Author Topic: EM Drive Developments - related to space flight applications - Thread 3  (Read 1800445 times)

Offline TheTraveller

... She never mentions a dielectric. So it seems no dielectric was used by Prof Yang.
Wrong.  Yang explicitly mentions a dielectric in her original 2010 paper in Chinese.

Perhaps you did not read this post:  http://forum.nasaspaceflight.com/index.php?topic=37642.msg1411922#msg1411922, so I will make these points again one by one, and be more direct this time as to where you make mistakes:


1) The equation you posted for Q is wrong, it is not the equation that Yang used.   The equation you posted for Q does not make any sense.  It never appears in Yang's original 2010 paper in Chinese.
2) You posted an equation for Q that instead came from a very bad translation in Shawyer's website instead of coming from her original 2010 paper in Chinese. 
3) The original paper in Chinese by Yang has the correct equation for Q.
4) In the original paper in Chinese by Yang she uses tnδ and instead of tnd.  tnδ means tangent delta (loss tangent) which is the material property for a dielectric loss, which reduces the Q.
5) In the original 2010 paper in Chinese by Yang she explicitly writes: "dielectric losses" instead of the badly translated "electric losses" that appears in the bad translation

I don't know whether Yang did use or did not use dielectrics in any of her experiments, but what is undeniable from reading her 2010 paper in Chinese is that she clearly mentions dielectric losses explicitly and furthermore she goes further: she uses an equation for Q that takes into account dielectric losses.  Why would Yang use an equation for Q that takes into account dielectric losses if she never used dielectrics or planned to use dielectric inserts?

Stop nit picking. I posted the equation from the translated paper. If is wrong, so be it. A point to you for discovering the bad translation. End of story.

As for the use or not of a dielectric, please point to one statement from Prof Yang that she used a dielectric in the frustum used to record the Forces generated?

Just maybe Prof Yang did, in the early stages, test with a dielectric but then confirmed Shawyer was correct and discarded it for the rest of her tests.

Shawyer did say that both he and Prof Yang discarded using dielectrics a long time ago. Which would suggest Prof Yang may have done testing with and without dielectrics and came to the same conclusion as Shawyer that they reduced generated Force.

Really don't know where you are going here?
"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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This is the statement:

腔体内充填的电介质损耗

in:
Applying Method of Reference 2 to Effectively Calculating Performance of Microwave Radiation Thruster
Yang Juan,Yang Le,Zhu Yu,Ma Nan
Journal of Northwestern Polytechnical University, Dec. 2010, V01.28 No.6, page 810

___________________________________

PS: I'm glad that the NSF forum accepts Chinese characters! That makes this answer simple.  Awesome. :)
« Last Edit: 08/01/2015 07:39 AM by Rodal »

Offline TheTraveller

Doing impedance matching

All frustums need to be impedance matched to the Rf source. Doesn't matter if the Rf source is Magnetron or Rf amp.

Typical way to do that is with a 2 or 3 stub tuner.

Here is the 3 stub coax tuner I will be using between my Rf amp and the frustum.

Waveguide mounted 2 and 3 stub tuners are also available. Of course to use them your magnetron needs to couple Rf energy to the frustum via a waveguide.

I have no idea how to impedance match a direct coupled magnetron and frustum. Anybody know how to do this?

As far as I can find out, only Iulian used a direct couple and his data is highly questionable.

Shawyer in his 1st Experimental EMDrive, 2nd Demonstrator EMDrive and Tajmar's EMDrive used a waveguide between the frustum and the magnetron. I know in the Demonstrator waveguide there was a 2 stub impedance matching setup. I assume there was that capability in the Experimental and Tajmar EMDrives.

