Author Topic: EM Drive Developments - related to space flight applications - Thread 3  (Read 1801271 times)

Offline hhexo

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Wouln't the acoustic propulsion (hat tip to Prof Uno Ingard at MIT) of a tapered bottle be a better acoustic analogue to the EM Drive than a string?

Hm... Not really, because we know the bottle is open-ended and there is air emission/influx in an asymmetric pattern (as I think somebody pointed out a number of posts ago).
The EmDrive is allegedly a closed cavity. Similarly, the wave in a string does not "escape".

Rocking jokes aside, I'm semi-serious with this.
If the effect is only due to standing waves in a variable refraction medium, it should exist with confined acoustic waves.
Of course, the EmDrive is a much more complex beast. But, if we prove that there is no effect with a string, then we can exclude the effect comes from just the standing waves and we can focus our effort elsewhere (e.g. evanescent waves).

Offline Rodal

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...

P.S.  A corollary thought is: if the material matters (it interacts) with respect to the flux escape, then should SeeShells' copper mesh EMDrive show increased performance in with respect to cone size and power input compared with a sheet copper EMDrive?
Not necessarily if the mesh opening is homogeneous throughout.  It may show increased peformance if:


a) no mesh opening or much smaller mesh opening on all surfaces except the small end

b) specially designed nozzle like openings at the small end in a whispering-gallery mode (which is known to enhance evanescent wave coupling) as shown in aero's movie:

http://forum.nasaspaceflight.com/index.php?action=dlattach;topic=37642.0;attach=1033772

(did aero know about whispering-gallery modes enhancement of evanescent wave coupling or did he independently  think of it ?)
« Last Edit: 06/26/2015 08:03 PM by Rodal »

Offline Rodal

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Wouln't the acoustic propulsion (hat tip to Prof Uno Ingard at MIT) of a tapered bottle be a better acoustic analogue to the EM Drive than a string?

Hm... Not really, because we know the bottle is open-ended and there is air emission/influx in an asymmetric pattern (as I think somebody pointed out a number of posts ago).
The EmDrive is allegedly a closed cavity. Similarly, the wave in a string does not "escape".

Rocking jokes aside, I'm semi-serious with this.
If the effect is only due to standing waves in a variable refraction medium, it should exist with confined acoustic waves.
Of course, the EmDrive is a much more complex beast. But, if we prove that there is no effect with a string, then we can exclude the effect comes from just the standing waves and we can focus our effort elsewhere (e.g. evanescent waves).
I was the one that originally pointed out that the EM Drive has end caps, unlike the bottles in the video.

But, .. look closer: take a gander at aero's movie http://forum.nasaspaceflight.com/index.php?action=dlattach;topic=37642.0;attach=1033772  and rfmwguy's comments.  There is a non-metallic sealant at the end, and a whispering-gallery mode can take place to enhance evanescent-wave coupling and hence exit of photons at superluminal group-velocities.  This is analogous to a supersonic jet exit from a nozzle.  Moreover the acoustic Helmholtz resonance is the exact acoustic analogue of the microwave cavity Helmholtz resonance (except for the fact that the number of gas molecules is constant while the number of photons is not constant, and the fact that the photon gas has different temperature dependence).

The guitar string is not as good an analogue of the the microwave cavity Helmholtz resonance.
« Last Edit: 06/26/2015 09:58 PM by Rodal »

Offline sghill

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Wouln't the acoustic propulsion (hat tip to Prof Uno Ingard at MIT) of a tapered bottle be a better acoustic analogue to the EM Drive than a string?



I don't see how.  Put a bottlecap on those bottles, and if they still work, then it could be called an analog.  Those bottles are spinning because the compression wave created by the speaker is forcing the bottles shape to change, and puff air out the openings in a preferential direction.

Bring the thunder Elon!

