Author Topic: EM Drive Developments - related to space flight applications - Thread 2  (Read 2165505 times)

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
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?

Thermal buckling is extremely dependent on initial imperfections, thus it is highly unlikely that it can be the only explanation for multiple tests at multiple locations with multiple specimens.

Therefore something else is at play here.

Pressure measurements due to radiation have been plagued with air convection currents for 140 years.
None of the experimenters have used Cullen's set-up in ambient conditions: nobody has used concentric rings (see this  http://forum.nasaspaceflight.com/index.php?topic=36313.msg1370479#msg1370479 )

NASA Eagleworks is the only one that has conducted tests in a vacuum.  Their results could be due to outgassing from the fiberglass-reinforced-epoxy end-plate.

Therefore I highly advise that they should replace the end plates with concentric rings to rule out false positives, as done by Cullen in 1951, the first person to accurately measure microwave radiation pressure from microwaves.
« Last Edit: 05/06/2015 09:22 PM by Rodal »

Offline deltaMass

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Rodal: " Their results could be due to outgassing from FRP4"

This is some sort of fibreglass?

Offline RotoSequence

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Rodal: " Their results could be due to outgassing from FRP4"

This is some sort of fibreglass?

The Eagleworks EM Drive backplate is copper coated, fiberglass reinforced polymer of the type used to make printed circuit boards.

Offline Rodal

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Rodal: " Their results could be due to outgassing from FRP4"

This is some sort of fibreglass?

Bilayer: an external thick layer of Fiberglass-reinforced-epoxy end-plate with an extremely thin layer of copper deposited on the inner surface of the truncated cone end plate

Offline deltaMass

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I have not seen descriptions of EagleWorks' vacuum outgassing/bake-out protocols.

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.

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?

Thermal buckling is extremely dependent on initial imperfections, thus it is highly unlikely that it can be the only explanation for multiple tests at multiple locations with multiple specimens.

Therefore something else is at play here.

Pressure measurements due to radiation have been plagued with air convection currents for 140 years.
None of the experimenters have used the proper test set-up in ambient conditions: nobody has used concentric rings (see this  http://forum.nasaspaceflight.com/index.php?topic=36313.msg1370479#msg1370479 )

Only NASA Eagleworks is the only one that has conducted tests in a vacuum.  Their results could be due to outgassing from the fiberglass-reinforced-epoxy end-plate.

Therefore I highly advise that they should replace the end plates with concentric rings to rule out false positives, as done by Cullen in 1951, the first person to accurately measure microwave radiation pressure from microwaves.
Would be interested in testing that idea. AFTER either no thrust or thrust is found.

"Follow the Data, Ignore the 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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That's not a theory!

That was the first accurate, successful experimental measurement of microwave pressure, and Cullen learnt that by first trying a solid end plate (which resulted in false-positive due to air currents), it was his PhD thesis   :)

Cullen's Ph.D. thesis is an experiment to measure radiation pressure from microwaves.

Just like Michelson's was an experiment, and Cavendish was an experiment, and so on and on.


« Last Edit: 05/06/2015 09:34 PM by Rodal »

Offline PaulF

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Question to all:

Has quantum tunneling been incorporated in any calculations? I read once that at least some photons will tunnel through the medium of the cavity walls. Hope this sparks something in someone's mind.
Yes, we considered it.  It would become an inefficient photon rocket, as only a few of the photons would tunnel and the beam would not be perfectly collimated.  Hence it would not explain a claimed thrust/PoweInput thousands of times greater than a perfectly collimated photon rocket.
But what if... lets assume the theory of the thrusting of virtual particles. What if they also were able to tunnel and end up outside the cavity before they do whatever they normally do?

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.

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?

I'm slowly digging through the nice thermal expansion write-up, nice work. I was wondering if you have an IR camera and pics to back your calculations, as I'd like to see the thermal increases not only on the endcap but on the sides of the EM chamber. Thanks Guys!
 

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
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?

