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#3080 by Gilbertdrive on 22 Nov, 2016 07:38
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That is not because you think that other people claims are not accurate, that you can attribute them different claims.Bob012345, you simplify the claims of the people who disagree with you. The claim is that energy conservation is fundamentally violated if the emdrives doesn't steal energy to something else. You can not remove that if, that was already repeated many times, from the claim.
I think this is still not accurate. Kinetic energy is a special type of energy which is associated with motion and is dependent on the reference frame. When people talk about conversion of other (frame-independent) types of energy into kinetic energy, special care must be taken to make sure this conversion satisfies CoE in every inertial frame. If an object gains kinetic energy without pushing against something, it violates CoE (since kinetic energy gain will be frame dependent, while the expended potential energy is not). If it is pushing against something (but not carrying this "something" with it, like a conventional rocket), it will have to spend more and more energy per unit of time as its velocity relative to that "something" increases, since the potential energy will be spent for accelerating both objects in the opposite directions, which requires an increasing amount of energy due to the v^2 term (m(v + dv)^2/2 - mv^2/2 = mdv^2 / 2 + mdv, which is obviously greater than mdv^2/2). -
#3081 by TheTraveller on 22 Nov, 2016 07:57
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Lest we forget EmDrive history:
2002: 18.8mN/kW, SPR
2006: 287mN/kW, SPR
2009: 326mN/kW, SPR
2015: 1.2 - 21.3mN/kW, NASA
The 2009 data is for the 3.85Ghz Flight Thruster.
As Qu increases as the cavity gets bigger and cavity Rs drops as freq drops, going from a 3.85Ghz TE013 cavity to a 2.45GHz TE013 cavity should increase specific force to around 500mN/kW at room temp.
At 2.45Ghz Cu has a room temp Rs of around 8,000uOhm, Dropping the Cu temp to 77K (LN2) drops the Rs to around 15uOhms as per attached.
As cavity Q scales linear with Rs, the Cu room temp 88K Q at 2.45GHz should increase to a Q of 4.7x10^7 at 77K. https://en.wikipedia.org/wiki/Superconducting_radio_frequency#Physics_of_SRF_cavities
If the EmDrive's specific force does scale linear with Q, then the room temp predicted force of 0.5N/kW could increase up to 267N/kW. If so that is in levitator range as 27kg/kW is in a very interesting force range.
Should be a very interesting experiment.
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#3082 by Gilbertdrive on 22 Nov, 2016 09:02
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The discussions of spaceflight to near stars has focused on the power requirements to effect such a flight. These discussions have focused on nuclear fission reactors. Since this group has been on the bleeding edge of scientific controversy for so long and now seen confirmation of the effect I'd like to suggest that the power source for these flights may well turn out to be the Low Energy Nuclear Reaction otherwise disparagingly known as cold fusion.
I think that is important that we don't debate about LENR here (it is off topic) but we can use in our calculus LENR data, since the result is the same than with RTG or nuclear reactor.
That field has faced many of the same scientific prejudices and disdain that the EW drive has faced. It also has a dedicated cadre of DYI experimenters that have had many failures and occasional successes. Also like what has recently happened with the EW research there has been reputable research and successes by government agencies, in particular SPAWARS of the USN.
Just as the EW results have suggested that there is a new potential propulsion system, I suggest that the LENR results suggest that there is a potential new energy source that combined with the EM drive could be more than a little revolutionary.
Can you please indicate the state of the art LENR data in W/kg and total J/kg for use in space ? -
#3083 by Flyby on 22 Nov, 2016 09:26
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...
If the EmDrive's specific force does scale linear with Q, then the room temp predicted force of 0.5N/kW could increase up to 267N/kW. If so that is in levitator range as 27kg/kW is in a very interesting force range.
Should be a very interesting experiment.
TT, The whole question is the "IF"...
In all honesty, I know of no real world processes that scale in a linear way, over such a long stretch (going from Q 10^5 to Q 10^10), certainly not when thermodynamics are part of the process...
Oh btw, I do not always share your relentless optimism, but that doesn't mean we re not on the same boat, so to say...
As Paul March already indicated , there are a number of parameters that come in play, all interacting with each other, certainly when you focus on performance. Some of these parameters are opponents, like momentum transfer and high Q.
