Author Topic: EM Drive Developments - related to space flight applications - Thread 3  (Read 1878110 times)

Offline Rodal

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The difference between the Metal and the Copper model is perfect metal and our model of copper material. The difference between the Copper and zCopper model is the orientation of the dipole antenna. Both (all 3) models are excited by an Ez source. The Copper model antenna is aligned parallel to the y-axis while the zCopper model antenna is aligned parallel to the z-axis. That is it. Performance wise, the zCopper model gave a meep calculated quality factor ~40 times higher than the already high quality factor of the copper model, and over 10 times higher than the Metal model.

If the Poynting vector field is weaker, doesn't this tell us something? I wonder if the Metal model Poynting vector field is intermediate because the Medal model Q was intermediate.

The Metal model and the Copper models give the same Poynting vector field, no difference.

The zCopper model gives a weaker Poynting vector field that both the Copper and Metal models.

1) So it looks like what is important is the orientation of the antenna. It is better to orient the antenna perpendicular (y) to the source current Ez than to align it in the same z direction

QUESTION: Why ?
_________________________________________

2) The material model difference between Copper and Metal makes no difference to the Poynting vector field

« Last Edit: 07/04/2015 03:58 AM by Rodal »

Offline SeeShells

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The difference between the Metal and the Copper model is perfect metal and our model of copper material. The difference between the Copper and zCopper model is the orientation of the dipole antenna. Both (all 3) models are excited by an Ez source. The Copper model antenna is aligned parallel to the y-axis while the zCopper model antenna is aligned parallel to the z-axis. That is it. Performance wise, the zCopper model gave a meep calculated quality factor ~40 times higher than the already high quality factor of the copper model, and over 10 times higher than the Metal model.

If the Poynting vector field is weaker, doesn't this tell us something? I wonder if the Metal model Poynting vector field is intermediate because the Medal model Q was intermediate.

The Metal model and the Copper models give the same Poynting vector field, no difference.

The zCopper model gives a weaker Poynting vector field that both the Copper and Metal models.

1) So it looks like what is important is the orientation of the antenna. It is better to orient the antenna perpendicular (y) to the source current Ez than to align it in the same z direction

QUESTION: Why ?
_________________________________________

2) The material model difference between Copper and Metal makes no difference to the Poynting vector field
Look at the poynting vectors from this dipole, you posted it this morning.
https://en.wikipedia.org/wiki/Poynting_vector#/media/File:DipoleRadiation.gif
Dipole Radiation, Dipole parallel to the z-axis, electric field and poynting-vector in the x-z-plane. Colours indicate the strength of the electric field vector.
« Last Edit: 07/04/2015 04:38 AM by SeeShells »

Offline lmbfan

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Updated and tested warp_shell.ctl is attached.

Offline deltaMass

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You guys tickle me pink. It doesn't matter where you put the antenna if you are using Maxwell/Poynting to figure that out. That theory says that you get zero thrust. You're better off with a Hail Mary. It's logical.

Offline TheTraveller

You guys tickle me pink. It doesn't matter where you put the antenna if you are using Maxwell/Poynting to figure that out. That theory says that you get zero thrust. You're better off with a Hail Mary. It's logical.

Correct.

Antenna design, placement & impedance matching is critical to being able to have a high Q frustum filled with non phase distorted EM energy.

My spreadsheet can assist where to place the antenna so it continually excites a high energy standing wave with a continually variable guide wavelength.

Get it wrong and well there will little or no Force generated.
"As for me, I am tormented with an everlasting itch for things remote. I love to sail forbidden seas.
Herman Melville, Moby Dick

Offline TheTraveller

Traveler - Not attacking, just pointing something out.

In my book, Shawyer gets major points.  Best I can tell, the conical Frustum EM Drive thing is his concept.  He spent a lot of years trying to figure things out, building one experimental model after another.   In some areas, he was clearly ahead of the curve - I used to make comments to this effect in prior versions of this thread.

Lately, though, what I see are grand claims lacking substance - most of them coming from you.  Grand claims, to be taken seriously, REQUIRE grand evidence.  A new theory or model won't suffice here.  To back these claims up, to have them taken seriously, Shawyer will need to cough up a truly impressive EM Demo model - one that can be replicated by others. Talking about something that can lift itself, or dang close to it.

