Monomorphic, of these two forms in which is it easiest to develop a strong (and therefore better) resonant state? thnx, FL
I have run a fair number of sims on the wedge geometry, but I have only run one rough sweep on the wedge-pizza. I cannot say anything definitive at this time.
Dear all
...
I will admit that this takes me way beyond my pay grade and I'm just now slowly getting a grasp of what you did.
The one question I'd have for you and maybe anyone here is to clear up why the stress seems to be increasing as the equation progresses in time? We are looking at a relative short time in cycles (<5) and I see a growth. The question begs to be answered, what happens if it's extended a few thousand cycles?
Shell
I don't think that the cyclic average is increasing with time.
It cannot grow with time, according to the equations presented, which are functions of the cosine of time (a cyclic function with time that cannot grow with time over many cycles). There is no function of time outside the cosine function in any of the equations presented.
Looking at the equations, all you have are cosine variations with time and phase.
(Essentially, Cos2 [ω t'] variation for the time-time component (density of relativistic mass) and Cos[2 ω t' + δ] for the normal stress components):
in which there is 
a) Ttt (this time–time component is the density of relativistic mass = mass/Volume, i.e. since E = m c2, m/V= (E/V)/c2, the energy density divided by the speed of light squared),
and
b) The normal, diagonal, stress components Tzz, Trr, Tφφ .
Ttt (the density of relativistic mass = mass/Volume) is a function of the inverse of Cos2 [ω t'] (a cosine does not grow with time, but it varies cyclically with time) plus a constant (*).
The normal stress components, for example Tzz are functions of Cos[2 ω t' + δ] (again, a cosine does not grow with time, but it varies cyclically with time).
Therefore, all you can have, as remarked by the author is:
depending on the relative phase delta (blue line 0, red line pi/2, green line pi) there are amplitude differences between the wave fields above and below the resonator
The question begs to be answered, what happens if it's extended a few thousand cycles?
Shell
ANSWER: According to the equations presented the cyclic average will not grow with time, not in a thousand cycles, nor in a billion cycles, nor in an infinite number of cycles
_________________
(*) t' = t - tret
The term Cos2 [ω t'] is summed to a constant and squared, and it appears in the denominator. None of that changes its cyclic character. Its cyclic average cannot grow with time.
I figured that out Dr. Rodal. Its cyclic nature does have a finite period of growth and decay my question is what is it? In his example of a symmetrical hollow waveguide they would cancel each other out.
And how would a asymmetrical cavity such as the Frustum effect that pattern?
This relates back to the stress calculations you did on other cavities where the stress components and you showed that the stress was unequal. I've attached a Big End Stress calculation you did. They showed that the stress components were unequal end to end.
A single larger one would be more efficient. Make it two if you seek reliability/robustness.
Heat Dr. Rodal, heat is the killer of a high Q system. This way you could pulse them for a specific duty cycle and let the thermal issues with a high power run at a very high Q settle down.
Shell
But that's the point of using a larger cavity: the dissipated heat is smaller using a larger cavity than by using several smaller cavities.
This is even more important in superconducting cavities: to minimize the internal surface area per unit volume.
There are so many practical issues regarding size and fabrication. If high-Q is indeed key, then better results are obtained with a larger thrustum (that's my new name for an emdrive - thrusting frustum = thrustum) because imperfections of fabrication shouldn't matter so much. But at some point, this becomes unwieldy. From where I sit (which isn't so close to the action), it seems that the scale currently being worked on is most convenient for fabrication, test, and measurement.
When it comes to application, I forsee a thrustum being precision manufactured en masse, and a single unit perhaps the size of a common washing machine. It will make economic sense to utilize more of a standard device, rather than have a number of differing sizes, from those the size of a battleship to those the size of thimbles.
Further, in practical use, it makes sense to have redundancy. Losing one of a thousand thrustums on an interstellar vessel is far less of a problem than having one or a dozen large thrustums that must be kept in tip-top shape.
Take it as you will, this is just commentary from the peanut gallery.
...
I figured that out Dr. Rodal. Its cyclic nature does have a finite period of growth and decay my question is what is it? In his example of a symmetrical hollow waveguide they would cancel each other out.
