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#940 by VIY on 25 Sep, 2016 00:28
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...
On the ship A = F/M rules. The energy / work required to be done on the constant mass of the ship to effect velocity change never varies. The ship doesn't care what some other frame calculates as the necessary energy to cause velocity change.
Sorry to interrupt, but the above is a wrong interpretation of the Newtons law. There F is an external force acting on M. In a closed system there is no acceleration. Its mass center awlays moves with constant velocity. Basic physics.
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#941 by meberbs on 25 Sep, 2016 00:32
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This rebuttal of the CoE over unity arguments seems pertinent: http://ssi.org/epi/Over-Unity_Argument_&_Mach_Effect_Thrusters.pdf
That is what I responded to a few posts back. The short version is that the paper is completely wrong. -
#942 by rfmwguy on 25 Sep, 2016 00:50
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I would suggest the existing nsf thread
http://forum.nasaspaceflight.com/index.php?topic=31037.0
Is the proper locale for Mach effect discussions so the emdrive threads remain on topic. 😼 -
#943 by Rodal on 25 Sep, 2016 01:06
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Discussion of conservation of momentum and conservation of energy, as well as possible acceleration of the EM Drive , as explained by the Mach effect of course best belongs in the EM Drive Developments - related to space flight applications thread, instead of other threads. It is plainly obvious that one does not need to start a thread on "conservation of momentum" to discuss conservation of momentum of the EM Drive. Ditto for "conservation of energy" of the EM Drive. Ditto one does not need to start a thread on "Lorentz forces" to discuss Lorentzian forces on the EM Drive and for countless other discussions of the EM Drive
And it is also obvious that if there would be an existing thread titled "Propellant-less Electromagnetic Propulsion", it would be best to discuss electromagnetic issues of the EM Drive in this thread than in another possibly existing one that may be addressing other types of electric propulsion (like electromagnetic tethers).
The emphasis of this thread has been very well stated already by D_Dom, in the first page of this thread, and we might as well repeat it to clear up any confusion:Quote from: D_DomThis is a thread - Thread 8 in the series - focused on objective analysis of whether the EM Drive (a 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.
The thread
http://forum.nasaspaceflight.com/index.php?topic=31037.0
is devoted to the Woodward type experiments with piezoelectric/electrostrictive (usually PZT) stacks at much lower frequencies (~35 KHz) than what is being discussed here: an electromagnetic resonance in a cavity at ~2 GHz (orders of magnitude higher frequency).
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#944 by zen-in on 25 Sep, 2016 01:17
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.... When you do that CoE is violated and of course momentum is not conserved. This is true for any reactionless drive. I don't consider planetary assist to be reactionless propulsion because the planet is pulling the spacecraft and momentum is tranferred using gravity.
At the Estes Park Breakthrough Propulsion Workshop, Dr. Jean-Philippe Montillet of the École Polytechnique Fédérale de Lausanne, Switzerland, presented a paper titled "Model of the EM Drive with the EMG coupling" (that mathematically and physically) explains the EM Drive as a capacitor, where:
* Surface currents propagate inside the cavity on the conic wall (between the two end plates)
* electromagnetic resonant modes create electric charges on each end plate
* Mach/Woodward effect is triggered by Lorentz force from surface currents on the conic wall
* acceleration of RF cavity as due to the variation of Electro Magnetic density from evanescent waves inside the skin layer
A polymer insert placed asymmetrically in the cavity results in greater asymmetry, while decreasing Q. The cavity's acceleration is a function of all the above factors. The model can explain acceleration with and without the polymer insert (to a more significant or less significant extent).
As the Mach/Woodward effect can be derived straight from the fully covariant nonlinear Hoyle Narlikar gravitational theory or it can also be obtained from linearized General Relativity it is really as much of a gravitational effect as gravity assist. The difference being that gravity assist is something that people are now familiar with (since it was first used for interplanetary flight by the Mariner 10 in the mid-70's) and the Mach/Woodward effect is something that people are normally unfamiliar with (because time-dependent terms in General Relativity are usually ignored).