For me it is clear the the mean difficulty of building an EMdrive (or even establishing that the effect is real) lays in the very fact it is a "complex system"
https://en.wikipedia.org/wiki/Complex_system
If you look at the characteristics of complex systems you'll see that many of those have been brought up on this forum.
fe. Remember the "robustness" demonstrated by monomorphic when he changed the surface quality? I was amazed how stable the resonance patterns stayed , regardless the bumpy surface.
There is very little that is really linear or straight forward in regard of the EMdrive, hence the difficulty to grasp what is really happening, why it is happening and how to make it behave in a consistent matter.
This could also explain Shawyer's low development rate and also some of the strange EW results of having better performances at lower input power.
The great thing of this forum is the multi-discipline approach, with so many people with all different backgrounds and insights, each bringing in a small part of this fantastic puzzle. Eventually, a notion of what is going on will start to shape up. but it is a search into many possible roads, with lots of dead ends...
But hey... that's what makes it such a fun thing to watch unfold , and yes...even participate in... -
#3084 by Gilbertdrive on 22 Nov, 2016 09:56
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Bob012345, you simplify the claims of the people who disagree with you. The claim is that energy conservation is fundamentally violated if the emdrives doesn't steal energy to something else. You can not remove that if, that was already repeated many times, from the claim.
I think this is still not accurate. Kinetic energy is a special type of energy which is associated with motion and is dependent on the reference frame. When people talk about conversion of other (frame-independent) types of energy into kinetic energy, special care must be taken to make sure this conversion satisfies CoE in every inertial frame. If an object gains kinetic energy without pushing against something, it violates CoE (since kinetic energy gain will be frame dependent, while the expended potential energy is not). If it is pushing against something (but not carrying this "something" with it, like a conventional rocket), it will have to spend more and more energy per unit of time as its velocity relative to that "something" increases, since the potential energy will be spent for accelerating both objects in the opposite directions, which requires an increasing amount of energy due to the v^2 term (m(v + dv)^2/2 - mv^2/2 = mdv^2 / 2 + mdv, which is obviously greater than mdv^2/2).
I agree, but I am don't see the contradiction with my summary claim : The claim is that energy conservation is fundamentally violated if the emdrives doesn't steal energy to something else (in the context of a constant thrust greater than photon rocket for constant imput power)
Can you help me and reformulate this sentence ?
The aim isn't to have a sentence that give the complete story, but just to make it compatible with the CoE claims that some develop on this topic (You, Meberbs, I, etc...) The Bob sentence that I completed by an if seems to me now compatible with these claims (Of course it doesn't tell everything)This type of interaction should be similar to space probes using gravity assist interactions going around another planet to get an extra kinetic energy boost to their next destination by infinitesimally slowing the planet's or moon's orbital velocity they are passing. In the cosmological gravitational field case, the required slowing would IMO most likely end up being a reduction in the cosmological microwave background temperature.
That is a very interesting answer ! It is a way of satisfying CoE.
That is what I ask for any theory explaining the Emdrive. When the Emdrive gets Kinetic Energy from the universe (in any given inertial reference frame) what happen to the rest of the universe ? -
#3085 by TheTraveller on 22 Nov, 2016 10:43
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...
If the EmDrive's specific force does scale linear with Q, then the room temp predicted force of 0.5N/kW could increase up to 267N/kW. If so that is in levitator range as 27kg/kW is in a very interesting force range.
Should be a very interesting experiment.
TT, The whole question is the "IF"...
In all honesty, I know of no real world processes that scale in a linear way, over such a long stretch (going from Q 10^5 to Q 10^10), certainly not when thermodynamics are part of the process...
Oh btw, I do not always share your relentless optimism, but that doesn't mean we re not on the same boat, so to say...
As Paul March already indicated , there are a number of parameters that come in play, all interacting with each other, certainly when you focus on performance. Some of these parameters are opponents, like momentum transfer and high Q.
For me it is clear the the mean difficulty of building an EMdrive (or even establishing that the effect is real) lays in the very fact it is a "complex system"
https://en.wikipedia.org/wiki/Complex_system
If you look at the characteristics of complex systems you'll see that many of those have been brought up on this forum.
fe. Remember the "robustness" demonstrated by monomorphic when he changed the surface quality? I was amazed how stable the resonance patterns stayed , regardless the bumpy surface.
