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#2920 by D_Dom on 17 Feb, 2016 21:45
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Wow, a legendary golden hammer. I have heard tell of such things but never actually seen one before.
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#2921 by Bob Woods on 17 Feb, 2016 23:09
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Wow, a legendary golden hammer. I have heard tell of such things but never actually seen one before.
http://www.amazon.com/Bob-Builder-Golden-Hammer-The-Movie/dp/B0046H0HYC -
#2922 by masterharper1082 on 17 Feb, 2016 23:58
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Hello,
Just introducing myself to the forum, and trying to get used to the strange features of the NSF message editor.
I've been lurking for quite a while - I read all of Thread 6, but haven't gone back any further.
As a Mechanical Engineer specializing in control algorithms and physics-based simulation, I may be able to offer some assistance on topics relevant to EMDrive - especially with respect to thermal effects, cooling, or writing/modifying simulation codes in C++, C, or Matlab/Simulink. Finally, I may have some mechanisms to get access to ANSYS CFX and computation time as long as we are last in the scheduler - I can inquire if there is interest.
Yeah, my most recent patent doesn't make thrust either - it just makes a heat pump work better:
Receiver Fill Valve and Control Method
Here's more info on me courtesy of my
LinkedIn Profile.
Best wishes to all,
masterharper1082
Welcome. I'm curious, when you say you can help with thermal effects and cooling, does this mean Computational Fluid Dynamics (CFD)? There was some discussion earlier about running simulations that can estimate order of magnitude force from thermal effects, including convection and turbulence, for rfmwguy's experiment. I bet other experimenters would also appreciate modeling of these forces via CFD for their setups. In fact, I'm surprised that no one else has asked this question.
With respect to thermal effects - yes, I was primarily thinking of CFD. I am not a CFD expert, but I work with a bunch of them who might be willing to engage in coffee-break conversations about how to set it up. The biggest challenge will probably be to set up the correct temperature distribution on the outside surface of the frustum.
With respect to cooling, I was not thinking CFD, but rather refrigeration system design. I also work with technicians who are expert at copper brazing, pulling vacuum on refrigeration systems, etc., so they might have some good tips for DIYers who are trying to figure out such problems.
masterharper1082 -
#2923 by masterharper1082 on 18 Feb, 2016 00:20
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Hello,
Just introducing myself to the forum, and trying to get used to the strange features of the NSF message editor. I've been lurking for quite a while - I read all of Thread 6, but haven't gone back any further.
As a Mechanical Engineer specializing in control algorithms and physics-based simulation, I may be able to offer some assistance on topics relevant to EMDrive - especially with respect to thermal effects, cooling, or writing/modifying simulation codes in C++, C, or Matlab/Simulink. Finally, I may have some mechanisms to get access to ANSYS CFX and computation time as long as we are last in the scheduler - I can inquire if there is interest.
Yeah, my most recent patent doesn't make thrust either - it just makes a heat pump work better:
Receiver Fill Valve and Control Method
Here's more info on me courtesy of my
LinkedIn Profile.
Best wishes to all,
masterharper1082
Welcome. I'm curious, when you say you can help with thermal effects and cooling, does this mean Computational Fluid Dynamics (CFD)? There was some discussion earlier about running simulations that can estimate order of magnitude force from thermal effects, including convection and turbulence, for rfmwguy's experiment. I bet other experimenters would also appreciate modeling of these forces via CFD for their setups. In fact, I'm surprised that no one else has asked this question.
With respect to thermal effects - yes, I was primarily thinking of CFD. I am not a CFD expert, but I work with a bunch of them who might be willing to engage in coffee-break conversations about how to set it up. The biggest challenge will probably be to set up the correct temperature distribution on the outside surface of the frustum.
With respect to cooling, I was not thinking CFD, but rather refrigeration system design. I also work with technicians who are expert at copper brazing, pulling vacuum on refrigeration systems, etc., so they might have some good tips for DIYers who are trying to figure out such problems.
masterharper1082
To elaborate and respond to Dr. Rodal's comments:
1. I am a "he", not a "she"
2. I was not thinking of the multi-physics problem inside the frustum, but rather the natural convection flow problem outside the frustum. That could probably be treated as more of a standard CFD problem. The first step would most likely be a steady-state solution, but even a transient solution of this problem is much more tractable than going after the "inside the frustum" problem. For the external problem, I would expect the slanted side walls, differing end plate areas, and complex surface temperature distribution to produce a net side force (assuming frustum is mounted laterally), even if there was no net side force from the internal convective flow.
