-
#2120 by meberbs on 22 Jan, 2016 13:42
-
I don't have as much experience as Dr. Rodal, but I do have some FEA experience, and agree with his statements that Yang's results do not resemble anything you would expect from numeric error.
Also as long as we are talking about Yang's mistakes, I would like to point out that I added up the results forces in the graphs here. I found that they were inconsistent. Based on what I calculated, it may have been swapping a sin and cos. Since that was such a basic mistake, and the paper didn't provide the angle of the frustum, I gave up on looking at the theory for other mistakes (not that I didn't think there would be more). Rodal's point about them ignoring the change in EM momentum per time is a good point as well, it can be hard to notice a mistake like that if you are not very familiar with the theory. -
#2121 by Tellmeagain on 22 Jan, 2016 14:03
-
Guys, I don't know how helpful this is, but I asked my Chinese (civil) engineer cousin if she could translate the JPG. Here's what she gave me:
In the Microwave Radiation Thruster, as demonstrated in the Figure 1, the direction of the electric field at the wall surface is normal to the wall surface, the direction of the of the magnetic field is perpendicular to the normal of the wall surface. Taking into account of the Formula (2), in the best resonant state, the input microwave energy in to the resonant device would be amplified Q times, as well as the values of the E ^ 2, H ^ 2, both of them would be amplified Q times, respectively, and thus the net axial thrust is:
Formula (13)
Where A1, A2, A3 are large end face area, small end face area, and the side wall surface area, respectively.
Thank you. Forgive me for that in the following I hijack your post to show what two big numbers I talked about concerning Yang's net thrust from simulation. The two big numbers are forces calculated on forward and backward directions. Are they big? Yes, compared to the net thrust which were a subtraction of the two. They can be estimated from field amplitudes from the simulations.
-
#2122 by Tellmeagain on 22 Jan, 2016 14:14
-
I don't have as much experience as Dr. Rodal, but I do have some FEA experience, and agree with his statements that Yang's results do not resemble anything you would expect from numeric error.
Also as long as we are talking about Yang's mistakes, I would like to point out that I added up the results forces in the graphs here. I found that they were inconsistent. Based on what I calculated, it may have been swapping a sin and cos. Since that was such a basic mistake, and the paper didn't provide the angle of the frustum, I gave up on looking at the theory for other mistakes (not that I didn't think there would be more). Rodal's point about them ignoring the change in EM momentum per time is a good point as well, it can be hard to notice a mistake like that if you are not very familiar with the theory.
When I talked about "numeric error" I mean accumulated numeric error due to insufficient number of elements in the finite element simulation. This numeric error is a function of number and positioning of those finite elements. If you fix the number and positioning of those finite elements, this numeric error scales with the power you feed into the simulation because Maxwell equations are linear. It is not random concerning power; it is random concerning number and positioning of the finite elements (and even so, its mean may not be zero in a range of such number and positioning).
It is not the same thing as your random numeric errors introduced by insufficient significant digits in a computer. You can't judge it with your experience from there. -
#2123 by Rodal on 22 Jan, 2016 14:19
-
Guys, I don't know how helpful this is, but I asked my Chinese (civil) engineer cousin if she could translate the JPG. Here's what she gave me:
In the Microwave Radiation Thruster, as demonstrated in the Figure 1, the direction of the electric field at the wall surface is normal to the wall surface, the direction of the of the magnetic field is perpendicular to the normal of the wall surface. Taking into account of the Formula (2), in the best resonant state, the input microwave energy in to the resonant device would be amplified Q times, as well as the values of the E ^ 2, H ^ 2, both of them would be amplified Q times, respectively, and thus the net axial thrust is:
Formula (13)
Where A1, A2, A3 are large end face area, small end face area, and the side wall surface area, respectively.
Thank you. Forgive me for that in the following I hijack your post to show what two big numbers I talked about concerning Yang's net thrust from simulation. The two big numbers are forces calculated on forward and backward directions. Are they big? Yes, compared to the net thrust which were a subtraction of the two. They can be estimated from field amplitudes from the simulations.
1) You fail to acknowledge that the forces in the above expressions do not contain absolute values, hence the sign of the forces depend on the mode shape, for transverse magnetic modes, for example the Coulomb tension can exceed the radiation pressure in some places (and hence the force changes sign at those places, from a compressive stress to a tensile stress).