Offline SeeShells

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https://hal.archives-ouvertes.fr/jpa-00246781/document
On the other hand, the 60 mm length of this region corresponds to a delay time of 0.2 nsec of light in vacuum, this is clearly longer than the measured delay in the first 5 nsec duration of the pulse superluminal conditions are present both for the center of gravity and the maximum value of the electromagnetic packet. Furthermore this confirmes the correctness of the frequency domain data and the corresponding Fourier evaluation [2, 3]. The zerc-time traversal described in references [2] and [3] proves to be correct, I-e- there is no additional time delay caused by an additional length of the evanescent region.
<end quote>

I know group velocities can appear greater than the speed of light but because the wave form information was previously propagated at light speed.  I suspect that may be what is happening and maybe this is what this paper is also suggesting. 

https://scholar.google.com/scholar?cluster=3707515693059191286&hl=en&as_sdt=5,48&sciodt=0,48

It is an interesting question. 

hmm on a second maybe they are implying that group velocity can't explain the results? "Finally, we discussed a pos-sible interpretation of the results, favoring the argument that the group velocity cannot be interpreted as a tunneling ve-locity."  Fascinating.

I guess I am still skeptical that near field's can travel faster than light.  If that were so I don't know what would stop us from building a circular array and sending messages back in time.  That is actual signals that move faster than light would travel back in time like tachyons.
I used to be not just skeptical, but, Ahem, hostile, to this idea of superluminal transmission, because of violation of causality, and the appearance that a tachyonic telephone could be constructed.

However, upon examining the papers in detail, there is no doubt in my mind that it is impossible to send information using this superluminal transmission.  It has been shown a number of times, by different authors that this is impossible, just as it is impossible to use the coherence phenomenon of instantaneous action at a distance to send information.  This is precluded by quantum mechanics, in both cases.  There is nothing deterministic about the superluminal evanescent wave transmission that can be used to send any information superluminally, as what will be received superluminally will be scrambled up randomly in a non-deterministic way.  The signal received at the other end would be incomprehensible and contain no information.

Hence I no longer have any problem with this type of superluminal action.  Besides the impossibility to use it to send information, the superluminal aspect is restricted to the group velocity and not to the phase velocity, so one has to be careful about the physical interpretation of this superluminal effect.
Just read this and you're right no information can be transmitted FTL but I'm not ready to throw the baby out with the bath water because and quote " To summarize, we have found that a single evanescent electromagnetic wave offers a rich and highly non-trivial structure of the local momentum and spin distributions. In sharp contrast to standard photon properties, evanescent waves carry helicity-independent transverse spin and
helicity-dependent transverse momentum. Moreover, the transverse momentum turns out to be a fundamental spin momentum introduced by Belinfante in field theory and first remarked in optics (as an unusual Poynting vector) by Fedorov. We have examined the measurements of the extraordinary spin and momentum in the evanescent field by analysing its interaction with a probe particle. Analytical evaluations and exact numerical simulations based on parameters of typical optical-manipulation experiments show that the transverse helicity-independent spin (and also the vertical electric spin for diagonal polarizations) can be detected straightforwardly via the radiation torque exerted on an absorbing small particle. At the same time, the Belinfante–Fedorov’s spin momentum does not exert the standard optical pressure in the dipole approximation, which confirms its ‘virtual’ character (in contrast to Fedorov’s interpretation).
Nonetheless, it appears detectable (in contrast to the field-theory interpretation) via a helicity dependent transverse optical force from the higher-order non-weak interaction with Mie 11 particles. Thus, an exceptional evanescent-wave structure with pure spin transverse momentum offers a unique opportunity for the direct observation of this fundamental field-theory quantity, which was previously considered as ‘virtual’.
http://arxiv.org/ftp/arxiv/papers/1308/1308.0547.pdf

Shell

Offline Rodal

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Wouln't the acoustic propulsion (hat tip to Prof Uno Ingard at MIT) of a tapered bottle be a better acoustic analogue to the EM Drive than a string?



I don't see how.  Put a bottlecap on those bottles, and if they still work, then it could be called an analog.  Those bottles are spinning because the compression wave created by the speaker is forcing the bottles shape to change, and puff air out the openings in a preferential direction.

