### Author Topic: EM Drive Developments - related to space flight applications - Thread 2  (Read 2482838 times)

#### Rodal

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##### Re: EM Drive Developments - related to space flight applications - Thread 2
« Reply #3220 on: 05/13/2015 03:17 PM »
...
My intention has been made clear, to openly share everything I learn and experience during my journey to replicate the Shawyer Teeter-Totter balance beam test rig and the Flight Thruster.

When given a new equation for the EM Drive, I will write an Excel spreadsheet to allow all variables to be varied, observe the results and try to learn about how this device works. Which is what I did with your equation, and discovered there appears to be a optional frequency that gives the highest Df for a fixed set of cavity dimensions.

Further to what I learned from Shawyer, I have verified your equation does conditionally match what Shawyer claims for his Df.

Big diameter matches small diameter, Df = 0. Frequency and length variation have no effect.

Very large big diameter AND very long length, Df = 1, when small diameter matches frequency wavelength. When small diameter is larger than wavelength Df < 1, when small diameter is less than wavelength Df > 1. I note Shawyer did not mention than cavity length would have an effect on Df at this boundary condition but it does.

I'm not here to score points nor take sides. I will follow the data to where it leads me, will safely replicate the Flight Thruster and openly share that journey. I do appreciate your assistance in providing your Df equation and further thoughts.

Peace.
A) Since you are appreciative of my efforts in "reading the tea leaves" from Shawyer's papers  ,  as a helpful, and further elucidating point, one of the critical variables that Shawyer did not explicitly define in his Design Factor equation variables in his papers is the cut-off frequency.  As previously discussed in the forum (in my exchanges with @aero). The equation I provided you takes:

cutOffWavelength = 2*cavityLength

This is where the cavity length comes from in the expression I provided you.

I can also provide you with an equation with any other definition for the cutOffWavelength you may prefer, for example based on the small diameter's or the big diameter's dimension.  However in that case, you will be faced with two conundrums:

1) are you assuming that the longest length (suitably multiplied by the appropriate factor) is the cavityLength or the big diameter?  (if both could occur then two expressions for the cutOffWavelength need to be computed and an IF statement to decide on the correct cutOffWavelength)

2) the correct cutOffWavelength for a truncated cone depends on the exact solution functions  (*): spherical Bessel function and associated Legendre functions eigenvalue solutions, which would result in an equation that you would not be able to model with Excel.  Based on my reading of Shawyer's papers it is apparent that Shawyer's solution is not an exact solution based on spherical Bessel functions and associated Legendre functions but is instead based on elementary functions used as an approximation over an undefined range.

B) I can also provide with a closed-form equation (that you can calculate quickly in Excel) that gives the frequency at which the Design Factor blows up and goes to infinity (instead of having to numerically approximate this frequency).  Please let me know whether this would be useful to you.

(*) for a perfect cylinder, there is only one eigenvalue problem, which is readily solved in terms of the cylindrical Bessel function zeros Xmn and  X'mn, and closed-form expressions can be given for the cutoff frequency in terms of given mode shapes, see http://en.wikipedia.org/wiki/Cutoff_frequency#Waveguides
« Last Edit: 05/13/2015 03:43 PM by Rodal »

#### rrb6699

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##### Re: EM Drive Developments - related to space flight applications - Thread 2
« Reply #3221 on: 05/13/2015 03:23 PM »
wouldn't a logical place to start be at 180 Degrees
out-of-phase then vary it from there to see if a sweet spot exists?
rr

#### TheTraveller

##### Re: EM Drive Developments - related to space flight applications - Thread 2
« Reply #3222 on: 05/13/2015 03:46 PM »
...
My intention has been made clear, to openly share everything I learn and experience during my journey to replicate the Shawyer Teeter-Totter balance beam test rig and the Flight Thruster.

When given a new equation for the EM Drive, I will write an Excel spreadsheet to allow all variables to be varied, observe the results and try to learn about how this device works. Which is what I did with your equation, and discovered there appears to be a optional frequency that gives the highest Df for a fixed set of cavity dimensions.

Further to what I learned from Shawyer, I have verified your equation does conditionally match what Shawyer claims for his Df.

Big diameter matches small diameter, Df = 0. Frequency and length variation have no effect.

