Author Topic: EM Drive Developments - related to space flight applications - Thread 3  (Read 1803071 times)

Online Rodal

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I thought I would chime in with questions for the AIAA conference. I am going to be attending the event, so I will be able to report back to you guys about what happens, other questions that were asked, etc.
Let me know of a couple of definite questions that anyone would want me to ask during the Q and A,
AIAA Propulsion and Energy Forum and Exposition
Hilton Orlando, Orlando, Florida...
TUESDAY, JULY 28, 2015  NFF-04. Future Flight Propulsion Systems  ...5:00 PM - 5:30 PM
Direct Thrust Measurements of an EMDrive and Evaluation of Possible Side-Effects Martin Tajmar

Suggested questions to Prof. Tajmar arranged in order of importance:


Q1. What is the explanation for the very low Q (only 50) in your EM Drive experiments?.  Shawyer has reported Q=45,000 for his Demonstrator at your same tested frequency of 2.45 GHz. Is it because you did not use the usual waveguide isolator and 3-stub tuner between the magnetron and test article?

Has Prof. Tajmar's team grossly over-coupled the RF input to the EM Drive copper truncated cone?  Over-coupling is a matter of putting a larger resistive load on the resonant cavity by shunting more of the source load onto the cavity. Over-coupling can give  an "equivalent" bandwidth which includes more than one mode.

Was Tajmar trying to match it w/ ~ 50 MHz  ? How wide was the high filament current magnetron bandwidth?.

_____________________________________________________

Q2. why your experiments show approximately 60% different thrust force measurements when the EM Drive was physically rotated 180 degrees from the "forward" thrust tests to the "reverse" thrust tests?  Shouldn't the thrust be the same regardless of space orientation?  Is this orientation-dependence indicative of an experimental artifact or a dependence on an external field ?

_____________________________________________________


Q3. Does Prof. Tajmar think that the reason why Shawyer and Yang claimed much higher thrust (over 1,000 to 10,000 times greater force/InputPower than what Tajmar measured) is because Shawyer and Yang reported tests at ambient pressure (unlike Prof. Tajmar who has performed his tests in a vacuum), and Shawyer and Yang just reported thermal convection artifacts? If, not a nullification due to Shawyer and Yang not performing tests in vacuum, what does Prof. Tajmar think that the huge difference (1,000 to 10,000 times) is due to ?

_____________________________________________________

Q4:  What does Prof. Tajmar think about the "motor", "generator" conjecture of Shawyer?: that the EM Drive will not register a significant acceleration unless motivated to do so by vibrations of unspecified magnitude and frequency to produce initial acceleration in the direction pointing from the big base to the small base.  Does Prof. Tajmar think that the reason why he measured much lower thrust is because he didn't vibrate the EM Drive to provide such initial condition?

Sorry for the major delay. Was out enjoying a nice weekend vacation with my family. :)

I'll be sure to ask at least the first question. If I have the opportunity to ask more, that would be even better.

I'll be covering the event and doing updates on /r/EmDrive just because it is easier to do on mobile.

-I

I wrote those questions before the paper was released, based on information from knowledgeable sources (apparently the information I got was good).  Upon reading the final paper, I would move this question up, as questions 2 and 3 are pretty much answered in the paper:

Q4Q1:  What does Prof. Tajmar think about the "motor", "generator" conjecture of Shawyer?: that the EM Drive will not register a significant acceleration unless motivated to do so by vibrations of unspecified magnitude and frequency to produce initial acceleration in the direction pointing from the big base to the small base.  Does Prof. Tajmar think that the reason why he measured much lower thrust in vacuum is because he didn't vibrate the EM Drive to provide such initial condition?  Could this also be a reason as to the variability in experimental results ?
« Last Edit: 07/26/2015 12:50 PM by Rodal »

Offline flux_capacitor

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And there's our answer! Look at TM01 mode graph. Since they normalized to Z0, (Eta), then c=1. This graph clearly shows that the group velocity for small kr is faster than light. Likewise, the TE11 mode gives the phase velocity as slower than light for small kr.

