Author Topic: EM Drive Developments - related to space flight applications - Thread 3  (Read 1872653 times)

Offline Star One

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Roger Shawyer's IAC 2014 paper has been peer reviewed and accepted for publication in Acta Astronautica, the IAF journal.

So , is the "2015 peer reviewed paper" that was going to "end all doubt"  the same IAC 2014 paper he presented at the 2014 conference?

Or is there something new in the Acta Astronautica version that was not present in the 2014 presentation?

What is in the document has been peer reviewed.

If you have any doubts about the validity of the comments in the paper, take it up with Acta Astronautica and their peer reviewers.

Have attached a few comments from the paper. Comments that are now peer reviewed.

What prompted your aggressive Non-Sequitur "If you have any doubts about the validity of the comments in the paper, take it up with Acta Astronautica and their peer reviewers." ? there was nothing in my question about doubts about  validity of anything.  I just asked about whether there was something new in the peer-reviewed paper as you had previously written that the 2015 peer-reviewed paper was going "to remove all doubt"

This is a statement ("to remove all doubt") you made, not that Shawyer made or anything to do with Acta Astronautica.  I simply don't understand how can a paper already presented in 2014 is going to "remove all doubt" when re-published in 2015, so I was asking whether there was something new in the re-publication that was going to remove all doubts in 2015 that were still lingering from the 2014 presentation. 

If it was going to remove all doubt it should have removed it in 2014 when originally presented, not when re-published in 2015, practically a year later.

Surely a more positive response was expected to a paper actually getting peer reviewed, which is surely a good development, rather than immediately giving him the fifth degree which is how your post appeared. Maybe that's not how it meant to come across, but it did rather read that way.
« Last Edit: 07/07/2015 02:09 PM by Star One »

Offline rfmwguy

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So, trying to grasp all theories here lead me to plasmons then to landau damping: https://en.m.wikipedia.org/wiki/Landau_damping and langmuir waves: https://en.m.wikipedia.org/wiki/Plasma_oscillation.

https://en.m.wikipedia.org/wiki/File:Phys_interp_landau_damp.svg

"It is possible to imagine Langmuir waves as waves in the sea, and the particles as surfers trying to catch the wave, all moving in the same direction. If the surfer is moving on the water surface at a velocity slightly less than the waves he will eventually be caught and pushed along the wave (gaining energy), while a surfer moving slightly faster than a wave will be pushing on the wave as he moves uphill (losing energy to the wave)."

Gaining energy can be viewed as gaining vector velocity I believe. What struck me is previous assertions about an emdrive needing an inertial "nudge" from a "motionless" reference frame.

Math wizards and maybe naysayers might want to look at the formulas to see if there is any correlation that can be made...we're talking particle and wave interactions yielding acceleration...not exactly my major in college ;)
Well here is a primer from recommended reading from Doc Rodal himself, the man is trying his darndest to burn my gray matter up. Even if you read the very well written text and ignore the pigeon scratchings it can help a lot. I've read it once and will be refreshing by reading again.
Shell
@shell

Small world, SLAC used to be a customer of mine back in the day for passives. This is particle and wave interaction at its finest...Megavolt...whoa. At first glance, it seems like an ion engine on steroids. Perhaps not applicable to our testing, but does show the energy possible using EM and particle interactions. Still stuck in theory about this. An rf source produces the wave action, where do the particles come from if indeed we are seeing force presented because of the interaction?

I do have some concern about poynting vectors yielding motion. While PV is directional pressure (potential outside a physical conductor), seems to me that the pressure is useless unless its applied against something. Some could argue the force is applied against the irradiator itself...I'm just too lame to visualize the concept at the moment...and I must visualize before putting pen to paper. A total net pointing vector of a system seems to yield a balance or zero force due to CoE.

Unless...we don't grasp all of the properties of a free space medium, which I think is a given.

Offline Rodal

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@shell

Small world, SLAC used to be a customer of mine back in the day for passives. This is particle and wave interaction at its finest...Megavolt...whoa. At first glance, it seems like an ion engine on steroids. Perhaps not applicable to our testing, but does show the energy possible using EM and particle interactions. Still stuck in theory about this. An rf source produces the wave action, where do the particles come from if indeed we are seeing force presented because of the interaction?

I do have some concern about poynting vectors yielding motion. While PV is directional pressure (potential outside a physical conductor), seems to me that the pressure is useless unless its applied against something. Some could argue the force is applied against the irradiator itself...I'm just too lame to visualize the concept at the moment...and I must visualize before putting pen to paper. A total net pointing vector of a system seems to yield a balance or zero force due to CoE.

Unless...we don't grasp all of the properties of a free space medium, which I think is a given.
You can choose to look at a half-filled cup as being half empty or half full.

You can choose to state that a Poynting vector is useless unless it is applied against something, it will be dissipated as heat.  This I already stated repeatedly (that the Poynting vector can get dissipated into heat).

But you might also choose to view this as the fact that having something to push or pull against will be of no use unless pushing or pulling is being done.  And what we have shown again, is that:

* There is a net, non-zero Poynting vector over an integer number of periods.  This negates what Greg Egan showed, where he concluded that the Poynting vector is zero for an EM Drive.