Gravity assist flight of a spacecraft is an open system where momentum is transferred by gravity to spaceship and so is the Mach/Woodward effect a gravitational effect. Both of them are explained by General Relativity. If somebody explains the acceleration of an EM Drive based on a gravitational effect (the Mach/Woodward effect), it would be incorrect to address conservation of momentum and energy solely based on the spaceship momentum while ignoring the effect of gravity.
Of course, nobody nowadays will write about "overunity" of gravity assist (as the spaceship involved in a sling shot maneuver apparently gains velocity out of nothing, if one ignores gravity) because it is evident that gravity assist is ... gravity-assisted.
Similarly, the Mach/Woodward effect drive perhaps should be renamed "Mach Effect Gravity Assist" (MEGA) drive, to make it more obvious to the readers that the Mach Effect is a gravitational effect, and thus it would be completely incorrect to address conservation of momentum and energy without taking into account the gravitational effect.
I will look for that talk when the video becomes available. However my first reaction to this idea that a cavity can act like a capaciter is to ask whoever makes that claim to look at the boundary conditions. The inside of the cavity is a conductor so any em field at that interface will have a high current, low voltage node. There are RF topologies that do act like capacitors. They are usually at the end of a 1/4λ driven conductor, typically an antenna, and sometimes have rounded flat surfaces. At resonance the cavity would be purely resistive. The inductive reactance and capacitive reactance are conjugates. For maximum power to be coupled to the EM-Drive (ie: highest Q) the inductive reactance and capacitive reactance have to be complex conjugates. So to say an EM-Drive is a kind of capacitor does not make physical sense. That's just my opinion. I am interested to see how this idea is developed and how it causes the thrust claimed for EM-Drives. -
#945 by WarpTech on 25 Sep, 2016 01:32
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I will look for that talk when the video becomes available. However my first reaction to this idea that a cavity can act like a capaciter is to ask whoever makes that claim to look at the boundary conditions. The inside of the cavity is a conductor so any em field at that interface will have a high current, low voltage node. There are RF topologies that do act like capacitors. They are usually at the end of a 1/4λ driven conductor, typically an antenna, and sometimes have rounded flat surfaces. At resonance the cavity would be purely resistive. The inductive reactance and capacitive reactance are conjugates. For maximum power to be coupled to the EM-Drive (ie: highest Q) the inductive reactance and capacitive reactance have to be complex conjugates. So to say an EM-Drive is a kind of capacitor does not make physical sense. That's just my opinion. I am interested to see how this idea is developed and how it causes the thrust claimed for EM-Drives.
If you read my last paper, then you should understand that Gravity can be modeled as damping of the resonance, aka "resistance". As Q increases, so do the losses from resistance due to higher power and current, and the thrust increases accordingly. I suspect that the reason we haven't heard about the great performance of a superconducting frustum, is because when all the resistive losses are removed, so is the thrust. Shawyer is probably still trying to figure out why it doesn't work with 1000X more thrust than the non-superconducting drive.
https://www.researchgate.net/publication/305501551_AN_ENGINEERING_MODEL_OF_QUANTUM_GRAVITY -
#946 by Rodal on 25 Sep, 2016 01:34
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...
We have to wait for permission from the author to post the presentation (or more preferable for the mathematical paper). The boundary conditions are of course taken into account.
I will look for that talk when the video becomes available. However my first reaction to this idea that a cavity can act like a capaciter is to ask whoever makes that claim to look at the boundary conditions. The inside of the cavity is a conductor so any em field at that interface will have a high current, low voltage node. There are RF topologies that do act like capacitors. They are usually at the end of a 1/4λ driven conductor, typically an antenna, and sometimes have rounded flat surfaces. At resonance the cavity would be purely resistive. The inductive reactance and capacitive reactance are conjugates. For maximum power to be coupled to the EM-Drive (ie: highest Q) the inductive reactance and capacitive reactance have to be complex conjugates. So to say an EM-Drive is a kind of capacitor does not make physical sense. That's just my opinion. I am interested to see how this idea is developed and how it causes the thrust claimed for EM-Drives.