2) You still fail to support your charge that Prof. Yang's calculated force is a numerical error
3) From your discussion it appears that you (TellMeAgain) have not numerically analyzed this problem to verify your statement, have you conducted a Finite Element or Finite Difference or Boundary Element method calculation for the EM Drive forces you are discussing? The appearance I get from your discussion is that you had a "hunch" that perhaps Prof. Yang's net force was not zero (your incorrect expectation (*)) because of loss of significance. Then you proceeded to state that she made a mistake because of numerical error, stating this as a fact, rather than saying that this was just your humble opinion without conducting a numerical analysis to check its veracity, or even having access to the floating point precision used by Prof. Yang in her calculations.
4) By now, I would have expected that you would have recognized that you went too far in stating that Yang incurred the mistake you are stating she made, and that you should have instead just proposed this as a possibility. Instead you continue to double down on your unsupported assertion, as if you would have had access to Prof. Yang's floating point calculations.
(*) There are other terms in the conservation of momentum equation that act as "forces" besides the Maxwell stress tensor components that are used by Prof. Yang to define her calculated force.
-
#2124 by Tellmeagain on 22 Jan, 2016 14:44
-
1) You fail to acknowledge that the forces in the above expressions do not contain absolute values, hence the sign of the forces depend on the mode shape, for transverse magnetic modes, for example the Coulomb tension can exceed the radiation pressure in some places (and hence the force changes sign at those places, from a compressive stress to a tensile stress).
2) You still fail to support your charge that Prof. Yang's calculated force is a numerical error
3) From your discussion it appears that you (TellMeAgain) have not numerically analyzed this problem, have you conducted a Finite Element or Finite Difference or Boundary Element method calculation for the EM Drive forces you are discussing? The appearance I get from your discussion is that you had a "hunch" that perhaps Prof. Yang's net force was not zero (your incorrect expectation (*)) because of loss of significance. Then you proceeded to state that she made a mistake because of numerical error, stating this as a fact, rather than saying that this was just your humble opinion without conducting a numerical analysis to check your opinion.
(*) There are other terms in the conservation of momentum equation that act as "forces" besides the Maxwell stress tensor components
Answers:
1. It was based on Yang's paper. absolute or not, "big" is in size.
2. I did not supply a strict proof. Some basically loose evidences are here, a) They used the same arrangement of finite elements in their simulations for different power levels thus the numeric error introduced by finite elements scales with power. b) They subtracted two similar big numbers (positive or negative, does not matter) to yield net thrust. c)Maxwell equations satisfy conserve of momentum, thus any net force based on Maxwell equations is zero.
My judgement of "their net thrust is a numeric error introduce by subtracting two big numbers" is base on these a,b,c.
3. No I did not do any modeling for the EmDrive, because I do not believe there exists EmDrive net thrust, and won't put too much effect into it. Also I said because of numeric errors, I did not said because loss of significance (which you said). -
#2125 by Rodal on 22 Jan, 2016 14:52
-
So, when you similarly state that NASA's Eagleworks and other experiments are due to Lorentz forces, should I assume that you make those statements based on your subjective belief, based on your experience, and that you have never actually calculated the Lorentz forces involved for the experiments that you state can be solely explained on the basis of Lorentz forces?1) You fail to acknowledge that the forces in the above expressions do not contain absolute values, hence the sign of the forces depend on the mode shape, for transverse magnetic modes, for example the Coulomb tension can exceed the radiation pressure in some places (and hence the force changes sign at those places, from a compressive stress to a tensile stress).
2) You still fail to support your charge that Prof. Yang's calculated force is a numerical error
3) From your discussion it appears that you (TellMeAgain) have not numerically analyzed this problem, have you conducted a Finite Element or Finite Difference or Boundary Element method calculation for the EM Drive forces you are discussing? The appearance I get from your discussion is that you had a "hunch" that perhaps Prof. Yang's net force was not zero (your incorrect expectation (*)) because of loss of significance. Then you proceeded to state that she made a mistake because of numerical error, stating this as a fact, rather than saying that this was just your humble opinion without conducting a numerical analysis to check your opinion.
(*) There are other terms in the conservation of momentum equation that act as "forces" besides the Maxwell stress tensor components
Answers:
1. It was based on Yang's paper. absolute or not, "big" is in size.
2. I did not supply a strict proof. Some basically loose evidences are here, a) They used the same arrangement of finite elements in their simulations for different power levels thus the numeric error introduced by finite elements scales with power. b) They subtracted two similar big numbers (positive or negative, does not matter) to yield net thrust. c)Maxwell equations satisfy conserve of momentum, thus any net force based on Maxwell equations is zero.
My judgement of "their net thrust is a numeric error introduce by subtracting two big numbers" is base on these a,b,c.
3. No I did not do any modeling for the EmDrive, because I do not believe there exists EmDrive net thrust, and won't put too much effect into it. Also I said because of numeric errors, I did not said because loss of significance (which you said).