At this point, your relentless promotions are hurting Shawyer's case far more than you are helping it.

Shawyer is in business to make money from his IP. Can't see him providing DIY kits.

Building a total system that generates 9.8N/ kg of total mass is not easy. Way beyong DIY.

Any statements I make are based on data, images & documents in my files that I recently shared.

I have showed how Shawyers use of Cullen's equation 15 is valid and those that claim otherwise don't understand what guide wavelength is and that it will not vary if you turn a 1 end closed waveguide into a 2 end closed waveguide.

In the near future I will go through each of the 16 equations and 4 diagrams in the Shawyer Theory paper, invite comments, put the negative comments to Shawyer and post back his comments.

You see it is easy to say Shawyers theory is wrong but maybe not so easy to go equation by equation through the theory paper and make such claims when Shawyer will respong.

So let's see how willing those who attach Shawyer when he is not here to defend his theory will be to have to defend their claims when Shawyer will defend them.

If I was a betting man, I would bet the critics don't score one goal.
« Last Edit: 07/04/2015 12:12 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 SeeShells

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Traveler - Not attacking, just pointing something out.

In my book, Shawyer gets major points.  Best I can tell, the conical Frustum EM Drive thing is his concept.  He spent a lot of years trying to figure things out, building one experimental model after another.   In some areas, he was clearly ahead of the curve - I used to make comments to this effect in prior versions of this thread.

Lately, though, what I see are grand claims lacking substance - most of them coming from you.  Grand claims, to be taken seriously, REQUIRE grand evidence.  A new theory or model won't suffice here.  To back these claims up, to have them taken seriously, Shawyer will need to cough up a truly impressive EM Demo model - one that can be replicated by others. Talking about something that can lift itself, or dang close to it.

At this point, your relentless promotions are hurting Shawyer's case far more than you are helping it.

Shawyer is in business to make money from his IP. Can't see him providing DIY kits.

Building a total system that generates 9.8N/ kg of total mass is not easy. Way beyong DIY.

Any statements I make are based on data, images & documents in my files that I recently shared.

I have showed how Shawyers use of Cullen's equation 15 is valid and those that claim otherwise don't understand what guide wavelength is and that it will not vary if you turn a 1 end closed waveguide into a 2 end closed waveguide.

In the near future I will go through each of the 16 equations and 4 diagrams in the Shawyer Theory paper, invite comments, put the negative comments to Shawyer and post back his comments.

You see it is easy to say Shawyers theory is wrong but maybe not so easy to go equation by equation through the theory paper and make such claims when Shawyer will respong.

So let's see how willing those who attach Shawyer when he is not here to defend his theory will be to have to defend their claims when Shawyer will defend them.

If I was a betting man, I would bet the critics don't score one goal.
That would be interesting. I try as an researcher and engineer to question everything. Even you and RS's theories as there exists holes in his theories that have been pointed out by people better than me.
I wrote you on the Reddit blog after I read RS's application for a patent and I'll repost here and maybe you'll reply.

QUOTE: Good luck with trying to invalidate Newton's second law by this overly simplistic explanation. On one of my patents invoking the fracture mechanics of a silicon wafer with a wafer carrier I played hell with the reviewers. Fracture mechanics was and still is poorly understood and they beat the crap out of me pushing me to explain what couldn't be explained. It breaks cleanly just didn't do it.

I see SPR having the same issues talking about thrust with this over simplistic explanation. If you are having a tough time convincing some of the more knowledgeable in physics of this working how does SPR think they can convince the reviewers for patents? If you are a friend to RS and a good engineer please tell him it just may not fly because he is seemingly violating one of the most inviolate laws we have and his explanation is severely lacking.
END QUOTE


Offline TheTraveller

Traveler - Not attacking, just pointing something out.

In my book, Shawyer gets major points.  Best I can tell, the conical Frustum EM Drive thing is his concept.  He spent a lot of years trying to figure things out, building one experimental model after another.   In some areas, he was clearly ahead of the curve - I used to make comments to this effect in prior versions of this thread.

