Author Topic: EM Drive Developments - related to space flight applications - Thread 3  (Read 1797793 times)

Online Rodal

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I have placed the attached text file in the csv files folder.
I have been working on computing (from your prior csv data that I used to plot the Poynting vector field) the time evolution of the Poynting vector through time.  Ideally, I would like to use a gridpoint along the longitudinal axis of the EM Drive to show this, but in examining your data it has become apparent that your present Finite Difference model mesh does not have Finite Difference grid points along the longitudinal axis of the EM Drive.  The closest grid rows are 132 and 133 that are equidistant from the longitudinal axis of axisymmetry of the cone.  The reason is that you have an even number of equally spaced gridpoint rows (264) in the direction perpendicular to the longitudinal axis.  In the future, if you re-mesh, it would be convenient to have an odd number of gridpoints in the direction perpendicular to the longitudinal axis, so that you have gridpoints located in the longitudinal axis.  This would allow direct computation of field quantities at the longitudinal axis (which many times correspond to a maximum) without having to use interpolation.

Having gridpoints along the longitudinal axis of axisymmetry would also allow to define the antenna directly at longitudinal gridpoints, rather than at gridpoints equdistant from the longitudinal axis.

QUESTION: since you do NOT have any gridpoints along the longitudinal axis, how can the antenna location be defined to be in the longitudinal axis? Everything in Finite Differences gets defined only at FD gridpoints.  Do you have antennas located at equidistant points from the longitudinal axis? (that's what the plots show).

The csv file data shows the antenna on the xz plane with normal y to be located at both rows z=132 and z=133 gridpoints  and at column x=208

Shown below are the Poynting vector x component ( minus sign means direction is towards the big base, plus sign means direction is towards small base)  in the xz plane with normal y, at columns x=207,208 and 209, first zooming at the location of the peak and below are the plots showing the whole, un-zoomed range.

It is important to have grid points along the longitudinal axis, in order to avoid the artifact of two peaks seen at column 207 below, and the flat top (a "mesa") seen at column 208 instead of a peak.
« Last Edit: 07/06/2015 02:47 PM by Rodal »

Offline ElizabethGreene

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That figure alone should be enough to convince you that in general, the Poynting vector can not be reduced to a force.  Clearly there is some difference between a solar sail being "pushed" by the poynting flux from the sun, and the lack of force on a metal sheet caught in the poynting flux of a simple DC circuit.   

Please correct me if I am wrong, but there are forces in your simple DC circuit.  They are real, but tiny due of the infinitesimal amount of current involved.


Schematic diagram of a railgun

Image credit:
https://en.wikipedia.org/wiki/Railgun

(Edited to swap out huge picture for small picture.)
« Last Edit: 07/06/2015 01:40 PM by ElizabethGreene »

Offline ElizabethGreene

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I am a bit afraid about this but I don't think it will be too easy to figure out. I disclosed it and discussed it with a doctor of physics specialized in quantum. He said "I still don't believe it works but I saw it".

I am interested in your thoughts about commercial application. Obviously, Shawyer has a few Patents... But there is a just a handful of investors who could develop this into commercial technology.

Disclose or don't.  Mumbling about it half-secretively is not just non-productive it is anti-productive.  If you are worried about your IP consider that Mr. Shawyer has been shouting his design from the rooftops for a decade, and has, until late last year, had only one (1) nibble.

Online aero

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I have placed the attached text file in the csv files folder.
I have been working on computing (from your prior csv data that I used to plot the Poynting vector field) the time evolution of the Poynting vector through time.  Ideally, I would like to use a gridpoint along the longitudinal axis of the EM Drive to show this, but in examining your data it has become apparent that your present Finite Difference model mesh does not have Finite Difference grid points along the longitudinal axis of the EM Drive.  The closest grid rows are 132 and 133 that are equidistant from the longitudinal axis of axisymmetry of the cone.  The reason is that you have an even number of equally spaced gridpoint rows (264) in the direction perpendicular to the longitudinal axis.  In the future, if you re-mesh, it would be convenient to have an odd number of gridpoints in the direction perpendicular to the longitudinal axis, so that you have gridpoints located in the longitudinal axis.  This would allow direct computation of field quantities at the longitudinal axis (which many times correspond to a maximum) without having to use interpolation.