Answered here:  http://forum.nasaspaceflight.com/index.php?topic=37642.msg1394660#msg1394660

Offline Rodal

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...
Just read this and you're right no information can be transmitted FTL but I'm not ready to throw the baby out with the bath water ...

On the contrary, the fact that information cannnot be transmitted FTL is a plus for the theory and not a reason to feel like throwing babys out the windows :)

There is no need whatsoever for the evanescent waves to carry information anymore than there is a need for the isentropic supersonic exit from a rocket nozzle needing to carry information and convey messages out of the nozzle. All that is needed is to have enough momentum (not information) exit the spaceship in one direction asymmetrically, for the spaceship to accelerate.

https://www.grc.nasa.gov/www/k-12/airplane/isentrop.html

I like babies :)
« Last Edit: 06/26/2015 08:11 PM by Rodal »

Offline SeeShells

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The only way these things will work is to interact with an outside environment. I believe I've figured out that this mechanism is the finite conductivity of copper + heat, allowing voltage drop to form on the conductor, AKA "Ohm's Law". Where there is voltage and current there are volt-seconds, or magnetic flux that is passing through that open window. So heat and poor conductivity allow flux to escape (tunnel) through the copper.

So, with the increased wall thickness of the baby EMDrive with respect to the cone size and power input, should we expect no meaningfully significant thrust measurements, or is the copper "transparent" to the tunneling flux?

P.S.  A corollary thought is: if the material matters to the flux escape, then should SeaShells' copper mesh EMDrive show increased performance in with respect to cone size and power input?
Was out in my highly envied "shop" ;) today and haven't been able to follow post to post and I'll catch up to where I left off reading in a bit. You're right in thinking I feel that the copper has the magic squirrel sauce that makes it work and one reason I shelved the other two (for now) designs to push on the perforated copper design and testing.

One time I had access to a very sharp staff and we were contemplating on using "light Tweezers" to move very small gold wires on a semiconductor chip, it was a viable project, but because of things that were not related to "it's not a good idea" it had to be shelved.

The things that intrigued us was the ability of an evanescent wave to manipulate an object, a wave that couldn't carry information or couldn't do work with it, hmmmm, it seemed to do. It still does intrigue me and I believe it can be a clue of why this cavity works the way it does.
Nice clue, thanks Dr. Rodal!
http://arxiv.org/ftp/arxiv/papers/1308/1308.0547.pdf

I'm still digging into it and I know they are much smarter people here than me that have a more detailed knowledge in depth and breadth and right now I'm trying to be a one girl band and finding it hard.

Love for you all to beat this idea up and kick it around. I think the evanescent waves due to their extraordinary nature and spooky weird actions can impart a directional momentum and thrust to the EMdrive.

Back to reading a little and then into my playground.

Shell
So the question arises what could it be interacting with and I'm stuck here as it going to take some time to mix and match the two together. It's the QV and I think the two link bigtime.
http://calphysics.org/inertiamath.html

Just had a brick fall on my pointing vector finger big time in my play shop and it's a bugger to type with it throbbing and a big band aid.

Shell

Offline Rodal

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...Those bottles are spinning because the compression wave created by the speaker is forcing the bottles shape to change, and puff air out the openings in a preferential direction.
I would not word it that way.  There is air coming in and out in the same vector orientation, but in different directions because when coming out it is in the form of a jet, while when going in it is a suction effect that instead of being well directed it pulls air from all directions like the suction from a vacuum cleaner.

It is the difference in air flow between suction and jet-nozzle effect that is responsible for the propulsion.  In the EM Drive, there may be a similar effect, as shown by aero, at the circumferential gaps of the bases with the cone.

Both the acoustic and the electromagnetic resonance equation solutions were solved by Helmholtz and both still bear his name.  SAME EQUATION, the Helmholtz equation

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

Here is young Helmholtz looking at us, 150 years ago :)  :



Yes, it is not exactly the same as in the movie (although Todd is proposing that an even opening like in the movie may be better... he maybe right)

Right now, for the tiny forces of the EM Drive one maybe relying on evanescent wave leakage and a whispering-gallery mode forming around the exit circle, as shown by aero's movie.

