Author Topic: EM Drive Developments - related to space flight applications - Thread 10  (Read 706714 times)

Offline Bob Woods

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Just out of curiosity - why haven't anyone tested with array of thrusters/fustrums?

It seems from the thread that the biggest issue for current and past tests is detecting reliable thrust signal from the background noise. Yet all developments have tried either to eliminate the noise sources.. or to elevate the power levels (also bringing up the background noise), but not adding to the thrust by adding thrusters.

Yet - if I understand correctly - thrust is expected to come from the fustrum and it should not be extremely hard to place 2 or 4 fustrums on the torsion balance. Yes, it would elevate the weight - but would also multiply the thrust signal while leaving feeding system and overall design pretty much the same. One would also be able to switch on fustrums independently, getting additional thrust with each additional fustrum powered up, that should be visible from analysis. In theory it would also be possible to add thrusters on both sides of torsion balance, adding to the stability of the system..

Think of an emDrive array as an array of radios or cellphones. One is affordable to work with; duplicating two more requires getting the first one right.

Arrays add another layer of complexity and assume the thrust elements can reliably produce thrust. In order to develop an array of units aka elements,  at the array level one has to duplicate all the testing for a single thruster, most importantly, electromagnetic compatibility, acceleration and thermal (aka EM, shake and bake).

Generally, the goal is a single unit would provide enough mission-level impulse (thrust x time). MilliNewtons per unit is helpful. Newtons would desirable.

The thrust is developed from amplified effects and powered by one or more energy storage devices, typically a battery or large capacitor. From solar to nuclear, other power sources are possible

Arrays are used for both multiplying thrust to mission level requirements especially when amplification methods have reached a maximum. Other uses of arrays include to provide throttling, positioning and steering.

Testing emDrives in arrays assumes one has the time and resources to build identical units to populate an array and continuously put out thrust in space.

Thrust levels per unit have to be in the millinewton range at a minimum.

Size and weight have to be minimized, and electric power efficiency - from generated vs delivered - has to be quite significant. For any thruster system, measures include Thrust per volume in cubic meters (ft^3), thrust per mass in kg (lb), and thrust per power, N/kWe (lb-force).

Cooling the power& propulsion system needs to be considered and adds to weight and volume of the basic emDrive since a basic emDrive is roughly 1 cubic foot ~12" on a side  ~30 cm, the power supply has to be portable, the electromagnetic compatibility -both emission and susceptibility - has to be determined for a single unit before producing multiples.

The unit drive is an element in an array, typically a linear or planar array. Linear arrays are 1D arrays with two orientations - inline (stack) and lateral (wing). A planar array can duplicated to become one of many boards stacked in a box typically secured on three or four sides; a box-of-boards array is a 2.5 D array.

In any array configuration, an additional requirement to emDrive testing is to determine if there are any E&M emissions from another emDrive that would impair operation of any drive. At the present time, there is no data to support emDrive to emDrive coupling.

The question of 3D arrays involves a framework structure. The first step would be to test at the 2.5 D level with Boards in a Box (BIB) array. In any BIB array or 3D framework structure, any absorption or emission by the structure needs to be considered including acoustic, thermal, RF, particle and fields.

A minor point...a good theory would be extremely helpful to explain the behavior of the emDrive.  While some folks "shut up and calculate", the presumptions are that one has data to calculate, and that the design/build was based on at least some theoretical conjecture instead of flights of fancy.

An array may require a team effort on many levels as well as in production of units. A collaborative effort could  build an array if a specification can be agreed to and funding can be obtained.

Other than that, it's easy.

David
Another couple of points...


Once a test series is completed in atmosphere, a follow-up then is testing in a vacuum chamber. Unless you have lot's of cash, most test rigs will need to fit within a relatively small vacuum chamber as NASA Eagleworks did. Arrays of frustums the size of Monomorphic's would require a much larger vacuum chamber to fit in, as I understand it.


In threads back it was my recollection that no one who tried to build a small frustum was able to detect thrust. The hypothesis was that smaller frustums with much shorter wavelengths of radiation might produce higher orders of thrust, but it was not seen. TE013 modes in Mono's frustum design have  a wavelength of 2.449 GHZ, which is about the same as microwave oven magnetrons at 2.45 GHZ, which is where these DYI experiments started and thrust may have been generated.

Offline spupeng7


(...)
 The contending interpretations, differing over whether quantum mechanics can be understood to be deterministic, which elements of quantum mechanics can be considered "real", and other matters, are more important to problems with single photons, rather than a problem like the EM Drive where one has a huge amount of photons, and therefore there are no apparent issues that arise from using the instrumentalist approach, because for a problem involving a huge amount of photons, all the mentioned interpretations should lead to the same calculated answer.

Rather than having a philosophical debate, if you (or others) disagree, please let us know what difference in the calculation of the EM Drive any of these interpretations can possible make.  Tell us about the calculation (not philosophical differences) pertaining to the EM Drive experiments  ;)  [not other experiments: not single photon, not double slit, not quantum entanglement, etc., but just the EM Drive experiment please]

Again, I expect that a number of people in the audience are very interested in philosophy and history of physics, and I am not criticizing such endeavors, which I agree are indeed quite worthwhile.  I am just asking people that write about the importance of these interpretations to teach me (us ?) what difference it can possibly make for calculations of the EM Drive Developments -related to space flight applications (not for other fundamental physical problems for which one may differentiate between the calculated responses from different interpretations  !!! )
Rodal, if you will forgive a philosophical reply,
       if all charges continually interact electrically, then there is a huge difference between the potential for remote interaction which that indicates and the dearth of interactive potential which all objects which are in sum, neutral, have with respect to distant matter when it is only their overall neutrality which is considered.
       Time dilation acts upon charges individually, not upon macroscopic objects in totality. Non? Am of course looking for help calculating this difference for an emdrive frustum (I don't believe any engineer should rely on unchecked method or calculation  :) )
Optimism equals opportunity.