Having gridpoints along the longitudinal axis of axisymmetry would also allow to define the antenna directly at longitudinal gridpoints, rather than at gridpoints equdistant from the longitudinal axis.

QUESTION: since you do NOT have any gridpoints along the longitudinal axis, how can the antenna location be defined to be in the longitudinal axis? Everything in Finite Differences gets defined only at FD gridpoints.  Do you have antennas located at equidistant points from the longitudinal axis? (that's what the plots show).

The csv file data shows the antenna on the xz plane with normal y to be located at both rows z=132 and z=133 gridpoints  and at column x=208

Shown below are the Poynting vector x component ( minus sign means direction is towards the big base, plus sign means direction is towards small base)  in the xz plane with normal y, at columns x=207,208 and 209, first zooming at the location of the peak and below are the plots showing the whole, un-zoomed range.

It is important to have grid points along the longitudinal axis, in order to avoid the artifact of two peaks seen at column 207 below, and the flat top (a "mesa") seen at column 208 instead of a peak.

I'll see what I can do.

Meep documentation says that Meep uses "pervasive" interpolation, or some word like that. Implying that when a value not on a grid point is needed, weighted average of adjacent points is calculated.
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Online Rodal

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...I'll see what I can do.

Meep documentation says that Meep uses "pervasive" interpolation, or some word like that. Implying that when a value not on a grid point is needed, weighted average of adjacent points is calculated.

Yes, that's what Meep did (interpolation), as I show in the plots above.  But it is not optimal, as I also show what happens at location 207 (double peak).  It is much better to have gridpoints along the longitudinal axis, so if you ever re-mesh I suggest to take the opportunity to have an odd number of rows with gridpoints along the longitudinal axis.  It is only at Finite Difference gridpoints in a Finite Difference solution that one can control the solution (imposing conditions at gridpoints).

« Last Edit: 07/06/2015 03:23 PM by Rodal »

Offline ludkokanta

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There is another

This is the best place to comment so I'll go ahead

AMAP device today measured 22 micro Newtons from 4,5 watt input.

Weighing 500 grams the first protoype is nowhere near its potential.


Online Rodal

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There is another

This is the best place to comment so I'll go ahead

AMAP device today measured 22 micro Newtons from 4,5 watt input.

Weighing 500 grams the first protoype is nowhere near its potential.

Please answer these previously asked questions ( http://forum.nasaspaceflight.com/index.php?topic=37642.msg1400695#msg1400695 ), or your posts are in danger of being declared off topic in this thread:

QUESTION 1: Is the prototype you are discussing an EM Drive (a truncated conical cavity resonating at microwave frequencies) with Space Flight Propulsion applications?

QUESTION 2: Does your working prototype use any propellants to expel as a rocket exhaust and achieve propulsion?

QUESTION 3: Does it operate at microwave frequencies?


Please refer to page 1 of this thread:

<<This is a thread - Thread 3 in the series - focused on objective analysis of whether the EM Drive (a truncated conical cavity resonating at microwave frequencies) reported "thrust force" is an experimental artifact or whether it is a real propulsion effect  that can be used for space applications, and if so, in discussing those possible space propulsion applications.>>

« Last Edit: 07/06/2015 03:55 PM by Rodal »

Offline Stormbringer

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at the risk of appearing to disagree with the direction the thread has been on almost since it's inception; i have to point out that two of those are not definitive of the EM drive phenomenon. They are definitive of the type of EM drive this thread has discussed. That is true. but the thread title is not Shawyer, Yang, Cannae, EW type EM drives. It is EM drives.

