Author Topic: EM Drive Developments - related to space flight applications - Thread 2  (Read 2514380 times)

dustinthewind

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Re: EM Drive Developments - related to space flight applications - Thread 2
« Reply #1520 on: 03/25/2015 09:07 PM »
I believe this article has more to do with two currents out of phase by 90 degrees than the first article I posted.  I'll be sure to review it again to make sure.  http://arxiv.org/pdf/1502.06288v1.pdf .
« Last Edit: 03/26/2015 12:56 AM by dustinthewind »

frobnicat

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Re: EM Drive Developments - related to space flight applications - Thread 2
« Reply #1521 on: 03/25/2015 11:11 PM »
The idea is correct, often used to demonstrate the twin paradox in General Relativity not Special Relativity.  (My pet peeve)  Special is only for Inertial frames.  Forces and acceleration require General Relativity, so they wind up using the limit of an approximation instead.

Edit: I have to read this paper in more detail, but first glance, it looks like you might get an impulse during this rather select interval but I don't (yet) see any consideration of the recovery of initial conditions w/o reversing it.

I second you on the (also at first glance) apparent problem of having any kind of stationary net average force in a direction with this approach. From the article (at least what is on arxiv) : the meat is equation (66)  F=cst*I1bar*I2bar/tau˛ (number of turns assumed constant).

I don't know the academic history and prestige of the journal in which this is published, but unless the published version is significantly edited, this is a case of notation abuse and almost deceit in conclusion drawing from correct equations, (I assume they are correct, would took me some weeks to understand and check in details). The bar notation usually denotes a time averaged value of a time varying stationary value, be it periodic, or quasiperiodic, or random, but it must be that  ( integral(0 to T) V(t)dt )/T converges to some value when T->+infinity for Vbar to have a meaning. Unless there are other usages I'm unaware of ? Please educate me if so.

Anyway (bottom page 12) : A constant force may be achieved by having a direct current in one loop I1(t) =I1bar and a current of uniform second derivative on the other I2(t)=1/2 I2bar*t˛/tau˛
Green sensible use of bar notation
Red deceiving use of bar notation : I2(t) defined as having a uniform second derivative (wrt time) can't be stationary. I2bar is ill defined. For instance if a given I2(t) is defined by I2bar=1 and tau=1, the exact same I2(t) could also be defined by by I2bar=100 and tau=10. There are 2 "free parameters" introduced when in fact saying "uniform second derivative" requires only one : I2(t) = 1/2 CurAcc*t˛  where CurAcc (Current Acceleration) is the only needed parameter and has units of A/s˛. This might be ugly, maybe a "representative" current value in A (I2bar) + "representative" time value in s (tau) is more "expressive" and elegant. As absolute values, it's not clear what they are representative of though, since 1A 1s is equivalent to 100A 10s

But abuse of notation and introducing more parameters than necessary is not the problem by itself, and the equation (66) is still as valid written with I2bar/tau˛ term  as it would be with CurAcc term. Equations all right. But then we forget that I2bar notation was just a commodity, that there is no real stationary I2(t) behind that, and that the force given by the expression can only be a transient, since 1/2 CurAcc*t˛ will soon exceed any reasonable current carrying capacity (superconducting or not). And assuming a clever possibility, like cutting the current abruptly (in the loop) to put it back to 0 periodically, is doomed to fail as much as any attempt to transform repetitive mechanical effects inside a capsule into net acceleration (Dean drive...). What was gained during an acceleration phase will be lost by a deceleration phase, if the driving parameter (Intensity, Position...) is to be made periodic.

This derives clearly from eq. (51) (from which eq. (66) itself derives) :
F(t) proportional to I1(t)*I2dotdot(t) - I1dotdot(t)*I2(t)
Is it conceivable to have 2 stationary I1(t) and I2(t) (in the sense defined above that I1bar and I2bar have a real meaning) that yield Fbar different from 0 ? I don't see a clever elegant mathematical proof to that but I'm rather sure it is impossible. If someone disagree please state a clear explicit counter example I1(t) I2(t) (for any t) with Fbar different from 0 and I1 and I2 stationary, that is ( integral(0 to T) I(t)dt )/T converges to some value (0 or whatever) when T->+infinity.

The example I1 constant and I2 "uniformly accelerated" given by the paper don't meet the requirement : I2 not stationary. This is a one shot effect. It's not really different from shooting a bullet at constant m/s˛ in a mass driver fixed to the hull of a spacecraft. As long as the bullet is accelerating in the mass driver, the mass driver gives a constant "thrust" to the spacecraft. But then what ? Either the bullet is free to leave the spacecraft : conventional reaction propulsion, spacecraft loses propellent mass. Or else it is "recycled", which implies some deceleration of it to 0 (wrt spacecraft), which will cancel exactly the gained momentum, be it hard or soft is irrelevant (damages or sparks aside).