I'm slowly digging through the nice thermal expansion write-up, nice work. I was wondering if you have an IR camera and pics to back your calculations, as I'd like to see the thermal increases not only on the endcap but on the sides of the EM chamber. Thanks Guys!

These are the thermal measurements vs. thermal and electromagnetic field analysis (COMSOL FEA) for NASA Eagleworks for the experiments in a partial vacuum  ;) :

http://forum.nasaspaceflight.com/index.php?action=dlattach;topic=36313.0;attach=634723

The thermal distribution is clearly due to induction heating from the magnetic field, as expected.

My exact solution (elsewhere in other posts) for the magnetic field, for the electric field, confirms that the numerical solution using COMSOL FEA is within 1% of the exact solution, they used a good finite element mesh discretization and the numerical solution is practically converged to the exact result.

Also Prof. Juan Yang's reported temperature vs. time measurements with embedded thermocouples throughout their EM Drive cavity (without a polymer dielectric insert) under atmospheric conditions, that, curiously, show the highest temperature at the center of the small base (trace #1), followed, at a significantly lower temperature by the temperature at the periphery of the big base (trace #5).





Notice how much higher temperature is present in the Chinese (Yang) experiments.
Shawyer has not reported graphical information on thermal measurements for his experiments, to my knowledge.
I suspect same problem for Shawyer's experiments: huge thermal effects for Yang and Shawyer.

Also, tan delta out-of-phase losses in these cavities are not zero,particularly in NASA's dielectric polymer insert: the reported experiments show that the tan delta values of the materials used in these cavities is consistent with real materials experiencing out-of-phase dissipation (therefore one must use the complex form of the physical properties and not neglect the imaginary part if one is interested in assessing the finite value of Q, for example).

« Last Edit: 05/06/2015 10:48 PM by Rodal »

Offline WarpTech

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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.

Special Relativity does not apply to accelerating reference frames, which is what is being described here. Accelerated reference frames "are" preferred frames because they can be distinguished from one another, unlike inertial frames.

If F = P*k

Then the work done is the integral;

W = integral[Pin*k*v]*dt   from t=0 to t2.

Pout = dW/dt = Pin*k*v, Since Pin = Pout, k = 1/v.

The Power in will equal the Power out, the Work done will be the integration of Force * distance. Acceleration is not constant with constant Power input. I have a hunch that there is a hidden assumption in your derivation that acceleration is constant, so you get over-unity results. This needs to be considered like a Power Transformer. Power in = Power out.

That's my 2 cents worth.

Todd D.


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.

Quote from: deltaMass
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.

Quote from: WarpTech
Special Relativity does not apply to accelerating reference frames, which is what is being described here. Accelerated reference frames "are" preferred frames because they can be distinguished from one another, unlike inertial frames.
If F = P*k
 

There is no "if" about it. Note my use of a colon to indicate definition.
I define k := F/P   in Newtons/Watt

Quote from: WarpTech
Then the work done is the integral;
W = integral[Pin*k*v]*dt   from t=0 to t2.
Pout = dW/dt = Pin*k*v
Since Pin = Pout, k = 1/v

Same mistake as before. You are starting with the implicit assumption that Pin = Pout.
It is no surprise that you conclude the same.

Quote from: WarpTech
The Power in will equal the Power out, the Work done will be the integration of Force * distance. Acceleration is not constant with constant Power input.
I have a hunch that there is a hidden assumption in your derivation that acceleration is constant, so you get over-unity results.

Hidden? No. It's clearly stated in my preamble that acceleration will be constant.
More to the point, if you think there's a flaw in my maths, I'd like to hear specifics.

Quote from: WarpTech
This needs to be considered like a Power Transformer. Power in = Power out.
That's my 2 cents worth.

Todd D.

Offline Rodal

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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.

Special Relativity does not apply to accelerating reference frames, which is what is being described here. Accelerated reference frames "are" preferred frames because they can be distinguished from one another, unlike inertial frames.