Very large big diameter AND very long length, Df = 1, when small diameter matches frequency wavelength. When small diameter is larger than wavelength Df < 1, when small diameter is less than wavelength Df > 1. I note Shawyer did not mention than cavity length would have an effect on Df at this boundary condition but it does.

I'm not here to score points nor take sides. I will follow the data to where it leads me, will safely replicate the Flight Thruster and openly share that journey. I do appreciate your assistance in providing your Df equation and further thoughts.

Peace.
A) Since you are appreciative of my efforts in "reading the tea leaves" from Shawyer's papers  ,  as a helpful, and further elucidating point, one of the critical variables that Shawyer did not explicitly define in his Design Factor equation variables in his papers is the cut-off frequency.  As previously discussed in the forum (in my exchanges with @aero). The equation I provided you takes:

cutOffWavelength = 2*cavityLength

This is where the cavity length comes from in the expression I provided you.

I can also provide you with an equation with any other definition for the cutOffWavelength you may prefer, for example based on the small diameter's or the big diameter's dimension.  However in that case, you will be faced with two conundrums:

1) are you assuming that the longest length (suitably multiplied by the appropriate factor) is the cavityLength or the big diameter?  (if both could occur then two expressions for the cutOffWavelength need to be computed and an IF statement to decide on the correct cutOffWavelength)

2) the correct cutOffWavelength for a truncated cone depends on the exact solution functions  (*): spherical Bessel function and associated Legendre functions eigenvalue solutions, which would result in an equation that you would not be able to model with Excel.  Based on my reading of Shawyer's papers it is apparent that Shawyer's solution is not an exact solution based on spherical Bessel functions and associated Legendre functions but is instead based on elementary functions used as an approximation over an undefined range.

B) I can also provide with a closed-form equation (that you can calculate quickly in Excel) that gives the frequency at which the Design Factor blows up and goes to infinity (instead of having to numerically approximate this frequency).  Please let me know whether this would be useful to you.

(*) for a perfect cylinder, there is only one eigenvalue problem, which is readily solved in terms of the cylindrical Bessel function zeros Xmn and  X'mn, and closed-form expressions can be given for the cutoff frequency in terms of given mode shapes, see http://en.wikipedia.org/wiki/Cutoff_frequency#Waveguides

Appreciate the reply. Lets wait to see if Shawyer decided to help us stop needing to read tea leaves.

This may be useful information:

Quote
As a start to understanding the microwave engineering needed to design a successful EmDrive cavity I recommend:

Microwave Engineering Passive Circuits

Peter A. Rizzi

Prentice Hall 1988

ISBN 0-13-586702-9 025

This will enable you to calculate the guide wavelengths for your proposed cavity geometry, resonant frequency and mode. You can then develop a numerical model to integrate incremental guide wavelengths to arrive at an accurate set of dimensions.

If you use a commercial  finite element software package as a design aid, make sure it can cope with close to cut-off conditions. Most are hopelessly inaccurate and will even give an answer at dimensions below cut-off.

Good luck

Roger Shawyer

Quote

Hi

The derivation of my Design Factor is given in: The EmDrive - A New Satellite Propulsion Technology. This paper was presented at the “2nd Conference on Disruptive Technology in Space Activities” in Toulouse 2010, which I have attached.

As you can see the equation contains the guide wavelength terms for both ends of the cavity. The solution of these terms depends on waveguide type, dimensions, frequency and mode and can be found in any good microwave engineering text book such as the one I recommended to you.

As you will discover the solutions to the guide wavelength terms are very non-linear, which makes the accurate design of a tapered cavity particularly difficult. At SPR Ltd we have developed our own software to give a 2D high resolution numerical solution to the problem. This proprietary design software has been validated for a number of different cavities by ourselves, as well as different research groups operating under commercial agreements with SPR Ltd.

To answer your particular question about operating below cut-off, in these conditions the guide wavelength goes to infinity. As you can see from my equation, this is one reason why the value of the design factor is constrained between 0 and 1.

Best regards

Roger.

So we need to design for Df slightly < 1.0.
« Last Edit: 05/13/2015 03:51 PM by TheTraveller »
It Is Time For The EmDrive To Come Out Of The Shadows

#### SeeShells

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##### Re: EM Drive Developments - related to space flight applications - Thread 2
« Reply #3223 on: 05/13/2015 03:50 PM »
...

