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#960 by TheTraveller on 25 Sep, 2016 11:49
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If you read my last paper, then you should understand that Gravity can be modeled as damping of the resonance, aka "resistance". As Q increases, so do the losses from resistance due to higher power and current, and the thrust increases accordingly. I suspect that the reason we haven't heard about the great performance of a superconducting frustum, is because when all the resistive losses are removed, so is the thrust. Shawyer is probably still trying to figure out why it doesn't work with 1000X more thrust than the non-superconducting drive.
Is that the start of technical insight from theoretical understanding that we are seeing here?
Seems like indeed a lot happened in that workshop, that we have yet to see surface.
Also, if I understand well what you are saying, a superconductive Emdrive is simply a wrong path. Only non superconductive ones would show any effect.
Which makes me wonder, how strong can it get? which are the critical parameters to optimize for seeing a clear signal from any experiment, according to this model?
If I could answer those questions I'd be famous. There seems to be a common theme pertaining to gravity, and damping as presented in my paper. My "prediction" is that the superconducting frustum won't work. DIY'ers might consider using other materials besides copper, such as brass or nickel, or asymmetrical metal end plates such as copper in the back and nickel in the front, and see how these compare to copper. I don't have any other insights at this time.
I would put this in a more uncertain terms.
In a superconducting cavity, the skin depth is not zero. In case of superconductor: skin depth δ must be replaced with London penetration depth (https://en.wikipedia.org/wiki/London_penetration_depth
https://en.wikipedia.org/wiki/London_equations). Also: https://en.wikipedia.org/wiki/Meissner_effect
Since the reason for superconductivity in a material is quite complex, naive extrapolations to the effectiveness of a superconducting EM Drive cannot and should not be based on just extrapolating results obtained from copper cavities based on "Q" quality factor scaling. (As some experimenters may have initially hoped)
Measured cyro cavity Qu is a real value. OK sure skin depth at cryo temps is complex for any cavity, even Cu or Ag and simplistic projections are not correct. However knowing the measured cavity cryo Qu does allow calculation of the energy storage of the cavity and from that thrust can be realistically calculated.
BTW when can we expect to see a MEGA thruster achieving 100mN of real world continual thrust for 24 hours? -
#961 by TheTraveller on 25 Sep, 2016 12:00
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The Traveller : It does not matter since in the accelerating referential of the ship the Kinetic Energy is always zero, so no problem.
If you were on the ship, I suggest you would appreciate ir's frame is the only frame that matters as the ship's EmDrive does work on the ship's mass to match velocity with a desired destination where you will disembark.
What some observer, on a different frame, calculates as KE change matters or effects the ship how? -
#962 by TheTraveller on 25 Sep, 2016 12:21
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At resonance the cavity would be purely resistive. The inductive reactance and capacitive reactance are conjugates. For maximum power to be coupled to the EM-Drive (ie: highest Q) the inductive reactance and capacitive reactance have to be complex conjugates. So to say an EM-Drive is a kind of capacitor does not make physical sense. That's just my opinion. I am interested to see how this idea is developed and how it causes the thrust claimed for EM-Drives.
Agree.
Engineering wise, the cavity functions as a resonant parallel LC circuit. Inductive like below resonance, capacitive like above resonance, resistive like at resonance, with time constant & fill / discharge time like any parallel resonant circuit.
This is not now a capacitor operates. -
#963 by SeeShells on 25 Sep, 2016 12:42
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I'm not sure how much to say as I'm expanding my building beyond this model and getting data.QuoteDr. Jean-Philippe Montillet of the École Polytechnique Fédérale de Lausanne, Switzerland, presented a paper titled "Model of the EM Drive with the EMG coupling"
. I'll be looking forward to reading the paper when I get back home to a proper computer. It was nearly impossible to hear him speak on skype.
I'm glad someone took my ramblings seriously on the evanescent wave functions and the blending of the Mach effect and other theories.