Given the thrust to power ratio F/P = 1/v_phase. Then for small kr, there is an enormous thrust for very little power!

This is over my head, please ELI5 what is the physical meaning of a "small kr"? Geometrically, does a "small kr" belongs to a particular region of a continuously- tapered waveguide? The apex maybe?

We now understand that the group velocity exponentially decreases while approaching the small end (for a closed frustum, and if the cavity is properly designed as if it had a "cut-off diameter"). But you also says that group velocity becomes superluminal for small kr in TM01 mode, so what is the dependence between the two?

Online Rodal

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And there's our answer! Look at TM01 mode graph. Since they normalized to Z0, (Eta), then c=1. This graph clearly shows that the group velocity for small kr is faster than light. Likewise, the TE11 mode gives the phase velocity as slower than light for small kr.

Given the thrust to power ratio F/P = 1/v_phase. Then for small kr, there is an enormous thrust for very little power!

This is over my head, please ELI5 what is the physical meaning of a "small kr"? Geometrically, does a "small kr" belongs to a particular region of a continuously- tapered waveguide? The apex maybe?

We now understand that the group velocity exponentially decreases while approaching the small end (for a closed frustum, and if the cavity is properly designed as if it had a "cut-off diameter"). But you also says that group velocity becomes superluminal for small kr in TM01 mode, so what is the dependence between the two?

It is not "kr" but it is a product of two variables: k times r:  k * r , where:


r is the spherical radius: the distance from the apex of the cone.



k is the wavenumber (https://en.wikipedia.org/wiki/Wavenumber) k = 2 Pi/wavelength,

k * r is the dimensionless distance from the apex of the cone, non-dimensionalized by k, since r has units of length and k has units of 1/length

k * r = 0 is the apex of the cone, since r=0 is the apex of the cone
« Last Edit: 07/26/2015 12:21 PM by Rodal »

Offline flux_capacitor

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And there's our answer! Look at TM01 mode graph. Since they normalized to Z0, (Eta), then c=1. This graph clearly shows that the group velocity for small kr is faster than light. Likewise, the TE11 mode gives the phase velocity as slower than light for small kr.

Given the thrust to power ratio F/P = 1/v_phase. Then for small kr, there is an enormous thrust for very little power!

This is over my head, please ELI5 what is the physical meaning of a "small kr"? Geometrically, does a "small kr" belongs to a particular region of a continuously- tapered waveguide? The apex maybe?

We now understand that the group velocity exponentially decreases while approaching the small end (for a closed frustum, and if the cavity is properly designed as if it had a "cut-off diameter"). But you also says that group velocity becomes superluminal for small kr in TM01 mode, so what is the dependence between the two?

It is not kr but k times r:  k * r , where:


r is the spherical radius: the distance from the apex of the cone.

k is the wavenumber (https://en.wikipedia.org/wiki/Wavenumber) k = 2 Pi/wavelength,

k * r is the dimensionless distance from the apex of the cone, non-dimensionalized by k

k * r = 0 is the apex of the cone, since r=0 is the apex of the cone

Thanks Doc! But something still puzzles me: how can group velocity gradually decrease while travelling from a larger cross-section region to a smaller cross-section region (so, towards the apex) but could become superluminal (at TM01 mode according to @WarpTech) near the apex (= small kr)? This is a contradiction to me.

EDIT: I didn't understand kr was actually k * r
So it depends on frequency besides distance from the apex.
« Last Edit: 07/26/2015 12:25 PM by flux_capacitor »

Offline TheTraveller

Being careful to not copy and paste from copyrighted papers behind paywalls.

The Tajmar paper makes a powerful statement as to why the cavity Q dropped from 48.8 to 20.3 during the tests. After internal inspection it was found the cavity internal surfaces had oxidised.