Offline JasonAW3

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Interesting development;


      I'm uncertain as to whether or not that this may have any bearing on this discussion, but the effect is interesting;

https://newatlas.com/negative-mass-particles/52848/

      The "negative mass" effect seems similar to some of what appears to be going on with the EM drive.
My God!  It's full of universes!

Offline Rodal

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Interesting development;


      I'm uncertain as to whether or not that this may have any bearing on this discussion, but the effect is interesting;

https://newatlas.com/negative-mass-particles/52848/

      The "negative mass" effect seems similar to some of what appears to be going on with the EM drive.

Not an EM Drive [radio frequency asymmetric, empty, copper cavity] as conceived by Shawyer or as tested by EM Drive testers so far.

Actual paper:

https://www.nature.com/articles/nphys4303.pdf

Optically resonant cavities involving nanoscale light–matter interactions obtained by embedding a single layer of an atomically thin semiconductor (molybdenum diselenide = MoSe2) in a monolithic optical cavity based on distributed Bragg reflectors. (A monolayer of MoSe2 is embedded between the top and bottom distributed Bragg reflectors).



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

https://en.wikipedia.org/wiki/Polariton
.
https://en.wikipedia.org/wiki/Optical_cavity

https://en.wikipedia.org/wiki/Distributed_Bragg_reflector
« Last Edit: 01/08/2018 05:36 PM by Rodal »

Offline Rodal

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FYI:

Acta Astronautica
Articles in Press


Comments on theoretical foundation of “EM Drive”

In Press, Accepted Manuscript, Available online 4 January 2018
C.-W. Wu
-------
Highlights

The theoretical derivation of the net thrust in “EM drive” is found to be inaccurate.

Self-contradiction in physics is found in the concept of “EM drive”.

The theoretical foundation of the “EM drive” is found to be not solid.

Here is the link:

https://www.sciencedirect.com/science/article/pii/S0094576517317356


"Comments on theoretical foundation of “EM Drive” "
C.-W. Wu

Institute of Mechanics, Chinese Academy of Sciences, No.15 BeisihuanXi Road, Beijing 100190, China
Received 24 November 2017, Revised 29 December 2017, Accepted 4 January 2018, Available online 4 January 2018

Abstract
Quote
The concept of EM Drive has attracted much attention and groups of work have been conducted to prove or verify it, of which the published experimental outcome is criticized in great details while the theoretical foundation has not been discussed. The present essay investigates on the theoretical derivations of the net thrust in the “EM drive” and reveals the self-contradiction arising at the very start, when the law of conservation of momentum was utilized and opposed simultaneously.

pdf Article is behind $35.95 paywall

article contains one figure: 





Recall that Acta Astronautica was the peer-reviewed publication where Roger Shawyer published this article in 2015:

http://www.emdrive.com/IAC14publishedpaper.pdf

Acta Astronautica 116 (2015) 166–174

"Second generation EmDrive propulsion applied to SSTO launcher and interstellar probe"
Roger Shawyer


Actual paper can now be read for free as uploaded by the author (C.W. Wu) on Jan 06, 2018:

https://www.researchgate.net/publication/322261866_Comments_on_theoretical_foundation_of_EM_Drive

(click on download link on the upper right hand corner of the above webpage)
« Last Edit: 01/08/2018 07:23 PM by Rodal »

Offline SteveD

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Interesting development;


      I'm uncertain as to whether or not that this may have any bearing on this discussion, but the effect is interesting;

https://newatlas.com/negative-mass-particles/52848/

      The "negative mass" effect seems similar to some of what appears to be going on with the EM drive.

Not an EM Drive [radio frequency asymmetric, empty, copper cavity] as conceived by Shawyer or as tested by EM Drive testers so far.

Actual paper:

https://www.nature.com/articles/nphys4303.pdf

Optically resonant cavities involving nanoscale light–matter interactions obtained by embedding a single layer of an atomically thin semiconductor (molybdenum diselenide = MoSe2) in a monolithic optical cavity based on distributed Bragg reflectors. (A monolayer of MoSe2 is embedded between the top and bottom distributed Bragg reflectors).



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

https://en.wikipedia.org/wiki/Polariton
.
https://en.wikipedia.org/wiki/Optical_cavity

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

Is this negative mass as in an Alcubbier drive or is it using negative mass to describe some other phenomenon?