You all have a good weekend.
My Best,
Shell
And I'm glad Dr. Montillet kept working on a theroretical explanation of EmDrive thrust, we heard from him back to thread 6!
Dr. Montillet is brilliant, as are you, Rodal, Todd and the many others who are contributing... (If I listed you all here I'd fill out this page, but ve have vays to know vho you are (in a bad German accent))
. I'm just an old girl engineer that's trying to wrap my head around some of the maths. I'm indebted to you all.
OK... hot tub time, as I promised not to work this weekend.
My Best,
Shell
PS: Sections 4.2 and 4.3 are critical to understand in; Multiplicity of Solutions for Linear Partial Differential Equations Using (Generalized) Energy Operators
September 11, 2015
J.-P. Montillet
http://arxiv.org/pdf/1509.02603v1.pdf -
#964 by birchoff on 25 Sep, 2016 13:52
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P.S. I saw HMXHMX say the videographers have to do some editing. Honestly, given the nirvana I imagine going on at this conference I would rather watch those videos unedited.
Not really. There were many times when the room turned into a fur-ball of multiple conversations all at once. Interruptions, everyone running out to see a rainbow, projector issues, dinner plans, etc. These parts of the recording would be useless to everyone and would make the resulting video much longer than it needs to be. We were in there for 3 whole days, I'd estimate there are probably at least 24 hours of video and audio to sift though and piece together into a coherent presentation. It would be a waste of the viewers time to listen to that garble.
From the perspective of wanting maximum technical information with the least amount of distraction. I would agree with you. However, if the ideas we are talking about lead to humanity developing a device that allows them to interact with gravity in a manner previously not allowed. I don't think it hyperbole to believe this workshop will be an important foot note in history. So being able to hear the raw discussions without anyone's editing would be useful. -
#965 by rq3 on 25 Sep, 2016 14:13
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If you read my last paper, then you should understand that Gravity can be modeled as damping of the resonance, aka "resistance". As Q increases, so do the losses from resistance due to higher power and current, and the thrust increases accordingly. I suspect that the reason we haven't heard about the great performance of a superconducting frustum, is because when all the resistive losses are removed, so is the thrust. Shawyer is probably still trying to figure out why it doesn't work with 1000X more thrust than the non-superconducting drive.
Is that the start of technical insight from theoretical understanding that we are seeing here?
Seems like indeed a lot happened in that workshop, that we have yet to see surface.
Also, if I understand well what you are saying, a superconductive Emdrive is simply a wrong path. Only non superconductive ones would show any effect.
Which makes me wonder, how strong can it get? which are the critical parameters to optimize for seeing a clear signal from any experiment, according to this model?
If I could answer those questions I'd be famous. There seems to be a common theme pertaining to gravity, and damping as presented in my paper. My "prediction" is that the superconducting frustum won't work. DIY'ers might consider using other materials besides copper, such as brass or nickel, or asymmetrical metal end plates such as copper in the back and nickel in the front, and see how these compare to copper. I don't have any other insights at this time.
I would put this in a more uncertain terms.
In a superconducting cavity, the skin depth is not zero. In case of superconductor: skin depth δ must be replaced with London penetration depth (https://en.wikipedia.org/wiki/London_penetration_depth
https://en.wikipedia.org/wiki/London_equations). Also: https://en.wikipedia.org/wiki/Meissner_effect
Since the reason for superconductivity in a material is quite complex, naive extrapolations to the effectiveness of a superconducting EM Drive cannot and should not be based on just extrapolating results obtained from copper cavities based on "Q" quality factor scaling. (As some experimenters may have initially hoped)
It would be interesting if the big end were superconducting and the rest was not.
It would also be interesting if the impedance of the skin effect were matched to the input impedance of the cavity. -
#966 by Rodal on 25 Sep, 2016 14:26
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...To come back to your message, Dr Rodal, if the frustrum is explained as a capacitor, does it mean that the thrust could be a Biefeld-Brown effect ? It would be very sad.