* The Poynting vector is increasing with time.  This is required in more general situations (for radiation pressure all that is required is a non-zero average).  This is very significant.  It remains to be explored whether it is just a transient.

An imperfect analogy (a toy to think about, as all analogies are imperfect): It is like you saying: I see a ship and you have shown somebody is rowing, but I don't know whether there is some medium to row against.

Somebody else may see this as follows: oh this is significant, as even if the ship was on water, if there was no rowing, it would not be able to move.

You might say, well I am not satisfied because you still have not shown what makes the ship move.  To which I answer: Rome wasn't built in a day.   Certainly Rome wasn't built without laying the foundation and people, building it.  Saying "Rome cannot be built" and remaining in the forest will not build Rome.

People might say: oh, I am unsatisfied that a few people working part-time (away from their daily jobs, doing this while others watch TV) have not solved "the problem" in a few months  :)  .  To which I say, it took over 360 years for Fermat's last theorem to be proven.  I don't believe in prophesies stating that "people are not going to be able to show what is going on".  Eventually we will know.

« Last Edit: 07/07/2015 02:23 PM by Rodal »

Offline TheTraveller

It can not hurt to have different opinions, certainly not at this stage, where we, external observers, are still looking for confirmation that there is indeed a force developing inside the EMdrive.

At best there is "some indication", but far from conclusive. I can imagine R.Shawyer having a different point of view, because he's been spending many years on the topic.

One of the key elements to assess which of the theories fits best, will be the experimental setups that investigate the possible contribution of the side walls. If they contribute nothing, then Shawyer is more likely to have the right direction, if they contribute something (or everything) then Shawyer will have to reconsider part of his theory, i think.

Although the paper contains some new elements, I would rather have preferred some hardcore data on the 2nd generation engine, instead of linear projections of what might/could be possible based upon mathematical models that have yet to be confirmed by experiments.

I, fe, have a hard time believing that the Q will scale so linear as has been assumed, but I would gladly be proven wrong by an experiment that shows it can be done....


Starting to get worried about the NASA highpower test. If only P.Marchal was allowed to drop a few lines on the progress made there...

In regard to Paul March here it is, as good as it gets. Every NSF image and document Paul attached in a easy to view / review format:

https://drive.google.com/folderview?id=0B7kgKijo-p0ifi13QTRLNldVb2llY05DaU5XMXM1OHFrTHRYTlF3bWtKMVNKdTQyeGswTlE&usp=sharing

There is a lot of gold in there.
"As for me, I am tormented with an everlasting itch for things remote. I love to sail forbidden seas.”
Herman Melville, Moby Dick

Offline rfmwguy

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@shell

Small world, SLAC used to be a customer of mine back in the day for passives. This is particle and wave interaction at its finest...Megavolt...whoa. At first glance, it seems like an ion engine on steroids. Perhaps not applicable to our testing, but does show the energy possible using EM and particle interactions. Still stuck in theory about this. An rf source produces the wave action, where do the particles come from if indeed we are seeing force presented because of the interaction?

I do have some concern about poynting vectors yielding motion. While PV is directional pressure (potential outside a physical conductor), seems to me that the pressure is useless unless its applied against something. Some could argue the force is applied against the irradiator itself...I'm just too lame to visualize the concept at the moment...and I must visualize before putting pen to paper. A total net pointing vector of a system seems to yield a balance or zero force due to CoE.

Unless...we don't grasp all of the properties of a free space medium, which I think is a given.
You can choose to look at a half-filled cup as being half empty or half full.

You can choose to state that a Poynting vector is useless unless it is applied against something, it will be dissipated as heat.  This I already stated repeatedly (that the Poynting vector can get dissipated into heat).

But you might also choose to view this as the fact that having something to push or pull against will be of no use unless pushing or pulling is being done.  And what we have shown again, is that:

* There is a net, non-zero Poynting vector over an integer number of periods.  This negates what Greg Egan showed, where he concluded that the Poynting vector is zero for an EM Drive.

* The Poynting vector is increasing with time.  This is required in more general situations (for radiation pressure all that is required is a non-zero average).  This is very significant.  It remains to be explored whether it is just a transient.

It is like you saying: I see a ship and you have shown somebody is rowing, but I don't know whether there is some medium to row against.

Somebody else may see this as follows: oh this is significant, as even if the ship was on water, if there was no rowing, it would not be able to move.

You might say, well I am not satisfied because you still have not shown what makes the ship move.  To which I answer: Rome wasn't built in a day.   Certainly Rome wasn't built without laying the foundation and people working on it saying "Rome cannot be built" and remaining in the forest.
Well said doc...u can tell I'm a natural skeptic, which is only healthy to a certain point. I do think there is rowing going on, just cannot visualize against what. That is what keeps me interested. Speaking of which, time to finish the exoskeleton.

Offline SeeShells

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In the first paragraph of section 4 of this paper, they decompose the wave vector into time-like and space-like, orthogonal components. This is a more precise derivation of exactly what I am doing. The space-like component must shift mass to match the boundary conditions as the time-like component travels down the waveguide.

