### Author Topic: EM Drive Developments - related to space flight applications - Thread 3  (Read 2293032 times)

#### SeeShells

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##### Re: EM Drive Developments - related to space flight applications - Thread 3
« Reply #6180 on: 08/02/2015 03:14 PM »
We are so working in the dark here and I've found evidence we have been trumped by one of the greats already.
http://www.villesresearch.com/images/teslacone.jpg

BTW he (Tusla) is running about 21.69 degrees cone angle.
« Last Edit: 08/02/2015 03:51 PM by SeeShells »

#### SeeShells

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##### Re: EM Drive Developments - related to space flight applications - Thread 3
« Reply #6181 on: 08/02/2015 03:23 PM »
...

Shell
1) Concerning estimation of Yang's dimensions:

Everybody is welcome to come up with their own estimates for Yang's dimensions.  So far, to  my recollection, I'm the only one that estimated Yang's dimensions, with two different and clearly stated assumptions: A) assuming the cut-off condition for the small diameter and alternatively B) assuming the angle from the drawings to be approximately correct.

To all readers disagreeing: what is your estimate for Yang's dimensions and what is it based on?

Let's compare different estimates and the basis for calculating the different estimates.

_____

2) Concerning experiments:

The formulas (Shawyer, McCulloch, Notsosureofit), as well as the Meep results and my computations show that the results based on an approximately cylindrical frustum with 6 degree cone angle are going to be inferior to  one with a larger cone angle.

Concerning the experiments, I very much look forward to have experiments with a frustum having only 6 degree cone half-angle to compare with the experiments with frustum having higher cone angles.

An experiment will really clear this.  Just like Tajmar's experiment with a Q=50 clarified the relationship to Q.
I even printed off pictures after changing them to line drawings in software and took my handy dandy protractor to measure and I was all over the place in differences in the pictures and the drawings. The best I could come up with was was disagreeing angles.

I did go the old fashioned route with pen and paper.

Shell

#### Rodal

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##### Re: EM Drive Developments - related to space flight applications - Thread 3
« Reply #6182 on: 08/02/2015 03:30 PM »
...I even printed off pictures after changing them to line drawings in software and took my handy dandy protractor to measure and I was all over the place in differences in the pictures and the drawings. The best I could come up with was was disagreeing angles.

I did go the old fashioned route with pen and paper.

Shell

How much "all over the place"?  Did you get an angle of only 6 degrees from any of those pictures?

Neither Flyby nor FluxCapacitor or me report an angle of 6 degrees from any of Yang's pictures.

Blue is the cavity with 6 degrees: (it looks practically like a cylinder, compared to the other two):

« Last Edit: 08/02/2015 03:46 PM by Rodal »

#### SeeShells

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##### Re: EM Drive Developments - related to space flight applications - Thread 3
« Reply #6183 on: 08/02/2015 03:49 PM »
...I even printed off pictures after changing them to line drawings in software and took my handy dandy protractor to measure and I was all over the place in differences in the pictures and the drawings. The best I could come up with was was disagreeing angles.

I did go the old fashioned route with pen and paper.

Shell

How much "all over the place"?  Did you get an angle of only 6 degrees from any of those pictures?

Neither Flyby nor FluxCapacitor or me report an angle of 6 degrees from any of Yang's pictures.

Blue is the cavity with 6 degrees: (it looks practically like a cylinder, compared to the other two):

Nope not a one. So i picked a dimensionality that came from calculations (yours and me following them and I didn't catch the booboo either and that's on me) and reported high thrusts and built it. I was wrong and you were wrong, it happens. So I'm left with some of my original plans of testing this design and modifying it some to test out some other ideas. No bad data Jose'. It could be a good test run to iron out all of the test bed issues and fine tune all of it.

If I get crappy thrust we can just add the data to the charts filling them out. I have a \$200 piece of O2 free copper that I ordered that will be my next build drawing on what I see here and what comes out of the test of the Yang-Shell and I believe that will be better for testing.

shell

#### SeeShells

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##### Re: EM Drive Developments - related to space flight applications - Thread 3
« Reply #6184 on: 08/02/2015 04:16 PM »
Yang's frustum has the following dimensions:

- cavity length (m): 0.24
- big diameter (m): 0.201
- small diameter (m): 0.1492

In particular, the big end is smaller than the height, not larger.

