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#2060 by rfmwguy on 07 May, 2016 16:26
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That's the general math without values plugged in is the intent of my post....
There is specific math here (safe from deletion): http://forum.nasaspaceflight.com/index.php?topic=39214.msg1526577#msg1526577 which you are welcome to comment on.
So many of the critiques I have read do not contain real world scenarios. This is my point. I am not trying to be controversial with this statement, but those who are really interested in contributing while a huge effort on building is taking place, can prove their sincerity by helping with some of the specific math.
Also here (safe from deletion): http://forum.nasaspaceflight.com/index.php?topic=39214.msg1474347#msg1474347 -
#2061 by Rodal on 07 May, 2016 16:30
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It is not "general math" . Take another look: zero is a very significant numerical value. Electric field is zero at all internal walls of EM Drive in TE mode shape. Many fields are shown to be zero for TM modes.
That's the general math without values plugged in is the intent of my post....
There is specific math here (safe from deletion): http://forum.nasaspaceflight.com/index.php?topic=39214.msg1526577#msg1526577 which you are welcome to comment on.
So many of the critiques I have read do not contain real world scenarios. This is my point. I am not trying to be controversial with this statement, but those who are really interested in contributing while a huge effort on building is taking place, can prove their sincerity by helping with some of the specific math.
Also here (safe from deletion): http://forum.nasaspaceflight.com/index.php?topic=39214.msg1474347#msg1474347
An equation is worth countless numbers of specific numerical values, since it can be used to obtain any numerical value they want.
The only thing assumed is that resonant modes (TE and TM) are excited at the resonant frequency in a metal cavity. (This is what is claimed by all experimenters)
Several conclusions are established: for example that there is a pressure on the side walls, and thus that people that were speculating that side walls are not necessary in a superconducting EM Drive cavity are wrong. That people stating that there is no pressure on the side walls of an EM Drive with spherical ends in microwave resonance mode shapes are wrong.
That calculating a force without taking into account the pressure on the side walls is wrong.
That the stress in an EM Drive is due to just two things: the energy density and the electrostatic pressure.
That the stress in a TE mode is only due to the magnetic energy density
That pressure on any walls on an EM Drive under a TE mode is purely due to the magnetic field and the electric field is irrelevant for the TE mode pressure.
The work is under construction, more will follow regarding momentum and energy.
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#2062 by rfmwguy on 07 May, 2016 16:32
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Not all builds are the same. Mine, for example, has no transmission line (coax or waveguide) which will propagate the thermal forces you speak about. Yang and Dresden chose a different design parameter, we don't know yet what Shell has chosen...could be several things....
If I understand this, then what you have is a mechanism where the COAX cable carries force/momentum far in excess of that of a perfectly collimated photon rocket, as is required to react the forces of the EM Drive.
If so, then how does that work?
It works as with any experimental artifact, as with thermal expansion, thermal convection, etc. It has to do with how one calculates the anomalous (=unexplained) force, and how one calculates the power that it took to produce the anomalous force.
The unexplained force/InputPower may have been incorrectly calculated. If you ignore the electromagnetic momentum, then the "anomalous force" is incorrectly calculated: extra momentum seems to come magically. The actual force that is "anomalous" = unexplained, may be much smaller, negligible or non-existent. (*)
As to how such calculations matter, see this: http://www.physics.princeton.edu/~mcdonald/examples/feynman_cylinder.pdf
Suggestion: more effort should go into providing power with batteries self-integrated in the test, as done by Yang. Imagine how much time and effort would have been saved if Yang would have done that years ago.
__________
(*) Evidence of incorrect calculation of anomalous forces abounds: Yang's prior calculations, prior to using batteries.
Incorrect calculation of stresses because of using incorrect equations to calculate the stress that do not take into account the electromagnetic momentum.
I might add that we seem to be jumping rapidly from force momentum from feed lines or power leads to frustum stresses within a few posts...not having resolved either one.