A piezoelectric crystal in a piezoelectric transducer away from resonance can most roughly be modeled also as a capacitor. Why? Because impedance (away from resonance) goes down with frequency. Of course to take into account resonance, you have to add an inductor and a resistor, as a minimal model, and so does Montillet, in his paper.
For example, the classical model for a piezoelectric crystal is that of a main capacitor connected in parallel to 1) a resistor, 2) another capacitor, and 3) an inductance. See the Van Dycke model and many circuit models by Mason.
Now, more to the point, here are circuit models used by LINAC School for RF resonant cavities:
And here is the model by Thomas Jefferson Lab
And here is the type of model shown by Montillet in his presentation:
The equivalent circuit of the Single Frequency Cavity Resonator (SFCR)
Of course - we all know - that actual cavities have an infinite number of eigenvalues and eigenmodes, but for conceptual understanding is well accepted that in proximity of a given known eigenmode one can conceptualize the behavior as such a simple circuit to understand what is going on.
And by the way, Montillet only discusses equivalent circuit models to facilitate understanding of the differential equations involved.
Of course, since Montillet's discussion involves evanescent waves, Montillet treatment in his paper is mathematical and not based on equivalent circuits
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#947 by tchernik on 25 Sep, 2016 01:47
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If you read my last paper, then you should understand that Gravity can be modeled as damping of the resonance, aka "resistance". As Q increases, so do the losses from resistance due to higher power and current, and the thrust increases accordingly. I suspect that the reason we haven't heard about the great performance of a superconducting frustum, is because when all the resistive losses are removed, so is the thrust. Shawyer is probably still trying to figure out why it doesn't work with 1000X more thrust than the non-superconducting drive.
Is that the start of technical insight from theoretical understanding that we are seeing here?
Seems like indeed a lot happened in that workshop, that we have yet to see surface.
Also, if I understand well what you are saying, a superconductive Emdrive is simply a wrong path. Only non superconductive ones would show any effect.
Which makes me wonder, how strong can it get? which are the critical parameters to optimize for seeing a clear signal from any experiment, according to this model? -
#948 by Rodal on 25 Sep, 2016 01:51
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If you read my last paper, then you should understand that Gravity can be modeled as damping of the resonance, aka "resistance". As Q increases, so do the losses from resistance due to higher power and current, and the thrust increases accordingly. I suspect that the reason we haven't heard about the great performance of a superconducting frustum, is because when all the resistive losses are removed, so is the thrust. Shawyer is probably still trying to figure out why it doesn't work with 1000X more thrust than the non-superconducting drive.
Is that the start of technical insight from theoretical understanding that we are seeing here?
Seems like indeed a lot happened in that workshop, that we have yet to see surface.
Also, if I understand well what you are saying, a superconductive Emdrive is simply a wrong path. Only non superconductive ones would show any effect.
Which makes me wonder, how strong can it get? which are the critical parameters to optimize for seeing a clear signal from any experiment, according to this model?
By the way, Todd's presentation was excellent and very well received
There was strong interest in it, and was resonant with other points of view. -
#949 by WarpTech on 25 Sep, 2016 01:55
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If you read my last paper, then you should understand that Gravity can be modeled as damping of the resonance, aka "resistance". As Q increases, so do the losses from resistance due to higher power and current, and the thrust increases accordingly. I suspect that the reason we haven't heard about the great performance of a superconducting frustum, is because when all the resistive losses are removed, so is the thrust. Shawyer is probably still trying to figure out why it doesn't work with 1000X more thrust than the non-superconducting drive.
Is that the start of technical insight from theoretical understanding that we are seeing here?
Seems like indeed a lot happened in that workshop, that we have yet to see surface.
Also, if I understand well what you are saying, a superconductive Emdrive is simply a wrong path. Only non superconductive ones would show any effect.
Which makes me wonder, how strong can it get? which are the critical parameters to optimize for seeing a clear signal from any experiment, according to this model?