3. Until proven incorrect, I am assuming that a *sealed* frustum would not produce any side force from internal convective flow. Without a crack to allow air inflow/outflow, the *average* density of the closed control volume would not change, even if the pressure/temperature changed (assuming minimal bulging of the frustum walls).
masterharper1082 -
#2924 by rfmwguy on 18 Feb, 2016 02:24
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Housekeeping note - Let's start T7 off when warptech's full paper is released. It should be the first post there. Help me keep an eye out for it via PM. Thanks in advance.
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#2925 by Mulletron on 18 Feb, 2016 10:08
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I checked around and it appears that an induced gravitoelectric field is a non-conservative field (just like the induced EM electric field is), at least on paper...there's no experiment to prove the gravitational analogue. I didn't find any good math for it yet. The information is very light about this. The implications of doing classical mechanics in the presence of a non-conservative gravitational field? ....I guess I'll just stop right there.
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#2926 by CW on 18 Feb, 2016 15:22
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I checked around and it appears that an induced gravitoelectric field is a non-conservative field (just like the induced EM electric field is), at least on paper...there's no experiment to prove the gravitational analogue. I didn't find any good math for it yet. The information is very light about this. The implications of doing classical mechanics in the presence of a non-conservative gravitational field? ....I guess I'll just stop right there.
I think that there is a lot of unexplored territory. -
#2927 by birchoff on 18 Feb, 2016 16:21
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I checked around and it appears that an induced gravitoelectric field is a non-conservative field (just like the induced EM electric field is), at least on paper...there's no experiment to prove the gravitational analogue. I didn't find any good math for it yet. The information is very light about this. The implications of doing classical mechanics in the presence of a non-conservative gravitational field? ....I guess I'll just stop right there.
I think that there is a lot of unexplored territory.
Any of that unexplored territory come with concrete practical experiments to determine physicality of the ideas. -
#2928 by X_RaY on 18 Feb, 2016 19:55
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My FEKO LITE results and current status of exploring the free trial version of the program.
https://forum.nasaspaceflight.com/index.php?topic=39214.msg1491571#msg1491571 *
*It's really worthwhile to read the whole thread!
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#2929 by JohnFornaro on 18 Feb, 2016 20:31
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Wow, a legendary golden hammer. I have heard tell of such things but never actually seen one before.
http://www.amazon.com/Bob-Builder-Golden-Hammer-The-Movie/dp/B0046H0HYC
Maxwell's silver one didn't hold up. -
#2930 by spupeng7 on 18 Feb, 2016 23:14
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The definition of Quality Factor is:
it is an inverse measure of damping ζ: the lower the damping ζ of the oscillation, the higher the Q, it is used for acoustic resonance, vibrations of structures, electromagnetic resonance, etc. etc.
It is related to the damping constant ζ and the exponential time constant τ as follows:
Q=π τ frequency
=π τ/period
τ = Q / (π frequency)
= Q*period/π
so, after turning off the excitation, resonance will decay with time t exponentially:
N(t)/ No = e- t frequency π/Q
af a fixed frequency, the higher the Q, the longer the time t can be for a given ratio of N(t)/No
The time constant τ is the mean lifetime of the exponential decay
We can see that τ is the time t at which the intensity is reduced to e-1 = 0.367879441 times its initial value, since Q is proportional to the mean lifetime τ you can think of Q as a measure of Pi times the (mean lifetime)*frequency of resonance after your turn the excitation off.
At a constant frequency, Q is proportional to the mean lifetime of resonance without excitation.
.
For a fixed natural frequency of a bell's resonance, you can think of Q as a measure of the mean lifetime of a bell's vibration after you ring the bell.
Alternatively, since the period "T" of oscillation (the time duration of one cycle) is the reciprocal of the frequency
frequency=1/period
then
(mean lifetime)*frequency = (mean lifetime)/period
and defining
"mean number of cycles" = (mean lifetime)/(period of oscillation)
you can think of Q as a measure of Pi times the so-defined "mean number of cycles" of resonance after you turn the excitation off.
Also: comparing different natural frequencies with the same Q, the higher the natural frequency, the shorter the mean lifetime of resonance, conversely, the lower the natural frequency, the longer the mean lifetime of resonance, since Q is Pi times the mean lifetime of resonance times the natural frequency
Thankyou Dr Rodal, you always go that extra mile to improve our understanding of how all this works. Just want you to know how much we appreciate it
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#2931 by spupeng7 on 18 Feb, 2016 23:19
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Interesting. In Shawyers explanation an "initial velocity" is needed to produce any thrust.