It seems you "believe" waveguides are linear and cannot deviate from this expectation. In the case of a tapered waveguide, it mimics gravity which is non-linear. So, I still do not see what is "wrong" with my equation. Although, now I do see a better way to derive it and reference it. Thank you!
Todd

Todd,

Thank you for pointing this out, as I had not read this paper.  You are right:

http://arxiv.org/abs/0708.3519

Photons inside a waveguide as massive particles
Zhi-Yong Wang1, Cai-Dong Xiong

Section 4 RELATIVISTIC QUANTUM-MECHANICAL EQUATION OF GUIDED PHOTONS

Quote
Eqs. (20) and (21) are expressed in the arbitrary coordinate system (associated with a frame wherefrom the waveguide is viewed along an arbitrary 3D spatial direction), they can be simplified in the coordinate system (associated with a frame wherefrom the waveguide is viewed along the x123{,,}aaa123{,,}eee3-axis, and then one has L3(,0,0,)xtxμ=and 12(0,,,0)mkkμη=).

This similar to what Dr. Notsosureofit was discussing from a long time ago, and I had a hard time grasping :)

I also tried to point out many a post ago in (I think) the last EM drive thread, that a standing wave might be interpretable as an 'exotic' type of dynamically created massive particle. This whole tapered frustum actually looks to me as if this geometry squeezed one side of this dynamically created exotic particle equivalent. Assuming this point of view, this squeezed dynamic particle should then react and try to escape the squeezing towards the wider end of the frustum, hence being sort of accelerated, while the equivalent but opposite impulse is being imparted towards the smaller frustum end. If this were the case, the type of squeezing reaction might even depend on the type of exotic particle equivalent that is being dynamically generated in terms of frequency, energy density and field distribution/modes. Just the same as static types of particles have different properties that particle physics knows.
Yes, yes yes! Perfect. What wonderfully weird actions within 1/3 of a wavelength are occurring by the antenna?  A action the can impart spin and momentum and mass to that virtual particle that is being created within the small endcap? It is a evanescent wave action generating first order forces! Evanescent waves can move MIE particles, gold spheres and even charge your cell phone! This isn't a small force we're imparting to the virtual massive particles,  this is an evanescent wave action can move particles (MIE spheres with billions of atoms). The poynting vectors which give the momentum and spin of the massive virtual a direction to "push" and that's to the large end.

They head out to the large (*edit) end imparting force but being virtual particles that cannot exist without a corresponding real field from the small end cap they decay and disappear back into the Quantum vacuum. This action doesn't violate anything by making a virtual massive particle at the antenna adding energy and direction and thrust towards the large cavity end and then decaying back into the Quantum Vacuum.

I read somewhere and it went like this...  short-lived high-mass force-carrier particles seem to violate the laws of conservation of energy and mass -- their mass just can't come out of nowhere!" They can and they do, they are a result of the Heisenberg Uncertainty principle.  These high-mass particles come into being and seem to escape the standard model's notice somehow.

These massive virtual particles don't violate COE, in the end of the small cavity within 1/3 wavelength. Assisted by the evanescent waves they come into existence, The poynting vectors give them direction and upon decaying their kinetic energy plus their mass is imparted to the Frustum giving it acceleration and thrust.

Another cup of coffee is needed. ElizabethGreen you want to pop in here if you're around, while I get a cup of coffee, I have an idea you are following me as well as WarpDrive and of course everyone else ;) ? This idea has been cooking for weeks and the parts of it keep falling into place.

Shell
mixed up big and little...me fix
« Last Edit: 07/07/2015 03:06 PM by SeeShells »

Offline SeeShells

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@shell

Small world, SLAC used to be a customer of mine back in the day for passives. This is particle and wave interaction at its finest...Megavolt...whoa. At first glance, it seems like an ion engine on steroids. Perhaps not applicable to our testing, but does show the energy possible using EM and particle interactions. Still stuck in theory about this. An rf source produces the wave action, where do the particles come from if indeed we are seeing force presented because of the interaction?

I do have some concern about poynting vectors yielding motion. While PV is directional pressure (potential outside a physical conductor), seems to me that the pressure is useless unless its applied against something. Some could argue the force is applied against the irradiator itself...I'm just too lame to visualize the concept at the moment...and I must visualize before putting pen to paper. A total net pointing vector of a system seems to yield a balance or zero force due to CoE.

Unless...we don't grasp all of the properties of a free space medium, which I think is a given.
You can choose to look at a half-filled cup as being half empty or half full.

You can choose to state that a Poynting vector is useless unless it is applied against something, it will be dissipated as heat.  This I already stated repeatedly (that the Poynting vector can get dissipated into heat).

But you might also choose to view this as the fact that having something to push or pull against will be of no use unless pushing or pulling is being done.  And what we have shown again, is that:

* There is a net, non-zero Poynting vector over an integer number of periods.  This negates what Greg Egan showed, where he concluded that the Poynting vector is zero for an EM Drive.

