Author Topic: EM Drive Developments - related to space flight applications - Thread 3  (Read 1801677 times)

Online Flyby

  • Full Member
  • ***
  • Posts: 382
  • Belgium
  • Liked: 447
  • Likes Given: 47

(The cone half angle is the angle between the lateral and the perpendicular to the base, not the angle between the lateral and the base)


Well, I do not have a scientific/mathematical background, nor is English my first or even my second language.
If you combine the 2, maybe you'll understand it is not always so easy for me to grasp what you mean...
I'm just not used to decipher mathematical definitions for rather simple things... ;)

No offense taken tough... everybody has his own work environment and the specific language that comes with it...
I'm actually learning a lot from following these discussions...

@Warptech

However, with the longer cylinder-like frustum, her half-angle is so small that extrapolating from the Impedance diagrams on Zeng and Fan, the part of the impedance curve and slope that cylinder is working on is about the same as it is for the other designs with more angle and shorter length. In other words, although her k*r value is in the 30's, the relative impedance shift is in the same ball park as the shorter designs with a larger angle. It may be that having less angle allows it to reach a much higher Q, like a cylinder but the shift in Z is still there to produce thrust.

Todd

 A while ago TT mentioned the cylindrical top and bottom parts (14.4% and 16.6%).
He believed it to be Yang's way to enhance the Q of the cavity. Fact is that we have a combined shape here, where the real internal frustum shape is only 69%  (100-14.4-16.6) of the total length and a cylindrical shape with an internal length of 100%

However, I'll leave it to you guys to figure out how you need to calculate that. That's way out of my knowledge zone...
« Last Edit: 08/01/2015 04:06 PM by Flyby »

Online Rodal

  • Senior Member
  • *****
  • Posts: 5838
  • USA
  • Liked: 5919
  • Likes Given: 5259
...

However, with the longer cylinder-like frustum, her half-angle is so small that extrapolating from the Impedance diagrams on Zeng and Fan, the part of the impedance curve and slope that cylinder is working on is about the same as it is for the other designs with more angle and shorter length. In other words, although her k*r value is in the 30's, the relative impedance shift is in the same ball park as the shorter designs with a larger angle. It may be that having less angle allows it to reach a much higher Q, like a cylinder but the shift in Z is still there to produce thrust.

@TT, if you look at the impedance graphs in Zeng and Fan, you can estimate what the impedance is as the distance k*r from the apex of the cone. That should eliminate the guessing.
Todd

Yes hundreds of pages ago, this Yang geometry was deemed plausible.  Now hundreds of pages later and with weeks of further analysis this Yang geometry does NOT make sense.  We already discussed with you and I thought we had settled that the most important parameter is k r.   k r for Yang Shell is ridiculous:  it is much further from the apex than any other EM Drive. 

I am also the one that bothered to calculate the spherical radii r1 and r2 and the cone angles for all the EM Drives int the Wiki

Take a gander at r1 (the smaller spherical radius) for all the EM Drives in the wiki and compare them.  The one for Yang is off the charts, much further away from the apex.
« Last Edit: 08/01/2015 04:06 PM by Rodal »

Offline ThereIWas3

  • Full Member
  • ****
  • Posts: 612
  • Liked: 260
  • Likes Given: 212
I notice that Shawyer used a larger half-angle than any of the other experimenters, and also has the most experience doing this.  I wonder why people do not, as a starting point, attempt to exactly replicate his experiments.
"If you want to build a ship, don’t drum up people to collect wood and don’t assign them tasks and work, but rather teach them to long for the endless immensity of the sea" - Antoine de Saint-Exupéry

Online Rodal

  • Senior Member
  • *****
  • Posts: 5838
  • USA
  • Liked: 5919
  • Likes Given: 5259
I notice that Shawyer used a larger half-angle than any of the other experimenters, and also has the most experience doing this.  I wonder why people do not, as a starting point, attempt to exactly replicate his experiments.

You got it.  Not just that, but also notice that Shawyer has been increasing the cone angle as time goes by.  For his superconducting design the cone half angle is much greater.


That's why I bothered to calculate the cone half-angle and the spherical radii and put that information in the wiki.

The answer to your question is:

1) Shawyer never gave complete information on his geometrical dimensions.