BTW we also understand that playing with "delayed" forces in relativity it's not surprising to get non null instant forces on a system. If "a system" is an ensemble of elements separated by some distance, then there is not really such thing as an instant force on the system as a whole since there is no such thing as an instant for the system. SR is enough to show that the notion of intrinsic instant is ill defined wrt the system's parts : "instant sum of local forces seen by each part" depend on arbitrary inertial rest frame.

What is going on with hard science those days ? Do brilliant people make a living of writing correct complicated equations to hint at spectacular but delusional conclusions from them ?

RonM

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Re: EM Drive Developments - related to space flight applications - Thread 2
« Reply #1522 on: 03/26/2015 12:11 AM »
FYI

http://www.technologyreview.com/view/536091/spacecraft-traveling-close-to-light-speed-should-be-visible-with-current-technology-say/?utm_source=feedburner&utm_medium=email&utm_campaign=Feed%3A+arxivblog%2FGmoU+%28The+Physics+arXiv+Blog%29

Quote
The movement of a relativistic spacecraft will have another effect. It should scatter the cosmic microwave background in a way that produces a unique signature. “As a baryonic spacecraft travels at relativistic speeds it will interact with the CMB through scattering to cause a frequency shift that could be detectable on Earth with current technology,” say Yurtsever and Wilkinson.

Please excuse the somewhat off topic question, but would this also apply to the interaction of an Alcubierre drive or similar manipulation of space-time with the CMB?

Rodal

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Re: EM Drive Developments - related to space flight applications - Thread 2
« Reply #1523 on: 03/26/2015 12:27 AM »
The idea is correct, often used to demonstrate the twin paradox in General Relativity not Special Relativity.  (My pet peeve)  Special is only for Inertial frames.  Forces and acceleration require General Relativity, so they wind up using the limit of an approximation instead.

Edit: I have to read this paper in more detail, but first glance, it looks like you might get an impulse during this rather select interval but I don't (yet) see any consideration of the recovery of initial conditions w/o reversing it.

I second you on the (also at first glance) apparent problem of having any kind of stationary net average force in a direction with this approach. From the article (at least what is on arxiv) : the meat is equation (66)  F=cst*I1bar*I2bar/tau˛ (number of turns assumed constant).

I don't know the academic history and prestige of the journal in which this is published, but unless the published version is significantly edited, this is a case of notation abuse and almost deceit in conclusion drawing from correct equations, (I assume they are correct, would took me some weeks to understand and check in details). The bar notation usually denotes a time averaged value of a time varying stationary value, be it periodic, or quasiperiodic, or random, but it must be that  ( integral(0 to T) V(t)dt )/T converges to some value when T->+infinity for Vbar to have a meaning. Unless there are other usages I'm unaware of ? Please educate me if so.

Anyway (bottom page 12) : A constant force may be achieved by having a direct current in one loop I1(t) =I1bar and a current of uniform second derivative on the other I2(t)=1/2 I2bar*t˛/tau˛
Green sensible use of bar notation
Red deceiving use of bar notation : I2(t) defined as having a uniform second derivative (wrt time) can't be stationary. I2bar is ill defined. For instance if a given I2(t) is defined by I2bar=1 and tau=1, the exact same I2(t) could also be defined by by I2bar=100 and tau=10. There are 2 "free parameters" introduced when in fact saying "uniform second derivative" requires only one : I2(t) = 1/2 CurAcc*t˛  where CurAcc (Current Acceleration) is the only needed parameter and has units of A/s˛. This might be ugly, maybe a "representative" current value in A (I2bar) + "representative" time value in s (tau) is more "expressive" and elegant. As absolute values, it's not clear what they are representative of though, since 1A 1s is equivalent to 100A 10s

But abuse of notation and introducing more parameters than necessary is not the problem by itself, and the equation (66) is still as valid written with I2bar/tau˛ term  as it would be with CurAcc term. Equations all right. But then we forget that I2bar notation was just a commodity, that there is no real stationary I2(t) behind that, and that the force given by the expression can only be a transient, since 1/2 CurAcc*t˛ will soon exceed any reasonable current carrying capacity (superconducting or not). And assuming a clever possibility, like cutting the current abruptly (in the loop) to put it back to 0 periodically, is doomed to fail as much as any attempt to transform repetitive mechanical effects inside a capsule into net acceleration (Dean drive...). What was gained during an acceleration phase will be lost by a deceleration phase, if the driving parameter (Intensity, Position...) is to be made periodic.

This derives clearly from eq. (51) (from which eq. (66) itself derives) :
F(t) proportional to I1(t)*I2dotdot(t) - I1dotdot(t)*I2(t)
Is it conceivable to have 2 stationary I1(t) and I2(t) (in the sense defined above that I1bar and I2bar have a real meaning) that yield Fbar different from 0 ? I don't see a clever elegant mathematical proof to that but I'm rather sure it is impossible. If someone disagree please state a clear explicit counter example I1(t) I2(t) (for any t) with Fbar different from 0 and I1 and I2 stationary, that is ( integral(0 to T) I(t)dt )/T converges to some value (0 or whatever) when T->+infinity.