* The Poynting vector is increasing with time.  This is required in more general situations (for radiation pressure all that is required is a non-zero average).  This is very significant.  It remains to be explored whether it is just a transient.

An imperfect analogy (a toy to think about, as all analogies are imperfect): It is like you saying: I see a ship and you have shown somebody is rowing, but I don't know whether there is some medium to row against.

Somebody else may see this as follows: oh this is significant, as even if the ship was on water, if there was no rowing, it would not be able to move.

You might say, well I am not satisfied because you still have not shown what makes the ship move.  To which I answer: Rome wasn't built in a day.   Certainly Rome wasn't built without laying the foundation and people, building it.  Saying "Rome cannot be built" and remaining in the forest will not build Rome.

People might say: oh, I am unsatisfied that a few people working part-time (away from their daily jobs, doing this while others watch TV) have not solved "the problem" in a few months.  To which I say, it took over 360 years for Fermat's last theorem to be proven.  I don't believe in prophesies stating that "people are not going to be able to show what is going on".  Eventually we will know.

The glass is just as large as it needs to be to make this work. I see what your talking about Dr. Rodal and it fits very well when all the actions are put together.
Shell

Offline graybeardsyseng

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Once my EMDrive is working on the rotary test rig and the test data is published, full detailed plans, bill of material and suppliers lists will be made available at no cost.

The build will include machined spherical end plates, highly polished, ding & scratch free internal surfaces and optional silver with gold flash coating on all internal surfaces. Unloaded cavity Q, for the coated cavity, is expected to be well over 100,000. Df is around 0.95. This will be a very efficient cavity which will include internal antenna and impedance matching system.

I'm buying a lathe to machine the spherical end plates and end plate flanges, plus to make a mandrel for the 2mm thick frustum and to accurately roll/form it around the mandrel. The frustum butt join & end flanges will be silver soldered to ensure excellent electrical conductivity and strength.

Design will be air tight due to an O ring between the end flanges and the end plates. The frustum side wall will have a small air valve that will allow air to be pumped out and then back filled with dry N2 at various internal pressures. This will also allow internal frustum pressure to be monitored and recorded before, during and after test runs to avoid counter claims that the Force generated was due to hot air leaks.

While the build will not be that technically challenging, I MAY consider providing tested EMDrives at my material costs, to enable anyone who wishes to test an EMDrive to be able to do so without needing to build the device themselves.

Same for the rotary test rig and data collection system.

Please don't get me wrong, this offer will cost me considerable time and make $0 profit as I expect it will take at least 2 weeks to build, align, polish, overcoat and test each EMDrive.

Device will look like the Boeing Flight Thruster and operate at 2.45GHz from a narrow band Rf generator. No magnetrons required.

Once my test data is published, interested parties can contact me to discuss.

Traveller (hope you are feeling much better!) -

Several comments if you please -

 first,  please be most careful with the metal working lathe - they can bite bad - it is the only machine in my shop which has successfully taken a chunk out of my fingers not once but twice.  - as the saying goes - shame on me. 

second, I am glad to hear you are using a narrow band RF source.  I understand both the financial and potential technical reasons for using the ubiquitous 2.45 Ghz magnetrons, but I have a feeling that there may be some sharp frequency dependencies/interactions/"bumps in the road" around the design point which they may be masking or at least making harder to identify and quantify.   I also have a feeling that the wideband nature of the signal might possible obscure the characteristics of the drive in going from an "idling" type mode to a "thrusting" type mode, or perhaps shed more light on the existance and character of such modes.   Perhaps not but it would be nice to observe that cleanly.

third, I would like to encourage data collection by experimenters "off design" i.e. at frequencies seperated from the design point of the frustum, as well as modulated by various schemes.    I am NOT necessarily suggesting moving outside the "microwave" regions, but characterization of the DUT (device under test) in "off design" situation often helps in understanding how it operates at design point.  For instance, given a f0 design point of 2.45 Ghz.  it would be most interesting to test the behavior over several orders of magnitude - say from 200 Mhz through 25 Ghz.   What do I expect to see?  'Expect' is likely too strong a word but it would be interesting to see if the device exhibits any sort of tendency to pull to its design point and lock up.  Or perhaps it is only metastable at the design point and requires active control to maintain efficent operation.   Or are there stable "off design" points where the device will operate - perhaps less efficently.  Without logical planned range testing it is difficult to know.   I have seen antennas and other RF systems exhibit some very weird behavior over the years and often careful, extensive testing was required to fully understand what was happening from a theoretical stance - and in particular if the EMDRIVE is to move to a practical space drive system.   I would also suggest such off design point simulations would be most interesting.

I recognized that a) we may not be ready for such testing just yet as there is much to be done to show that an actual artifact that can produce thrust exists, and b) there may be easier ways to do some of it (fixed RF source and mutiple or scaleable frustums (ala Seeshell's design).  But thinking about what sorts of future explorations can be done may influence the design of test units/DIY drives. 

Just some semi-random thoughts after the long weekend.

