Author Topic: EM Drive Developments - related to space flight applications - Thread 2  (Read 2102844 times)

Offline Notsosureofit

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That would certainly throw all kinds of motion induced errors into the mix.  Best to carefully rebuild the original configuration.


Anyway, there is an interesting, if probably coincidence, between the reported results in the above paper using a 19 period optical cavity.  When you compare their (PT transition) frequency shift to a 2 period cavity you get 2.1 GHz which is of the order of magnitude of the shift (~ 1.7 GHz) the calculation for the Brady cavity.

Probably means nothing....but curious.

« Last Edit: 02/21/2015 05:33 PM by Notsosureofit »

Online Rodal

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That would certainly throw all kinds of motion induced errors into the mix.  Best to carefully rebuild the original configuration.


Anyway, there is an interesting, if probably coincidence, between the reported results in the above paper using a 19 period optical cavity.  When you compare their (PT transition) frequency shift to a 2 period cavity you get 2.1 GHz which is of the order of magnitude of the shift (~ 1.7 GHz) the calculation for the Brady cavity.

Probably means nothing....but curious.

Using a unidirectional reflectionless PT grating with a nonlinear silicon distributed Bragg reflector (DBR) cavity consisting of: 20 modulation periods of 2 Pi /q = 0.27 micro meters



EDIT;

<<the emergence of the Optical Rogue Waves (ORWs) ( http://en.wikipedia.org/wiki/Optical_rogue_waves  ) has been explored based on the system parameters>>

http://arxiv.org/ftp/arxiv/papers/1312/1312.3400.pdf



« Last Edit: 02/21/2015 06:41 PM by Rodal »

Online 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?

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.

Great information, thank you so much for sharing it.   :)

Great discoveries have been made in the past as a result of "failures"

The information that:

" 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."

is very valuable and telling of the importance, not only of the dielectric, but of the dielectric being connected to the small flat end.  One idea that had been floated in this thread was to do a test without the small flat end to see what happens.  This "failure" indicates that removal of the copper (on the inside) small flat end may result in significant loss of thrust force.
« Last Edit: 02/21/2015 07:27 PM by Rodal »

Offline Mulletron

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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...
http://www.mcmaster.com/#standard-plastic-rods/=w0bzy0
Website won't let me direct link to it. Can't find that 6.25" dimension. See Rigid HDPE Polyethylene.

Quote
Can anybody present quantitative experimentally-measured data showing significant PT asymmetry or nonlinear frequency effects....
I'd suggest changing significant to any. I doubt this will come because PT symmetry breaking doesn't come out of the box, it is a spontaneous symmetry break brought on by the specific conditions the material is subject to. I honestly think an expert is going to have to examine the spontaneous PT symmetry breaking in Emdrive in order to conclusively rule it in or out. I think the best way to figure it out is to substitute the PE with a perfectly ordered chiral material and see where the thrust goes. As we've discussed, PT PE and PTFE have an achiral backbone, yet gain chirality through twisting around the C=C bonds. So there is much room for improvement.
http://www.esrf.eu/UsersAndScience/Publications/Highlights/2011/scm/scm4
http://goo.gl/p7VVKJ
http://goo.gl/aO9E2Z pg94

I'm digging around in PT symmetry more to see if there any analogues to Emdrive to be found, like asymmetric waveguide or high filed strengths, which might hint that this is or is not in fact what is happening. Got hints to those ones in bold from the optical literature posted. It is clear from researching the issue that the phenomenon is well understood.

Given the eerie performance of TE012 combined with the high magnetic field strength at the small end, and the theory making use of the magnetic field to "transfer momentum" it seems likely but not proven this is really happening.

« Last Edit: 02/22/2015 01:42 AM by Mulletron »
Challenge your preconceptions, or they will challenge you. - Velik

Offline Mulletron

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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. ...........

Best, Paul M.
That dielectric is definitely doing something important. Would be interesting what would happen if a piece of gold leaf was sandwiched behind the PE, just to see what happens to the thrust. This is a hint to an earlier post I made about the perceived importance of the air/dielectric/copper interface, which might me true after all, if there is a giant Casimir force inside the cavity.
http://forum.nasaspaceflight.com/index.php?topic=36313.msg1329454#msg1329454


« Last Edit: 02/21/2015 11:47 PM by Mulletron »
Challenge your preconceptions, or they will challenge you. - Velik

Online 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...
http://www.mcmaster.com/#standard-plastic-rods/=w0bzy0
Website won't let me direct link to it. Can't find that 6.25" dimension. See Rigid HDPE Polyethylene.

...

Under Performance of Plastics it directs you to a .pdf  that lists

450-1,800  Dielectric Strength, volts/0.001inch

that is 17.72 million V/m (on the low end) that's a little lower than the lowest value listed here:  http://hypertextbook.com/facts/2009/CherryXu.shtml but the same minimum listed here: http://www.rfcafe.com/references/electrical/dielectric-constants-strengths.htm


************

Biggest diameter they list is 6.00 inches:

Rigid HDPE Polyethylene Rod, 6" Diameter

Length, ft.
1
2
3
4
5
6
7
8
« Last Edit: 02/21/2015 07:51 PM by Rodal »

Offline Flyby

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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.

Good to see all Chinese drawings at once, I was not familiar with all of them... thnx for that, flux_

The only one that strikes me to be a real world technical drawing would be the bottom right one.
All the rest will most likely be pure schematic/concept drawings, intended rather to explain something and not intended to represent actual build systems.
I'm not doubting they made several designs and tests, but I seriously doubt that every drawing made relates back to a real test or model. Most of these drawings simply do not hold enough technical info to be credible "as build" plans. You can not use those drawings and proportions to base a real build model on them.
Technical drawings do follow a certain code and stick to general conventions.
The majority of those drawings do not follow those... Hence why I say that they "do not correlate" with any real made object. They're not construction drawings, but function as communication drawings, explaining the workings, concepts and layouts. You should not base dimensional extrapolations for a real world object on them.

But hey, I'm merely sharing 30 years of experience handling technical drawings... if you feel I'm wrong on that assumption... I can live with that...the earth will continue spinning.. ;)

Online 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

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.

Good to see all Chinese drawings at once, I was not familiar with all of them... thnx for that, flux_

The only one that strikes me to be a real world technical drawing would be the bottom right one.
All the rest will most likely be pure schematic/concept drawings, intended rather to explain something and not intended to represent actual build systems.
I'm not doubting they made several designs and tests, but I seriously doubt that every drawing made relates back to a real test or model. Most of these drawings simply do not hold enough technical info to be credible "as build" plans. You can not use those drawings and proportions to base a real build model on them.
Technical drawings do follow a certain code and stick to general conventions.
The majority of those drawings do not follow those... Hence why I say that they "do not correlate" with any real made object. They're not construction drawings, but function as communication drawings, explaining the workings, concepts and layouts. You should not base dimensional extrapolations for a real world object on them.

But hey, I'm merely sharing 30 years of experience handling technical drawings... if you feel I'm wrong on that assumption... I can live with that...the earth will continue spinning.. ;)
1) I was just asking for a link to understand what you were referring to. 

2) I was not intending to use any of those drawings to build anything but instead to conduct calculations that take a fraction of a second to calculate.  Calculating the frequencies and mode shapes from an estimated geometry and comparing it with the published results quickly tells me how representative was the drawing of the actual build system.  That's how for example, we quickly eliminated the @Fornaro estimate of geometry and zeroed in on the @aero and @Mulletron estimates, for example.

Thanks
« Last Edit: 02/21/2015 08:52 PM by Rodal »

Offline Notsosureofit

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@ Star-Drive

We've battled the Nylon vs Teflon fasteners for years in our plasma chambers.  These days we replace the Nylon ones every run.  Teflon holds up very well, just won't take much mechanical load.

Offline Notsosureofit

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That would certainly throw all kinds of motion induced errors into the mix.  Best to carefully rebuild the original configuration.


Anyway, there is an interesting, if probably coincidence, between the reported results in the above paper using a 19 period optical cavity.  When you compare their (PT transition) frequency shift to a 2 period cavity you get 2.1 GHz which is of the order of magnitude of the shift (~ 1.7 GHz) the calculation for the Brady cavity.

Probably means nothing....but curious.

Using a unidirectional reflectionless PT grating with a nonlinear silicon distributed Bragg reflector (DBR) cavity consisting of: 20 modulation periods of 2 Pi /q = 0.27 micro meters



EDIT;

<<the emergence of the Optical Rogue Waves (ORWs) ( http://en.wikipedia.org/wiki/Optical_rogue_waves  ) has been explored based on the system parameters>>

http://arxiv.org/ftp/arxiv/papers/1312/1312.3400.pdf






Interesting!

Quick read makes me think we would be below the PT transition.  At some power level the divergence would increase dramatically and so would the thrust.  But this is very speculative!!

Offline Flyby

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1) I was just asking for a link to understand what you were referring to. 

2) I was not intending to use any of those drawings to build anything but instead to conduct calculations that take a fraction of a second to calculate.  Calculating the frequencies and mode shapes from an estimated geometry and comparing it with the published results quickly tells me how representative was the drawing of the actual build system.  That's how for example, we quickly eliminated the @Fornaro estimate of geometry and zeroed in on the @aero and @Mulletron estimates, for example.

Thanks
Sigh...rereading my post, my answer does sound unnecessarily aggressive.... My apologies for that.
Lame excuse, but it's getting late here...I'd better go get some good night of sleep... :-X

Offline Mulletron

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I think the following concerns by @seanmcarroll have been addressed in this thread:

Quote
There is no such thing as a ‘quantum vacuum virtual plasma,’ so that should be a tip-off right there. There is a quantum vacuum, but it is nothing like a plasma. In particular, it does not have a rest frame, so there is nothing to push against, so you can’t use it for propulsion. The whole thing is just nonsense. They claim to measure an incredibly tiny effect that could very easily be just noise.” There is no theory to support the result, and there is no verified result to begin with.
source: http://blogs.discovermagazine.com/outthere/2014/08/06/nasa-validate-imposible-space-drive-word/#.VOk1XC6pjSg

We know it isn't a plasma. We know it doesn't have a rest frame, and accept you can't push against it, but you likely can use it for propulsion under the circumstances we've explored here. The device has also been successfully tested in vacuum.

« Last Edit: 02/22/2015 12:58 AM by Mulletron »
Challenge your preconceptions, or they will challenge you. - Velik

Online Rodal

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Well Sean Carroll, himself wrote, when discussing the Quantum Vacuum stability:

Quote from: Sean Carroll
observers shouldn’t take too seriously the grandiose claims of theorists about what is and is not possible; they should do their experiments and see what the data imply. It would be a shame to miss out on a fantastic discovery because you believed some theorist who told you it couldn’t possibly be there.

http://www.preposterousuniverse.com/blog/2004/09/14/vacuum-stability/

Online Rodal

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I think the following concerns by @seanmcarroll have been addressed in this thread:

Quote
...and there is no verified result to begin with.
source: http://blogs.discovermagazine.com/outthere/2014/08/06/nasa-validate-imposible-space-drive-word/#.VOk1XC6pjSg
...The device has also been successfully tested in vacuum.

Probably Sean Carroll still will maintain that "there is no verified result to begin with" because the test under hard vacuum has not been verified at independent institutions, particularly in academia.  That's why I always thought that replicating the tests #1) at John Hopkins (if given a choice between Glenn, JPL and John Hopkins) and #2) at JPL, and #3) NASA Glenn, would have provided the most credibility regarding the subject of independent verification.

He will probably remind readers of the Cold Fusion claims (and similar examples) where Martin Fleischmann (then one of the world's leading electrochemists) reported "anomalous heat" (interesting: same word used in Brady's report title !), then many scientists tried to replicate their experiment but hopes fell with the large number of negative replications, and the withdrawal of many positive replications.
« Last Edit: 02/22/2015 02:07 AM by Rodal »

Online Rodal

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Oh, actually, there is a much better #1 in my book, than those three places: to independently verify the NASA Eagleworks test at Notsosureofit's lab  !

If Notsosureofit verifies it, then it is a slam dunk, a guaranteed sure thing, and we are on our way !
« Last Edit: 02/22/2015 02:12 AM by Rodal »

Offline Star-Drive

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@ Star-Drive

We've battled the Nylon vs Teflon fasteners for years in our plasma chambers.  These days we replace the Nylon ones every run.  Teflon holds up very well, just won't take much mechanical load.

Notsosureofit:

We've fried a number of nylon bolts and have found that the best way to keep them from getting cooked is to keep them out of the high E-field regions in the cavity.  For Instance we tested the copper frustum in its TM010 mode and mounted a 5.0 inch OD by 1.0" thick PTFE disk at the center of the large OD end cap of the copper frustum with one 1/4-20 nylon bolt.  We got some large thrust signatures in that configuration, see attached slide, but the dam nylon bolt kept melting and dropping the PTFE discs into the main body of the cavity.  Brother did that look like a magnitude 9 earthquake on our uN resolution force measurement system! 