Simply stated, someone should model, with real numbers, the (micro or milli) Newton force of both lines and the cavity itself in a torsional test setup. Anything less is simply not as useful IMO. -
#2063 by jmossman on 07 May, 2016 18:01
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If I'm to believe this and believe what your saying I should not waste my time chasing any data for here within lays all the answers and even Cannae with their multi-thousand dollar setup is just chasing ghosts or NASA who's anomaly still remaining are doing the same.
Shell
I am not saying that you loose your time. But that only the Battery Powered test will convince me.
The time spend with tests on external Power is not lost. The comparison of the thrust with external Power, and the thrust on batteries will be very interesting.
If the result was null on batteries and positive with external power, it will be an important confirmation of the external power artifact.
If both results are positive, the comparison of the data would be very interesting also. It would permitt to quantify, for your particular setup, the external power artifact.
May I suggest that we view SeeShells' upcoming data as a step towards untangling the unknowns surrounding the purported EM drive, rather than the final experiment to answer all questions.
The science, math, and technology we all regularly use was not developed as a single discrete jump. Instead, we have all been "standing on the shoulders of giants", with many trying to push the combined knowledge and abilities of humankind a bit further. Add in the realities of limited R&D budgets, and lofty goals really benefit from a systematic approach that breaks the larger goal into smaller and more manageable pieces.
The data from SeeShells' various experiments, combined with the distributed expertise that has graced these past 7 threads, may well yield non-trivial improvements in understanding of what some have called the EM Drive effect.... even if the experiments are not "perfect" and that further work may well be required to get to some kind of final understanding or consensus.
As SeeShells recently reminded us... "small steps".
Regards,
James -
#2064 by zen-in on 07 May, 2016 18:28
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I don't think it is necessary to run a DC ground from the Copper cone. In fact the magnetron case, unless I am mistaken, is at a very high - DC potential and if it is galvanically (a fancy word that just means there is a metal to metal connection) connected to the low voltage DC ground it may create a lethal danger. More likely though it would just short out the HV output, destroying the magnetron supply faster than you can say Oh @&%$!. Even if the magnetron did not have a high potential on its case there would be no need for a DC ground. The coax or waveguide that connects the two supplies all the ground you need. Single point ground typically refers to power supplies and the single ground point would be at the power supply; in this case the low voltage DC supply (battery) that powers the distance sensor, control electronics, indicator LEDs, etc.
Thank you. I update the sketch according to your suggestions. One thing you were mistaken is that in a microwave oven, the two filament wires are actually at -5000V potential and the case of magnetron is at 0 potential. I draw a dashed line that grounds the frustum. This is because you suggested not to have it, but I suspect See-Shell has it. Anybody, other suggestions?
I stand corrected on the high potential issue. There are no DC ground loop concerns with the cone and the RF so it can just be mechanically fastened to the Aluminum beam. It doesn't make a difference if it is electrically connected or insulated from the beam. The diagram does show 3 DC wires connecting the battery to the inverter. Only 2 are needed and they should be twisted together or wired coaxially. One twist per inch with no loose loops is sufficient. I have made high current coax from Copper tubing and heavy gauge insulated wire. The impedance of this kind of coax doesn't matter with DC. What needs to be avoided here are extra ground return paths since the current that flows through that path will interact with the geomagnetic field and produce a lorentz force. Any frame connection (connections to the beam) have to be done carefully to avoid any current along the beam. There likely would not be any frame current from the magnetron supply to the inverter so both can simply be fastened to the Aluminum beam with a good electrical connection in the interest of electrical safety; without the ground wire shown in the diagram. The DC ground post on the Aluminum beam is not needed. It's safer to not have one terminal of the battery tied to the frame. No current should flow along the beam anyway.
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#2065 by Gilbertdrive on 07 May, 2016 18:29
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If I understand this, then what you have is a mechanism where the COAX cable carries force/momentum far in excess of that of a perfectly collimated photon rocket, as is required to react the forces of the EM Drive.
If so, then how does that work?