Herman


EMdrive - finally - microwaves are good for something other than heating ramen noodles and leftover pizza ;-)

Offline SeeShells

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@shell

Small world, SLAC used to be a customer of mine back in the day for passives. This is particle and wave interaction at its finest...Megavolt...whoa. At first glance, it seems like an ion engine on steroids. Perhaps not applicable to our testing, but does show the energy possible using EM and particle interactions. Still stuck in theory about this. An rf source produces the wave action, where do the particles come from if indeed we are seeing force presented because of the interaction?
Unless...we don't grasp all of the properties of a free space medium, which I think is a given.
Well said doc...u can tell I'm a natural skeptic, which is only healthy to a certain point. I do think there is rowing going on, just cannot visualize against what. That is what keeps me interested. Speaking of which, time to finish the exoskeleton.
I wrote that last part before my coffee for you rfmwguy, because I believed what I've been saying all along that the standard model forces need a link into the virtual world of particles and into the Quantum world effecting the local space/time environment of the frustum. In this model there are these three actions working together to rip virtual particles out of nothing (Heisenberg) and give them mass, energy, and force from the evanescent wave actions push and direction. So when every action needs a reaction the virtual particle pops into existence, imparts it's push energy and mass to the frustum and poof disappears back into the quantum world from where it came. It's like we're ripping up space/time by the antenna manipulating it a little pushing it out towards the rear of the cavity and watching it just disappear again after loosing all that made it in the first place.

(Warped Shell in the morning before any coffee actions) ;)

Shell

Offline TheTraveller

Once my EMDrive is working on the rotary test rig and the test data is published, full detailed plans, bill of material and suppliers lists will be made available at no cost.

The build will include machined spherical end plates, highly polished, ding & scratch free internal surfaces and optional silver with gold flash coating on all internal surfaces. Unloaded cavity Q, for the coated cavity, is expected to be well over 100,000. Df is around 0.95. This will be a very efficient cavity which will include internal antenna and impedance matching system.

I'm buying a lathe to machine the spherical end plates and end plate flanges, plus to make a mandrel for the 2mm thick frustum and to accurately roll/form it around the mandrel. The frustum butt join & end flanges will be silver soldered to ensure excellent electrical conductivity and strength.

Design will be air tight due to an O ring between the end flanges and the end plates. The frustum side wall will have a small air valve that will allow air to be pumped out and then back filled with dry N2 at various internal pressures. This will also allow internal frustum pressure to be monitored and recorded before, during and after test runs to avoid counter claims that the Force generated was due to hot air leaks.

While the build will not be that technically challenging, I MAY consider providing tested EMDrives at my material costs, to enable anyone who wishes to test an EMDrive to be able to do so without needing to build the device themselves.

Same for the rotary test rig and data collection system.

Please don't get me wrong, this offer will cost me considerable time and make $0 profit as I expect it will take at least 2 weeks to build, align, polish, overcoat and test each EMDrive.

Device will look like the Boeing Flight Thruster and operate at 2.45GHz from a narrow band Rf generator. No magnetrons required.

Once my test data is published, interested parties can contact me to discuss.

Traveller (hope you are feeling much better!) -

Several comments if you please -

 first,  please be most careful with the metal working lathe - they can bite bad - it is the only machine in my shop which has successfully taken a chunk out of my fingers not once but twice.  - as the saying goes - shame on me. 

second, I am glad to hear you are using a narrow band RF source.  I understand both the financial and potential technical reasons for using the ubiquitous 2.45 Ghz magnetrons, but I have a feeling that there may be some sharp frequency dependencies/interactions/"bumps in the road" around the design point which they may be masking or at least making harder to identify and quantify.   I also have a feeling that the wideband nature of the signal might possible obscure the characteristics of the drive in going from an "idling" type mode to a "thrusting" type mode, or perhaps shed more light on the existance and character of such modes.   Perhaps not but it would be nice to observe that cleanly.

third, I would like to encourage data collection by experimenters "off design" i.e. at frequencies seperated from the design point of the frustum, as well as modulated by various schemes.    I am NOT necessarily suggesting moving outside the "microwave" regions, but characterization of the DUT (device under test) in "off design" situation often helps in understanding how it operates at design point.  For instance, given a f0 design point of 2.45 Ghz.  it would be most interesting to test the behavior over several orders of magnitude - say from 200 Mhz through 25 Ghz.   What do I expect to see?  'Expect' is likely too strong a word but it would be interesting to see if the device exhibits any sort of tendency to pull to its design point and lock up.  Or perhaps it is only metastable at the design point and requires active control to maintain efficent operation.   Or are there stable "off design" points where the device will operate - perhaps less efficently.  Without logical planned range testing it is difficult to know.   I have seen antennas and other RF systems exhibit some very weird behavior over the years and often careful, extensive testing was required to fully understand what was happening from a theoretical stance - and in particular if the EMDRIVE is to move to a practical space drive system.   I would also suggest such off design point simulations would be most interesting.

I recognized that a) we may not be ready for such testing just yet as there is much to be done to show that an actual artifact that can produce thrust exists, and b) there may be easier ways to do some of it (fixed RF source and mutiple or scaleable frustums (ala Seeshell's design).  But thinking about what sorts of future explorations can be done may influence the design of test units/DIY drives. 