If you are referring to Dr. Montillet's paper, as explained in this message ( https://forum.nasaspaceflight.com/index.php?topic=40959.msg1588214#msg1588214 ), "Montillet only discusses equivalent circuit models to facilitate understanding of the differential equations involved. Of course, since Montillet's discussion involves evanescent waves, Montillet treatment in his paper is mathematical and not based on equivalent circuits". The force of the EM Drive is explained by Montillet as a gravitational Mach/Sciama/Woodward effect. -
#967 by meberbs on 25 Sep, 2016 14:35
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First, the ship frame is not an inertial frame. You can't simply apply conservation of energy, or really do energy based calculations in that frame without taking the acceleration into account. There would be a "fictitious" work terms that need to be integrated into the energy calculation to get the right answer, just like you have to account for the "fictitious" centrifugal and Coriolis forces in a rotating reference frame. (fictitious is an unfortunate word, since the forces are quite real)The Traveller : It does not matter since in the accelerating referential of the ship the Kinetic Energy is always zero, so no problem.
If you were on the ship, I suggest you would appreciate ir's frame is the only frame that matters as the ship's EmDrive does work on the ship's mass to match velocity with a desired destination where you will disembark.
What some observer, on a different frame, calculates as KE change matters or effects the ship how?
Second, physics is immune to changes in reference frame (although additional details are needed to be included for non-inertial frames) If you show CoE broken in one frame then it is broken. Pick any (for simplicity preferably inertial) frame and you should be able to calculate where the device will end up. This should be the same result no matter what frame you do it in. -
#968 by RotoSequence on 25 Sep, 2016 14:45
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At resonance the cavity would be purely resistive. The inductive reactance and capacitive reactance are conjugates. For maximum power to be coupled to the EM-Drive (ie: highest Q) the inductive reactance and capacitive reactance have to be complex conjugates. So to say an EM-Drive is a kind of capacitor does not make physical sense. That's just my opinion. I am interested to see how this idea is developed and how it causes the thrust claimed for EM-Drives.
Agree.
Engineering wise, the cavity functions as a resonant parallel LC circuit. Inductive like below resonance, capacitive like above resonance, resistive like at resonance, with time constant & fill / discharge time like any parallel resonant circuit.
This is not now a capacitor operates.
If the capacitor analogy is better than a very loose one, I'd suspect an EM drive stores a rather different form of energy than electric charge. -
#969 by BeamRider on 25 Sep, 2016 16:03
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I have a question concerning the statement that if you were inside an accelerating rocket, with no external view or information, that it is impossible to distinguish between the force of acceleration and gravity, such as might be experienced if the rocket was standing on the surface of a planet. My question is why cannot the gradient of gravitational attraction found near a planet (say) be used to distinguish between gravity and acceleration?
That is, would not a gravitometer in the top of the rocket compartment measure less force than one at the base, and would those devices not measure exactly the same force under a constant acceleration?
Of course the gravity gradient would be very small and perhaps even impossible to measure, although I do recall reading of a measurement of a gradient using a tall building, so it is apparently measureable at some level. But the statement of principle attributed to Einstein (?) does not say "almost impossible" - it says impossible, period. Since this principle seems central to understanding the EM arguments pro and con, I wonder if anyone here can help me understand the flaw in my thinking? -
#970 by Rodal on 25 Sep, 2016 16:11
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I have a question concerning the statement that if you were inside an accelerating rocket, with no external view or information, that it is impossible to distinguish between the force of acceleration and gravity, such as might be experienced if the rocket was standing on the surface of a planet. My question is why cannot the gradient of gravitational attraction found near a planet (say) be used to distinguish between gravity and acceleration?