Shawyer recommended to me that all the cavity internal surfaces should be polished to a mirror like finish and be scratch / ding free. To protect that finish from oxidisation, my cavity will be airtight (2 Silicone space rated low outgassing O rings at each end) and to be filled with N2 at 1/2 atmo pressure to stop oxidisation of the internal surfaces.

What this says to me is Shawyer's recommendation for a highly polished is spot on and Tajmar's observations about oxidised internal cavity surfaces reducing Q over 50% are both very valid points to be considered by DIY cavity makers who desire to have their EMDrive's Q as high as possible.

BTW I'm surprised the Tajmar Q is a high as it is, considering the opening size of the WR340 waveguide is 86 x 43mm, 3,698mm area. Frustum side wall area 10,064.2 mm and the hole in the side wall for the waveguide is ~37% of the total. So maybe a Q of 48.8 is not that bad.
« Last Edit: 07/26/2015 12:25 PM by TheTraveller »
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Online Rodal

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...
BTW I'm surprised the Tajmar Q is a high as it is, considering the opening size of the WR340 waveguide is 86 x 43mm, 3,698mm area. Frustum side wall area 10,064.2 mm and the hole in the side wall for the waveguide is ~37% of the total. So maybe a Q of 48.8 is not that bad.
Now put those thoughts together concerning the natural frequency:  2.45 GHz is NOT a subharmonic response it is the natural frequency of this device, as calculated by COMSOL Finite Element analysis.

For the same reason you are discussing above: 

<<the opening size of the WR340 waveguide is 86 x 43mm, 3,698mm area. Frustum side wall area 10,064.2 mm and the hole in the side wall for the waveguide is ~37% of the total. >>

you canNOT use a formula for a close, perfect truncated cone to calculate the natural frequency of this device.  The huge hole lowers the natural frequency of TE111 from over 4 GHz to 2.45 GHz.

Do a back of the envelope analysis and you will see.

This is why CERN and other particle accelerators use FEA to calculate natural frequencies for open cavities.  Once you have a hole in the cavity that represents 37% of the total , of course the natural frequency is going to be much lower than calculated ignoring the hole.

Not a subharmonic response, it is the natural frequency of the cavity taking into account the huge hole from the side waveguide.

If you don't believe it, please consult particle accelerator literature, where cavities with huge holes are common.
« Last Edit: 07/26/2015 12:41 PM by Rodal »

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EDIT: I didn't understand kr was actually k * r
So it depends on frequency besides distance from the apex.
I agree, when I first saw the notation kr in Yang and Fan's paper I found that confusing too, as it could be interpreted as k sub r, a variable instead of two variables multiplied by each other.  I don't like the notation kr.  It would be better if the multiplication sign would be included or if big separation would be included to make it clear that it is the product of two variables, one of the variables (k) dependent on wavelength, and hence dependent on frequency.
« Last Edit: 07/26/2015 12:33 PM by Rodal »

Offline flux_capacitor

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EDIT: I didn't understand kr was actually k * r
So it depends on frequency besides distance from the apex.
I agree, when I first saw the notation kr in Yang and Fan's paper I found that confusing too, as it could be interpreted as k sub r, a variable instead of two variables multiplied by each other.  I don't like the notation kr.  It would be better if the multiplication sign would be included or if big separation would be included to make it clear that it is the product of two variables, one of the variables (k) dependent on wavelength, and hence dependent on frequency.

I concur. Following this idea: since k = 2 Pi/wavelength

A small k implies a longer wavelength so a lower frequency.

A small k*r is dimensionless but implies both a low operating frequency and a short distance from the apex

In a closed cavity there are two ways of getting closer to the apex:
1- Increase the cone angle so the apex is closer to the small end plate
or
2- Make the end plate as smaller as possible

Since we saw Yang's design with a low cone angle is more efficient, we should not try (1) but (2). Which is difficult since the lower the frequency, the bigger the frustum.