If I could answer those questions I'd be famous. There seems to be a common theme pertaining to gravity, and damping as presented in my paper. My "prediction" is that the superconducting frustum won't work. DIY'ers might consider using other materials besides copper, such as brass or nickel, or asymmetrical metal end plates such as copper in the back and nickel in the front, and see how these compare to copper. I don't have any other insights at this time. -
#950 by Rodal on 25 Sep, 2016 02:07
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If you read my last paper, then you should understand that Gravity can be modeled as damping of the resonance, aka "resistance". As Q increases, so do the losses from resistance due to higher power and current, and the thrust increases accordingly. I suspect that the reason we haven't heard about the great performance of a superconducting frustum, is because when all the resistive losses are removed, so is the thrust. Shawyer is probably still trying to figure out why it doesn't work with 1000X more thrust than the non-superconducting drive.
Is that the start of technical insight from theoretical understanding that we are seeing here?
Seems like indeed a lot happened in that workshop, that we have yet to see surface.
Also, if I understand well what you are saying, a superconductive Emdrive is simply a wrong path. Only non superconductive ones would show any effect.
Which makes me wonder, how strong can it get? which are the critical parameters to optimize for seeing a clear signal from any experiment, according to this model?
If I could answer those questions I'd be famous. There seems to be a common theme pertaining to gravity, and damping as presented in my paper. My "prediction" is that the superconducting frustum won't work. DIY'ers might consider using other materials besides copper, such as brass or nickel, or asymmetrical metal end plates such as copper in the back and nickel in the front, and see how these compare to copper. I don't have any other insights at this time.
I would put this in a more uncertain terms.
In a superconducting cavity, the skin depth is not zero. In case of superconductor: skin depth δ must be replaced with London penetration depth (https://en.wikipedia.org/wiki/London_penetration_depth
https://en.wikipedia.org/wiki/London_equations). Also: https://en.wikipedia.org/wiki/Meissner_effect
Since the reason for superconductivity in a material is quite complex, naive extrapolations to the effectiveness of a superconducting EM Drive cannot and should not be based on just extrapolating results obtained from copper cavities based on "Q" quality factor scaling. (As some experimenters may have initially hoped)
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#951 by WarpTech on 25 Sep, 2016 02:37
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If you read my last paper, then you should understand that Gravity can be modeled as damping of the resonance, aka "resistance". As Q increases, so do the losses from resistance due to higher power and current, and the thrust increases accordingly. I suspect that the reason we haven't heard about the great performance of a superconducting frustum, is because when all the resistive losses are removed, so is the thrust. Shawyer is probably still trying to figure out why it doesn't work with 1000X more thrust than the non-superconducting drive.
Is that the start of technical insight from theoretical understanding that we are seeing here?
Seems like indeed a lot happened in that workshop, that we have yet to see surface.
Also, if I understand well what you are saying, a superconductive Emdrive is simply a wrong path. Only non superconductive ones would show any effect.
Which makes me wonder, how strong can it get? which are the critical parameters to optimize for seeing a clear signal from any experiment, according to this model?
If I could answer those questions I'd be famous. There seems to be a common theme pertaining to gravity, and damping as presented in my paper. My "prediction" is that the superconducting frustum won't work. DIY'ers might consider using other materials besides copper, such as brass or nickel, or asymmetrical metal end plates such as copper in the back and nickel in the front, and see how these compare to copper. I don't have any other insights at this time.
I would put this in a more uncertain terms.
In a superconducting cavity, the skin depth is not zero. In case of superconductor: skin depth δ must be replaced with London penetration depth (https://en.wikipedia.org/wiki/London_penetration_depth
https://en.wikipedia.org/wiki/London_equations). Also: https://en.wikipedia.org/wiki/Meissner_effect
Since the reason for superconductivity in a material is quite complex, naive extrapolations to the effectiveness of a superconducting EM Drive cannot and should not be based on just extrapolating results obtained from copper cavities based on "Q" quality factor scaling. (As some experimenters may have initially hoped)
It would be interesting if the big end were superconducting and the rest was not.
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#952 by SeeShells on 25 Sep, 2016 03:45
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Todd, sometimes you hurt my brain with your insight.If you read my last paper, then you should understand that Gravity can be modeled as damping of the resonance, aka "resistance". As Q increases, so do the losses from resistance due to higher power and current, and the thrust increases accordingly. I suspect that the reason we haven't heard about the great performance of a superconducting frustum, is because when all the resistive losses are removed, so is the thrust. Shawyer is probably still trying to figure out why it doesn't work with 1000X more thrust than the non-superconducting drive.