See: http://physics.stackexchange.com/questions/172739/is-the-lay-explanation-of-the-equivalence-principle-wrong
That is, would not a gravitometer in the top of the rocket compartment measure less force than one at the base, and would those devices not measure exactly the same force under a constant acceleration?
Of course the gravity gradient would be very small and perhaps even impossible to measure, although I do recall reading of a measurement of a gradient using a tall building, so it is apparently measureable at some level. But the statement of principle attributed to Einstein (?) does not say "almost impossible" - it says impossible, period. Since this principle seems central to understanding the EM arguments pro and con, I wonder if anyone here can help me understand the flaw in my thinking?
http://www.umich.edu/~mctp/SciPrgPgs/events/2008/SS08/EP_Mich.pdf -
#971 by meberbs on 25 Sep, 2016 16:19
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I have a question concerning the statement that if you were inside an accelerating rocket, with no external view or information, that it is impossible to distinguish between the force of acceleration and gravity, such as might be experienced if the rocket was standing on the surface of a planet. My question is why cannot the gradient of gravitational attraction found near a planet (say) be used to distinguish between gravity and acceleration?
The impossible to tell the difference is between an acceleration and a uniform gravitational field. As you pointed out, a planet doesn't have a uniform field, and that could be detected. I believe an infinite flat plane of uniform density would produce a truly uniform gravitational field, if you want an example of how that could theoretically exist.
That is, would not a gravitometer in the top of the rocket compartment measure less force than one at the base, and would those devices not measure exactly the same force under a constant acceleration?
Of course the gravity gradient would be very small and perhaps even impossible to measure, although I do recall reading of a measurement of a gradient using a tall building, so it is apparently measureable at some level. But the statement of principle attributed to Einstein (?) does not say "almost impossible" - it says impossible, period. Since this principle seems central to understanding the EM arguments pro and con, I wonder if anyone here can help me understand the flaw in my thinking?
Also, while it was brought up by someone, none of the points I have made rely on the gravity/acceleration equivalence. Just the fact that non-inertial frames aren't the same as inertial frames which is from basic Newtonian physics, and all inertial reference frames are equivalent from special relativity. -
#972 by Rodal on 25 Sep, 2016 17:17
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You post this after this issue has already been explained in this post: https://forum.nasaspaceflight.com/index.php?topic=40959.msg1588214#msg1588214 , which the person you are addressing (zen-in) already gave a "like" to, and you ignore this explanation in your post. Again, Dr. Montlillet's paper is not about a capacitor. As explained, he initially uses an equivalent circuit model to motivate understanding of the differential equations in his formal paper. Also, at the workshop, rather than presenting the actual, full mathematical equations for the evanescent wave solution, and given the small amount of time given for his presentation, the foreign accent and quality of audio transmission, he wisely used his time to first show an equivalent circuit model that electrical engineers could easily relate to (rather than differential equations).At resonance the cavity would be purely resistive. The inductive reactance and capacitive reactance are conjugates. For maximum power to be coupled to the EM-Drive (ie: highest Q) the inductive reactance and capacitive reactance have to be complex conjugates. So to say an EM-Drive is a kind of capacitor does not make physical sense. That's just my opinion. I am interested to see how this idea is developed and how it causes the thrust claimed for EM-Drives.
Agree.
Engineering wise, the cavity functions as a resonant parallel LC circuit. Inductive like below resonance, capacitive like above resonance, resistive like at resonance, with time constant & fill / discharge time like any parallel resonant circuit.
This is not now a capacitor operates.
Furthermore, as SeeShells stated:....
QuoteDr. Jean-Philippe Montillet of the École Polytechnique Fédérale de Lausanne, Switzerland, presented a paper titled "Model of the EM Drive with the EMG coupling"
. I'll be looking forward to reading the paper when I get back home to a proper computer. It was nearly impossible to hear him speak on skype.
...
