### Author Topic: EM Drive Developments - related to space flight applications - Thread 3  (Read 2326370 times)

#### X_RaY

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##### Re: EM Drive Developments - related to space flight applications - Thread 3
« Reply #5380 on: 07/27/2015 07:01 PM »
Let's hope someone who's reading the NSF do ask him tomorrow at the conference. Or even better, Martin Tajmar read this forum himself  and get all the interesting stuff from this community brain

#### cej

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##### Re: EM Drive Developments - related to space flight applications - Thread 3
« Reply #5381 on: 07/27/2015 07:10 PM »
I think that X-Ray, TheTraveller, Todd "WarpTech" got this right.  The dimensions are off by a factor of 2.

I'm not arguing about the other dimensions, only the length/height.

I read your post several times, and each time I thought that your concern was that the length of the cavity could be adjusted between experiments because you emphasized the adjustable endplate. Hence my last post arguing that the length would be fixed for all runs after initial calibration. However, I now see that you were instead arguing that both the diameters AND the length must be off by a factor of two. My apologies for misinterpreting you.

The internal length is actually less than 2 times the length given (the length is given by the aspect ratio in the COMSOL FEA)

But could you elaborate on why you think the length is also off by a factor of 2, i.e. that it should be less than 34.3 mm 137.2mm but is not 68.6 mm? If we assume that the big diameter is actually 108.2 mm, then a length of 68.6 mm seems to agree with the proportions in the COMSOL diagram because it is less than the diameter.
« Last Edit: 07/27/2015 07:28 PM by cej »

#### aceshigh

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##### Re: EM Drive Developments - related to space flight applications - Thread 3
« Reply #5382 on: 07/27/2015 07:10 PM »
Let's hope someone who's reading the NSF do ask him tomorrow at the conference. Or even better, Martin Tajmar read this forum himself  and get all the interesting stuff from this community brain

unfortunatelly, it may have been moved to TODAY afternoon... either that or AIAA conference website has a typo

NFF-04. Future Flight Propulsion Systems
Chair(s): Gregory Meholic (The Aerospace Corporation)
Co-Chair(s): Heidi Fearn (California State University, Fullerton)
2:30 PM - 5:30 PM; Lake Nona A

but the type of the conference is labelled as "Technical Paper"
Session Title:Future Flight Propulsion Systems
Session Notes: Monday Afternoon
Session Type: Technical Paper
Session Topic: 51st AIAA/SAE/ASEE Joint Propulsion Conference
Chair: Gregory V Meholic
Co-Chair: Heidi Fearn
Location: Lake Nona A

the final program PDF however still lists it to tuesday

« Last Edit: 07/27/2015 07:14 PM by aceshigh »

#### X_RaY

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##### Re: EM Drive Developments - related to space flight applications - Thread 3
« Reply #5383 on: 07/27/2015 07:13 PM »
I show the calculated TE111 Electric Field in theta polar direction for Tajmar's TU Dresden University EM Drive, to compare it with his COMSOL FEA calculation

Assumed dimensions:

Big diameter = 0.1062 m = (2*0.0541m - 0.002 m)
Small diameter = 0.075 m = (2*0.0385 m - 0.002 m)
Axial Length = 0.100842 m =  0.735*2*0.0686 m

As per TheTraveller I have subtracted 2 mm for copper thickness from the external dimensions, however this has a negligible influence on the results

The axial internal length is 73.5% of the exterior length (it is adjusted internally with a screw prior to testing)

TE111 Natural frequency = 2.446 GHz

I enclose strictly for discussion, research and illustration purposes Fig. 2 a of Tajmar et.al. COMSOL FEA analysis for comparison with my calculations

“…for purposes such as criticism, comment, news reporting, scholarship, or research…” under US Fair Use

http://fairuse.stanford.edu/overview/fair-use/what-is-fair-use/

This is the  American Institute of Aeronautics and Astronautics link to Martin Tajmar's et.al. paper, that should be obtained from the American Institute of Aeronautics and Astronautics:

Direct Thrust Measurements of an EM Drive and Evaluation of Possible Side-Effects  M. Tajmar and G. Fiedler
51st AIAA/SAE/ASEE Joint Propulsion Conference

http://arc.aiaa.org/doi/pdf/10.2514/6.2015-4083
Great work Dr. Rodal!
Can you please simulate the situation with the dimensions direct from the paper (to be diameter) to confirm the results and post the resulting picture?
The small flat endplate, don't will give huge differences in contrast to your calculation, i think.