Just some semi-random thoughts after the long weekend.

Herman

Thanks for the comments.

Machine shops and I have been friends since I was a kid. Have had 2 lathes, 1st a woodie and then a really fine German metal lathe and never had an incident as I respect geared down HP. Do have a crease in the end of my finger where a table router blade taught me to ALWAYS use a pusher. As you say "Shame on Me".

Microwave kitchen magnetrons I believe are loss leaders in that they seem like a cheap source of a 1kW of microwave energy but come at a cost of the bandwidth which can be 60MHz or +-30MHz as Eagleworks measured in the attachment.

The dilemma is to fit all the microwave energy into the cavity, the cavity bandwidth must be at least 60MHz but then Q takes a really bit hit as 2,450,000,000 / 60,000,000 = ~41 which then says most of your microwave energy is not going to bounce much to generate much Force.

Much better to design a cavity with a Q of 100,000 (machine tolerance +- 0.05mm) that has a cavity bandwidth of +-12.5kHz and use a narrow band Rf gen that can also adjust frequency in 1kHz steps to get right into the middle of the cavities bandwidth window.

I plan to measure what I call Force bandwidth to explore how Force generation falls off as the frequency is slowly stepped in 1kHz steps across the cavity bandwidth and then plot the resultant Force bandwidth, which I feel will reveal a few interesting details.

Plan to build several cavities with different internal treatments to see the effect of Force generation and Force bandwidth versus coatings or not plus air filled, partial air vacuum, N2 filled, N2 filled at partial vacuum test runs.

Should be interesting.
« Last Edit: 07/07/2015 03:20 PM by TheTraveller »
"As for me, I am tormented with an everlasting itch for things remote. I love to sail forbidden seas.”
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Offline Rodal

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Trying to grasp the conjecture about vibration or ratcheting of the EM Drive and how best to ask Tajmar about it, and what should experimenters like RFMWGUY and Shell and DrBagelBytes do about it.

As I understand TheTraveller, he has decided the (only ?) satisfactory way to measure the elusive "EMDrive thrust" is to conduct an experiment on a rotating device mounted on a bearing. 

1) As I understand it, that means that he finds it unsatisfactory to measure the elusive "EMDrive thrust" not just using mechanical scales but also the teeter-totter and laser pointer that RFMWGUY and SeeShells and DrBagelBytes are planning to use.  Is that correct?

2) If that is so, what is the best thing that  RFMWGUY or SeeShells  or DrBagelBytes (or Tajmar or NASA)  can do to "motivate" the EM Drive with their set-up? Is it just to tap it? Or vibrating it, if so how, with what, at what frequency, amplitude and by how much?

3) How are testers going to strike a balance between eliminating background forces (the motion of the teeter totter that RFMWGUY and Dr.BagelBytes have shown due to air convection) and "motivating" the EM Drive?



« Last Edit: 07/07/2015 03:36 PM by Rodal »

Offline mwvp

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Some interesting stuff from:

"IAC-14-C4,8.5 SECOND GENERATION EMDRIVE PROPULSION APPLIED TO SSTO LAUNCHER AND INTERSTELLAR PROBE"

(Thank's Traveller)

Quote
...thrust generated in one direction and a reaction force in the
opposite direction. The acceleration measured on
the SPR Demonstrator engine was in the reaction
force direction, which was opposite to the thrust
initially measured on the static composite balance
test rig. Subsequent tests at SPR showed that both
thrust and reaction force could be measured on the
composite balance rig, by selection of different
spring constants.


Wow, measure two opposite thrusts depending on the spring-constant of your scale?!?!

Sounds like "negative inertial resistance" to me.

Different forces at each end (due to Vg), different consequent resonances with the setup mass, therefore different doppler-shifts excite different resonance amplitudes that determine which average thrust or reaction force gets measured.

And:

Quote
...To compensate for the decrease in
frequency due to the Doppler shift under
acceleration, the axial length of the cavityincreased by piezoelectric elements, mounted
between the side wall and the small end plate. The
voltage controlling the length of the piezoelectric
element is determined by a processor, fed by the
output of an accelerometer.

One of Shawyer's cones had a white-gasket like material, on the large end, I thought might be PZT.

Something Shawyer didn't address in the above paper is where the power goes that falls outside the cavity bandwidth. One would assume it is dissipated as heat. If an energized cavity tuning is changed, work is inserted or exctracted by physically re-tuning it, the energy changing frequency accordingly.

Offline deuteragenie

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* There is a net, non-zero Poynting vector over an integer number of periods.  This negates what Greg Egan showed, where he concluded that the Poynting vector is zero for an EM Drive.

Has this been demonstrated/accurately calculated? It has been shown that some slices of the data, when represented graphically appear to have large non-zeo Poynting vector.  I guess noone will object to this.  This does not mean that a) all slices (... infinitesimally small) exhibit the same behavior and b) that the many small (again, infinitesimally small) Poynting vectors which may or may not be graphically represented do not cancel out the large ones which dwarf them graphically.  Or am I missing something ?