I know very little about this type of equation. I have understood that a coaxial cable has no field outside. But, it can have magnetic field inside, is not it ?
If there is magnetic field inside the Coax, this magnetic field can give a force orders of magnitude over a photon rocket. Electric motors work with magnetic fields, and electric cars are very more efficient that photon rockets
In fact, there are even far more efficient that Cannae Superconducting.
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#2066 by Tellmeagain on 07 May, 2016 19:10
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Have a little time before I get busy.
Good grasp on negating Lorentz issues and ground loops.I don't think it is necessary to run a DC ground from the Copper cone. In fact the magnetron case, unless I am mistaken, is at a very high - DC potential and if it is galvanically (a fancy word that just means there is a metal to metal connection) connected to the low voltage DC ground it may create a lethal danger. More likely though it would just short out the HV output, destroying the magnetron supply faster than you can say Oh @&%$!. Even if the magnetron did not have a high potential on its case there would be no need for a DC ground. The coax or waveguide that connects the two supplies all the ground you need. Single point ground typically refers to power supplies and the single ground point would be at the power supply; in this case the low voltage DC supply (battery) that powers the distance sensor, control electronics, indicator LEDs, etc.
Thank you. I update the sketch according to your suggestions. One thing you were mistaken is that in a microwave oven, the two filament wires are actually at -5000V potential and the case of magnetron is at 0 potential. I draw a dashed line that grounds the frustum. This is because you suggested not to have it, but I suspect See-Shell has it. Anybody, other suggestions?
This is my current build that the cage can rotate 900 on my lab table. This design should be able to support even a magnetron directly on the frustum and be able to map thermal issues.
Off to bed.
Shell
Shell, I suggest you to only secure the top end of the piano wire to the frame. This ensures the piano wire is perpendicular to the earth surface at all time. If you secure the end point too, you may suffer the same symptom of NASA's new experiment, that the thermal expansion of the frustum or magnetron will shift the mass center, and when the rotation pivot is not perpendicular to the earth surface, this shift of mass center will show up as beam rotation. NASA's balance is a little bit "drooped" because of the weight of all the things mounted on the beam.
A visual might help see the captured torsional wires actions when faced with a shifting center of mass across the rotational platform. As you can see in either case it would make little difference to the platform rotation but the oscillatory actions will be greater for the single point captured wire. This action depending on the speed of the mass changes could influence measurements.
In your drawings, on the left-hand side (where the lower wire is used), your demonstration is valid, but only if the torsion pendulum's axis of rotation is exactly parallel to the gravity vector. If this (constrained) axis of rotation were not exactly parallel, then a shifting CoM would induce a false rotation as the new CoM attempted to seek the low spot in the rotation.
Thank you! I was about to explain this to Shell, but your explanation is better than my would-be one. This is one of the problems of the NASA's new test. The other is that they did not test rotation at the pivot but tested the position of the end of the beam.
The best way to hang a rotation beam is to use a single wire secured on top of the frame. The best way to test movement/rotation is to test the rotation at where the wire is. This arrangement automatically compensates for mass center problem by itself. I have carefully thought of those things and my experiment addressed those potential problems. -
#2067 by rfmwguy on 07 May, 2016 19:12
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Eddy currents in outer conductors create their own fields: https://blog.lamsimenterprises.com/tag/coaxial-cable/
If I understand this, then what you have is a mechanism where the COAX cable carries force/momentum far in excess of that of a perfectly collimated photon rocket, as is required to react the forces of the EM Drive.
If so, then how does that work?
I know very little about this type of equation. I have understood that a coaxial cable has no field outside. But, it can have magnetic field inside, is not it ?