Online RotoSequence

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I've had a thought in the back of my mind for some time now that it might be interesting to see what happens to an EM Drive cavity if you run a current through the resonant cavity before and while injecting it with RF, just to see if there are some interesting dynamics that come from it. Anomalous dispersion and other phenomena don't make that inkling go away.  8)

Offline Rodal

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Quote from: SteveD link=topic=42978.msg1769764#msg1769764 date1515564065
...
Is this negative mass as in an Alcubbier drive or is it using negative mass to describe some other phenomenon?
The article does not deal with mass of a macroscopic body.  Instead the article deals with the concept of "effective mass" as used in solid-state physics, more specifically in this case "effective mass" of quantum mechanical quasiparticles.  See:  https://en.wikipedia.org/wiki/Effective_mass_(solid-state_physics)

Quote
In solid state physics, a particle's effective mass... is the mass that it seems to have when responding to forces, or the mass that it seems to have when interacting with other identical particles in a thermal distribution. One of the results from the band theory of solids is that the movement of particles in a periodic potential, over long distances larger than the lattice spacing, can be very different from their motion in a vacuum. The effective mass is a quantity that is used to simplify band structures by modeling the behavior of a free particle with that mass. For some purposes and some materials, the effective mass can be considered to be a simple constant of a material. In general, however, the value of effective mass depends on the purpose for which it is used, and can vary depending on a number of factors.
...
At the highest energies of the valence band in many semiconductors (Ge, Si, GaAs, ...), and the lowest energies of the conduction band in some semiconductors (GaAs, ...), the band structure E(k) can be locally approximated as




where E(k) is the energy of an electron at wavevector k in that band, E0 is a constant giving the edge of energy of that band, and m* is a constant (the effective mass).

It can be shown that the electrons placed in these bands behave as free electrons except with a different mass, as long as their energy stays within the range of validity of the approximation above. As a result, the electron mass in models such as the Drude model must be replaced with the effective mass.

One remarkable property is that the effective mass can become negative, when the band curves downwards away from a maximum. As a result of the negative mass, the electrons respond to electric and magnetic forces by gaining velocity in the opposite direction compared to normal; even though these electrons have negative charge, they move in trajectories as if they had positive charge (and positive mass). This explains the existence of valence-band holes, the positive-charge, positive-mass quasiparticles that can be found in semiconductors.

In any case, if the band structure has the simple parabolic form described above, then the value of effective mass is unambiguous. Unfortunately, this parabolic form is not valid for describing most materials. In such complex materials there is no single definition of "effective mass" but instead multiple definitions, each suited to a particular purpose. The rest of the article describes these effective masses in detail.

These polaritons are quantum mechanical quasiparticles (https://en.wikipedia.org/wiki/Quasiparticle) which are used to describe interactions in a solid.  They are bosonic quasiparticles resulting from strong coupling of electromagnetic waves with an electric or magnetic dipole‐carrying excitation.  The article describes a type of polariton called exciton‐polariton: resulting from the coupling of photons of visible light with an exciton  (an electron and hole bound together: https://en.wikipedia.org/wiki/Exciton ) .  The authors describe an effective mass as given by the equation at the bottom of the first column on page 3 of https://www.nature.com/articles/nphys4303.pdf : due to the second derivative of the energy E with respect to the wavevector k.  Also see the analogous equation here for the effective mass tensor:  https://en.wikipedia.org/wiki/Effective_mass_(solid-state_physics)#Inertial_effective_mass_tensor



where ħ = h/2π is the reduced Planck constant and ki and kj are the ith and jth components of the wavevector k, respectively, and E is the total energy of the quasiparticle

and note:

Quote
The inertial expression for effective mass is commonly used, but note that its properties can be counter-intuitive:

The effective mass tensor generally varies depending on k, meaning that the mass of the particle actually changes after it is subject to an impulse. The only cases in which it remains constant are those of parabolic bands, described above.
The effective mass tensor diverges (becomes infinite) for linear dispersion relations, such as with photons or electrons in graphene. (These particles are sometimes said to be massless, however this refers to their having zero rest mass; rest mass is a distinct concept from effective mass.)

Also, most importantly, note that the "acceleration" in this definition is the rate of change of the group velocity:






The second derivative of a function describes its curvature and therefore one can associate this "effective mass" with the curvature of the energy of the polarization wave.  Regarding physical effects due to "negative mass" that might be observable, it is important to remark that the authors have not performed any push or pull experiments (and it is not clear yet whether or how could such experiments be conducted: we are dealing with quasiparticles).

See page 776 of this book:  http://bit.ly/2Eu28J9

Confined Electrons and Photons: New Physics and Applications
edited by Elias Burstein, Claude Weisbuch
Hardcover: 907 pages
Publisher: Springer; 1995 edition (May 31, 1995)
Language: English
ISBN-10: 0306449900
ISBN-13: 978-0306449901

The spatial dispersion (https://en.wikipedia.org/wiki/Spatial_dispersion) relation for real wave vectors for polaritons can result in a positive "mass" (Fig 4a) or a "negative mass" (Fig4b) case, depending on the sign of the curvature of the energy vs the wavevector. The "effective mass" being discussed is a measure of the (second derivative or) curvature of the uncoupled polarization wave.
« Last Edit: 01/10/2018 11:32 PM by Rodal »

Offline Monomorphic

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The weather was so cold for so long that I could not keep the lab area above 65F (18C), even with the new space heater. Now that more moderate temperatures have returned, I was able to get some work done. Adding insulation to the torsional pendulum beam seems to have greatly improved the signal -to-noise ratio (SNR). Before I had only insulated the aluminum support and draft enclosure. I also increased the on-board computer storage from 32GB to 64GB.