Good news, Dr. Trunev responded to an email regarding the availability of an English translation of his papers and kindly responded.QuoteThat's why Alexander Trunev invokes General Relativity and Yang Mills field in order to justify the EM Drive as an open system so that the force is non-zero. In essence Trunev, Minotti and White all invoke the Quantum Vacuum and General Relativity to justify the non-zero net force. They all agree that under Maxwell's equations the EM Drive would experience no anomalous force/power exceeding the one for a photon rocket.
Keeping in mind this is preliminary, and we have an uncertain translation of Trunev's paper...
Are Minotti's and Trunev's theories compatible? The 'thicker skin' test for Minotti's theory has been brought up now and again. (Something our DIY crowd should look into.) Would this test also be a way of investigating Trunev's theory?
Also, are the theories of Minotti and Trunev compatible with the 'bigger is better' frustum concept?
Is the 'Not-so-sure-of-it' theory compatible with those of Minotti and Trunev?
"thank you for your interest in my article GENERAL RELATIVITY AND THEORY OF ELECTROMAGNETIC DRIVE published on http://ej.kubagro.ru/2015/10/pdf/61.pdf. I recommend also to read the second article on this subject THEORY OF ELECTROMAGNETIC DRIVE WITH ELEMENTARY PARTICLES CURRENT AND VACUUM POLARIZATION on http://ej.kubagro.ru/2016/01/pdf/80.pdf
I will prepare an English translation of these two articles and publish in the next issue of the magazine in the form of an article with the addition of new results."
Thank you,
Alexander Trunev
That's going to make TT smile a bit.
" It is found that the pulse modulation greatly improves the efficiency of conversion of electromagnetic energy into thrust. "
I am ´relative´ confused because of an initial velocity is given all the time. The earth rotates and is traveling around the sun, the sun system travels around the center of the milky way and our galaxy moves rapidly into the direction of the great attractor and so forth. So this point of view is only useful in our reference frame relative to the exterior of the cavity i.e. in relation to the gravity/quantum fields nearby.
Is it possible that a vibration could cause enough mechanical distortion to allow a resonance to establish itself in a less than perfectly tuned frustum/oscillator setup? -
#2932 by Rodal on 18 Feb, 2016 23:35
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...
Unfortunately the frequency of mechanical vibrations is too many orders of magnitude smaller than the frequency of the electromagnetic resonance in these cavities. For example, for the EM Drive typical natural frequencies excited have been around two gigaHertz (2 *10^9 Hz), while mechanical vibration frequencies are typically kiloHertz or lower, say 2*10^3 Hz or lower, which is about a million times lower frequency.
Is it possible that a vibration could cause enough mechanical distortion to allow a resonance to establish itself in a less than perfectly tuned frustum/oscillator setup?
So, with respect to the electromagnetic frequency, mechanical frequencies of vibration are so much smaller (a million times smaller than electromagnetic frequencies) as to appear practically static in comparison with the electromagnetic frequency. Worse than that, if anything, permanent geometrical distortion of a cavity usually has a deleterious effect on the quality of resonance Q, and so will mechanical vibration (if the vibration has a very high amplitude) since changing the shape of the cavity changes the natural frequency, and hence lowers the Q (assuming that one was operating at the peak resonance for maximum Q).
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#2933 by RotoSequence on 19 Feb, 2016 02:04
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...
Unfortunately the frequency of mechanical vibrations is too many orders of magnitude smaller than the frequency of the electromagnetic resonance in these cavities. For example, for the EM Drive typical natural frequencies excited have been around two gigaHertz (2 *10^9 Hz), while mechanical vibration frequencies are typically kiloHertz or lower, say 2*10^3 Hz or lower, which is about a million times lower frequency.
Is it possible that a vibration could cause enough mechanical distortion to allow a resonance to establish itself in a less than perfectly tuned frustum/oscillator setup?
So, with respect to the electromagnetic frequency, mechanical frequencies of vibration are so much smaller (a million times smaller than electromagnetic frequencies) as to appear practically static in comparison with the electromagnetic frequency. Worse than that, if anything, permanent geometrical distortion of a cavity usually has a deleterious effect on the quality of resonance Q, and so will mechanical vibration (if the vibration has a very high amplitude) since changing the shape of the cavity changes the natural frequency, and hence lowers the Q (assuming that one was operating at the peak resonance for maximum Q).
Piezoelectric devices might be able to oscillate at the requisite frequencies, but it would be nice to kill two birds with one stone and test a low frequency EM drive and a lower frequency mechanical agitator in the same setup. -
#2934 by Pdgenoa on 19 Feb, 2016 05:00
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Due to the wide range of people that have interest in this discussion its been noted that while there are a great many professionals here with various depths of expertise in all the fields this involves, there are also many that are laypersons with little or no expertise in any of the related fields - but are very engaged and curious. I'm in that category.