If there is magnetic field inside the Coax, this magnetic field can give a force orders of magnitude over a photon rocket. Electric motors work with magnetic fields, and electric cars are very more efficient that photon rockets In fact, there are even far more efficient that Cannae Superconducting. -
#2068 by Tellmeagain on 07 May, 2016 19:21
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I don't think it is necessary to run a DC ground from the Copper cone. In fact the magnetron case, unless I am mistaken, is at a very high - DC potential and if it is galvanically (a fancy word that just means there is a metal to metal connection) connected to the low voltage DC ground it may create a lethal danger. More likely though it would just short out the HV output, destroying the magnetron supply faster than you can say Oh @&%$!. Even if the magnetron did not have a high potential on its case there would be no need for a DC ground. The coax or waveguide that connects the two supplies all the ground you need. Single point ground typically refers to power supplies and the single ground point would be at the power supply; in this case the low voltage DC supply (battery) that powers the distance sensor, control electronics, indicator LEDs, etc.
Thank you. I update the sketch according to your suggestions. One thing you were mistaken is that in a microwave oven, the two filament wires are actually at -5000V potential and the case of magnetron is at 0 potential. I draw a dashed line that grounds the frustum. This is because you suggested not to have it, but I suspect See-Shell has it. Anybody, other suggestions?
I stand corrected on the high potential issue. There are no DC ground loop concerns with the cone and the RF so it can just be mechanically fastened to the Aluminum beam. It doesn't make a difference if it is electrically connected or insulated from the beam. The diagram does show 3 DC wires connecting the battery to the inverter. Only 2 are needed and they should be twisted together or wired coaxially. One twist per inch with no loose loops is sufficient. I have made high current coax from Copper tubing and heavy gauge insulated wire. The impedance of this kind of coax doesn't matter with DC. What needs to be avoided here are extra ground return paths since the current that flows through that path will interact with the geomagnetic field and produce a lorentz force. Any frame connection (connections to the beam) have to be done carefully to avoid any current along the beam. There likely would not be any frame current from the magnetron supply to the inverter so both can simply be fastened to the Aluminum beam with a good electrical connection in the interest of electrical safety; without the ground wire shown in the diagram. The DC ground post on the Aluminum beam is not needed. It's safer to not have one terminal of the battery tied to the frame. No current should flow along the beam anyway.
So I updated again to reflect your suggestions. I think I have carefully read your suggestions and the drawing is accurate. Is it? Thank you！
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#2069 by Rodal on 07 May, 2016 19:25
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For those of us interested in EM Drive Developments - related to space flight applications and hence in the fact that a spacecraft in Space cannot have a coaxial cable transmitting a force to the spacecraft from the Earth., the following is of interest.
The following paper goes in detail into a calculation of the flow of momentum in a coaxial cable:
http://www.physics.princeton.edu/~mcdonald/examples/coax_momentum.pdf
Flow of Energy and Momentum in a Coaxial Cable
Kirk T. McDonald
Joseph Henry Laboratories, Princeton University, Princeton, NJ 08544
http://www.physics.princeton.edu/~mcdonald/examples/coax_momentum.pdf
Note:
* In the case of a TEM wave, for which E2 = μH2, the radial and azimuthal electric and magnetic forces cancel one another, and only the longitudinal forces remain. The only nonzero electromagnetic force in the coaxial cable is in the z direction along the longitudinal direction of the cable (this is not a thermal expansion force)
Since the terminating resistor (the EM Drive) absorbs the momentum flowing along the cable, the EM Drive experiences a force equal to the momentum flux flowing through the coaxial cable.
Thus, when using a coaxial cable, both a force and momentum are transmitted along the longitudinal direction of the coaxial cable.
The force is proportional to the electromagnetic energy density times the cross-sectional area of the coaxial cable.
Thus, once again (particularly just when Prof. Yang has nullified her previous tests using power cables, by now using batteries), showing the importance to conduct tests powered with self-integrated batteries, to prove the anomalous force in the EM Drive.
At this point in time, besides Prof. Yang, the following understand these facts:
* Cannae (new torsional pendulum with batteries)
* NASA (John Hopkins torsional pendulum with batteries)
* Hackaday Aachen Germany, tiny EM Drive team
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#2070 by Tellmeagain on 07 May, 2016 19:31
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Show me where you found out that the magnetic fields on a coaxial cable extend outside of the enclosed environment of the coax....