And how would a asymmetrical cavity such as the Frustum effect that pattern?
This relates back to the stress calculations you did on other cavities where the stress components and you showed that the stress was unequal. I've attached a Big End Stress calculation you did. They showed that the stress components were unequal end to end.
There is no finite period of growth and decay in DaCunha's solution. The cyclic nature is composed of a function of the inverse of the square of the cosine and another of the cosine of twice the frequency.
In DaCunha's analysis it will not grow in twenty cycles or a thousand cycles or in an infinite number of cycles.
The stress calculations I performed have an entirely different behavior: they grow exponentially with time (it is an exponential transient growth). There is no exponential transient growth expression in the equations presented by DaCunha.
The reason for this difference has nothing to do with geometry but it has to do with the fact that DaCunah assumed from the beginning a cyclic response. He did not model a transient exponential response.
...
While I chose the stress components Trr,Tphiphi,Tzz
to be oscillating with the same frequency but with a possible different phase delta relative to the oscillating energymass flow.
in which there is
....
Bold added for emphasis
______________
PS: As TheTraveller has written in other posts, any electromagnetically resonant cavity (even one with a constant cylindrical cross-section with no taper), will go through a transient response.
Reason for transient: cavity filling time
But, again, no transient response has been modeled by DaCunha, not in the graph discussed, nor in his equations.
There is no growth in the DaCunha graph you referred to:
All there is the cyclic intereference of the cyclic behaviors described by his cyclic equations.
... Yes, if G-drive works, it can be used to solve all energy needs - the orbit of the Earth changes little by little indeed, but we can handle it...
Thanks for your honest answer that << if G-drive works, it can be used to solve all energy needs >>
It is very puzzling that other people that claim that the EM Drive can provide constant force for constant electric power input discuss projects like interstellar probes and mundane transportation instead of using it to solve the energy crisis, which by any financial consideration should be a much more immediately rewarding financial use, and for which there is a much larger pool of venture capital for funding R&D.
Also, why do people discussing the EM Drive even consider LENR, conventional nuclear power and other power sources when rotating EM Drives themselves could be used to generate the needed power for transportation and propulsion purposes? (if the EM Drive does provide constant force for constant power input, as claimed by Shawyer, McCulloch, etc.)
OK, I'll bite. Frankly I don't get the objection. To me it would seem that if you try to tap any power out of this setup, you will experience a counter-force that would quickly deplete and overwhelm the input source. To my way of thinking EM Drive operates more like a motor than an "engine". You are exchanging electrical energy for momentum, and not all that efficiently, but a lot better than a photon rocket. But the vacuum energy that is being exchanged for momentum is being done only because energy is being supplied to the system. I don't see over unity being extracted from the vacuum energy. Thus in the illustration that has proceeded as soon as you put in a load on the "generator" attached to the rotating EM Drives, the counter-rotational resistance force being applied by the generator would quickly overwhelm the rotating EM Drives as soon as the load tries to extract any kind of power that nears the supplied input power, let alone tries to go above it. All power ultimately is coming from the supplied input electrical power in that illustration. No? Otherwise, why the need to supply input power after the thing starts rotation? Constant force with constant power in is fine, but once force is met with counter-force, motion would cease unless more power was input. Right? Any rotating devices, even if in a vacuum, will come up against practical frictional (heat) barriers at the "bearing" such that it cannot keep accelerating forever. Same is true for an EMDrive approaching c. It's relativistic mass will grow and if 'F' is constant 'a' must shrink. ? Or are you discussing the so-called "reverse" case? Where Shawyer claims you can derive electrical power from an EM Drive that is already in motion? I agree that is a case I have a hard time with. I remember once discussing the possibility of extracting energy from a reference frame that is not net zero with the Cosmic Microwave Background Anisotropy, but I don't believe it. Sounds like that is just an excuse for a preferred reference frame.
...
OK, I'll bite. Frankly I don't get the objection. ...
Please search for the posts by Frobnicat (preferably using "Google Advanced Search", who has thoroughly dealt with this, including frame-indifference, and the issues you discuss. Frobnicat has a lot of posts discussing this in previous threads.