The cavity is still on the workbench as I plan on recording a video showing how impedance is matched and the cavity length is tuned for maximum resonance.
« Last Edit: 01/11/2018 11:44 AM by Monomorphic »

Offline dustinthewind

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Quote from: SteveD link=topic=42978.msg1769764#msg1769764 date1515564065
...
Is this negative mass as in an Alcubbier drive or is it using negative mass to describe some other phenomenon?
The article does not deal with mass of a macroscopic body.  Instead the article deals with the concept of "effective mass" as used in solid-state physics, more specifically in this case "effective mass" of quantum mechanical quasiparticles.  See:  https://en.wikipedia.org/wiki/Effective_mass_(solid-state_physics)

Quote
In solid state physics, a particle's effective mass... is the mass that it seems to have when responding to forces, or the mass that it seems to have when interacting with other identical particles in a thermal distribution. One of the results from the band theory of solids is that the movement of particles in a periodic potential, over long distances larger than the lattice spacing, can be very different from their motion in a vacuum. The effective mass is a quantity that is used to simplify band structures by modeling the behavior of a free particle with that mass. For some purposes and some materials, the effective mass can be considered to be a simple constant of a material. In general, however, the value of effective mass depends on the purpose for which it is used, and can vary depending on a number of factors.
...
At the highest energies of the valence band in many semiconductors (Ge, Si, GaAs, ...), and the lowest energies of the conduction band in some semiconductors (GaAs, ...), the band structure E(k) can be locally approximated as




where E(k) is the energy of an electron at wavevector k in that band, E0 is a constant giving the edge of energy of that band, and m* is a constant (the effective mass).

It can be shown that the electrons placed in these bands behave as free electrons except with a different mass, as long as their energy stays within the range of validity of the approximation above. As a result, the electron mass in models such as the Drude model must be replaced with the effective mass.

One remarkable property is that the effective mass can become negative, when the band curves downwards away from a maximum. As a result of the negative mass, the electrons respond to electric and magnetic forces by gaining velocity in the opposite direction compared to normal; even though these electrons have negative charge, they move in trajectories as if they had positive charge (and positive mass). This explains the existence of valence-band holes, the positive-charge, positive-mass quasiparticles that can be found in semiconductors.

In any case, if the band structure has the simple parabolic form described above, then the value of effective mass is unambiguous. Unfortunately, this parabolic form is not valid for describing most materials. In such complex materials there is no single definition of "effective mass" but instead multiple definitions, each suited to a particular purpose. The rest of the article describes these effective masses in detail.

These polaritons are quantum mechanical quasiparticles (https://en.wikipedia.org/wiki/Quasiparticle) which are used to describe interactions in a solid.  They are bosonic quasiparticles resulting from strong coupling of electromagnetic waves with an electric or magnetic dipole‐carrying excitation.  The article describes a type of polariton called exciton‐polariton: resulting from the coupling of photons of visible light with an exciton  (an electron and hole bound together: https://en.wikipedia.org/wiki/Exciton ) .  The authors describe an effective mass as given by the equation at the bottom of the first column on page 3 of https://www.nature.com/articles/nphys4303.pdf : due to the second derivative of the energy E with respect to the wavevector k.  Also see the analogous equation here for the effective mass tensor:  https://en.wikipedia.org/wiki/Effective_mass_(solid-state_physics)#Inertial_effective_mass_tensor



where ħ = h/2π is the reduced Planck constant and ki and kj are the ith and jth components of the wavevector k, respectively, and E is the total energy of the quasiparticle

and note:

Quote
The inertial expression for effective mass is commonly used, but note that its properties can be counter-intuitive:

The effective mass tensor generally varies depending on k, meaning that the mass of the particle actually changes after it is subject to an impulse. The only cases in which it remains constant are those of parabolic bands, described above.
The effective mass tensor diverges (becomes infinite) for linear dispersion relations, such as with photons or electrons in graphene. (These particles are sometimes said to be massless, however this refers to their having zero rest mass; rest mass is a distinct concept from effective mass.)

Also, most importantly, note that the "acceleration" in this definition is the rate of change of the group velocity:






The second derivative of a function describes its curvature and therefore one can associate this "effective mass" with the curvature of the energy of the polarization wave.  Regarding physical effects due to "negative mass" that might be observable, it is important to remark that the authors have not performed any push or pull experiments (and it is not clear yet whether or how could such experiments be conducted: we are dealing with quasiparticles).

See page 776 of this book:  http://bit.ly/2Eu28J9

Confined Electrons and Photons: New Physics and Applications
edited by Elias Burstein, Claude Weisbuch
Hardcover: 907 pages
Publisher: Springer; 1995 edition (May 31, 1995)
Language: English
ISBN-10: 0306449900
ISBN-13: 978-0306449901

The spatial dispersion (https://en.wikipedia.org/wiki/Spatial_dispersion) relation for real wave vectors for polaritons can result in a positive "mass" (Fig 4a) or a "negative mass" (Fig4b) case, depending on the sign of the curvature of the energy vs the wavevector. The "effective mass" being discussed is a measure of the (second derivative or) curvature of the uncoupled polarization wave.

I don't know if this is relevant but this reminded me that copper can be made into a solar cell by burning it till copper oxide forms. 

Could there be some asymmetric distribution of copper oxide inside the cavity via internal temperature or some other reason? - maybe arcing?

Something I found describing holes in copper oxide and change in effective mass: http://iopscience.iop.org/article/10.1088/0022-3719/9/8/014
Cyclotron resonance of electrons and of holes in cuprous oxide, Cu2O

something else below that may, or may not be of relevance.
https://atlasofscience.org/copper-oxide-for-low-cost-and-stable-perovskite-solar-cells/

Offline graybeardsyseng

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Just out of curiosity - why haven't anyone tested with array of thrusters/fustrums?