Now i am suspicious as the next person when someone makes grand claims but will not show any evidence for it. (About the only thing going for him at the moment is he is from where Tesla came from) But it is entirely possible for there to be an EM drive that is not a truncated cone or pyramid that works at another frequency. :)

I would hope that if someone jumped into the discussion that had another approach they would be welcome ( provided they had a solid case to present.)
« Last Edit: 07/06/2015 04:12 PM by Stormbringer »
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Online Rodal

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at the risk of appearing to disagree with the direction the thread has been on almost since it's inception; i have to point out that two of those are not definitive of the EM drive phenomenon. They are definitive of the type of EM drive this thread has discussed. That is true. but the thread title is not Shawyer, Yang, Cannae, EW type EM drives. It is EM drives.

Now i am suspicious as the next person when someone makes grand claims but will not show any evidence for it. (About the only thing going for him at the moment is he is from where Tesla came from) But it is entirely possible for there to be an EM drive that is not a truncated cone or pyramid that works at another frequency. :)

I would hope that if someone jumped into the discussion that had another approach they would be welcome ( provided they had a solid case to present.)

Please refer to Chris Bergin guidelines and posts on NSF Advanced Concepts and on the EM Drive thread in particular, and the history why this thread was closed in the past.

I agree that we could open the door regarding the shape of the device.  However, we should stay within microwave frequencies, otherwise we loose focus for a thread that is already huge and difficult to search through.   As I said, other threads can be opened on devices that do not operate at the microwave range of frequencies.

« Last Edit: 07/06/2015 04:50 PM by Rodal »

Online Rodal

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did a search and did not find this... hope it was not posted yet
Quote
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
I wonder if someone from this thread could attend the conference and if there is a following Q/A, even mention some of the experiments discussed here, ask questions, etc.

I am looking forward to this presentation.  Unfortunately, I won't be attending.  I have tried to find out, from several different second-hand sources what has been the nature of Martin Tajmar's experiments.  It is my personal understanding that his EM Drive experiments have shown  very low force/InputPower readings for an EM Drive in a partial vacuum: less than a few dozen or so times the force/InputPower of a perfectly collimated photon rocket, thus much lower thrust force/InputPower than Yang (who reported 300,000  times a photon rocket) and Shawyer (25,000 to 70,000 times) have reported.  I understand that the quality factor of resonance (Q) in the experiments is extremely low, much lower than any researcher has reported up to now. 

Regarding possible questions to ask if anybody attends, one suggestion (if this is what is reported) is to ask why is his experimental  Q so low (less than 100): how could the experiments have been conducted under resonance if the Q was so low?. Another question: what was responsible for such a low Q in the experiments, and whether Tajmar thinks that the discrepancy with other researchers has to do with the different Q reported from different researchers.

Another suggested question to Prof. Tajmar: given the very low force/InputPower readings for an EM Drive in a partial vacuum measured by Prof. Tajmar (less than a few dozen or so times the force/InputPower of a perfectly collimated photon rocket),  does Prof. Tajmar see his (and Georg Fiedler's) experiments at The Technische Universitšt Dresden as a scientific nullification of the claims made by Yang  and Shawyer, since Yang and Shawyer claim over 1,000 to 10,000 times greater force/InputPower than what Tajmar measured) ?

Does Prof. Tajmar think that the reason why Shawyer and Yang claimed much higher thrust 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 ?

Another suggested question to ask Tajmar (apparently their experimental measurements at some point showed some 60% orientation dependence if my understanding is correct, not clear whether experimental noise, and whether he will present some updated data):

QUESTION: why did the 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 ?
« Last Edit: 07/06/2015 05:30 PM by Rodal »

Online aero

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...I'll see what I can do.

Meep documentation says that Meep uses "pervasive" interpolation, or some word like that. Implying that when a value not on a grid point is needed, weighted average of adjacent points is calculated.

Yes, that's what Meep did (interpolation), as I show in the plots above.  But it is not optimal, as I also show what happens at location 207 (double peak).  It is much better to have gridpoints along the longitudinal axis, so if you ever re-mesh I suggest to take the opportunity to have an odd number of rows with gridpoints along the longitudinal axis.  It is only at Finite Difference gridpoints in a Finite Difference solution that one can control the solution (imposing conditions at gridpoints).

