Author Topic: EM Drive Developments - related to space flight applications - Thread 3  (Read 1802088 times)

Offline WarpTech

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Assuming you're right, can you write down your equation for thrust as a function of parameters that can be engineered?

The equation is already written by Egan and by Yang. What I don't have is the expressions for E and H, that are dependent on the design of the frustum. I can only say, the function will be of the form E0*e-t/T, where T will be a function dependent on the direction of the unit Normal vectors and the shape of the frustum. If you have software that can crunch Hankel functions, we could determine what they are.

Todd

Well I can crunch Hankel functions all day long.  What I don't get is how one is going to satisfy the boundary conditions for the cavity.

The geometrical attenuation equation derived by the Chinese authors is for an open waveguide, which has no standing waves.  To get standing waves one has to impose Boundary Conditions, as done for example by Egan.

What is the solution (if there is one) that has simultaneous standing waves and evanescent waves and yet it respects the boundary conditions of the problem?

Zeng and Fan obtain the attenuation γ as Hankel functions from the derivative of the Log of the Electric field for a travelling wave

If we take the derivative of the Log of the Electric field standing waves we will not get a correct expression for an evanescent wave.

Are we supposed to assume that some of the travelling waves (with a particular frequency) traveling towards the apex become evanescent waves? and other ones (at another frequency) become standing waves?

I can do that, but then how do you impose a condition that restricts what travelling waves become evanescent waves and which ones form standing waves?

I have not seen an exact solution for this problem, I'm not sure there is one. 
I have only seen solutions for whispering gallery modes coupling with evanescent waves, and some of those solutions show chaos (which is interesting because the Finite Difference numerical solutions obtained by aero did look like chaotic fractal patterns)




It may have to be solved numerically

Hence, why I said the frustum needs to be longer, so we can have something "closer" to Zeng & Fan's waveguide for traveling waves. If we are confined to 0-length past the cut-off diameter, attenuation is minimized, reflection and Q are higher. If we extend it out a full wavelength, we may attenuate 66% of the energy. The other 33% will be reflected with a larger phase shift than what Shawyer's design allows.

Also, the standing waves in a damped cavity will also frequency shift due to the damping. That's what gives Shawyer's design "some" thrust, but as I said, it is the rate of attenuation that will exert a higher force. So a longer front end to give the waves some traveling room to be attenuated faster, is what I believe is needed.

In other words, "design" the thruster more like Zeng and Fan and less like Shawyer.
Todd

Offline TheTraveller

History repeats itself. Which reminds me of Leo Szilard in the 1930'es. Skeptics need a proof first.  :(
As it looks now, it could easily happen that the Chinese will provide it...

Shawyer has stated he will release a new peer reviewed Superconducting EMDrive in 2015, created with the assistance of other companies SPR works with. He normally releases at IAC meetings. Next is mid Oct 2015.

Perhaps yes, perhaps not ?

Presentations at conferences like the IAC meetings are not what is usually meant by "peer reviewed publications". [  http://en.wikipedia.org/wiki/Peer_review  ]

I suggest Shawyer knows what peer review means. My point was if the paper is ready for release he may decide to do so at IAC 2015.
"As for me, I am tormented with an everlasting itch for things remote. I love to sail forbidden seas.
Herman Melville, Moby Dick

Offline TheTraveller

...
Maybe LOOK at the photos. Notice the really wide & thick flanges on the ends. Need to subtrace 2x the flange width, then 2mm for wall thickness from the 265mm overall width to get big end internal diameters.
OK, but Shawyer never reported the flange widths in his papers, to my knowledge.

So, what should I put in the wiki, that:

1) You guesstimated the flange widths from the photographs
or that
2) You got the internal dimensions from Shawyer?

How do you know that Shawyer used 2 mm wall thickness?

Thanks

1. Measured from latest non distorted Flight Thruster photo pixel data, knowing overall width & height.

Dont know wall thickness. Guessed at 2mm to give more thermal mass, to reduce thermally induced dimension changes.

Nothing changes much if you enter my dimensions in my spreadsheet and try various wall and flange thickness. Df stays around 0.64-0.65.