It seems from the thread that the biggest issue for current and past tests is detecting reliable thrust signal from the background noise. Yet all developments have tried either to eliminate the noise sources.. or to elevate the power levels (also bringing up the background noise), but not adding to the thrust by adding thrusters.

Yet - if I understand correctly - thrust is expected to come from the fustrum and it should not be extremely hard to place 2 or 4 fustrums on the torsion balance. Yes, it would elevate the weight - but would also multiply the thrust signal while leaving feeding system and overall design pretty much the same. One would also be able to switch on fustrums independently, getting additional thrust with each additional fustrum powered up, that should be visible from analysis. In theory it would also be possible to add thrusters on both sides of torsion balance, adding to the stability of the system..

Think of an emDrive array as an array of radios or cellphones. One is affordable to work with; duplicating two more requires getting the first one right.

Arrays add another layer of complexity and assume the thrust elements can reliably produce thrust. In order to develop an array of units aka elements,  at the array level one has to duplicate all the testing for a single thruster, most importantly, electromagnetic compatibility, acceleration and thermal (aka EM, shake and bake).

Generally, the goal is a single unit would provide enough mission-level impulse (thrust x time). MilliNewtons per unit is helpful. Newtons would desirable.

The thrust is developed from amplified effects and powered by one or more energy storage devices, typically a battery or large capacitor. From solar to nuclear, other power sources are possible

Arrays are used for both multiplying thrust to mission level requirements especially when amplification methods have reached a maximum. Other uses of arrays include to provide throttling, positioning and steering.

Testing emDrives in arrays assumes one has the time and resources to build identical units to populate an array and continuously put out thrust in space.

Thrust levels per unit have to be in the millinewton range at a minimum.

Size and weight have to be minimized, and electric power efficiency - from generated vs delivered - has to be quite significant. For any thruster system, measures include Thrust per volume in cubic meters (ft^3), thrust per mass in kg (lb), and thrust per power, N/kWe (lb-force).

Cooling the power& propulsion system needs to be considered and adds to weight and volume of the basic emDrive since a basic emDrive is roughly 1 cubic foot ~12" on a side  ~30 cm, the power supply has to be portable, the electromagnetic compatibility -both emission and susceptibility - has to be determined for a single unit before producing multiples.

The unit drive is an element in an array, typically a linear or planar array. Linear arrays are 1D arrays with two orientations - inline (stack) and lateral (wing). A planar array can duplicated to become one of many boards stacked in a box typically secured on three or four sides; a box-of-boards array is a 2.5 D array.

In any array configuration, an additional requirement to emDrive testing is to determine if there are any E&M emissions from another emDrive that would impair operation of any drive. At the present time, there is no data to support emDrive to emDrive coupling.

The question of 3D arrays involves a framework structure. The first step would be to test at the 2.5 D level with Boards in a Box (BIB) array. In any BIB array or 3D framework structure, any absorption or emission by the structure needs to be considered including acoustic, thermal, RF, particle and fields.

A minor point...a good theory would be extremely helpful to explain the behavior of the emDrive.  While some folks "shut up and calculate", the presumptions are that one has data to calculate, and that the design/build was based on at least some theoretical conjecture instead of flights of fancy.

An array may require a team effort on many levels as well as in production of units. A collaborative effort could  build an array if a specification can be agreed to and funding can be obtained.

Other than that, it's easy.

David
Another couple of points...


Once a test series is completed in atmosphere, a follow-up then is testing in a vacuum chamber. Unless you have lot's of cash, most test rigs will need to fit within a relatively small vacuum chamber as NASA Eagleworks did. Arrays of frustums the size of Monomorphic's would require a much larger vacuum chamber to fit in, as I understand it.


In threads back it was my recollection that no one who tried to build a small frustum was able to detect thrust. The hypothesis was that smaller frustums with much shorter wavelengths of radiation might produce higher orders of thrust, but it was not seen. TE013 modes in Mono's frustum design have  a wavelength of 2.449 GHZ, which is about the same as microwave oven magnetrons at 2.45 GHZ, which is where these DYI experiments started and thrust may have been generated.

Bob and Augmentor

Excellent points both of you -

Just one MORE fun challenge I would add - since we don't know what the  underlying theory of EMdrive is(assuming there is one) we can't assume effects are additive at all or how they will sum.   Generally arrays of antennas or other RF systems must be modeled and tuned carefully as there ARE interactions between individual components, not to mention support structure etc.   Those can be modeled and simulated (e.g. a vertical stack of yagi's or a beam forming array for a electrically steerable radar) BECAUSE we understand (at least pretty well heh heh ) how they work.   

Now, personally, I strongly SUSPECT that, if EMDrive is real and produces thrust, then any practical application likely WILL be an array of 'thrusters', particularly if used as primary delta V source - although  steering/stationkeeping might be able to be accomplished with practically realizable single thrusters (again assuming there ARE such things as practically realizable thrusters).

N. B.  This suspicion  is a completely NON Scientific viewpoint based on work experience - i.e. it is a GUESS with some history behind it a.k.a. "engineering judgment" . . . so take it with a supersized grain of doubt. 

