Author Topic: EM Drive Developments - related to space flight applications - Thread 2  (Read 2104506 times)

Offline Rodal

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....

FYI: Marco's 1st draft paper went out on an email today from Paul M. and was distributed to about 35 individuals, including myself to my surprise. A swath of replies went back and forth, including a copy and paste of one of our posts here, between Dr. Rodal and myself. The comments were not constructive, as both Jack S. and Eric D. discarded the notion of gravity in the frustum, because GR would require overcoming the G/c^4 factor.

What these Dr's are missing is that we are not effecting the full spectrum from long wavelength RF to high energy quarks with what is happening in the frustum. It is only mimicking what gravity does in a very narrow bandwidth of the EM spectrum. The factor G/c^4 is only applicable for gravity that affects the FULL bandwidth of all energy and particles. G/c^4 comes from the integral over all modes in the field. We are not affecting all modes, just a few in a relatively low energy regime.

That's IMO of course.

Todd

I don't know who Jack S. and Eric D. are. If the letter is in reference to forum posts, I'm glad I had posted this some time ago:

http://forum.nasaspaceflight.com/index.php?topic=36313.msg1371241#msg1371241

Quote from: Rodal
this is a reference to NASA's experiments with an interferometer, where the laser beam goes through small portholes on a pillbox shaped cylindrical  EM Drive cavity.   

It is my understanding that NASA has not measured any thrust forces from this experiment involving a pillbox shaped EM Drive cavity.

NASA expected no significant thrust either, because the pillbox-shaped cavity is entirely symmetric in the longitudinal direction (parallel to the laser beam) and because the cavity did not contain any polymer dielectric insert in the experiments (as so far performed).

So if Jack S. and Eric D.  (whoever they are) are discussing "the notion of gravity in the frustum" I already pointed out that the Interferometer tests were not conducted with a frustum but instead with a pillbox shaped cylindrical geometry. As to the size of the spacetime distortion everybody is in agreement that one expects it to be extremely small.  That's the relevance of Marco Frasca's papers: and why Frasca's papers are so interesting, regarding the appropriate coupling.

QUESTION: In any case what are these people (Jack S. and Eric D. ) so excited about that they are writing about it?  What's the harm with Dr. White trying to find out?

As Frasca wrote in his webpage:

Quote
I would like to remember that White is not using exotic matter at all. Rather, he is working with strong RF fields to try to develop a warp bubble. This was stated here even if implicitly. Finally, an EmDrive device has been properly described here. Using strong external fields to modify locally a space-time has been described here.

If this will be confirmed in the next few months, it will represent a major breakthrough in experimental general relativity since Eddington  confirmed the bending of light near the sun. Applications would follow if this idea will appear scalable but it will be a shocking result anyway. We look forward to hear from White very soon.

Marco Frasca (2005). Strong coupling expansion for general relativity Int.J.Mod.Phys.D15:1373-1386,2006 arXiv: hep-th/0508246v3
« Last Edit: 05/08/2015 05:07 PM by Rodal »

Online WarpTech

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What if the photon rocket utilized the same construction with a cavity that would make the light move slower?

http://news.harvard.edu/gazette/1999/02.18/light.html

As it is possible to slow the light, then the lower its speed the bigger its thrust.
That's one thing. The other is that the thrust is multiplied by the number of bounccs.
That applies to MW waves in the resonating cavity. Hence - the bigger the number of bounces, the bigger the thrust.
You can actually amplify the photon rocket thrust as well.

I think a longer frustum will work better than multiple bounces, because the frustum should not be used to resonate, it should be used to attenuate and minimize heating. You can't derive more momentum from multiple bounces, than can be acquired by 100% attenuation of the wave after 1 bounce. The key is to minimize it's momentum at the first bounce by maximizing the wave's velocity at the far end.

Todd

Offline frobnicat

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...
In my opinion the engine resembles a very stiff speaker calculated for resonance frequency of 2,45MHz. The stiffer the material the better it resonates in this frequency. It's not only the Q that matters. That may be the reason the Cannae engine has lower efficiency - it is made of thinner metal that is less stiff.
...