-
#2126 by Tellmeagain on 22 Jan, 2016 14:53
-
....
4) By now, I would have expected that you would have recognized that you went too far in stating that Yang incurred the mistake you are stating she made, and that you should have instead just proposed this as a possibility. Instead you continue to double down on your unsupported assertion, as if you would have had access to Prof. Yang's floating point calculations.
Dr. Rodal,
I stated in my last post where my judgement came from. I believe that my judgement is correct, and the three evidences are solid. The sense of how strong the supports are depends on readers. For those who understand that Maxwell equations satisfy conservation of momentum, my judgement is solid. For others, maybe not.
Again, I am not talking about Prof. Yang's floating point calculation. I talked about numeric errors introduced by finite number of finite elements and that scales with power. They are not random given the number and positioning of the finite elements in their simulations.
-
#2127 by Tellmeagain on 22 Jan, 2016 15:01
-
So, when you similarly state that NASA's Eagleworks and other experiments are due to Lorentz forces, should I assume that you make those statements based on your subjective belief, based on your experience, and that you have never actually calculated the Lorentz forces involved for the experiments that you state can be solely explained on the basis of Lorentz forces?1) You fail to acknowledge that the forces in the above expressions do not contain absolute values, hence the sign of the forces depend on the mode shape, for transverse magnetic modes, for example the Coulomb tension can exceed the radiation pressure in some places (and hence the force changes sign at those places, from a compressive stress to a tensile stress).
2) You still fail to support your charge that Prof. Yang's calculated force is a numerical error
3) From your discussion it appears that you (TellMeAgain) have not numerically analyzed this problem, have you conducted a Finite Element or Finite Difference or Boundary Element method calculation for the EM Drive forces you are discussing? The appearance I get from your discussion is that you had a "hunch" that perhaps Prof. Yang's net force was not zero (your incorrect expectation (*)) because of loss of significance. Then you proceeded to state that she made a mistake because of numerical error, stating this as a fact, rather than saying that this was just your humble opinion without conducting a numerical analysis to check your opinion.
(*) There are other terms in the conservation of momentum equation that act as "forces" besides the Maxwell stress tensor components
Answers:
1. It was based on Yang's paper. absolute or not, "big" is in size.
2. I did not supply a strict proof. Some basically loose evidences are here, a) They used the same arrangement of finite elements in their simulations for different power levels thus the numeric error introduced by finite elements scales with power. b) They subtracted two similar big numbers (positive or negative, does not matter) to yield net thrust. c)Maxwell equations satisfy conserve of momentum, thus any net force based on Maxwell equations is zero.
My judgement of "their net thrust is a numeric error introduce by subtracting two big numbers" is base on these a,b,c.
3. No I did not do any modeling for the EmDrive, because I do not believe there exists EmDrive net thrust, and won't put too much effect into it. Also I said because of numeric errors, I did not said because loss of significance (which you said).
Dr. Rodal,
If you read our paper again, you will see we are much more careful in published paper than in a forum post. what stated there is not "are due to Lorentz forces" but "the phenomenon observable in this experiment provides an alternative explanation to the thrusts they detected"(in abstract) and "Our experiment suggests that the influences of the Lorentz forces can not be removed simply by subtracting the thrust measured during the null test from that measured during the resonance cavity test" (in conclusion).
Again, we have never said "solely explained on the basis of Lorentz forces", but you said that. -
#2128 by Rodal on 22 Jan, 2016 16:21
-
Addressing your surprise about my positive response to RFPlumber's testing:..
And doing some due diligence / curiosity -driven follow-up search on Mr. A. Kushelev quickly turns out that he is basically a rip-off artist, potentially with some mental issues, albeit a rather unusual one as he is luring his unsavvy "investors" in with ongoing (for at least the last 15 years) promises of new energy sources based on some colorful combinations of gem stones, ancient jewelry, millimeter wave guides, and Q factor values at resonance... It is not clear whether he is making it all up on the fly or he actually believes in his claims.
Hence there is a good chance the link to that presumably 1992 EmDrive test video is actually fake. I will be removing it.
Another important take away is there indeed happen to be some uniquely delusional people out there (who at the same time know very well what the Q factor is and how to use a VNA).
Well it is also importnat to mention that you also did not reached necessary levels of the Q in your build. I am no engineer, but from the comments I gathered, and to my suprise very positive response from Dr. Rodal on your test results - even when there are so many flaws in your build - when compared to the other builders.
1) RFPlumber's excellent use of COMSOL Finite Element Analysis to predict the resonant frequency, mode shape, electric field distribution, magnetic field distribution, current distribution in the copper metal, and heat surface losses for the investigated EM Drive. Just on this basis, unique among DoItYourself experiments. RFPlumber's understanding of the importance of thermal effects in these experiments.
