Author Topic: EM Drive Developments - related to space flight applications - Thread 2  (Read 2106308 times)

Offline Flyby

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huh... :o was going to start on it today after getting the feedback, but it seems Lasoi has beaten me to it while i was sleeping...
but I'll have a look at it myself anyway...

Thanks for all those replying that it was NOT the Chinese test engine. It kinda confirmed my suspicions that something wasn't right...

The problem with most of the drawings i see about the resonance cavities is that they are most likely drawings of concepts, they come in all shapes and angles but none give me the impression to be actual engineering based drawings.
I do not think it is wise attempting to extract any realworld info from conceptual drawings.

fe, There is a clear visual difference between the superconductivity cavity drawing from Shawyer (see higher up) and fe, the Chinese drawings. Shawyer's drawing is clearly based on an engineering drawing, where the Chinese drawing is way more schematically build. I'd be much more confident in basing assumptions on Shawyer's drawing then on the Chinese one...
My gut feeling (i know, hardly a scientific approach) says that the chinese drawing has little to no correlation to the real testunit they've build.

Offline Flyby

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The Finite Element and the Finite Difference calculations of NASA's EM Drive confirm that the electromagnetic fields are spherical standing waves away from the flat ends.

For a given spherical radius, the bigger the cone's angle, the more different is the spherical surface from a flat end, and the more important is to have spherical ends.  Kudos to Shawyer for being the first EM Drive researcher to realize this.


Got it! It is all about having equal distances for the bouncing waves between the 2 top/bottom surfaces. Basically, it is a truncated spherical cone...
http://mathworld.wolfram.com/SphericalCone.html

thnx for the clarification...

Offline Rodal

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....
My gut feeling (i know, hardly a scientific approach) says that the chinese drawing has little to no correlation to the real testunit they've build.
What Chinese drawing are you referring to? Could you please give a link or a reference to it?  Thanks

Offline Rodal

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The Finite Element and the Finite Difference calculations of NASA's EM Drive confirm that the electromagnetic fields are spherical standing waves away from the flat ends.

For a given spherical radius, the bigger the cone's angle, the more different is the spherical surface from a flat end, and the more important is to have spherical ends.  Kudos to Shawyer for being the first EM Drive researcher to realize this.


Got it! It is all about having equal distances for the bouncing waves between the 2 top/bottom surfaces. Basically, it is a truncated spherical cone...
http://mathworld.wolfram.com/SphericalCone.html

thnx for the clarification...

The correct shape to have perfect propagation of electromagnetic waves (respecting all Boundary Conditions) is a spherical cone truncated at its narrow end by another section of a sphere. 

<< It is all about having equal spherical radial distances for the standing spherical waves between the 2 top/bottom surfaces>>

Yes, that should be called a "truncated spherical cone".  Thanks for the  http://mathworld.wolfram.com/SphericalCone.html  reference.

The truncated cone with flat ends previously used by Shawyer (before its present superconducting design) and by NASA Eagleworks and Juan Yang in China do not satisfy the ideal shape for the truncated ends which should be spherical. 

For a given spherical radius, the larger the cone angle, the more important is this difference.
« Last Edit: 02/21/2015 01:24 PM by Rodal »

Offline Notsosureofit

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http://eec.wustl.edu/aboutthedepartment/Pages/news-story.aspx?news=7577&source=admin

http://adsabs.harvard.edu/abs/2014NatPh..10..394P

http://ieeexplore.ieee.org/iel7/4563994/4814557/06690216.pdf

Man we need way stronger magnetic fields and better materials in that thing. The more I keep reading about this subject of PT symmetry breaking the clearer it becomes that this is routine.

To my mind, the most interesting aspect of these papers is the incorporation of non-linear materials generating additional frequency components.

Offline Rodal

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http://eec.wustl.edu/aboutthedepartment/Pages/news-story.aspx?news=7577&source=admin

http://adsabs.harvard.edu/abs/2014NatPh..10..394P

http://ieeexplore.ieee.org/iel7/4563994/4814557/06690216.pdf

Man we need way stronger magnetic fields and better materials in that thing. The more I keep reading about this subject of PT symmetry breaking the clearer it becomes that this is routine.

To my mind, the most interesting aspect of these papers is the incorporation of non-linear materials generating additional frequency components.

Agreed.  From the point of view of solving the dispersion problem, the nonlinearity of the materials involved is what makes a difference, at least at first sight ?.
« Last Edit: 02/21/2015 12:47 PM by Rodal »

Offline flux_capacitor

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....
My gut feeling (i know, hardly a scientific approach) says that the chinese drawing has little to no correlation to the real testunit they've build.
What Chinese drawing are you referring to? Could you please give a link or a reference to it?  Thanks

I think Flyby refers to the fact that the various EmDrive drawings from the Chinese do not look alike each others. See for example the compilation attached. The two last drawings, largely different, even come from the same 2015 paper. All we can say looking at those pictures is the length of their cavity is perhaps shorter than Shawyer's or Eagleworks designs. But the angles and proportions are all different.
« Last Edit: 02/21/2015 01:04 PM by flux_capacitor »

Offline Notsosureofit

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http://eec.wustl.edu/aboutthedepartment/Pages/news-story.aspx?news=7577&source=admin

http://adsabs.harvard.edu/abs/2014NatPh..10..394P

http://ieeexplore.ieee.org/iel7/4563994/4814557/06690216.pdf

Man we need way stronger magnetic fields and better materials in that thing. The more I keep reading about this subject of PT symmetry breaking the clearer it becomes that this is routine.


To my mind, the most interesting aspect of these papers is the incorporation of non-linear materials generating additional frequency components.

Agreed.  From the point of view of solving the dispersion problem, the nonlinearity of the materials involved is what makes a difference, at least at first sight ?.

As a starting ferinstance, how much native copper oxide is present on the inner surfaces of the cavity ?  Enough to convert 10-7 ?

Offline Rodal

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....
My gut feeling (i know, hardly a scientific approach) says that the chinese drawing has little to no correlation to the real testunit they've build.
What Chinese drawing are you referring to? Could you please give a link or a reference to it?  Thanks

"the Chinese (drawings) do not look alike each others"
Yes, because drawings that do not look like each other in that compilation refer to different EM Drive designs, as explained in the Chinese text of the different published articles by Juan Yang's team.  The fact that Juan Yang has improved on her design and has tested different EM Drive designs does not necessarily mean that there is "little to no correlation to the real test unit they've build".  She documents a large number of tests (much more numerous than the tests conducted at NASA Eagleworks, for example).

Shawyer has also conducted experimental tests with different EM Drive geometries: the "Demo", the "Flight Thruster", the "Experimental", etc., and now the "Superconducting 2014 design".

Similarly, NASA Eagleworks has tested recently the Cannae pillbox design and the truncated cone frustum design and reports experiments for both (drastically different geometries) in the same report "Anomalous..." by Brady et.al.. 

It does not necessarily follow from that that there is "little to no correlation to the real test unit they've build" all it may mean is that they built and tested different geometries.  Unless somebody has some reported information that I have missed, in which case I'll be happy to be better informed.
« Last Edit: 02/21/2015 01:27 PM by Rodal »

Offline Rodal

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http://eec.wustl.edu/aboutthedepartment/Pages/news-story.aspx?news=7577&source=admin

http://adsabs.harvard.edu/abs/2014NatPh..10..394P

http://ieeexplore.ieee.org/iel7/4563994/4814557/06690216.pdf

Man we need way stronger magnetic fields and better materials in that thing. The more I keep reading about this subject of PT symmetry breaking the clearer it becomes that this is routine.


To my mind, the most interesting aspect of these papers is the incorporation of non-linear materials generating additional frequency components.

Agreed.  From the point of view of solving the dispersion problem, the nonlinearity of the materials involved is what makes a difference, at least at first sight ?.

As a starting ferinstance, how much native copper oxide is present on the inner surfaces of the cavity ?  Enough to convert 10-7 ?

Excellent question. 

Offline Notsosureofit

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http://eec.wustl.edu/aboutthedepartment/Pages/news-story.aspx?news=7577&source=admin

http://adsabs.harvard.edu/abs/2014NatPh..10..394P

http://ieeexplore.ieee.org/iel7/4563994/4814557/06690216.pdf

Man we need way stronger magnetic fields and better materials in that thing. The more I keep reading about this subject of PT symmetry breaking the clearer it becomes that this is routine.


To my mind, the most interesting aspect of these papers is the incorporation of non-linear materials generating additional frequency components.

Agreed.  From the point of view of solving the dispersion problem, the nonlinearity of the materials involved is what makes a difference, at least at first sight ?.

As a starting ferinstance, how much native copper oxide is present on the inner surfaces of the cavity ?  Enough to convert 10-7 ?

Excellent question.

While the formula I've been using is based on satisfying General Relativity, it does not tell us anything about the mechanism of momentum conservation.. PT asymmetry, as Mulletron mentions, is a viable candidate, and nonlinear frequency effects could (in theory) satisfy the requirement.


« Last Edit: 02/21/2015 01:38 PM by Notsosureofit »

Offline Rodal

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....
While the formula I've been using is based on satisfying General Relativity, it does not tell us anything about the mechanism of momentum conservation.. PT asymmetry, as Mulletron mentions, is a viable candidate, and nonlinear frequency effects could (in theory) satisfy the requirement.
Can anybody present quantitative experimentally-measured data showing significant PT asymmetry or nonlinear frequency effects for a bulk High Density Polyethylene (purchased commercially from McMaster Carr, if my memory serves me correctly ?) used as the dielectric by NASA Eagleworks in their tests ?

That could be a Rosetta Stone...
« Last Edit: 02/21/2015 03:10 PM by Rodal »

Offline Notsosureofit

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A good question might be how "pristine" the inner surface of a Shawyer cavity might be compared to a NASA one.  NASA is quite used to super-clean surfaces....( their chambers compared to mine ferinstance.....Gulp !!!)

Offline Rodal

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The photo is a bit blurry and that makes estimating a bit challenging, and there are lens distortions to the photo, but nothing too major.  If the concrete block happened to be the standard width of 440 mm, cited by wikipedia, then the dimensions would be roughly as estimated in the chart.

I'm an artist, not a physicist.  If these dimensions seem wrong and you have a different guess for the width of the concrete block, let me know and I'll recalculate based on your width standard.
Thanks to @lasoi, from these dimensions for Shawyer's Flight Thruster (a 3.85GHz thruster weighing 2.92 Kg), we can calculate the most important parameter: the cone's half angle thetaw (as per image below), which is, trivially, a function of the flat base diameters and the axial length:

thetaw=ArcTan[(BigDiameter-SmallDiameter)/(2*AxialLength)],

and add it to my table below (note the cone's half-angle, as a dimensionless quantity, is robust insensitive to the length magnitude of the cinder blocks in the wall on the background of the picture):

For reference. the tangent of the cone's half angle thetaw and the cone's half angle thetaw, in ascending order, for the following cases are:

(Notice how Shawyer progressively increased the cone's half-angle, with time, in his experimental designs, by a factor of 7 in the tangent of the half-angle)

Example (and geometry)                    { Tan[thetaw],thetaw (degrees) }

Shawyer Experimental                        {0.104019,   5.93851}
Shawyer Fligth Thruster                      {0.19086,   10.8055}
Shawyer Demo                                   {0.219054, 12.3557}
NASA Eagleworks frustum                   {0.263889, 14.7827}
Egan's example                                  {0.36397 ,  20}
Prof. Juan Yang  (2014)                      {0.4538,     24.4 }
Shawyer Superconducting 2014          {0.7002,     35}





« Last Edit: 02/21/2015 02:44 PM by Rodal »

Offline Notsosureofit

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There are a lot of references to nonlinear effects in polyethylene, but most seem to be due to impurities of one sort or another.

Offline Rodal

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There are a lot of references to nonlinear effects in polyethylene, but most seem to be due to impurities of one sort or another.
If so, nonlinearity of the HD PE used for the dielectric in the NASA Eagleworks tests, rather than occurring by intelligent design, by intentional doping, would be by accidental impurity, due to lax quality control in the manufacture of the industrially supplied bulk HD PE used by NASA Eagleworks.

