Author Topic: EM Drive Developments - related to space flight applications - Thread 3  (Read 1801679 times)

Online Rodal

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I tried to define what I meant by solenoidal: circulating around the axis of the frustum The Maxwell Field has 4 potentials, A^u=(phi, A), u = 0,1,2,3,  "A" is parallel to the axis of the frustum. I understand solenoidal refers to any vector field that does not have divergence, but I was trying to describe the field wrapping around the axis, not a torroidal "B" field wrapping around the minor circumference. In QFT, the best example is a superconductor, where "phi" simply represents the scalar phase of the field.

I understand oscillating from TE to TM, I'm just thinking out loud and you're correct it applies in both modes.  A^u exists on both sides of the conductors, regardless of the mode.

Todd

Thanks for the explanation.

My understanding is that A--Bohm effect takes place when the wave function of a charged particle passing around a long solenoid experiences a phase shift as a result of the enclosed magnetic field, despite the magnetic field being negligible in the region through which the particle passes and the particle's wavefunction being negligible inside the solenoid.

What charged particles would be involved here in this effect ?
or you are just thinking aloud how the EM Drive system can be inherently open, and you think that charged particles are not necessary.  If so, then what is it open in relationship to ?

(This brings to mind again Prof. Yang inviting the reader to think about charged particles in reference to the EM Drive)
« Last Edit: 06/04/2015 04:15 PM by Rodal »

Offline rfmwguy

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A perfectly reasonable argument for calling it an open system is to acknowledge that vacuum fluctuations of the electromagnetic field are common to both inside and outside the cavity. They are everywhere.

Agreed.  In addition I can think of a few other ways that the system could be open and I'm sure there are others. I was putting this list together on my walk yesterday morning

1. Earth's, Sun's, Galaxy's electromagnetic field,
2. Earth's, Sun's, Galaxy's gravitational field,
3. Unruh radiation,
4. Neutrinos, (doubtful)
5. Higgs Fields,
6. Quantum Vacuum,
7. 3 + Nth spatial dimension,
8. 3 + Nth spatial dimension + Plank Brane,
9. Quantum Tunneling (though this is unlikely due to thickness of the copper)
10. Others?

I would like to add to, and cross off of, this list :)

Possible add (?) ...Electrostatics

Guess I should state why...my experience with high voltage and their ability to generate static electric fields.
« Last Edit: 06/04/2015 04:09 PM by rfmwguy »

Offline phaseshift

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The choice here is either not to include the experiments by Iulian (if you think that his tests self-nullify each other, and therefore you think that you cannot put any  numbers in the common format) or, if to include them, to put a number for the experiments.  @aero wrote, that Iulian's experiments should remain in the table.  In that case, if you think that the quoted numbers from deltaMass are incorrect and misrepresent the true tests, what numbers for Iulian tests would you suggest to put in the table under the agreed format?

My concern is a lot of noise in the data table.  Iulian's first experiment, while important for him to do, probably isn't a data point that adds to our collective knowledge. It seems to me that there is a threshold above which the experiment needs to be in order for its data to be added.

Having the null tests and failed tests listed on the wiki is also important.

Maybe they are all failed tests so far ;) I don't know what the threshold would be, but putting every experiment's results in the table without any controls seems counterproductive.

Maybe its up to the experimenter.  "I have ruled out every experimental artifact that I can, here's how I did this, and here are the results".
« Last Edit: 06/04/2015 04:51 PM by phaseshift »
"It doesn't have to be a brain storm, a drizzle will often do" - phaseshift

Offline phaseshift

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Wouldn't the tunnelling effect also be constrained by conservation of momentum and therefore apply at both ends of the frustrum?
You have to look at the energy density regarding radiation pressure, and don't ignore the lateral conical walls.
Then perform a quantum tunneling analysis.  Momentum will be favored to one side if there is a gradient of emission.

correct and
The tunneling effect acts instantaneous. At the moment a photon is tunneling it impulse acts, that's like its reflected in a wall <z (lower qua the real length of the cavity). There has to be a blue shift of the signal means higher frequency like calculated r and z dependent.