That said, I'm wondering if the nylon bolts themselves could be contributing to the measured force we are seeing?  It has a much smaller volume than the PE and PTFE discs, but they have a much higher dissipation factor than PE or PTFE that could translate into more work done converting E&M momentum into mechanical forces.

Best, Paul M.
« Last Edit: 02/22/2015 05:17 AM by Star-Drive »
Star-Drive

Offline DIYFAN

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... then many scientists tried to replicate their experiment but hopes fell with the large number of negative replications, and the withdrawal of many positive replications.

Sad but true.  There is, however, somewhat of a renaissance occurring right now with LENR+ (commercially viable LENR).  The current most promising method uses a mixture of nickel powder, iron powder, and LiAlH4 heated to 1100 C under pressure.  Multiple universities in the U.S. have recently opened programs with full funding to investigate LENR+.  Don't count this phenomena out entirely.  Coupled with an EM Drive, the space flight applications become very interesting.  Admittedly, controversy abounds, and it is still early to say what the probability of success and implications might be, but nonetheless, it doesn't hurt to keep a finger on the pulse on the most current efforts underway. 

Offline RotoSequence

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We've fried a number of nylon bolts and have found that the best way to keep them from getting cooked is to keep them out of the high E-field regions in the cavity.  For Instance we tested the copper frustum in its TM010 mode and mounted a 5.0 inch OD by 1.0" thick PTFE disk at the center of the large OD end cap of the copper frustum with one 1/4-20 nylon bolt.  We got some large thrust signatures in that configuration, see attached slide, but the dam nylon bolt kept melting and dropping the PTFE discs into the main body of the cavity.

Are there low E-field regions across multiple resonance modes that can be used as mounting points to secure the PTFE discs?

Online Rodal

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We've fried a number of nylon bolts and have found that the best way to keep them from getting cooked is to keep them out of the high E-field regions in the cavity.  For Instance we tested the copper frustum in its TM010 mode and mounted a 5.0 inch OD by 1.0" thick PTFE disk at the center of the large OD end cap of the copper frustum with one 1/4-20 nylon bolt.  We got some large thrust signatures in that configuration, see attached slide, but the dam nylon bolt kept melting and dropping the PTFE discs into the main body of the cavity.

Are there low E-field regions across multiple resonance modes that can be used as mounting points to secure the PTFE discs?

@Rotosequence and @Star-Drive

Excellent question by @Rotosequence.  Yes, for a given mode-shape there are E-field regions with very low E-Field that could be used as mounting points to secure the PTFE discs.  For example, for TM212, here they are (low E field is represented by the dark blue color):



To answer whether they exist "across multiple resonance modes" , depends on the natural frequency being excited and the modes being excited.  If NASA could consistently excite a TE (transverse electric) mode instead of a TM (transverse magnetic) mode, there would be no electric field whatsoever on the entire surface of the flat ends.  So that's another advantage for exciting mode TE012 (if possible to be done consistently), which is the mode in the Brady et.al. report reported to have, by far, the largest thrust per power input.  Also, the experiments conducted by Prof. Juan Yang in China, that reached the highest thrust forces (by far) reported for an EM drive, were reported to be TE modes.

If NASA for the time being (due to the problems of consistently being able to excite a given mode) cannot consistently excite TE012 or other TE modes, and needs to continue exciting TM modes like TM212, then one possible solution would be to keep the antenna in exactly the same place for every test and place the bolts in the locations of minimum E-field.   Because the azimuthal (circumferential) location of the low electric field regions rotate in the azimuthal direction (with the center of the flat circular end as the axis of rotation) with changes in the azimuthal location of the antenna. With the antenna in a fixed location, and for a fixed frequency and mode shape, one could then mount the bolts in the locations of minimum E-field.
« Last Edit: 02/22/2015 12:30 PM by Rodal »

Online aero

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Perhaps a more general solution to the problem of melting nylon bolts would be to search diligently for a material that does not melt.

While perhaps more difficult to obtain (read that as "custom manufacture") bolts can be made from almost any solid. I can just imagine Paul with his pen-knife carving a bolt from a wooden dowel rod. Or baking a ceramic bolt in this wife's kitchen oven.

Seriously though, the bolts problem is a materials issue. What are the necessary characteristics of the bolts, then what are the various materials that satisfy those specifications?

Now that we know the specifications, who wants to volunteer to make 4 bolts?

Edit Add: Or maybe there exists an epoxy (glue) that would serve to attach the dielectric disks?
« Last Edit: 02/22/2015 02:38 PM by aero »
Retired, working interesting problems

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