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

Offline R.W. Keyes

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 (lots cut for the sake of brevity )

Just one MORE fun challenge I would add - since we don't know what the  underlying theory of EMdrive is(assuming there is one) we can't assume effects are additive at all or how they will sum.   Generally arrays of antennas or other RF systems must be modeled and tuned carefully as there ARE interactions between individual components, not to mention support structure etc.   Those can be modeled and simulated (e.g. a vertical stack of yagi's or a beam forming array for a electrically steerable radar) BECAUSE we understand (at least pretty well heh heh ) how they work.   

That's possible, but not likely, by my reckoning. An EMDrive would have to convert all of its EMfields to thrust in order to be efficient. Any leakage would appear as heat.

Now, personally, I strongly SUSPECT that, if EMDrive is real and produces thrust, then any practical application likely WILL be an array of 'thrusters', particularly if used as primary delta V source - although  steering/stationkeeping might be able to be accomplished with practically realizable single thrusters (again assuming there ARE such things as practically realizable thrusters).

N. B.  This suspicion  is a completely NON Scientific viewpoint based on work experience - i.e. it is a GUESS with some history behind it a.k.a. "engineering judgment" . . . so take it with a supersized grain of doubt. 

When you say "array", consider that such an array would be 3D. Without specific inter-EM drive interaction, then EMdrives could be placed outside of a specific formation. I think it is safe to say that any successful EMdrive is going to be high-Q, and therefore require superconductors, which means cold or colder temperatures need to be maintained on operating drives. Such temperatures are not compatible with a compartment heated for human habitation, and not compatible with being exposed to sources of high radiation. The 'sunny side' may change due to the spacecraft's orientation, requiring certain emdrives on the sunny side to be powered off, while the 'shadow side' drives would be powered. The other drive location considerations are: distance from electrical source, proper fit to superstructure, and accessibility for diagnostics/replacement/repair.

It may be difficult to picture this configuration, after all of the pictures we have in our minds from 'rocketships'. Consider no central point of thrust generation, but instead, emdrive modules tucked away in various places throughout the spacecraft. I picture hundreds to thousands of such modules, each being a standardized affair which can be taken out of service for repair or replacement without considerable effect on the total thrust of the spacecraft. Distributed EMdrives would also encourage separate electrical sources, which may also be modular, probably to a lesser degree, perhaps with various types to allow the use of differing types of fuel and technology (nuclear fission and fusion of several types, antimatter, coal [J/K]).

However, my implementation scheme has little to do with actual testing. In the case of terrestrial testing, it does seem likely that there will be single devices tested, and not an array. However, the test-stand might be standardized to quickly allow the substitution of one type of EMdrive for another, making it easier to both empirically find higher-performance units, as well as to run experiments to come towards theoretical understanding.

Offline Augmentor

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 (lots cut for the sake of brevity )

Just one MORE fun challenge I would add - since we don't know what the  underlying theory of EMdrive is(assuming there is one) we can't assume effects are additive at all or how they will sum.   Generally arrays of antennas or other RF systems must be modeled and tuned carefully as there ARE interactions between individual components, not to mention support structure etc.   Those can be modeled and simulated (e.g. a vertical stack of yagi's or a beam forming array for a electrically steerable radar) BECAUSE we understand (at least pretty well heh heh ) how they work.   

That's possible, but not likely, by my reckoning. An EMDrive would have to convert all of its EMfields to thrust in order to be efficient. Any leakage would appear as heat.

Now, personally, I strongly SUSPECT that, if EMDrive is real and produces thrust, then any practical application likely WILL be an array of 'thrusters', particularly if used as primary delta V source - although  steering/stationkeeping might be able to be accomplished with practically realizable single thrusters (again assuming there ARE such things as practically realizable thrusters).

N. B.  This suspicion  is a completely NON Scientific viewpoint based on work experience - i.e. it is a GUESS with some history behind it a.k.a. "engineering judgment" . . . so take it with a supersized grain of doubt. 

When you say "array", consider that such an array would be 3D. Without specific inter-EM drive interaction, then EMdrives could be placed outside of a specific formation. I think it is safe to say that any successful EMdrive is going to be high-Q, and therefore require superconductors, which means cold or colder temperatures need to be maintained on operating drives. Such temperatures are not compatible with a compartment heated for human habitation, and not compatible with being exposed to sources of high radiation. The 'sunny side' may change due to the spacecraft's orientation, requiring certain emdrives on the sunny side to be powered off, while the 'shadow side' drives would be powered. The other drive location considerations are: distance from electrical source, proper fit to superstructure, and accessibility for diagnostics/replacement/repair.

It may be difficult to picture this configuration, after all of the pictures we have in our minds from 'rocketships'. Consider no central point of thrust generation, but instead, emdrive modules tucked away in various places throughout the spacecraft. I picture hundreds to thousands of such modules, each being a standardized affair which can be taken out of service for repair or replacement without considerable effect on the total thrust of the spacecraft. Distributed EMdrives would also encourage separate electrical sources, which may also be modular, probably to a lesser degree, perhaps with various types to allow the use of differing types of fuel and technology (nuclear fission and fusion of several types, antimatter, coal [J/K]).

However, my implementation scheme has little to do with actual testing. In the case of terrestrial testing, it does seem likely that there will be single devices tested, and not an array. However, the test-stand might be standardized to quickly allow the substitution of one type of EMdrive for another, making it easier to both empirically find higher-performance units, as well as to run experiments to come towards theoretical understanding.