Best Regards,
Todd

Barely able to keep pace Todd...its a good thing. maximizing asymmetry in attenuation different from absorption like the stuff I used to work with?

http://www.westernrubber.com/products/himag-microwave-absorbers/himag-cavity-resonance-absorbers/

It is getting pretty hot and heavy in here and I'm not sure I am keeping up either. Love it though.
I've been mulling around the ideas of harmonics and wondered if anyone has considered injecting 2 RF sources into the cavity,
One set and the other variable in frequency? I've been slowly working my way through this but like I said it's been slow. I welcome and inputs and thoughts.

Maybe first try to state what kind of nonlinear coupling effects could be at play to make a difference ? Linear system => result(wave1+wave2)=result(wave1)+result(wave2) so doing wave1+wave2 would bring nothing new, qualitatively, without a mechanism to explain result(single wave)!=0 in the first place...

Kudos to SeeShells !!!!!  (do we need more hot and heavy weather to keep producing these great suggestions    )

This from this paper recently brought up by Todd (hat tip to WarpTech), which confirms the validity of SeeShells suggestion:

Attenuation in Rectangular Waveguides with Finite Conductivity Walls
Kim Ho YEAP, Choy Yoong THAM, Ghassan YASSIN, Kee Choon YEONG
RADIOENGINEERING, VOL. 20, NO. 2, JUNE 2011

Quote from: Kim Ho YEAP, Choy Yoong THAM, Ghassan YASSIN, Kee Choon YEONG
An important consequence of this
work is the demonstration that the loss computed for degenerate
modes propagating simultaneously is not simply
In other words, the combined loss of two co-existing
modes is higher than adding the losses of two modes
propagating independently. This can be explained by the
mode coupling effects, which is significant when the phase
constants of two propagating modes are different yet very
close.
Thanks. You guys are good!
All I was doing was sitting and relaxing in my hot tub (ok ok I had a cold one going too) imagining and visualizing the 2 waves in the EM container and seeing the mixing of the waves. I saw the additive factors and the losses and it looked like it might work well, but when added in the idea that to really work I needed to include what Mulletron threw at me (big kudos to him) the PTFE material you used and the properties of it to attenuate the signals I decided it was to much info and needed more time or another cold one.

#### Rodal

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##### Re: EM Drive Developments - related to space flight applications - Thread 2
« Reply #3224 on: 05/13/2015 03:54 PM »
...
This may be useful information:

Quote
As a start to understanding the microwave engineering needed to design a successful EmDrive cavity I recommend:

Microwave Engineering Passive Circuits

Peter A. Rizzi

Prentice Hall 1988

ISBN 0-13-586702-9 025

This will enable you to calculate the guide wavelengths for your proposed cavity geometry, resonant frequency and mode. You can then develop a numerical model to integrate incremental guide wavelengths to arrive at an accurate set of dimensions.

If you use a commercial  finite element software package as a design aid, make sure it can cope with close to cut-off conditions. Most are hopelessly inaccurate and will even give an answer at dimensions below cut-off.

Good luck

Roger Shawyer
Again, Shawyer does not answer directly: he does not provide his equation for the Design Factor, and neither does he define the variables thereof.

Quote
What was expected from Shawyer, the author of the equation, is to produce his equation: to answer "this is my equation:..." (defining the Design Factor and its variables, and not resorting to references where the variables are not explicitly defined).

As I pointed out in my prior message http://forum.nasaspaceflight.com/index.php?topic=36313.msg1373671#msg1373671  the main issue is a definition for the cut-off frequency in Shawyer's design factor.  Shawyer does not give you an equation for the cutoff-frequency either.

As Shawyer signs in his message:  "Good Luck"

(Good luck, I suppose in ever finding out what is an explicit equation for Shawyer's Design Factor that you can program in Excel  )

« Last Edit: 05/13/2015 04:43 PM by Rodal »

#### SeeShells

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##### Re: EM Drive Developments - related to space flight applications - Thread 2
« Reply #3225 on: 05/13/2015 04:25 PM »
...

Best Regards,
Todd

Barely able to keep pace Todd...its a good thing. maximizing asymmetry in attenuation different from absorption like the stuff I used to work with?

http://www.westernrubber.com/products/himag-microwave-absorbers/himag-cavity-resonance-absorbers/

It is getting pretty hot and heavy in here and I'm not sure I am keeping up either. Love it though.
I've been mulling around the ideas of harmonics and wondered if anyone has considered injecting 2 RF sources into the cavity,
One set and the other variable in frequency? I've been slowly working my way through this but like I said it's been slow. I welcome and inputs and thoughts.