2) RFPlumber's scientific approach at testing a hypothesis (https://en.wikipedia.org/wiki/Scientific_method): the strange prescription by Shawyer that the cut-off frequency condition we learned in school applies only to open waveguides should also apply for a closed resonant cavity like the EM Drive. Instead of taking this prescription for granted as many other testers have done, RFPlumber is unique among all testers (not just DIY testers, since Shawyer has never published any experimental data supporting his strange cut-off prescription) in actually testing an EM Drive slightly below cut-off and slightly above cut-off, and hence nullifying that Shawyer hypothesis (for force predictions over 200 microNewtons according to RFPlumber) and validating the well-known fact that cut-off frequency for open waveguides does not apply to closed-resonant cavities like the EM Drive.
3) Just this contribution alone by RFPlumber's is extremely important as NASA's test without a dielectric showed absolutely no thrust (both for the Cannae drive and for the Shawyer frustum of a cone). It has been shown without a shadow of a doubt that NASA's test without a dielectric was in resonance (see https://forum.nasaspaceflight.com/index.php?topic=39214.msg1469685#msg1469685 and subsequent posts in that thread). The last bastion of defense by Shawyer's defenders has been that the NASA test showing no anomalous force without a dielectric was slightly below cut-off frequency for an open waveguide. Although this defense has very dubious validity (the EM Drive ends are not open: they are closed by copper plates), RFPlumber's test has served to further weaken that defense and further props up NASA's result of no anomalous force without a dielectric.
And just think about it: for those that think that NASA's anomalous force is due to a Lorentz force contribution, why should NASA measure no anomalous force whatsoever without a dielectric insert, while always measuring a force when a dielectric insert was used? What difference does the disks of HDPE dielectric insert make to the Lorentz force?
Do I think that RFPlumber deserves to be congratulated on this basis alone (aside from the generous, selfless amount of personal time and money RFPlumber dedicated to this effort) ? You bet ya
-
#2129 by glennfish on 22 Jan, 2016 16:41
-
Do I think that RFPlumber deserves to be congratulated on this basis alone (aside from the generous, selfless amount of personal time and money RFPlumber dedicated to this effort) ? You bet ya
Just to throw my two cents in.
While I personally don't like the approach he took to his statistical analysis, there's nothing fundamentally wrong with his approach given that he was looking for signals above pre-defined thresholds under conditions he clearly defined and constrained. In that context, his findings are appropriate and valid. The difference between his approach and mine is I would have looked for any signal which would require significantly more data reduction, which I may still do. However, my approach is outside the scope of what he was trying to do.
He clearly constrained what he was looking for and how he was looking for it, and granted that, his data and his statistics support his interpretation.
Consider this a mealy mouthed way of agreeing that he deserves kudos for a job well done. -
#2130 by SeeShells on 22 Jan, 2016 16:49
-
I'll admit he did a service in stepping up to the build with COMSOL and time and money and we all gained from his null testing. Very nice presentation of null force and there is no bad data and I gained from his presentation and even validated some of the reasons for doing what I'm doing in my build.
Addressing your surprise about my positive response to RFPlumber's testing:..
And doing some due diligence / curiosity -driven follow-up search on Mr. A. Kushelev quickly turns out that he is basically a rip-off artist, potentially with some mental issues, albeit a rather unusual one as he is luring his unsavvy "investors" in with ongoing (for at least the last 15 years) promises of new energy sources based on some colorful combinations of gem stones, ancient jewelry, millimeter wave guides, and Q factor values at resonance... It is not clear whether he is making it all up on the fly or he actually believes in his claims.
Hence there is a good chance the link to that presumably 1992 EmDrive test video is actually fake. I will be removing it.
Another important take away is there indeed happen to be some uniquely delusional people out there (who at the same time know very well what the Q factor is and how to use a VNA).
Well it is also importnat to mention that you also did not reached necessary levels of the Q in your build. I am no engineer, but from the comments I gathered, and to my suprise very positive response from Dr. Rodal on your test results - even when there are so many flaws in your build - when compared to the other builders.
1) RFPlumber's excellent use of COMSOL Finite Element Analysis to predict the resonant frequency, mode shape, electric field distribution, magnetic field distribution, current distribution in the copper metal, and heat surface losses for the investigated EM Drive. Just on this basis, unique among DoItYourself experiments.