I seem to have misplaced the h5 files needed to generate the csv files for the case you are interested in, so I'll need to re-run it. Shall I go ahead and recreate and upload the complete data set with a new mesh, or try to match the data that I already used. (I'm a little concerned that I may have changed the antenna length).

Rerunning and uploading the complete data set won't take as much effort as it did the first time because using my new file naming convention I can do it all en-mass, without the need to keep the default identically named .csv files in separate identifying folders.

Your call. I'm leaning toward the latter to avoid any concern about inconsistent data.
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Online Rodal

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...I'll see what I can do.

Meep documentation says that Meep uses "pervasive" interpolation, or some word like that. Implying that when a value not on a grid point is needed, weighted average of adjacent points is calculated.

Yes, that's what Meep did (interpolation), as I show in the plots above.  But it is not optimal, as I also show what happens at location 207 (double peak).  It is much better to have gridpoints along the longitudinal axis, so if you ever re-mesh I suggest to take the opportunity to have an odd number of rows with gridpoints along the longitudinal axis.  It is only at Finite Difference gridpoints in a Finite Difference solution that one can control the solution (imposing conditions at gridpoints).

I seem to have misplaced the h5 files needed to generate the csv files for the case you are interested in, so I'll need to re-run it. Shall I go ahead and recreate and upload the complete data set with a new mesh, or try to match the data that I already used. (I'm a little concerned that I may have changed the antenna length).

Rerunning and uploading the complete data set won't take as much effort as it did the first time because using my new file naming convention I can do it all en-mass, without the need to keep the default identically named .csv files in separate identifying folders.

Your call. I'm leaning toward the latter to avoid any concern about inconsistent data.
I vote for re-running with a slightly different mesh such that it has gridpoints in the longitudinal direction (an odd number of equi-distant rows).   Antenna location the same (near the small end).  Orientation the same (if I recall correctly source was Ez but it was oriented along y ? -please double check).  Copper model.

Offline ludkokanta

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Regarding the question is my device an EM drive...

It doesn't use propellant and can be used to drive space objects.

It is different from the EM drive, however.
Mine is better it appears.

Both are relativity drives, both are a disproof od Newtons third (which is something special relativity should have taught us), both partially "externalize" impulse and reduce sealed system entropy by doing so.

Offline mittelhauser

Regarding the question is my device an EM drive...

It doesn't use propellant and can be used to drive space objects.

It is different from the EM drive, however.
Mine is better it appears.

Both are relativity drives, both are a disproof od Newtons third (which is something special relativity should have taught us), both partially "externalize" impulse and reduce sealed system entropy by doing so.

I'm assuming that English isn't your native language so I am trying to give you some leeway but...

If you aren't willing to provide any details, what is your purpose in posting here?  I'm an active lurker and very much appreciate the signal to noise ration that NSF has maintained.  Completely random claims, with no substantiating data, is definitely NOISE not signal.

The "I need to protect my IP" assertion is not helpful.  If you aren't going to share information, I ask again, why post on NSF?  This is not a place for publicity or fundraising.  Of course, both of those would require information as well.  So, it appears the most likely case is that you are simply a troll.  If you aren't, you need to convince us.

However, it is certainly possible to provide data without revealing IP.  And some public documentation of your efforts would certainly be a good way to go after somebody else if desired down the road. 

But, frankly, count me in the skeptic category.   

Or go get your patents filed and come back once you feel you are covered enough to post something beyond self-congratulatory and unsubstantiated claims...

Offline sfrank

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Regarding the question is my device an EM drive...

It doesn't use propellant and can be used to drive space objects.

It is different from the EM drive, however.
Mine is better it appears.

Both are relativity drives, both are a disproof od Newtons third (which is something special relativity should have taught us), both partially "externalize" impulse and reduce sealed system entropy by doing so.

It strikes me that there are basically two types of people who claim they've invented miracle devices.  You have those like Woodward and Shawyer who fully disclose the concept and their experimental setup and weather the resulting criticism.  Then you have those like then infamous Norman Dean who are secretive about the details of how their device work, and do things like charge people to view his prototype device.  I think its pretty clear why a lot more attention is given to Shawyer and Woodward's devices than to other, secretive claims.

