Author Topic: EM Drive Developments - related to space flight applications - Thread 3  (Read 1797939 times)

Offline A_M_Swallow

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{snip}
Any comments on something else to monitor?

Microwave leakage
Air currents

The Faraday cage should stop any microwaves but we are looking for something acting as propellant.
A large moving object will move the air around but there may be an unexpected wind. Wind tunnels traditionally used paper streamers.

Offline SeeShells

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Shell, I didn't realize they were both gifs. When I click the big one to enlarge it makes me cross-eyed.

Looks like random bouncing. I don't really see any standing wave pattern to it. The antenna is offset from the middle? In that configuration, you may need to run the simulation longer to develop a standing wave that has more amplitude than the antenna. Once the Q factor takes over in the cavity, the antenna should be a smaller contribution. Since we are looking at such a short slice, and during the turn-on transient, I think what we see has more to do with the antenna than the cavity resonance, IMO.
Todd

Todd: you are 100% correct concerning this pattern.  Ditto for the previous run.  I examined the csv files and arrived at the same conclusion.
The previous runs with the dipole antenna in the middle had established clear TM11 standing wave modes. The last two runs are fluctuating, asymmetric fluctuations due to the antenna being very asymetrically placed. 
Placing the antenna in an asymmetric location in the Meep model (rather than centrally symmetrically located), rather than exciting a TE mode ends up producing very asymmetric fields and a lack of resonance  The Q is thousands of times lower.   There are no standing waves being formed. 

1) No conclusions should be ever be drawn without looking at the NUMERICAL MAGNITUDE of the response.   Runs should not be compared without taking into account that the electric and magnetic fields numerical magnitude patterns are much smaller than others.

2) Anything looking fractal or contour plots that are not smooth indicated noise and very low magnitude.

3) The Meep output for Q should be taken into account.  Q of millions (previous runs) means that the resistivity is way too low in the model.  Q's of thousands with the same model (when it should be millions, due to the unphysically low resisitvity) means lack of resonance.  The physical reality should not be confused with the numerical model.  The present numerical model gives a Q of millions (which is unphysical) when there is resonance,because the Drude model constants being used are tantamount to a superconducting cavity.  If the same Drude model (which is tantamount to superconductivity due to its effective very low resistivity) gives a Q of thousands it means that the cavity is not in resonance, since the Q is thousands of times lower than what it should be.  If people are uncomfortable with Q of millions, this can be addressed by changing the Drude model variables so that the resistivity is increased such that the Q becomes realistic.

Another observation: there has not been a single excitation of a TE mode in any MEEP run for Yang/Shell up to now.

Further exploration is required in order to find out how to excite TE modes using Meep.

Asymmetric location of the antenna just results in very asymmetric fields being excited.
Not quite random bouncing there is a rotational pattern in the direction upwards from the antenna, the EM field ofthe antenna is pushing the modes around the cavity. Q will suffer as modes deform.

I asked aero to add 2 other antennas on the same plane equidistant  around the large plate similar to TT's 3 antennas he is proposing in his frustum. That will should prevent mode shifting and increase Q as well as maintain stable mode shapes.

Shell

Offline TheTraveller

{snip}
Any comments on something else to monitor?

Microwave leakage
Air currents

The Faraday cage should stop any microwaves but we are looking for something acting as propellant.
A large moving object will move the air around but there may be an unexpected wind. Wind tunnels traditionally used paper streamers.

The rotary table will have a transparent plastic side wall surround ring so as to minimise atmo resistance and make atmo resistance as constant as possible.

Good idea. Will place several paper streamers around the table.

The frustum will be totally sealed (both Rf and atmo wise) and operate inside a Faraday Cage as well as a perspex box. External design as the SRP Flight Thruster. Will do microwave leak scan around the frustum end plates, antenna connector and side wall mounted air value and pressure sensor.

Expect the internal frustum pressure, at the end of a run, to be the same as it started. Thus no internal frustum heated N2 escaped to form a hot N2 jet.
« Last Edit: 08/05/2015 11:35 AM by TheTraveller »
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Offline TheTraveller

I asked aero to add 2 other antennas on the same plane equidistant  around the large plate similar to TT's 3 antennas he is proposing in his frustum. That will should prevent mode shifting and increase Q as well as maintain stable mode shapes.