Lately, though, what I see are grand claims lacking substance - most of them coming from you.  Grand claims, to be taken seriously, REQUIRE grand evidence.  A new theory or model won't suffice here.  To back these claims up, to have them taken seriously, Shawyer will need to cough up a truly impressive EM Demo model - one that can be replicated by others. Talking about something that can lift itself, or dang close to it.

At this point, your relentless promotions are hurting Shawyer's case far more than you are helping it.

Shawyer is in business to make money from his IP. Can't see him providing DIY kits.

Building a total system that generates 9.8N/ kg of total mass is not easy. Way beyong DIY.

Any statements I make are based on data, images & documents in my files that I recently shared.

I have showed how Shawyers use of Cullen's equation 15 is valid and those that claim otherwise don't understand what guide wavelength is and that it will not vary if you turn a 1 end closed waveguide into a 2 end closed waveguide.

In the near future I will go through each of the 16 equations and 4 diagrams in the Shawyer Theory paper, invite comments, put the negative comments to Shawyer and post back his comments.

You see it is easy to say Shawyers theory is wrong but maybe not so easy to go equation by equation through the theory paper and make such claims when Shawyer will respong.

So let's see how willing those who attach Shawyer when he is not here to defend his theory will be to have to defend their claims when Shawyer will defend them.

If I was a betting man, I would bet the critics don't score one goal.
That would be interesting. I try as an researcher and engineer to question everything. Even you and RS's theories as there exists holes in his theories that have been pointed out by people better than me.
I wrote you on the Reddit blog after I read RS's application for a patent and I'll repost here and maybe you'll reply.

QUOTE: Good luck with trying to invalidate Newton's second law by this overly simplistic explanation. On one of my patents invoking the fracture mechanics of a silicon wafer with a wafer carrier I played hell with the reviewers. Fracture mechanics was and still is poorly understood and they beat the crap out of me pushing me to explain what couldn't be explained. It breaks cleanly just didn't do it.

I see SPR having the same issues talking about thrust with this over simplistic explanation. If you are having a tough time convincing some of the more knowledgeable in physics of this working how does SPR think they can convince the reviewers for patents? If you are a friend to RS and a good engineer please tell him it just may not fly because he is seemingly violating one of the most inviolate laws we have and his explanation is severely lacking.
END QUOTE

I'm online maybe 2 hours a day every 3 days or so. Some of my meds literally take me off line. Very confused dreams. Weird for me as I normally can almost control my dreans.

BTW I have no theory.

Shawyer recently added more to his theory. Read how he believes Force generation is built up, bounce by bounce, as the EMDrive initially accelerates

http://www.emdrive.com/IAC13paper17254.v2.pdf

I really do wish you luck in your build efforts but believe you will be lucky to see anything.

Had a talk with Shawyer and now understand why scales are a very bad way to try to measure Force. I have changed my build to a rotary test rig as that is really the only way to allow Force to develope as the EMDrive, being free to move, starts to accelerate.
"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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You guys tickle me pink. It doesn't matter where you put the antenna if you are using Maxwell/Poynting to figure that out. That theory says that you get zero thrust. You're better off with a Hail Mary. It's logical.

You have overstated your case.  There is nothing in Maxwell's or Poynting's theory saying that one should get zero thrust out of anything.  Actually, Maxwell was the first scientist to derive the equations predicting that electromagnetic radiation can produce stresses, and the stress-energy tensor carries his name to honor that achievement.

Case in point: if there is a net Poynting vector due to energy that gets dissipated into heat asymetrically, there maybe asymmetric heat transfer (by convection and/or radiation)  resulting in asymmetric forces: "thrust".  That is fully consistent with Maxwell's and Poynting's equations as well as consistent with Newton's equations. 

A correct statement you could make is that you, personally, don't see a way that enough thrust/InputPower can result from an asymmetric microwave cavity that is in excess of a perfect photon rocket thrust/inputPower by several orders of magnitude, but that is not the statement you made. 

Quote from: Anson Mount
I'm an enemy of exposition. I feel there's no need to overstate.
 