2) RFPlumber's scientific approach at examining a hypothesis. The strange prescription by Shawyer that the cut-off frequency condition we learned in school applies only to open waveguides should also apply for a closed resonant cavity like the EM Drive. Instead of taking this prescription for granted as many other testers have done, RFPlumber is unique among all testers (not just DIY testers, since Shawyer has never published any experimental data supporting his strange cut-off prescription) in actually testing an EM Drive slightly below cut-off and slightly above cut-off, and hence nullifying that Shawyer hypothesis (for force predictions over 200 microNewtons according to RFPlumber) and validating the well-known fact that cut-off frequency for open waveguides does not apply to closed-resonant cavities like the EM Drive.
3) Just this contribution alone by RFPlumber's is extremely important as NASA's test without a dielectric showed absolutely no thrust (both for the Cannae drive and for the Shawyer frustum of a cone). It has been shown without a shadow of a doubt that NASA's test without a dielectric was in resonance (see https://forum.nasaspaceflight.com/index.php?topic=39214.msg1469685#msg1469685 and subsequent posts in that thread). The last bastion of defense by Shawyer's defenders has been that the NASA test showing no anomalous force without a dielectric was slightly below cut-off frequency for an open waveguide. Although this defense has very dubious validity, RFPlumber's test has served to further weaken that defense and further props up NASA's result of no anomalous force without a dielectric.
And just think about it: for those that think that NASA's anomalous force is due to a Lorentz force contribution, why should NASA measure no anomalous force whatsoever without a dielectric insert, while always measuring a force when a dielectric insert was used? What difference does the small disks of dielectric insert make to the Lorentz force?
Do I think that RFPlumber need to be congratulated on this basis alone (aside from the amount of personal time and money he dedicated to this effort) ? You bet yaQuoteAnd just think about it: for those that think that NASA's anomalous force is due to a Lorentz force contribution, why should NASA measure no anomalous force whatsoever without a dielectric insert, while always measuring a force when a dielectric insert was used? What difference does the small disks of dielectric insert make to the Lorentz force?
Lorentz forces are present when there is a current flow. It's the force on a charge in electromagnetic field. F = qv x B, q is the charge, v is the velocity, and B is the magnetic field density and it's perpendicular to both velocity and magnetic field.
From this you can deduce two things, more current was flowing in one case vs the other or the wires were laid out differently, which we don't know if that's the case. I would say we need more information on the tests with dielectric inserts vs no dielectric inserts to know what happened and how.
Back to my build.
Shell -
#2131 by Rodal on 22 Jan, 2016 16:59
-
...
NASA measured absolutely NO force (within their force measurement sensitivity) when no dielectric inserts were present for both the Cannae and the Shawyer-type frustum of a cone. So there was a difference of about ~2 orders of magnitude (taking into account measurement sensitivity) in the NASA measured anomalous force with and without dielectric. Can it be shown that the calculated Lorentz forces should be ~2 orders of magnitude smaller without a dielectric insert ?QuoteAnd just think about it: for those that think that NASA's anomalous force is due to a Lorentz force contribution, why should NASA measure no anomalous force whatsoever without a dielectric insert, while always measuring a force when a dielectric insert was used? What difference does the small disks of dielectric insert make to the Lorentz force?
Lorentz forces are present when there is a current flow. It's the force on a charge in electromagnetic field. F = qv x B, q is the charge, v is the velocity, and B is the magnetic field density and it's perpendicular to both velocity and magnetic field.
Form this you can deduce two things, more current was flowing in one case vs the other or the wires were laid out differently, which we don't know if that's the case. I would say we need more information on the tests with dielectric inserts vs no dielectric inserts to know what happened and how.
Back to my build.
Shell
Particularly when:
Anomalous Thrust Production from an RF Test Device Measured on a Low-Thrust Torsion Pendulum
David A. Brady*, Harold G. White†, Paul March‡, James T. Lawrence§, and Frank J. Davies**
NASA Lyndon B. Johnson Space Center, Houston, Texas 77058
50th AIAA/ASME/SAE/ASEE Joint Propulsion Conference
http://www.libertariannews.org/wp-content/uploads/2014/07/AnomalousThrustProductionFromanRFTestDevice-BradyEtAl.pdf
TE012 NASA tests
Power Measured force
measurement without dielectric inserts 30 watts 0 microNewtons
measurement with dielectric inserts 2.6 watts 55 microNewtons
The power used for the measurement without dielectric inserts was more than 10 times greater than the amount of power for the measurement with dielectric, so that the data shows the opposite: all things being equal the data shows that the Lorentz force should have been greater (>10 times greater power) with the test without a dielectric insert, which is the complete opposite of what the data shows
So it appears based on this data (assuming everything else being the same) that Lorentz forces may not have been responsible for NASA's measured force of 55 microNewtons with a dielectric insert -
#2132 by SeeShells on 22 Jan, 2016 17:38
-
...