The problem is that I can hear music from an open speaker (a "waveguide") but I cannot hear anything out of a speaker that is a closed cavity, such that all internal surfaces are perfectly reflective (the closed cavity of the EM Drive).

And if you open the big base of the EM Drive cavity, so that it becomes a speaker, then it is a very inefficient photon rocket, and therefore the claims of Shawyer don't make sense because they are thousands of time greater thrust per input power than a photon rocket  :'(


All right. Than maybe the magnetic field of the microwaves resonating inside the cavity "pushes" against the magnetic field of Earth. Anyway, the reversed parabolic (speaker-like) shape may send more waves to the wide end.

Whatever the reason it moves, all I am saying is that it has to be tested. Not only for different Q, but also different shapes, different MW injection positions and different stiffness of the 'emiting' structure.

Enough stiffness is important for the stability of cavity shape against deformations that might occur in a fraction of second, but there is no way a macroscopic "bell" can have acoustic modes (of significant amplitude) at 1GHz and above ! The time constants (between microwaves and possible acoustic modes) are many orders of magnitude apart.

Offline StrongGR

....

FYI: Marco's 1st draft paper went out on an email today from Paul M. and was distributed to about 35 individuals, including myself to my surprise. A swath of replies went back and forth, including a copy and paste of one of our posts here, between Dr. Rodal and myself. The comments were not constructive, as both Jack S. and Eric D. discarded the notion of gravity in the frustum, because GR would require overcoming the G/c^4 factor.

What these Dr's are missing is that we are not effecting the full spectrum from long wavelength RF to high energy quarks with what is happening in the frustum. It is only mimicking what gravity does in a very narrow bandwidth of the EM spectrum. The factor G/c^4 is only applicable for gravity that affects the FULL bandwidth of all energy and particles. G/c^4 comes from the integral over all modes in the field. We are not affecting all modes, just a few in a relatively low energy regime.

That's IMO of course.

Todd

I don't know who Jack S. and Eric D. are. If the letter is in reference to forum posts, I'm glad I had posted this some time ago:

http://forum.nasaspaceflight.com/index.php?topic=36313.msg1371241#msg1371241

Quote from: Rodal
this is a reference to NASA's experiments with an interferometer, where the laser beam goes through small portholes on a pillbox shaped cylindrical  EM Drive cavity.   

It is my understanding that NASA has not measured any thrust forces from this experiment involving a pillbox shaped EM Drive cavity.

NASA expected no significant thrust either, because the pillbox-shaped cavity is entirely symmetric in the longitudinal direction (parallel to the laser beam) and because the cavity did not contain any polymer dielectric insert in the experiments (as so far performed).

So if Jack S. and Eric D.  (whoever they are) are discussing "the notion of gravity in the frustum" I already pointed out that the Interferometer tests were not conducted with a frustum but instead with a pillbox shaped cylindrical geometry. As to the size of the spacetime distortion everybody is in agreement that one expects it to be extremely small.  That's the relevance of Marco Frasca's papers: and why Frasca's papers are so interesting, regarding the appropriate coupling.

QUESTION: In any case what are these people (Jack S. and Eric D. ) so excited about that they are writing about it?  What's the harm with Dr. White trying to find out?

As Frasca wrote in his webpage:

Quote
I would like to remember that White is not using exotic matter at all. Rather, he is working with strong RF fields to try to develop a warp bubble. This was stated here even if implicitly. Finally, an EmDrive device has been properly described here. Using strong external fields to modify locally a space-time has been described here.

If this will be confirmed in the next few months, it will represent a major breakthrough in experimental general relativity since Eddington  confirmed the bending of light near the sun. Applications would follow if this idea will appear scalable but it will be a shocking result anyway. We look forward to hear from White very soon.