There is very little that is really linear or straight forward in regard of the EMdrive, hence the difficulty to grasp what is really happening, why it is happening and how to make it behave in a consistent matter.
This could also explain Shawyer's low development rate and also some of the strange EW results of having better performances at lower input power.
The great thing of this forum is the multi-discipline approach, with so many people with all different backgrounds and insights, each bringing in a small part of this fantastic puzzle. Eventually, a notion of what is going on will start to shape up. but it is a search into many possible roads, with lots of dead ends...
But hey... that's what makes it such a fun thing to watch unfold , and yes...even participate in...
I do understand complex systems and I also understand the basic physics that makes the "Shawyer Effect" generate force, at least to the level that following theory results in EmDrives that generate close to the predicted force.
What we do know from superconductive cavity theory is the Q should scale linear with Rs. Plus Rs scales with F and temp. Of course E & H field intensity also come into play and for sure achieving very high Q means being able to deal with very high stored energy and very high E & H fields.
I also know that dealing with YBCO is not easy and getting acceptable Rs at the Freq, Temp and H field intensity is a tricky game. Which is why Roger developed the latest EmDrive, which uses a flat YBCO thin film and a frustum with very steep side walls so the peak E & H fields are at the narrow end and away from the big end.
My game plan is to explore using a highly accurate, totally machined S band frustum +-20um and to do the necessary engineering to submerge the entire frustum in LN2.
While YBCO shows a possible pathway to a much lower Rs than can be obtained with LN2 cooled Cu, it will still be an interesting exercise to map the frustum Q and resonance changes at room temp and at 77K. Then to vary the power from 10mW to 250W and observe force generation changes at room temp vs 77K.
I believe doing this experiment with a Cu coated Al frustum will be a much easier and simpler exercise than adding in other new and unknown dimension by using YBCO. So for sure using YBCO may offer higher force generation but for now I plan to stick to something a lot easier and with less unknowns.
I have 5 frustums of various builds and designs, plus multiple 100W & 250W Rf amps arriving mid Dec. Have promised my wife to attend to a current health issue and enjoy Christmas and New Years with family and friends. So expect to re engage my experimental EmDrive research program sometime in Jan 2017.
BTW a little bread crumb:
Simple way to measure cavity Qu is to apply an Rf pulse, measure the rise time of forward power, take 20% of the 5x TC time as 1 Tc time and then calc the cavity Q using
Qu = Tc 2 Pi Freq
which can be done on every power pulse and allows dynamic Q changes to be measured and recorded.
So will be interesting to record dynamic Q changes as my frustums accelerate on the rotary test rig. Of course Roger's theory predicts the Q will drop as the EmDrive accelerates. The measure of the Q drop can then be used to calculate the energy loss from the cavity that is being used to cause acceleration.
So much information will come from such a simple to do measurement.
Should add that the Rs data I shared for the room temp and 77K Cu Rs plots are from real data measurements, so that helps to eliminate some of the complexity. -
#3086 by Rodal on 22 Nov, 2016 14:25
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...I do understand complex systems and I also understand the basic physics that makes the "Shawyer Effect" generate force, at least to the level that following theory results in EmDrives that generate close to the predicted force....
An empty closed copper cavity in the shape of a truncated cone and electromagnetically excited at a microwave frequency at kW or less power is now deemed to be a complex system?
Essential features of complex systems (as defined in mathematical physics https://en.wikipedia.org/wiki/Complex_system#Nonlinear_systems https://en.wikipedia.org/wiki/Complex_system#Chaotic_systems) are coupled dynamic nonlinear differential equations.
Yet, all the Finite Element (COMSOL, EMPro. etc.), Boundary Element Method (FEKO) and Finite Difference Method (Meep) analysis ever shown in all these 8 threads of the EM Drive, are based on solutions of linear differential equations. None of these analyses contain the coupled nonlinear differential equations features of a complex system So are all the papers of Shawyer. Furthermore, Shawyer himself has repeatedly said that all that is necessary to explain the EM Drive are Maxwell's equations (which are linear differential equations) and Newton's laws (also linear differential equations). The COMSOL, and FEKO analysis for mode shapes and frequencies match experimental results for frequency and mode shapes.