Shell

Good to see you start to understand the enemy is phase distortion between the antenna and the EM waves. Normally antenna designers don't need to handle / design for the antenna's Rf being reflected back and dealing with the out of phase result. Here we have Rf being reflected from both ends back to the antenna and needing to keep the antenna in phase alignment to both waves.
« Last Edit: 08/05/2015 11:33 AM by TheTraveller »
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Offline rfmwguy

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Nice animation shell, would u be able to estimate the Z axis rotational velocity Db to Ds? Assuming they are the same time slice, etc...

Offline Prunesquallor

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During the cordless and totally self contained rotary table EMDrive experiments, the following data will be monitored, data logged and streamed live.

Force generated - calculated
Angular velocity - measured
Angular acceleration - calculated & measured
Forward Rf power - measured
Reflected Rf power - measured
VSWR - calculated
Frequency - measured
Rf amp power consumed - measured
Internal frustum pressure - measured
End plate, side wall and ambient temperature - measured

Any comments on something else to monitor?

Not a measurement per se, but I assume your force calculations will rely on the turntable moment of inertia. Mass and placement of all turntable components should be made available.

Thanks.
« Last Edit: 08/05/2015 12:08 PM by Prunesquallor »
Retired, yet... not

Offline SeeShells

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I asked aero to add 2 other antennas on the same plane equidistant  around the large plate similar to TT's 3 antennas he is proposing in his frustum. That will should prevent mode shifting and increase Q as well as maintain stable mode shapes.

Shell

Good to see you start to understand the enemy is phase distortion between the antenna and the EM waves. Normally antenna designers don't need to handle / design for the antenna's Rf being reflected back and dealing with the out of phase result. Here we have Rf being reflected from both ends back to the antenna and needing to keep the antenna in phase alignment to both waves.
You're so very right.

I wanted to see it myself and verify it with one antenna and even if aero's and IMBFAN's design would produce anything. EagleWorks did the same thing with one antenna in the sidewall and I'm quite sure they ended up distorting modes and decreasing Q.

Watching the animations I was reminded of my 7 grade science class where the teacher took a tuning fork and touched it to a bowl of semi jelled jello, you could see the standing waves and as he tried different tuning forks the patterns would change, funny I still see that analogy.

Shell

Offline A_M_Swallow

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Not a measurement per se, but I assume your force calculations will rely on the turntable moment of inertia. Mass and placement of all turntable components should be made available.

Thanks.

Alternatively use a different source to supply a know force, by measuring the acceleration the moment of inertia can be calculated.

Offline Silversheep2011

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{snip}
Any comments on something else to monitor?

Microwave leakage
Air currents

The Faraday cage should stop any microwaves but we are looking for something acting as propellant.
A large moving object will move the air around but there may be an unexpected wind. Wind tunnels traditionally used paper streamers.

The rotary table will have a transparent plastic side wall surround ring so as to minimise atmo resistance and make atmo resistance as constant as possible.

Good idea. Will place several paper streamers around the table.

The frustum will be totally sealed (both Rf and atmo wise) and operate inside a Faraday Cage as well as a perspex box. External design as the SRP Flight Thruster. Will do microwave leak scan around the frustum end plates, antenna connector and side wall mounted air value and pressure sensor.

Expect the internal frustum pressure, at the end of a run, to be the same as it started. Thus no internal frustum heated N2 escaped to form a hot N2 jet.

I did an enclosed test 1200 x800 high with a model RC helicopter a few years ago at home. Looking for turbulence effects. And found that while streamer's or tufted out wool 7" long works out as being o.k.  It wasn't that good at low speed movements.  more like suited  at about the 0.5mtr/sec and above.

I think you might want to consider with your tuffs or streamers  also add in some smoke 'whiffs' for  really slow movement stuff.

 -here's a link to get you 'thinking'.

http://www.chimneyballoonusa.com/blog/2009/09/compare-and-review-of-smoke-pencils-and-smoke-puffer-sticks-for-air-testing.html

P.S. The Traveller- I'm looking forward to the results, whatever they are! 
 