Maybe first try to state what kind of nonlinear coupling effects could be at play to make a difference ? Linear system => result(wave1+wave2)=result(wave1)+result(wave2) so doing wave1+wave2 would bring nothing new, qualitatively, without a mechanism to explain result(single wave)!=0 in the first place...

Kudos to SeeShells !!!!!  (do we need more hot and heavy weather to keep producing these great suggestions    )

This from this paper recently brought up by Todd (hat tip to WarpTech), which confirms the validity of SeeShells suggestion:

Attenuation in Rectangular Waveguides with Finite Conductivity Walls
Kim Ho YEAP, Choy Yoong THAM, Ghassan YASSIN, Kee Choon YEONG
RADIOENGINEERING, VOL. 20, NO. 2, JUNE 2011

Quote from: Kim Ho YEAP, Choy Yoong THAM, Ghassan YASSIN, Kee Choon YEONG
An important consequence of this
work is the demonstration that the loss computed for degenerate
modes propagating simultaneously is not simply
In other words, the combined loss of two co-existing
modes is higher than adding the losses of two modes
propagating independently. This can be explained by the
mode coupling effects, which is significant when the phase
constants of two propagating modes are different yet very
close.
Thanks. You guys are good!
All I was doing was sitting and relaxing in my hot tub (ok ok I had a cold one going too) imagining and visualizing the 2 waves in the EM container and seeing the mixing of the waves. I saw the additive factors and the losses and it looked like it might work well, but when added in the idea that to really work I needed to include what Mulletron threw at me (big kudos to him) the PTFE material you used and the properties of it to attenuate the signals I decided it was to much info and needed more time or another cold one.
I've got to be somewhere so I just quickly scanned the paper and it looks very good. I dig into it latter.  Big Thanks Rodal!

#### zellerium

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##### Re: EM Drive Developments - related to space flight applications - Thread 2
« Reply #3226 on: 05/13/2015 04:29 PM »
Zellerium

In relation to your proposed replication I remember originally mentioning a curved mirror. I was doing some microcontroller work today and now think this is not what you need for this particular experiment.  The curved mirror is just a visual display device, as you will be aware it just accentuates the reflected angle of the laser, good for viewing movement but that is about all at this particular level of usage.

What would be good is an ordinary plane/flat mirror, but DONT mount it on top of the replication.
If it is on top then due to the 2 attached strings to the roof, the device will move forward BUT also due to it hanging at the bottom of a "circle" the device will move slightly upwards. This results in the mirror moving both forward and up with the effect that the lasers beam will not correctly traverse the line you want.

Place the mirror on the rear of the replication such that the laser is pointed horizontally (not vertically) at the mirror. It will strike the mirror and reflect onto the rear wall. eg mirror at 45 degree to the replication body with the mirrored side facing towards you (and outer edge back at 45) looking horizontally at the experiment. The expected line of laser traversal is horizontal.

This allows the mirror to move forwards and up as before but the upwards movement wont impact the movement/accuracy of the laser as much as before.

Ideally if you could obtain (or borrow) some light triggered timers/counters, and arrange them with equal spacing "straight" along the projected path of the beam (push the unit gently by hand initially to observe the actual path). The timers are connected to a single-trigger-unit that starts ALL the timers Simultaneously as the beam crosses the initial "start" LDR switch., then the beams path will activate each timers LDR (Light Dependent Resistor or Light Dependent Diode) to stop each timer as the beam crosses each detectors face. From there you have counts of time, difference between timer units (acceleration or constant momentum?), average velocity etc.

Arc:

Thank you for taking the time to think about our setup. I agree that a vertical mirror will be a better choice, I hadn't considered the difference between the x and y displacements. Shouldn't be a problem to implement.

As for the light dependent diode, I like the idea! We have been talking to a computer engineer who wants to shoot the laser directly into a camera to measure the change in its position. He can write a program that finds a baseline and hopefully will be able to detect very small changes in position, and perhaps also time its trajectory to detemine momentum. But this momentum measurement might be limited by the fps of the camera?

Looking at the force plots from EW tells me this force is relatively constant (so long as our power supply is) and the pendulum will settle at a different equilibrium position fairly quickly.

What do you think of the camera idea?