If F = P*k

Then the work done is the integral;

W = integral[Pin*k*v]*dt   from t=0 to t2.

Pout = dW/dt = Pin*k*v, Since Pin = Pout, k = 1/v.

The Power in will equal the Power out, the Work done will be the integration of Force * distance. Acceleration is not constant with constant Power input. I have a hunch that there is a hidden assumption in your derivation that acceleration is constant, so you get over-unity results. This needs to be considered like a Power Transformer. Power in = Power out.

That's my 2 cents worth.

Todd D.

Thanks !

Since the quick trip scenarios presented by Dr. White in his papers (that were paraphrased in the NSF article) assumed a constant acceleration under constant power, it looks like that there are two alternatives here:


1) At speeds v <<c; F = P/v => m a = P/v => a = P/(m*v) therefore at constant power the acceleration is inversely proportional to the speed.  Equivalently for constant acceleration the power needs to be increased proportional to the speed.  Therefore the real performance of the EM Drive (for interplanetary missions or for going to Alpha Centauri) is much, much inferior to the calculations in White papers, and White with Joosten, etc. and they need to revisited.

or

2) as Paul March proposes, White's QV theory is the other side of the same coin as Woodward's Mach Effect,

https://en.wikipedia.org/wiki/Woodward_effect#Quantum_mechanics

for which they assume constant acceleration at constant power, and the energy paradox has to be formulated in terms of the inertial mass of Woodward instead.  (All kinds of questions here remaining to be answered: is Woodward conjecture a real effect? is the EM Drive "thrust" due to Woodward Mach Effect? is there an energy paradox for Woodward's effect ?)
« Last Edit: 05/07/2015 12:01 AM 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.

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?

I'm slowly digging through the nice thermal expansion write-up, nice work. I was wondering if you have an IR camera and pics to back your calculations, as I'd like to see the thermal increases not only on the endcap but on the sides of the EM chamber. Thanks Guys!

These are the thermal measurements vs. thermal and electromagnetic field analysis (COMSOL FEA) for NASA Eagleworks for the experiments in a partial vacuum  ;) :

http://forum.nasaspaceflight.com/index.php?action=dlattach;topic=36313.0;attach=634723

The thermal distribution is clearly due to induction heating from the magnetic field, as expected.

My exact solution (elsewhere in other posts) for the magnetic field, for the electric field, confirms that the numerical solution using COMSOL FEA is within 1% of the exact solution, they used a good finite element mesh discretization and the numerical solution is practically converged to the exact result.

Also Prof. Juan Yang's reported temperature vs. time measurements with embedded thermocouples throughout their EM Drive cavity (without a polymer dielectric insert) under atmospheric conditions, that, curiously, show the highest temperature at the center of the small base (trace #1), followed, at a significantly lower temperature by the temperature at the periphery of the big base (trace #5).





Notice how much higher temperature is present in the Chinese (Yang) experiments.
Shawyer has not reported graphical information on thermal measurements for his experiments, to my knowledge.
I suspect same problem for Shawyer's experiments: huge thermal effects for Yang and Shawyer.

Also, tan delta out-of-phase losses in these cavities are not zero,particularly in NASA's dielectric polymer insert: the reported experiments show that the tan delta values of the materials used in these cavities is consistent with real materials experiencing out-of-phase dissipation (therefore one must use the complex form of the physical properties and not neglect the imaginary part if one is interested in assessing the finite value of Q, for example).

Thank You for taking your time to answer me! I've got a little to digest here, but there is more than enough.
Is there any reason no one has used a simple copper mesh for the EM chamber?

Offline deltaMass

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It's good that at least one person understands what I'm on about. :-\

Consider an EmDrive in free space and accelerating. We switch it off temporarily and let it coast at speed v relative to the inertial frame in which it began its acceleration. When we switch it back on, are we going to assert that somehow the thrust F  knows what speed it's going and adjusts the thrust like F = P/v?