And in an EM Drive there may be only photons coming out, and not coming in.  The magnetron feeds the photons inside it.
« Last Edit: 06/26/2015 08:30 PM by Rodal »

Offline SeeShells

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...
Just read this and you're right no information can be transmitted FTL but I'm not ready to throw the baby out with the bath water ...

On the contrary, the fact that information cannnot be transmitted FTL is a plus for the theory and not a reason to feel like throwing babys out the windows :)

There is no need whatsoever for the evanescent waves to carry information anymore than there is a need for the isentropic supersonic exit from a rocket nozzle needing to carry information and convey messages out of the nozzle. All that is needed is to have enough momentum (not information) exit the spaceship in one direction asymmetrically, for the spaceship to accelerate.

https://www.grc.nasa.gov/www/k-12/airplane/isentrop.html

I like babies :)
Yep, love all babies here.
Anyway, the reason I posted this a few pages ago was that it was leading up to work can be done with a evanescent wave, not so much it was spooky action although that may come into play further down the line when the QV is taken into consideration.

Offline WarpTech

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When I've checked, rechecked, and validated my equations, I'll let you know. :) I ran a spreadsheet last night to determine the required stored energy for a given force. The numbers seem reasonable given the available data, "IFF" there were no plate on the big end and the flux could get out. With the big end sealed, the force is there, but it's cancelled at the big end. It's not going to do anything unless the flux can get out.

One of the key issues I've tried to answer is, what is the drift velocity of an Xnm mode in a tapered cylinder cavity? In a straight cylindrical cavity, a resonant TExx mode at position "x" along the cylinder doesn't move down the pipe, it's velocity is zero and it's frequency doesn't shift due to it's position. In a cone it does.
Todd

Please elaborate as to why you think that the velocity of a resonant TEmn is not zero, that it moves down, and that the frequency shifts.  Are you talking about phase shift due to geometrical attenuation?  And what do you mean by the TEmn moving down?

In due time, I don't want to give away the farm just yet. 8) In a few days maybe, when I finish re-re-rewriting my paper, I'll let everyone in on the Tech. No secrets! I just don't want to totally embarrass myself (again) if I'm wrong. My DC solution works for a closed cavity, it's just easier to explain using an Xnm cylindrical harmonic mode and photons in an open ended cavity, rather than current density, flux density and heat in a closed cavity. It's also easier to explain using a TE mode than a TM mode.

magnetic flux = photons
Thanks for waiting...
Todd

Offline WarpTech

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I don't recall whether or not I've posted this video, so here it is. I was fooling around back in April trying to create evanescent waves when I came across this very unusual pattern. I don't know that evanescent waves are involved at all but something unusual is showing up. You tell me?

Superluminal velocity? Well, strange things do happen.
Yes, in the acoustic analogue, this would be tantamount to shock waves due to exit speeds faster than the speed of sound.  The shock waves would look like that.

Wow! That's cool and relevant. One of the issues I've been having is the phase velocity > c inside the cone, so what happens when it exists the big end? I think this video just showed me what happens.

Thank you.
Todd

Offline mittelhauser

I am not sure if the attached has been covered on here before but it states

"EmDrive Licence: 10 year exclusive master licence £100,000,000 comprised of
2 years development to Flight Qualified status @ £10m per year pro rata, plus
consultancy from Roger Shawyer to divest expertise.
Break clause at 2 years, if project fails to achieve FQ status all rights revert to SPR.
A further 3 year exclusive use of EmDrive @ £10m per annum.
After 3 years of exclusive use, master licensee is required to sub licence technology on
similar terms, if requested, to third parties.
For 10 years, royalties of £150k per space vehicle using EmDrive (equivalent to 10% of
the saving on build cost).
After 10 years, master licensee has first right of refusal on renewing master licence"


I know this possibly quite old but may be of interest.

Mike.