Very specific inputs as follows:
Glad Mr. Li is helping us here with useful suggestions. Critical, very specific inputs are what's needed for an improved test method.
1) Don't use a teeter-totter, use instead a torsional pendulum (as has been known in Aerospace R&D for 50 years of testing electromagnetic micro-thrusters), and has been known for hundreds of years since Cavendish tested big G using a torsional pendulum.
2) When testing a device that depends on radiation pressure, with forces from microNewtons to milliNewtons, use a vacuum chamber, as it has been known since the 19th century that radiation pressure tests performed in ambient conditions are subject to thermal convection artifacts, and since 1900 when Lebedev was the first person to successfully test radiation pressure. He was able to do this using a vacuum chamber. That was 116 years ago.
3) When testing a device that acts as a free-energy machine, the test must use batteries self-integrated in the moving device, as used by Yang and by Brito, Marini and Galian to nullify their previous tests conducted with power cords. Ignoring this, ignores the flow of momentum in the power cord, from the stationary source of power, as electromagnetic fields carry momentum as has been known for over a century. There is momentum being carried in a coaxial power cord: S=ExH
Shell
Shell, I think what you said is true only in an ideal world ---- If the coax outer conductor is superconductive . If it is not, there does exist magnetic field outside of the coaxial cable, especially when the cable is bent. This is not related to the DC Lorentz force I focused on, but I think I'd better speak out. You, I and Paul March should have engineer minds --- that nothing is perfect in the engineer world. For example, NASA's second generation magnetic dump, which is closed (shielded), still induced a lot of magnetic field around it. I demonstrated this in the supplemental material of the Lorentz force paper. -
#2071 by RonM on 07 May, 2016 19:33
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Eddy currents in outer conductors create their own fields: https://blog.lamsimenterprises.com/tag/coaxial-cable/
If I understand this, then what you have is a mechanism where the COAX cable carries force/momentum far in excess of that of a perfectly collimated photon rocket, as is required to react the forces of the EM Drive.
If so, then how does that work?
I know very little about this type of equation. I have understood that a coaxial cable has no field outside. But, it can have magnetic field inside, is not it ?
If there is magnetic field inside the Coax, this magnetic field can give a force orders of magnitude over a photon rocket. Electric motors work with magnetic fields, and electric cars are very more efficient that photon rockets In fact, there are even far more efficient that Cannae Superconducting.
Imperfections in the shield can cause leakage. Coaxial cables shields are usually woven copper or a metal foil. The cable should be tested.
I think it would be simpler to test the entire rig with some sort of dummy load that should not produce any thrust. Maybe a cylinder or terminating resistor instead of frustum. If any movement is measured with the dummy load it will be experimental error and can be subtracted out of the frustum test. -
#2072 by rfmwguy on 07 May, 2016 19:45
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Yes, a dummy load is absolutely the best way to test for any stray forces...however, a 1 kW, 2.4 GHz dry load is quite expensive and bulky: http://tinyurl.com/z2qxvgw
Eddy currents in outer conductors create their own fields: https://blog.lamsimenterprises.com/tag/coaxial-cable/
If I understand this, then what you have is a mechanism where the COAX cable carries force/momentum far in excess of that of a perfectly collimated photon rocket, as is required to react the forces of the EM Drive.
If so, then how does that work?
I know very little about this type of equation. I have understood that a coaxial cable has no field outside. But, it can have magnetic field inside, is not it ?
If there is magnetic field inside the Coax, this magnetic field can give a force orders of magnitude over a photon rocket. Electric motors work with magnetic fields, and electric cars are very more efficient that photon rockets In fact, there are even far more efficient that Cannae Superconducting.
Imperfections in the shield can cause leakage. Coaxial cables shields are usually woven copper or a metal foil. The cable should be tested.