Given your response that instead takes the very first simplified analogy for the real thing, we might as well wait for all the videos of the presentations at the Estes Park Breaktrhough Propulsion Workshop to be posted at www.ssi.org and the papers of the conference to be released than to attempt to briefly discuss any other presentations.
Because obviously there is no space here to post the full paper, and one cannot post LaTeX equations here. And because a good-will attempt to try to use an analogy to briefly explain the mathematical solution in simple terms to a wider audience unfortunately resulted in some people confusing the simplified analogy with the actual model. -
#973 by Bob012345 on 25 Sep, 2016 18:00
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I will look for that talk when the video becomes available. However my first reaction to this idea that a cavity can act like a capaciter is to ask whoever makes that claim to look at the boundary conditions. The inside of the cavity is a conductor so any em field at that interface will have a high current, low voltage node. There are RF topologies that do act like capacitors. They are usually at the end of a 1/4λ driven conductor, typically an antenna, and sometimes have rounded flat surfaces. At resonance the cavity would be purely resistive. The inductive reactance and capacitive reactance are conjugates. For maximum power to be coupled to the EM-Drive (ie: highest Q) the inductive reactance and capacitive reactance have to be complex conjugates. So to say an EM-Drive is a kind of capacitor does not make physical sense. That's just my opinion. I am interested to see how this idea is developed and how it causes the thrust claimed for EM-Drives.
If you read my last paper, then you should understand that Gravity can be modeled as damping of the resonance, aka "resistance". As Q increases, so do the losses from resistance due to higher power and current, and the thrust increases accordingly. I suspect that the reason we haven't heard about the great performance of a superconducting frustum, is because when all the resistive losses are removed, so is the thrust. Shawyer is probably still trying to figure out why it doesn't work with 1000X more thrust than the non-superconducting drive.
https://www.researchgate.net/publication/305501551_AN_ENGINEERING_MODEL_OF_QUANTUM_GRAVITY
I wouldn't count Shawyer out just yet. I could just as well assume there is a lot of progress behind the scenes. Also, Cannae reports a fairly high superconducting thrust. -
#974 by Star One on 25 Sep, 2016 18:06
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This new paper seems relevant if the EM drive works the way Dr Rodal proposes.
How Isotropic is the Universe?QuoteA fundamental assumption in the standard model of cosmology is that the Universe is isotropic on large scales. Breaking this assumption leads to a set of solutions to Einstein’s field equations, known as Bianchi cosmologies, only a subset of which have ever been tested against data. For the first time, we consider all degrees of freedom in these solutions to conduct a general test of isotropy using cosmic microwave background temperature and polarization data from Planck. For the vector mode (associated with vorticity), we obtain a limit on the anisotropic expansion of (σV/H)0<4.7×10−11 (95% C.L.), which is an order of magnitude tighter than previous Planck results that used cosmic microwave background temperature only. We also place upper limits on other modes of anisotropic expansion, with the weakest limit arising from the regular tensor mode, (σT,reg/H)0<1.0×10−6 (95% C.L.). Including all degrees of freedom simultaneously for the first time, anisotropic expansion of the Universe is strongly disfavored, with odds of 121 000:1 against.
http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.117.131302 -
#975 by Rodal on 25 Sep, 2016 18:12
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This new paper seems relevant if the EM drive works the way Dr Rodal proposes.
Thank you, but if the EM Drive turns out to actually function as Dr. Montillet proposes, Dr. Montillet deserves the full and total credit for his explanation and derivation.
...
I will refrain from discussing any other presentations at the Estes Park Breakthrough Propulsion Workshop until the videos and presentations are made available at www.ssi.org -
#976 by Bob012345 on 25 Sep, 2016 18:15
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This rebuttal of the CoE over unity arguments seems pertinent: http://ssi.org/epi/Over-Unity_Argument_&_Mach_Effect_Thrusters.pdf
That is what I responded to a few posts back. The short version is that the paper is completely wrong.