NASA measured absolutely NO force (within their force measurement sensitivity) when no dielectric inserts were present for both the Cannae and the Shawyer-type frustum of a cone. So there was a difference of about ~2 orders of magnitude (taking into account measurement sensitivity) in the NASA measured anomalous force with and without dielectric. Can it be shown that the calculated Lorentz forces should be ~2 orders of magnitude smaller without a dielectric insert ?QuoteAnd just think about it: for those that think that NASA's anomalous force is due to a Lorentz force contribution, why should NASA measure no anomalous force whatsoever without a dielectric insert, while always measuring a force when a dielectric insert was used? What difference does the small disks of dielectric insert make to the Lorentz force?
Lorentz forces are present when there is a current flow. It's the force on a charge in electromagnetic field. F = qv x B, q is the charge, v is the velocity, and B is the magnetic field density and it's perpendicular to both velocity and magnetic field.
Form this you can deduce two things, more current was flowing in one case vs the other or the wires were laid out differently, which we don't know if that's the case. I would say we need more information on the tests with dielectric inserts vs no dielectric inserts to know what happened and how.
Back to my build.
Shell
Particularly when:
Anomalous Thrust Production from an RF Test Device Measured on a Low-Thrust Torsion Pendulum
David A. Brady*, Harold G. White†, Paul March‡, James T. Lawrence§, and Frank J. Davies**
NASA Lyndon B. Johnson Space Center, Houston, Texas 77058
50th AIAA/ASME/SAE/ASEE Joint Propulsion Conference
http://www.libertariannews.org/wp-content/uploads/2014/07/AnomalousThrustProductionFromanRFTestDevice-BradyEtAl.pdf
TE012 NASA tests
Power Measured force
measurement without dielectric inserts 30 watts 0 microNewtons
measurement with dielectric inserts 2.6 watts 55 microNewtons
The power used for the measurement without dielectric inserts was more than 10 times greater than the amount of power for the measurement with dielectric, so that the data shows the opposite: all things being equal the data shows that the Lorentz force should have been greater (>10 times greater power) with the test without a dielectric insert, which is the complete opposite of what the data shows
So it appears based on this data (assuming everything else being the same) that Lorentz forces may not have been responsible for NASA's measured force of 55 microNewtons with a dielectric insert
Yes, assuming everything else remained the same.
Is this the one where they melted the plastic screws holding in the dielectric plate? Surely not with 2.6 Watts?
I'll need to read the paper again.
Shell -
#2133 by Tellmeagain on 22 Jan, 2016 17:45
-
...
NASA measured absolutely NO force (within their force measurement sensitivity) when no dielectric inserts were present for both the Cannae and the Shawyer-type frustum of a cone. So there was a difference of about ~2 orders of magnitude (taking into account measurement sensitivity) in the NASA measured anomalous force with and without dielectric. Can it be shown that the calculated Lorentz forces should be ~2 orders of magnitude smaller without a dielectric insert ?QuoteAnd just think about it: for those that think that NASA's anomalous force is due to a Lorentz force contribution, why should NASA measure no anomalous force whatsoever without a dielectric insert, while always measuring a force when a dielectric insert was used? What difference does the small disks of dielectric insert make to the Lorentz force?
Lorentz forces are present when there is a current flow. It's the force on a charge in electromagnetic field. F = qv x B, q is the charge, v is the velocity, and B is the magnetic field density and it's perpendicular to both velocity and magnetic field.
Form this you can deduce two things, more current was flowing in one case vs the other or the wires were laid out differently, which we don't know if that's the case. I would say we need more information on the tests with dielectric inserts vs no dielectric inserts to know what happened and how.
Back to my build.
Shell
Particularly when:
Anomalous Thrust Production from an RF Test Device Measured on a Low-Thrust Torsion Pendulum
David A. Brady*, Harold G. White†, Paul March‡, James T. Lawrence§, and Frank J. Davies**
NASA Lyndon B. Johnson Space Center, Houston, Texas 77058
50th AIAA/ASME/SAE/ASEE Joint Propulsion Conference
http://www.libertariannews.org/wp-content/uploads/2014/07/AnomalousThrustProductionFromanRFTestDevice-BradyEtAl.pdf
TE012 NASA tests
Power Measured force
measurement without dielectric inserts 30 watts 0 microNewtons
measurement with dielectric inserts 2.6 watts 55 microNewtons
The power used for the measurement without dielectric inserts was more than 10 times greater than the amount of power for the measurement with dielectric, so that the data shows the opposite: all things being equal the data shows that the Lorentz force should have been greater (>10 times greater power) with the test without a dielectric insert, which is the complete opposite of what the data shows
So it appears based on this data (assuming everything else being the same) that Lorentz forces may not have been responsible for NASA's measured force of 55 microNewtons with a dielectric insert
Dr. Rodal,
This can happen if when EW measured the frustum without insert, they accidentally did not ground (well) the frustum; while when they measured the frustum with insert, they accidentally well grounded the frustum. Since we can not be sure that everything else (other than the insert) being the same, we can not rule out Lorentz forces for causing NASA's measured force of 55 microNewtons with insert.