The example I1 constant and I2 "uniformly accelerated" given by the paper don't meet the requirement : I2 not stationary. This is a one shot effect. It's not really different from shooting a bullet at constant m/s˛ in a mass driver fixed to the hull of a spacecraft. As long as the bullet is accelerating in the mass driver, the mass driver gives a constant "thrust" to the spacecraft. But then what ? Either the bullet is free to leave the spacecraft : conventional reaction propulsion, spacecraft loses propellent mass. Or else it is "recycled", which implies some deceleration of it to 0 (wrt spacecraft), which will cancel exactly the gained momentum, be it hard or soft is irrelevant (damages or sparks aside).

BTW we also understand that playing with "delayed" forces in relativity it's not surprising to get non null instant forces on a system. If "a system" is an ensemble of elements separated by some distance, then there is not really such thing as an instant force on the system as a whole since there is no such thing as an instant for the system. SR is enough to show that the notion of intrinsic instant is ill defined wrt the system's parts : "instant sum of local forces seen by each part" depend on arbitrary inertial rest frame.

What is going on with hard science those days ? Do brilliant people make a living of writing correct complicated equations to hint at spectacular but delusional conclusions from them ?
After your demolishing review, I decided to look into more detail into the Jounal, and I noticed the "Plus" at the end (instead of A or B).

concerning <<What is going on with hard science those days ? Do brilliant people make a living of writing correct complicated equations to hint at spectacular but delusional conclusions from them ?>>

Quote
What can we look forward to this year in regards to your journal’s content or development?

EPJ Plus is a newly born journal of the EPJ series, a continuation of Il Nuovo Cimento B formely published by the Italian Physical Society. It has been launched in 2011 as an electronic-only journal, with a new interdisciplinary approach in terms of topics and a wider portfolio of possible article formats. EPJ Plus is also meant as a "cascade" journal for the other EPJs. In the last two years, the number of articles published in EPJ Plus has significantly grown and its impact factor expectations are definitely promising. According to the recent editorial policy of the journal, invited contents, grouped in topical "Focus Points", will be boosted and contributions from new fields, such as accelerator physics or physics applied to cultural heritage or to energy, will be strongly encouraged.

The authors have a patent application in the US:

« Last Edit: 03/26/2015 12:36 AM by Rodal »

dustinthewind

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Re: EM Drive Developments - related to space flight applications - Thread 2
« Reply #1524 on: 03/26/2015 12:43 AM »
(Dustinthewind - here is a quote from the other thread, "A scientific paper that clarifies how newtons 3rd law does not apply to the time delay of information and how it can be used for electromagnetic propulsion.  It provides a mathematical background for the time delayed magnetic fields but first illustrating how the static equations miss the effect.  https://scholar.google.com/scholar?cluster=7136673109349846373&hl=en&as_sdt=0,48" it is titled, "Newton's Third Law in the Framework of Special Relativity" )

I'll have to apologize if I wasted anyone's time.  I realized the paper is not what I thought it was about after frobnicat's review.  I expected two current loops changing in time out of phase but per the review I went back and sure enough it is about a current loop constantly on while one changes.

Rodal

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Re: EM Drive Developments - related to space flight applications - Thread 2
« Reply #1525 on: 03/26/2015 01:36 AM »
(Dustinthewind - here is a quote from the other thread, "A scientific paper that clarifies how newtons 3rd law does not apply to the time delay of information and how it can be used for electromagnetic propulsion.  It provides a mathematical background for the time delayed magnetic fields but first illustrating how the static equations miss the effect.  https://scholar.google.com/scholar?cluster=7136673109349846373&hl=en&as_sdt=0,48" it is titled, "Newton's Third Law in the Framework of Special Relativity" )

I'll have to apologize if I wasted anyone's time.  I realized the paper is not what I thought it was about after frobnicat's review.  I expected two current loops changing in time out of phase but per the review I went back and sure enough it is about a current loop constantly on while one changes.

No need to apologize

Welcome to our forum.

We have discussed more "out there" papers than this one (which was peer-reviewed at a well-known European parent journal and whose authors claimed association with a renowned European Mathematical Institute).  A number of papers, theories and experiments that have been explored in this thread have appeared in less renowned publications and/or have not been peer-reviewed
« Last Edit: 03/26/2015 01:39 AM by Rodal »

ThinkerX

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Re: EM Drive Developments - related to space flight applications - Thread 2
« Reply #1526 on: 03/26/2015 01:57 AM »
Quote
Very interesting paper! Especially considering what Roger Shawyer says about conservation of momentum in "open systems"… To summarize his point of view, standard Newtonian mechanics and thus the law of conservation of momentum indicate that, no matter what shape the cavity is, the forces exerted upon it from within must balance to zero. Shawyer claims this statement ignores special relativity, in which separate frames of reference have to be applied when velocities approach the speed of light. He declares that in the EmDrive, the system of electromagnetic waves and the waveguide can be regarded as an open system, both having separate frames of reference. He also says this effect is similar to the principle of the laser gyroscope, which is also an apparently closed system device, but where the beams act as if having an external frame of reference (which they have, since the speed of light is constant).