Source: http://ind-tech.com/wp-content/uploads/2014/11/Investment-Memorandum-final.pdf
This is an Investment Memorandum.  The quote comes from section six "Financial Information", and is preceded by, "The company believes that in the next 9 months it can negotiate an exclusive licence and royalty structured in the following way."

~Kirk

I've been an active lurker for months but this prospectus was finally too much.  I hate the side debates that take away from the interesting exploration of whether or not there might be a true phenomenon here but I worry that somebody inexperienced will read that document and thing it means something worthwhile.

FWIW, I look at a *lot* of startup investments on a daily/weekly basis.  If that document had passed my desk, it would have hit the trash can with enough force than nobody would have any difficulty measuring it.  :)  There are so many red flags to an investor I don't know if I can even delineate them all. 

Let's be clear, if you are asking for an investment in a company like this, you need to demonstrate some combination of:
A) Evidence that you have created something unique AND you have IP protection around it
B) Real customers, revenues and pipeline

We all know that the rubber meets the road with (A) and there is not even a hint of real evidence (e.g. "documentation will be provided to back up these claims once an NDA is in place").  Even worse there is no coverage of IP protection or anything which would lead to a valuation in the tens of millions IF the claims turned out to be true. 

In terms of B, OMFG.  Where do I start?  The statement "The company believes that in the next 9 months it can negotiate an exclusive licence ... for  £100,000,000".  LOL.  Uh huh.  I wouldn't think you could make a more outrageous claim than the drive itself without ANY supporting material but they succeeded. 

Do you have an LOI with anyone?  There are maybe 10 companies in the world that could do a deal like the one suggested.  They all have plenty of venture capital ties (either in house or out of house).  If any of them were "likely" to be doing a deal in the next 9 months for £100M, you certainly would not be putting out blind memorandums trying to raise a paltry £1.5M in £20k chunks.

Specific HUGE red flags if I was a prospective investor:
* "Three of the company’s existing minority shareholders are looking to divest some of their shares"  - right as you are about to "prove" it works and sign a £100M deal, you have folks looking to bail?  Uh huh. 
* Cash in hand is £100k but your burn is only £7k per month?!?  I'm all for start-ups being cash conservative but that's insane if you are on the edge of a £100M deal.
* The £250k investment was in 2005!  Um.  Show me WTF has happened with that investment money in 10 years.

God, I could go on and on but I'll stop just because I'm getting annoyed.

I truly hope that it turns out that there is something interesting happening with the EMDrive but from my (very experienced investment) seat, Sawyer is feeling a LOT like Andrea Rossi's e-CAT. 

Both technologies still *could* be proven interesting but their main proponents are doing a LOT more to hurt the credibility than help it.

Offline rfmwguy

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Wouln't the acoustic propulsion (hat tip to Prof Uno Ingard at MIT) of a tapered bottle be a better acoustic analogue to the EM Drive than a string?



I don't see how.  Put a bottlecap on those bottles, and if they still work, then it could be called an analog.  Those bottles are spinning because the compression wave created by the speaker is forcing the bottles shape to change, and puff air out the openings in a preferential direction.

Except sound moves through a medium which has mass and can flow. More importantly, the flowing of air can be blocked by plastic barriers.

If electromagnetic waves are moving through a medium capable of flowing, I don't imagine copper would necessarily impede the flow of that medium. If it did, we would put copper propellers onto our space ships and fly them like airplanes to other planets.

I think it is better to imagine the above video as if the bottle could change the propagation of sound waves without blocking the flow of air.[Edit] That is if we intend to try and use it as an analogue for the EM drive. Obviously the question then is: would it still move? How would you optimize it?
« Last Edit: 06/26/2015 09:06 PM by Allogonist »

Offline rfmwguy

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Wouln't the acoustic propulsion (hat tip to Prof Uno Ingard at MIT) of a tapered bottle be a better acoustic analogue to the EM Drive than a string?



I don't see how.  Put a bottlecap on those bottles, and if they still work, then it could be called an analog.  Those bottles are spinning because the compression wave created by the speaker is forcing the bottles shape to change, and puff air out the openings in a preferential direction.