With that in mind my question is simple but has been very difficult for me to find an answer to, so:
It seems the primary sticking point of this device is the apparent violation of the law of conservation of momentum. My confusion is that there must be a device for creating the microwaves. That device must be powered in some way to produce the microwaves. So how is that not considered the "fuel" source? Energy is being expended to create microwaves which are then eventually fired out of the chamber. This seems to me to not violate that law. Now since I'm very aware of my ignorance in this I'm guessing this has been thought of by others and dismissed. My belief is that it's dismissed because microwaves are not something that have mass? But if that's the case I thought light didn't either yet I was under the impression that lasers can produce thrust.
You see my confusion. I sincerely hope someone can educate me on why this doesn't explain the problem without having to walk me through so many other things it would be a waste of their time. But I would greatly appreciate the effort.
Note: directing me to another place for an explanation would be fine too - as long as I can finally get this question out of my head. Thank you. -
#2935 by Rodal on 19 Feb, 2016 12:03
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A piezoelectric device may be able to oscillate a micrometer or nanometer piezoelectric actuator at GigaHertz frequencies (using MEMS technologies ( https://en.wikipedia.org/wiki/Microelectromechanical_systems )), but the micrometer actuator GHz oscillation will not result in gigahertz mechanical resonance of the macro-electromechanical device that is the EM Drive copper cavity (being discussed here, which have lengths of 0.23 meters: dimensions of several inches), which was the subject of the question:...
Unfortunately the frequency of mechanical vibrations is too many orders of magnitude smaller than the frequency of the electromagnetic resonance in these cavities. For example, for the EM Drive typical natural frequencies excited have been around two gigaHertz (2 *10^9 Hz), while mechanical vibration frequencies are typically kiloHertz or lower, say 2*10^3 Hz or lower, which is about a million times lower frequency.
Is it possible that a vibration could cause enough mechanical distortion to allow a resonance to establish itself in a less than perfectly tuned frustum/oscillator setup?
So, with respect to the electromagnetic frequency, mechanical frequencies of vibration are so much smaller (a million times smaller than electromagnetic frequencies) as to appear practically static in comparison with the electromagnetic frequency. Worse than that, if anything, permanent geometrical distortion of a cavity usually has a deleterious effect on the quality of resonance Q, and so will mechanical vibration (if the vibration has a very high amplitude) since changing the shape of the cavity changes the natural frequency, and hence lowers the Q (assuming that one was operating at the peak resonance for maximum Q).
Piezoelectric devices might be able to oscillate at the requisite frequencies, but it would be nice to kill two birds with one stone and test a low frequency EM drive and a lower frequency mechanical agitator in the same setup.QuoteIs it possible that a vibration could cause enough mechanical distortion to allow a resonance to establish itself in a less than perfectly tuned frustum/oscillator setup?
(Bold added for emphasis)
There is a fundamental difference here: the electromagnetic oscillation in the microwave cavity with a given quality of resonance Q is an oscillation of the electromagnetic fields involving the speed of light and not at all a mechanical oscillation of the copper cavity.
The impractical nature of getting the EM Drive copper cavity structure to resonate at GigaHertz frequencies can be illustrated by the following: one thing is to have GigaHertz frequencies of electromagnetic waves in a medium at the speed of light, such that the wavelength is
wavelength = c/frequency
c = 299792458 m / s
for example, at 2.45 GHz,
wavelength = 299792458/2.45*10^9 = 0.122 m = 4.82 inches
compared to mechanical resonance of the EM Drive cavity, with a copper sound speed (*) of
3560 m/s
wavelength = 3560/2.45*10^9 = 1.453 micrometers
So, a frequency of 2.45 GHz involves mode shapes in copper with a wavelength of the order of only 1.453 micrometers, which is a thousand times less than the mm thickness of the copper walls !
This is in the same dimensional scale as the skin depth of penetration of the electromagnetic fields into the copper wall (a micrometer).
It is not physically possible to excite such a mechanical resonance of the microwave cavity. Even if one would use a high explosive, all one would get would be stress wave transient strains in the copper (probably resulting in fracture of the copper wall), but not a GHz mechanical resonance of the cavity.
If one would put a tiny (less than a micrometer in dimension) piezoelectric actuator oscillating at GHz on the EM Drive copper walls, this would not make the 0.23 meter long EM Drive cavity resonate at GHz frequency.