I think it would be simpler to test the entire rig with some sort of dummy load that should not produce any thrust. Maybe a cylinder or terminating resistor instead of frustum. If any movement is measured with the dummy load it will be experimental error and can be subtracted out of the frustum test. -
#2073 by kml on 07 May, 2016 20:17
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I would suggest to make each experiment directed east, west, north and south, and to make theses four experiences several time at different hours in the day. Of course, the orientation, the hour, and the position should be noted.
If the anomalous force was due to a mode of interaction with other masses, this interaction may change in function of the relative speeds of the drive with other masses. So, the force may be different if it is in the direction of the rotation of the earth, or at the opposite. The force may be different if it is directed in the sense of the earth turning around the sund, or at the opposite. The force also may be different if the drive is located in the north pole, or on the equator.
This is a great suggestion. Different orientations and times of day may reveal (or not reveal) unexpected interactions. Interactions with the Earth's magnetic field, Sun/Moon gravity, solar or extra-solar neutrinos, or the Earth's peculiar motion relative to the cosmic microwave background are examples that would have directional/temporal dependency.
WELCOME BACK
Last time (it feels like a year ) if my memory is correct you were assessing current design with copper gaskets at each end to address RFI issues and you were running and collecting data. If my memory is correct your results were that a dielectric alone is not enough to produce measurable results in a cavity with constant dimensions along the length. Similar results as Zellerium (California Polytechnic State Univ., San Luis Obispo, Zeller, Kraft, Echols)
Are you ready to post your data in the EM Drive wiki ?
http://emdrive.wiki/Experimental_Results
Thanks
You are correct, I did not have any positive results before suspending my tests. I was testing a rectangular non-tapered waveguide @~1250MHz closed at both ends with various (ABS, Al2O3) dielectric media at one end. The experiment was battery powered and remote (RF) controlled. There was considerable difficulty in eliminating RFI effects on the digital scale but I had made progress on that before stopping.
I am going to take another look at the experiment and see if I can get reliable data out of it. -
#2074 by VAXHeadroom on 07 May, 2016 20:32
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Bookmark this post if you want to watch tmro.tv's discussion with me tomorrow 5 pm e.s.t. usa. Think there's a countdown timerr on it. They record so I'll post link to that in a few days. Believe I join about 25 minutes in. Anything you want me to mention, PMMe and I'll try to add your inputs. Will give a broad overview of efforts to date. Will not say much if anything about wild, speculative applications, just spaceflight related general info. If you have any breaking news, nows the time. PM me.
If you join in the show live, please create a username for the online chat. The default will be "Citizen_####" or something similar, you can type over this name to create something else. Suggest using whatever username you use on here (I do)
Hope to see a bunch of you all on there - I participate pretty much ever week and have been for about 7 years
The main website is www.tmro.tv/live -
#2075 by Tellmeagain on 07 May, 2016 20:33
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Look at the dimension,
Yes, a dummy load is absolutely the best way to test for any stray forces...however, a 1 kW, 2.4 GHz dry load is quite expensive and bulky: http://tinyurl.com/z2qxvgw
Eddy currents in outer conductors create their own fields: https://blog.lamsimenterprises.com/tag/coaxial-cable/
If I understand this, then what you have is a mechanism where the COAX cable carries force/momentum far in excess of that of a perfectly collimated photon rocket, as is required to react the forces of the EM Drive.
If so, then how does that work?
I know very little about this type of equation. I have understood that a coaxial cable has no field outside. But, it can have magnetic field inside, is not it ?
If there is magnetic field inside the Coax, this magnetic field can give a force orders of magnitude over a photon rocket. Electric motors work with magnetic fields, and electric cars are very more efficient that photon rockets In fact, there are even far more efficient that Cannae Superconducting.
Imperfections in the shield can cause leakage. Coaxial cables shields are usually woven copper or a metal foil. The cable should be tested.
I think it would be simpler to test the entire rig with some sort of dummy load that should not produce any thrust. Maybe a cylinder or terminating resistor instead of frustum. If any movement is measured with the dummy load it will be experimental error and can be subtracted out of the frustum test.