The statement that this is a complex system (as complex systems are defined) contradicts all the above, it even contradicts what Shawyer himself has published...it also contradicts the basis for all the analyses presented by Monomorphic and others (Monomorphic has used FEKO which solves linear differential equations, none of Monomorphic analyses have solved anything that can be defined as a complex system: no coupled dynamic nonlinear differential equations were solved).
The analysis presented by Zellerium at the top of this page: http://forum.nasaspaceflight.com/index.php?topic=40959.msg1612282#msg1612282 is also solving linear differential equations. Not meeting the definition of a complex system.
I am not aware or recall, anybody here ever even presenting coupled nonlinear differential equations for this problem, and much less attempting to solve them, even numerically !
Where is the evidence of strange attractors, or limit cycles, in the experimental data? On the contrary, just a few pages ago TT was showing a log-log plot over 6 orders of magnitude claiming simple behavior of thrust/InputPower versus Q
If a definition of complex system is being used that does not involve nonlinear dynamic coupled equations, it better be defined mathematically. For example complex systems often exhibit self‐organization, which happens when systems spontaneously order themselves (generally in an optimal or more stable way) without “external” tuning of a control parameter. This feature is not found in chaotic systems and is often called anti‐chaos. Again, where is the evidence for self-organization in the experimental data
Simple feedback or energy dissipation, by themselves, do not make a copper cavity a complex system... -
#3087 by Gilbertdrive on 22 Nov, 2016 14:56
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Will you share here photos and precise data of your next builds ? I think that we would all be very interested !
I have 5 frustums of various builds and designs, plus multiple 100W & 250W Rf amps arriving mid Dec. Have promised my wife to attend to a current health issue and enjoy Christmas and New Years with family and friends. So expect to re engage my experimental EmDrive research program sometime in Jan 2017.
I wish you a good recovery for your health problems. -
#3088 by giulioprisco on 22 Nov, 2016 15:09
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I wrote a popular article on the emerging EmDrive physical theory described in the EW paper. This is a short and hopefully readable outline of the developing theoretical model proposed by the NASA scientists. I think reversing the order of the considerations in the paper can make the outline easier to follow. Criticism welcome.
NASA Scientists Sketch Tentative Theory of EmDrive Propulsion
https://hacked.com/nasa-scientists-sketch-tentative-theory-emdrive-propulsion/ -
#3089 by rfmwguy on 22 Nov, 2016 16:44
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I wrote a popular article on the emerging EmDrive physical theory described in the EW paper. This is a short and hopefully readable outline of the developing theoretical model proposed by the NASA scientists. I think reversing the order of the considerations in the paper can make the outline easier to follow. Criticism welcome.
Nice article, thank you. Giving you some traffic from elsewhere in the emdrive universe
NASA Scientists Sketch Tentative Theory of EmDrive Propulsion
https://hacked.com/nasa-scientists-sketch-tentative-theory-emdrive-propulsion/ -
#3090 by TheTraveller on 22 Nov, 2016 16:47
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Simple feedback or energy dissipation, by themselves, do not make a copper cavity a complex system...
For me, as an engineer that builds EmDrives by applying Roger's theory equations, it is not complex at all. I understand the physics, as explained by Roger, and when applied to the real world, see it generate the predicted results.
As for Q * power scaling linear with force generation, that is just accelerator physics as is the relationship between Q and Rs and temp and freq. Of course in the real world not everything scales linear but as I see it, the vast majority of the effects do scale linear because if not there would not be accelerator cavities with Q 5x10^11.
So for sure it will not be a simple build to get a high performance room temp cavity to work well when immersed in LN2, but doing so it not something that has never been done before and thankfully Google is really good at digging out build data.
With a Cu 300K (room temp) Rs of around 8,000uOhm and a 77K Rs of around 15uOhm, there is more than ample margin to experimentally measure both the resultant Qu from doing forward power 1x Tc rise time calcs and doing force generation.
It then gets very exciting and interesting to do real time Q measurements with a non accelerating and accelerating thruster to see if the Q drops during acceleration and then to measure the energy representative of the Q drop which has exited the cavity and is doing work to accelerate the EmDrive.
That should be VERY interesting data as only a small increase in angular velocity on a rotary test rig should be sufficient to measure gained KE vs cavity energy drop from dropped Q.