« Last Edit: 07/04/2015 02:39 PM by Rodal »

Offline SeeShells

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That would be interesting. I try as an researcher and engineer to question everything. Even you and RS's theories as there exists holes in his theories that have been pointed out by people better than me.
I wrote you on the Reddit blog after I read RS's application for a patent and I'll repost here and maybe you'll reply.

QUOTE: Good luck with trying to invalidate Newton's second law by this overly simplistic explanation. On one of my patents invoking the fracture mechanics of a silicon wafer with a wafer carrier I played hell with the reviewers. Fracture mechanics was and still is poorly understood and they beat the crap out of me pushing me to explain what couldn't be explained. It breaks cleanly just didn't do it.

I see SPR having the same issues talking about thrust with this over simplistic explanation. If you are having a tough time convincing some of the more knowledgeable in physics of this working how does SPR think they can convince the reviewers for patents? If you are a friend to RS and a good engineer please tell him it just may not fly because he is seemingly violating one of the most inviolate laws we have and his explanation is severely lacking.
END QUOTE

I'm online maybe 2 hours a day every 3 days or so. Some of my meds literally take me off line. Very confused dreams. Weird for me as I normally can almost control my dreans.

BTW I have no theory.

Shawyer recently added more to his theory. Read how he believes Force generation is built up, bounce by bounce, as the EMDrive initially accelerates

http://www.emdrive.com/IAC13paper17254.v2.pdf

I really do wish you luck in your build efforts but believe you will be lucky to see anything.

Had a talk with Shawyer and now understand why scales are a very bad way to try to measure Force. I have changed my build to a rotary test rig as that is really the only way to allow Force to develope as the EMDrive, being free to move, starts to accelerate.
Sorry about the weird effects of your drugs. I have a dear friend right now who is going through untreatable pancreatic cancer and he is at a stage 3 doing heavy drugs. It's just horrible, but one thing you are is head strong and a heck of a fighter. That's obvious and that is really the best meds to have.

I re-read RS's patent app and sorry he is still going to get heat, it's the way it's going to be.

You know i decided to not go with yours and RS's cavity profiles but with the Yang profile, and you know it doesn't have as high of Q but the N/Kw ratio is higher, that says something.

As to my cavity design not working, we shall see. Nobody has all the right answers.
I would like to do a overview of why I believe I needed some flexibility from the primary design.


Reddit quote... to you.
The primary design is a copy cat and this copy cat design is what I'll be testing first to gather my baseline data.
Once i have that basic data I need to gain data from other options that may or may not change the operational characteristics of the EMDrive.
I wanted to change one parameter very quickly without designing and building a whole new Frustum. You and others are or have built basic designs that are inviolate and very inflexible. If you do build a new one that new Frustum can introduce more variables in the data.
Design factors that influenced me and are known issues are.
Heat warpage of the solid copper walls changing Q.
Hot air in the frustum causing unwanted buoyancy and a possible misreading of thrust.
Antenna placement and type.
Small reflector plate distance from the large end plate.
Simply being able to see if any plasma discharges were visible within the cavity.
Trying to keep the basic form intact while allowing flexibility during later tests I opted to.
Used a perforated Copper Frustum, letting the hot air out and keeping the walls from buckling under the 800+ watts of Magnetron input and changing Q.
Split cavity. Allows me to be able to open the Frustum and change antennas and position of the antennas, as nobody has really looked at that as a big contributor to thrust.
Also the split design allows me to pull out the small end plate and replace it to do either TM or TE modes for testing.
The basic frustum still maintains the primary design except the perforated Copper walls for cooling but allows me to keep one basic design while being able to only change one item and to log the data.
Make sense? I understand your concern and I hope I kept the copy cat design by only changing the cooling by a perforated copper case.   
Quote again....to you questioning my design.
Thanks for your input, I do value it.
I've just fried my brain on reading a great paper from MIT even considering my math skills felt like pidgin math. :) after. Good paper and I highly recommend it. http://web.mit.edu/22.09/ClassHandouts/Charged%20Particle%20Accel/CHAP12.PDF
I've read Rodger Shawyer's paper and while I believe there is much to discuss on the reasons why he has seen thrust. I don't dispute the need for building a stable Q and exciting and maintaining the desired Mode for the cavity. Also there maybe some questions of Q considering Yang's high thrust with lower Q factor.
While I think it's import to have a cavity that is to exact dimensions. I feel the variation of the length by less than 1/2 the thickness of a piece of paper controlling a high Q factor (.05mm) will be subject to the thermal expansion coefficient of the copper Frustum with even a minor temperature increase (tec of Copper 16.6 wiki source) it will deviate enough to change Q.
The question to me is not so much trying to control the dimensionality, but the frequency as well.
I chose a Magnetron because of it's wide spectral transmission centered around 2.45 Ghz and being forgiving in delivering power into a variable expanding and contracting cavity. Not a perfect solution but it should work to give me some base data.
I have a heavy structural heat fin design design in the works for the endplate (similar to the CPU cooling systems you see) that can be coupled to the other endplate using Stainless threaded rod, but only after I've verified with my design the cavity dimensions, mode selections and power factor.
I originally wanted to do a stepper motor feedback and control to adjust the cavity length on the fly using a small loop wire in the cavity. I don't believe it's going to be responsive enough. So eventually I'll be controlling the frequency of the magnetron with a feedback loop by monitoring the Q within the cavity.
I would recommend reading the MIT paper because it covers the steps needed for maintaining high Q in particle accelerators. Hey while your SO has you strapped down in the bed resting, it's a good read.
End Quotes