Are you sure that's a net blue shift?  The frustum has to gain momentum which means the photon loses energy and red shifts.  Is the blue shift something that photon's do when they tunnel?
Yes, if there is a potential barrier (cutoff frequency, diameter )most of the photons would be reflected (may be at the sidewall may be at the energy barrier) but some photons able to tunneling that barrier in just zero time, i think than the cavity acts like shorter than it is.
The small end looks like it is narrow to the small end. Its more a intuitiv thing, i have the luck to work with conical cavities for special applications. Got network analyser, Spectrum Analyzer, circulator, load, tapered cavities all available and i am able to build conical cavities like a want but in K-Band area
 8)

I'm just wondering.. if tunneling happens instantaneously (in the literal sense), then there is no time to measure anything - it happens without any dt . Hence, I don't think it can be said that photons increase or decrease frequency during the transition through the barrier.. if there is null time passing, then logically no measurements can take place, from which we can derive a claim about how frequencies of photons might change during a null time transition.
;)

Then they don't change during the null transition.
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Offline saucyjack

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What about:
Material ablation/ejection
Thermal convection outside of the cavity from heated walls
The force of the spring on Iulian's torque arm
Accumulating errors in the digital scale from rf exposure
Thermal buckling causing a shift in the COM
Forces between wires connected to the frustum and wires that are not
etc. 


I would like to see a comprehensive enumeration of every experimental artifact that should be compensated/accounted for and get it on the wiki or some place that the experimenters have immediate access to.

I added this list to http://emdrive.wiki/Iulian_Berca as well as a link to the existing, more general discussion of error sources at http://emdrive.wiki/Possible_Error_Sources

For both, feel free to add/edit as you see fit.

Online Rodal

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My concern is a lot of noise in the data table.  Iulian's first experiment, while important for him to do, probably isn't a data point that adds to our collective knowledge. It seems to me that there is a threshold above which the experiment needs to be in order for its data to be added.

Having the null tests and failed tests listed on the wiki is also important.
Well, if anyone doesn't like to take Iulian's data (or any other data in the spreadsheet) into account they are free to do so.  At this point none of the experimental data in the table has been scientifically validated by replication at various other scientific institutions.

Until that happens, if anyone wants to draw differences, there is one test that stands far above the others: NASA's test in vacuum.

After more than 100 years of experimenters reporting radiation pressure measurements problems with tests run in ambient conditions, I don't see how anyone could consider the tests in ambient conditions to be on an equal footing with NASA's tests in vacuum.

Particularly when the researchers conducting tests in ambient conditions have not used a wired mesh for the end plates as done by the first researcher to successfully measure radiation pressure in microwave waveguides (Cullen in 1951). 

So much for a list of issues, when the main known issue ("gas effect") is not addressed, either by testing in vacuum or by using a wire mesh.
« Last Edit: 06/04/2015 05:01 PM by Rodal »

Offline WarpTech

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Thanks for the explanation.

My understanding is that A--Bohm effect takes place when the wave function of a charged particle passing around a long solenoid experiences a phase shift as a result of the enclosed magnetic field, despite the magnetic field being negligible in the region through which the particle passes and the particle's wavefunction being negligible inside the solenoid.

What charged particles would be involved here in this effect ?
or you are just thinking aloud how the EM Drive system can be inherently open, and you think that charged particles are not necessary.  If so, then what is it open in relationship to ?

(This brings to mind again Prof. Yang inviting the reader to think about charged particles in reference to the EM Drive)

The field, A intersects the copper frustum, so the charges are the current flowing in the copper. When using Maxwell's equations, reduced to density and pressure, all the relative phase information is hidden. Using the A-Bohm effect and the quantum mechanical path integral approach, the relative phases of the field and the currents are taken into consideration, at every point along the path.

Regarding the open system, y'all were talking about photon tunneling yesterday and that reminded me that the gauge field, A^u cannot be shielded. In QED, A^u is a probability distribution of photons, which can be expressed as both particles and waves.

Todd



Offline phaseshift

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My concern is a lot of noise in the data table.  Iulian's first experiment, while important for him to do, probably isn't a data point that adds to our collective knowledge. It seems to me that there is a threshold above which the experiment needs to be in order for its data to be added.

Having the null tests and failed tests listed on the wiki is also important.
Well, if anyone doesn't like to take Iulian's data (or any other data in the spreadsheet) into account they are free to do so.  At this point none of the experimental data in the table has been scientifically validated by replication at various other scientific institutions.

Until that happens, if anyone wants to draw differences, there is one test that stands far above the others: NASA's test in vacuum.

After more than 100 years of experimenters reporting radiation pressure measurements problems with tests run in ambient conditions, I don't see how anyone could consider the tests in ambient conditions to be on an equal footing with NASA's tests in vacuum.