-
#2134 by Rodal on 22 Jan, 2016 18:00
-
Yes, assuming everything else remained the same.
Is this the one where they melted the plastic screws holding in the dielectric plate? Surely not with 2.6 Watts?
I'll need to read the paper again.
Shell
No, not at all.
The "melting" of the plastic screws occurred when using dielectric inserts, including a PTFE disk at the large end, and it is not reported in the NASA AIAA paper, instead the "melting" of the plastic screws was reported by Paul March in the NSF threads, and it was clearly present only in the tests with dielectric inserts (*)Quotehttp://Notsosureofit:
We've fried a number of nylon bolts and have found that the best way to keep them from getting cooked is to keep them out of the high E-field regions in the cavity. For Instance we tested the copper frustum in its TM010 mode and mounted a 5.0 inch OD by 1.0" thick PTFE disk at the center of the large OD end cap of the copper frustum with one 1/4-20 nylon bolt. We got some large thrust signatures in that configuration, see attached slide, but the dam nylon bolt kept melting and dropping the PTFE discs into the main body of the cavity. Brother did that look like a magnitude 9 earthquake on our uN resolution force measurement system!
That said, I'm wondering if the nylon bolts themselves could be contributing to the measured force we are seeing? It has a much smaller volume than the PE and PTFE discs, but they have a much higher dissipation factor than PE or PTFE that could translate into more work done converting E&M momentum into mechanical forces.
Best, Paul M.
https://forum.nasaspaceflight.com/index.php?topic=36313.msg1335583#msg1335583QuoteDr. Rodal & Notsosureofit:
We had an interesting failure in the Eagleworks lab yesterday. That being I was getting ready to pull a vacuum on our copper frustum mounted in its "reverse" or to the right thrust vector position and ran a preliminary data un to see if it was performing in air as it had two weeks ago just before our last RF amplifier died. Sadly it wasn't for it was producing less than half of what it did before and in the wrong direction!
I had Dr. White come in and take a look over my latest test article installation last night and he found that the center 1/4"-20 nylon PE disc mounting bolt that holds the second PE disc to the small OD frustum's PCB endplate was no-longer tensioned as it had been before. In fact it had partially melted at the interface between the two PE discs thus relieving the strain induced by its bolts threads and nut. (There are three ~1.00" 1/4-20 nylon bolts mounted on a ~2.00" radius spaced every 120 degrees that hold the first PE disc to the PCB end cap. There is then a layer of 3/4" wide office scotch tape at the interface between the first and second PE discs and the center 1/4"-20 nylon bolt that hold second PE disc to the first PE disc.)
Apparently not having the PE discs firmly mounted to the frustum's small OD end cap hindered the thrust producing mechanism that conveys the generated forces in the PE to the copper frustum. And/or the melted nylon was hogging all the RF energy in the PE discs due to its higher dissipation factor in its semiliquid state. Either way it looks like there is a high E-field volume where this center nylon bolt hangs out while running in the TM212 resonant mode. Too bad Teflon bolts are so weak even in comparison to the nylon, for its dissipation factor is at least two orders of magnitude lower than the nylon's.
Best, Paul M.
https://forum.nasaspaceflight.com/index.php?topic=36313.msg1335190#msg1335190
You get more dissipated heat with a dielectric polymer (Nylon, HDPE, PTFE) because of the tan delta of the dielectric insert.
_________
(*) I write "melting" with quotation marks because it appears like thermoplastic ("Nylon") polymer softening due to higher temperature. Based on the report it appears that the temperature did not go over the melting temperature of the thermoplastic, just went over the softening point of the polymer. -
#2135 by X_RaY on 22 Jan, 2016 18:04
-
What is with the 50Ω dummy-Load test? EW used shielded RG-142 coaxial cable for the RF power. The amplifier consumes a lot of DC power i.e. relative strong currents... BUT this is also the case for the dummy-Load test! Using the Load there was NO thrust at all....