Am I right on this?

But how the group velocity can become superluminal while it decreases approaching the apex is still beyond me.

PS: in a tapered waveguide the wavelength naturally varies along its propagation. It is longer near the smaller cross-section region, so k naturally decreases toward the small end.
« Last Edit: 07/26/2015 01:19 PM by flux_capacitor »

Online Rodal

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EDIT: I didn't understand kr was actually k * r
So it depends on frequency besides distance from the apex.
I agree, when I first saw the notation kr in Yang and Fan's paper I found that confusing too, as it could be interpreted as k sub r, a variable instead of two variables multiplied by each other.  I don't like the notation kr.  It would be better if the multiplication sign would be included or if big separation would be included to make it clear that it is the product of two variables, one of the variables (k) dependent on wavelength, and hence dependent on frequency.

I concur. Following this idea: since k = 2 Pi/wavelength

A small k implies a longer wavelength so a lower frequency.

A small k*r is dimensionless but implies both a low operating frequency and a short distance from the apex

In a closed cavity there are two ways of getting closer to the apex:
1- Increase the cone angle so the apex is closer to the small end plate
or
2- Make the end plate as smaller as possible

Since we saw Yang's design with a low cone angle is more efficient, we should not try (1) but (2). Which is difficult since the lower the frequency, the bigger the frustum.

Am I right on this?

But how the group velocity can become superluminal while it decreases is still beyond me.
It should be explored, but until a theory is corroborated to explain the anomalous thrust, what is optimal will not be known

EDIT: but yes, getting closer to the apex is interesting, that's why I wrote the paper about the fact that strong cut-off doesn't apply to conical cavities.  Getting close to the apex brings up General Relativity and other interesting things into the picture.  However, getting close to the apex may also affect the Q.  It needs to be tested
« Last Edit: 07/26/2015 12:55 PM by Rodal »

Offline TheTraveller

...
BTW I'm surprised the Tajmar Q is a high as it is, considering the opening size of the WR340 waveguide is 86 x 43mm, 3,698mm area. Frustum side wall area 10,064.2 mm and the hole in the side wall for the waveguide is ~37% of the total. So maybe a Q of 48.8 is not that bad.
Now put those thoughts together concerning the natural frequency:  2.45 GHz is NOT a subharmonic response it is the natural frequency of this device, as calculated by COMSOL Finite Element analysis.

For the same reason you are discussing above: 

<<the opening size of the WR340 waveguide is 86 x 43mm, 3,698mm area. Frustum side wall area 10,064.2 mm and the hole in the side wall for the waveguide is ~37% of the total. >>

you canNOT use a formula for a close, perfect truncated cone to calculate the natural frequency of this device.  The huge hole lowers the natural frequency of TE111 from over 4 GHz to 2.45 GHz.

Do a back of the envelope analysis and you will see.

This is why CERN and other particle accelerators use FEA to calculate natural frequencies for open cavities.  Once you have a hole in the cavity that represents 37% of the total surface of the cavity, of course the natural frequency is going to be much lower than calculated ignoring the hole.

Not a subharmonic response, it is the natural frequency of the cavity taking into account the huge hole from the side waveguide.

If you don't believe it, please consult particle accelerator literature, where cavities with huge holes are common.

Looking at the side image, it appears the WR40 waveguide is attached to the magnetron but then drops down in size through 2 other smaller then smaller waveguide sections as the cavity side wall is not 86mm long.