Bottom line, don't be a Dean Drive. Do what you need to with patents, but you're not going to get any interest from the scientific community unless you disclose details that can be tested and verified.
 https://en.wikipedia.org/wiki/Dean_drive

Offline Blaine

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I would like to know what would happen if we were to induce eddy currents by spinning magnets above the EmDrive - like the Hendo hoverboard.  I'll remove the post because I feel its random, but if the EmDrive is interacting with an external field wouldn't this be an interesting experiment?
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Online Rodal

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...
I'll see what I can do.

To plot the time variation of the Poynting vector, I need to know your Finite Difference time step in Meep units of time.

Offline Stormbringer

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I think it is my fault. He started his own thread. I told him it belonged in this thread because his claims fits the generalized EM drive definition. Then his thread disappeared and he was posting in here. Now it appears the thread isn't for generalized EM drives but specifically A narrow subset and mostly for independent confirmation or nullification thereof. So it is my mistake. Solution... maybe he could post  his topic independently again. Maybe a topic for other EM drive schemes that do not follow the shawyer, cannae, Yang, EW general form; like that guy with the weird v shaped antenna in Colorado or was it Iowa?

« Last Edit: 07/06/2015 08:31 PM by Stormbringer »
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Online Rodal

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I think it is my fault. He started his own thread. I told him it belonged in this thread because his claims fits the generalized EM drive definition. Then his thread disappeared and he was posting in here. Now it appears the thread isn't for generalized EM drives but specifically A narrow subset and mostly for independent confirmation or nullification thereof. So it is my mistake. Solution... maybe he could post  his topic independently again. Maybe a topic for other EM drive schemes that do not follow the shawyer, cannae, Yang, EW general form; like that guy with the weird v shaped antenna in Colorado or was it Iowa?
It appears that you know much more about this than I do.  Please let us know

1) at what frequency does his device works. 
2) how do you define "a generalized EM drive" as opposed to " the shawyer, cannae, Yang, EW general form".  How do they differ, specifically (other than shape).


Thank you.
« Last Edit: 07/06/2015 08:36 PM by Rodal »

Offline Stormbringer

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I think it is my fault. He started his own thread. I told him it belonged in this thread because his claims fits the generalized EM drive definition. Then his thread disappeared and he was posting in here. Now it appears the thread isn't for generalized EM drives but specifically A narrow subset and mostly for independent confirmation or nullification thereof. So it is my mistake. Solution... maybe he could post  his topic independently again. Maybe a topic for other EM drive schemes that do not follow the shawyer, cannae, Yang, EW general form; like that guy with the weird v shaped antenna in Colorado or was it Iowa?
It appears that you know much more about this than I do.  Please let us know at what frequency does his device works.  Thank you.
I don't know anything about it. :) I also don't think it (his claim) is valid for the reasons pointed out by others and yourself. Without data the claim cannot be evaluated other than negatively.

Like you and others said; without data it's just noise.

But at the same time EM drives or claims thereof are numerous and varied in schematics. There should be a place/topic thread for discussion and more importantly critical examination somewhere. There are several I am interested in as *potentially* having something more than mistake, delusion or hoax to them. That antenna one for instance has some experimental measurements and data to it even though the rationale is higher on the fringe factor than the EM drives in this thread.

EDIT:  EM drives as a general class are propellantless, involve EM energy in some form or fashion and work by a mechanism that is not immediately recognizable as working by familiar physical rules. They appear to violate one or more of the laws of physics but the violation may be illusory. There is considerable variability in the form that an EM drive can take even as there are countless forms of vehicles that have wheels and are used for personal or cargo transportation.

ETA: "there is more than one way to skin a cat." As insane, needlessly gross and cruel as the saying may be.

The most broad definition of the class would however allow ion drives, solar sails, plasma engines and so forth to be counted even though they do have fuel or working fluids and have obvious action reaction mechanisms. 
« Last Edit: 07/06/2015 09:21 PM by Stormbringer »
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