Biggie is getting end plate spacing to give TE013 resonance and know that frequency. Shawyer's 3.9003GHz was vital to check my calculator did resonance same as SPR software. Adding 0.6mm to length / spacing then give resonance at the desired 3.85GHz, which is a good back test that my dimensions are close enough. Which is what Shawyer said to me.
"As for me, I am tormented with an everlasting itch for things remote. I love to sail forbidden seas.
Herman Melville, Moby Dick

Online Rodal

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...
Maybe LOOK at the photos. Notice the really wide & thick flanges on the ends. Need to subtrace 2x the flange width, then 2mm for wall thickness from the 265mm overall width to get big end internal diameters.
OK, but Shawyer never reported the flange widths in his papers, to my knowledge.

So, what should I put in the wiki, that:

1) You guesstimated the flange widths from the photographs
or that
2) You got the internal dimensions from Shawyer?

How do you know that Shawyer used 2 mm wall thickness?

Thanks

1. Measured from latest non distorted Flight Thruster photo pixel data, knowing overall width & height.

Dont know wall thickness. Guessed at 2mm to give more thermal mass, to reduce thermally induced dimension changes.

Nothing changes much if you enter my dimensions in my spreadsheet and try various wall and flange thickness. Df stays around 0.64-0.65.

Biggie is getting end plate spacing to give TE013 resonance and know that frequency. Shawyer's 3.9003GHz was vital to check my calculator did resonance same as SPR software. Adding 0.6mm to length / spacing then give resonance at the desired 3.85GHz, which is a good back test that my dimensions are close enough. Which is what Shawyer said to me.
Thanks, that's useful.  I did put your dimensions in the EM Drive wiki.  I will also link to your response for people interested in the reasons for the numbers.

Offline rfmwguy

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Thought experiment time...2 minute time-out:

Grazing on the massive amount of theories and equations here brought me to a brick wall. Then I read this paper:

Entropic Accelerating Universe: http://arxiv.org/pdf/1002.4278v3

"...Dark energy is thereby obviated and the acceleration is due to an entropic force naturally arising from the information storage on the horizon surface screen."

I am becoming convinced that our lack of understanding of the other 95% of the universe is what is causing our difficulties. If the EM Drive is real, I am proposing it is being pushed by natural force we call entropy. How the frustum is resonating/responding to it is beyond me. Perhaps the photonic energy is projected on the small end of the frustum and natural entropy, alone is responsible for movement.

It is "sailing on entropy", radiating naturally from any reference frame we choose in space-time...Only when it somehow becomes "opaque" to it. No CoE/M difficulties. Its not a violation, but an expansion of what we consider "normal" forces...the other 70%.

We now return you to our previously scheduled discussion. ;)




Offline rfmwguy

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Thought experiment time...2 minute time-out:

Grazing on the massive amount of theories and equations here brought me to a brick wall. Then I read this paper:

Entropic Accelerating Universe: http://arxiv.org/pdf/1002.4278v3

"...Dark energy is thereby obviated and the acceleration is due to an entropic force naturally arising from the information storage on the horizon surface screen."

I am becoming convinced that our lack of understanding of the other 95% of the universe is what is causing our difficulties. If the EM Drive is real, I am proposing it is being pushed by natural force we call entropy. How the frustum is resonating/responding to it is beyond me. Perhaps the photonic energy is projected on the small end of the frustum and natural entropy, alone is responsible for movement.

It is "sailing on entropy", radiating naturally from any reference frame we choose in space-time...Only when it somehow becomes "opaque" to it. No CoE/M difficulties. Its not a violation, but an expansion of what we consider "normal" forces...the other 70%.

We now return you to our previously scheduled discussion. ;)

OK, and how do we explain that we have not seen other microwave cavities being pushed before? 
Are these forces also present in asymmetric mobile phones ?
What is particular about the EM Drive?

Of the hundreds of cavities, I've been around, tuned and generally treated like a rented mule  ;) I've never seen anything like a Frustum in use. Even if I've had, most resonant cavities top out at 500 watts max input below 1 GHz and any force would be miniscule and unnoticed...because no one is looking for it.

I think the Frustum is the key, not the frequency, and not (directly) the power. If the special propogation of EM against the small end is creating something that the force of Entropy recognizes, I am not certain, but believe it is possible.

All I know is we cannot measure entropy directly, only the distant objects in the universe speeding up. A sort of antithesis to a gravitational force which collects around matter. Entropy does not seem to care about mass either on the micro or macro scale. Entropy acts on everything. Generally speaking the larger the mass is, the faster entropy works.

Offline TheTraveller

I'm currently in bed, dealing with a few long term health issues. Not much EMDrive build work will happen by me for 4 weeks or so.