Rotary designs have been discussed here and RS's air bearing and how it could lead to actions just like we see him expound on (sorry a red flag for me) in a push it a little and watch it go. So kiddo get better and BUILD your drive I suspect you'l not see it turn into a high speed Merry Go Around.

Online WarpTech

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You guys tickle me pink. It doesn't matter where you put the antenna if you are using Maxwell/Poynting to figure that out. That theory says that you get zero thrust. You're better off with a Hail Mary. It's logical.

You need to look at the equation I posted yesterday. I shows there is a huge thrust, many orders larger than a photon rocket, going like 1/r^2 from the apex of the cone.

http://forum.nasaspaceflight.com/index.php?topic=37642.msg1399882#msg1399882

Todd

Offline Rodal

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You guys tickle me pink. It doesn't matter where you put the antenna if you are using Maxwell/Poynting to figure that out. That theory says that you get zero thrust. You're better off with a Hail Mary. It's logical.

You need to look at the equation I posted yesterday. I shows there is a huge thrust, many orders larger than a photon rocket, going like 1/r^2 from the apex of the cone.

http://forum.nasaspaceflight.com/index.php?topic=37642.msg1399882#msg1399882

Todd

Need further exposition to understand your message.  For example, when you state:

Quote from: WarpTech
for a tapered rectangular waveguide of width and height;

x*A*tanθ and x*B*tanθ

x is previously defined as the longitudinal coordinate.  Is x a dimensional coordinate or a dimensionless coordinate?

What is θ ? Is that the cone half-angle measured from the axisymmetry longitudinal axis x?

Do A and B have dimensions?

In that case, and if x has dimensions, did you mean

a tapered rectangular waveguide of width and height;

A*tanθ and B*tanθ

as xA would otherwise have the dimensions of an area.

_______________

When you state

Quote
thrust... , going like 1/r^2 from the apex of the cone.

does that mean that the truncated cones should terminate near the apex of the cone, and that therefore they are presently grossly underdesigned, since they terminate way before the apex of the cone?
« Last Edit: 07/04/2015 03:35 PM by Rodal »

Offline deuteragenie

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Dr. Rodal- Time slices 3 thru 7 have been added to the csv folder on Google Drive. Same place as the other ones, I just changed the name to reflect 3 thru 13.
@aero:

two important questions to investigate this further:

1) How do you impose boundary conditions? What are your boundary conditions and how do you actually implement them in Meep (I read that boundary conditions can be imposed such that the problem becomes nonlinear, which would also partly explain the results)

2) TS013 : does this mean that you only marched the FD solution through 13 time steps total?  If so, this is way insufficient to make sure that this is not just a transient, if so we would need to investigate marching forwards many more time steps to investigate the time evolution

It appears from what we're seeing in the gif movies and what I've calculated for a tapered waveguide, that the two match. For a very long frustum waveguide, starting at the small end with a k vector perpendicular to the x-axis, the axis of the frustum;

k2 = 0 + ky2 + kz2, initially.