2) It is very hard work to estimate these dimensions.  It is very hard work to estimate Yang's dimensions, Shawyer's dimensions. 

3) The only one that gave accurate internal dimensions was Paul March from NASA.  (Tajmar gave wrong dimensions, the others no complete information on their dimensions). Iulian Berca and Mulletron replicated the exact dimension of NASA.  Rfmwguy exactly replicates the diameters of NASA with a small change in length to be able to resonate at 2.45GHz
« Last Edit: 08/01/2015 04:26 PM by Rodal »

Offline WarpTech

  • Full Member
  • ****
  • Posts: 1228
  • Do it!
  • Vista, CA
  • Liked: 1295
  • Likes Given: 1749
...

However, with the longer cylinder-like frustum, her half-angle is so small that extrapolating from the Impedance diagrams on Zeng and Fan, the part of the impedance curve and slope that cylinder is working on is about the same as it is for the other designs with more angle and shorter length. In other words, although her k*r value is in the 30's, the relative impedance shift is in the same ball park as the shorter designs with a larger angle. It may be that having less angle allows it to reach a much higher Q, like a cylinder but the shift in Z is still there to produce thrust.

@TT, if you look at the impedance graphs in Zeng and Fan, you can estimate what the impedance is as the distance k*r from the apex of the cone. That should eliminate the guessing.
Todd

Yes hundreds of pages ago, this Yang geometry was deemed plausible.  Now hundreds of pages later and with weeks of further analysis this Yang geometry does NOT make sense.  We already discussed with you and I thought we had settled that the most important parameter is k r.   k r for Yang Shell is ridiculous:  it is much further from the apex than any other EM Drive. 

I am also the one that bothered to calculate the spherical radii r1 and r2 and the cone angles for all the EM Drives int the Wiki

Take a gander at r1 (the smaller spherical radius) for all the EM Drives in the wiki and compare them.  The one for Yang is off the charts, much further away from the apex.

Yes, it is much farther from the apex of the cone, but the half-angle is much smaller too, so the difference of impedance along the curve on Zeng and Fan puts it in the "same" ball park of delta-Z (change in impedance), that the other designs have. It makes sense to me. I do not see those dimensions as unreasonable.
Todd

Offline rfmwguy

  • EmDrive Builder (retired)
  • Senior Member
  • *****
  • Posts: 2165
  • Liked: 2681
  • Likes Given: 1124
NSF-1701 random thoughts on thermal management. As someone else pointed out, and empty microwave oven will cause a magnetron to overheat. This will also apply with a frustum. Can't help but think that Yang adressed the issue correctly with a circulator on the waveguide, which redirects reflected energy into a load.

Another option seemed to be EW using a dielectric, and I propose it was a non-conductive "heat sink" as opposed to an electrical match (whether they realized it or not).

So, off for some more testing this weekend. I'll make a tear-down and inspection video next.

Online Rodal

  • Senior Member
  • *****
  • Posts: 5838
  • USA
  • Liked: 5919
  • Likes Given: 5259
...

However, with the longer cylinder-like frustum, her half-angle is so small that extrapolating from the Impedance diagrams on Zeng and Fan, the part of the impedance curve and slope that cylinder is working on is about the same as it is for the other designs with more angle and shorter length. In other words, although her k*r value is in the 30's, the relative impedance shift is in the same ball park as the shorter designs with a larger angle. It may be that having less angle allows it to reach a much higher Q, like a cylinder but the shift in Z is still there to produce thrust.

@TT, if you look at the impedance graphs in Zeng and Fan, you can estimate what the impedance is as the distance k*r from the apex of the cone. That should eliminate the guessing.
Todd

Yes hundreds of pages ago, this Yang geometry was deemed plausible.  Now hundreds of pages later and with weeks of further analysis this Yang geometry does NOT make sense.  We already discussed with you and I thought we had settled that the most important parameter is k r.   k r for Yang Shell is ridiculous:  it is much further from the apex than any other EM Drive. 

I am also the one that bothered to calculate the spherical radii r1 and r2 and the cone angles for all the EM Drives int the Wiki

Take a gander at r1 (the smaller spherical radius) for all the EM Drives in the wiki and compare them.  The one for Yang is off the charts, much further away from the apex.