If any space drive produces momentum change internally, and does not interfere externally with the local spacetime, particles or fields...or other space drive units, then close packed 3D arrays are a possibility. On the way to 3D arrays, the precursor will be 2.5 D arrays where 2D boards of thrusters are a planar array, and when the boards are stacked as in rack or backplane box, a Box of Boards (BOB) array allows easy physical access any unit in the array for installation and replacement.

However, if you look closely at some space designs, the MEGA for example, the piezo material is crystalline array in a disc or square format a 3D dimensional array ( molecular level 3D) , and multiple discs are used to create a stack array (disc level 1D linear array). So a MEGA unit already is a nested array structure.

A physical array of MEGA units on a board is yet another level (1D unit level, 2D array). BOBs are a 2.5D board array, and MBOBs are multiple BOB arrays ( boxes array 1D, 2D or 3D.)

With an emDrive, the elementary/atomic/molecular level is a 3D amorphous array of energy and particles in a box. MBOBs - multiple emDrive boxes - are possible in 1D-stack, 2D-planar, and 3D cubic.

Array can also be circular or spherical. Elements can be on a square grid,  rectangular grid, a radial grid or a concentric ring grid. Other geometries are possible as well.

In any space drive unit or array, navigating the craft under main power is made easier and faster by symmetric placement of the units with respect to the centerline of mass and the thrust vector sum.   


Offline dustinthewind

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Does this actually mean anything in suggesting some form of induced momentum via copper oxide?
https://scholar.google.com/scholar?cluster=3092911990202711870&hl=en&as_sdt=0,26
Exciton-phonon interaction breaking all antiunitary symmetries in external magnetic fields
Frank Schweiner, Patric Rommel, Jörg Main, Günter Wunner
Quote
We have shown analytically that the combined presence
of the cubic valence band structure and external
fields breaks all antiunitary symmetries for excitons in
Cu2O. When neglecting the exciton-phonon interaction,
this symmetry breaking appears only if the plane spanned
by the external fields is not identical to one of the symmetry
planes of the cubic lattice of Cu2O. We have discussed
that for these cases the additional presence of the
exciton-phonon interaction is not able to restore the broken
symmetries.
For the specific orientations of the external fields,
where the plane spanned by the fields is identical to one
of the symmetry planes of the cubic lattice, the excitonphonon
interaction becomes important. This interaction
causes a finite momentum of the exciton center of mass,
which leads to the motional Stark effect in an external
10
magnetic field.
If the cubic valence band structure is
considered, the effective electric field connected with the
motional Stark effect finally leads to the breaking of all
antiunitary symmetries. Since the exciton-phonon interaction
is always present in the solid, we have thus shown
that GUE statistics will be observable in all spectra of
magnetoexcitons irrespective of the orientation of the external
magnetic field, which is in agreement with the experimental
observations in Refs.

Offline Augmentor

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If any space drive produces momentum change internally, and does not interfere externally with the local spacetime, particles or fields...or other space drive units, then close packed 3D arrays are a possibility. On the way to 3D arrays, the precursor will be 2.5 D arrays where 2D boards of thrusters are a planar array, and when the boards are stacked as in rack or backplane box, a Box of Boards (BOB) array allows easy physical access any unit in the array for installation and replacement.

However, if you look closely at some space designs, the MEGA for example, the piezo material is crystalline array in a disc or square format a 3D dimensional array ( molecular level 3D) , and multiple discs are used to create a stack array (disc level 1D linear array). So a MEGA unit already is a nested array structure.

A physical array of MEGA units on a board is yet another level (1D unit level, 2D array). BOBs are a 2.5D board array, and MBOBs are multiple BOB arrays ( boxes array 1D, 2D or 3D.)

With an emDrive, the elementary/atomic/molecular level is a 3D amorphous array of energy and particles in a box. MBOBs - multiple emDrive boxes - are possible in 1D-stack, 2D-planar, and 3D cubic.

Array can also be circular or spherical. Elements can be on a square grid,  rectangular grid, a radial grid or a concentric ring grid. Other geometries are possible as well.

In any space drive unit or array, navigating the craft under main power is made easier and faster by symmetric placement of the units with respect to the centerline of mass and the thrust vector sum.   

In the case of any complex system such as a space-drive thruster, every level requires integration and test by integrating the parts and synthesizing the tangible physical parts with the power flow and fields.

From a single unit thrust to an array of thrusters on a board to multiple boxes of thrusters in a system, in such complex systems performing different functions, there is not just bench and lab testing, there is an independent prototype specification test as well as environmental testing - shake and bake. EMC testing including emissions and susceptibility is also performed at each levels.

If a problem is left to fester in design, build, integration, test or manufacturing, then she combination of customer and field support will need to involve engineering - hardware, software, signal and control - an issue in a complex system that requires a systems engineer to drive a solution gracefully.
 
Together, manufacturing gears up with engineering and support for alpha, beta and product release.Then there is alpha testing - innovators or first adopters - at a client's facility or field location with deep support of highly capable people and facilities. Beta test is an expansion to more clients who are first adopters.

For arrays of units, each unit has to be tested, and then there are integration tests at the array level both of line replaceable units - boards in a BOB - as well as at the BOB level.

So, spacedrive arrays such as MEGA or emDrive include four levels: unit, board, box and network. Scaling and throttling needs to be controlled at each level in amplification, active units at the board and box level, and total number of units in the network.

In a spacedrive system, beyond amplification and multiplication in order to meet throttling  and acceleration specifications,  the thrust to power ratio in Newtons per kWe is key consideration. N/kWe defines the power conversion for Newtons thrust output to power input.