Suspect there may be an iris between one of the waveguide to waveguide couplings. Probably at the coupling nearest to the cavity side entrance. Also expect to see some impedance tuning screws as Shawyer told me he has never heard of a successful EMDrive build without having the ability to tune for impedance matching.
"As for me, I am tormented with an everlasting itch for things remote. I love to sail forbidden seas.”
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Offline TheTraveller

...
BTW I'm surprised the Tajmar Q is a high as it is, considering the opening size of the WR340 waveguide is 86 x 43mm, 3,698mm area. Frustum side wall area 10,064.2 mm and the hole in the side wall for the waveguide is ~37% of the total. So maybe a Q of 48.8 is not that bad.
Now put those thoughts together concerning the natural frequency:  2.45 GHz is NOT a subharmonic response it is the natural frequency of this device, as calculated by COMSOL Finite Element analysis.

For the same reason you are discussing above: 

<<the opening size of the WR340 waveguide is 86 x 43mm, 3,698mm area. Frustum side wall area 10,064.2 mm and the hole in the side wall for the waveguide is ~37% of the total. >>

you canNOT use a formula for a close, perfect truncated cone to calculate the natural frequency of this device.  The huge hole lowers the natural frequency of TE111 from over 4 GHz to 2.45 GHz.

Do a back of the envelope analysis and you will see.

This is why CERN and other particle accelerators use FEA to calculate natural frequencies for open cavities.  Once you have a hole in the cavity that represents 37% of the total surface of the cavity, of course the natural frequency is going to be much lower than calculated ignoring the hole.

Not a subharmonic response, it is the natural frequency of the cavity taking into account the huge hole from the side waveguide.

If you don't believe it, please consult particle accelerator literature, where cavities with huge holes are common.

Looking at the side image, it appears the WR40 waveguide is attached to the magnetron but then drops down in size through 2 other smaller then smaller waveguide sections as the cavity side wall is not 86mm long.

Suspect there may be an iris between one of the waveguide to waveguide couplings. Probably at the coupling nearest to the cavity side entrance. Also expect to see some impedance tuning screws as Shawyer told me he has never heard of a successful EMDrive build without having the ability to tune for impedance matching.
Both the CAD image and the COMSOL image (most important, as this was used for analyis of natural frequency purposes) show a big opening instead of an Iris.  The COMSOL FEA analysis was modeled as if there is a huge opening, not an Iris. They would not have gone through the time and expense of doing the COMSOL analysis based on a wrong model of the opening.

Also, and most important, the COMSOL FEA analysis shows the distortion of the electromagnetic field due to the huge opening for the waveguide at the right

That image is copyrighted and behind a paywall. As per Chris's request it should not be posted.

I suspect the iris may be at the right side of the smallest entry waveguide, which would not impact the COMSOL image. Additionally the 3 dropping in size waveguides feeding the cavity will alter the guide wavelength entering the cavity.

The attached might help to shine some light and shows the small end adjustable retraction depth as used on the small end of the Tajmar cavity to tune for highest Q.
« Last Edit: 07/26/2015 01:17 PM by TheTraveller »
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Online Rodal

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The request referred to your posting of a link to  another website that was breaking the copyright of the paper so that people could access the paper without paying.  I referred to a single image to clarify a technical issue for aerospace research purposes.  I never broke any copyrights, I purchased my own copy of the paper (as the AIAA can verify). The image is used to answer an aerospace research question under the Fair Use principle.  I am shocked by your pontificating attitude on this issue, when 1) I was addressing a technical issue that you brought up (incorrectly saying that there is an Iris) and 2) you are the one that posted a link to a copyright infringement place.
Have a good day.
« Last Edit: 07/26/2015 01:42 PM by Rodal »

Offline DrBagelBites

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I wrote those questions before the paper was released, based on information from knowledgeable sources (apparently the information I got was good).  Upon reading the final paper, I would move this question up, as questions 2 and 3 are pretty much answered in the paper:

Q4Q1:  What does Prof. Tajmar think about the "motor", "generator" conjecture of Shawyer?: that the EM Drive will not register a significant acceleration unless motivated to do so by vibrations of unspecified magnitude and frequency to produce initial acceleration in the direction pointing from the big base to the small base.  Does Prof. Tajmar think that the reason why he measured much lower thrust in vacuum is because he didn't vibrate the EM Drive to provide such initial condition?  Could this also be a reason as to the variability in experimental results ?