This is the rocket equation (per photon);

dpx = (E(w)/(c2*px))*[dE(w) + (c/p)*hbar2*(Xmn2/x^3)*dx]

Xmn2 = [(m*pi/A*tanθ)2 + (n*pi/B*tanθ)2], for a tapered rectangular waveguide of width and height;

x*A*tanθ and x*B*tanθ


Multiple reflections from the side wall will rotate k into kx, thereby transferring all of the momentum that was perpendicular to the axis, to be parallel to the axis. That rotation occurs a little bit, each time it reflects from the side walls. You can see this clearly in the Hx-z images from @aero's work. (Thank you @aero and @VAXheadroom) This is WHY a smaller cone angle and a longer frustum is better. "If it were long enough", there would be so many bounces that no energy would reach the big end, it would all be converted into thrust.

I retract my previous statement that I've given up on the microwaves, thanks to all the work done here. Theory and simulation seem to be merging. :)
Todd

If I understand your explanation correctly, there should not be a need for the big end to be closed.  Furthermore, linear sides may also not be optimal.  An (inverse) hyperbolic shape would give better results.

Would something like this be optimal according to your theory?
http://www.mathworks.com/matlabcentral/fileexchange/screenshots/4304/original.jpg

Or is it so that the number of bounces need to be maximized and two almost parallel lines going to infinity would be optimal? I can hardly imagine this would be the case, but just to understand...
« Last Edit: 07/04/2015 03:49 PM by deuteragenie »

Offline Rodal

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...
I've just fried my brain on reading a great paper from MIT even considering my math skills felt like pidgin math. :) after. Good paper and I highly recommend it. http://web.mit.edu/22.09/ClassHandouts/Charged%20Particle%20Accel/CHAP12.PDF...
Those are the class notes chapter 12 of MIT's Course in the Nuclear Engineering Department (Dept. 22),  Principles of Nuclear Radiation Measurement and Protection, Undergraduate Course 22.09

The following chapters (not as easy to find)  may also be of interest:

Chapter 13  Phase Dynamics

https://stuff.mit.edu/afs/athena/course/22/22.09/ClassHandouts/Charged%20Particle%20Accel/CHAP13.PDF

and

Chapter 14 Radio-Frequency Linear Accelerators

https://stuff.mit.edu/afs/athena/course/22/22.09/ClassHandouts/Charged%20Particle%20Accel/CHAP14.PDF



« Last Edit: 07/04/2015 03:55 PM by Rodal »

Offline wallofwolfstreet

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You guys tickle me pink. It doesn't matter where you put the antenna if you are using Maxwell/Poynting to figure that out. That theory says that you get zero thrust. You're better off with a Hail Mary. It's logical.

You have overstated your case.  There is nothing in Maxwell's or Poynting's theory saying that one should get zero thrust out of anything.  Actually, Maxwell was the first scientist to derive the equations predicting that electromagnetic radiation can produce stresses, and the stress-energy tensor carries his name to honor that achievement.

Case in point: if there is a net Poynting vector due to energy that gets dissipated into heat asymetrically, there maybe asymmetric heat transfer (by convection and/or radiation)  resulting in asymmetric forces: "thrust".  That is fully consistent with Maxwell's and Poynting's equations as well as consistent with Newton's equations. 

A correct statement you could make is that you, personally, don't see a way that enough thrust/InputPower can result from an asymmetric microwave cavity that is in excess of a perfect photon rocket thrust/inputPower by several orders of magnitude, but that is not the statement you made. 

Quote from: Anson Mount
I'm an enemy of exposition. I feel there's no need to overstate.
 

While saying "Maxwell predicts zero thrust" is an overstatement, I have to agree with deltamass here.  I will also throw my hat into the ring by saying I don't personally see a way "that thrust/InputPower can result from an asymmetric microwave cavity that is in excess of a perfect photon rocket thrust/inputPower by several orders of magnitude", but I'm going to add something else:  I personally see no way that any physics simulation software, FEM, FDM, BEM, or anything else, will show any meaningful thrust on the device.