* The Poynting vector is increasing with time.  This is required in more general situations (for radiation pressure all that is required is a non-zero average).  This is very significant.  It remains to be explored whether it is just a transient.

Roughly the same comment on this, but added to the potential need to consider much longer and finer time steps.  Has this been taken into account?

Offline TheTraveller

Trying to grasp the conjecture about vibration or ratcheting of the EM Drive and how best to ask Tajmar about it, and what should experimenters like RFMWGUY and Shell and DrBagelBytes do about it.

As I understand TheTraveller, he has decided the (only ?) satisfactory way to measure the elusive "EMDrive thrust" is to conduct an experiment on a rotating device mounted on a bearing. 

1) As I understand it, that means that he finds it unsatisfactory to measure the elusive "EMDrive thrust" not just using mechanical scales but also the teeter-totter and laser pointer that RFMWGUY and SeeShells and DrBagelBytes are planning to use.  Is that correct?

2) If that is so, what is the best thing that  RFMWGUY or SeeShells  or DrBagelBytes (or Tajmar or NASA)  can do to "motivate" the EM Drive with their set-up? Is it just to tap it? Or vibrating it, if so how, with what, at what frequency, amplitude and by how much?

3) How are testers going to strike a balance between eliminating background forces (the motion of the teeter totter that RFMWGUY and Dr.BagelBytes have shown due to air convection) and "motivating" the EM Drive?

If the EMDrive is not free to accelerate, the limited compression distance for movement a scale may offer, offers little ability to show what it can really do when it is free to accelerate without constraint.

Scales will still show some Force generation but it may not be the best showing.

Unless the experimenter has gone to extreme lengths to eliminate vibration, vibration will be there. Additionally the big end will experience significant sound vibratory Force shoving it gently toward to small end, which will experience less sound vibratory Forces due to reduced surface area.

I believe the lack of sound vibratory forces action on the big end is why Eagleworks experienced reduce Force generation in a vacuum.
« Last Edit: 07/07/2015 04:06 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 TheTraveller

Some interesting stuff from:

"IAC-14-C4,8.5 SECOND GENERATION EMDRIVE PROPULSION APPLIED TO SSTO LAUNCHER AND INTERSTELLAR PROBE"

(Thank's Traveller)

Quote
...thrust generated in one direction and a reaction force in the
opposite direction. The acceleration measured on
the SPR Demonstrator engine was in the reaction
force direction, which was opposite to the thrust
initially measured on the static composite balance
test rig. Subsequent tests at SPR showed that both
thrust and reaction force could be measured on the
composite balance rig, by selection of different
spring constants.


Wow, measure two opposite thrusts depending on the spring-constant of your scale?!?!

Sounds like "negative inertial resistance" to me.

Different forces at each end (due to Vg), different consequent resonances with the setup mass, therefore different doppler-shifts excite different resonance amplitudes that determine which average thrust or reaction force gets measured.

And:

Quote
...To compensate for the decrease in
frequency due to the Doppler shift under
acceleration, the axial length of the cavityincreased by piezoelectric elements, mounted
between the side wall and the small end plate. The
voltage controlling the length of the piezoelectric
element is determined by a processor, fed by the
output of an accelerometer.

One of Shawyer's cones had a white-gasket like material, on the large end, I thought might be PZT.

Something Shawyer didn't address in the above paper is where the power goes that falls outside the cavity bandwidth. One would assume it is dissipated as heat. If an energized cavity tuning is changed, work is inserted or extracted by physically re-tuning it, the energy changing frequency accordingly.

As the Chinese built, there needs to be a rejected microwave energy dump (with heat radiators), the device to the right of the microwave distribution system.

Trust you enjoyed the following comments?

Especially the one showing if you build and excite the cavity properly, the spherical waves impart no Forces on the side walls as they are at right angles to the side walls. Nice effect.
« Last Edit: 07/07/2015 04:04 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 DrBagelBites

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Trying to grasp the conjecture about vibration or ratcheting of the EM Drive and how best to ask Tajmar about it, and what should experimenters like RFMWGUY and Shell and DrBagelBytes do about it.

As I understand TheTraveller, he has decided the (only ?) satisfactory way to measure the elusive "EMDrive thrust" is to conduct an experiment on a rotating device mounted on a bearing. 

1) As I understand it, that means that he finds it unsatisfactory to measure the elusive "EMDrive thrust" not just using mechanical scales but also the teeter-totter and laser pointer that RFMWGUY and SeeShells and DrBagelBytes are planning to use.  Is that correct?

2) If that is so, what is the best thing that  RFMWGUY or SeeShells  or DrBagelBytes (or Tajmar or NASA)  can do to "motivate" the EM Drive with their set-up? Is it just to tap it? Or vibrating it, if so how, with what, at what frequency, amplitude and by how much?

3) How are testers going to strike a balance between eliminating background forces (the motion of the teeter totter that RFMWGUY and Dr.BagelBytes have shown due to air convection) and "motivating" the EM Drive?