Marco Frasca (2005). Strong coupling expansion for general relativity Int.J.Mod.Phys.D15:1373-1386,2006 arXiv: hep-th/0508246v3

Jose,

That is exactly the point about interference experiments. It was gravity that provides an explanation for White's interference experiments. For the frustum, I am working on it and the difficulty is to explain the net force that some people claims to have measured. With an interplay between electromagnetic field, cavity and space-time one should account for this but momentum conservation precludes it. Indeed, if exotic matter would be involved we would be done as, in this case, there is a violation of energy conditions in general relativity and nobody would complain. This is the root of the rejection of the work of EM Drive by the scientific community and there does not seem to be any mechanism inside such a cavity to provide exotic matter to put it at work. The other possibility is that general relativity should be corrected in some way by something else. So far I am sceptical about this because experiments supporting it are overwhelming while nothing is seen on the contrary. On the other side, White's measurement proves unequivocally that the space-time effect is there for a cavity.

Offline frobnicat

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And if you open the big base of the EM Drive cavity, so that it becomes a speaker, then it is a very inefficient photon rocket, and therefore the claims of Shawyer don't make sense because they are thousands of time greater thrust per input power than a photon rocket  :'(

I need to study @notsosureofit's GR calculation, but I think the point that is being missed here is, the resonant cavity acts as an EM Momentum amplifier. The Q factor comes in not "Just" as the number of photons stored, but also;  In GR as in PV, as the energy density inside the cavity increases, the wave velocity decreases. As velocity decreases, momentum increases. That "effective mass" of the photons in the cavity kicks in stronger.

p ~ E/v  and in the cavity v << c

This makes it a not-so "inefficient" photon rocket!

In the EM Drive design I proposed, we want the Q in the resonant cavity to be very high, but we do not want a high Q in the frustum. We want the backward-moving waves to expand, and the reflected waves moving forward to be attenuated. So we want a low Q, high attenuation in the frustum.

Todd

Sorry if this was already stated but, what is quantitatively the energy density inside the cavity (with a given Q of say, 10000) ? And how much quantitatively the wave velocity would decrease due to this energy density ? According to strict and uncontroversial interpretation of GR ?

Offline frobnicat

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And if you open the big base of the EM Drive cavity, so that it becomes a speaker, then it is a very inefficient photon rocket, and therefore the claims of Shawyer don't make sense because they are thousands of time greater thrust per input power than a photon rocket  :'(

I need to study @notsosureofit's GR calculation, but I think the point that is being missed here is, the resonant cavity acts as an EM Momentum amplifier. The Q factor comes in not "Just" as the number of photons stored, but also;  In GR as in PV, as the energy density inside the cavity increases, the wave velocity decreases. As velocity decreases, momentum increases. That "effective mass" of the photons in the cavity kicks in stronger.

p ~ E/v  and in the cavity v << c

This makes it a not-so "inefficient" photon rocket!

What if the photon rocket utilized the same construction with a cavity that would make the light move slower?

http://news.harvard.edu/gazette/1999/02.18/light.html

As it is possible to slow the light, then the lower its speed the bigger its thrust.
That's one thing. The other is that the thrust is multiplied by the number of bounccs.
That applies to MW waves in the resonating cavity. Hence - the bigger the number of bounces, the bigger the thrust.
You can actually amplify the photon rocket thrust as well.
See here:

Source: Wiki, http://upload.wikimedia.org/wikipedia/commons/8/8e/Photon-Thrust-Amplification.jpg

Note that it is not any more useful than a spring pushing between two points : this is just a way to beam action(force)/reaction(opposite force). In principle this could be used to build a "pillar of light" between ground and a craft rising to orbit (albeit the engineering seems too hard).

Quote
Bend this light path with optical fiber and you receive a powerful thruster.
Like this:




A very simple idea... nobody ever checked it yet, I suppose. I think this setup may be worth checking.
Please consider the fact that it is not c in the nominator, but the actual speed of light in the optical fiber. The slower the speed of the light in this apparatus, the greater the thrust!
The EmDrive works based on similar principle.

I'm sorry but to "bend" the light 180° around like that is equivalent in terms of momentum exchange to just bouncing it : in your above drawing the fibre bundle would receive 2F to the right from this momentum exchange. The total force on an isolated rigid craft would still be 0, as in the first drawing.

Offline Notsosureofit

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....

You are too fast for my old fingers...