NASA measured absolutely NO force (within their force measurement sensitivity) when no dielectric inserts were present for both the Cannae and the Shawyer-type frustum of a cone. So there was a difference of about ~2 orders of magnitude (taking into account measurement sensitivity) in the NASA measured anomalous force with and without dielectric. Can it be shown that the calculated Lorentz forces should be ~2 orders of magnitude smaller without a dielectric insert ?QuoteAnd just think about it: for those that think that NASA's anomalous force is due to a Lorentz force contribution, why should NASA measure no anomalous force whatsoever without a dielectric insert, while always measuring a force when a dielectric insert was used? What difference does the small disks of dielectric insert make to the Lorentz force?
Lorentz forces are present when there is a current flow. It's the force on a charge in electromagnetic field. F = qv x B, q is the charge, v is the velocity, and B is the magnetic field density and it's perpendicular to both velocity and magnetic field.
Form this you can deduce two things, more current was flowing in one case vs the other or the wires were laid out differently, which we don't know if that's the case. I would say we need more information on the tests with dielectric inserts vs no dielectric inserts to know what happened and how.
Back to my build.
Shell
Particularly when:
Anomalous Thrust Production from an RF Test Device Measured on a Low-Thrust Torsion Pendulum
David A. Brady*, Harold G. White†, Paul March‡, James T. Lawrence§, and Frank J. Davies**
NASA Lyndon B. Johnson Space Center, Houston, Texas 77058
50th AIAA/ASME/SAE/ASEE Joint Propulsion Conference
http://www.libertariannews.org/wp-content/uploads/2014/07/AnomalousThrustProductionFromanRFTestDevice-BradyEtAl.pdf
TE012 NASA tests
Power Measured force
measurement without dielectric inserts 30 watts 0 microNewtons
measurement with dielectric inserts 2.6 watts 55 microNewtons
The power used for the measurement without dielectric inserts was more than 10 times greater than the amount of power for the measurement with dielectric, so that the data shows the opposite: all things being equal the data shows that the Lorentz force should have been greater (>10 times greater power) with the test without a dielectric insert, which is the complete opposite of what the data shows
So it appears based on this data (assuming everything else being the same) that Lorentz forces may not have been responsible for NASA's measured force of 55 microNewtons with a dielectric insert
Dr. Rodal,
This can happen if when EW measured the frustum without insert, they accidentally did not ground (well) the frustum; while when they measured the frustum with insert, they accidentally well grounded the frustum. Since we can not be sure that everything else (other than the insert) being the same, we can not rule out Lorentz forces for causing NASA's measured force of 55 microNewtons with insert.
-
#2136 by Rodal on 22 Jan, 2016 18:20
-
...
Sure, we can pile up unverified supposition upon unverified supposition. That's why I was careful to state "assuming everything else stays the same".
Dr. Rodal,
This can happen if when EW measured the frustum without insert, they accidentally did not ground (well) the frustum; while when they measured the frustum with insert, they accidentally well grounded the frustum. Since we can not be sure that everything else (other than the insert) being the same, we can not rule out Lorentz forces for causing NASA's measured force of 55 microNewtons with insert.
But that is a long, long way from establishing that Lorentz forces were responsible for NASA's measured forces. -
#2137 by CW on 22 Jan, 2016 18:36
-
#2138 by Tellmeagain on 22 Jan, 2016 18:39
-
What is with the 50Ω dummy-Load test? EW used shielded RG-142 coaxial cable for the RF power. The amplifier consumes a lot of DC power i.e. relative strong currents... BUT this is also the case for the dummy-Load test! Using the Load there was NO thrust at all.
This can be explained by everything was subtracted with the dummy-load test. The dummy-Load test is subtracted with the dummy-Load test to yield zero. I emphasize that this is just speculation, to provide a possibility. I did not say this was what actually happened. -
#2139 by RFPlumber on 22 Jan, 2016 18:40
-
...
TE012 NASA tests
Power Measured force
measurement without dielectric inserts 30 watts 0 microNewtons
measurement with dielectric inserts 2.6 watts 55 microNewtons
The power used for the measurement without dielectric inserts was more than 10 times greater than the amount of power for the measurement with dielectric, so that the data shows the opposite: all things being equal the data shows that the Lorentz force should have been greater (>10 times greater power) with the test without a dielectric insert, which is the complete opposite of what the data shows
So it appears based on this data (assuming everything else being the same) that Lorentz forces may not have been responsible for NASA's measured force of 55 microNewtons with a dielectric insert
Dr. Rodal, can you, please, elaborate on why do you think that 55 uN number above matters at all given that all those corresponding forces in the 50-200 uN range disappeared in vacuum? (And when not in vacuum, the force trace was showing a rather typical thermal profile with long post-RF tail).
EDIT: And there is no indication that those 50-200 uN forces when present where ever observed to change direction...