More data will be added by reducing Rf amp power to become low enough to maintain constant velocity as against rotary test rig static and dynamic air resistance load and again record what happens to cavity Q as power is varied up and down around that constant velocity point.
Interesting times ahead. -
#3091 by WarpTech on 22 Nov, 2016 16:48
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I wrote a popular article on the emerging EmDrive physical theory described in the EW paper. This is a short and hopefully readable outline of the developing theoretical model proposed by the NASA scientists. I think reversing the order of the considerations in the paper can make the outline easier to follow. Criticism welcome.
NASA Scientists Sketch Tentative Theory of EmDrive Propulsion
https://hacked.com/nasa-scientists-sketch-tentative-theory-emdrive-propulsion/
Nice job, but Prof's Woodward and Fern just published an article in JBIS that refutes NASA's Quantum Vacuum conjecture. I would be interested in seeing Dr. White's rebuttal of that article. In the way the model is presented, I think Woodward and Fern are correct. However, there are other ways to use the QV to accomplish this that they do not mention, and that differs from Dr. White's approach. (AKA my approach to QG.)
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#3092 by WarpTech on 22 Nov, 2016 16:50
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Just out of curiosity, I started building the Cannae geometry based on their patent dimensions as attached and ran an Eigenmode sweep. Came up with the TM010 at 1.09 GHz which is pretty close to their resonant frequency of 1.047 GHz. I probably didn't make the grooves perfectly as I wasn't sure what the 1.513 dimension was referring to (bottom right corner of the attached picture).
The next mode is the TM110 around 1.7 GHz.
I wonder what balance between E field intensity and power gradient would yield optimal thrust...
What do the surface currents look like, slots vs no slots? -
#3093 by TheTraveller on 22 Nov, 2016 16:57
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I wrote a popular article on the emerging EmDrive physical theory described in the EW paper. This is a short and hopefully readable outline of the developing theoretical model proposed by the NASA scientists. I think reversing the order of the considerations in the paper can make the outline easier to follow. Criticism welcome.
NASA Scientists Sketch Tentative Theory of EmDrive Propulsion
https://hacked.com/nasa-scientists-sketch-tentative-theory-emdrive-propulsion/
One issue is NASA measured static force generation big to small with a dielectric at the small end and small to big when the dielectric was not used.
Roger Shawyer, in 2002 and in 2006 also measured static force being generated in non dielectric frustums small to big as attached.
Would like to see any of these theories explain the small to big non dielectric static force generation that has been measured by NASA and Roger.
For sure, any theory needs to be able to explain ALL the measured data.
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#3094 by TheTraveller on 22 Nov, 2016 17:04
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Will you share here photos and precise data of your next builds ? I think that we would all be very interested !
I have 5 frustums of various builds and designs, plus multiple 100W & 250W Rf amps arriving mid Dec. Have promised my wife to attend to a current health issue and enjoy Christmas and New Years with family and friends. So expect to re engage my experimental EmDrive research program sometime in Jan 2017.
I wish you a good recovery for your health problems.
That is the plan. Lots of data, picts and videos. I believe any EmDrive test data is way too important to not be made public.
With my 1st test run, the Rf amp's variable attenuator died shortly after I started my tests and I didn't get an chance to take a video. Was compounded in that it was lost in shipment after being repaired. This time I have 4 brand new Rf amps arriving mid Dec. 2 x 100W and 2 x 250W, so if anything goes bang again, it will not stop the test program. -
#3095 by Star-Drive on 22 Nov, 2016 17:05
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Just out of curiosity, I started building the Cannae geometry based on their patent dimensions as attached and ran an Eigenmode sweep. Came up with the TM010 at 1.09 GHz which is pretty close to their resonant frequency of 1.047 GHz. I probably didn't make the grooves perfectly as I wasn't sure what the 1.513 dimension was referring to (bottom right corner of the attached picture).
The next mode is the TM110 around 1.7 GHz.
I wonder what balance between E field intensity and power gradient would yield optimal thrust...
What do the surface currents look like, slots vs no slots?
Zellerium:
And what was the assumed ac resistivity of the niobium cavity and the RF input power that generated the calculated E-field values shown in your plots? -
#3096 by TheTraveller on 22 Nov, 2016 17:33
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Yeah, not looking good to me either. I don't see any model of how it "blurred the impulsive response of this test article in time", nor any empirical indication. What I see is that the response time for all of the calibration pulses is very consistently ~4 seconds at multiple positions of the pendulum, both before and after heating, including in the null test where the pendulum was still highly displaced by the thermal effects when they applied the second calibration pulse.