I can say that I plan to not be in the same room as the test equipment. All vents/cracks/access to airflow will be cut off and allowed to be stagnant for a few hours. Of course, there is still background noise that is going to be there regardless and will be accounted for in the measurements.

An idea for motivating the teeter-totter is a simple servo motor that pulls down on one end to set it in motion. It is exact, repeatable, and easily done from outside of the room.

-I

Offline RonM

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3) How are testers going to strike a balance between eliminating background forces (the motion of the teeter totter that RFMWGUY and Dr.BagelBytes have shown due to air convection) and "motivating" the EM Drive?

That is one of the things that bothers me about Shawyer's theory. Even with the rotating setup, how is the tester going to get good data. It will be even harder to reduce background forces on a rotating platform.

The thing that bothers me the most about Shawyer's theory is that no thrust is seen by a stationary drive. That's the same result you would get if EM drives didn't work at all.

Now I'm not saying Shawyer is wrong, it's just that maybe testing his theory is beyond the capacity of DIY testers. Perhaps some vibration is enough for some thrust, but different test rigs will have different levels of vibration resulting in different thrust measurements. As TheTraveller wrote, it could explain the lower thrust results by Eagleworks.

I would like to see EM drive testing for stationary horizontal setups to be rotated by say 30 to 60 degrees between test series. If the thrust changes as the drive position changes, that would indicate an interaction with the Earth's magnetic field.

In a rotating test rig, does the thrust vary based on the position of the drive? Are there enough data points during a test run to look into that question?

In vertical drive setups, changing the angle would show how drive orientation reacts with Earth's gravitational field. Of course, that would make measuring thrust more difficult.

To all the testers out there, be safe and good luck.

Offline Rodal

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Trying to grasp the conjecture about vibration or ratcheting of the EM Drive and how best to ask Tajmar about it, and what should experimenters like RFMWGUY and Shell and DrBagelBytes do about it.

As I understand TheTraveller, he has decided the (only ?) satisfactory way to measure the elusive "EMDrive thrust" is to conduct an experiment on a rotating device mounted on a bearing. 

1) As I understand it, that means that he finds it unsatisfactory to measure the elusive "EMDrive thrust" not just using mechanical scales but also the teeter-totter and laser pointer that RFMWGUY and SeeShells and DrBagelBytes are planning to use.  Is that correct?

2) If that is so, what is the best thing that  RFMWGUY or SeeShells  or DrBagelBytes (or Tajmar or NASA)  can do to "motivate" the EM Drive with their set-up? Is it just to tap it? Or vibrating it, if so how, with what, at what frequency, amplitude and by how much?

3) How are testers going to strike a balance between eliminating background forces (the motion of the teeter totter that RFMWGUY and Dr.BagelBytes have shown due to air convection) and "motivating" the EM Drive?

If the EMDrive is not free to accelerate, the limited compression distance for movement a scale may offer, offers little ability to show what it can really do when it is free to accelerate without constraint.

Scales will still show some Force generation but it may not be the best showing.

Unless the experimenter has gone to extreme lengths to eliminate vibration, vibration will be there. Additionally the big end will experience significant sound vibratory Force shoving it gently toward to small end, which will experience less sound vibratory Forces due to reduced surface area.

I believe the lack of sound vibratory forces action on the big end is why Eagleworks experienced reduce Force generation in a vacuum.
Concerning the upcoming presentation by Prof. Tajmar from The Technische Universität Dresden at the AIAA meeting, and assuming what I heard from several sources is correct that:

1) The Technische Universität Dresden measured less than 50 microNewtons force from the EM Drive with several hundred Watts in vacuum, under different orientations

2) That Tajmar doesn't know about the vibration/ratcheting conjecture to motivate the EM Drive thrust

how could someone like DrBagelBytes best ask Tajmar during his presentation at the AIAA meeting about whether Tajmar's University team measured such low forces due to the vibration/ratcheting conjecture to motivate the EM Drive thrust, in as few words as possible while simultaneously explaining to Tajmar at the Q/A session what this conjecture is all about?
« Last Edit: 07/07/2015 04:52 PM by Rodal »

Offline mwvp

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As the Chinese built, there needs to be a rejected microwave energy dump (with heat radiators), the device to the right of the microwave distribution system.

Ok. Thanks for pointing that out.

Trust you enjoyed the following comments?

Especially the one showing if you build and excite the cavity properly, the spherical waves impart no Forces on the side walls as they are at right angles to the side walls. Nice effect.

Very much, thank-you. As far as side wall forces, if there really were none, the EM (vacuum) mode would either be absorbed or radiate away into space  ;)

But I don't have a problem considering that they add to reaction force, and not null or balance out asymmetrical force.

Offline zen-in

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Roger Shawyer's IAC 2014 paper has been peer reviewed and accepted for publication in Acta Astronautica, the IAF journal.

I just finished reading this paper and don't believe any outstanding questions have been answered.  In the abstract Mr. Shawyer mentions a high temperature superconductor cavity.   There are dimensions and expectations of the performance of this HTS cavity but no mention of any experiments or any data that has been collected.   The rest of the paper is devoted to descriptions of hypothetical space drives and dubious math.   

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