Offline TheTraveller

During the cordless and totally self contained rotary table EMDrive experiments, the following data will be monitored, data logged and streamed live.

Force generated - calculated
Angular velocity - measured
Angular acceleration - calculated & measured
Forward Rf power - measured
Reflected Rf power - measured
VSWR - calculated
Frequency - measured
Rf amp power consumed - measured
Internal frustum pressure - measured
End plate, side wall and ambient temperature - measured

Any comments on something else to monitor?

Not a measurement per se, but I assume your force calculations will rely on the turntable moment of inertia. Mass and placement of all turntable components should be made available.

Thanks.

The mass centre of all items will be on the same 0.75m radius. Will show the mass of all objects on the table, including the table itself so the resultant Moment of Inertia can be calculated.

The table has a 7,200 pulse per rev (20 pulses per degree of rotation plus 1 pulse pre rev sync) optical track on the bottom outer edge of the table to generate highly accurate real time velocity information.
"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

Watching the animations I was reminded of my 7 grade science class where the teacher took a tuning fork and touched it to a bowl of semi jelled jello, you could see the standing waves and as he tried different tuning forks the patterns would change, funny I still see that analogy.

Shell

Good engineers are VERY visual creatures.
"As for me, I am tormented with an everlasting itch for things remote. I love to sail forbidden seas.
Herman Melville, Moby Dick

Offline OttO

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For SeeShells:
I think I foound in the article below the track of an old silverback... :)

Universal spin-momentum locking of evanescent waves

http://arxiv.org/abs/1504.06361
We notice the striking fact that this coupling factor of
the chiral emitter into the HE11 mode is direction de-
pendent.

Offline TheTraveller

I think you might want to consider with your tuffs or streamers  also add in some smoke 'whiffs' for  really slow movement stuff.

 -here's a link to get you 'thinking'.

http://www.chimneyballoonusa.com/blog/2009/09/compare-and-review-of-smoke-pencils-and-smoke-puffer-sticks-for-air-testing.html

P.S. The Traveller- I'm looking forward to the results, whatever they are!

Old sailors trick.

Use 0.25m long pieces of old cassette tape. Very low mass but high surface area.

What I expect to see is air being thrown outward from the rotating table and being drawn up from the floor and down from the roof to make up for the air being thrown outward.
« Last Edit: 08/05/2015 12:33 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

Online Rodal

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Cullen, Shawyer and Prof Yang are correct, as attached, to use the guide wavelength inside their waveguides (other side of the same coin as group velocity) to calc the end plate reflected Force generation.

Looking at the above-mentioned quotation by Yang you will notice that she mentions this as the introduction to her paper, for historical reasons, and that she does not actually support or much less use this in any of her calculations.   It is in section one of her paper, as a historical introduction, where she clearly states that this is what Roger Shawyer maintains and not her theory:



"Original idea..." "Roger Shawyer..." got it?  It is a historical introduction.  Just like a book about the quantum vacuum could start by mentioning the history of the super-rigid aether which was later proven to be wrong.

Get the difference?

 Tajmar starts his paper by quoting Shawyer's theory but is more up-front: in Tajmar's paper Tajmar makes it plain to distance himself from Shayer's "theory" calling it controversial ("pushing against itself" :)  ):

Quote from: Tajmar
It must be noted that Shawyers analysis and claims are highly controversial (e.g. Ref. 9) as this would obviously violate the conservation of momentum (pushing against itself) following his theory. Aside from the theoretical concept, most interesting are the experimental claims that have been published to date

Yang is more diplomatic, rather than saying that Shawyer's theory is controversial, she proceeds to develop her own theory: Yang never uses the group velocity in her calculations.  Yang uses a Finite Element formulation that dispenses with Shaweyr's theory.  Yang effectively throws Shawyer's theory to the dustbin: observe how Shawyer claims that there is no pressure on the sidewalls, while Yang shows that Shawyer is wrong as she calculates the pressure on the sidewalls and shows how important the pressure on the sidewalls is.