Is that the start of technical insight from theoretical understanding that we are seeing here?
Seems like indeed a lot happened in that workshop, that we have yet to see surface.
Also, if I understand well what you are saying, a superconductive Emdrive is simply a wrong path. Only non superconductive ones would show any effect.
Which makes me wonder, how strong can it get? which are the critical parameters to optimize for seeing a clear signal from any experiment, according to this model?
If I could answer those questions I'd be famous. There seems to be a common theme pertaining to gravity, and damping as presented in my paper. My "prediction" is that the superconducting frustum won't work. DIY'ers might consider using other materials besides copper, such as brass or nickel, or asymmetrical metal end plates such as copper in the back and nickel in the front, and see how these compare to copper. I don't have any other insights at this time.
I would put this in a more uncertain terms.
In a superconducting cavity, the skin depth is not zero. In case of superconductor: skin depth δ must be replaced with London penetration depth (https://en.wikipedia.org/wiki/London_penetration_depth
https://en.wikipedia.org/wiki/London_equations). Also: https://en.wikipedia.org/wiki/Meissner_effect
Since the reason for superconductivity in a material is quite complex, naive extrapolations to the effectiveness of a superconducting EM Drive cannot and should not be based on just extrapolating results obtained from copper cavities based on "Q" quality factor scaling. (As some experimenters may have initially hoped)
It would be interesting if the big end were superconducting and the rest was not.
I've taken the weekend off to sit in a bubbling hot springs tub (birthday present) and unwind.QuoteDr. Jean-Philippe Montillet of the École Polytechnique Fédérale de Lausanne, Switzerland, presented a paper titled "Model of the EM Drive with the EMG coupling"
. I'll be looking forward to reading the paper when I get back home to a proper computer. It was nearly impossible to hear him speak on skype.
I'm glad someone took my ramblings seriously on the evanescent wave functions and the blending of the Mach effect and other theories.
You all have a good weekend.
My Best,
Shell -
#953 by Rodal on 25 Sep, 2016 03:55
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...I'm glad someone took my ramblings seriously on the evanescent wave functions and the blending of the Mach effect and other theories.
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#954 by Gilbertdrive on 25 Sep, 2016 10:58
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.... When you do that CoE is violated and of course momentum is not conserved. This is true for any reactionless drive. I don't consider planetary assist to be reactionless propulsion because the planet is pulling the spacecraft and momentum is tranferred using gravity.
At the Estes Park Breakthrough Propulsion Workshop, Dr. Jean-Philippe Montillet of the École Polytechnique Fédérale de Lausanne, Switzerland, presented a paper titled "Model of the EM Drive with the EMG coupling" (that mathematically and physically) explains the EM Drive as a capacitor, where:
* Surface currents propagate inside the cavity on the conic wall (between the two end plates)
* electromagnetic resonant modes create electric charges on each end plate
* Mach/Woodward effect is triggered by Lorentz force from surface currents on the conic wall
* acceleration of RF cavity as due to the variation of Electro Magnetic density from evanescent waves inside the skin layer
A polymer insert placed asymmetrically in the cavity results in greater asymmetry, while decreasing Q. The cavity's acceleration is a function of all the above factors. The model can explain acceleration with and without the polymer insert (to a more significant or less significant extent).
As the Mach/Woodward effect can be derived straight from the fully covariant nonlinear Hoyle Narlikar gravitational theory or it can also be obtained from linearized General Relativity it is really as much of a gravitational effect as gravity assist. The difference being that gravity assist is something that people are now familiar with (since it was first used for interplanetary flight by the Mariner 10 in the mid-70's) and the Mach/Woodward effect is something that people are normally unfamiliar with (because time-dependent terms in General Relativity are usually ignored).
Gravity assist flight of a spacecraft is an open system where momentum is transferred by gravity to spaceship and so is the Mach/Woodward effect a gravitational effect. Both of them are explained by General Relativity. If somebody explains the acceleration of an EM Drive based on a gravitational effect (the Mach/Woodward effect), it would be incorrect to address conservation of momentum and energy solely based on the spaceship momentum while ignoring the effect of gravity.