Ultimately, what needs to be shown here is that the "covariant force vector equal to zero" on a photon in the accelerated frame is the same vector in the cavity rest frame (ie. can be transformed to) such that the force on a photon in the rest frame is a result of the (velocity) dispersion due to the shape of the cavity boundary conditions.  That transformation would show that the effect is to be expected under General Relativity.

The Q only enters in the case of a gravitational interaction through its role in calculating the number of photons (Total mass/energy) in the cavity.  If it was a Newtonian momentum interaction only the Power enters.  (I get zero when I try Newtonian for the reasons you have mentioned)

Note: I should probably use "Classical" instead of "Newtonian" but I think you would get the idea that we are looking at the 4-volume as an invariant rather than an integration over the surface of the boundary conditions of classical momentum exchange. That can apply as the summation of the (false gravitational?, ie. frame-dependent) forces on the individual photons to give the resultant force on the cavity.

I very much appreciate the explanation, unfortunately, I may not be able to understand this until I see the explicit mathematical formula for the 4-volume invariant, particularly the derivation of that invariant  :)

Unfortunately, I cannot do it intuitively as you can.

That would, of course, constitute a proof.

Well, OK, the obvious place to start is w/ the Einstein field equation G^jk = 8pT^jk.

  In the accelerated frame of reference w/ the acceleration, g = (c^2/(2*L*f^2))*(c/(2*Pi))

^2*X^2*((1/Rs^2)-(1/Rb^2)) [for this waveguide-like approximation].  We can set the stress–

energy tensor T^jk to a plane wave solution since the assumption here is that the acceleration

is such as to balance out the dispersion found in the rest frame.

     The internet pulls up the Wikipedia entry:

 https://en.wikipedia.org/wiki/Monochromatic_electromagnetic_plane_wave

 [which has already been referenced by @StrongGR] and

 http://en.wikipedia.org/wiki/Talk%3AMonochromatic_electromagnetic_plane_wave

 which is new [?] by Chris Hillman, which points to;

 http://en.wikipedia.org/wiki/Pp-wave_spacetime.

Edit: I used to have
 Penrose, Roger (1965). "A remarkable property of plane waves in general relativity". Rev. Mod. Phys. 37: 215–220. Bibcode:1965RvMP...37..215P. doi:10.1103/RevModPhys.37.215
around here somewhere, I'll look.

« Last Edit: 05/08/2015 06:35 PM by Notsosureofit »

Online WarpTech

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....
And if you open the big base of the EM Drive cavity, so that it becomes a speaker, then it is a very inefficient photon rocket, and therefore the claims of Shawyer don't make sense because they are thousands of time greater thrust per input power than a photon rocket  :'(

I need to study @notsosureofit's GR calculation, but I think the point that is being missed here is, the resonant cavity acts as an EM Momentum amplifier. The Q factor comes in not "Just" as the number of photons stored, but also;  In GR as in PV, as the energy density inside the cavity increases, the wave velocity decreases. As velocity decreases, momentum increases. That "effective mass" of the photons in the cavity kicks in stronger.

p ~ E/v  and in the cavity v << c

This makes it a not-so "inefficient" photon rocket!

In the EM Drive design I proposed, we want the Q in the resonant cavity to be very high, but we do not want a high Q in the frustum. We want the backward-moving waves to expand, and the reflected waves moving forward to be attenuated. So we want a low Q, high attenuation in the frustum.

Todd

Sorry if this was already stated but, what is quantitatively the energy density inside the cavity (with a given Q of say, 10000) ? And how much quantitatively the wave velocity would decrease due to this energy density ? According to strict and uncontroversial interpretation of GR ?

My questions as well. Working on it... Like I said, I have a day job and not enough hours in a day. Even if there were no amplification from GR effects, it still amplifies the momentum simply due to the constraints of the cavity forcing a reduced wave velocity.

Todd


Offline TheTraveller

....

Did you or anyone else ever write an excel spreadsheet to calc Shawyers Design Factor? If so pls link it or if not please consider doing it as your skills there are much better than mine.
Yes I have calculated it, but it is a Mathematica program, not an Excel spreadsheet.  I posted (earlier in the thread) comparisons of the measurements vs. predictions using Shawyer's and McCulloch's formulas.