Sorry, but Woodward's arguments are convincin. I think he knows what he's talking about esp. since he's been dealing with this for decades. -
#977 by Star One on 25 Sep, 2016 18:33
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This new paper seems relevant if the EM drive works the way Dr Rodal proposes.
Thank you, but if the EM Drive turns out to actually function as Dr. Montillet proposes, Dr. Montillet deserves the full and total credit for his explanation and derivation.
...
I will refrain from discussing any other presentations at the Estes Park Breakthrough Propulsion Workshop until the videos and presentations are made available at www.ssi.org
I apologise you're quite correct a poor choice of words on my behalf. -
#978 by Monomorphic on 25 Sep, 2016 18:51
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I've been working on spherical end-plate emdrive meshes that can be 3d printed or CNC machined. Not a lot of 3d printing shops can print something the size of the side walls in a ~2.4Ghz TE013 frustum, so for one option, I have split the side walls in two.
I can print the entire 3-piece frustum in ASA for $670. And then copper/silver electroplate the ASA. I still need to add bolt holes, but haven't decided on a bolt size yet.
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#979 by birchoff on 25 Sep, 2016 19:17
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The figure of merit itself is not a mistake, it's how people use it to prove a constant force basically does not cause a constant acceleration which is implicit in the criticisms.
If it is not a mistake then CoE is broken. Denying this is pointless.
I don't believe CoE or CoM will be violated by a proven theory. That extra energy/momentum is likely coming from a source we previously didn't think possible to tap. However, I do accept your point that as currently defined by Shawyer his theory would violate CoE/CoM. However, I don't remember who said this. But I am inclined to agree that the Theory Shawyer has floated is likely incomplete. Not sure if that is on purpose (For reasons Shawyer deems important) or just because he is still developing it.As I understand Woodward's comments, he's saying one can think of that supposed break even limit as an interval. After that interval, reset or re-guage the problem. Think of a rocket doing a long series of small burns. One ends up with a series of frames, in each energy was not violated but it's a simple undeniable fact of nature that the devices velocity in the last frame is the linear sum of all the frames yet the kinetic energy is different in each frame and far exceeds the sum of input energies in the last frame. But it's not a paradox at all. It's just how nature works and has always been built into classical mechanics. Woodward's argument is reasonable.
No it is not reasonable. There is no physical thing that changes about the device after it has been running x seconds. Changing the reference frames and comparing the energy across them is something you already recognized that you can't do; have you forgotten? You don't get to start doing it yourself now that you find it convenient. His argument just ignores the problem that would be obvious if you just did it right and stuck to a single frame.
I don't think the assertion you made (highlighted above) is correct. I have spent a bit of time arguing in support of the short over unity paper that Woodward released on the Mach Effects Thread. While I know I was never able to get past the need to reset in order to avoid over unity problems Woodward rebuked in the prior half of the paper. One thing did jump out at me. Every time this disagreement arises, proponents try to explain this via an example of a rocket. However, because devices governed by Mach Effects don't work like rockets we are implicitly asking critics to accept some handwaving. Which they don't and we continue talking past each other. How about we reset this part of the conversation by asserting that devices governed by Mach Effects do not work like rockets and examples using rockets to explain how they work are inherently flawed and should be used with EXTREME CARE.
Now, according to Woodward an ME device is physically changing constantly. The fluctuating mass component is having its mass vary over time. In addition, there is an actuator force pushing against the fluctuating mass when it is heavier and pulling on it when it is lighter. So for me if there is the potential for a reset/re-gauge to take place.