However, Shawyer was severely criticized by the scientific community for this "not even wrong" idea. And frankly, I wonder if Tuval & Yahalom's initial assumption regarding the "transmission of any information limited by the speed of light" is really correct, since it is established the Abraham–Lorentz force and inertial reaction forces are instantaneous. Another counterexample involving instantaneousness is quantum entanglement.

[EDIT]I didn't saw at first that Roger Shawyer's idea is opposite (the "open system") than the "closed system" treatment in special relativity by Miron Tuval & Asher Yahalom. It's weird because both seem to claim the same idea: decoupling the EM effects between two interacting electric circuits.

Ok, my interest here is in what Shawyer has to say.  It seems fairly apparent he is ahead of the pack when it comes to building/testing these devices - each time we considered a different approach, Shawyer has been there and built a relevant prototype, like as not.  Given this, is there any way to salvage his operational theory here that doesn't involve direct violation of the laws of physics?  Is there some legitimate way his explanation could be shoehorned into the gaps between GR and SR and QM?  Keeping in mind he is an experimenter first and theorist second.

zen-in

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Re: EM Drive Developments - related to space flight applications - Thread 2
« Reply #1527 on: 03/26/2015 02:28 AM »

The authors have a patent application in the US:

What they have is some kind of motor or electromagnetic actuator.   In the description section the theory of operation is described:

"The scope of this invention rests on the well known phenomenology of electromagnetic asymmetric systems that do not abide by Newton's Third Law. It should be noted that the law of momentum conservation is maintained during operation of the system of the present invention, as the momentum gained by the material system is counter-balanced by an opposite momentum gained by the electromagnetic field. This provides that the total momentum of the entire physical system, which is composed of both matter and field, is conserved."

While it is true that momentum can be transferred via a magnetic field, the momentum is transferred to whatever physical entity maintains said magnetic field.   When two magnets repel or attract each other the magnets move to positions that minimize the potential energy of the magnetic fields.

Stormbringer

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Re: EM Drive Developments - related to space flight applications - Thread 2
« Reply #1528 on: 03/26/2015 02:42 AM »
FYI

http://www.technologyreview.com/view/536091/spacecraft-traveling-close-to-light-speed-should-be-visible-with-current-technology-say/?utm_source=feedburner&utm_medium=email&utm_campaign=Feed%3A+arxivblog%2FGmoU+%28The+Physics+arXiv+Blog%29

Quote
The movement of a relativistic spacecraft will have another effect. It should scatter the cosmic microwave background in a way that produces a unique signature. “As a baryonic spacecraft travels at relativistic speeds it will interact with the CMB through scattering to cause a frequency shift that could be detectable on Earth with current technology,” say Yurtsever and Wilkinson.

Please excuse the somewhat off topic question, but would this also apply to the interaction of an Alcubierre drive or similar manipulation of space-time with the CMB?
i think it would be somewhat similar. i always envisioned it as producing a burst of gamma rays and x rays at the start of a FTL movement and a burst when it comes out of FTL mode. but now you have to add a moving and rising emission spectra as it gets to its top speed prior to warp. and a reverse of this on the other end as it may deaccelerate at the destination.
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Star-Drive

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Re: EM Drive Developments - related to space flight applications - Thread 2
« Reply #1529 on: 03/26/2015 02:49 AM »
....
The copper frustum thrust reversal due to only its dielectric placement came when I was experimenting with the TM010 mode,...
... I think that this mode shape correct designation is TM011 instead of TM010 because:

1) There can be no TMmn0 modes for a truncated cone.  TMmn0 modes need to have a constant electromagnetic field in the longitudinal direction of the cavity.  This is possible for a cylindrical cavity (containing no other dielectrics inside besides the cavity medium) because it has constant geometrical and material properties in the longitudinal direction.  But a conical cavity has variable cross-section in the longitudinal direction, therefore the  TMnn0 mode is not possible.  The first possible mode (if it is not cut-off) is TMmn1.  The exact solution for the truncated cone shows this.  See for example:  http://gregegan.customer.netspace.net.au/SCIENCE/Cavity/Cavity.html   :The quantum mode number "p" for a truncated cone is related to k.   k cannot be zero for a truncated cone, since k = ω/c for a truncated cone , therefore k = 0 implies zero frequency for a truncated cone.

2) As the attached plot shows, COMSOL's FEA plot shows an electromagnetic field that is not constant in the longitudinal direction, therefore this is not TM010, it looks instead as TM011 upon closer inspection.