And in fact, it's worse that that.  If you did see thrust with meep, what is more likely:

1) It has accurately predicted emdrive thrust from traditional physics.

2) The simulation was wrong.   

I've done plenty of work with numerical methods and written enough FDM codes myself to know that you don't always get exactly what you expect.  That's the nature of approximation, especially understanding how error can propagate from grid point to grid point or element to element.

Maybe I have this wrong, but I've gotten the impression that some people feel that all this confusion can be solved with MEEP.  If MEEP showed use something that we didn't already know, ie. a net thrust greater than a photon rocket, I wouldn't consider that a plus for the EMdrive.  I would consider it a negative for MEEP.     

Online WarpTech

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You guys tickle me pink. It doesn't matter where you put the antenna if you are using Maxwell/Poynting to figure that out. That theory says that you get zero thrust. You're better off with a Hail Mary. It's logical.

You need to look at the equation I posted yesterday. I shows there is a huge thrust, many orders larger than a photon rocket, going like 1/r^2 from the apex of the cone.

http://forum.nasaspaceflight.com/index.php?topic=37642.msg1399882#msg1399882

Todd

Need further exposition to understand your message.  For example, when you state:

Quote from: WarpTech
for a tapered rectangular waveguide of width and height;

x*A*tanθ and x*B*tanθ

x is previously defined as the longitudinal coordinate.  Is x a dimensional coordinate or a dimensionless coordinate?

What is θ ? Is that the cone half-angle measured from the axisymmetry longitudinal axis x?

Yes, x is the longitudinal coordinate with units of "meters". I sometimes interchange x and z, I prefer z but since @aero called it x, I'm trying to be consistent with the group.

Yes, θ is the half-angle, just as it's always been.

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Do A and B have dimensions?

No, they are dimensionless. I threw those in there at the last minute. My actual equation is just square, it could be a circle, it could be a rectangle. It doesn't make a difference, just easier to solve. A & B were to imply it could be a rectangle as a multiple of "x" in meters. The point is to pull the x dependence out of the wall dimension or diameter, to parameterize the wall dimension in terms of x.

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In that case, and if x has dimensions, did you mean

a tapered rectangular waveguide of width and height;

A*tanθ and B*tanθ

as xA would otherwise have the dimensions of an area.

No, it is length, in meters. Better said A(x)tanθ, then I pulled out the x dependence.

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_______________

When you state

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thrust... , going like 1/r^2 from the apex of the cone.

does that mean that the truncated cones should terminate near the apex of the cone, and that therefore they are presently grossly underdesigned, since they terminate way before the apex of the cone?

My thoughts are presently that the cone should look more like a trombone horn. It should have a very small angle near the antenna so as to setup a standing wave very near the cut-off that propagates very slowly and accelerates as it moves toward the big end. The small end, being nearly a cylinder, allows energy to build up before it accelerates too far, too fast. The power depends on the group velocity, not c, which is nearly zero in the x direction when the force is at it's maximum.

There is a natural acceleration for the Xmm modes in a cone toward the big end. The stored energy and resonant frequency depend on the diameter. As the diameter gets larger the frequency gets lower and this is a gradient in the potential "stored" energy.

Just like Newtonian gravity. There is a force acting on the resonant energy toward the big end that goes like 1/r^2 from the apex. So if you could have a much higher starting frequency you would want to extend the cone to a smaller diameter and a much slower taper.

The k vectors look a lot like this...


Todd

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Dr. Rodal- Time slices 3 thru 7 have been added to the csv folder on Google Drive. Same place as the other ones, I just changed the name to reflect 3 thru 13.
@aero:

two important questions to investigate this further:

1) How do you impose boundary conditions? What are your boundary conditions and how do you actually implement them in Meep (I read that boundary conditions can be imposed such that the problem becomes nonlinear, which would also partly explain the results)

2) TS013 : does this mean that you only marched the FD solution through 13 time steps total?  If so, this is way insufficient to make sure that this is not just a transient, if so we would need to investigate marching forwards many more time steps to investigate the time evolution

It appears from what we're seeing in the gif movies and what I've calculated for a tapered waveguide, that the two match. For a very long frustum waveguide, starting at the small end with a k vector perpendicular to the x-axis, the axis of the frustum;

k2 = 0 + ky2 + kz2, initially.