You may want to PM @aero to ask whether he did it with Excel (if my memory is correct @aero also calculated Shawyer's Design Factor, as I recall having exchanges in this forum with him).

And of course, when running your program, you will first check your results vs. Shawyer's published Design Factor results, etc., to make sure that your program is correct.
Mathematica looks interesting but maybe later as I suspect there would be a learning curve.

Is this still your Design Factor equation?

Thanks for your assistance. Most appreciated.




I recognize that equation is my Mathematica-writing, but I need a link to the message where I posted it, in order to remember the context.  Too long ago  :)
Apologies for the delay. Requested link here:
http://forum.nasaspaceflight.com/index.php?topic=29276.msg1276053#msg1276053

Aero did reply but his Design Factor equation did not include Rf

Quote
I did, but the Excel file is not suitable for distribution, having all of my work scattered throughout a 500 line file with little or no embedded explanations. That is, it's un-usable even for me, without considerable time discovering what I intended to do. For example, here is my design factor, Df, equations. I think the variables are:
Lo - length
Lg1-diameter
Lg2-diameter
Df = 0.844   Df=S_o*Lo((1/Lg1) - (1/lg2))  where S_o = (1-(Lo^2/(Lg1*Lg2)))^-1         
Combining   Df = Lo*( 1 - (Lo^2/(Lg1*Lg2)))^-1 *((1/Lg1)-(1/Lg2))     

So before turning either your or Aero's equation to Excel and posting it to the Wiki for all replicators to use, wpuld you please give some feedback on which is correct?

From my trying to follow the Shawyer DF equations, it seems your equation which uses Rf imay be correct?

Would appreciate a set of data variables that I can use to verify my excel equation gives the same results as your Mathematica equation.

As always, thanks for the assistance.
Appreciated.
« Last Edit: 05/08/2015 07:18 PM by TheTraveller »
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Offline Blaine

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Sorry if this has nothing to due with anything, but just a random thought popped into my head.

http://www.usna.edu/Users/oceano/raylee/RainbowBridge/RB_images/Fig8_7.jpg

To see how this works, we first note that supernumerary bows are not caused by interference between two light waves. Instead, two different portions of the same light wave interfere. In Fig. 8-7, we once again show a circular slice through a raindrop, much as we did in Fig. 6-5. Now, rather than parallel light rays entering the drop, a series of wave ridges and troughs (Fig. 8-7’s vertical lines) advances toward the drop as a front of parallel waves. Think of the parallel lines as representing the wave fronts of parallel rays of sunlight. Rays, which are always locally perpendicular to their corresponding waves, show the waves’ direction of travel.

Feel free to delete if this is stupid or misleading.  Again, its just a random thought whilst thinking about waves in relation to each other.
Weird Science!

Online aero

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Well, since we're on random thoughts, I had one, too.

As I have posted on several occasions, there exist a number of papers reporting experiments which seem to show  evanescent wave superluminal velocity and evanescent wave superluminal momentum. That idea is not well accepted in the general physics community yet the experiments do show something out of the ordinary. Does anyone suppose that the experimental results that are explained by superluminal velocity/momentum could be also, perhaps better, explained by Dr. White's quantum vacuum concepts?

And regarding Shawyer's design factor, I did program Dr. Rodel's equation and did match his numbers but it was some time ago and is now lost in the fog of the past.
Retired, working interesting problems

Offline Notsosureofit

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Edit: I used to have
 Penrose, Roger (1965). "A remarkable property of plane waves in general relativity". Rev. Mod. Phys. 37: 215–220. Bibcode:1965RvMP...37..215P. doi:10.1103/RevModPhys.37.215
around here somewhere, I'll look.

Amazing !  Found it after all these years.  I have to re-read and re-understand it of course, but check Fig. 1. "The sandwich wave" where you have a section of curved space-time sandwiched between flat.  That alone is closer to this situation than anything I've seen so far.

The previous article, Rosen, Joe. "Embedding of Various Relativistic Riemannian Spaces in Pseudo-Euclidean Spaces" contains tables of transforms.  That could prove invaluable !
 