The stretching of the wavelength
Why not use the correct name / term? IE, increasing guide wavelength?
I have found the term "wave-vector", symbol "k" often used; k= 2 pi / lambda, where lambda is the guide wavelength.
Should add that as guide wavelength increases, group velocity decreases.
Often true in practice, not necessarily in theory. Group velocity (Vg) = d omega / d k, in general over a typically small d omega. Group velocity is dispersion, its slope (group velocity dispersion) changes rapidly approaching resonances and cutoffs.
...There are so many practical issues regarding size and fabrication. If high-Q is indeed key, then better results are obtained with a larger thrustum (that's my new name for an emdrive - thrusting frustum = thrustum) because imperfections of fabrication shouldn't matter so much. But at some point, this becomes unwieldy. From where I sit (which isn't so close to the action), it seems that the scale currently being worked on is most convenient for fabrication, test, and measurement.
When it comes to application, I forsee a thrustum being precision manufactured en masse, and a single unit perhaps the size of a common washing machine. It will make economic sense to utilize more of a standard device, rather than have a number of differing sizes, from those the size of a battleship to those the size of thimbles.
Further, in practical use, it makes sense to have redundancy. Losing one of a thousand thrustums on an interstellar vessel is far less of a problem than having one or a dozen large thrustums that must be kept in tip-top shape.
Take it as you will, this is just commentary from the peanut gallery.
See these posts:
https://forum.nasaspaceflight.com/index.php?topic=39772.msg1511704#msg1511704How would you address the fact that for turbofan jet engines, instead of having dozens of small jet engines, we have gone from 4 (or 8) jet engines for large airplanes in the 50's to only two large engines nowadays ?
It is because of energy consumption and
the cost of energy. Large engines are more efficient.
Of course if indeed you could use a couple of rotating EM Drives to freely supply all the power you need to a third EM Drive for space propulsion , (or you have some other means to provide practically free power) and you need no external power (no nuclear power etc.) and energy is no longer a problem, then again size may not be an issue any longer...and what you wrote applies
So why the missing side walls in Roger's SC cryo EmDrive thruster?
Just maybe the top and bottom Rf mirrors (let's call them what they are) direct & beam the microwave photons from end to end without letting them hit the side walls?
If so there should be a BIG effect on reducing eddy current losses (no side walls), boosting Q (desired goal is increased cavity discharge time) to harvest the max momentum transfer (maxed number of Rf mirror reflections) from a short initial Rf excitation pulse.
The Thrust curve that is there after the Rf pulse ends is due to retained cavity energy slowly decaying, yet still capable of generating force. The less the losses in the cavity during the decay time (from no eddy currents induced in the missing side walls), the longer the cavity energy will remain active and generate force.
I consider these two images as being major breadcrumbs from Roger to DIY EmDrive researchers/builders. Would suggest the missing side walls will also work with non SC cryo frustums. However the end plates need to be very good Rf mirrors that can very accurately direct and beam the microwave photons back and forth between the 2 Rf mirrors without touching the side walls.
Rather than getting in an argument with you about what is going to happen if you remove the side walls from an electromagnetically resonant cavity at microwave frequencies with perfect convex and concave "mirrors" between the ends (*), a note of warning to anybody reading this:
BE SAFE, escaping microwave radiation is hazardous to your health. (*) There is no need to argue: this can be modeled with FEKO, COMSOL, ANSYS or any other such program
(*)
A maser is not a laser 
...
The Df in his Accelerative Reaction Force equation
Force = (2 Qu Pwr Df) / c
Is based on guide wavelength variation between the ends, which is now very clearly shown to be happening.
Guide wavelength variation. Ah! You mean dispersion?
BTW is there any way to plot / display the guide wavelength changes between the end plates?
I know MPD (Meep's freq domain predecessor) calculates and so can plot Vg, in terms of Bloch wave vectors, which may do. A problem, I fear, is it may not be applicable for an accelerating and decelerating (Doppler) particular time-domain case such as ours.
http://forum.nasaspaceflight.com/index.php?action=dlattach;topic=39772.0;attach=1108330Interesting equation. On the left side, I see a scaling factor involving the Abraham momenta / Minkowski momenta. On the right side, I see dispersion.