Of course, nobody nowadays will write about "overunity" of gravity assist (as the spaceship involved in a sling shot maneuver apparently gains velocity out of nothing, if one ignores gravity) because it is evident that gravity assist is ... gravity-assisted.
Similarly, the Mach/Woodward effect drive perhaps should be renamed "Mach Effect Gravity Assist" (MEGA) drive, to make it more obvious to the readers that the Mach Effect is a gravitational effect, and thus it would be completely incorrect to address conservation of momentum and energy without taking into account the gravitational effect.
Very interesting.
It think it is important to notice again clearly that the recent developpements about constant thrust for constant imput power and overunity were not for the aim of telling that the Em-effect was impossible; nor to reject experimental results. It was about several things.
1 : All reported experiments are at zero speed relatively to the earth, or at low speeds comparated to what is needed for space travel. So there is no experimental evidence about the comportement at high speeds relatively to earth.
2 : The Overunity argument was mentionned in the context of theories where the emdrive was not stealing Energy to anything. Shaywer and the Traveller do not pretend that the emdrive is stealing energy to something else.
When I (and some others) gave the argument or overunity, we had some answers like :
The Traveller : It does not matter since in the accelerating referential of the ship the Kinetic Energy is always zero, so no problem.
Or some others : There are Kinetic Energy conudrum even with classical rockets, when more Kinetic Energy is gained that chemical energy was spent, so we gain energy, but it does not violate CoE.
That was about this type of answers that my messages were.
Some assumed "an Emship get more Kinetic energy than it spent of electricity, because it is stealing energy to something else"
It is perfect for me. I already listed several possible cases, I just modified my own citation to make it more explicit.
Totally agree for relative velocity and kinetic energy. I agree also It is not a proof that the Emdrive don't work. There are at least 4 possibilities (probably there are many others)
1 : Emdrive doesn't work. No new physic needed.
2 : Emdrive works, and does not violate CoE, because it exists non classical reference frames to define appropriately Kinetic Energy, and the Emdrive has a way of pushing against this reference frame. It does not give a constant acceleration, but an acceleration decreasing proportionnaly to the speed in the reference frame it is pushing against. New physics needed.
3 : Emdrive works, gives constant acceleration at constant power, but CoE is still not violated, because it is a way of stealing Energy to something else. Mutable Quantum Vacuum for example, or via gravity. New physics needed.
4 : Emdrive works at constant acceleration at constant power, without stealing energy to anything else. It violates CoE. New physics needed.
Also, again, at the attention of The Diyers, especially RFMWguy and SeeShells
All the argumentation that was given recently by me, Meberbs, Tellmeagain, Wicoe, was about the way the emdrive could comport in space, and how, if it is working like announced by Shawyer in his peer-rewieved publication, getting 0,67C in 10 years, it would violates CoE. It was not about your experiments, since your experiments are at low or zero speed in an earth referential. It does not means that the Emdrive did not work. It was not about that. It was about theory.
I still find interesting to differenciate theories about the Emdrive that violates CoE from the theory that does not violate CoE.
To come back to your message, Dr Rodal, if the frustrum is explained as a capacitor, does it mean that the thrust could be a Biefeld-Brown effect ? It would be very sad. -
#955 by rfmwguy on 25 Sep, 2016 11:17
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Discussion of conservation of momentum and conservation of energy, as well as possible acceleration of the EM Drive , as explained by the Mach effect of course best belongs in the EM Drive Developments - related to space flight applications thread, instead of other threads. It is plainly obvious that one does not need to start a thread on "conservation of momentum" to discuss conservation of momentum of the EM Drive. Ditto for "conservation of energy" of the EM Drive. Ditto one does not need to start a thread on "Lorentz forces" to discuss Lorentzian forces on the EM Drive and for countless other discussions of the EM Drive
Delineating competitive theories and hardware is critical for the readership imho especially for science media whom are following emdrive closely. "Closed" RF frustum cavities are the emdrive. Cannae is not and neither is Woodward's Mach effect nor nassikas. Trying to blur the lines seems disingenuous as these 8 threads have been emdrive from day 1.