« Last Edit: 05/08/2015 08:08 PM by Notsosureofit »

Offline TheTraveller

And regarding Shawyer's design factor, I did program Dr. Rodel's equation and did match his numbers but it was some time ago and is now lost in the fog of the past.
Is ok. Will recreate the Design Factor excel spreadsheet and post to the WiKi for all to use. Will never be lost again.

I trust Dr. Rodal will provide a few data sets so I can verify the results? PLEASE.
« Last Edit: 05/08/2015 08:16 PM by TheTraveller »
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Offline rfmwguy

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Its great to see continuing discussions on this emdrive forum. There are Theorists and there are Observers. I tend to fall into the latter category and appreciate all those willing to build their own test articles, sharing plans & results. Onwards and upwards...

Offline Rodal

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Edit: I used to have
 Penrose, Roger (1965). "A remarkable property of plane waves in general relativity". Rev. Mod. Phys. 37: 215–220. Bibcode:1965RvMP...37..215P. doi:10.1103/RevModPhys.37.215
around here somewhere, I'll look.

Amazing !  Found it after all these years.  I have to re-read and re-understand it of course, but check Fig. 1. "The sandwich wave" where you have a section of curved space-time sandwiched between flat.  That alone is closer to this situation than anything I've seen so far.

The previous article, Rosen, Joe. "Embedding of Various Relativistic Riemannian Spaces in Pseudo-Euclidean Spaces" contains tables of transforms.  That could prove invaluable !

An earlier paper, this time by Bondi, on sandwich waves and plane gravitational waves, that, unlike the other ones, has a PDF with a link   :):

http://www.itp.kit.edu/~schreck/general_relativity_seminar/Gravitational_waves_in_general_relativity_exact_plane_waves.pdf

Gravitational waves in general relativity
III. Exact plane waves
BY H. BONDI* AND F. A. E. PIRANIt
King's College, London
AND T. ROBINSON
Lately of University College of Wales, Aberystwyth
(Communicated by W H. McCrea, F.R.S.-Received 18 October 1958)


Plane gravitational waves are here defined to be non-flat solutions of Einstein's empty spacetime
field equations which admit as much symmetry as do plane electromagnetic waves,
namely, a 5-parameter group of motions. A general plane-wave metric is written down and
the properties of plane wave space-times are studied in detail. In particular, their characterization
as 'plane' is justified further by the construction of 'sandwich waves' bounded on both
sides by (null) hyperplanes in flat space-time. It is shown that the passing of a sandwich wave
produces a relative acceleration in free test particles, and inferred from this that such waves
transport energy.
« Last Edit: 05/08/2015 08:17 PM by Rodal »

Offline Econocritic

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Consider the following EM Drive design:

1st component: A symmetrical resonator cavity that is optimized to store energy at high Q, and plays no role in thrust. Here, we want to store the lowest order mode that the waveguide can sustain because it has the slowest wave velocity inside the waveguide. By targeting the slowest wave velocity, we are maximizing the amount of stored electromagnetic momentum for a given amount electromagnetic energy.

p = E/v, where  v << c inside the waveguide.
E = P*t, energy is power in x time (assuming a lossless cavity)

2nd component: We need a frustum that matches the diameter of the resonant chamber "at the small end" and slowly expands to a TBD length and diameter. As the waveguide expands, the wavelength will be increasing proportional to the increasing wave velocity. We want it to expand to near it's free space value.

...

Is this design analogous to the "Modified Aluminum Cavity for TE011 Mode Resonance" previously presented by Paul March?  Note, there appears to be two chambers separated by a 1/16" plate (aluminum?).  As an avid follower of this thread I have not noticed any comments about the Eagleworks dual chamber design.  However, I could be misinterpreting the attached image. 

This has been a truly fascinating discussion which has never ceased capturing my attention. I feel fortunate to passively witness.  Thank you all, especially the replicators.