Ah, my mistake. I replied to you before I read the paper. I agree, those questions were answered.

Will keep everyone posted on Prof. Tajmar's response to the "motor"," generator" question.



Online Rodal

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As in copyright law:

Quote from: Copyright Fair Use
Why are you using the image? If it is “…for purposes such as criticism, comment, news reporting, teaching (including multiple copies for classroom use), scholarship, or research…” you’re on the right track.
.

Amazing that the same person that posted a link to a copyright infringement place is now pontificating on the use of an image to discuss an aerospace research issue, which is a well-known accepted and valid practice.

The liability isn't on your part, it's on Chris Bergin's and NSF's; since the site receives ad revenues, there's a degree of profit that comes from hosting the material on his part, and I'm not sure the thread's intentions of teaching individuals and performing academic study is sufficient to warrant the placement of significant excerpts without NSF inheriting some legal liabilities. Of course, I could be wrong; copyright law and controlling the distribution of information for money is a huge pain in the butt.
Fine, I removed the single image from Tajmar's paper that was used for research purposes to answer a technical question.

I guess that from now on, according to your interpretation, NO more images can be posted "for purposes such as criticism, comment, news reporting, scholarship, or research…" (something which is entirely OK under US Fair Practice Law and has been done in this thread and multiple other threads thousands of times).  I don't think that's what Chris was referring to. That would mean no pictures of space shuttles, or satellites, or Space X, etc, etc., even when full attibution to the author is made and the picture is posted for research purposes to answer a specific question.

Do you see the flagrant difference between posting a single image with attribution to the author, to answer an aerospace research question (something that is explicitly approved under US fair practice law, as I have understood from corporate lawyers)  and posting a link to a copyright infringement place from a foreign country to enable people to access the whole paper without paying (something that is explicitly precluded by law)?
« Last Edit: 07/26/2015 03:23 PM by Rodal »

Offline TheTraveller

As in copyright law:

Quote from: Copyright Fair Use
Why are you using the image? If it is “…for purposes such as criticism, comment, news reporting, teaching (including multiple copies for classroom use), scholarship, or research…” you’re on the right track.
.

Amazing that the same person that posted a link to a copyright infringement place is now pontificating on the use of an image to discuss an aerospace research issue, which is a well-known accepted and valid practice.

The liability isn't on your part, it's on Chris Bergin's and NSF's; since the site receives ad revenues, there's a degree of profit that comes from hosting the material on his part, and I'm not sure the thread's intentions of teaching individuals and performing academic study is sufficient to warrant the placement of significant excerpts without NSF inheriting some legal liabilities. Of course, I could be wrong; copyright law and controlling the distribution of information for money is a huge pain in the butt.
Fine, I removed the single image that was used for research purposes to answer a technical question.

Do you see the flagrant difference between that and this poster that is now pontificating after he posted a link to a copyright infringement place?

The Tajmar paper is no longer behind a paywall.
It is now openly available.
I had no part in that action.
Is easy enough to find and download.
I believed there is sufficient experimental data to warrant all active NSF posters to have the paper.
Have discussed this with Chris and I do apologise for posting the link.

We can't copy and paste images, charts and text from the paper without subjecting NSF to possible copyright actions. To protect NSF and comply with Chris's request, any who have copied and pasted text and images from the paper should remove them ASAP.
« Last Edit: 07/26/2015 01:53 PM by TheTraveller »
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This is legal:

http://fairuse.stanford.edu/overview/fair-use/what-is-fair-use/

This is not:

Linking to a leaked full copy on a known copyright infringement website knowingly circumventing payment of membership fees.

Rodal is engaging in fair use.