EDIT: After that please let's go back and focus to the possible explanations of the thrust effect.
« Last Edit: 07/27/2015 08:02 PM by X_RaY »

#### Rodal

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##### Re: EM Drive Developments - related to space flight applications - Thread 3
« Reply #5384 on: 07/27/2015 07:18 PM »
...But could you elaborate on why you think the length is also off by a factor of 2, i.e. that it should be less than 34.3 mm? If we assume that the big diameter is actually 108.2 mm, then a length of 68.6 mm seems to agree with the proportions in the COMSOL diagram.
Because I can calculate the effect of different lengths on natural frequency, and mode shapes, and we know that the excitation frequency was 2.45 GHz

#### WarpTech

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##### Re: EM Drive Developments - related to space flight applications - Thread 3
« Reply #5385 on: 07/27/2015 07:25 PM »
I think that X-Ray, TheTraveller, Todd "WarpTech" got this right.  The dimensions are off by a factor of 2.

I'm not arguing about the other dimensions, only the length/height.

I read your post several times, and each time I thought that your concern was that the length of the cavity could be adjusted between experiments because you emphasized the adjustable endplate. Hence my last post arguing that the length would be fixed for all runs after initial calibration. However, I now see that you were instead arguing that both the diameters AND the length must be off by a factor of two. My apologies for misinterpreting you.

The internal length is actually less than 2 times the length given (the length is given by the aspect ratio in the COMSOL FEA)

But could you elaborate on why you think the length is also off by a factor of 2, i.e. that it should be less than 34.3 mm? If we assume that the big diameter is actually 108.2 mm, then a length of 68.6 mm seems to agree with the proportions in the COMSOL diagram.

The WR340 wave guide feeding it is 138 mm, therefore, it can't be 68.6mm tall. It must be twice as tall as what was reported. I'd bet they measured 68.6 mm from the origin of coordinates, at the center of the frustum.

#### aero

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##### Re: EM Drive Developments - related to space flight applications - Thread 3
« Reply #5386 on: 07/27/2015 07:48 PM »
I think that X-Ray, TheTraveller, Todd "WarpTech" got this right.  The dimensions are off by a factor of 2.

I'm not arguing about the other dimensions, only the length/height.

I read your post several times, and each time I thought that your concern was that the length of the cavity could be adjusted between experiments because you emphasized the adjustable endplate. Hence my last post arguing that the length would be fixed for all runs after initial calibration. However, I now see that you were instead arguing that both the diameters AND the length must be off by a factor of two. My apologies for misinterpreting you.

The internal length is actually less than 2 times the length given (the length is given by the aspect ratio in the COMSOL FEA)

But could you elaborate on why you think the length is also off by a factor of 2, i.e. that it should be less than 34.3 mm? If we assume that the big diameter is actually 108.2 mm, then a length of 68.6 mm seems to agree with the proportions in the COMSOL diagram.

The WR340 wave guide feeding it is 138 mm, therefore, it can't be 68.6mm tall. It must be twice as tall as what was reported. I'd bet they measured 68.6 mm from the origin of coordinates, at the center of the frustum.

But note that 68.6 mm times 2 is only 137.2 mm, still short even though very close.
Retired, working interesting problems

#### Rodal

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##### Re: EM Drive Developments - related to space flight applications - Thread 3
« Reply #5387 on: 07/27/2015 07:55 PM »
The Chinese are very quick to capitalise on new stuff. They also have someone who claims to have the best performance figure ever recorded for a frustum.

And yet...