There is no resonance I can find for those dimensions at 2.45GHz. Can get TE012 resonance at 2.51GHz

They were surely wrong dimensions, based on the assumption Yang's drawings had the correct proportions. ..

No, they were the dimensions that I had correctly based on the assumption that the small diameter for Yang was obtained based on the cut-off condition for the small end.  And TheTraveller's calculation actually confirms it:

<<There is no resonance I can find for those dimensions at 2.45GHz. Can get TE012 resonance at 2.51GHz>>

The 2% difference between 2.45 GHz and 2.51 GHz is completely and utterly negligible compared to the other differences we are talking about: compared to the difference between 6 degrees and 15 degrees for the cone half-angle or compared to the uncertainties in having to eyeball the dimensionless ratio equations from Yang's chart.

On top of that, the result TE012 resonance at 2.51GHz is obtained by TheTraveller from an Excel spreadsheet using very simplified ad-hoc approximate formulas that do not respect the boundary conditions of the problem while the solution for TE012 2.45GHz resonance uses Wolfram Mathematica to solve the exact solution to the problem using Legendre Associated Functions and Spherical Bessel functions.

Taking into account the above considerations, the 2% different ad-hoc TE012 resonance at 2.51GHz means a complete agreement with the dimensions provided, because the 2% difference is completely within bounds.

___________________________________________

The issue at hand (determination of Yang's geometry) has to do with whether L=24cm provided by Yang in her paper is correct, and if so, whether the other (one and only one available to choose) parameter to consider should be the small diameter (based on cut-off), or the cone half-angle (determined from drawings), or some other parameter like D/L (determined from drawings), etc.

One cannot obtain dimensions from Yang's schematic drawings, one can only obtain dimensionless ratios: angles and ratios, that's it.

For L=24 cm and f=2.45 GHz, you cannot satisfy both that the diameter of the small base be above cut-off for an open waveguide AND satisfy the cone half-angle from Yang's drawings .  They are in violent conflict with each other.  Something got's to give.

This has to be clearly understood:  we have mathematical relations to satisfy here, they are mathematical constraints.  You cannot satisfy all the dimensionless ratios from Yang's drawings and simultaneously satisfy the cut-off condition at the small end and simultaneously satisfy L=24 cm and simultaneously satisfy the D/L vs frequency relation.

I'd like to insert one other thing here as well, having been in the middle of this as one of the builders. First I understand the why of your calculations and how you arrived at them.

Numbers don't lie, but liars and the deceiving will number. That said I think we need to at least make sure that the cone angle for Yang's frustum is correct, better than just taking it off of Yang's drawings which have been proven to be not quite accurate. How do we know that the drawing wasn't modified to fit the page ie: shortening or lengthening the image changing the cone angle? How can we even know who drew this and in what program? PCPaint? The answer is, we truly cant. That throw the angles and ratios under question as well.

Unless you are aware of a designed numerical conditions and guides that promotes this anonymously vague thing called thrust (don't think any here are) we still are poking the bear in the dark. How can I design something to optimize thrust when we don't even know what causes it and then throw in the misleading facts and figures from other builders and we have a real corundum on our hands. (ack, Shell runs screaming into the woods here) Numbers don't lie, but confusion in reported numbers or intentional misreporting of them makes for bad designing.

I'm not going to throw bricks or mash up my frustum with it but I have much to do in the building of the test stand and I'm gonna sortta float for awhile seeing if better numbers come forth.

Shell

BTW I am going to be using a messy magnetron.
http://imgur.com/uL7VRi9

#### Flyby

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##### Re: EM Drive Developments - related to space flight applications - Thread 3
« Reply #6185 on: 08/02/2015 04:17 PM »
Shell,

I think your narrow angled frustum is an ideal case to test Todd's theory, needing a long narrow shape.

If it works better then all the rest, then we've all learned what direction to take for better results...