Will try to check the forum at least twice a day.

Wish the other EMDrive replicators and experimenters all the best results in working out how to get us off this rock, using other thrust generation methods than long, controlled & directed explosions.
« Last Edit: 06/11/2015 10:58 PM by TheTraveller »
"As for me, I am tormented with an everlasting itch for things remote. I love to sail forbidden seas.
Herman Melville, Moby Dick

Offline deltaMass

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@TheTraveller: get well soon!

Online Rodal

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I'm currently in bed, dealing with a few long term health issues. Not much EMDrive build work will happen by me for 4 weeks or so.

Will try to check the forum at least twice a day.

Wish the other EMDrive replicators and experimenters all the best results in working out how to get us off this rock, using other thrust generation methods than long, controlled & directed explosions.
Wishing you all the best and that you can use this time to re-charge.  Hope your recovery is a speedy one

Offline deltaMass

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@rfmwguy: If it's that esoteric, then perhaps a frustum is not an optimal shape. Perhaps the sidewalls need to follow some esoteric functional profile, as perhaps also do the end plates. But there's no way to get a handle on that sort of speculation without some hard mathematics behind your idea.

Offline Star One

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I'm currently in bed, dealing with a few long term health issues. Not much EMDrive build work will happen by me for 4 weeks or so.

Will try to check the forum at least twice a day.

Wish the other EMDrive replicators and experimenters all the best results in working out how to get us off this rock, using other thrust generation methods than long, controlled & directed explosions.

Sorry to hear that get well soon.

Offline SeeShells

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I'm currently in bed, dealing with a few long term health issues. Not much EMDrive build work will happen by me for 4 weeks or so.

Will try to check the forum at least twice a day.

Wish the other EMDrive replicators and experimenters all the best results in working out how to get us off this rock, using other thrust generation methods than long, controlled & directed explosions.
Please get well soon. Really miss our chats!!!
Shell

Online Rodal

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Also Iulian Berca had to leave his equipment behind while he goes to another country. 

Quote
Unfortunately i can not continue tests for the moment because i moved from original location (another country) and i left the frustum, magnetrons, transformer, there. I was not able to carry all my stuff.

I will continue tests, but i do not know when. :(
http://www.masinaelectrica.com/emdrive-independent-test/


It is obviously a conspiracy, like in the X files.
« Last Edit: 06/11/2015 11:50 PM by Rodal »

Offline SeeShells

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Also Iulian Berca had to leave his equipment behind while he goes to another country. 

Quote
Unfortunately i can not continue tests for the moment because i moved from original location (another country) and i left the frustum, magnetrons, transformer, there. I was not able to carry all my stuff.

I will continue tests, but i do not know when. :(
http://www.masinaelectrica.com/emdrive-independent-test/


It is obviously a conspiracy, like in the X files.
That's weird. I should almost feel afraid.

Offline rfmwguy

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@rfmwguy: If it's that esoteric, then perhaps a frustum is not an optimal shape. Perhaps the sidewalls need to follow some esoteric functional profile, as perhaps also do the end plates. But there's no way to get a handle on that sort of speculation without some hard mathematics behind your idea.

You are 100% correct. Trouble is, I cannot find sources that quantify entropy. Its certainly post-newtonian physics, which was solely focused on the 5% of "regular" matter and energy. I also agree that a Frustum may be happenstance, but an "opaque effect" may be focused there. The reason I say opaque is that if it was "solid" the Frustum would literally blow apart.  :o

Its similar to gravity. We have yet to determine how to make something "opaque" to it, something it affects less than normal matter.

Online Rodal

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...

Hence, why I said the frustum needs to be longer, so we can have something "closer" to Zeng & Fan's waveguide for traveling waves. If we are confined to 0-length past the cut-off diameter, attenuation is minimized, reflection and Q are higher. If we extend it out a full wavelength, we may attenuate 66% of the energy. The other 33% will be reflected with a larger phase shift than what Shawyer's design allows.

Also, the standing waves in a damped cavity will also frequency shift due to the damping. That's what gives Shawyer's design "some" thrust, but as I said, it is the rate of attenuation that will exert a higher force. So a longer front end to give the waves some traveling room to be attenuated faster, is what I believe is needed.