Kurt Zeller

#### jordan.greenhall

##### Re: EM Drive Developments - related to space flight applications - Thread 2
« Reply #3227 on: 05/13/2015 04:32 PM »
Hi everyone, this is a notification that there is a new thread here http://forum.nasaspaceflight.com/index.php?topic=37563.0 specifically focused on an X-prize for the EM Drive. If you are interested in helping out, please come and join us.

#### TheTraveller

##### Re: EM Drive Developments - related to space flight applications - Thread 2
« Reply #3228 on: 05/13/2015 04:38 PM »
...
This may be useful information:

Quote
As a start to understanding the microwave engineering needed to design a successful EmDrive cavity I recommend:

Microwave Engineering Passive Circuits

Peter A. Rizzi

Prentice Hall 1988

ISBN 0-13-586702-9 025

This will enable you to calculate the guide wavelengths for your proposed cavity geometry, resonant frequency and mode. You can then develop a numerical model to integrate incremental guide wavelengths to arrive at an accurate set of dimensions.

If you use a commercial  finite element software package as a design aid, make sure it can cope with close to cut-off conditions. Most are hopelessly inaccurate and will even give an answer at dimensions below cut-off.

Good luck

Roger Shawyer
Again, Shawyer does not answer directly: he does not provide his equation for the Design Factor, and neither does he define the variables thereof.

Quote
What was expected from Shawyer, the author of the equation, is to produce his equation: to answer "this is my equation:..." (defining the Design Factor and its variables, and not resorting to references where the variables are not explicitly defined).

As I pointed out in my prior message http://forum.nasaspaceflight.com/index.php?topic=36313.msg1373671#msg1373671  the main issue is a definition for the cut-off frequency in Shawyer's design factor.  Shawyer does not give you an equation for the cutoff-frequency either.

As Shawyer signs in his message:  "Good Luck"

(Good luck, I suppose in ever finding out what is an explicit equation for Shawyer's Design Factor that you can program in Excel  )

As to Shawyer's response:

Quote
At SPR Ltd we have developed our own software to give a 2D high resolution numerical solution to the problem. This proprietary design software has been validated for a number of different cavities by ourselves, as well as different research groups operating under commercial agreements with SPR Ltd.

That is not an answer to your question, which was what is the formula for the Design Factor.  As a counterexample, I have a full 3D exact solution to the truncated cone for arbitrary mode shapes, in Mathematica, that is proprietary to me. That is useful to me, and of no use to anybody else (it can only be of some use to the extent that I release particular numerical solutions and images, but it is of no help to you in programming the Design Factor in Excel)     .

I appreciate SPR is in business and maybe giving away too much info is not in their best interest. I asked but did not receive all of what I asked for. I'm appreciative of the info Shawyer has shared. I'll follow his bread crumbs and see what I can come up with.

I have started to learn microwave waveguide theory and application. Lots of info on the net. I learn quick. From my read of Shawyers equations, just with an hour of microwave waveguide research, I'm starting to see where is he going and why.

End result is I will have a version of the SPR Flight Thruster, variable Rf frequency generator and variable power amp working on a knife edge Teeter Totter test rig. I expect it will teach me a lot and fill in any holes.
It Is Time For The EmDrive To Come Out Of The Shadows

#### TheTraveller

##### Re: EM Drive Developments - related to space flight applications - Thread 2
« Reply #3229 on: 05/13/2015 04:49 PM »
Hi everyone, this is a notification that there is a new thread here http://forum.nasaspaceflight.com/index.php?topic=37563.0 specifically focused on an X-prize for the EM Drive. If you are interested in helping out, please come and join us.

My comment:
http://forum.nasaspaceflight.com/index.php?topic=37563.msg1373714#msg1373714
It Is Time For The EmDrive To Come Out Of The Shadows

#### Rodal

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##### Re: EM Drive Developments - related to space flight applications - Thread 2
« Reply #3230 on: 05/13/2015 04:54 PM »
....

My comment:
http://forum.nasaspaceflight.com/index.php?topic=37563.msg1373714#msg1373714

« Last Edit: 05/13/2015 05:00 PM by Rodal »

#### zen-in

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##### Re: EM Drive Developments - related to space flight applications - Thread 2
« Reply #3231 on: 05/13/2015 04:55 PM »
Zellerium

In relation to your proposed replication I remember originally mentioning a curved mirror. I was doing some microcontroller work today and now think this is not what you need for this particular experiment.  The curved mirror is just a visual display device, as you will be aware it just accentuates the reflected angle of the laser, good for viewing movement but that is about all at this particular level of usage.