If it doesn't, it might indicate that Shawyer's path might yield better results.

So, whatever the outcome, your findings and data will bring an important contribution...

I too still have mixed feelings about the accuracy of Yang's frustrum+waveguide "technical drawing".
Some aspects make it read as a genuine technical illustration, where other aspects turn it "make believe" technical drawing that in essence hold no true dimensioning, scaling or proportion...
If only there was more consistency in the drawings and they had measurements on them... sigh...

#### SeeShells

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##### Re: EM Drive Developments - related to space flight applications - Thread 3
« Reply #6186 on: 08/02/2015 04:25 PM »
Shell,

I think your narrow angled frustum is an ideal case to test Todd's theory, needing a long narrow shape.

If it works better then all the rest, then we've all learned what direction to take for better results...

If it doesn't, it might indicate that Shawyer's path might yield better results.

So, whatever the outcome, your findings and data will bring an important contribution...

I too still have mixed feelings about the accuracy of Yang's frustrum+waveguide "technical drawing".
Some aspects make it read as a genuine technical illustration, where other aspects turn it "make believe" technical drawing that in essence hold no true dimensioning, scaling or proportion...
If only there was more consistency in the drawings and they had measurements on them... sigh...
Thanks.
Sure make it hard poking that bear in the dark doesn't it? Todd's thoughts were seriously taken in consideration in this design and I dearly hope I can get him some well deserved data to plug into his theories.
When I fell onto this design I went oh my I can test this and this and this in one frustum I really guess it hasn't changed too much. So it's good and no brick.

Shell

#### Flyby

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##### Re: EM Drive Developments - related to space flight applications - Thread 3
« Reply #6187 on: 08/02/2015 05:35 PM »
Well, i have no clear view on the current status of Todd's ideas are, as they tend to evolve rather quickly, but I'm sure that at certain stage it was mentioned in one of his posts...

I do think it is very helpful to tailor the DIY projects according some of the theories that float around, as these tests might help to prove or disprove an idea/theory.
The faster we're clearing this forest of theories and ideas, the better it will be.. no?
« Last Edit: 08/02/2015 05:39 PM by Flyby »

#### WarpTech

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##### Re: EM Drive Developments - related to space flight applications - Thread 3
« Reply #6188 on: 08/02/2015 06:01 PM »
Shell,

I think your narrow angled frustum is an ideal case to test Todd's theory, needing a long narrow shape.

If it works better then all the rest, then we've all learned what direction to take for better results...

If it doesn't, it might indicate that Shawyer's path might yield better results.

So, whatever the outcome, your findings and data will bring an important contribution...

I too still have mixed feelings about the accuracy of Yang's frustrum+waveguide "technical drawing".
Some aspects make it read as a genuine technical illustration, where other aspects turn it "make believe" technical drawing that in essence hold no true dimensioning, scaling or proportion...
If only there was more consistency in the drawings and they had measurements on them... sigh...

To be clear, even in my theory the prediction is that a shorter length with wider angle will give more thrust "forward". However, there are just as large, if not larger forces acting on the side walls when it is long and narrow and evanescent waves are decaying into the small end. The difference is that the force vector is not directed as much toward the front and is more like a cylinder.

In any case, I end up with Length in the denominator when comparing relative phase velocities, or I end up with sin(theta) in the numerator when comparing electromagnetic pressures on the surfaces. Either way, more angle results in more thrust. Too much angle and it starts to look like a pillbox and is too symmetrical, IMO.

On the other hand, the impedance plots from Z&F show that the impedance is scalable wrt. k*r and has higher differentials at lower cone angles. So, I do not see offhand why it would not work if the k*r value is scaled accordingly, to oscillate along the same impedance gradient. Maybe the right k value will not resonate there?

Just so everyone knows, I currently have 3 different models I'm trying to reconcile. Multiple examples in the paper should drive the point home:

1. I have a model similar to @Notsosureofit's equation, but using Z&F Impedance plots for the velocity terms, that are very similar to the Reissner-Nordstrom metric potential.