This is the rocket equation (per photon);

dpx = (E(w)/(c2*px))*[dE(w) + (c/p)*hbar2*(Xmn2/x^3)*dx]

Xmn2 = [(m*pi/A*tanθ)2 + (n*pi/B*tanθ)2], for a tapered rectangular waveguide of width and height;

x*A*tanθ and x*B*tanθ


Multiple reflections from the side wall will rotate k into kx, thereby transferring all of the momentum that was perpendicular to the axis, to be parallel to the axis. That rotation occurs a little bit, each time it reflects from the side walls. You can see this clearly in the Hx-z images from @aero's work. (Thank you @aero and @VAXheadroom) This is WHY a smaller cone angle and a longer frustum is better. "If it were long enough", there would be so many bounces that no energy would reach the big end, it would all be converted into thrust.

I retract my previous statement that I've given up on the microwaves, thanks to all the work done here. Theory and simulation seem to be merging. :)
Todd

If I understand your explanation correctly, there should not be a need for the big end to be closed.  Furthermore, linear sides may also not be optimal.  An (inverse) hyperbolic shape would give better results.

Would something like this be optimal according to your theory?
http://www.mathworks.com/matlabcentral/fileexchange/screenshots/4304/original.jpg

Or is it so that the number of bounces need to be maximized and two almost parallel lines going to infinity would be optimal? I can hardly imagine this would be the case, but just to understand...

Extend the small end to nearly a cylinder, like a Trombone. I can't say it is "optimal", because I haven't optimized any equations yet. But given the equations I have, that's what I am thinking. Energy striking the big end causes it to lose thrust, but gain stored energy. IMO, resonance is just stored energy. It doesn't generate any thrust. It would be better to leave the big end open and pump in higher power. You want Xmn mode resonance, not p mode resonance.
Todd

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The k vectors look a lot like this...


Todd

Thanks for taking the time to explain this.  With the ends closed (as claimed by Shawyer) how can anything get out to result in acceleration of the closed truncated cone without violating conservation of momentum? (if so what gets out and how does it get out?).  If nothing gets out, it appears that acceleration of the copper cone would imply a violation of CoM.

Or are you considering that the use of choke joints (  https://en.wikipedia.org/wiki/Waveguide_flange#Choke_connection  ) (hat tip R. L. for the references) may allow emission out of the frustum thus preserving conservation of momentum?
« Last Edit: 07/04/2015 04:31 PM by Rodal »

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I've just fried my brain on reading a great paper from MIT even considering my math skills felt like pidgin math. :) after. Good paper and I highly recommend it. http://web.mit.edu/22.09/ClassHandouts/Charged%20Particle%20Accel/CHAP12.PDF...
Those are the class notes chapter 12 of MIT's Course in the Nuclear Engineering Department (Dept. 22),  Principles of Nuclear Radiation Measurement and Protection, Undergraduate Course 22.09

The following chapters (not as easy to find)  may also be of interest:

Chapter 13  Phase Dynamics

https://stuff.mit.edu/afs/athena/course/22/22.09/ClassHandouts/Charged%20Particle%20Accel/CHAP13.PDF

and

Chapter 14 Radio-Frequency Linear Accelerators

https://stuff.mit.edu/afs/athena/course/22/22.09/ClassHandouts/Charged%20Particle%20Accel/CHAP14.PDF

Thank you Jose!
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The k vectors look a lot like this...


Todd

Thanks for taking the time to explain this.  With the ends closed (as claimed by Shawyer) how can anything get out to result in acceleration of the closed truncated cone without violating conservation of momentum? (if so what gets out and how does it get out?).  If nothing gets out, it appears that acceleration of the copper cone would imply a violation of CoM.

Or are you considering that the use of choke joints (  https://en.wikipedia.org/wiki/Waveguide_flange#Choke_connection  ) (hat tip R. L. for the references) may allow emission out of the frustum thus preserving conservation of momentum?
It has been a worry of mine where the two halves meet. Ref: http://www.westernrubber.com/products/wesshield-emi-shielding/

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