What would be good is an ordinary plane/flat mirror, but DONT mount it on top of the replication.
If it is on top then due to the 2 attached strings to the roof, the device will move forward BUT also due to it hanging at the bottom of a "circle" the device will move slightly upwards. This results in the mirror moving both forward and up with the effect that the lasers beam will not correctly traverse the line you want.

Place the mirror on the rear of the replication such that the laser is pointed horizontally (not vertically) at the mirror. It will strike the mirror and reflect onto the rear wall. eg mirror at 45 degree to the replication body with the mirrored side facing towards you (and outer edge back at 45) looking horizontally at the experiment. The expected line of laser traversal is horizontal.

This allows the mirror to move forwards and up as before but the upwards movement wont impact the movement/accuracy of the laser as much as before.

Ideally if you could obtain (or borrow) some light triggered timers/counters, and arrange them with equal spacing "straight" along the projected path of the beam (push the unit gently by hand initially to observe the actual path). The timers are connected to a single-trigger-unit that starts ALL the timers Simultaneously as the beam crosses the initial "start" LDR switch., then the beams path will activate each timers LDR (Light Dependent Resistor or Light Dependent Diode) to stop each timer as the beam crosses each detectors face. From there you have counts of time, difference between timer units (acceleration or constant momentum?), average velocity etc.

There was a lot of discussion about the EW measurement methods on pages 62 - 70 of this thread.   The actual displacement of the TP when RF power is applied is very miniscule.   The illustration below shows a calibration pulse next to the distance measurement scale.   The end of the TP has moved just 1 micrometer.    Earlier in this thread I did a rough calculation of a laser - mirror displacement measurement setup based on this small displacement:

A problem with this experiment is the extremely small displacements that indicate a thrust.   A displacement of 4 micrometers has the TP beam move through just 1.7 arcSec. of rotation.   If a laser beam was reflected off the LDS moving mirror and someone was 1 km away they would see the reflected dot move just a few mm.   The LDS is just as sensitive to angular changes of the mirror.   An experiment of this type requires repeatable, consistent results with a signal level far above what is currently seen to provide proof of this proposed theory of its operation.
« Last Edit: 05/13/2015 04:59 PM by zen-in »

#### TheTraveller

##### Re: EM Drive Developments - related to space flight applications - Thread 2
« Reply #3232 on: 05/13/2015 05:11 PM »
....

My comment:
http://forum.nasaspaceflight.com/index.php?topic=37563.msg1373714#msg1373714

This is me and how I work & live.

Been around too long. Have seen what greed does to people. I'm interested in solving the issue of does it work or not, with no theory wheel barrow to push. That is why I will follow the data and why I did what I did with your Df equation. It was an example of chasing the data to see what it says and where it leads me.

I'm rolling back the years and working through Shawyers Df and other supporting equation, while teaching myself what happens to microwaves when constrained in waveguides of various shapes and contours.
It Is Time For The EmDrive To Come Out Of The Shadows

#### zellerium

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##### Re: EM Drive Developments - related to space flight applications - Thread 2
« Reply #3233 on: 05/13/2015 05:20 PM »

There was a lot of discussion about the EW measurement methods on pages 62 - 70 of this thread.   The actual displacement of the TP when RF power is applied is very miniscule.   The illustration below shows a calibration pulse next to the distance measurement scale.   The end of the TP has moved just 1 micrometer.    Earlier in this thread I did a rough calculation of a laser - mirror displacement measurement setup based on this small displacement:

A problem with this experiment is the extremely small displacements that indicate a thrust.   A displacement of 4 micrometers has the TP beam move through just 1.7 arcSec. of rotation.   If a laser beam was reflected off the LDS moving mirror and someone was 1 km away they would see the reflected dot move just a few mm.   The LDS is just as sensitive to angular changes of the mirror.   An experiment of this type requires repeatable, consistent results with a signal level far above what is currently seen to provide proof of this proposed theory of its operation.