(Therefore the analyst's designation for TM011 should be changed to TM012 and so forth for TM01p modes)
I have been examining higher modes for the truncated cone cavity and mode shapes for truncated cones with larger cone angle and for smaller base diameters at the same cone angle.

For these cases (mode shapes with higher "m" azimuthal quantum number, and those with smaller base diameters compared to the big base diameter) the difference between the truncated mode shapes and the cylindrical mode shape becomes more significant.

Ultimately this was unavoidable, because the only quantum number that the truncated cone and the cylindrical cavity have in common is "m" the azimuthal quantum mode number.  The variation along the circumference is described by a harmonic function in both the truncated cone and the cylindrical cavity.

On the other hand, the variation along "n" is described by Associated Legendre P functions in terms of the cone's angle for the truncated cone while it is described in terms of zero Bessel functions of the radial polar coordinate for the cylindrical cavity.  Different functions in terms of different variables.

And the variation along "p" is described by Spherical Bessel functions in terms of the spherical radial coordinate for the truncated cone, while it is described in terms of harmonic functions of the longitudinal polar coordinate for the cylindrical cavity.  Different functions in terms of different variables.

I have not found in the literature a commonly accepted nomenclature to designate mode shapes for the truncated cone.

Furthermore, for this thread's audience, the cylindrical mode shapes are something that the audience can more immediately relate to, since the cylindrical mode shape nomenclature is found in the literature, and @Notsosureofit's formula is based on an analogy to the cylindrical cavity mode shapes (using the Bessel zero functions to characterize the mode shapes).

Therefore, to better communicate these mode shapes, and to avoid confusion I have decided to identify the truncated mode shapes in future communications as follows:

1. Always specifying the frequency at which they take place.
2. Whenever possible to provide plots to illustrate the actual mode shape.
3. Whenever possible to provide the designation for the closest cylindrical mode shape.  I will identify these as "Cyl. TMmnp"

Of course, for high mode numbers and/or large cone angles we will find mode shapes that cannot be described in terms of a cylindrical cavity analogy.  In those cases those modes are best described by their frequency and a plot showing the actual mode shape.

Therefore, I will describe what NASA Eagleworks describes as mode TM212 as "Cyl. TM212" from now on.

There is still a discrepancy regarding what NASA Eagleworks describes as mode TM010, which I think should be described "Cyl. TM011" because this mode shape for the truncated cone is not constant along the longitudinal axis of the truncated cone (as NASA Eagleworks's own plot shows).

Dr. Rodal:

I asked our first COMSOL analyst his opinion on this resonant mode naming issue and attached is Frank's comments on same.

Best, Paul M.
« Last Edit: 03/27/2015 02:34 AM by Star-Drive »
Star-Drive

Stormbringer

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Re: EM Drive Developments - related to space flight applications - Thread 2
« Reply #1530 on: 03/26/2015 03:04 AM »
Mr March; I assume you are far far far more familiar with Dr Woodward's nailing down spurious signals than I but I just got through that portion of his book. He basically nuked every potential source of spurious signal in his apparatus and because he is using a nearly identical set up until you get to the frustrum itself his analysis is germain to this project. He appears to have authoritatively disproved every thing we have considered here WRT spurious signals; leaving the problem of what the thrust signal really results from.

That does not give us the answer to what is going on but it does tell us what it is not.

I guess in replication everyone has to redo that work but I cannot help but feel that it is sort of a waste of time to do that all over again. likewise; since I am pretty sure Dr White and yourself know all about Dr Woodward's spurious signal source crushing that the Eagleworks team has also done the same.

I would therefore assume you guys are very confident you have something real and that it is not explained by mundane errors.
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Star-Drive

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Re: EM Drive Developments - related to space flight applications - Thread 2
« Reply #1531 on: 03/26/2015 11:44 AM »
Mr March; I assume you are far far far more familiar with Dr Woodward's nailing down spurious signals than I but I just got through that portion of his book. He basically nuked every potential source of spurious signal in his apparatus and because he is using a nearly identical set up until you get to the frustrum itself his analysis is germain to this project. He appears to have authoritatively disproved every thing we have considered here WRT spurious signals; leaving the problem of what the thrust signal really results from.

That does not give us the answer to what is going on but it does tell us what it is not.

I guess in replication everyone has to redo that work but I cannot help but feel that it is sort of a waste of time to do that all over again. likewise; since I am pretty sure Dr White and yourself know all about Dr Woodward's spurious signal source crushing that the Eagleworks team has also done the same.

I would therefore assume you guys are very confident you have something real and that it is not explained by mundane errors.

Stormbringer:

"Mr. March; I assume you are far far far more familiar with Dr Woodward's nailing down spurious signals than I but I just got through that portion of his book. He basically nuked every potential source of spurious signal in his apparatus and because he is using a nearly identical set up until you get to the frustrum itself his analysis is germain to this project."