2. I have a DC coaxial model for TM DC mode, where the cone has a copper central axis. From there I've calculated the magnetic pressures and if the large end is closed and current flows around the complete loop, (a 1 turn inductor), then the force sums to zero. However, if the big end is open, or no current flows through it, then the forces are not balanced and magnetic flux escapes out the big end. Provided there is enough leakage that doesn't couple back to the incoming power wires, there should be "some" thrust.

3. I have a DC cone model for TE DC mode, where the cone is open ended. Circulating current around the small circumference will be "pushed" to the big end as the magnetic flux expands and forces itself out the back. This one is interesting because the conical conductor rotates the EM momentum vector, p = q*A 90 degrees until it is parallel with the cone and exerts a thrust. Like pushing out magnetic doughnuts (toroids).

Then I have all the other theories that I'm trying to compare to and reconcile against. There are definitely ways to generate thrust, however generating thrust better than a photon rocket can only happen when both the group velocity AND the phase velocity are BOTH slower than light in free space. That's the tricky part that is not textbook microwave physics.
Todd

#### SeeShells

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##### Re: EM Drive Developments - related to space flight applications - Thread 3
« Reply #6189 on: 08/02/2015 06:27 PM »
Well, i have no clear view on the current status of Todd's ideas are, as they tend to evolve rather quickly, but I'm sure that at certain stage it was mentioned in one of his posts...

I do think it is very helpful to tailor the DIY projects according some of the theories that float around, as these tests might help to prove or disprove an idea/theory.
The faster we're clearing this forest of theories and ideas, the better it will be.. no?
Todd, when I get to the point where I can test some thoughts you we should exchange notes.

Thanks for the summaries it's much clearer now.

Shell

>>>Back to the lab Igor!
« Last Edit: 08/02/2015 06:34 PM by SeeShells »

#### Flyby

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##### Re: EM Drive Developments - related to space flight applications - Thread 3
« Reply #6190 on: 08/02/2015 06:35 PM »
hop.... another misunderstanding out the window...

#### X_RaY

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##### Re: EM Drive Developments - related to space flight applications - Thread 3
« Reply #6191 on: 08/02/2015 07:03 PM »

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?

The only dimension given by Yang in her paper is the Length (also called height) measured perpendicular to the bases.  It is 0.240 meters.

Look at page 811, Table 1  http://www.emdrive.com/NWPU2010paper.pdf

Hence it would be best if you superpose all the images so that they all have the same length: 0.240 meters

Then one has to use this image:

knowing that

1) L=24 cm

2) f = 2.45 GHz

3) D = (Dbig + Dsmall)/2

4) TE012  line should be used

OK, using the above and

Cone half-angle = 15 degrees

I proceed as follows:

TE012 Equation (from Yang's graph):   y = 13.5 + 8.5 x

where

y = ((f D) ^2)*10^(-20)
x = (D/L)^2

replacing

L=24 cm
f=2.45*10^9 Hz

and solving the quadratic equation for D, I get

D=17.26915 cm

and since

(Db - Ds)/2 = (24 cm)* tan (15 degrees)

and

(Db + Ds)/2 =D = 17.26915 cm

and solving these coupled equations for Db and Ds, we finally get

Db = 23.69993 cm ~ 23.70 cm

Ds  = 10.83836 cm ~ 10.84 cm

L = 24 cm

Need to calculate whether these numbers give a natural frequency for TE012 of 2.45 GHz

if not, need to modify the diameters in order to get TE012 @ 2.45 GHz

The main imprecision comes from the coefficients of the equation   y = 13.5 + 8.5 x

Obviously, there is a whole family of solutions that satisfy the equation for TE012 in Yang's graph, for different values of the cone angle.  The larger the cone angle, the more different are the values of Db and Ds, all we know is their average D.
After a 5 mile run, I'm ready to put this to bed.