Yes, it is much farther from the apex of the cone, but the half-angle is much smaller too, so the difference of impedance along the curve on Zeng and Fan puts it in the "same" ball park of delta-Z (change in impedance), that the other designs have. It makes sense to me. I do not see those dimensions as unreasonable.
Todd

Good.  As SeeShells goes ahead with her Yang/Shell experiment we will see whether anybody is right, my analysis shows that the EM Drive Wiki dimensions I came up with for Yang are unreasonable. 

That's what great about experiments: it is where rubber hits the road :)

That's what experiments are for: test different hypothesis and measure what Mother Nature says.
« Last Edit: 08/01/2015 04:24 PM by Rodal »

Online Flyby

  • Full Member
  • ***
  • Posts: 382
  • Belgium
  • Liked: 447
  • Likes Given: 47
In Yang's original 2010 Chinese document the dimensions of the frustum are given by H1, D1(large base) and D2 small base. However, i could not find any matching numbers in the document.

On top of that, the drawing in that document differs from the more detailed drawing (the one with the waveguide) that it has no top/bottom cylindrical parts.

Below i did a large base matching between the 2 drawings... they clearly do not line up...


ps.
Come to think about it: would it be meaningful to have all the know drawings and "guesstimates" into one color-coded drawing, so that proportions of all the designs can be viewed simultaneously?
« Last Edit: 08/01/2015 04:35 PM by Flyby »

Offline Devilstower

  • Member
  • Posts: 23
  • Liked: 10
  • Likes Given: 6
@rfmwguy I wonder how the heat sink for a current generation Intel cpu might work? The kits are ubiquitous, come with thermal paste, and look to be about the right size for your magnetron.

Offline SeeShells

  • Senior Member
  • *****
  • Posts: 2326
  • Every action there's a reaction we try to grasp.
  • United States
  • Liked: 2956
  • Likes Given: 2589
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

Shell,

Using your Computer Aided Drawing program to assess the following figure:  https://forum.nasaspaceflight.com/index.php?action=dlattach;topic=37642.0;attach=1051616,

what

1) Cone half angle (angle between lateral side and perpendicular to base)

2) Ratio of internal Big Base diameter to internal Small Base diameter

3) Ratio of internal  Big Base diameter to internal Length perpendicular to bases

do you get ?

This would be helpful to better estimate dimensions.
Not quite sure where you would like to measure ratios but the cone angle is 15 degrees from the centerline.
I used 2.45 GHz to calculate the width of the waveguide at .12247 mm
Scaled the rest of the drawing to the same dim.
Looks like the ratio small end to big end is 1:1.5
Not sure where you would like to take the ratios on length and big end small end but I've left the dims in for you to choose.

Online Rodal

  • Senior Member
  • *****
  • Posts: 5838
  • USA
  • Liked: 5919
  • Likes Given: 5259
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

Shell,

Using your Computer Aided Drawing program to assess the following figure:  https://forum.nasaspaceflight.com/index.php?action=dlattach;topic=37642.0;attach=1051616,

what

1) Cone half angle (angle between lateral side and perpendicular to base)

2) Ratio of internal Big Base diameter to internal Small Base diameter

3) Ratio of internal  Big Base diameter to internal Length perpendicular to bases

do you get ?

This would be helpful to better estimate dimensions.
Not quite sure where you would like to measure ratios but the cone angle is 15 degrees from the centerline.
I used 2.45 GHz to calculate the width of the waveguide at .12247 mm
Scaled the rest of the drawing to the same dim.
Looks like the ratio small end to big end is 1:1.5
Not sure where you would like to take the ratios on length and big end small end but I've left the dims in for you to choose.

The important thing is that you also calculate cone half angle to be 15 degrees, in complete agreement with the others.

This is more than twice the cone half angle in the Wiki (that I came up with and I think are unreasonable)

Offline flux_capacitor

  • Full Member
  • ****
  • Posts: 552
  • France
  • Liked: 654
  • Likes Given: 906
I used 2.45 GHz to calculate the width of the waveguide at .12247 mm
Scaled the rest of the drawing to the same dim.