EDIT: Still, what types and how much impurity would be necessary to take place in order to have significant nonlinear effects?
« Last Edit: 02/21/2015 03:48 PM by Rodal »

Offline Notsosureofit

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There are a lot of references to nonlinear effects in polyethylene, but most seem to be due to impurities of one sort or another.
So nonlinearity of the HD PE, rather than being by intelligent design, would be by accidental impurity, due to lax quality control in the manufacture of the industrially supplied bulk HD PE used by NASA Eagleworks.

That's a possibility.  Could also explain the difference between some chambers w/ and w/o dielectric ???

Offline Rodal

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There are a lot of references to nonlinear effects in polyethylene, but most seem to be due to impurities of one sort or another.
So nonlinearity of the HD PE, rather than being by intelligent design, would be by accidental impurity, due to lax quality control in the manufacture of the industrially supplied bulk HD PE used by NASA Eagleworks.

That's a possibility.  Could also explain the difference between some chambers w/ and w/o dielectric ???

Still, what types and how much impurity would be necessary to take place in order to have significant nonlinear effects?

Offline Notsosureofit

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There are a lot of references to nonlinear effects in polyethylene, but most seem to be due to impurities of one sort or another.
So nonlinearity of the HD PE, rather than being by intelligent design, would be by accidental impurity, due to lax quality control in the manufacture of the industrially supplied bulk HD PE used by NASA Eagleworks.

That's a possibility.  Could also explain the difference between some chambers w/ and w/o dielectric ???

Still, what types and how much impurity would be necessary to take place in order to have significant nonlinear effects?

Good question.  One of the papers Mulletron brought up:

http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=6690216

has interesting curves showing the frequency shifts.   Maybe Mulletron has a PT input on this point ?

" More interestingly, at the PT phase transition point, also called spontaneous PT phase breaking point, a unidirectional invisible medium was realized"
« Last Edit: 02/21/2015 04:13 PM by Notsosureofit »

Offline Star-Drive

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There are a lot of references to nonlinear effects in polyethylene, but most seem to be due to impurities of one sort or another.
So nonlinearity of the HD PE, rather than being by intelligent design, would be by accidental impurity, due to lax quality control in the manufacture of the industrially supplied bulk HD PE used by NASA Eagleworks.

That's a possibility.  Could also explain the difference between some chambers w/ and w/o dielectric ???

Still, what types and how much impurity would be necessary to take place in order to have significant nonlinear effects?

Good question.  One of the papers Mulletron brought up:

http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=6690216

has interesting curves showing the frequency shifts.   Maybe Mulletron has a PT input on this point ?

Dr. Rodal & Notsosureofit:

We had an interesting failure in the Eagleworks lab yesterday.  That being I was getting ready to pull a vacuum on our copper frustum mounted in its "reverse" or to the right thrust vector position and ran a preliminary data un to see if it was performing in air as it had two weeks ago just before our last RF amplifier died.  Sadly it wasn't for it was producing less than half of what it did before and in the wrong direction!   

I had Dr. White come in and take a look over my latest test article installation last night and he found that the center 1/4"-20 nylon PE disc mounting bolt that holds the second PE disc to the small OD frustum's PCB endplate was no-longer tensioned as it had been before.  In fact it had partially melted at the interface between the two PE discs thus relieving the strain induced by its bolts threads and nut.  (There are three ~1.00" 1/4-20 nylon bolts mounted on a ~2.00" radius spaced every 120 degrees that hold the first PE disc to the PCB end cap.   There is then a layer of 3/4" wide office scotch tape at the interface between the first and second PE discs and the center 1/4"-20 nylon bolt that hold second PE disc to the first PE disc.) 

Apparently not having the PE discs firmly mounted to the frustum's small OD end cap hindered the thrust producing mechanism that conveys the generated forces in the PE to the copper frustum.  And/or the melted nylon was hogging all the RF energy in the PE discs due to its higher dissipation factor in its semiliquid state.  Either way it looks like there is a high E-field volume where this center nylon bolt hangs out while running in the TM212 resonant mode.  Too bad Teflon bolts are so weak even in comparison to the nylon, for its dissipation factor is at least two orders of magnitude lower than the nylon's.

Best, Paul M. 

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