Is that displacement assuming we will get EW's thrust values?
If we use a microwave oven magnetron putting out 1 kW I hope we get much higher thrust values than EW who used only 17 ~ 50 W.
I see your concern, but without a low thrust torsion pendulum it seems near impossible to measure 20~100 micoNewtons
« Last Edit: 05/13/2015 05:20 PM by zellerium »

#### Rodal

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##### Re: EM Drive Developments - related to space flight applications - Thread 2
« Reply #3234 on: 05/13/2015 05:29 PM »
....

There was a lot of discussion about the EW measurement methods on pages 62 - 70 of this thread.   The actual displacement of the TP when RF power is applied is very miniscule.   The illustration below shows a calibration pulse next to the distance measurement scale.   The end of the TP has moved just 1 micrometer.    Earlier in this thread I did a rough calculation of a laser - mirror displacement measurement setup based on this small displacement:

A problem with this experiment is the extremely small displacements that indicate a thrust.   A displacement of 4 micrometers has the TP beam move through just 1.7 arcSec. of rotation.   If a laser beam was reflected off the LDS moving mirror and someone was 1 km away they would see the reflected dot move just a few mm.   The LDS is just as sensitive to angular changes of the mirror.   An experiment of this type requires repeatable, consistent results with a signal level far above what is currently seen to provide proof of this proposed theory of its operation.
What would be an acceptable displacement level for NASA EW to consistently measure with their set-up, in your view?

20 micrometers ?

Can you give us your guesstimate for an acceptable displacement threshold ?  Thanks
« Last Edit: 05/13/2015 05:30 PM by Rodal »

#### Jared

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##### Re: EM Drive Developments - related to space flight applications - Thread 2
« Reply #3235 on: 05/13/2015 05:35 PM »
....

My comment:
http://forum.nasaspaceflight.com/index.php?topic=37563.msg1373714#msg1373714

This is me and how I work & live.

Been around too long. Have seen what greed does to people. I'm interested in solving the issue of does it work or not, with no theory wheel barrow to push. That is why I will follow the data and why I did what I did with your Df equation. It was an example of chasing the data to see what it says and where it leads me.

I'm rolling back the years and working through Shawyers Df and other supporting equation, while teaching myself what happens to microwaves when constrained in waveguides of various shapes and contours.

What a great statement. For weeks now, reading this thread has been my favorite intellectual pastime (can't help you with any of the maths though, as I majored in linguistics and political science).

#### zen-in

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##### Re: EM Drive Developments - related to space flight applications - Thread 2
« Reply #3236 on: 05/13/2015 05:36 PM »

There was a lot of discussion about the EW measurement methods on pages 62 - 70 of this thread.   The actual displacement of the TP when RF power is applied is very miniscule.   The illustration below shows a calibration pulse next to the distance measurement scale.   The end of the TP has moved just 1 micrometer.    Earlier in this thread I did a rough calculation of a laser - mirror displacement measurement setup based on this small displacement:

A problem with this experiment is the extremely small displacements that indicate a thrust.   A displacement of 4 micrometers has the TP beam move through just 1.7 arcSec. of rotation.   If a laser beam was reflected off the LDS moving mirror and someone was 1 km away they would see the reflected dot move just a few mm.   The LDS is just as sensitive to angular changes of the mirror.   An experiment of this type requires repeatable, consistent results with a signal level far above what is currently seen to provide proof of this proposed theory of its operation.

Is that displacement assuming we will get EW's thrust values?
If we use a microwave oven magnetron putting out 1 kW I hope we get much higher thrust values than EW who used only 17 ~ 50 W.
I see your concern, but without a low thrust torsion pendulum it seems near impossible to measure 20~100 micoNewtons

I don't dispute the need for a low thrust torsion pendulum.  I'm just stating that a reflected laser beam can't provide the required resolution.    The measurement sensor EW used could measure small displacements with more precision than a reflected laser beam.    Microwave Oven magnetrons are hazardous and potentially lethal devices when removed from an oven.   For FCC compliance and safety reasons it should be enclosed by a 6-side Faraday cage with a power interlock.   Even that may not be enough to satisfy the FCC if interference is reported.
« Last Edit: 05/13/2015 05:55 PM by zen-in »

#### Notsosureofit

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##### Re: EM Drive Developments - related to space flight applications - Thread 2
« Reply #3237 on: 05/13/2015 05:37 PM »

There was a lot of discussion about the EW measurement methods on pages 62 - 70 of this thread.   The actual displacement of the TP when RF power is applied is very miniscule.   The illustration below shows a calibration pulse next to the distance measurement scale.   The end of the TP has moved just 1 micrometer.    Earlier in this thread I did a rough calculation of a laser - mirror displacement measurement setup based on this small displacement:

A problem with this experiment is the extremely small displacements that indicate a thrust.   A displacement of 4 micrometers has the TP beam move through just 1.7 arcSec. of rotation.   If a laser beam was reflected off the LDS moving mirror and someone was 1 km away they would see the reflected dot move just a few mm.   The LDS is just as sensitive to angular changes of the mirror.   An experiment of this type requires repeatable, consistent results with a signal level far above what is currently seen to provide proof of this proposed theory of its operation.