And it is also obvious that if there would be an existing thread titled "Propellant-less Electromagnetic Propulsion", it would be best to discuss electromagnetic issues of the EM Drive in this thread than in another possibly existing one that may be addressing other types of electric propulsion (like electromagnetic tethers).
The emphasis of this thread has been very well stated already by D_Dom, in the first page of this thread, and we might as well repeat it to clear up any confusion:Quote from: D_DomThis is a thread - Thread 8 in the series - focused on objective analysis of whether the EM Drive (a 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.
The thread
http://forum.nasaspaceflight.com/index.php?topic=31037.0
is devoted to the Woodward type experiments with piezoelectric/electrostrictive (usually PZT) stacks at much lower frequencies (~35 KHz) than what is being discussed here: an electromagnetic resonance in a cavity at ~2 GHz (orders of magnitude higher frequency).
Coe/com can apply anywhere and is a well discussed subtopic here. My vote has always been towards staying on topic rather than attempting to broaden an otherwise large topic. Emdrive is already a massive thread series, no need to boost it with Mach effect, nassikasn or cannae.
Like you, I'm just a part time poster here with my own point of view. Nsf staff can decide if renaming or broadening emdrive is the best thing to do. 😀 -
#956 by Star One on 25 Sep, 2016 11:20
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.... When you do that CoE is violated and of course momentum is not conserved. This is true for any reactionless drive. I don't consider planetary assist to be reactionless propulsion because the planet is pulling the spacecraft and momentum is tranferred using gravity.
At the Estes Park Breakthrough Propulsion Workshop, Dr. Jean-Philippe Montillet of the École Polytechnique Fédérale de Lausanne, Switzerland, presented a paper titled "Model of the EM Drive with the EMG coupling" (that mathematically and physically) explains the EM Drive as a capacitor, where:
* Surface currents propagate inside the cavity on the conic wall (between the two end plates)
* electromagnetic resonant modes create electric charges on each end plate
* Mach/Woodward effect is triggered by Lorentz force from surface currents on the conic wall
* acceleration of RF cavity as due to the variation of Electro Magnetic density from evanescent waves inside the skin layer
A polymer insert placed asymmetrically in the cavity results in greater asymmetry, while decreasing Q. The cavity's acceleration is a function of all the above factors. The model can explain acceleration with and without the polymer insert (to a more significant or less significant extent).
As the Mach/Woodward effect can be derived straight from the fully covariant nonlinear Hoyle Narlikar gravitational theory or it can also be obtained from linearized General Relativity it is really as much of a gravitational effect as gravity assist. The difference being that gravity assist is something that people are now familiar with (since it was first used for interplanetary flight by the Mariner 10 in the mid-70's) and the Mach/Woodward effect is something that people are normally unfamiliar with (because time-dependent terms in General Relativity are usually ignored).
Gravity assist flight of a spacecraft is an open system where momentum is transferred by gravity to spaceship and so is the Mach/Woodward effect a gravitational effect. Both of them are explained by General Relativity. If somebody explains the acceleration of an EM Drive based on a gravitational effect (the Mach/Woodward effect), it would be incorrect to address conservation of momentum and energy solely based on the spaceship momentum while ignoring the effect of gravity.
Of course, nobody nowadays will write about "overunity" of gravity assist (as the spaceship involved in a sling shot maneuver apparently gains velocity out of nothing, if one ignores gravity) because it is evident that gravity assist is ... gravity-assisted.
Similarly, the Mach/Woodward effect drive perhaps should be renamed "Mach Effect Gravity Assist" (MEGA) drive, to make it more obvious to the readers that the Mach Effect is a gravitational effect, and thus it would be completely incorrect to address conservation of momentum and energy without taking into account the gravitational effect.
Very interesting.
It think it is important to notice again clearly that the recent developpements about constant thrust for constant imput power and overunity were not for the aim of telling that the Em-effect was impossible; nor to reject experimental results. It was about several things.