Arrays will be controlled using fly-by-wire, fly-by-fiber, and fly-by-remote. Also, autonomous and AI controlled flying replaces the human with a computer using local computing power and programming such as general or dedicated processors , gate arrays, digital signal or even AI processors.

In any space drive, spaceship or spaceplatform, in order to support a variety of systems and missions, a combination of units, arrays and networks will be required, both individually and collectively.


Offline Bob Woods

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If any space drive produces momentum change internally, and does not interfere externally with the local spacetime, particles or fields...or other space drive units, then close packed 3D arrays are a possibility. On the way to 3D arrays, the precursor will be 2.5 D arrays where 2D boards of thrusters are a planar array, and when the boards are stacked as in rack or backplane box, a Box of Boards (BOB) array allows easy physical access any unit in the array for installation and replacement.

I just want to be noted that I am FIRMLY behind a multi-thruster unit that can power an interstellar craft to be called a BOB Drive!!!!

It just seems so, logical...  ;)
« Last Edit: 01/12/2018 04:43 AM by Bob Woods »

Offline graybeardsyseng

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If any space drive produces momentum change internally, and does not interfere externally with the local spacetime, particles or fields...or other space drive units, then close packed 3D arrays are a possibility. On the way to 3D arrays, the precursor will be 2.5 D arrays where 2D boards of thrusters are a planar array, and when the boards are stacked as in rack or backplane box, a Box of Boards (BOB) array allows easy physical access any unit in the array for installation and replacement.

I just want to be noted that I am FIRMLY behind a multi-thruster unit that can power an interstellar craft to be called a BOB Drive!!!!

It just seems so, logical...  ;)
Ahead BOB factor 5, Engage.

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

Offline graybeardsyseng

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 (lots cut for the sake of brevity )

Just one MORE fun challenge I would add - since we don't know what the  underlying theory of EMdrive is(assuming there is one) we can't assume effects are additive at all or how they will sum.   Generally arrays of antennas or other RF systems must be modeled and tuned carefully as there ARE interactions between individual components, not to mention support structure etc.   Those can be modeled and simulated (e.g. a vertical stack of yagi's or a beam forming array for a electrically steerable radar) BECAUSE we understand (at least pretty well heh heh ) how they work.   

That's possible, but not likely, by my reckoning. An EMDrive would have to convert all of its EMfields to thrust in order to be efficient. Any leakage would appear as heat.

Now, personally, I strongly SUSPECT that, if EMDrive is real and produces thrust, then any practical application likely WILL be an array of 'thrusters', particularly if used as primary delta V source - although  steering/stationkeeping might be able to be accomplished with practically realizable single thrusters (again assuming there ARE such things as practically realizable thrusters).

N. B.  This suspicion  is a completely NON Scientific viewpoint based on work experience - i.e. it is a GUESS with some history behind it a.k.a. "engineering judgment" . . . so take it with a supersized grain of doubt. 

When you say "array", consider that such an array would be 3D. Without specific inter-EM drive interaction, then EMdrives could be placed outside of a specific formation. I think it is safe to say that any successful EMdrive is going to be high-Q, and therefore require superconductors, which means cold or colder temperatures need to be maintained on operating drives. Such temperatures are not compatible with a compartment heated for human habitation, and not compatible with being exposed to sources of high radiation. The 'sunny side' may change due to the spacecraft's orientation, requiring certain emdrives on the sunny side to be powered off, while the 'shadow side' drives would be powered. The other drive location considerations are: distance from electrical source, proper fit to superstructure, and accessibility for diagnostics/replacement/repair.

It may be difficult to picture this configuration, after all of the pictures we have in our minds from 'rocketships'. Consider no central point of thrust generation, but instead, emdrive modules tucked away in various places throughout the spacecraft. I picture hundreds to thousands of such modules, each being a standardized affair which can be taken out of service for repair or replacement without considerable effect on the total thrust of the spacecraft. Distributed EMdrives would also encourage separate electrical sources, which may also be modular, probably to a lesser degree, perhaps with various types to allow the use of differing types of fuel and technology (nuclear fission and fusion of several types, antimatter, coal [J/K]).

However, my implementation scheme has little to do with actual testing. In the case of terrestrial testing, it does seem likely that there will be single devices tested, and not an array. However, the test-stand might be standardized to quickly allow the substitution of one type of EMdrive for another, making it easier to both empirically find higher-performance units, as well as to run experiments to come towards theoretical understanding.

Very thought provoking!   

First I completely agree that such arrays will be 3D assemblages of standardized, easily maintained/replaced units with distributed power, control and support infrastructure.  This brings to mind the similarity to RF beam forming networks such that the thrust vector would be controllable and steerable.  Very nice.

But I am a bit less sanguine that an a practical EMDrive would only  have 'leakage' as heat.   In building complex 3D arrays we will need to fully understand potential and actual interactions.   I mentioned RF interaction originally but other interaction might occur.

 Always with the caveat of "If there is an EMdrive effect".   

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

Offline Augmentor

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If the emDrive turns out to be nothing more than a fancy user of heat from a microwave, then the emDrive simply needs to become a heat pump that produces momentum change.

Online RotoSequence

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https://www.nature.com/articles/nphys4303

This stuff about polaritons and anomalous behaviors if polaritons and resonant cavities have the same frequency has me wondering if we're looking for an excitation state in the surface of copper-oxides.

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