/tangent
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Offline TheTraveller

Training your Dragon or Tuning your EmDrive

Prof Yang's team when through 3 stages to tune their cavity to get a final unloaded Q of 117,500.

1st they made 7 Big and 7 Small end caps with different retraction lengths, Then tried all 49 combinations to find the combo that generated the highest Q. Best combo was 4mm retraction for the Big end and 12mm retraction for the Small end. Best Q was then 977.

Next they tried many combinations of the iris with the best Q occurring with an iris opening size of L1 = 43.34 mm, L2 = 31.78 mm for the rectangular microwave coupling window. Max Q increased to 1,512.

Finally the 2 impedance matching screws were adjusted to get max Q 117,500.

Sound easy when the process is laid out and explained.
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Offline flux_capacitor

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Gentlemen, you have a considerable audience here, more interested in EmDrive developments related to space flight applications. Please settle this issue via PM. You are both two very valuable persons, and I enjoy reading your thoughts most of the time when they are not against one's behavior. Science needs you two.

Another matter. Today I wrote a clarification on Physics Stack Exchange about group velocity in a waveguide and momentum transmission, which is different than electromagnetic waves propagating in free space.
If you think the content there has worth, please go to the post, read it and upvote :)
If you think it is incomplete or false, comments are of course welcome:
http://physics.stackexchange.com/questions/190018/does-radiation-force-depend-on-group-velocity-or-on-phase-velocity/196014#196014

I've commented on this mainly because what was stated previously on Wikipedia about phase velocity in a waveguide (which is superluminal) was IMO false.

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Gentlemen, you have a considerable audience here, more interested in EmDrive developments related to space flight applications. Please settle this issue via PM. You are both two very valuable persons, and I enjoy reading your thoughts most of the time when they are not against one's behavior. Science needs you two.

Another matter. Today I wrote a clarification on Physics Stack Exchange about group velocity in a waveguide and momentum transmission, which is different than electromagnetic waves propagating in free space.
If you think the content there has worth, please go to the post, read it and upvote :)
If you think it is incomplete or false, comments are of course welcome:
http://physics.stackexchange.com/questions/190018/does-radiation-force-depend-on-group-velocity-or-on-phase-velocity/196014#196014

I've commented on this mainly because what was stated previously on Wikipedia about phase velocity in a waveguide (which is superluminal) was IMO false.
I'll read it in a bit but I want to air an observation that has shaken the foundations of what I thought I knew and accepted for years. For years I thought evanescent waves were kind of a numerical aberration of a waveform and carried no ability to do work, this has been proven wrong. I was also taught that actions could supersede light, they can. I was also taught that a group velocity couldn't cause any effects, this is also becoming untrue. So many things I thought I knew are being overturned and questioned by some of the new physics. And you know... I like it!

Offline RERT

Guys -

This is several steps ahead of ourselves, but may be of interest, especially to The Traveller.

The data posted here on the Drude model confirmed that the relaxation time was, within a constant, how I had modelled it as mentioned to in a recent post. I was able to calculate with some confidence the relaxation time of Silver and Copper. The time for silver is much larger than for copper (about 50% bigger). Conductivity is also a notch better with Silver.

It occurred to me that if we had thrust measurements for frustrums with:

1. Copper at each end
2. Copper at the large end and silver at the small end
3. Silver at the small end and copper at the large end
4. Silver at each end

Then we might see the effects of these material changes, if they exist, in thrust changes.

I believe The Traveller has said that he will be silver/gold plating components of his many Frustrums. Having many frustrums in different states of plating, it seems like this is something which might be testable along the way.

Another thought related to recent posts is that all of these tests could be carried out at constant Q by using the 'impedance matching screws' (whatever they are!) to de-tune the better cavities to the Q of the worst.

Thrust anomalies which depended only on the electrical characteristics of the materials inside the frustrum
might provide a challenge to sceptics.

That said, if The Traveller's program works, sceptics will already be in retreat....

R.


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