All:
This will be my last post of the day. The EW Integrated Copper Frustum Test Article (ICFTA) had metallic and plastic components with competing and non-linear thermal expansions and contractions when heated, see previous posted slides on this topic, that when driving the torque pendulum's center of gravity shifts, blurred the impulsive response of this test article in time, dependent on the magnitude of the impulsive force. For me, it is fully explained in the text of the JPP report, so please go back and read it this section again until it hopefully makes sense to you.
Best, Paul M.
JPP means the Journal of Propulsion and Power, right? I do not think the discussion is satisfactory. In particular, why does the measurement device respond so much faster to calibration impulses? And if there are significant non-linearities, how can you justify you measurement protocol, which (as far as I understand) _assumes_ linear superposition of thrust and thermal signal?
EW is not alone in observing there is a time for the force to build up.
Roger also observed it with both the Experimental and Demonstrator EmDrives as attached.
I believe it has to do with the operational best point of the EmDrive being slightly off and the EmDrive pulling the natural resonant freq to be a better match to that of the applied Rf.
Sort of how a slightly off freq magnetron will be pulled into a freq lock with a resonant load that has a higher Q than that of the magnetron even though the high Q load has a different resonant freq to the magnetron. Give them time and they will work it out and lock to each other.
May also be related to the force bandwidth being much narrower than the rtn loss bandwidth.
Point is that EmDrives do generate force but please do not think of that force as being like any force you have ever experienced before. It has very different characterists.
So YES EmDrives can SOMETIME be slow to generate their force as evident by both EW's data and by Roger's data. Here again EW confirm what Roger measured way back in 2002 and 2006.
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#3097 by OnlyMe on 22 Nov, 2016 17:36
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...I do understand complex systems and I also understand the basic physics that makes the "Shawyer Effect" generate force, at least to the level that following theory results in EmDrives that generate close to the predicted force....
An empty closed copper cavity in the shape of a truncated cone and electromagnetically excited at a microwave frequency at kW or less power is now deemed to be a complex system?
Essential features of complex systems (as defined in mathematical physics https://en.wikipedia.org/wiki/Complex_system#Nonlinear_systems https://en.wikipedia.org/wiki/Complex_system#Chaotic_systems) are coupled dynamic nonlinear differential equations.
Yet, all the Finite Element (COMSOL, EMPro. etc.), Boundary Element Method (FEKO) and Finite Difference Method (Meep) analysis ever shown in all these 8 threads of the EM Drive, are based on solutions of linear differential equations. None of these analyses contain the coupled nonlinear differential equations features of a complex system So are all the papers of Shawyer. Furthermore, Shawyer himself has repeatedly said that all that is necessary to explain the EM Drive are Maxwell's equations (which are linear differential equations) and Newton's laws (also linear differential equations). The COMSOL, and FEKO analysis for mode shapes and frequencies match experimental results for frequency and mode shapes.
The statement that this is a complex system (as complex systems are defined) contradicts all the above, it even contradicts what Shawyer himself has published...it also contradicts the basis for all the analyses presented by Monomorphic and others (Monomorphic has used FEKO which solves linear differential equations, none of Monomorphic analyses have solved anything that can be defined as a complex system: no coupled dynamic nonlinear differential equations were solved).
The analysis presented by Zellerium at the top of this page: http://forum.nasaspaceflight.com/index.php?topic=40959.msg1612282#msg1612282 is also solving linear differential equations. Not meeting the definition of a complex system.
I am not aware or recall, anybody here ever even presenting coupled nonlinear differential equations for this problem, and much less attempting to solve them, even numerically !
Where is the evidence of strange attractors, or limit cycles, in the experimental data? On the contrary, just a few pages ago TT was showing a log-log plot over 6 orders of magnitude claiming simple behavior of thrust/InputPower versus Q
If a definition of complex system is being used that does not involve nonlinear dynamic coupled equations, it better be defined mathematically. For example complex systems often exhibit self‐organization, which happens when systems spontaneously order themselves (generally in an optimal or more stable way) without “external” tuning of a control parameter. This feature is not found in chaotic systems and is often called anti‐chaos. Again, where is the evidence for self-organization in the experimental data
Simple feedback or energy dissipation, by themselves, do not make a copper cavity a complex system...