Notice  "Reference Number 9" in Martin Tajmar et.al.'s paper is:

Quote
Ref. 9  Costello, J.P., "Why Shawyer’s ‘electromagnetic relativity drive’ is a fraud",http://johncostella.webs.com/shawyerfraud.pdf
(Accessed 5th July 2015)

as part of this remark:

Quote
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

I would have thought that Greg Egan, John Baez and Sean Carroll would have made for a more scholastic skeptical reference to use.
« Last Edit: 07/27/2015 07:57 PM by Rodal »

#### deltaMass

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##### Re: EM Drive Developments - related to space flight applications - Thread 3
« Reply #5388 on: 07/27/2015 07:59 PM »
At least an explanation exists for why the Chinese don't already have production lines for churning out EmDrives. Can there be any other excuse?
« Last Edit: 07/27/2015 08:00 PM by deltaMass »

#### mittelhauser

##### Re: EM Drive Developments - related to space flight applications - Thread 3
« Reply #5389 on: 07/27/2015 08:02 PM »
So if you or one of your friends within that 50 mile radius want to put a couple bucks to help not to make more millions but because they choose to dream, I'll welcome it.

Shell

*grin*  I put a little into your fund the day you started it.  Like I said, I want to believe.  I'll have a lot more faith in your data (once you have it) than random unsubstantiated statements.

#### Rodal

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##### Re: EM Drive Developments - related to space flight applications - Thread 3
« Reply #5390 on: 07/27/2015 08:16 PM »
I think that X-Ray, TheTraveller, Todd "WarpTech" got this right.  The dimensions are off by a factor of 2.

I'm not arguing about the other dimensions, only the length/height.

I read your post several times, and each time I thought that your concern was that the length of the cavity could be adjusted between experiments because you emphasized the adjustable endplate. Hence my last post arguing that the length would be fixed for all runs after initial calibration. However, I now see that you were instead arguing that both the diameters AND the length must be off by a factor of two. My apologies for misinterpreting you.

The internal length is actually less than 2 times the length given (the length is given by the aspect ratio in the COMSOL FEA)

But could you elaborate on why you think the length is also off by a factor of 2, i.e. that it should be less than 34.3 mm? If we assume that the big diameter is actually 108.2 mm, then a length of 68.6 mm seems to agree with the proportions in the COMSOL diagram.

The WR340 wave guide feeding it is 138 mm, therefore, it can't be 68.6mm tall. It must be twice as tall as what was reported. I'd bet they measured 68.6 mm from the origin of coordinates, at the center of the frustum.

But note that 68.6 mm times 2 is only 137.2 mm, still short even though very close.

The internal dimensions of WR340 are significantly smaller : 86.36 mm length, and the hole distance 119.06 mm to fix the waveguide is 18.14 mm under the 2x68.6mm = 137.2 mm Tajmar EM Drive length, so no problem in using WR340, look at this drawing:

The holes are 6.35 mm diameter, so that takes 6.35 mm/2 = 3.175 mm off the side of the 18.14 mm/2 = 9.07mm, giving 5.895 mm, almost 6 mm to spare (about the diameter of the holes) of extra room in the length.

The slight difference between 2x68.6mm = 137.2 mm and 138.1 mm = 138.1mm - 137.2mm = 0.9 mm, slightly less than 1 mm, is only aesthetic, playing no structural or microwave electromagnetic field relevance in the attachment.

X-Ray (foremost), TheTraveller, Todd "WarpTech" got this right.

« Last Edit: 07/27/2015 08:29 PM by Rodal »

#### rfmwguy

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##### Re: EM Drive Developments - related to space flight applications - Thread 3
« Reply #5391 on: 07/27/2015 08:55 PM »
At least an explanation exists for why the Chinese don't already have production lines for churning out EmDrives. Can there be any other excuse?
Lack of power at ground level. Lack of millions of potential buyers. Translation; lack of market.

#### Rodal

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##### Re: EM Drive Developments - related to space flight applications - Thread 3
« Reply #5392 on: 07/27/2015 09:10 PM »
At least an explanation exists for why the Chinese don't already have production lines for churning out EmDrives. Can there be any other excuse?
Lack of power at ground level. Lack of millions of potential buyers. Translation; lack of market.
Which are not a problem for the well-funded Chinese Air Force and Space Program.  Lack of a market has not impeded their on-going Taikonaut and Mini-Space Station programs, Space Defense tests, as well as their long-term programs including ion-drives and Moon program.  So, why no deployment of the Yang EM Drive in Space, if it can really do what is claimed?