1 : All reported experiments are at zero speed relatively to the earth, or at low speeds comparated to what is needed for space travel. So there is no experimental evidence about the comportement at high speeds relatively to earth.
2 : The Overunity argument was mentionned in the context of theories where the emdrive was not stealing Energy to anything. Shaywer and the Traveller do not pretend that the emdrive is stealing energy to something else.
When I (and some others) gave the argument or overunity, we had some answers like :
The Traveller : It does not matter since in the accelerating referential of the ship the Kinetic Energy is always zero, so no problem.
Or some others : There are Kinetic Energy conudrum even with classical rockets, when more Kinetic Energy is gained that chemical energy was spent, so we gain energy, but it does not violate CoE.
That was about this type of answers that my messages were.
Some assumed "an Emship get more Kinetic energy than it spent of electricity, because it is stealing energy to something else"
It is perfect for me. I already listed several possible cases, I just modified my own citation to make it more explicit.
Totally agree for relative velocity and kinetic energy. I agree also It is not a proof that the Emdrive don't work. There are at least 4 possibilities (probably there are many others)
1 : Emdrive doesn't work. No new physic needed.
2 : Emdrive works, and does not violate CoE, because it exists non classical reference frames to define appropriately Kinetic Energy, and the Emdrive has a way of pushing against this reference frame. It does not give a constant acceleration, but an acceleration decreasing proportionnaly to the speed in the reference frame it is pushing against. New physics needed.
3 : Emdrive works, gives constant acceleration at constant power, but CoE is still not violated, because it is a way of stealing Energy to something else. Mutable Quantum Vacuum for example, or via gravity. New physics needed.
4 : Emdrive works at constant acceleration at constant power, without stealing energy to anything else. It violates CoE. New physics needed.
Also, again, at the attention of The Diyers, especially RFMWguy and SeeShells
All the argumentation that was given recently by me, Meberbs, Tellmeagain, Wicoe, was about the way the emdrive could comport in space, and how, if it is working like announced by Shawyer in his peer-rewieved publication, getting 0,67C in 10 years, it would violates CoE. It was not about your experiments, since your experiments are at low or zero speed in an earth referential. It does not means that the Emdrive did not work. It was not about that. It was about theory.
I still find interesting to differenciate theories about the Emdrive that violates CoE from the theory that does not violate CoE.
To come back to your message, Dr Rodal, if the frustrum is explained as a capacitor, does it mean that the thrust could be a Biefeld-Brown effect ? It would be very sad.
Why sad? -
#957 by flux_capacitor on 25 Sep, 2016 11:22
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Quote
Dr. Jean-Philippe Montillet of the École Polytechnique Fédérale de Lausanne, Switzerland, presented a paper titled "Model of the EM Drive with the EMG coupling"
. I'll be looking forward to reading the paper when I get back home to a proper computer. It was nearly impossible to hear him speak on skype.
I'm glad someone took my ramblings seriously on the evanescent wave functions and the blending of the Mach effect and other theories.
You all have a good weekend.
My Best,
Shell
And I'm glad Dr. Montillet kept working on a theroretical explanation of EmDrive thrust, we heard from him back to thread 6! -
#958 by Gilbertdrive on 25 Sep, 2016 11:30
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To come back to your message, Dr Rodal, if the frustrum is explained as a capacitor, does it mean that the thrust could be a Biefeld-Brown effect ? It would be very sad.
Why sad?
https://en.wikipedia.org/wiki/Biefeld%E2%80%93Brown_effect
Because the Biefeld-Brown effect is admitted to rely on corona discharges, and does not work in vacuum. -
#959 by Star One on 25 Sep, 2016 11:34
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To come back to your message, Dr Rodal, if the frustrum is explained as a capacitor, does it mean that the thrust could be a Biefeld-Brown effect ? It would be very sad.
Why sad?
https://en.wikipedia.org/wiki/Biefeld%E2%80%93Brown_effect
Because the Biefeld-Brown effect is admitted to rely on corona discharges, and does not work in vacuum.
Thank you. And according to that link you end up with these.
https://en.m.wikipedia.org/wiki/Ionocraft