I believe there is a third term missing, a term showing the system is open and not closed, and will chill our hopes a bit.
So why the missing side walls in Roger's SC cryo EmDrive thruster?
Just maybe the top and bottom Rf mirrors (let's call them what they are) direct & beam the microwave photons from end to end without letting them hit the side walls?
If so there should be a BIG effect on reducing eddy current losses (no side walls), boosting Q (desired goal is increased cavity discharge time) to harvest the max momentum transfer (maxed number of Rf mirror reflections) from a short initial Rf excitation pulse.
...
Rather than getting in an argument with you about what is going to happen if you remove the side walls from an electromagnetically resonant cavity at microwave frequencies with perfect convex and concave "mirrors" between the ends (*), a note of warning to anybody reading this: BE SAFE, escaping microwave radiation is hazardous to your health.
(*) There is no need to argue: this can be modeled with FEKO, COMSOL, ANSYS or any other such program
(*) A maser is not a laser
Oh dear. That was so messed-up. That's why I'm tempted to be a pedantic jerk of an engineer when there's discussion of photons, when, (in my lame humble opinion) there ought to be discussion of fields. I recently reviewed three of UTEP prof. Rumpf's EM courses, and it all involved field theory, occasional mention of photonic lattices, optics a couple times. Never any discussions of photons or probabilities. None. All calculations involved E, B, Poynting vectors, et. No photons. No probabilities. No QM/QED. Photons obfuscate and confuse, IMHO.
...There are so many practical issues regarding size and fabrication. If high-Q is indeed key, then better results are obtained with a larger thrustum (that's my new name for an emdrive - thrusting frustum = thrustum) because imperfections of fabrication shouldn't matter so much. But at some point, this becomes unwieldy. From where I sit (which isn't so close to the action), it seems that the scale currently being worked on is most convenient for fabrication, test, and measurement.
When it comes to application, I forsee a thrustum being precision manufactured en masse, and a single unit perhaps the size of a common washing machine. It will make economic sense to utilize more of a standard device, rather than have a number of differing sizes, from those the size of a battleship to those the size of thimbles.
Further, in practical use, it makes sense to have redundancy. Losing one of a thousand thrustums on an interstellar vessel is far less of a problem than having one or a dozen large thrustums that must be kept in tip-top shape.
Take it as you will, this is just commentary from the peanut gallery.
See these posts:
https://forum.nasaspaceflight.com/index.php?topic=39772.msg1511704#msg1511704
How would you address the fact that for turbofan jet engines, instead of having dozens of small jet engines, we have gone from 4 (or 
jet engines for large airplanes in the 50's to only two large engines nowadays ?
Because jet engines had improved to the point where this was feasible? In times past materials science, machining and design were not as advanced. I always assumed that the probability of failure was factored into how many engines were bolted on. I know that in the old days, two engine aircraft were not considered reliable enough for transatlantic flight.
It is because of energy consumption and the cost of energy. Large engines are more efficient.
There is operational efficiency and then there is fabrication efficiency. Economic efficiency is these two in concert.
Of course if indeed you could use a couple of rotating EM Drives to freely supply all the power you need to a third EM Drive for space propulsion , (or you have some other means to provide practically free power) and you need no external power (no nuclear power etc.) and energy is no longer a problem, then again size may not be an issue any longer...and what you wrote applies
But if you have practically free power available and Q is not much of an issue, why bother with superconductivity?
That's a separate issue. But well yes, if you had "free energy" then why build them large?
Maybe I shouldn't have bothered with my post. Getting efficiency is getting the cart before the horse. We're still in proof-of-concept stage here.
... Getting efficiency is getting the cart before the horse. We're still in proof-of-concept stage here.
, and thank you for your post. All good points.
QUESTION: We were discussing the proposal of 8 superconducting cavities for a SSTO or an interstellar probe. Then why bother with superconductivity, if efficiency and Q is getting the cart before the horse?