So DIY EMDrive builders you need to design in a way to tune the impedance match between your frustum and the Rf source.
"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

This is the statement:

腔体内充填的电介质损耗

in:
Applying Method of Reference 2 to Effectively Calculating Performance of Microwave Radiation Thruster
Yang Juan,Yang Le,Zhu Yu,Ma Nan
Journal of Northwestern Polytechnical University, Dec. 2010, V01.28 No.6, page 810

___________________________________

PS: I'm glad that the NSF forum accepts Chinese characters! That makes this answer simple.  Awesome. :)

Please stop picking at the edges.

The translation is "Dielectric loss cavity filling".

The question I asked you was, Where is it stated the frustum used to measure the Force generated, as reported by Prof Yang, had a dielectric inside? So far you have not answered that question.
« Last Edit: 08/01/2015 07:45 AM by TheTraveller »
"As for me, I am tormented with an everlasting itch for things remote. I love to sail forbidden seas.”
Herman Melville, Moby Dick

Offline arc

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If I knew that...I'd have better answers!
And if we knew more we would have a GUT down pat. ;)
I had a friend ask me today if it was even worth it, you know exploring the solar system because we had probes sent to all the planets and not much more needed to be done. The money could be spent here on earth feeding the hungry masses.
I sent him this.
http://www.space.com/30074-trillion-dollar-asteroid-2011-uw158-earth-flyby.html

perhaps just one of these....   

« Last Edit: 08/01/2015 09:35 AM by arc »

Offline deltaMass

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The main thing I'd like to know about Yang is whether anybody can verify her experimental data at her facility. Neutral parties, I mean.

Offline Silversheep2011

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rfmwguy.

I'm thinking replace the magnetron [see attachment below looks the same] with a RF transistor as used here

http://www.zdnet.com/article/freescales-radio-frequency-oven-the-end-of-the-microwave/

maybe it runs with less heat loss?
and runs cleaner r.f. waves
http://www.freescale.com/webapp/video_vault/videoSummary.sp?code=RF-SAGE-VIDEO

 see 2.37

They still require a heat sink. 3.7 deg. C/Watt is a lot of heat. These are also only good for about 200 to 400 mW per transistor, if you've got a good heat sink. If you want to get back up to 400W, you will need to parallel about a dozen of them on a well designed PC board, that is thermally conductive to the heatsink. At these frequencies, I have no idea how you would do that, or what proper design criteria are necessary for a microwave amplifier of sufficient power.
Todd
I take issue with your use of the arithmetic division operator.

Nick picking again...  oC/W.
Not that - that you say you need "about a dozen" 400 mW transistors to get 400 Watts.

Mr "deltamass" you might like this quote from

 said Mark Murphy, director of marketing, RF power product line, NXP Semiconductors. “Over the last 10 years, engineers exploring the ways to harness RF energy have had to be content using brute force magnetrons with extremely limited or next to no control – with absolute power level the only parameter they could adjust for industrial, scientific and medical applications. With our new dedicated 2.45-GHz ISM portfolio, we’re providing solid-state RF power transistors that have been optimized for this important frequency band, 
said Mark Murphy, director of marketing, RF power product line, NXP Semiconductors. “Over the last 10 years, engineers exploring the ways to harness RF energy have had to be content using brute force magnetrons with extremely limited or next to no control – with absolute power level the only parameter they could adjust for industrial, scientific and medical applications. With our new dedicated 2.45-GHz ISM portfolio, we’re providing solid-state RF power transistors that have been optimized for this important frequency band,

It might mean that this offers extra "tunabilty " that our noble experimenter's maybe are  needing...

I also think you made a "good" comment further back about eliminating 'steam' as a possible error source needing to be eliminated during experimentation.   
1 part liquid H˛O can expand up to 1000 parts H˛O steam is what I was taught...
could be lurking in many hidden sources.   
could be helpful in explain a few anomalies
http://www.nxp.com/news/press-releases/2013/06/is-solid-state-rf-the-next-energy-source.html

also enjoy the little video link at bottom LH of that page.
Me I want those EM 'sparkplugs' in my car 0:45
or how about adapting that plasma light to  a plasma drive!
0:58

Offline X_RaY

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@SeeShells and @Rodal,
The data you are referring to was something I generated after reading a post/paper by Dr. Rodal in which he discussed extending the Brady frustum, using the same big end diameter and the same taper angle, but extending until the small end diameter equalled 25% of the big end diameter. The views posted are for the start of the cavity, power on until some cycles later. We remarked at the time about the changing range of the signal causing color changes, but no one realized that I had discovered the first step in inventing the "flashy light thingee" used by the Men in Black.