We proceed as follows:

We adopt the Cone half-angle value from Flyby 15.44 degrees, which is the Median of the three values obtained (15 degrees from SeeShells and the two values from Flyby 15.44 and 18.27 degrees)

Cone Half-Angle = 15.44

therefore the constraint is

Db - Ds = 2 (24 cm) Tan(15.44) = 13. 25746 cm

and vary Db and Ds subject to this constraint to get 2.45 GHz for TE012 from the exact solution

doing so, we get:

Db = 0.247 m

Ds  = 0.114425 m

L = 0.24 m

r1= 0.211022 m

r2= 0.455515 m

Cone half-angle = 15.44 degrees

these numbers represent only a small change from the previous numbers, which gives some level of encouragement, as the previous numbers were obtained from Yang's chart, just eyeballing it, without performing any frequency calculation

Notice that these diameters for Yang are close to the diameters of Shawyer's Flight Thruster, the only difference with Flight Thruster is that Yang has a greater length to enable resonating at TE012 for Yang at 2.45GHz instead of TE013 for Flight Thruster at 3.85GHz.   Recall that at the time that Yang embarked on her project, the Flight Thruster was the latest and highest effective force design by Shawyer.  The longer length of Yang being motivated perhaps by the need to resonate at 2.45 GHz instead of 3.85 GHz.

We adopt these numbers as the official Yang geometry and we correct the previous numbers I had entered in the EM Drive Wiki accordingly without further ado.

***A cone half-angle of 6 degrees does not make any sense to me for an EM Drive, it is like a cylinder ===> bad***

Did ever someone ask for the dimensions (for verification) personally?

[email protected]

It isn't helpful to poke in the dark, IMHO

PS: I am not the one who want to do
« Last Edit: 08/02/2015 07:11 PM by X_RaY »

#### Rodal

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##### Re: EM Drive Developments - related to space flight applications - Thread 3
« Reply #6192 on: 08/02/2015 07:53 PM »
...So i picked a dimensionality that came from calculations (yours and me following them and I didn't catch the booboo either and that's on me) and reported high thrusts and built it. I was wrong and you were wrong, it happens. ...
Nope.  There was no "booboo" and there was not something "wrong" in my previous selection of dimensions for Yang.  Those dimensions are the correct dimensions if one assumes that Yang selected her small diameter to be at the waveguide cut-off frequency, following Shawyer's prescription.
...
Yang's frustum has the following dimensions:
- cavity length (m): 0.24
- big diameter (m): 0.201
- small diameter (m): 0.1492
...
...the cutoff dimension, just below the guide wavelength for TE01 mode at 2.45GHz = 148.7 mm..

Proof that I selected those Yang's dimensions based on the assumption that she followed Shawyer's prescription for the small diameter to be at the cut-off frequency:

Known input:

Mode Shape: TE012
Frequency: 2.45 GHz
Table of Bessel zeros and Bessel Derivative zeros: http://wwwal.kuicr.kyoto-u.ac.jp/www/accelerator/a4/besselroot.htmlx

____________________________________________________
Proof:

Equation for cut-off diameter:
Ds = (X'01 *c)/(Pi*frequency)
=(3.83170597020751*299792458 m/s)/(Pi*2.45*10^9 1/s)
=0.1492 m

QED.  Thus the cut-off diameter for TE012 at 2.45GHz is exactly 0.1492 m and that's where the previous dimensions I selected came from.

____________________________________________________
____________________________________________________

The dimensions for Yang's EM Drive that I have placed now in the Wiki are based instead on the cone half-angle in Yang's drawings.  There is only free parameter one can choose: for example that she chose Ds based on the cut-off frequency, or that the cone half-angle is known.  One free-parameter.  That's it.  The cone half-angle in her drawings is in conflict with the assumption that her small diameter was chosen based on cut-off frequencies.  The present dimensions based on the cone half-angle in her drawings are in agreement with:

1) similar cone-half angles as NASA and Shawyer
2) in much closer agreement with the formulas from Shawyer. McCulloch and Notsosureofit for thrust

I see no violence in the fact that Yang may not be ascribing to Shawyer's prescription for a cut-off based on waveguides.  The reason I see no violence is based on the fact that Yang does NOT use Shawyer's theory.  Yang used a Finite Element Program to calculate the stresses in the EM Drive, and therefore calculate the forces.   It makes perfect sense to me that when she calculated the stresses (and therefore the resonance of the electromagnetic fields) she was cognizant of the fact (obvious to anyone performing a FEA solution) that there is no such thing as a sharp cut-off frequency, and thus she was free to choose a smaller diameter for the small base.