...That's why I'm tempted to be a pedantic jerk of an engineer when there's discussion of photons, when, (in my lame humble opinion) there ought to be discussion of fields. I recently reviewed three of UTEP prof. Rumpf's EM courses, and it all involved field theory, occasional mention of photonic lattices, optics a couple times. Never any discussions of photons or probabilities. None. All calculations involved E, B, Poynting vectors, et. No photons. No probabilities. No QM/QED. Photons obfuscate and confuse, IMHO.
That's a great way to think about this:
think about fieldsThank you, I will borrow that in the future to explain the difference.
So why the missing side walls in Roger's SC cryo EmDrive thruster?
Just maybe the top and bottom Rf mirrors (let's call them what they are) direct & beam the microwave photons from end to end without letting them hit the side walls?
If so there should be a BIG effect on reducing eddy current losses (no side walls), boosting Q (desired goal is increased cavity discharge time) to harvest the max momentum transfer (maxed number of Rf mirror reflections) from a short initial Rf excitation pulse.
...
Rather than getting in an argument with you about what is going to happen if you remove the side walls from an electromagnetically resonant cavity at microwave frequencies with perfect convex and concave "mirrors" between the ends (*), a note of warning to anybody reading this: BE SAFE, escaping microwave radiation is hazardous to your health.
(*) There is no need to argue: this can be modeled with FEKO, COMSOL, ANSYS or any other such program
(*) A maser is not a laser
Oh dear. That was so messed-up. That's why I'm tempted to be a pedantic jerk of an engineer when there's discussion of photons, when, (in my lame humble opinion) there ought to be discussion of fields. I recently reviewed three of UTEP prof. Rumpf's EM courses, and it all involved field theory, occasional mention of photonic lattices, optics a couple times. Never any discussions of photons or probabilities. None. All calculations involved E, B, Poynting vectors, et. No photons. No probabilities. No QM/QED. Photons obfuscate and confuse, IMHO.
Yet there are no side walls in Rogers SC cryo EmDrive thruster!. Seems Roger's design is not what you may believe it is. It amazes me how good folks here refuse to believe what their eyes see and postulate a different & incorrect understanding of what Roger has built.
BTW here is another set of Rf mirrors (big concave and small convex as Roger uses) that forms and directs microwave photons without needing side walls. By altering the curvature of the convex secondary, the Rf photons could be made to transit between the Rf mirrors until eddy currents killed the signal.
So why the missing side walls in Roger's SC cryo EmDrive thruster?
Just maybe the top and bottom Rf mirrors (let's call them what they are) direct & beam the microwave photons from end to end without letting them hit the side walls?
If so there should be a BIG effect on reducing eddy current losses (no side walls), boosting Q (desired goal is increased cavity discharge time) to harvest the max momentum transfer (maxed number of Rf mirror reflections) from a short initial Rf excitation pulse.
...
Rather than getting in an argument with you about what is going to happen if you remove the side walls from an electromagnetically resonant cavity at microwave frequencies with perfect convex and concave "mirrors" between the ends (*), a note of warning to anybody reading this: BE SAFE, escaping microwave radiation is hazardous to your health.
(*) There is no need to argue: this can be modeled with FEKO, COMSOL, ANSYS or any other such program
(*) A maser is not a laser
Oh dear. That was so messed-up. That's why I'm tempted to be a pedantic jerk of an engineer when there's discussion of photons, when, (in my lame humble opinion) there ought to be discussion of fields. I recently reviewed three of UTEP prof. Rumpf's EM courses, and it all involved field theory, occasional mention of photonic lattices, optics a couple times. Never any discussions of photons or probabilities. None. All calculations involved E, B, Poynting vectors, et. No photons. No probabilities. No QM/QED. Photons obfuscate and confuse, IMHO.
Yet there are no side walls in Rogers SC cryo EmDrive thruster!. Seems Roger's design is not what you may believe it is. It amazes me how good folks here refuse to believe what their eyes see and postulate a different & incorrect understanding of what Roger has built.