17.98" x 8.95" x 4.3" (L x W x H)
456.69 x 227.33 x 109.22 mm
Then look at the dimension of a typical frustum. Not as big, heavy, and not as hot when in operation. Now comes the challenge. Why don't we make the frustums and market them as 1KW or even 2.5KW dummy load? They should swiftly wipe the current dummy load devices out of market.
A simple fact is that the frustum does not consume 1KW at all. The force when described as mN/kW is nonsense because the frustum consumes only a few Watts or at most tens of Watts. Majority of the suppsed 1KW power is simply reflected back to the magnetron or RF amplifier. In the case of magnetron, the said 1KW RF power is simply not generated in the first place. When the frustum is operated in high Q, its microwave is almost 90 degree compared to that of the magnetron. The magnetron can only deliver a fraction of its 1kW capacity to the out-of-phase field of the frustum.
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#2076 by RotoSequence on 07 May, 2016 21:04
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A simple fact is that the frustum does not consume 1KW at all. The force when described as mN/kW is nonsense because the frustum consumes only a few Watts or at most tens of Watts. Majority of the suppsed 1KW power is simply reflected back to the magnetron or RF amplifier. In the case of magnetron, the said 1KW RF power is simply not generated in the first place. When the frustum is operated in high Q, its microwave is almost 90 degree compared to that of the magnetron. The magnetron can only deliver a fraction of its 1kW capacity to the out-of-phase field of the frustum.
If the effect is real, there's probably going to be a lot to learn from building custom magnetrons for EM driving. On the other hand, maybe there are middle-men to cut out from the cavity resonators driving an electron cloud generating an RF source driving a cavity resonator chain that comprises an EM drive experiment? -
#2077 by frobnicat on 07 May, 2016 21:31
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Sheeshell, following the Pr Yang nullification, I support Dr Rodal's advice. Compared to the time and money that you used to make your build, making it battery powered will not take you so long time. And, if it is a positive result, the comparison with the data with external power will be very interesting.
This is why I have advanced to this test stand. I'll be keeping most of the hardware and be able to change very basic items like power source, rotational versus teeter totter (rotate the stand 900), rotational acceleration and even just a thrust component.
I welcome any ideas to enhance this test bed (other than a vacuum chamber).
Shell
Not requiring a vacuum chamber : it is known that magnetic couplings have been a major factor in some of the values reported for previous experiments. Lorentz forces of explicit (known) DC components can be "mitigated" and I see this is discussed here, but this is only a best effort that has no guaranty of perfect cancellation (bends, imperfect contacts, local gradients due to ferromagnetic materials in vicinity...). And moreover it is not excluded that the RF energy itself generates significant "rectified" currents even when it shouldn't, say for instance, asymmetrical electron wind near the antennae (pure speculation, probably not) but yet if some effect persists we have to consider more surprising mechanisms, not only to explain it as a real effect (useful for space propulsion) but also to see how it could be from local coupling (not useful for space propulsion but not obvious either).
Anyway, local DC geomagnetic field, perturbed by ferromagnetic materials nearby (steel reinforced concrete, whatever...), ie. not necessarily perfectly constant in magnitude and direction in the volume of the experiment, appears as a major potential for non obvious spurious (rotational and/or linear) momentum exchange with surrounding. DC magnetic field hardly can be zeroed out. My proposition is to quantify the influence of local environmental magnetic field. For instance that you make a (crude) Helmholtz coils assembly that can encompass at least the test article, and with strong enough induced magnetic field that it can overcome in magnitude the local geomagnetic field. No need to invest into expansive gaussmeter at first, a magnetic compass would be conclusive enough that the Helmholtz coils do overcome the local field (or smart phone magnetometer app, though I'd personally prefer good old compass). Among your various experiments, take the best configuration in term of reproducibility (apparently giving cleanest signal) and record results with/without added local field, for various orientations of Helmholtz coils assembly and magnitude (current in coils), and also with only one coil at a time (higher divergence rather than "flat" volumetric field). Repeat a few time at various magnitude to extract a plot of measured force as function of forward and backward current in coils with a reasonable low noise.