#### QuantumG

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##### Re: EM Drive Developments - related to space flight applications - Thread 3
« Reply #5393 on: 07/27/2015 09:14 PM »

Which are not a problem for the well-funded Chinese [..] Space Program.

What makes you think it's well funded? Last I heard, the best estimates put it below ESA.. i.e., about a third of the US program.
Human spaceflight is basically just LARPing now.

#### A_M_Swallow

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##### Re: EM Drive Developments - related to space flight applications - Thread 3
« Reply #5394 on: 07/27/2015 09:19 PM »
At least an explanation exists for why the Chinese don't already have production lines for churning out EmDrives. Can there be any other excuse?
Lack of power at ground level. Lack of millions of potential buyers. Translation; lack of market.
Which are not a problem for the well-funded Chinese Air Force and Space Program.  Lack of a market has not impeded their on-going Taikonaut and Mini-Space Station programs, Space Defense tests, as well as their long-term programs including ion-drives and Moon program.  So, why no deployment of the Yang EM Drive in Space, if it can really do what is claimed?

Possibly because the Chinese are not copying or acting as a subcontractor for EM Drives but leading. Their industrial management procedures are not set up for that.

#### mrseanpaul81

##### Re: EM Drive Developments - related to space flight applications - Thread 3
« Reply #5395 on: 07/27/2015 09:20 PM »
The device used by Tajmar looks more like a version of Shawyer's first fustrum than the latest work by Yang, et al.  It would be very nice if we could get actual schematics of Tajmar's fustrum rather than squinting at pictures trying to figure out what he did...

Yes I agree it is very the Experimental EMDrive except Shawyer got 16mNs out of his.

It took him several years to get it right. Q was 5,900 but that was because it had a dielectric inside. He used 5 magnetrons, burnt out 3 and burned a hole in a waveguide. But he got there.

His experimental data was verified by a expert Uk aerospace industry group set up by the UK gov Dept of Defense. After the experts gave him the thumbs up, the UK gov gave him the 1st grant to build the Demonstrator EMDrive and the rotary test rig.

After the UK gov again verified the data from the Demonstrator trials he got the final payment from the UK gov.

Sigh.  I'll try one more time.  You keep making these statements over and over.  However, you have provided no evidence to support those statements.  Who were the experts who "verified" it?  Where is a document which shows what was verified?  Etc, etc.  You promised us a paper which would end all doubts and all that was produced was an old paper which didn't have any new experimental data.

I *really* want to be a believer and you make it extremely difficult.   I'll say once again, stop posting blindly optimistic projections and focus on your build and get some data which can be independently verified and which shows what you claim...Please!  I'm wishing you luck.

Frankly, if this had been truly verified at the levels you imply, funding wouldn't be an issue and folks wouldn't be scrambling to do FundMe's for DIY versions.  I sit within 50 miles of a LOT of people who would happily throw millions at the project if there was evidence such as you keep insisting already exists.
Here is a builder who isn't either way, I'm an engineer who can be optimistic, but in the end I rely on data. I've seen some proof in NASA's EagleWorks and in the current tests which are verified. The Chinese could be questioned if you want.

There are many things that could lead to aberrations in thrust, I'll agree in that point, but what's interesting, each test is a little different with different jigs to test, different power, different cavities, different sizes, in vacuum or not and the list is quite extensive.

The few things in all of those that have reported thrust (verified or not) is that have is they injected microwaves into a resonate conical enclosed cavity and thrust was measured. I have looked for the common ingredient other than those I just listed and there doesn't seem to be one at all.  I'm not alone, as there are very sharp skeptics picking it apart.

It's good enough for me to take what little I got from gofundme and my own pocket and pick apart this bit by bit test by test to get to a truth in why this simple device has confounded some of the finest minds around. Answers are not going to take millions but a well designed tests could for a few thousand. When I'm over and done and have solid answers and maybe the key, I'll share it. So if you or one of your friends within that 50 mile radius want to put a couple bucks to help not to make more millions but because they choose to dream, I'll welcome it.