BTW here is another set of Rf mirrors (big concave and small convex as Roger uses) that forms and directs microwave photons without needing side walls. By altering the curvature of the convex secondary, the Rf photons could be made to transit between the Rf mirrors until eddy currents killed the signal.
SAFETY !Should differentiate between far-field and near-field.The field around the RF injection is near-field.
I am genuinely worried that people are going to hurt themselves by following the suggestion to remove the metal walls from the EM Drive. THIS IS DANGEROUS! Experiments with monkeys in proximity of microwave 100 Watts resulted in death of monkeys! The human brain is most vulnerable to microwave radiation
So why the missing side walls in Roger's SC cryo EmDrive thruster?
Just maybe the top and bottom Rf mirrors (let's call them what they are) direct & beam the microwave photons from end to end without letting them hit the side walls?
If so there should be a BIG effect on reducing eddy current losses (no side walls), boosting Q (desired goal is increased cavity discharge time) to harvest the max momentum transfer (maxed number of Rf mirror reflections) from a short initial Rf excitation pulse.
...
Rather than getting in an argument with you about what is going to happen if you remove the side walls from an electromagnetically resonant cavity at microwave frequencies with perfect convex and concave "mirrors" between the ends (*), a note of warning to anybody reading this: BE SAFE, escaping microwave radiation is hazardous to your health.
(*) There is no need to argue: this can be modeled with FEKO, COMSOL, ANSYS or any other such program
(*) A maser is not a laser
Oh dear. That was so messed-up. That's why I'm tempted to be a pedantic jerk of an engineer when there's discussion of photons, when, (in my lame humble opinion) there ought to be discussion of fields. I recently reviewed three of UTEP prof. Rumpf's EM courses, and it all involved field theory, occasional mention of photonic lattices, optics a couple times. Never any discussions of photons or probabilities. None. All calculations involved E, B, Poynting vectors, et. No photons. No probabilities. No QM/QED. Photons obfuscate and confuse, IMHO.
Yet there are no side walls in Rogers SC cryo EmDrive thruster!. Seems Roger's design is not what you may believe it is. It amazes me how good folks here refuse to believe what their eyes see and postulate a different & incorrect understanding of what Roger has built.
BTW here is another set of Rf mirrors (big concave and small convex as Roger uses) that forms and directs microwave photons without needing side walls. By altering the curvature of the convex secondary, the Rf photons could be made to transit between the Rf mirrors until eddy currents killed the signal.
SAFETY !
Should differentiate between far-field and near-field.
The field around the RF injection is near-field.
The missing side walls are reality. Deal with it and maybe learn something?
What was it said about your secret project? Non metallic frustum not intended for space use or something like that?
BTW Roger does NOT use an antenna to inject the short Rf pulse into his cryo frustums.
The missing side walls are reality. Deal with it and maybe learn something?
Just don't be reckless and hurt yourself, man.
The missing side walls are reality. Deal with it and maybe learn something?
Just don't be reckless and hurt yourself, man.
Thanks for the thought.
Just maybe accept there is something going on in Roger's cryo thruster that is not understood by most here? Roger is a 30 year microwave engineer, so don't believe his design is unsafe.
Everything we know about frustum design says there is no way that open sided frustum would work. Yet there it is, staring us in the face, saying you sure you know what is going on inside me?
BTW most of my testing is done at 78mW to 10W with only very brief periods of a few seconds at 100Ws. Never get closer than 1m to the Rf amp or frustum at any time. Nice to have an Rf amp that steps in 1dBm increments from 78mW to 100W, that reports both forward & reflected power and is driven by dial up freq gen at 1kh resolution. Means I know what is exciting the frustum and can easily dial up past settings.
Don't envy those maggie builders as there is almost no way to know what is happening to the drive freq, power, cavity Q, forward & reflected power as it is all over the spectrum and the frustum is pulling the maggie freq into it's resonance but with a power penalty of phase shifted reflected Rf due to the pulling. Then altering maggie power, alters Freq due to pushing. Not an easy beast to control, if at all.
Traveller, Invar + YBCO...would this not act as a barrier to RF energy
FL
jet engines for large airplanes in the 50's to only two large engines nowadays ?
, and thank you for your post. All good points.
FL