As you probably know Dr. White and I would not be in this business if it were not for Dr. James F. Woodward's valiant efforts in first bringing to light in 1988 his Mach-Effect conjecture, gladly sharing his vision and knowledge with others like us, and then Jim's tireless efforts to experimentally prove his M-E conjecture while suffering through his stage-4 lung and other cancer treatments for the last nine years plus.  And you are also correct in saying that Dr. Woodward has addressed and/or corrected every known error source in his toque pendulum setup over the last 15 years.  In other words IMO Jim has a near bullet proof experimental test setup and Sonny and I have tried to use as much of Dr. Woodward's experimental insights on our test setup in the Eagleworks Lab's torque pendulum as was applicable.

"Likewise; since I am pretty sure Dr White and yourself know all about Dr. Woodward's spurious signal source crushing that the Eagleworks team has also done the same."

Jim Woodward and I have been talking through front and back channels since March of 1998 and continue to do so to this day as needed.  In fact my wife and I  stayed with Jim and his lovely wife Carole for a few days in his CO retreat during our summer break last August to be with good friends and to discuss his ongoing work and tell Jim about our project at Eagleworks Lab.  And we've tried to incorporate as much of this corporate knowledge that Dr. Woodward has developed over the years that my poor brain can assimilate, for Dr. Woodward is one brilliant experimenter to which I can only aspire to emulate.  However Dr. White and Dr. Woodward had a professional falling out back in 2007 when Sonny decided that the Mach-Effect was not the whole story and that the quantum mechanical aspects of this business had to be addressed as well, where Dr. Woodward was content to rely on just Special & General Relativity Theory and Wheeler/Feynman radiation reaction forces for his explanation for the observed data.

"I would therefore assume you guys are very confident you have something real and that it is not explained by mundane errors."

As we say in the lab, WE think there IS a there, there and yes, we feel quite strongly about that point and continue to build a case for the reality of the effects we've been able to bring to light and to find ways to scale them up in magnitude.  Of course whether the effects we are examining are just SRT/GRT based, or whether we have to also evoke known and obscure quantum effects and perhaps even new physics to explain these observed phenomenon is currently what's in play.  But in my opinion we will end up coming to terms with what the thing we call gravity really is by the time this project is finally put into the history books.

Best, Paul M.

Star-Drive

dustinthewind

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Re: EM Drive Developments - related to space flight applications - Thread 2
« Reply #1532 on: 03/26/2015 06:41 PM »
I still think we can violate newtons 3rd law in a way but in another way it is not violated because the propulsion device projects radiation out one end.  This looks like radiation propulsion but by sticking a dielectric between the two current loops we can change the speed of light making the two current loops closer or lowering the frequency needed while also getting near field effects?  What this does for the radiation projected I'm not exactly sure but I would assume it should intensify.  This is assuming none of the current loops have constant current but are both changing in time and out of phase pi/2 (see figure EM Propulsion 2.png).

I guess the idea was if there was something similar going on inside the radiation cavity though I can't quite say that there is.  There is also the issue of the idea that radiation projected is conserving momentum but this is inside a cavity.  (see figure EM Propulsion 3.png)

Edit: sorry, changed pi/4 to pi/2
« Last Edit: 03/26/2015 07:08 PM by dustinthewind »

Rodal

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Re: EM Drive Developments - related to space flight applications - Thread 2
« Reply #1533 on: 03/26/2015 07:09 PM »
...

Dr. Rodal:

I asked our first COMSOL analyst his opinion on this resonant mode naming issue and attached is Frank's comments on same.

Best, Paul M.
What a fantastic response !
Paul, please thank Frank for taking the time to write a comprehensive answer.

I think we have arrived to a full understanding and agreement.

I attach 3 plots below:

1) "First Mode TM011a (Eagleworks TM010 at 0.9598 GHz) Small Base at r=0.3008, Big Base at r=0.5294"

2) "Second Mode TM011b (Eagleworks TM011 at 1.3435 GHz) Small Base at r=0.3008, Big Base at r=0.5294"

3) "Third Mode TM012 (Eagleworks TM012 at 1.7160 GHz) Small Base at r=0.3008, Big Base at r=0.5294"

which show the magnetic field strength B at the conical wall (which takes place only in the azimuthal direction, since these are transverse magnetic modes) as a function of the spherical coordinate in the r direction defining the truncated cone (see image for the significance of "r"):

The last plot, for "Third Mode TM012 (Eagleworks TM012 at 1.7160 GHz)" shows that the mode shape for this mode is a full-wave pattern: or two half-wave patterns, therefore this mode should indeed be designated as TM012 in an analogy to a cylindrical cavity (because the last quantum number p=2 indicates the number of half-wave patterns in the longitudinal direction).  Thus, there is no doubt about this mode and we fully agree on this one.

The first two plots show that the first two modes both exhibit one half-wave pattern, therefore from that point of view they are both TM011 modes (because the last quantum number p=1 indicates the number of half-wave patterns in the longitudinal direction).  Since they are both TM011 modes, I will designate them TM011a and TM011b.

When the analyst is tasked with identifying the mode shapes that are closest to a cylindrical cavity I can fully see why Frank would identify TM011b as TM011, because TM011b exhibits a change of sign of the magnetic field going from the small base to the big base.  On the other hand, TM011a, although it has a changing magnetic field strength in the longitudinal direction (changing as a half-wave pattern), it does not change sign going from the small base to the big base.

What happens is very neat:

a) strictly speaking, the transverse magnetic field in a conical cavity cannot be constant, hence there cannot be a TM010 mode in a cone.  However, for cones that have a cone angle sufficiently small (that is: truncated cones that are close enough to a cylindrical cavity) there are two TM011 modes, the lowest TM011 mode is closest to a constant field, closest to TM010, and the higher TM011 mode is closest to a true TM011 mode. Exactly the same designation chosen by Frank: TM010 for TM011a and TM011 for TM011b.

b) For a cone angle approaching zero degrees (a cone approaching a cylindrical cavity) the magnetic field becomes constant in the longitudinal direction, and TM011a becomes TM010.  The same designation chosen by Frank.

c) For higher cone angles (for example for the example considered by Greg Egan http://gregegan.customer.netspace.net.au/SCIENCE/Cavity/Cavity.html) with a cone angle >= 20 degrees, the lower TM011 mode ("TM011a") disappears completely, as it is cut-off.
« Last Edit: 03/26/2015 07:47 PM by Rodal »

Rodal

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Re: EM Drive Developments - related to space flight applications - Thread 2
« Reply #1534 on: 03/26/2015 07:34 PM »
....
....

What happens is very neat:

a) strictly speaking, the transverse magnetic field in a conical cavity cannot be constant, hence there cannot be a TM010 mode in a cone.  However, for cones that have a cone angle sufficiently small (that is: truncated cones that are close enough to a cylindrical cavity) there are two TM011 modes, the lowest TM011 mode is closest to a constant field, closest to TM010, and the higher TM011 mode is closest to a true TM011 mode. Exactly the same designation chosen by Frank: TM010 for TM011a and TM011 for TM011b.

b) For a cone angle approaching zero degrees (a cone approaching a cylindrical cavity) the magnetic field becomes constant in the longitudinal direction, and TM011a becomes TM010.  The same designation chosen by Frank.

c) For higher cone angles (for example for the example considered by Greg Egan http://gregegan.customer.netspace.net.au/SCIENCE/Cavity/Cavity.html) and certainly for a cone angle > 30 degrees, the lower TM011 mode ("TM011a") disappears completely, as it is cut-off.

@Notsosureofit

The above discussion and plots are relevant to the extent that one can pursue an approximate formula for the truncated cone using a cylindrical cavity as a close analogue, as in your approximate formula.  It helps understand and quantify the approximation involved.

You can see from the plots that even for the NASA Eagleworks truncated cone differences appear for the lowest TM mode:  it is no longer constant in the longitudinal direction.  This lowest TM011a mode that looks like TM010 completely disappears for a cone angle >=20 degrees.

Although the magnetic field variation in the longitudinal direction for a cylindrical cavity goes like Cos[p Pi z/L] (where "p" is the quantum mode shape number in the longitudinal direction and z is the longitudinal coordinate and L the axial length of the cylindrical cavity), the longitudinal variation in the truncated cone with the NASA Eagleworks dimensions is a distorted wave-pattern (described by spherical Bessel functions and its derivative): it does no longer posses the symmetry of the Cosine function: mode shapes have a stronger field at one base than at the other base.
« Last Edit: 03/26/2015 07:51 PM by Rodal »

Notsosureofit

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Re: EM Drive Developments - related to space flight applications - Thread 2
« Reply #1535 on: 03/26/2015 07:55 PM »
@ RODAL

tchernik

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Re: EM Drive Developments - related to space flight applications - Thread 2
« Reply #1536 on: 03/26/2015 08:23 PM »
Good to see this discussion is still moving into interesting directions.

As an interested but ignorant person in the Internet, what I take from the last posts, is that the effect (if it indeed exists) could be strongly affected by the geometry of the truncated cone cavity (e.g. the slope angle), which strongly impacts the resonance modes and frequencies producing them.

Does that  mean that not any cone shape would do? and that for every shape, there is a probably small set of frequencies for which the right resonating modes would arise?

It would be interesting to know which geometries and frequencies produce the best force results... something maybe R. Shawyer has a lot more experience in, given he has been tinkering with this for years and maybe decades.

That characterization is potentially very interesting for anyone else trying replications, because without taking that into account and assuming the phenomenon does exist, some may see something, others may see nothing at all, or just something below the force measurement noise.

Notsosureofit

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Re: EM Drive Developments - related to space flight applications - Thread 2
« Reply #1537 on: 03/26/2015 08:31 PM »
It's the unending search for the perfect shape giving maximum thrust !
« Last Edit: 03/26/2015 08:31 PM by Notsosureofit »

Rodal

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Re: EM Drive Developments - related to space flight applications - Thread 2
« Reply #1538 on: 03/26/2015 09:48 PM »
I still think we can violate newtons 3rd law in a way but in another way it is not violated because the propulsion device projects radiation out one end.  This looks like radiation propulsion but by sticking a dielectric between the two current loops we can change the speed of light making the two current loops closer or lowering the frequency needed while also getting near field effects?  What this does for the radiation projected I'm not exactly sure but I would assume it should intensify.  This is assuming none of the current loops have constant current but are both changing in time and out of phase pi/2 (see figure EM Propulsion 2.png).

I guess the idea was if there was something similar going on inside the radiation cavity though I can't quite say that there is.  There is also the issue of the idea that radiation projected is conserving momentum but this is inside a cavity.  (see figure EM Propulsion 3.png)

Edit: sorry, changed pi/4 to pi/2
There are many things to discuss here.

Of course  the electric field and magnetic fields are two interrelated aspects of a single object: the electromagnetic field tensor in 3D+1=4 spacetime.

But if your loops and images are to be interpreted literally only in terms of electric current loops, please notice that your image then could be interpreted as saying that only TE (transverse electric) modes would produce the effect you are seeking, because only TE modes have the electric field in the azimuthal (circumferential) direction.  But notice that NASA Eagleworks is currently successfully testing in a vacuum TM modes (and actually I understand they have a preference for TM modes), for which the magnetic field B has a component only in the azimuthal (circumferential) direction while the electric field E has components perpendicular to the magnetic B field.  The electric field has zero component in the circumferential direction for TM modes.
« Last Edit: 03/27/2015 12:13 AM by Rodal »

Rodal

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Re: EM Drive Developments - related to space flight applications - Thread 2
« Reply #1539 on: 03/27/2015 12:43 AM »
Struck out on finding a lathe to use. My belt sander did a fantastic job too. So now I have 2, 1" thick x 6.25" wide HDPE discs. Now I have to figure out how to mount them....

Where there's a will, there's a way.

QUESTION 1: Before mounting the discs, could you please run a couple of tests without the HDPE discs?

If, so I can send you a post showing the mode shapes at the two frequencies near 2.45 GHz and why .

There is a mode shape at 2.49 GHz (or at 2.46 GHz according to NASA's COMSOL calculations) that should produce no force without the dielectric disc (because the Poynting vector practically cancels out)

There is a mode shape at 2.46 GHz (or at 2.41 GHz according to NASA's COMSOL calculations) that may produce an electromagnetic force without the dielectric disc (because the Poynting vector does not cancel out)

...

So here is the data:

All cases: empty cavity, NO polymer dielectric inside

Mode        Frequency (GHz) [Exact sltn.]     Frequency (GHz) [COMSOL FEA]       Poynting Vector
Cyl. TM311    2.45835                                      2.4068                                                Towards Small Base
Cyl. TM212    2.49342                                      2.4575                                                 ~ 0

Notice:

1)  (ExB) is a quadratic function of the harmonic function Cos[ ω t], such that the variation with time goes like (Cos[ ω t])^2 so that it never changes sign and therefore does not change orientation with time, even for this AC field.

2) The Poynting  vector field changes magnitude around the circumference (the "azimuthal direction" which is perpendicular, "out of the plane of the truncated cone section").  At the azimuthal angle φ=0 (and multiples of it), the Poynting vector component perpendicular to the cone's curved walls is more than 3 times larger than the Poyting vector component in the longitudinal ("radial") direction of the cone.  Since the  Poynting vector component perpendicular to the cone's curved walls is self-cancelling, all that is left is the radial component (which is also shown).

3) At azimuthal angle φ=45 degrees (and multiples) the Poynting vector component perpendicular to the cone's curved walls is zero,  The only Poynting vector component at those angles is directed in the radial direction.

4) The finite element analysis (FEA) solution converges "from below".  As the finite element mesh is made finer (more finite elements are used), the finite element solution becomes less stiff and it approaches the exact solution.  Hence the frequency calculated by FEA is always lower than the exact solution frequency for a finite mesh.

5) The exact solution assumes that the small and big bases are spherical sections (which is the ideal shape because the electromagnetic waves are spherical inside a cone).   The actual geometry used by NASA Eagleworks and modeled by COMSOL FEA is flat surfaces both for the small and big bases of the truncated cone.

6) The exact solution takes less than 3 seconds to calculate in a PC, much less time than what a Finite Element Solution takes.
« Last Edit: 03/27/2015 12:36 PM by Rodal »

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