2.45 GHz microwaves do have a wavelength of 12.2 cm. However waveguides don't need to get that large to work. A WR340 waveguide (used by Tajmar for his magnetron) has a cross-section of 86.36 x 43.18 mm. This is the smallest standard waveguide we can use with microwave oven magnetrons. The size below is the WR-284 waveguide (72.136 x 34.036 mm) but it doesn't work below 2.60 GHz.

The half-cone angle of 15° is not affected of course. But I suggest we try also with the waveguide set at 86.36 mm.

Online Rodal

  • Senior Member
  • *****
  • Posts: 5838
  • USA
  • Liked: 5919
  • Likes Given: 5259
In Yang's original 2010 Chinese document the dimensions of the frustum are given by H1, D1(large base) and D2 small base. However, i could not find any matching numbers in the document.

On top of that, the drawing in that document differs from the more detailed drawing (the one with the waveguide) that it has no top/bottom cylindrical parts.

Below i did a large base matching between the 2 drawings... they clearly do not line up...


ps.
Come to think about it: would it be meaningful to have all the know drawings and "guesstimates" into one color-coded drawing, so that proportions of all the designs can be viewed simultaneously?

The difference between the two geometries is completely negligible compared to the difference between the geometry in the EM Drive wiki

Compared to the geometry in the EM Drive wiki, the two drawings you show line up excellent !



Could you please superpose the geometry of the EM Drive Wiki  ( http://emdrive.wiki/Experimental_Results ), which has a cone half angle of 6 degrees to make that clear ?

If you do that you will see how utterly different is the geometry in the EM Drive wiki for Yang, and that the estimate in the EM Drive Wiki is unreasonable.
« Last Edit: 08/01/2015 04:55 PM by Rodal »

Online Flyby

  • Full Member
  • ***
  • Posts: 382
  • Belgium
  • Liked: 447
  • Likes Given: 47

The difference between the two geometries is completely negligible compared to the difference between the geometry in the EM Drive wiki

Compared to the geometry in the EM Drive wiki, the two drawings you show line up excellent !



Could you please superpose the geometry of the EM Drive Wiki  ( http://emdrive.wiki/Experimental_Results ), which has a cone half angle of 6 degrees to make that clear ?

If you do that you will see how utterly different is the geometry in the EM Drive wiki for Yang, and that the estimate in the EM Drive Wiki is unreasonable.

Blue outline is the Wiki version of Yang...
As you said... it's way off..

Could it be that the composite shape of a cylinder and frustum, like we see in the more "technical" drawing, altered the data in such a way that reverse calculation gives a length value that is way off?
« Last Edit: 08/01/2015 05:12 PM by Flyby »

Online Rodal

  • Senior Member
  • *****
  • Posts: 5838
  • USA
  • Liked: 5919
  • Likes Given: 5259

The difference between the two geometries is completely negligible compared to the difference between the geometry in the EM Drive wiki

Compared to the geometry in the EM Drive wiki, the two drawings you show line up excellent !



Could you please superpose the geometry of the EM Drive Wiki  ( http://emdrive.wiki/Experimental_Results ), which has a cone half angle of 6 degrees to make that clear ?

If you do that you will see how utterly different is the geometry in the EM Drive wiki for Yang, and that the estimate in the EM Drive Wiki is unreasonable.

Blue outline is the Wiki version of Yang...
As you said... it's way off..

Could it be that the composite shape of a cylinder and frustum, like we see in the more "technical" drawing, altered the data in such a way that reverse calculation gives a value that is way off?

As I thought: EXCELLENT agreement between all the Yang drawigns

Wiki Yang geometry is way off.  Yang/Shell is NOT a good model of Yang's dimensions

No. I am the one and only one person that came up with the dimensions that are in the Wiki EM Drive wiki.  I know how I came up with those dimensions.  Either my interpretation of the tables or something else in her paper is off or she has a mistake in her paper.  Something is OFF by a huge amount.

There is NO basis on which to pretend that the dimensions in the EM Drive wiki represent Yang's geometry on the contrary. All the evidence is to the contrary

To start with, the all important cone half-angle is around 15 degrees instead of 6 degrees.

Yang's angle is close to NASA.

I look forward to Shell's test with a cone half-angle of only 6 degrees to prove this :)

Experiments have a way to settle things...