Except sound moves through a medium which has mass and can flow. More importantly, the flowing of air can be blocked by plastic barriers.

If electromagnetic waves are moving through a medium capable of flowing, I don't imagine copper would necessarily impede the flow of that medium. If it did, we would put copper propellers onto our space ships and fly them like airplanes to other planets.

I think it is better to imagine the above video as if the bottle could change the propagation of sound waves without blocking the flow of air.
Perhaps what is being demonstrated here is despite just one inlet/outlet, thrust is provided without breaking any conventional laws of physics. If you think of space as an electromagnetic/partical soup, it is not empty nor unmodulate-able (otherwise EM waves could not radiate, as sound does in air perhaps). So the resonance/standing waves of an EM cavity with a single outlet should theoretically do the same in space, unless you think the vacuum of space is nil. Air molecules are massive, granted, but EM concentrations in a resonant cavity should far EXCEED their near-space ambient surroundings and should hit it with some force...theoretically, that is. It sounds like a photon rocket, but perhaps persistence or elasticity of microwave radiation differs from light photons...above my head at the present time...tilt.

Online aero

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@Aero,

Been doing some numbers and I'll post new ones in the morning for you if you wouldn't mind and are still interested.

Shell

Sure, I'd like to look more closely. Can't promise immediate response but the more I noodle it ahead of time the less time it will actually take to code the software.
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Offline WarpTech

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Regarding resonant modes in the frustum. Would there still be resonant modes if;

1. the frustum were open on the big end only?

2. the frustum were open on both ends?

IF I understand these modes correctly, the TExx0 modes resonate with the pointing vector radial in/out-ward from the axis to the walls. It seems to me, that a cone that is open on both ends would still support the same TEnm modes, just not the p modes. Correct?

If it's closed at the small end, it should still support odd harmonics of p modes. Correct?

Thank you!
Todd

It's interesting to think that in both the plastic bottles resonating with sound, and in our copper frustum resonating with microwaves, the wavelength is much longer than the size of the resonating device. A traditional microwave plane-wave doesn't exactly fit inside the wave guide (assuming resonant frequency), yet it resonates based on the properties of the device just like the air does inside a bottle. In the case of air, the resonant frequency of the plastic is important because it acts like a spring converting external perturbation into internal pressure changes by expanding and contracting with the same period as the sound waves.

In the case of our frustum, the energy going in is not a longitudinal wave like it is with sound(right?), however waveguides do some strange stuff with wave propagation. is there even such a thing as electromagnetic compression waves?

Maxwell would certainly seem to argue that electric field lines are always under constant tension and thus can't experience compression waves, however as a hobby armchair hand-waving expert myself I have spent a very long time trying to rectify that in my head with the fact that energy density warps the path of a photon (gravity) the same way a dielectric would warp the path of a photon and the same way that non-constant tension of electric field lines would warp the path of any wave. How can we say that energy distorts a field (gravity) but also say that the field has constant tension (Maxwell), when we know gravity distorts the path of a wave?

Add onto that the fact that waveguide wavelength is considerably longer than input wavelength, and the possibility that maybe photon path length changes were measured by an interferometer and it all starts to feel very much like electromagnet compression waves to me.

I'd love for someone to explain to me exactly why this is crazy.

Online aero

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Regarding resonant modes in the frustum. Would there still be resonant modes if;

1. the frustum were open on the big end only?

2. the frustum were open on both ends?

IF I understand these modes correctly, the TExx0 modes resonate with the pointing vector radial in/out-ward from the axis to the walls. It seems to me, that a cone that is open on both ends would still support the same TEnm modes, just not the p modes. Correct?

If it's closed at the small end, it should still support odd harmonics of p modes. Correct?

Thank you!
Todd

I don't know if a resonant mode can be found with both ends totally open but I do know that the Brady cavity will resonate nicely with the big end cap radius ~ 20% shorter than the big end cavity radius. That is, with a huge gap around the rim in the big end.
Retired, working interesting problems

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