Those insisting on a sharp cut-off frequency do so at their peril: since such an assumption may preclude them from achieving higher thrust and higher thrust/InputPower.
« Last Edit: 08/02/2015 08:30 PM by Rodal »

#### X_RaY

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##### Re: EM Drive Developments - related to space flight applications - Thread 3
« Reply #6193 on: 08/02/2015 08:08 PM »
...So i picked a dimensionality that came from calculations (yours and me following them and I didn't catch the booboo either and that's on me) and reported high thrusts and built it. I was wrong and you were wrong, it happens. ...
Nope.  There was no "booboo" and there was not something "wrong" in my previous selection of dimensions for Yang.  Those dimensions are the correct dimensions if one assumes that Yang selected her small diameter to be at the waveguide cut-off frequency, following Shawyer's prescription.
...
Yang's frustum has the following dimensions:
- cavity length (m): 0.24
- big diameter (m): 0.201
- small diameter (m): 0.1492
...
...the cutoff dimension, just below the guide wavelength for TE01 mode at 2.45GHz = 148.7 mm..

Proof that I selected those Yang's dimensions based on the assumption that she followed Shawyer's prescription for the small diameter to be at the cut-off frequency:

Known input:

Mode Shape: TE012
Frequency: 2.45 GHz
Table of Bessel zeros: http://wwwal.kuicr.kyoto-u.ac.jp/www/accelerator/a4/besselroot.htmlx

____________________________________________________
Proof:

Equation for cut-off diameter:
Ds = (X'01 *c)/(Pi*frequency)
=(3.83170597020751*299792458 m/s)/(Pi*2.45*10^9 1/s)
=0.1492 m

QED.  Thus the cut-off diameter for TE012 at 2.45GHz is exactly 0.1492 m and that's where the previous dimensions I selected came from.

____________________________________________________
____________________________________________________

The dimensions for Yang's EM Drive that I have placed now in the Wiki are based instead on the cone half-angle in Yang's drawings.  There is only free parameter one can choose: for example that she chose Ds based on the cut-off frequency, or that the cone half-angle is known.  One free-parameter.  That's it.  The cone half-angle in her drawings is in conflict with the assumption that her small diameter was chosen based on cut-off frequencies.  The present dimensions based on the cone half-angle in her drawings are in agreement with:

1) similar cone-half angles as NASA and Shawyer
2) in much closer agreement with the formulas from Shawyer. McCulloch and Notsosureofit for thrust
How sure are you about the 0.240m length?
If you think that's it we have all together

#### flux_capacitor

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##### Re: EM Drive Developments - related to space flight applications - Thread 3
« Reply #6194 on: 08/02/2015 08:13 PM »
How sure are you about the 0.240m length?
If you think that's it we have all together
See table 1 in the Yang 2010 paper.

#### Rodal

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##### Re: EM Drive Developments - related to space flight applications - Thread 3
« Reply #6195 on: 08/02/2015 08:14 PM »
...
How sure are you about the 0.240m length?
If you think that's it we have all together
240 mm is the length that Prof. Yang explicitly gives for her EM Drive at TE012 at 2.45 Ghz in page 811, Table 1, of her paper (in Chinese)

2010年t2月   第28卷第6期

Journal of Northwestern Polytechnical University
Dec． 2010  V01．28 No．6

http://www.emdrive.com/NWPU2010paper.pdf
« Last Edit: 08/02/2015 08:15 PM by Rodal »

#### X_RaY

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##### Re: EM Drive Developments - related to space flight applications - Thread 3
« Reply #6196 on: 08/02/2015 08:16 PM »
...So i picked a dimensionality that came from calculations (yours and me following them and I didn't catch the booboo either and that's on me) and reported high thrusts and built it. I was wrong and you were wrong, it happens. ...
Nope.  There was no "booboo" and there was not something "wrong" in my previous selection of dimensions for Yang.  Those dimensions are the correct dimensions if one assumes that Yang selected her small diameter to be at the waveguide cut-off frequency, following Shawyer's prescription.
...
Yang's frustum has the following dimensions:
- cavity length (m): 0.24
- big diameter (m): 0.201
- small diameter (m): 0.1492
...
...the cutoff dimension, just below the guide wavelength for TE01 mode at 2.45GHz = 148.7 mm..