I assert again that this kind of thinking requires a preferred frame, and thus violates SR.
« Last Edit: 05/07/2015 12:07 AM by deltaMass »

Offline Rodal

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....
Thank You for taking your time to answer me! I've got a little to digest here, but there is more than enough.
Is there any reason no one has used a simple copper mesh for the EM chamber?

Excellent question.  I think an answer is found by looking at the last pages: although there are a couple of posts detailing that Cullen (the first person to successfully measure the microwave radiation pressure in his PhD experiments) solved the thermal convection problem by using a mesh, there are countless replies here saying "Theories are theories.  I will do exactly the same thing as Shawyer. "  :)  In other words: some experimenters may be initially doing what Shawyer did.  Shawyer did not use a mesh.

I bet that Paul  March would try the mesh and report on his results (just like he did the test with the unit outside the vacuum chamber to eliminate the issue of evanescent wave coupling once we discussed it in this forum)
« Last Edit: 05/07/2015 01:10 AM by Rodal »

Offline Rodal

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It's good that at least one person understands what I'm on about. :-\

Consider an EmDrive in free space and accelerating. We switch it off temporarily and let it coast at speed v relative to the inertial frame in which it began its acceleration. When we switch it back on, are we going to assert that somehow the thrust F  knows what speed it's going and adjusts the thrust like F = P/v?

I assert again that this kind of thinking requires a preferred frame, and thus violates SR.

Or you could also give the example of EM Drive ship 1 (which started from a different place) being overtaken by EM Drive ship 2 ...

EDIT:

See White and Joosten, Appendix :

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20140013174.pdf
« Last Edit: 05/07/2015 12:17 AM by Rodal »

Offline deltaMass

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LOL. I am not sure whether you're agreeing with me or not, but ship #2 is going to do that anyway  8)

There are people in various comment threads citing Langmuir's definitions of pathological science, and specifically that as time goes on, the effect becomes smaller and smaller. But this is not the case here; indeed, since Mr. March has gained some extra control of the phasing profile, they are now north of 100 uN and breaking their own records.

So it's never a good time to launch a starship? - stuff and nonsense!

Offline Rodal

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EM Drive ships seem to  "know" what to do and when to do it in order not to produce a paradox:


Quote from: Joosten and White
This condition occurs at a change in time of  which equates to a. When this
situation occurs, in order to ensure that the input energy is
equal to the change in kinetic energy, the thrust to power
performance will have to decrease over time
. This scenario
has an analog in the terrestrial realm when considering
a turbine aircraft flight profile. At takeoff, the turbine
aircraft has a very high thrust to power (hundreds of
N/kW), but at cruise altitude, the thrust to power performance
is much lower (1-10 N/kW). The following graph
shows the curve with some highlighted data points for
consideration.

I don't understand this.  Is there an entropy-like emergent 2nd law that prevents the paradox from occurring?
(Just like it is extremely improbable for an egg smashed on the floor to spontaneously reconstitute itself)

Or something like Hawking's law to prevent time-travel-to-the-past paradoxes? https://en.wikipedia.org/wiki/Chronology_protection_conjecture

How about the scenario proposed by @frobnicat of using the EM Drives as generators? and create a paradox on top of a paradox?

http://forum.nasaspaceflight.com/index.php?topic=37438.msg1370818#msg1370818
« Last Edit: 05/07/2015 01:08 AM by Rodal »

Offline deltaMass

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I must reject the analysis by J & W in Appendix A, but thanks for the link.

I have already mentioned in my preamble that not only is any propellantless propulsion craft capable of perpetuum mobile operation, but that free energy is available on top of that to boot.

This causes many people to break out in hives, or to resort to chewing their towels.  ::)

We can of course test to see this at work. We use a rotary configuration and when the tangential velocity exceeds 2/k, we switch from external power to a coaxially mounted generator. And then begin charging people for the juice. Outrageous!  8)
« Last Edit: 05/07/2015 12:33 AM by deltaMass »

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