Particularly when the researchers conducting tests in ambient conditions have not used a wired mesh as done by the first researcher to successfully measure radiation pressure in microwave waveguides (Cullen in 1951).

Absolutely agree. When that page has 100+ experimental results maybe then it will become clearer how to proceed.

"It doesn't have to be a brain storm, a drizzle will often do" - phaseshift

Offline Jared

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My concern is a lot of noise in the data table.  Iulian's first experiment, while important for him to do, probably isn't a data point that adds to our collective knowledge. It seems to me that there is a threshold above which the experiment needs to be in order for its data to be added.

Having the null tests and failed tests listed on the wiki is also important.
Well, if anyone doesn't like to take Iulian's data (or any other data in the spreadsheet) into account they are free to do so.  At this point none of the experimental data in the table has been scientifically validated by replication at various other scientific institutions.

Until that happens, if anyone wants to draw differences, there is one test that stands far above the others: NASA's test in vacuum.

After more than 100 years of experimenters reporting radiation pressure measurements problems with tests run in ambient conditions, I don't see how anyone could consider the tests in ambient conditions to be on an equal footing with NASA's tests in vacuum.

Particularly when the researchers conducting tests in ambient conditions have not used a wired mesh for the end plates as done by the first researcher to successfully measure radiation pressure in microwave waveguides (Cullen in 1951).  So much for a list of issues, when the main known issue ("gas effect") is not addressed, either by testing in vacuum or by using a wire mesh.

Maybe transparency could be increased if the "Experimental Results" table in the Wiki featured an additional column describing the basic ambient conditions of each test? E.g. "Vacuum", "Partial Vacuum", etc.

[EDIT] I see this is basically already there in the "Pressure" column ...
« Last Edit: 06/04/2015 05:07 PM by Jared »

Online Rodal

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My concern is a lot of noise in the data table.  Iulian's first experiment, while important for him to do, probably isn't a data point that adds to our collective knowledge. It seems to me that there is a threshold above which the experiment needs to be in order for its data to be added.

Having the null tests and failed tests listed on the wiki is also important.
Well, if anyone doesn't like to take Iulian's data (or any other data in the spreadsheet) into account they are free to do so.  At this point none of the experimental data in the table has been scientifically validated by replication at various other scientific institutions.

Until that happens, if anyone wants to draw differences, there is one test that stands far above the others: NASA's test in vacuum.

After more than 100 years of experimenters reporting radiation pressure measurements problems with tests run in ambient conditions, I don't see how anyone could consider the tests in ambient conditions to be on an equal footing with NASA's tests in vacuum.

Particularly when the researchers conducting tests in ambient conditions have not used a wired mesh as done by the first researcher to successfully measure radiation pressure in microwave waveguides (Cullen in 1951).

Absolutely agree. When that page has 100+ experimental results maybe then it will become clearer how to proceed.
I don't particularly agree with the focus and wording (I see the word "amateur" is present in the wiki) for Iulian Berca's experiment, when the same degree of stringent rigor is not dedicated to the tests reported by very small private companies in the UK and the USA and a University in China for their tests in ambient conditions.

The one test in vacuum (NASA) only shows ~300 times the Force/Power Multiple of Photon Rocket.  If you take into account the measurement with the EM Drive rotated by 180 degrees, then the measurement is ~100 times the Force/Power Multiple of Photon Rocket.

The measurements giving 72,830 times the Force/Power Multiple of Photon Rocket were conducted in ambient conditions by a very, very small private company, and nothing much more has been disclosed about their experimental conditions.

Iulian Berca at least provided all the dimensions of his experimental EM Drive,  while the private company in question has not provided all the dimensions of the EM Drive being featured in the spreadsheet.  We were reduced at guessing the dimensions by looking at photographs ?   

And none of the experiments by Prof. Yang are in the spreadsheet because so little has been disclosed about her experiments.

So, is the focus and wording on Berca fair, taking into account that we cannot even put Yang's experimental results in the spreadsheet and that the really small private company has not even released the cavity dimensions and other vital data ?


:(



ADDED:

Is it meaningful to draw a meaningful distinction between private individuals and really tiny "private companies" supplying results?  Private individuals form their own "companies" for tax purposes.

How many researchers were involved in the tiny US private company that conducted the superconducting test featured in the spreadsheet?    and in the tiny UK private company ?

Concerning the validity of the tests, how about an examination of the validity of the superconducting test at that tiny US company ? Is there a calculation for the superconducting test device being oriented in the pointing up and pointing down position?  [Berca performed the test in both orientations]

Should the superconducting test also be removed ?