Dr. Rodal, to be fair I was impressed by the fact that TT had backed off of the direct promotion of Shawyer's theory in his last post... and since none of the mathematical models or any current theory successfully explains any underlying mechanism resulting in thrust, something more complex than expected must be going on.
I believe it unfair to insist on a ridged mathematical definition of words like "complex" when the discussion moves back and forth between mathematical models and practical engineering.
It is certain that there are significant inconsistencies in, at least how Shawyer's theory is communicated (being generous). But at the same time there is no current theory that completely explains the thrust, or fully explains any systemic or experimental error that leads to a measurement interpreted as thrust. -
#3098 by OnlyMe on 22 Nov, 2016 17:46
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Simple feedback or energy dissipation, by themselves, do not make a copper cavity a complex system...
For me, as an engineer that builds EmDrives by applying Roger's theory equations, it is not complex at all. I understand the physics, as explained by Roger, and when applied to the real world, see it generate the predicted results.
As for Q * power scaling linear with force generation, that is just accelerator physics as is the relationship between Q and Rs and temp and freq. Of course in the real world not everything scales linear but as I see it, the vast majority of the effects do scale linear because if not there would not be accelerator cavities with Q 5x10^11.
So for sure it will not be a simple build to get a high performance room temp cavity to work well when immersed in LN2, but doing so it not something that has never been done before and thankfully Google is really good at digging out build data.
With a Cu 300K (room temp) Rs of around 8,000uOhm and a 77K Rs of around 15uOhm, there is more than ample margin to experimentally measure both the resultant Qu from doing forward power 1x Tc rise time calcs and doing force generation.
It then gets very exciting and interesting to do real time Q measurements with a non accelerating and accelerating thruster to see if the Q drops during acceleration and then to measure the energy representative of the Q drop which has exited the cavity and is doing work to accelerate the EmDrive.
That should be VERY interesting data as only a small increase in angular velocity on a rotary test rig should be sufficient to measure gained KE vs cavity energy drop from dropped Q.
More data will be added by reducing Rf amp power to become low enough to maintain constant velocity as against rotary test rig static and dynamic air resistance load and again record what happens to cavity Q as power is varied up and down around that constant velocity point.
Interesting times ahead.
And then again...,
There is a difference between Shawyer's theory and the formulas he and it seems you use to describe and predict, the design and performance of an EmDrive. It has always seemed to me that Shawyer's evolution of the EmDrive has been based on an engineering based trial and error. Thus his math based formulas also seem closer to having been derived from the engineering experience.., trial and error...
Beyond that I remind you again that any attempt to use how the efficiency of particle accelerators scales is fatally flawed in that the EmDrives being publicly discussed operate at very different frequencies and incorporate very different technologies. That being the case a there is a far greater burden on you to explain just why what is seen in the case of an accelerator, might apply in the case of a copper box filled with microwaves.... -
#3099 by OnlyMe on 22 Nov, 2016 17:56
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I wrote a popular article on the emerging EmDrive physical theory described in the EW paper. This is a short and hopefully readable outline of the developing theoretical model proposed by the NASA scientists. I think reversing the order of the considerations in the paper can make the outline easier to follow. Criticism welcome.
NASA Scientists Sketch Tentative Theory of EmDrive Propulsion
https://hacked.com/nasa-scientists-sketch-tentative-theory-emdrive-propulsion/
One issue is NASA measured static force generation big to small with a dielectric at the small end and small to big when the dielectric was not used.
Roger Shawyer, in 2002 and in 2006 also measured static force being generated in non dielectric frustums small to big as attached.
Would like to see any of these theories explain the small to big non dielectric static force generation that has been measured by NASA and Roger.
For sure, any theory needs to be able to explain ALL the measured data.
Or the systemic and/or experimental error that lead to the data in question....
I harp on this because even though you continue to point to Shawyer's past claimed results, there is very little in the way of published design detail of either the frustums or experimental equipment and environment, he used.
It makes the claims sound a great deal more like hearsay, than the result of real experimental data... And I am not saying that there was not data, just that it does not seem to be available for critical examination.