Furthermore it is important to understand that even if one could make a (hypothetically thin) EM Drive cavity (with hypothetical walls thinner than a micrometer) to move at 2.45 GHz with a wavelength of 1.453 micrometers this would not at all produce any sympathetic resonance of the electromagnetic fields in the medium inside the cavity, since the electromagnetic fields speed is the speed of light, which is orders of magnitude higher than the speed of sound in copper, and copper molecules, and their constituent particles cannot get close to the speed of light because they have mass.
You just cannot make the copper walls move in unison with the electromagnetic fields in the cavity.
_______
(*) stress waves in a solid proceed at the speed of sound in the solid, volumetric stress waves travel at a speed of
where K is the bulk modulus of elasticity of the solid and ρ is the density.
Such stress waves in a solid cannot move at the speed of light because only massless particles like photons can travel at the speed of light. The density of a solid needs to be zero, in order for its sound speed speed to be equal to the speed of light. -
#2936 by glennfish on 19 Feb, 2016 12:10
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It seems the primary sticking point of this device is the apparent violation of the law of conservation of momentum. My confusion is that there must be a device for creating the microwaves. That device must be powered in some way to produce the microwaves. So how is that not considered the "fuel" source? Energy is being expended to create microwaves which are then eventually fired out of the chamber.
I'll take a swat at this.
First, at the energy levels that microwave generators work at, it's very difficult to find any way that energy can be converted to matter. The power levels are way too low. So, it's extremely unlikely matter is being created and tossed over the side to create thrust. If there were an energy to matter conversion at these power levels it would have been seen long ago in other experiments and physics as we know it would be quite different.
Second, it is possible that one could make a photon rocket using the microwave radiation pressure. However, that's well understood physics, actual prototypes have been created, some satellites actually depend on it, but the thrust levels are many many times smaller than that reported for the EM Drive. However, the thrust levels can be exactly calculated, so the reported thrust levels are extremely unlikely to be caused by radiation pressure.
SO, if the EMdrive works, the thrust is coming from an unknown interaction with something in a way that makes most physicists declare "crackpottery".
The problem with conservation of momentum is this. When you accelerate something, it acquires kinetic energy. The difference between a baseball on the table and a pitch coming at your head. If you do the math based on the reported performance of an EMdrive, if you keep accelerating, you come to a point where the kinetic energy becomes greater than the energy expended to make you accelerate to that velocity. At that point you have more energy than you put in and you've entered the twilight zone of perpetual motion machines and free energy. At that point most physicists collapse into a black hole and leave the conversation.
Here's a higher level explanation than my rambling.
http://rationalwiki.org/wiki/EmDrive#Violation_of_conservation_laws -
#2937 by rfmwguy on 19 Feb, 2016 13:14
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Due to the wide range of people that have interest in this discussion its been noted that while there are a great many professionals here with various depths of expertise in all the fields this involves, there are also many that are laypersons with little or no expertise in any of the related fields - but are very engaged and curious. I'm in that category.
From a moderator's viewpoint, this is exactly what we want to see in these threads; people from a wide variety of backgrounds, experience and knowledge asking questions about emdrive. By reading other forums from time to time, I've noticed a tendency to pretend its a particle physics classroom with irrelevant and demeaning answers posted to questions like this (by users of questionable credentials themselves). Doesn't happen here as myself and NSF staff will not allow it.
(snip)
So, don't be afraid to ask. T1-T6 can be cumbersome to search for the answers. Users like Glennfish gave you a great answer. Welcome to the forum. -
#2938 by Monomorphic on 19 Feb, 2016 14:51
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Hello everyone! This is my first post on this forum (so I hope i'm doing it right!), but some of you may know me as a regular contributor to that other forum...
For my first post, I wanted to share some FEKO runs I did a few weeks back of a typically sized frustum but with different dipole antenna locations and orientations. The goal was to characterize the internal near fields and surface current since many say that antenna location is the "super squirrel secret sauce." Next goal is to do a frequency sweep of each of the antenna locations.
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#2939 by rfmwguy on 19 Feb, 2016 14:57
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NASA/Eagleworks Update - February 2016
First hand confirmation was received a couple of days ago that any and all information regarding the latest testing/paper review will only be released via proper NASA channels. While most of us already assumed this, it is important to repeat: information received from other sources (other than NASA itself) should be highly suspect. This is of special importance to our science writer guests and readers. IOW, NSF will only post info once it has been officially released...no leaks, no wild claims and no "insider" rumors.
While it can be difficult to wait, its best to get the information right the first time to avoid the problems of a couple of years ago.
I've been lurking for quite a while - I read all of Thread 6, but haven't gone back any further.