Proof that I selected those Yang's dimensions based on the assumption that she followed Shawyer's prescription for the small diameter to be at the cut-off frequency:

Known input:

Mode Shape: TE012
Frequency: 2.45 GHz
Table of Bessel zeros: http://wwwal.kuicr.kyoto-u.ac.jp/www/accelerator/a4/besselroot.htmlx

____________________________________________________
Proof:

Equation for cut-off diameter:
Ds = (X'01 *c)/(Pi*frequency)
=(3.83170597020751*299792458 m/s)/(Pi*2.45*10^9 1/s)
=0.1492 m

QED.  Thus the cut-off diameter for TE012 at 2.45GHz is exactly 0.1492 m and that's where the previous dimensions I selected came from.

____________________________________________________
____________________________________________________

The dimensions for Yang's EM Drive that I have placed now in the Wiki are based instead on the cone half-angle in Yang's drawings.  There is only free parameter one can choose: for example that she chose Ds based on the cut-off frequency, or that the cone half-angle is known.  One free-parameter.  That's it.  The cone half-angle in her drawings is in conflict with the assumption that her small diameter was chosen based on cut-off frequencies.  The present dimensions based on the cone half-angle in her drawings are in agreement with:

1) similar cone-half angles as NASA and Shawyer
2) in much closer agreement with the formulas from Shawyer. McCulloch and Notsosureofit for thrust

SD=0.1492m
BD=0.200m
L=0.240m
f_res(TE012)=~2,4537GHz
angle=6,041deg

with SD 0.15m i get 2,4490GHz
angle=5,946deg
« Last Edit: 08/02/2015 08:21 PM by X_RaY »

#### Rodal

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##### Re: EM Drive Developments - related to space flight applications - Thread 3
« Reply #6197 on: 08/02/2015 08:18 PM »
...
Did ever someone ask for the dimensions (for verification) personally?

[email protected]

It isn't helpful to poke in the dark, IMHO

PS: I am not the one who want to do

Several people have asked (Ref: NSF threads 1 and 2).  No answers have been reported.  Ever.

It has been reported Prof. Yang told a Scientific News reporter that "publicity about her EM Drive research is most unwelcome"

« Last Edit: 08/02/2015 08:23 PM by Rodal »

#### Rodal

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##### Re: EM Drive Developments - related to space flight applications - Thread 3
« Reply #6198 on: 08/02/2015 08:22 PM »
...
If you think that's it we have all together

SD=0.1492m
BD=0.200m
L=0.240m
f_res(TE012)=~2,4537GHz
angle=6,041deg

with SD 0.15m i get 2,4490GHz
angle=5,946deg

Thank you.  Confirmed:

1) There was no "booboo"

2) Your computer program agrees quite well with my computer program (once again).  TheTraveller's program  is only off by 2%, a difference which I consider to be an utterly negligible difference when we are talking about much larger differences here.  The calculations by TheTraveller are quite acceptable for engineering purposes.
« Last Edit: 08/02/2015 08:26 PM by Rodal »

#### X_RaY

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##### Re: EM Drive Developments - related to space flight applications - Thread 3
« Reply #6199 on: 08/02/2015 08:30 PM »
...
Did ever someone ask for the dimensions (for verification) personally?

[email protected]

It isn't helpful to poke in the dark, IMHO

PS: I am not the one who want to do

Several people have asked (Ref: NSF threads 1 and 2).  No answers have been reported.  Ever.

It has been reported Prof. Yang told a Scientific News reporter that "publicity about her EM Drive research is most unwelcome"
no answer?  bad scientist*

*don't know, how much the cn government got hands over their scientific results
« Last Edit: 08/02/2015 08:36 PM by X_RaY »

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