So far everybody has distanced themselves from Shaywer's "theory"  McCulloch has made it plain,  Tajmar also has distanced himself,  Yang is more diplomatic.  One has to understand Yang's formulation to understand that Yang also distances herself and rejects Shaywer's theory.  Yang is subtle: instead of saying how wrong Shawyer is with words, Yang uses equations.  One has to read Yang's paper beyond section one, and understand Yang's equations in order to understand how Yang rejects Shawyer's theory.

 
« Last Edit: 08/05/2015 01:31 PM by Rodal »

Offline SeeShells

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Nice animation shell, would u be able to estimate the Z axis rotational velocity Db to Ds? Assuming they are the same time slice, etc...

Rough guesstimate looking at the small end hz just to make sure I'm seeing this right.

Looking at the Small end rotational movement (hz.t00.png-hz.t13.png) it looks pretty close to 270 degrees of rotation by following the modes circular pattern start and stop. The displayed run of 14 slices or equals ~20 degree shift per image.  For one 360 degree rotation that would be 360/20 or 18 time slice images.

That number is very close to what areo reported of 32 cycles @ 2.45E+009 but he only said he sliced out 1/10 of each cycle from 30.7 to 32 which is only 1.3 cycles.

So it looks like for the duration of 1.3 cycles in the small end the pattern rotated 270 degrees and this doesn't make sense.

Looking at the Center Y it looks like I get a shift every 1/2 cycle which makes more sense @2.45 GHz  = 4.0816326530612E-10 / 2 =  2.0408163265306E-10 seconds

Meep data description file.
https://lh3.googleusercontent.com/vHkbiKjDvChfkZ9bGm2Dv8MDCZOw2cx6zhoqL_QGsgk-CtQrXPolxIQa9lOR68vBEo7ngw=s190

Provide the following data uploaded to Google Drive for distribution.
<snip>
Run length - 32 full cycles
Generate files for field components Ex, Ey, Ez, Hx, Hy, Hz
Time slices output for each field component:
    every 1/10-th cycle from 30.7 cycles to 32 cycles (end of run)
 

Offline SeeShells

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For SeeShells:
I think I foound in the article below the track of an old silverback... :)

Universal spin-momentum locking of evanescent waves

http://arxiv.org/abs/1504.06361
We notice the striking fact that this coupling factor of
the chiral emitter into the HE11 mode is direction de-
pendent.


That's interesting. I was laying out one one the frustums in cad the other day and I wondered at the time if the Golden ratio had any bearing in the design and pulled my copy of The Golden Ratio by Mario Livio from my book case to re-read. Could be another brick in the wall.
Quote...
This circular TIR condition occurs if and only if the ratio of permittivities of the two dielectric media exceeds the golden ratio.

Thanks,
Shell

Offline Flyby

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That's interesting. I was laying out one one the frustums in cad the other day and I wondered at the time if the Golden ratio had any bearing in the design and pulled my copy of The Golden Ratio by Mario Livio from my book case to re-read. Could be another brick in the wall.
Quote...
This circular TIR condition occurs if and only if the ratio of permittivities of the two dielectric media exceeds the golden ratio.

Funny you say that , Shell, it has crossed my mind also.
As architect student (long ago) , I've encountered the golden ratio many and multiple times. From man-build constructions to beautiful examples in nature.
I do believe the golden ration falls back on a fundamental principle in physics.
It's frequent occurrence in our universe can't be a mere coincidence, nor do i consider it a divine sign...
So...there must be more behind it...

http://www.sciencedaily.com/releases/2010/01/100107143909.htm

A Nobel price for the one that finds it.. ;)

Offline WarpTech

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Shell, I didn't realize they were both gifs. When I click the big one to enlarge it makes me cross-eyed.

Looks like random bouncing. I don't really see any standing wave pattern to it. The antenna is offset from the middle? In that configuration, you may need to run the simulation longer to develop a standing wave that has more amplitude than the antenna. Once the Q factor takes over in the cavity, the antenna should be a smaller contribution. Since we are looking at such a short slice, and during the turn-on transient, I think what we see has more to do with the antenna than the cavity resonance, IMO.
Todd

Todd: you are 100% correct concerning this pattern.  Ditto for the previous run.  I examined the csv files and arrived at the same conclusion.
The previous runs with the dipole antenna in the middle had established clear TM11 standing wave modes. The last two runs are fluctuating, asymmetric fluctuations due to the antenna being very asymetrically placed. 
Placing the antenna in an asymmetric location in the Meep model (rather than centrally symmetrically located), rather than exciting a TE mode ends up producing very asymmetric fields and a lack of resonance  The Q is thousands of times lower.   There are no standing waves being formed. 