In other words, "design" the thruster more like Zeng and Fan and less like Shawyer.
Todd

Prof. Yang's EM Drive is significantly longer than Shawyer's

Description Mode Shape  Length (m)   Db (m) Ds (m)   Frequency (GHz)  Q  Force / PowerInput (mN/kW)
Shawyer Demo  TE012    0.187           0.28    0.14921    2.45             45000   80-243
Yang                  TE012    0.24            0.201  0.1492       2.45               1531   1070

Both have the same frequency, same mode shape, same Small Diameter

Yang achieves 10 to 5 times greater force/input power by operating with 29 times lower Q with a 28% longer EM Drive and 39% smaller big diameter.  All the opposite of what Shawyer recommends.

The wavelength is 299700000 m/s /(2.45*10^9 1/s) = 0.122 m

So Yang's EM Drive (which has the same small diameter as Shawyer's Demo) has a length (0.24 - 0.187) = 0.053 m

Yang's EM Drive is therefore about 1/2 wavelength longer than Shawyer's EM Drive truncated cone length
« Last Edit: 06/12/2015 01:02 AM by Rodal »

Offline ZuluMoon99

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Gentle Suggestion to those with the knowledge & skills to do this.

It would it not be possible to do both via the "Baby" route as done elsewhere, but with the dimensions changed to match both types of device?

Not sure of the costings of such an endeavour however.


Online Rodal

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...

Hence, why I said the frustum needs to be longer, so we can have something "closer" to Zeng & Fan's waveguide for traveling waves. If we are confined to 0-length past the cut-off diameter, attenuation is minimized, reflection and Q are higher. If we extend it out a full wavelength, we may attenuate 66% of the energy. The other 33% will be reflected with a larger phase shift than what Shawyer's design allows.

Also, the standing waves in a damped cavity will also frequency shift due to the damping. That's what gives Shawyer's design "some" thrust, but as I said, it is the rate of attenuation that will exert a higher force. So a longer front end to give the waves some traveling room to be attenuated faster, is what I believe is needed.

In other words, "design" the thruster more like Zeng and Fan and less like Shawyer.
Todd

Prof. Yang's EM Drive is significantly longer than Shawyer's

Description Mode Shape  Length (m)   Db (m) Ds (m)   Frequency (GHz)  Q  Force / PowerInput (mN/kW)
Shawyer Demo  TE012    0.187           0.28    0.14921    2.45             45000   80-243
Yang                  TE012    0.24            0.201  0.1492       2.45               1531   1070

Both have the same frequency, same mode shape, same Small Diameter

Yang achieves 10 to 5 times greater force/input power by operating with 29 times lower Q with a 28% longer EM Drive and 39% smaller big diameter.  All the opposite of what Shawyer recommends.

The wavelength is 299700000 m/s /(2.45*10^9 1/s) = 0.122 m

So Yang's EM Drive (which has the same small diameter as Shawyer's Demo) has a length (0.24 - 0.187) = 0.053 m

Yang's EM Drive is therefore about 1/2 wavelength longer than Shawyer's EM Drive truncated cone length


The most important parameter to Zeng & Fan is the cone half-angle.  It is drastically different between them:

Shawyer   (180/Pi) ArcTan[(0.28 - 0.14921)/(2*0.187)] = 19.275 degrees

Yang        (180/Pi) ArcTan[(0.201 - 0.1492)/(2*0.24)] =    6.159 degrees

Shawyer's EM Drive has a cone half-angle more than 3 times greater.

Yang's EM Drive is closer to a cylinder, which according to Zeng & Fan results in much greater attenuation.
« Last Edit: 06/12/2015 01:26 AM by Rodal »

Offline ThinkerX

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At this point I am wondering if there is enough publically available or deducible data  for one of the DIY types here to build a copycat version of Yeng and Fan's EM Drive device.

Also...would 'scaling down' the Yeng/Fan design to 'baby EM Drive' dimensions be feasible?  Seems to me a compact Yeng/Fan design producing anywhere near the amount of thrust as the original would put the EM Drive that much closer to cube sat testing. 

Offline rq3

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@rfmwguy: If it's that esoteric, then perhaps a frustum is not an optimal shape. Perhaps the sidewalls need to follow some esoteric functional profile, as perhaps also do the end plates. But there's no way to get a handle on that sort of speculation without some hard mathematics behind your idea.

Exactly. The frustum should be a 3D printed superconductor (for max Q, min bandwidth) in a fractal form so that the small end has zero real dimension, and infinite surface area. This would have the added benefit of snuffing cutoff evanescent modes, while enhancing 1/2 wave resonance.

Rip

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