-Matthew Trimble       
« Last Edit: 05/09/2015 07:04 AM by Econocritic »

Offline TheTraveller

Its great to see continuing discussions on this emdrive forum. There are Theorists and there are Observers. I tend to fall into the latter category and appreciate all those willing to build their own test articles, sharing plans & results. Onwards and upwards...
There are also Replicators / Builders here ;)
« Last Edit: 05/08/2015 08:19 PM by TheTraveller »
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Offline Rodal

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Consider the following EM Drive design:

1st component: A symmetrical resonator cavity that is optimized to store energy at high Q, and plays no role in thrust. Here, we want to store the lowest order mode that the waveguide can sustain because it has the slowest wave velocity inside the waveguide. By targeting the slowest wave velocity, we are maximizing the amount of stored electromagnetic momentum for a given amount electromagnetic energy.

p = E/v, where  v << c inside the waveguide.
E = P*t, energy is power in x time (assuming a lossless cavity)

2nd component: We need a frustum that matches the diameter of the resonant chamber "at the small end" and slowly expands to a TBD length and diameter. As the waveguide expands, the wavelength will be increasing proportional to the increasing wave velocity. We want it to expand to near it's free space value.

...

Is this design analogous to the "Modified Aluminum Cavity for TE011 Mode Resonance" previously presented by Paul March?  Note, there appears to be two chambers separated by a 1/16" plate (aluminum?).  As an avid follower of this thread I have not noticed any comments about this dual chamber design.  However, I could be misinterpreting the attached image. 

This has been a truly fascinating discussion which has never ceased capturing my attention. I feel fortunate to passively witness.  Thank you all, especially the replicators.

-Matthew Trimble       

Thank you for pointing out that important fact, that had escaped my attention.  Much appreciated  :)

Offline TheTraveller

Consider the following EM Drive design:

1st component: A symmetrical resonator cavity that is optimized to store energy at high Q, and plays no role in thrust. Here, we want to store the lowest order mode that the waveguide can sustain because it has the slowest wave velocity inside the waveguide. By targeting the slowest wave velocity, we are maximizing the amount of stored electromagnetic momentum for a given amount electromagnetic energy.

p = E/v, where  v << c inside the waveguide.
E = P*t, energy is power in x time (assuming a lossless cavity)

2nd component: We need a frustum that matches the diameter of the resonant chamber "at the small end" and slowly expands to a TBD length and diameter. As the waveguide expands, the wavelength will be increasing proportional to the increasing wave velocity. We want it to expand to near it's free space value.

...

Is this design analogous to the "Modified Aluminum Cavity for TE011 Mode Resonance" previously presented by Paul March?  Note, there appears to be two chambers separated by a 1/16" aluminum plate.  As an avid follower of this thread I have not noticed any comments about this dual chamber design.  However, I could be misinterpreting the attached image. 

This has been a truly fascinating discussion which has never ceased capturing my attention. I feel fortunate to passively witness.  Thank you all, especially the replicators.

-Matthew Trimble       
According to Paul March, this is the cavity EW will be using to do a more formal replication of Shawyer and the Chinese using Shawyers Teeter Totter balance beam, which I assume means operation in a vertical orientation.

Trust EW will remove the partition in their alum cavity?
« Last Edit: 05/08/2015 08:29 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 maciejzi

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Bend this light path with optical fiber and you receive a powerful thruster.
Like this:




A very simple idea... nobody ever checked it yet, I suppose. I think this setup may be worth checking.
Please consider the fact that it is not c in the nominator, but the actual speed of light in the optical fiber. The slower the speed of the light in this apparatus, the greater the thrust!
The EmDrive works based on similar principle.

I'm sorry but to "bend" the light 180° around like that is equivalent in terms of momentum exchange to just bouncing it : in your above drawing the fibre bundle would receive 2F to the right from this momentum exchange. The total force on an isolated rigid craft would still be 0, as in the first drawing.

Photons are in a different frame of reference. The above system should move to the left.

The above system as well as EmDrive is like a cavity with an externally attached pendulum. The pendulum's ball (represents light wave or microwave) bounces in it. And moves the light/MW cavity to the side where it bounces the most.

« Last Edit: 05/08/2015 08:48 PM by maciejzi »

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