1) No conclusions should be ever be drawn without looking at the NUMERICAL MAGNITUDE of the response.   Runs should not be compared without taking into account that the electric and magnetic fields numerical magnitude patterns are much smaller than others.

2) Anything looking fractal or contour plots that are not smooth indicated noise and very low magnitude.

3) The Meep output for Q should be taken into account.  Q of millions (previous runs) means that the resistivity is way too low in the model.  Q's of thousands with the same model (when it should be millions, due to the unphysically low resisitvity) means lack of resonance.  The physical reality should not be confused with the numerical model.  The present numerical model gives a Q of millions (which is unphysical) when there is resonance,because the Drude model constants being used are tantamount to a superconducting cavity.  If the same Drude model (which is tantamount to superconductivity due to its effective very low resistivity) gives a Q of thousands it means that the cavity is not in resonance, since the Q is thousands of times lower than what it should be.  If people are uncomfortable with Q of millions, this can be addressed by changing the Drude model variables so that the resistivity is increased such that the Q becomes realistic.

Another observation: there has not been a single excitation of a TE mode in any MEEP run for Yang/Shell up to now.

Further exploration is required in order to find out how to excite TE modes using Meep.

Asymmetric location of the antenna just results in very asymmetric fields being excited.
Not quite random bouncing there is a rotational pattern in the direction upwards from the antenna, the EM field ofthe antenna is pushing the modes around the cavity. Q will suffer as modes deform.

I asked aero to add 2 other antennas on the same plane equidistant  around the large plate similar to TT's 3 antennas he is proposing in his frustum. That will should prevent mode shifting and increase Q as well as maintain stable mode shapes.

Shell

I doubt it will fix it. The "rotation" looks more like simply reflections bouncing side to side, around a circle. 3 antenna will just have 3 overlapping sets of random reflections. We shall see...
Todd

Online Rodal

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I doubt it will fix it. The "rotation" looks more like simply reflections bouncing side to side, around a circle. 3 antenna will just have 3 overlapping sets of random reflections. We shall see...
Todd
To solve it, it is necessary to understand the fundamental mode shape one wants to excite: how the amplitude of the mode shape is supposed to vary along the intrinsic spherical coordinate system (certainly not the extrinsic Cartesian coordinate system).  The variation is governed by Associated Legendre Functions in the spherical polar angle, Spherical Bessel in the spherical radii, and Harmonic in the spherical azimuthal angle. 

The Cartesian system, and anything based on it is unnatural to the physical problem.
« Last Edit: 08/05/2015 02:18 PM by Rodal »

Offline SeeShells

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That's interesting. I was laying out one one the frustums in cad the other day and I wondered at the time if the Golden ratio had any bearing in the design and pulled my copy of The Golden Ratio by Mario Livio from my book case to re-read. Could be another brick in the wall.
Quote...
This circular TIR condition occurs if and only if the ratio of permittivities of the two dielectric media exceeds the golden ratio.

Funny you say that , Shell, it has crossed my mind also.
As architect student (long ago) , I've encountered the golden ratio many and multiple times. From man-build constructions to beautiful examples in nature.
I do believe the golden ration falls back on a fundamental principle in physics.
It's frequent occurrence in our universe can't be a mere coincidence, nor do i consider it a divine sign...
So...there must be more behind it...

http://www.sciencedaily.com/releases/2010/01/100107143909.htm

A Nobel price for the one that finds it.. ;)
Sometimes I feel so so brain dead when I get on here, there are some absolutely incredible  sharp people here. But that said I've always loved the golden ratio it is one of the most beautiful numbers I've seen and it seems to permeate everything around us and to have found it in nanoscale symmetry hidden in solid state matter doesn't phase me one bit. So I was fooling around with the ratio 1.61803398875 in the design of the frustum to see what it showed. :) still playing with it.

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