Shell

I am game. Maybe you can get a kickstarter togetger. I would contribute and I am sure more people would too

#### deltaMass

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##### Re: EM Drive Developments - related to space flight applications - Thread 3
« Reply #5396 on: 07/27/2015 09:27 PM »

Which are not a problem for the well-funded Chinese [..] Space Program.

What makes you think it's well funded? Last I heard, the best estimates put it below ESA.. i.e., about a third of the US program.
What makes you think it's not well funded? After all, it's claimed to be a revolutionary propulsion paradigm. The chief reason that would occur to most people is that it's not funded because it doesn't actually work. I wonder if there'll be a paper about that.

#### Rodal

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##### Re: EM Drive Developments - related to space flight applications - Thread 3
« Reply #5397 on: 07/27/2015 09:27 PM »

Which are not a problem for the well-funded Chinese [..] Space Program.

What makes you think it's well funded? Last I heard, the best estimates put it below ESA.. i.e., about a third of the US program.
Based on the information I have seen on their actual facilities, equipment, and installations.  You should be skeptic about the estimates based on Chinese numbers translated to Western currency, as 1) they have an incentive to hide the true expenditures as they don't want to be seen as an offensive program for political reasons and 2) everything made in China is much less expensive (when translated to strong currencies like Euros or USD) than in Europe or the US, due to the lower salaries, costs, etc.

So rather than saying "well funded in Western strong currency" (not to be interpreted in Euros or USD denomination) I mean the actual facilities and research and technical equipment they have, as well as their actual Space Launching abilities.    I would not put the Europeans as a human-crew Space Power comparable to the Chinese, as, for example, the Chinese can put taikonauts in Space all on their own resources.

If the EM Drive would be that close to reality as claimed, and if Yang's EM Drive would be something that could be usefully deployed in Space right now, I fully would have expected the Chinese to have deployed it. (*)

(*) Note Yang's reaction to Wembley's article: she said that publicity concerning their program is most unwelcome and that it was strictly academic.  There are two opposite ways to interpret this statement of course, but it shows once again that the Chinese don't want to be seen as having a military Space program.
« Last Edit: 07/27/2015 09:44 PM by Rodal »

#### rfmwguy

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##### Re: EM Drive Developments - related to space flight applications - Thread 3
« Reply #5398 on: 07/27/2015 09:28 PM »
At least an explanation exists for why the Chinese don't already have production lines for churning out EmDrives. Can there be any other excuse?
Lack of power at ground level. Lack of millions of potential buyers. Translation; lack of market.
Which are not a problem for the well-funded Chinese Air Force and Space Program.  Lack of a market has not impeded their on-going Taikonaut and Mini-Space Station programs, Space Defense tests, as well as their long-term programs including ion-drives and Moon program.  So, why no deployment of the Yang EM Drive in Space, if it can really do what is claimed?
This is a better point. It would not surprise me that Yang going silent and chinese space development are related. Perhaps a similar thing is happening at NASA. The EW boys are strangely quiet...by design I read.

Best I can tell, the Chinese space program is not set up for PR for the masses. Everything they do or fail to do is guarded, their moon lander is an example. Not sure they're into the sharing mode on their technology, especially disruptive technology.

<edit> further thoughts
« Last Edit: 07/27/2015 09:36 PM by rfmwguy »

#### deltaMass

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##### Re: EM Drive Developments - related to space flight applications - Thread 3
« Reply #5399 on: 07/27/2015 09:37 PM »
@Rodal or anyone for that matter know how to calculate shawyer's design factor?
Shawyer's Df equation is attached. Have verified with Shawyer that it is correct.
Writing x0,x1,x2 for the 3 lambdas, this can be expressed as
D = [(1-a)/sqrt(a)] * [sqrt(b)/(1-b)], where a = x1/x2, b = x02/(x1*x2)
Notice that D is a separable function of a,b and so can be readily optimised by inspection.
Dmax -> infinity when a->0 and/or b->1.
Do other relations between x0,1,2 exist to prevent D becoming infinite?
Obviously if a > 0 and b < 1 then Dmax when a is min, b is max
I would like to know the maximum theoretical value of Df.
Based on the expression I derived above, it corresponds to
- a min, i.e. (x1/x2) min
- b max, i.e. x02/(x1*x2) max.

What are the values of aMin and bMax, and why?

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