To make it simple:

Geometry close to a cylinder ===>  bad

Geometry close to Shawyer and NASA ===> good
« Last Edit: 08/01/2015 05:17 PM by Rodal »

Offline SeeShells

  • Senior Member
  • *****
  • Posts: 2326
  • Every action there's a reaction we try to grasp.
  • United States
  • Liked: 2956
  • Likes Given: 2589
I used 2.45 GHz to calculate the width of the waveguide at .12247 mm
Scaled the rest of the drawing to the same dim.

2.45 GHz microwaves do have a wavelength of 12.2 cm. However waveguides don't need to get that large to work. A WR340 waveguide (used by Tajmar for his magnetron) has a cross-section of 86.36 x 43.18 mm. This is the smallest standard waveguide we can use with microwave oven magnetrons. The size below is the WR-284 waveguide (72.136 x 34.036 mm) but it doesn't work below 2.60 GHz.

The half-cone angle of 15° is not affected of course. But I suggest we try also with the waveguide set at 86.36 mm.
I did the numbers for 2.45 GHz and then to seek agreement went to http://www.pasternack.com/t-calculator-wavelength.aspx?gclid=CNaLoaS9hccCFQ2OaQod9GMB1w
 and compared values, they agreed . Mostly this figure was to get ratios but I can see where you're coming from in resetting the waveguide distance. Can do.

Shell

Online Flyby

  • Full Member
  • ***
  • Posts: 382
  • Belgium
  • Liked: 447
  • Likes Given: 47
In Yang's 2014 papers there is a mentioning of a wave coupling window, for which we do have accurate dimensions.
L1 =43.34mm
L2 = 31.78mm

I know nothing about waveguides but is it logical that it is higher then it is large?

Because, just judging on the positions of the drilled holes (for bolting) of that window and comparing that to the shape and positioning of the 2 adjustment screws, that coupling window should be turned 90° and consequently, swapping the height/width dimensions...

It might help to get the dimensions of the waveguide from another angle then calculus?
« Last Edit: 08/01/2015 05:27 PM by Flyby »

Offline flux_capacitor

  • Full Member
  • ****
  • Posts: 552
  • France
  • Liked: 654
  • Likes Given: 906
I think you have it, Flyby! :)

Online Rodal

  • Senior Member
  • *****
  • Posts: 5838
  • USA
  • Liked: 5919
  • Likes Given: 5259
Great Internet collaboration!

We are getting there !

Offline WarpTech

  • Full Member
  • ****
  • Posts: 1228
  • Do it!
  • Vista, CA
  • Liked: 1295
  • Likes Given: 1749

The difference between the two geometries is completely negligible compared to the difference between the geometry in the EM Drive wiki

Compared to the geometry in the EM Drive wiki, the two drawings you show line up excellent !



Could you please superpose the geometry of the EM Drive Wiki  ( http://emdrive.wiki/Experimental_Results ), which has a cone half angle of 6 degrees to make that clear ?

If you do that you will see how utterly different is the geometry in the EM Drive wiki for Yang, and that the estimate in the EM Drive Wiki is unreasonable.

Blue outline is the Wiki version of Yang...
As you said... it's way off..

Could it be that the composite shape of a cylinder and frustum, like we see in the more "technical" drawing, altered the data in such a way that reverse calculation gives a value that is way off?

As I thought: EXCELLENT agreement between all the Yang drawigns

Wiki Yang geometry is way off.  Yang/Shell is NOT a good model of Yang's dimensions

No. I am the one and only one person that came up with the dimensions that are in the Wiki EM Drive wiki.  I know how I came up with those dimensions.  Either my interpretation of the tables or something else in her paper is off or she has a mistake in her paper.  Something is OFF by a huge amount.

There is NO basis on which to pretend that the dimensions in the EM Drive wiki represent Yang's geometry on the contrary. All the evidence is to the contrary

To start with, the all important cone half-angle is around 15 degrees instead of 6 degrees.

Yang's angle is close to NASA.

I look forward to Shell's test with a cone half-angle of only 6 degrees to prove this :)

Experiments have a way to settle things...

To make it simple:

Geometry close to a cylinder ===>  bad

Geometry close to Shawyer and NASA ===> good

So, what are the "NEW" dimensions of the Juan Yang cavity? I will update my spreadsheet.
Thanks.
Todd

Tags: