Author Topic: EM Drive Developments - related to space flight applications - Thread 2  (Read 2170987 times)

Offline Rodal

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Out of interest have any of Eagleworks results appeared on arXiv?
I saw that in the article.  I didn't bother to check because anyone can publish anything on arXiv:

ArXiv is now moderated (it wasn't at the beginning).

ArXiv has this disclaimer:  "The moderators are not referees and do not provide detailed feedback on submissions."

ArXiv is not a refereed, peer reviewed process.

What an academic would inquire is about the number of times that an article has been cited in peer reviewed journals.

In any case, how many peer-reviewed papers did Edison publsh ?
Did Edison publish in ArXiv ?
« Last Edit: 05/06/2015 11:34 PM by Rodal »

Offline SeeShells

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I may be just an engineer but over the 40 years of my career I've plenty of unexplained things in designs. Anyone taken into consideration the thermal expansion coefficient of the EM case during your pulsed phase? I've been reading for days and there is so much material I might have missed it. Sorry if I did.

Offline Rodal

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I may be just an engineer but over the 40 years of my career I've plenty of unexplained things in designs. Anyone taken into consideration the thermal expansion coefficient of the EM case during your pulsed phase? I've been reading for days and there is so much material I might have missed it. Sorry if I did.

Yes, see this analysis by one of the people in this forum:

https://www.researchgate.net/publication/268804028_NASA%27S_MICROWAVE_PROPELLANT-LESS_THRUSTER_ANOMALOUS_RESULTS_CONSIDERATION_OF_A_THERMO-MECHANICAL_EFFECT

Offline WarpTech

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<snip>
The conclusions of Egan are correct when only considering radiation pressure at wavelength's that are short compared to the cut-off modes. They are incorrect because he did not take into consideration the variable speed of light inside the waveguide for wavelengths close to the cut-off modes. He used eps0 and mu0 as the permittivity and permeability of free vacuum in all his calculations of energy density and force. That is an error!

The space inside the waveguide is not free vacuum, it is constrained by the waveguide. Near the cut-ff modes, his calculations are invalidated because the speed of light is not the same throughout the cavity.

Best Regards,
Todd D.

...The correct statement is that any solution solely based on Maxwell's equations (like Greg Egan's analysis) predicts no thrust, and that therefore the measurements at NASA Eagleworks are due to something else not addressed by Maxwell's equations.

Todd, your explanation uses General Relativity and the Quantum Vacuum, which are explicitly not addresed by Greg Egan.  His solution is still mathematically exact (solution of Maxwell's equations), it may just not be representing the actual physical tests. Either because the tests are an artifact or because they represent some form of propulsion that may be explained by your model or other alternative models.

On the other hand what is mathematically incorrect would be to state that a solution solely based on Maxwell's equation and special relativity (without invoking GR, or the QV, or something else) can predict a thrust in a closed cavity: that is plainly mathematically incorrect.  Something else is needed besides Maxwell's equations and special relativity.

I hope yours (or another theory) succeeds in explaining the measurements as something that can be used for space propulsion, or that it is an artifact.  But the experimental measurements cannot be explained solely based on Maxwell's equations and special relativity.

 :)

...

Agreed. I believe they would be addressed by Maxwell's questions in curved space-time perfectly well, if a metric were included to account for the variable speed of light, at certain wavelengths.

I do not think there is any "new" physics here to be discovered. It's just new understanding and interpretation;

1. We "know" from Shawyer and textbook physics that the speed of light inside a waveguide depends on the wavelength of the microwaves, and the diameter of the waveguide.

2. We "know" from the PV Model interpretation of GR and observations of gravitational lensing, that a gravitational field is a variable refractive index where the speed of light is not a constant.

3. Therefore, the logical next step is to write Egan's formulation in a generally covariant form and apply a frequency dependent space-time metric, to model the variable refractive index of the tapered waveguide at specific frequency modes.

Personally, I'm not very good at writing generally covariant equations correctly, but I'll give it a shot of there are no GR'ist here who could do this for us. To me, it's simply Shawyer's equation;

Let J1 and J2 be two separate 4-current densities
Let F1 and F2 be the Maxwell field tensor for each.
The force density;

f = J1*F2 - J2*F1 = 0  in flat space-time

It does not equal zero in curved space-time because there is a metric in each product, that has a different value in each location. Shawyer is right in this regard, but I'm no better at the covariant equations than he is.

Thank you!

Best Regards,
Todd
« Last Edit: 05/06/2015 07:47 PM by WarpTech »

Offline TheTraveller

...
DO NOT reinvent the wheel.

Follow Shawyer as close as you can.

Plenty of clues but you need to do a lot of reading.

....

You are writing that in reference to Shaywer's experiments, I presume, but a number of Shawyer's prescriptions are tied to his theoretical model.  I read the paper that Shawyer sent to Mulletron, to support Shawyer's theoretical model.

I wrote a review of this paper here:  http://forum.nasaspaceflight.com/index.php?topic=36313.msg1369861#msg1369861

Showing that there is nothing in that paper (by Cullen) supporting Shawyer's theoretical model.  On the contrary, it follows the same Maxwell's equations and laws followed by Greg Egan http://gregegan.customer.netspace.net.au/SCIENCE/Cavity/Cavity.html  who concludes that the EM Drive should have no thrust force.
I did read your review that there should be no thrust. But there seems to be thrust, of a level and direction which agrees with Shawyer's theory. Which is why the Shawyer and Chinese thrust claims need to be experimentally verified or not.

I believe there is enough data in the public domain to experimentally replicate their test setups, cavity designs and RF generation / feed methods, starting with the RF narrow band, spherical end plate Flight Thruster, feed via coax, which I plan to replicate in copper and if necessary in Alumininum.

...

No, my review never states that there should be no thrust in the experimental results. 

My review instead states (and shows, carefully, point by point) that the reference given by Shawyer to support his theoretical model, does NOT support his model at all.

Therefore I do not understand why Shawyer references Cullen's paper.

As a reductio ad absurdum, it would be almost like Shawyer referencing Greg Egan, and sending Greg Egan's analysis as support for Shawyer's theoretical explanation.
With respect, your theory.

Shawyer has his & says the EM Drive gens thrust as per his theory based calcs.

For me I will build what Shawyer claims works. I'm fairly certain I have the engineering / experimentalists skills to make it work, if it can work. If it produces thrust, you and anyone else will be welcome to visit and test it yourself. Might even add Shawyer, Paul March & Dr. White to the invite list. Would be interesting watching the 4 of you poke and prod the test unit, arguing the strengths and weaknesses of each others theories.
"As for me, I am tormented with an everlasting itch for things remote. I love to sail forbidden seas.
Herman Melville, Moby Dick

Offline Rodal

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...
Let F1 and F2 be the Maxwell field tensor for each.
The force density;

f = J1*F2 - J2*F1 = 0  in flat space-time

It does not equal zero in curved space-time because there is a metric in each product, that has a different value in each location. Shawyer is right in this regard, but I'm no better at the covariant equations than he is.

Thank you!

Best Regards,
Todd

Regarding the force summation by Shawyer, what happened to the force vector components on the lateral, conical  surfaces?  Why is it that only  the forces on the end plates (the bases of the truncated cone) are being addressed?

If one includes the forces on the lateral conical surfaces everything sums to zero (solely using Maxwell's equations)
« Last Edit: 05/06/2015 08:09 PM by Rodal »

Offline TheTraveller

I may be just an engineer but over the 40 years of my career I've plenty of unexplained things in designs. Anyone taken into consideration the thermal expansion coefficient of the EM case during your pulsed phase? I've been reading for days and there is so much material I might have missed it. Sorry if I did.
Ditto on the engineering years and seeing strange things. Been there, seen that.

Shawyers Teeter-Totter test system, with the cavity oriented vertically and supported on 4 external rods, virtually eliminates effects from thermal expansion and COG movement. Is what I will build. Rough sketch here. Like Shawyers 1st test unit sitting on one end of a wide Teeter Totter balance system.

RF coax will feed up through a hole in the centre of the Teeter Totter instead of the method shown on the sketch. 0.5kg scale with 0.001g sensitivity will be on the other end, not directly under the EM Drive. Want to remove any electronics from near the EM Drive.
« Last Edit: 05/06/2015 07:59 PM by TheTraveller »
"As for me, I am tormented with an everlasting itch for things remote. I love to sail forbidden seas.
Herman Melville, Moby Dick

Offline Mulletron

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Enjoyed reading the comments from Davis and Millis. More replication attempts to come. The race has begun.  :)
Challenge your preconceptions, or they will challenge you. - Velik

Offline TheTraveller

Enjoyed reading the comments from Davis and Millis. More replication attempts to come. The race has begun.  :)
If we hang together and openly share info, we can make this happen.
"As for me, I am tormented with an everlasting itch for things remote. I love to sail forbidden seas.
Herman Melville, Moby Dick

Offline Rodal

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...
It does not equal zero in curved space-time because there is a metric in each product, that has a different value in each location. Shawyer is right in this regard, but I'm no better at the covariant equations than he is.

...
I think we (people reading this) can write the covariant equations. The equations would be nonlinear, and therefore an exact solution would prove impossible to obtain for the truncated cone. How would you proceed ?  via a perturbation analysis (if so in terms of what dimensionless parameter?) or via a numerical solution?

EDIT :1)  I think the motivation would increase if there would be an answer to the energy paradox (what restricts the energy paradox for constant acceleration at constant power ?)

and this also needs to be addressed:

2) Regarding the force summation by Shawyer, what happened to the force vector components on the lateral, conical  surfaces?  Why is it that only  the forces on the end plates (the bases of the truncated cone) are being addressed? If one includes the forces on the lateral conical surfaces everything sums to zero (solely using Maxwell's equations)
« Last Edit: 05/06/2015 08:12 PM by Rodal »

Offline StrongGR

...
It does not equal zero in curved space-time because there is a metric in each product, that has a different value in each location. Shawyer is right in this regard, but I'm no better at the covariant equations than he is.

...
I think we (people reading this) can write the covariant equations. The equations would be nonlinear, and therefore an exact solution would prove impossible to obtain for the truncated cone. How would you proceed ?  via a perturbation analysis (if so in terms of what dimensionless parameter?) or via a numerical solution?

EDT : I think the motivation would increase if there would be an answer to the energy paradox (what restricts the energy paradox for constant acceleration at constant power ?)

The non-linear set of Einstein-Maxwell equations has exact solutions for plane waves. You can apply it to a schematic of a laser beam transiting in a cavity having the form of a cube without difficulty. A plane wave always deforms space-time and a cavity has the advantage that the energy of the field depends also on the Q factor that can increase it by orders of magnitude. This means that an explanation for the question of the behaviour of the laser beam inside the cavity can be easily at hand. For the other question, the thrust, as a physicist I keep on being rather sceptical because I tried to move my car by hitting the windscreen with punches and nothing happened.

I will post here the solution for a very simple set-up of a cube cavity maintaining a single mode and show the way the laser beam propagates inside it. This resonant cavity seems to be very good for engineering of space-time rather than else.

Offline Rodal

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...
It does not equal zero in curved space-time because there is a metric in each product, that has a different value in each location. Shawyer is right in this regard, but I'm no better at the covariant equations than he is.

...
I think we (people reading this) can write the covariant equations. The equations would be nonlinear, and therefore an exact solution would prove impossible to obtain for the truncated cone. How would you proceed ?  via a perturbation analysis (if so in terms of what dimensionless parameter?) or via a numerical solution?

EDT : I think the motivation would increase if there would be an answer to the energy paradox (what restricts the energy paradox for constant acceleration at constant power ?)

The non-linear set of Einstein-Maxwell equations has exact solutions for plane waves. You can apply it to a schematic of a laser beam transiting in a cavity having the form of a cube without difficulty. A plane wave always deforms space-time and a cavity has the advantage that the energy of the field depends also on the Q factor that can increase it by orders of magnitude. This means that an explanation for the question of the behaviour of the laser beam inside the cavity can be easily at hand. For the other question, the thrust, as a physicist I keep on being rather sceptical because I tried to move my car by hitting the windscreen with punches and nothing happened.

I will post here the solution for a very simple set-up of a cube cavity maintaining a single mode and show the way the laser beam propagates inside it. This resonant cavity seems to be very good for engineering of space-time rather than else.
OK, I agree with what you state above.

However, what these experimenters claim, is that without a dielectric polymer insert, the thrust is only produced by a conical cavity (a truncated cone)  .  They claim that a cavity with constant cross-section will produce no thrust (unless it includes a dielectric section inside it).

So what what would be great to have  :)


1)  the solution for a very simple set-up of a constant cross-section cavity (containing an insert of a polymer dielectric and the rest of the cavity void) maintaining a single mode and show the way the laser beam propagates inside it

or

2)  the solution for a truncated cone

__________

#1 (constant cross-section cavity containing a polymer dielectric in part of the cavity) would be most useful to the group in California and to one of our members (@notsosureofit) who has been looking at such a solution and also was planning testing using a Gunn diode cavity
« Last Edit: 05/06/2015 11:36 PM by Rodal »

Offline Star One

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I've noticed that there is a number of people now attempting to do their own builds, as has mentioned elsewhere, is there any danger to themselves in this? By the way I'm not attempting to cast aspersions on anyone's technical abilities by asking this I'm just genuinely wondering?

Offline sghill

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I will post here the solution for a very simple set-up of a cube cavity maintaining a single mode and show the way the laser beam propagates inside it. This resonant cavity seems to be very good for engineering of space-time rather than else.

May I respectfully ask that you also include a visualization of the solution if possible?  I'd very much like to see this.
Bring the thunder Elon!

Offline D_Dom

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RF energies can cause severe burns.
http://rfsafetysolutions.com/RF%20Radiation%20Pages/Biological_Effects.html
"Perhaps the most vulnerable organs are the eyes. The eyes have virtually no blood flow that can provide cooling from other parts of the body, and their dimensions make them very good antennas at microwave frequencies."
Space is not merely a matter of life or death, it is considerably more important than that!

Offline Rodal

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I will post here the solution for a very simple set-up of a cube cavity maintaining a single mode and show the way the laser beam propagates inside it. This resonant cavity seems to be very good for engineering of space-time rather than else.

May I respectfully ask that you also include a visualization of the solution if possible?  I'd very much like to see this.
StrongGR  may be talking about a closed-form solution for that case (without the dielectric insert), therefore a mathematical formula.  Not necessarily including plots, as they are necessary for numerical solutions. 

Given the closed-form solution (for which we would be most thankful  :) ) then all of us could make plots using our own software, for any numerical values we are interested in.

That's why closed-form solutions rock :)
« Last Edit: 05/06/2015 11:36 PM by Rodal »

Offline aceshigh

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Enjoyed reading the comments from Davis and Millis. More replication attempts to come. The race has begun.  :)

are you saying that Marc Millis and Eric Davis are posting directly here at NSF forum?? Under what nicknames?

if so, I wonder if Dr Davis could clear out the doubts we had regarding the light cone issue from his talk at Icarus Interstellar Starship Conference (2013), at page 93 of this thread.
« Last Edit: 05/06/2015 08:58 PM by aceshigh »

Offline WarpTech

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...
It does not equal zero in curved space-time because there is a metric in each product, that has a different value in each location. Shawyer is right in this regard, but I'm no better at the covariant equations than he is.

...
I think we (people reading this) can write the covariant equations. The equations would be nonlinear, and therefore an exact solution would prove impossible to obtain for the truncated cone. How would you proceed ?  via a perturbation analysis (if so in terms of what dimensionless parameter?) or via a numerical solution?

EDIT :1)  I think the motivation would increase if there would be an answer to the energy paradox (what restricts the energy paradox for constant acceleration at constant power ?)

and this also needs to be addressed:

2) Regarding the force summation by Shawyer, what happened to the force vector components on the lateral, conical  surfaces?  Why is it that only  the forces on the end plates (the bases of the truncated cone) are being addressed? If one includes the forces on the lateral conical surfaces everything sums to zero (solely using Maxwell's equations)

This is at the limit of my mathematical abilities, but I would perturb the refractive index as the dimensionless parameter. It is the same as a perturbation of the metric coefficients, as a small deviation from Minkowski's metric, eta^uv.

g^uv = eta^uv + h^uv

The h^uv represent the variations of c/K in the waveguide, and will need to be experimentally determined over specific frequencies and bandwidths to find out what those components "really" are. In this case, the non-linearity will appear in the B-H and D-E curves of the waveguide, but a linear approximation of a metric, the way it is done for gravitational waves, should suffice if the cone angle is small.

Regarding the energy paradox.

Power = Force * Velocity
Acceleration = Force / Mass = Power / Momentum

Therefore, as the momentum increases, the acceleration decreases for a constant power input. That's without relativistic effects. Why is this a paradox? You've mentioned this a few times, but I guess I've missed something.

Regarding Shawyer's analysis. I do not agree with the formulation, it is a layman's approximation. What I agree with is that the difference in group velocity "is" the reason it works. He's right about that. His formulation is not the generally covariant one it should be, as I described. Again, using Maxwell's equations in a curved space-time with a frequency dependent metric.

Best Regards,
Todd D.


Offline deltaMass

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I may be just an engineer but over the 40 years of my career I've plenty of unexplained things in designs. Anyone taken into consideration the thermal expansion coefficient of the EM case during your pulsed phase? I've been reading for days and there is so much material I might have missed it. Sorry if I did.

Yes, see this analysis by one of the people in this forum:

https://www.researchgate.net/publication/268804028_NASA%27S_MICROWAVE_PROPELLANT-LESS_THRUSTER_ANOMALOUS_RESULTS_CONSIDERATION_OF_A_THERMO-MECHANICAL_EFFECT
That's an excellent analysis - Kudos. I would not be surprised if you were a small numerical factor in error (as I'm sure neither would you be) and as such you're pointing up the possibility of all the measured thrust being attributable to thermally-induced movement.

And of course, the measurement of a reverse thrust does not gainsay the thermal explanation, since everything will be thermally perturbed in the opposite direction when the cavity is mounted 180o to its default mounting orientation.

Mr. March counters this with the fact that the measured thrust onset is as prompt as that of the calibration pulse. Yet you are showing quite prompt thermal onsets. How do you reconcile these two points of view?
« Last Edit: 05/06/2015 09:06 PM by deltaMass »

Offline deltaMass

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Regarding the energy paradox.

Power = Force * Velocity
Acceleration = Force / Mass = Power / Momentum

Therefore, as the momentum increases, the acceleration decreases for a constant power input. That's without relativistic effects. Why is this a paradox? You've mentioned this a few times, but I guess I've missed something.

Best Regards,
Todd D.

No.  You are conflating input power and output power here. Please see my analysis.
http://forum.nasaspaceflight.com/index.php?topic=36313.msg1369875#msg1369875
The EmDrive is not a tyre and spacetime is not the road upon which it rides.

If you propose that an EmDrive accelerating in free space exhibits thrust which depends somehow on its velocity, then what you propose violates special relativity.
« Last Edit: 05/06/2015 10:11 PM by deltaMass »

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