« Last Edit: 06/04/2015 06:19 PM by Rodal »

Offline tchernik

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My concern is a lot of noise in the data table.  Iulian's first experiment, while important for him to do, probably isn't a data point that adds to our collective knowledge. It seems to me that there is a threshold above which the experiment needs to be in order for its data to be added.

Having the null tests and failed tests listed on the wiki is also important.
Well, if anyone doesn't like to take Iulian's data (or any other data in the spreadsheet) into account they are free to do so.  At this point none of the experimental data in the table has been scientifically validated by replication at various other scientific institutions.

Until that happens, if anyone wants to draw differences, there is one test that stands far above the others: NASA's test in vacuum.

After more than 100 years of experimenters reporting radiation pressure measurements problems with tests run in ambient conditions, I don't see how anyone could consider the tests in ambient conditions to be on an equal footing with NASA's tests in vacuum.

Particularly when the researchers conducting tests in ambient conditions have not used a wired mesh as done by the first researcher to successfully measure radiation pressure in microwave waveguides (Cullen in 1951).

Absolutely agree. When that page has 100+ experimental results maybe then it will become clearer how to proceed.
I don't particularly agree with the focus and wording (I see the word "amateur" is present in the wiki) for Iulian Berca's experiment, when the same degree of stringent rigor is not dedicated to the tests reported by a private company in the UK and a University in China for their tests in ambient conditions.

The one test in vacuum (NASA) only shows ~300 times the Force/Power Multiple of Photon Rocket.  If you take into account the measurement with the EM Drive rotated by 180 degrees, then the measurement is ~100 times the Force/Power Multiple of Photon Rocket.

The measurements giving 72,830 times the Force/Power Multiple of Photon Rocket were conducted in ambient conditions by a private company, and nothing much more has been disclosed about their experimental conditions.

Iulian Berca at least provided all the dimensions of his experimental EM Drive,  while the private company in question has not provided all the dimensions of the EM Drive being featured in the spreadsheet.  We were reduced at guessing the dimensions by looking at photographs ?   

And none of the experiments by Prof. Yang are in the spreadsheet because so little has been disclosed about her experiments.

So, is the focus and wording on Berca fair, taking into account that we cannot even put Yang's experimental results in the spreadsheet and that the UK private company has not even released the cavity dimensions and other vital data ?


:(

2 words: scientific elitism.

If they want to somewhat avoid the flagrant appearance of falling into it, the list of experiments should be divided between public, private and individually funded experimental setups.

Then people can take whatever interpretation they like about the quality of the experiment from those true and irrefutable facts.
« Last Edit: 06/04/2015 05:27 PM by tchernik »

Offline kml

Iulian Berca at least provided all the dimensions of his experimental EM Drive,  while the private company in question has not provided all the dimensions of the EM Drive being featured in the spreadsheet.  We were reduced at guessing the dimensions by looking at photographs ?   

This is an excellent point.   Science (open source or not) only works with full disclosure.    I encourage experimenters to publish/post detailed specifications of their experiment as built and operated.  That includes designs, dimensions, materials, coatings, dielectrics, feedpoint and sampling interfaces, operating frequency, resonant mode(s), ambient conditions (temperature, pressure, humidity), and methods of measuring forces (including calibration).  Tests should be performed in as many orientations as possible.

So many of the existing results leave open questions about the above details.  This limits the usefulness of the results.    I am still acquiring the equipment and parts for my experiment but I will publish the above details along with any results.


Offline phaseshift

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My concern is a lot of noise in the data table.  Iulian's first experiment, while important for him to do, probably isn't a data point that adds to our collective knowledge. It seems to me that there is a threshold above which the experiment needs to be in order for its data to be added.

Having the null tests and failed tests listed on the wiki is also important.
Well, if anyone doesn't like to take Iulian's data (or any other data in the spreadsheet) into account they are free to do so.  At this point none of the experimental data in the table has been scientifically validated by replication at various other scientific institutions.

Until that happens, if anyone wants to draw differences, there is one test that stands far above the others: NASA's test in vacuum.

After more than 100 years of experimenters reporting radiation pressure measurements problems with tests run in ambient conditions, I don't see how anyone could consider the tests in ambient conditions to be on an equal footing with NASA's tests in vacuum.

Particularly when the researchers conducting tests in ambient conditions have not used a wired mesh as done by the first researcher to successfully measure radiation pressure in microwave waveguides (Cullen in 1951).

Absolutely agree. When that page has 100+ experimental results maybe then it will become clearer how to proceed.
I don't particularly agree with the focus and wording (I see the word "amateur" is present in the wiki) for Iulian Berca's experiment, when the same degree of attention is not focused on the tests reported by a private company in the UK and a University in China for their tests in ambient conditions.

The one test in vacuum (NASA) only shows ~300 times the Force/Power Multiple of Photon Rocket.  If you take into account the measurement with the EM Drive rotated by 180 degrees, then the measurement is ~100 times the Force/Power Multiple of Photon Rocket.

The measurements giving 72,830 times the Force/Power Multiple of Photon Rocket were conducted in ambient conditions by a private company, and nothing much more has been disclosed about their experimental conditions.

Iulian Berca at least provided all the dimensions of his experimental EM Drive,  while the private company in question has not provided all the dimensions of the EM Drive being featured in the spreadsheet.  We were reduced at guessing the dimensions by looking at photographs ?   

And none of the experiments by Prof. Yang are in the spreadsheet because so little has been disclosed about her experiments.

So, is the focus and wording on Berca fair, taking into account that we cannot even put Yang's experimental results in the spreadsheet and that the UK private company has not even released the cavity dimensions and other vital data ?


:(

Yes, its fair.  His is the first experiment we are able to focus on given his accessibility.  The focus itself is not a judgement by anyone here, its simply that we have the data from him and are able to communicate with him - unlike the rest of the experimenters (in general).

I think it is too soon for Iulian to be releasing results though.  His first video was exciting for sure. To see someone take concrete steps like this is encouraging and amazing.  However, I'm sure he knows that there are numerous artifacts that he needs to take into account before he can truly say, "I think I'm seeing thrust."  Sharing the results of his experiment as he progresses gives us all insight into his process and how he is handling the artifacts - but adding 'data' to a table indicating the positive measurement of thrust seems premature.  Dr. Rodal, you are absolutely right that the same criteria is not being applied to the other experimenters except that they reached that point in their experiment where they proclaimed "I think I'm seeing thrust" and 'published' their results.  It's just unfortunate that they didn't adequately share all of the data that they could have.

So, while I would like to hear updates from Iulian on his progress I would rather not add his 'data' to the table until he says "I think I'm seeing thrust", but not just due to the excitement of the moment.

"It doesn't have to be a brain storm, a drizzle will often do" - phaseshift

Offline wallofwolfstreet

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What about:
Material ablation/ejection
Thermal convection outside of the cavity from heated walls
The force of the spring on Iulian's torque arm
Accumulating errors in the digital scale from rf exposure
Thermal buckling causing a shift in the COM
Forces between wires connected to the frustum and wires that are not
etc. 


I would like to see a comprehensive enumeration of every experimental artifact that should be compensated/accounted for and get it on the wiki or some place that the experimenters have immediate access to.

The emdrive wiki has a rudimentary list - can we work to flesh it out? :)

I can try to get the ball rolling on that.  If anyone is allowed to edit the wiki, I will try to do so later.

Thermal effects

1) Convection from unevenly heated frustum walls ==> net force.

2) Infrared radiation - limited to force of perfectly collimated photon rocket, so should be negligible.

3) Buoyancy - expanding air is expelled from the cavity, resulting in a lower air density inside than outside.  Note that this only applies to a cavity that is not hermetically sealed if buckling is negligible.

4) Buckling - changing the COM of the cavity results in measured forces.  This includes both thermal buckling of wall material caused by rising temperature, as well as pressure induced buckling from expanding interior air if the cavity is hermetically sealed.

EM effects

1) Interaction with Earth's magnetic field.

2) Electrostatic induction - charge buildup on certain sections of the frustum leads to charge induction with local matter, both conductors and insulators.

3) Magnetic induction - the interaction with local conductors.

4) Wire to Wire magnetic force - A net force should only be possible with DC, but vibrations will be caused by AC than can lead to ratcheting (see below).

5) Temporary force caused by changing poynting vector - this will affect experiments run for brief periods of time.

Propellant

1) Ablation/ejection of frustum material

2) Outgassing of sealants - where epoxy or other sealants are used to connect frustum sections, ablation and ejection will be more likely to occur.

3) Thermal jet - leak of heated air.  Will occur in conjunction with buoyancy effects,

Measurement Error

1) Digital equipment is damaged by RF exposure

2) Equipment can't detect the "duty cycle" - If the EMdrive is a pulsed photon rocket, where time averaged net thrust is no better than a photon rocket but individual thrust measurements are, equipment with too low a sampling will not detect the difference.

3) Ratcheting - vibrations lead to a net force, just as a vibrating phone slides across a table.

Specific Setup Issues

1) Spring Force (Iulian)

2) Cooling Fans (Shawyer dynamic rig, Iulian(?))

3) Interaction with permanent magnets (Upcoming Hackday text, Brady et al.(?))


I know that many of these issues I actually read off this forum.  Special thanks to whomever first mentioned the vibrating phone analogy for ratcheting, really helped me understand :)

Offline kml

Specific Setup Issues

1) Spring Force (Iulian)

2) Cooling Fans (Shawyer dynamic rig, Iulian(?))

3) Interaction with permanent magnets (Upcoming Hackday text, Brady et al.(?))

4) Mechanical forces transmitted through feedlines/sensors

5) Net EM forces transmitted through feedlines/power sources.
« Last Edit: 06/04/2015 05:54 PM by kml »

Offline rfmwguy

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2) Electrostatic induction - charge buildup on certain sections of the frustum leads to charge induction with local matter, both conductors and insulators.

Much better stated than my "Electrostatics"...if this is a possibility, it has to be matter "outside" the DUT, conductive or nonconductive...for CoM. At first I suspected Earth's local + or - charge, but the reported horizontal "thrust" measurements kicked that out the window.

Reminds me of a day in a meteorological lecture years ago where I commented "Cloud to ground lightning doesn't concern me, its the ground to human lightning that really freaks me out...." The professor was NOT amused  ;)

Offline wallofwolfstreet

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2) Electrostatic induction - charge buildup on certain sections of the frustum leads to charge induction with local matter, both conductors and insulators.

Much better stated than my "Electrostatics"...if this is a possibility, it has to be matter "outside" the DUT, conductive or nonconductive...for CoM. At first I suspected Earth's local + or - charge, but the reported horizontal "thrust" measurements kicked that out the window.

Reminds me of a day in a meteorological lecture years ago where I commented "Cloud to ground lightning doesn't concern me, its the ground to human lightning that really freaks me out...." The professor was NOT amused  ;)

I was thinking that the chamber walls in the Brady et al. tests are a good candidate for this, or the copper plate that Iulian had placed above his EMdrive.  Can't comment on Shawyer or Yang results.

The force of electrostatic induction is always attractive, because charge on one object causes the opposite charge to move towards it in the second object, leading to force via Coulomb's Law.  This means that so long as the charge buildup was in the same location on the frustum, and the distribution of matter around the frustum is at a relatively constant distance, the electrostatic force would always act in the same direction relative to the frustum (ie. out the large end or out the small end) regardless of orientation.  Hard to differentiate from true thrust in that respect.   

Online Rodal

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What is the rationale for the "Spring Force" artifact?

I thought @frobnicat had disposed of that issue.

Please provide what spring materials you know of that have a substantially different modulus of elasticity E in compression than in tension (this would be useful to experimenters, I guess, to avoid), what is the difference in value for E between compression and tension, and why you think that the spring used by Berca would display a substantial difference in E between tension and compression.

The overwhelming number of materials commonly used as springs have practically the same modulus of Elasticity in tension than in compression.

With deformations large enough, the issue that comes up is not one of bilinearity between tension and compression, but it is one of nonlinearity.  For large deformations spring materials behave with a cubic nonlinearity, but they are still elastic and have same properties in tension and compression.

You would have to reach plasticity (permanent deformation) of a metal to exhibit significant differences between tension and compression.  Most polymers are elastic up to the point of breaking.  If somebody uses a metal spring to the point that it suffers permanent deformation, this should be obvious upon unloading (permanent set). Since metals have extremely high modulus of elasticity, you would need to use very small cross-sectional area metal to measure these very small forces  (but Berca apparently did not use a metal spring), which would mean that to reach plasticity you would have very large spring deformations.  All very unlikely.
« Last Edit: 06/04/2015 06:45 PM by Rodal »

Online Rodal

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"the chamber walls in the Brady et al. tests a"  an issue ?

have we forgotten about the tests that Paul March reported with the EM Drive outside the chamber walls?

Offline Star One

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The Huffington Post gives the EM drive a spin around the photon drive block.

http://m.huffpost.com/us/entry/7489064

Update from hackaday about their EM drive.

https://hackaday.io/project/5596-em-drive/log/18994-cavity-finished
« Last Edit: 06/04/2015 06:47 PM by Star One »

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