Personally, I have come to think of devices governed by ME as basically row boats treating inertia as their ocean. With the difference being that while a person operating a row boat has to pull their Orr out of the water during a release. a device governed by ME simply reduces the mass of the water during the release just before the recovery phase where the Orr is returned to its previous position to prepare for another catch. Then just before the catch is initiated the mass of the water is increased and the extraction phase begins again. This cycle is repeated over and over till you get to where you are going. Now, let us assume it is an infinite glassily still body of water, where for additional simplicity there is zero air friction. In this experiment as we all know for every increment of velocity, I would like to gain in my direction of motion I need to put more energy in than I did on my previous stroke. That is because the water I am using to push off of is not moving at all. So the minute I initiate the catch the friction from the water will begin draining away the boat's momentum and transfer it to the water colliding with the Orr. Now, what happens if we change the experiment a bit and dictate that the glassy water is constantly moving in the opposite direction of my motion. In this case, I now need to put even more energy into the Orr in order to continue moving in the direction I have chosen. How about if the direction of motion of the glassy water is always moving in the same direction the boat is moving in but always at the same speed that the boat is moving in. In this later case, I would never need to put in more energy than I originally needed to begin moving in the first place.
Like the many rocket examples that have been used to try and explain why there is no over-unity problem. There is a critical assumption I am making that doesn't seem to be obviously true in the case of a thruster device governed by ME driven starship, instead of a row boat. That assumption is having the glassy-surfaced water magically always moving in the same direction of motion as the boat at the same speed the boat is moving at. In the case of a ME governed thruster that glassy-surfaced water is really the fluctuating mass within the thruster. The Orr becomes a piezo electric acctuator; and the boat is the rest mass that is attached to the actuator. From what I have understood from Woodward's description of operation. While the thing you are pushing off of is the Fluctuating Mass (only when its mass is heaviest), the reason any momentum can be transferred at all to the Rest mass is because of inertia. Inertia is trying to resist having that fluctuating mass move in the direction the actuator is pushing in; thereby generating an equal but opposite force in the desired direction of motion. Now the reason I believe the idea of a reset/re-guage is valid. Is because what really governs your acceleration is the difference between the inertial force resisting the pull from the release position back to the catch position and the inertial force resisting the push from the catch position to the finish position. Given what little I know if the equations of motions involved. The reset wouldn't occur because the actuator moved the fluctuating mass from release position to catch position. It occurs during mass fluctuation; since that is the only thing that would alter the magnitude of the inertia the actuator would experience.
Now if our thruster governed by Mach Effects, was limited to only being able to attain a mass fluctuation of +/- 10% of rest mass. Then eventually there is a terminal velocity for this particular thruster configuration. This arises because on every stroke the actuator must be able to change the direction of the Fluctuating Mass component opposite to the path of acceleration. This will be trivial on the recovery phase of the stroke. It will not be on the extraction phase. On the extraction phase, the force that can be extracted will be explicitly governed by two things.
1. What is the maximum pushing force the actuator can generate?
2. What is the maximum deviation from rest mass that the thruster can generate on the fluctuating mass component?
so if our mass fluctuation is limited to +/- 10% of rest mass then eventually we will attain a speed equal to the maximum pushing force for the actuator. Since the actuator has to oppose that force to move the fluctuating mass back to the finish position.
This means in order to get constant acceleration. You must continue to increase the magnitude of the mass fluctuation. Unfortunately, I doubt nature will be nice enough to grant us the ability to infinitely alter the fluctuating mass. At a maximum If we increase the mass too much, I would think that we run a decent shot at creating a black hole. So to maintain a constant acceleration for a notable period of time I would assume given an actuator with a fixed pushing force. You would alter the delta of the fluctuating mass component's increase and decrease based on what the current velocity is. As our velocity increases, we would aim to keep the fluctuating mass component increases at the point where the actuator can maintain its maximum pushing force; irrespective of the increasing kinetic energy of the ship as a whole. While also keeping the fluctuating mass component decreases at least to the point where the difference in Flarger - Fsmaller is as large enough to maintain dialed in level of acceleration.
P.S.
The rowing terminology used in the row boat example were taken from the Rowing (Sport) article in wikipedia
. I'm just an old girl engineer that's trying to wrap my head around some of the maths. I'm indebted to you all. 