Is that displacement assuming we will get EW's thrust values?
If we use a microwave oven magnetron putting out 1 kW I hope we get much higher thrust values than EW who used only 17 ~ 50 W.
I see your concern, but without a low thrust torsion pendulum it seems near impossible to measure 20~100 micoNewtons

Cavendish pendulum.

#### TheTraveller

##### Re: EM Drive Developments - related to space flight applications - Thread 2
« Reply #3238 on: 05/13/2015 05:39 PM »

There was a lot of discussion about the EW measurement methods on pages 62 - 70 of this thread.   The actual displacement of the TP when RF power is applied is very miniscule.   The illustration below shows a calibration pulse next to the distance measurement scale.   The end of the TP has moved just 1 micrometer.    Earlier in this thread I did a rough calculation of a laser - mirror displacement measurement setup based on this small displacement:

A problem with this experiment is the extremely small displacements that indicate a thrust.   A displacement of 4 micrometers has the TP beam move through just 1.7 arcSec. of rotation.   If a laser beam was reflected off the LDS moving mirror and someone was 1 km away they would see the reflected dot move just a few mm.   The LDS is just as sensitive to angular changes of the mirror.   An experiment of this type requires repeatable, consistent results with a signal level far above what is currently seen to provide proof of this proposed theory of its operation.

Is that displacement assuming we will get EW's thrust values?
If we use a microwave oven magnetron putting out 1 kW I hope we get much higher thrust values than EW who used only 17 ~ 50 W.
I see your concern, but without a low thrust torsion pendulum it seems near impossible to measure 20~100 micoNewtons

If I might ask. What are your cavity dimensions to obtain cavity resonance at 2.45GHz? For the EW copper cavity dimensions, 2.45GHZ is a long way from anything that will enable the magnetron to fill the cavity with a lot of microwave energy. If you don't get cavity resonance with the magnetron frequency, do you expect to get thrust?
It Is Time For The EmDrive To Come Out Of The Shadows

#### zen-in

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##### Re: EM Drive Developments - related to space flight applications - Thread 2
« Reply #3239 on: 05/13/2015 05:47 PM »
....

There was a lot of discussion about the EW measurement methods on pages 62 - 70 of this thread.   The actual displacement of the TP when RF power is applied is very miniscule.   The illustration below shows a calibration pulse next to the distance measurement scale.   The end of the TP has moved just 1 micrometer.    Earlier in this thread I did a rough calculation of a laser - mirror displacement measurement setup based on this small displacement:

A problem with this experiment is the extremely small displacements that indicate a thrust.   A displacement of 4 micrometers has the TP beam move through just 1.7 arcSec. of rotation.   If a laser beam was reflected off the LDS moving mirror and someone was 1 km away they would see the reflected dot move just a few mm.   The LDS is just as sensitive to angular changes of the mirror.   An experiment of this type requires repeatable, consistent results with a signal level far above what is currently seen to provide proof of this proposed theory of its operation.
What would be an acceptable displacement level for NASA EW to consistently measure with their set-up, in your view?

20 micrometers ?

Can you give us your guesstimate for an acceptable displacement threshold ?  Thanks
First it needs to be established that a displacement is produced when the EW device has RF power applied to it.   Tilting and changes of the CoM due to thermal-mechanical effects could also produce the same readings.    The step response of the EW TP when high voltage DC calibration pulses are applied is very different from what is observed when RF power is applied.  We know the calibration pulses produce a displacement.     If the step response due to applied RF looked the same then that would be more proof the TP underwent a displacement when RF power was applied.    Conversely if a thermal step drive was applied to the cavity (with a DC power resistor, heating pads, or focused IR energy) and that step response had the same characteristics as the RF response there would be more evidence in the other direction.

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