf, Doc) Paul March uploaded to NSF.

There are a few SPR documents included which are not on their web site.

One very important document is the Cullen 1951 paper (in the SPR and Chinese folder). Good to review section 2.1 as it contains Cullen's equation 15, which is very much the base of Shawyer's theory as to how the momentum transfer of a EM wave, bouncing off an end plate, constrained in a microwave cavity varies as the guide wavelength varies as per the waveguide diameter, excitation mode and external Rf wavelength.

https://drive.google.com/folderview?id=0B7kgKijo-p0ifk9EakZfbW9aZGMwNWZMQ01xVnBON0tkM2w0Q1NLbmtjRFFwMXBuNVlVN0U&usp=sharing
<< which is very much the base of Shawyer's theory as to how the momentum transfer of a EM wave, bouncing off an end plate, constrained in a microwave cavity >>

That's an incorrect statement.  It is clear from Dr. Cullen's paper that his Ph.D. thesis (and the paper you referenced, which contains part of his thesis) dealt with waveguides and not with closed cavities.

I was astonished to find out that Shawyer refers to Cullen's paper to defend his theory for a closed cavity, as it is clear from Dr. Cullen's paper that the formula he uses is vaiid for an open waveguide.

Furthermore this is in no way "Cullen's formula", this is Maxwell's formula, as Cullen himself points out.  Since some people have difficulty understanding Maxwell, Cullen pointed out in his paper to an easier, more intuitive derivation (done by somebody else much prior to Cullen, as Cullen points out) than Maxwell's derivation.

Boy have you got that wrong.

The guide wavelength inside a waveguide doesn't change if you close the waveguide.  A frustum is a variable diameter waveguide. Such diameter adapters are used in the microwave industry all the time.

Instead of having the end plates at the ends of the variable diameter section, you could extend them out say 1m and then put on the end plates. Would still work.

So imagine 150mm dia end cap, 1m of 150mm diameter waveguide, a 250mm long, 150mm to 280mm diameter adapter and then 1m of 280mm diameter waveguide, finished off with a 280mm dia end cap.
« Last Edit: 07/04/2015 01:47 AM 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 TheTraveller

...
Boy have you got that wrong.

The guide wavelength inside a waveguide doesn't change if you close the waveguide.  A frustum is a variable diameter waveguide. Such diameter adapters are used in the microwave industry all the time.

Boy is it evident that you have never read Cullen's paper.

I have read it many times.

Bottom line is Shawyer is right and you are wrong.

Closing a waveguide will not alter the guide wavelength, so your argument is invalid but I think you do know that.
"As for me, I am tormented with an everlasting itch for things remote. I love to sail forbidden seas.”
Herman Melville, Moby Dick

Offline TheTraveller

...
Bottom line is Shawyer is right and you are wrong.

Closing a waveguide will not alter the guide wavelength, so your argument is invalid but I think you do know that.
Bottom line is that ALL your posts are about promoting Shawyer.

I'm promoting the TRUTH.

ALL your posts are to discredit Shawyer. Not very scientific old chap.

Point was about the guide wavelength not altering when you close the waveguide. Which it does not. Therefore Cullen's equation 15 is valid for a closed waveguide and Shawyer's use of it is valid.

You know that is correct yet you will never stop trying to discredit Shawyer. Do you have some vested interest in discrediting Shawyer or is it you made a mistake and can't walk away from it?
"As for me, I am tormented with an everlasting itch for things remote. I love to sail forbidden seas.”
Herman Melville, Moby Dick

Offline aero

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Rodal and Traveler - Do we have a "Don't like" button on this forum or is that the Moderator's job?
Retired, working interesting problems

Offline TheTraveller

Rodal and Traveler - Do we have a "Don't like" button on this forum or is that the Moderator's job?

Rodal made a clearly incorrect statement about Cullen 15 not being valid for closed waveguides and attached Shawyer for using it.
I showed him he was incorrect.
Knowing I was correct he then attached me for promoting Shawyer, instead of answering my rebuttal.

When someone attacks me, I will defend myself.
« Last Edit: 07/04/2015 02:12 AM 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 Rodal

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REVIEW OF A.L. Cullen's "Absolute Power Measurement at Microwave Frequencies" in reference to TheTraveller's comments

ABSOLUTE POWER MEASUREMENT AT MICROWAVE FREQUENCIES
By A. L. CULLEN, Ph.D., B.Sc.(Eng.), Associate Member.
(published February, 1952.)

For a copy of Cullen's paper, click here:  http://forum.nasaspaceflight.com/index.php?action=dlattach;topic=36313.0;attach=828862

This paper has been referenced by Mr. Shawyer in a number of his papers and presentations on the theory and practice of the EM Drive operation.

As Cullen himself writes, the purpose of Cullen's paper was to describe the techniques adopted for his Ph.D. thesis experiments (at the University of London) and to explain their theoretical basis.

It is apparent, upon reading Cullen's paper, that:

1) No truncated cone (fustrum of a cone, as in Shawyer's EM Drive) of any kind was used in Cullen's experiments or ever discussed in Cullen's paper from a theoretical viewpoint. Cullen used constant (through their length) cross-section waveguides.  One waveguide had a rectangular cross-section and another waveguide had a circular cross-section.

2) No summation of forces for microwaves inside a closed cavity truncated cone (fustrum of a cone, as in Shawyer's EM Drive) are ever discussed in Cullen's paper.

3) No Einstein’s law of addition of velocities or relativistic frames for the beam and the waveguide are used or discussed in Cullen's paper.

4) The cylindrical waveguide used in Cullen's experiment for radiation pressure measurement was not a closed-cavity with all internal surfaces reflective (as in the EM Drive) but was instead a cylindrical waveguide with transparent glass as one of its ends (transparent glass which deliberately allowed the microwave beam to enter the cylindrical waveguide and also allowed the reflected waves to escape the cylindrical waveguide so that only travelling waves would hit the other end of the waveguide for pressure measurements).

5) The expressions that Cullen uses to calculate the pressure (including Cullen's Eq. 15) were first derived by Maxwell (the diagonal component of Maxwell's stress tensor).  Cullen uses the more intuitive, physical derivation of J.J. Thompson.  Cullen never pretends that these are his equations and he makes it clear that he is following Thompson's derivation.

______________
Cullen's article has a number of useful observations:

A) It was impossible to obtain a stable baseline, even on a relatively short-term basis of a minute's duration.  This continual drifting of the baseline was found to be due to air convection currents set up by small and changing temperature gradients within the microwave waveguides.  The remedy was to reduce the air resistance of the reflecting end plate so that the convection currents would have no appreciable effect.  The reflecting end plate was replaced by a system of concentric wire rings (shown on Fig. 12 of Cullen's paper).  The rings acted as an almost perfect reflector of the electromagnetic waves but at the same time had a small effective cross-section to air currents.  NASA, Shawyer, Yang, and other EM Drive researchers would be well advised to experiment with replacing the end plates of the EM Drive with this system of concentric rings, in order to address the problem of air convection currents that has plagued radiation pressure experiments in ambient conditions ever since Maxwell 140 years ago.

B) Cullen used a rectangular waveguide to direct the radiation. To prevent subsequent radiation from the reflector the waveguide was terminated with a matched load, such that there was no reflection of the incident wave.  A T-junction was used for transmission to a piston (a cylindrical waveguide with one end made of transparent glass and the other end capped by a reflector), without reflection into the main guide.

C) Standing wave measurements were separately performed with a closed cavity and movable (micrometer) end plate to assess the purity of mode TM01 in the waveguides, to make sure that resonance at other modes (mainly TM21) was not significant.

« Last Edit: 07/04/2015 03:49 AM by Rodal »

Offline ThinkerX

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Traveler - Not attacking, just pointing something out.

In my book, Shawyer gets major points.  Best I can tell, the conical Frustum EM Drive thing is his concept.  He spent a lot of years trying to figure things out, building one experimental model after another.   In some areas, he was clearly ahead of the curve - I used to make comments to this effect in prior versions of this thread.

Lately, though, what I see are grand claims lacking substance - most of them coming from you.  Grand claims, to be taken seriously, REQUIRE grand evidence.  A new theory or model won't suffice here.  To back these claims up, to have them taken seriously, Shawyer will need to cough up a truly impressive EM Demo model - one that can be replicated by others. Talking about something that can lift itself, or dang close to it.

At this point, your relentless promotions are hurting Shawyer's case far more than you are helping it. 

Offline SeeShells

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I posted this the other day on reddit and I'm not sure who saw it there and it's true there as here.

As of today I'm aware of around 15 published tests that have observed a pressure or some call it thrust when the drive is powered. It seems to me that the reality of the device to produce an thrust or better a "push" in one direction is out of the noise of experimental error. http://emdrive.wiki/Experimental_Results
There are currently (that we know of) around 10 different theories as to why this works. http://emdrive.wiki/Theory
This is in reality not much different than the theories on explaining black holes, dark energy, dark mass, quantum entanglement, string theories, how standard physics links to the world of quantum effects, even the simple unaccounted forces accounting for the spin on a proton can't be found, the list goes on.
This is science. All we know and can say with conviction is we don't know. We need data to plug into these theories and even Einstein's theory E=Mc2 is continuing to garner data to it's validity.
I have my own prize pets in why it does what it does and they don't quite violate anything but I'll not be a fool and say nothing is impossible until verified, tested and we have data shooting out our arses. Data we can plug into the theories to see how the real word data we collect matches the theories and who knows maybe a whole new theory will evolve not related to anyones.
To this point I'll not argue CoE or Com or Maxwell's violation theories or try to discredit anyone attempt at a theory. I simply don't have enough data to say you're wrong and anyone who says they do just might be proven wrong somewhere down the line.
I'm just going to wait and gather information from the dozen or so builders to see where it leads. http://emdrive.wiki/Building
We are such imperfect creatures trying our damndest to see a perfectly assembled universe of quarks, gluons, vectored forces of energy, time and matter and those imperfections show in our theories in how it all works.
The only thing that is solid is data and to that point it's what the dirty dozen DIYers are trying to do. Even TheTraveler is trying, although he has faced some ridicule in his support of controversial theories from Shawyer. I too have been criticised on my build as most are/have/will be and it's no big deal.
Don't you just love science?
« Last Edit: 07/04/2015 03:07 AM by SeeShells »

Offline Rodal

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I attach below a comparison of the Poynting vector field for the zCopper model from @aero with the Copper and the Metal models (for the last time step). It is apparent that the Poynting vector field of the zCopper model is weaker.

QUESTION: what is the difference between the zCopper model and the Copper and Metal models that makes the Poynting vector for the zCopper model weaker?

It is important to understand this difference, as whatever the zCopper model invoves, it looks that is not the way to go to maximize the Poynting vector field. Better to avoid it.

This is the explanation I found:

Quote from: aero
It had never dawned on me that the x on Ex was the direction of the current. I have been alligning my Ez source antenna in the y direction thinking that in the real world, it couldn't matter. But maybe in the numerical model world? I changed direction of the antenna in the NSF-1701 copper model to the z direction, still using Ez as the source current and made a resonance run in Meep.

The antenna direction does not change the resonant frequency but it increased the quality factor Q, by 40 times.

I have since ran and uploaded the full set of .csv files, naming them zCopper .csv to differentiate them from the previously named Copper .csv files. They appear to have much larger numbers than before. You may wish to look at them.

It looks like this increase in Q resulting from the different orientation of the antenna (z instead of y) is counterproductive

It looks like it is better to align the antenna in the y direction with Ez as the source current than aligning the antenna in the z direction with Ez as the source current.
« Last Edit: 07/04/2015 03:35 AM by Rodal »

Offline aero

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The difference between the Metal and the Copper model is perfect metal and our model of copper material. The difference between the Copper and zCopper model is the orientation of the dipole antenna. Both (all 3) models are excited by an Ez source. The Copper model antenna is aligned parallel to the y-axis while the zCopper model antenna is aligned parallel to the z-axis. That is it. Performance wise, the zCopper model gave a meep calculated quality factor ~40 times higher than the already high quality factor of the copper model, and over 10 times higher than the Metal model.

If the Poynting vector field is weaker, doesn't this tell us something? I wonder if the Metal model Poynting vector field is intermediate because the Medal model Q was intermediate.
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