I have used time today to re-run that model generating what has become rather standard upload data, both csv files and png views, here
:

https://drive.google.com/folderview?id=0B1XizxEfB23tfkZVbi1MY2RQZmVkeEVHUmVfQkc3UEdlVkdOVXZENmFYbmg4czJUd1lqcDg&usp=sharing

Read the data request file, where I blamed Rodal for asking for the data. I copied some data from my meep run log into the file giving basic cavity and run information. I did not use run logs back in mid June but it is the same model so today's run log data should be the same as was ran back in  June. I don't recall where the 2.14 GHz center drive frequency number came from, perhaps it was Harminv.

In any case, I hope this data tells us something, and Dr. Rodal, the complete set of 14 time slice csv files are there so you now have the data to calculate stresses. I'd be interested in seeing the result. Looks to me like zero force on the small end, but appearances can be deceiving.
Nice run and a wonderful example of how the antenna works
« Last Edit: 08/01/2015 11:02 AM by X_RaY »

Offline X_RaY

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This is the statement:

腔体内充填的电介质损耗

in:
Applying Method of Reference 2 to Effectively Calculating Performance of Microwave Radiation Thruster
Yang Juan,Yang Le,Zhu Yu,Ma Nan
Journal of Northwestern Polytechnical University, Dec. 2010, V01.28 No.6, page 810

___________________________________

PS: I'm glad that the NSF forum accepts Chinese characters! That makes this answer simple.  Awesome. :)
LOL  ;D good point
Google translation: 腔体内充填的电介质损耗=Dielectric loss cavity filling
« Last Edit: 08/01/2015 12:55 PM by X_RaY »

Offline rfmwguy

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@rfmwguy since it appears you can't run continuously for a prolonged period without reaching a critical heat regime, what's the plan?

Are you going to implement a cooling system so you can run continuously, or used a reduced power level that involves the magnetron cycling off and on? If the later, how would you untangle the ramp-up, ramp-down seen in previous experiments from the magnetron cycles? It would see, to be difficult under those circumstances to have a very clean relationship between system on/off and measured thrust.
I suspect radiation "pooling" is the result of the one machine screw getting overheated. I'll address that with some tighter shielding. Regarding the core temp of the mag, I will relocate the injection point to see if I can achieve lower temp. The higher core temp may indicate standing wave matching issues. We'll see. Thanks for the comments.

Offline rfmwguy

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After seeing that vid I'm adding another artifact candidate - steam jet.
I agree, that's why I want to do a lot of thermal testing of hotspots. The machine screw head was way hotter than surrounding metal. I suspect some rf leakage between copper clad end plates. Simple fix I'll mess with over the weekend. Thermal issues need to be addressed well ahead of torsion or balance testing imho.

Use a heatsink that has radial fins, so orientation doesn't matter. As it is now, the fins are in the wrong direction. The fins are flat with the openings on the sides. The opening should be up and down, so convention will cool it, pulling cool air in from the bottom. The airflow is blocked.

Granted, this will never work in a vacuum chamber without liquid cooling or a very large mass to dump heat into.
Todd
Good eye warpy, the fins are aligned horizontally. I could get a couple of microprocessor heat sinks and put on the sides...aligning the fins vertically. Thanks!

Offline rfmwguy

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Just a random thought @rfmwguy.

I know you don't want to blow air over the fins, but would you be able to calibrate the force balance if you used your wife's vacuum sweeper hose to suck air across them? Maybe a longer hose so it exhausted outside? Maybe an inlet of some sort to channel the moving  air to minimize stray air currents?

Maybe a liquid cooling loop.  ;D

The lag in the temperature readings after turn-off seemed to indicate that the center of the magnetron got much hotter than the fins where you were measuring temperature.
Yes, the core (tube) is reflective and not as easy to get a good reading with the IR gun. Nope, no sloshing coolant for me. I'll do my best to have passive cooling so as not to introduce any more variables. As I noticed, this thing has to be thermally managed better to avoid thermal currents.

Offline rfmwguy

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Actually I got the impression from the vid that the heat capacity of the magnetron is quite low - it lost heat very rapidly after turn off. Oddly perhaps, the same could not be said of the frustum.

Or perhaps these observations are due to vid editing messing with the observed timeline?
It was about 1 minute clipped out as I took the cam off the tripod. Next time, I'll just let it run...you are correct, that is the best way.

Offline rfmwguy

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rfmwguy.

I'm thinking replace the magnetron [see attachment below looks the same] with a RF transistor as used here

http://www.zdnet.com/article/freescales-radio-frequency-oven-the-end-of-the-microwave/

maybe it runs with less heat loss?
and runs cleaner r.f. waves
http://www.freescale.com/webapp/video_vault/videoSummary.sp?code=RF-SAGE-VIDEO

 see 2.37
Thanks, its all about the money...which I try to conserve while my wife puts up with my weird interests ;)

Offline X_RaY

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Doing impedance matching

All frustums need to be impedance matched to the Rf source. Doesn't matter if the Rf source is Magnetron or Rf amp.

Typical way to do that is with a 2 or 3 stub tuner.

Here is the 3 stub coax tuner I will be using between my Rf amp and the frustum.

Waveguide mounted 2 and 3 stub tuners are also available. Of course to use them your magnetron needs to couple Rf energy to the frustum via a waveguide.

I have no idea how to impedance match a direct coupled magnetron and frustum. Anybody know how to do this?

As far as I can find out, only Iulian used a direct couple and his data is highly questionable.

Shawyer in his 1st Experimental EMDrive, 2nd Demonstrator EMDrive and Tajmar's EMDrive used a waveguide between the frustum and the magnetron. I know in the Demonstrator waveguide there was a 2 stub impedance matching setup. I assume there was that capability in the Experimental and Tajmar EMDrives.

So DIY EMDrive builders you need to design in a way to tune the impedance match between your frustum and the Rf source.
You can do this by using stubs/bolts directly into the frustum(near the antenna for example), but well you have to measure for while tuning.

Picture form: http://home.comcast.net/~nwilson343/transitions.html
« Last Edit: 08/01/2015 01:19 PM by X_RaY »

Online flux_capacitor

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{snip}

I continue on this internal height of 68.6 mm according to Tajmar, being non-resonant.

One thing for sure: the height cannot be twice the height as noted in the paper, as some suggested. It is not the same "error of a factor two" as the diameters in the first paper being actually radii. Evidence below. On the left, height of 68.6 mm. On the right, height of 68.6 x 2 = 137.2 mm.



For comparison, picture of Tajmar's cavity:



The "twice height" is clearly an absurd ratio and we can rule that out.

Keep in mind the diagram above is based on internal dimensions and the external aspect of the cavity cannot be the same because :
- copper walls have a thickness of 3 mm according to the updated paper.
- the end plates are spherical
- and most importantly, the external shape of the cavity is apparently higher because the small end plate is axially recessed within, via the tuning screw.

For this reason the external height is in reality longer.

Then, let's play with the WR340 waveguide. We know it's "too large to fit" Tajmar's length of 68.6 mm.

Mechanical drawing of a WR340 waveguide flange cross section:



Internal waveguide length = 86,36 mm.
So the slope side of the cavity could not have a length below this value.

In the picture of Tajmar's cavity above, we can observe the side of the internal waveguide (the custom part that is hard soldered to the cavity using silver) extends among almost all the wall length of the cavity, if we take into account the spherical upper end plate is recessed downwards so the real internal height is shorter than the object we're looking at from the outside.

So I modeled a WR340 waveguide in SketchUp and played a bit with it. Then one thing surprised me:
When we lift the small end from the initial value of 68.6 mm upper, to the value of 86.6 mm, the side entrance of the WR340 waveguide (86,36 mm) now fits the cavity length. What a coincidence!
Well, could the height of 68.6 mm be a typo inverting two numbers and the author really wanted to write 86.6 mm?

@Rodal, to prove/disprove this hypothesis, can you try to find if a resonance at any mode exists with those numbers:
- big end diameter = 0.1082 m
- small end diameter = 0.077 m
- internal height = 0.0866 m
with spherical ends?

Maybe this is totally wrong, but it would be cool if it matched ;)
« Last Edit: 08/01/2015 04:13 PM by flux_capacitor »

Online Rodal

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@SeeShells and @Rodal,
The data you are referring to was something I generated after reading a post/paper by Dr. Rodal in which he discussed extending the Brady frustum, using the same big end diameter and the same taper angle, but extending until the small end diameter equalled 25% of the big end diameter. The views posted are for the start of the cavity, power on until some cycles later. We remarked at the time about the changing range of the signal causing color changes, but no one realized that I had discovered the first step in inventing the "flashy light thingee" used by the Men in Black.

I have used time today to re-run that model generating what has become rather standard upload data, both csv files and png views, here:

https://drive.google.com/folderview?id=0B1XizxEfB23tfkZVbi1MY2RQZmVkeEVHUmVfQkc3UEdlVkdOVXZENmFYbmg4czJUd1lqcDg&usp=sharing

Read the data request file, where I blamed Rodal for asking for the data. I copied some data from my meep run log into the file giving basic cavity and run information. I did not use run logs back in mid June but it is the same model so today's run log data should be the same as was ran back in  June. I don't recall where the 2.14 GHz center drive frequency number came from, perhaps it was Harminv.

In any case, I hope this data tells us something, and Dr. Rodal, the complete set of 14 time slice csv files are there so you now have the data to calculate stresses. I'd be interested in seeing the result. Looks to me like zero force on the small end, but appearances can be deceiving.

A brief heads up on this run (NASA Brady et.al. geometry extended to near the apex of the cone):

1) Non-symmetric placement of antenna, very offset from middle

2) Amplitude of response is very low: not a good resonance.  It shows fractal numerical artifacts due to very low amplitude.

3) Forces at both ends are very low. Stress distribution at big end very low and very asymmetric.  Force at small end close to zero.  This is something important we have learnt from this:  extending the cone can eliminate the force at the small end. 

Suggestion: may need to run again, at an excitation frequency for which we know (from other calculations) that there is a good resonant response and with an antenna located on the axis axi-symmetry. 

If run again, it may be better to do it based on Yang/Shell geometry extended to near the apex of the cone, to model the geometry she intends to test.
« Last Edit: 08/01/2015 02:37 PM by Rodal »

Online SeeShells

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The main thing I'd like to know about Yang is whether anybody can verify her experimental data at her facility. Neutral parties, I mean.
I'd love to be the proverbial fly on the wall, my luck I'd buzz to close to the giant bug zapper called a frustum.

I'm hoping that the frustum I'm putting together matches the best guess of the group here. Nobody has taken the bull by the horns to try to at least validate their claims by building something close to their design. I honestly believe it needs to be addressed and I'm trying to do so as best as I can. So criticism is welcome.

TT did you ever run Yang's model in your spreadsheet as reported in the Wiki site? What did you see, inquiring minds want to know.

Shell

Offline rfmwguy

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@SeeShells and @Rodal,
The data you are referring to was something I generated after reading a post/paper by Dr. Rodal in which he discussed extending the Brady frustum, using the same big end diameter and the same taper angle, but extending until the small end diameter equalled 25% of the big end diameter. The views posted are for the start of the cavity, power on until some cycles later. We remarked at the time about the changing range of the signal causing color changes, but no one realized that I had discovered the first step in inventing the "flashy light thingee" used by the Men in Black.

I have used time today to re-run that model generating what has become rather standard upload data, both csv files and png views, here:

https://drive.google.com/folderview?id=0B1XizxEfB23tfkZVbi1MY2RQZmVkeEVHUmVfQkc3UEdlVkdOVXZENmFYbmg4czJUd1lqcDg&usp=sharing

Read the data request file, where I blamed Rodal for asking for the data. I copied some data from my meep run log into the file giving basic cavity and run information. I did not use run logs back in mid June but it is the same model so today's run log data should be the same as was ran back in  June. I don't recall where the 2.14 GHz center drive frequency number came from, perhaps it was Harminv.

In any case, I hope this data tells us something, and Dr. Rodal, the complete set of 14 time slice csv files are there so you now have the data to calculate stresses. I'd be interested in seeing the result. Looks to me like zero force on the small end, but appearances can be deceiving.

A short heads up on this run (NASA Brady et.al. geometry extended to near the apex of the cone):

1) Non-symmetric placement of antenna, very offset from middle

2) Amplitude of response is very low: not a good resonance.  It shows fractal numerical artifacts due to very low amplitude.

3) Forces at both ends are very low.  Force at small end close to zero.  Stress distribution at big end very low and very asymmetric.

Suggestion: may need to run again, at an excitation frequency for which we know (from other calculations) that there is a good resonant response and with an antenna located on the axis axi-symmetry. 

If run again, it may be better to do it based on Yang/Shell geometry extended to near the apex of the cone, to model the geometry she intends to test.
I have almost the same insertion geometry as them except have a monopole rather than a loop. I think my temp tests are confirming a bad match at this locale. Will know more this weekend.

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@SeeShells and @Rodal,
The data you are referring to was something I generated after reading a post/paper by Dr. Rodal in which he discussed extending the Brady frustum, using the same big end diameter and the same taper angle, but extending until the small end diameter equalled 25% of the big end diameter. The views posted are for the start of the cavity, power on until some cycles later. We remarked at the time about the changing range of the signal causing color changes, but no one realized that I had discovered the first step in inventing the "flashy light thingee" used by the Men in Black.

I have used time today to re-run that model generating what has become rather standard upload data, both csv files and png views, here:

https://drive.google.com/folderview?id=0B1XizxEfB23tfkZVbi1MY2RQZmVkeEVHUmVfQkc3UEdlVkdOVXZENmFYbmg4czJUd1lqcDg&usp=sharing

Read the data request file, where I blamed Rodal for asking for the data. I copied some data from my meep run log into the file giving basic cavity and run information. I did not use run logs back in mid June but it is the same model so today's run log data should be the same as was ran back in  June. I don't recall where the 2.14 GHz center drive frequency number came from, perhaps it was Harminv.

In any case, I hope this data tells us something, and Dr. Rodal, the complete set of 14 time slice csv files are there so you now have the data to calculate stresses. I'd be interested in seeing the result. Looks to me like zero force on the small end, but appearances can be deceiving.

A short heads up on this run (NASA Brady et.al. geometry extended to near the apex of the cone):

1) Non-symmetric placement of antenna, very offset from middle

2) Amplitude of response is very low: not a good resonance.  It shows fractal numerical artifacts due to very low amplitude.

3) Forces at both ends are very low.  Force at small end close to zero.  Stress distribution at big end very low and very asymmetric.

Suggestion: may need to run again, at an excitation frequency for which we know (from other calculations) that there is a good resonant response and with an antenna located on the axis axi-symmetry. 

If run again, it may be better to do it based on Yang/Shell geometry extended to near the apex of the cone, to model the geometry she intends to test.
Thank you, it would be quite nice to see that run.
Shell

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