Either the plots (force wrt. coils intensity for X Y Z) are strictly horizontal, ie. there is no influence of local DC magnetic field on the result, the effect (and applicability to space propulsion holds) up to magnitude characteristics of geomagnetic field. Or there is a slope, indicating the force needs (pushes on) a local field, which is bad news for space propulsion, but better to know than ignore. If this later case appears then further quantitatively precise characterisation should be done...
Maybe if Helmholtz coils prove to be too expensive in copper wiring, or too time consuming, a simple strong permanent magnet (from a dismantled speaker, whatever) strong enough to deviate a magnetic compass from a few 10s of centimeters can be used to probe possible influence on results (all other things being equal).
That would make your experiment the first (in experimented EM drive devices I think ?) to go beyond "care has been taken of local magnetic field interactions to minimize spurious couplings", to an experimentally strong characterization of this specific systematic error source, whatever the specifics, including surprising and/or improbable ones. I don't count in that league experiments where DC field has been varied but indirectly and not all other parameters being kept equal and not enough data points to assess statistical significance (shielding of the magnetic dampener at EagleWorks for instance). I would personally take that as a very important progress (before self containment and vacuum testing).
p.s.
in https://forum.nasaspaceflight.com/index.php?topic=39772.msg1529226#msg1529226 you write "I feel the strong need to do this especially if I'm seeing something above 3.33mn/KW that would violate known conservation laws.". Self-powered propellantless propulsion is in tension with conservation laws as soon as exceeding 3.33µN (micro-Newtons) not 3.33mN (milli-Newtons) per kW (kilo-Watts) of input power as sole sacrificed flow.
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#2078 by Rodal on 07 May, 2016 21:37
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Not all builds are the same. Mine, for example, has no transmission line (coax or waveguide) which will propagate the thermal forces you speak about. Yang and Dresden chose a different design parameter, we don't know yet what Shell has chosen...could be several things....
If I understand this, then what you have is a mechanism where the COAX cable carries force/momentum far in excess of that of a perfectly collimated photon rocket, as is required to react the forces of the EM Drive.
If so, then how does that work?
It works as with any experimental artifact, as with thermal expansion, thermal convection, etc. It has to do with how one calculates the anomalous (=unexplained) force, and how one calculates the power that it took to produce the anomalous force.
The unexplained force/InputPower may have been incorrectly calculated. If you ignore the electromagnetic momentum, then the "anomalous force" is incorrectly calculated: extra momentum seems to come magically. The actual force that is "anomalous" = unexplained, may be much smaller, negligible or non-existent. (*)
As to how such calculations matter, see this: http://www.physics.princeton.edu/~mcdonald/examples/feynman_cylinder.pdf
Suggestion: more effort should go into providing power with batteries self-integrated in the test, as done by Yang. Imagine how much time and effort would have been saved if Yang would have done that years ago.
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(*) Evidence of incorrect calculation of anomalous forces abounds: Yang's prior calculations, prior to using batteries.
Incorrect calculation of stresses because of using incorrect equations to calculate the stress that do not take into account the electromagnetic momentum.
I might add that we seem to be jumping rapidly from force momentum from feed lines or power leads to frustum stresses within a few posts...not having resolved either one.
Simply stated, someone should model, with real numbers, the (micro or milli) Newton force of both lines and the cavity itself in a torsional test setup. Anything less is simply not as useful IMO.
1) Your statement incorrectly states that I was referring to thermal forces, while it is plain to see that I was referring to electromagnetic forces.
2) The following paper analyzes the longitudinal electromagnetic force in a coaxial cable that I was referring to: http://forum.nasaspaceflight.com/index.php?topic=39772.msg1530785#msg1530785 . Electromagnetic fields carry momentum. Is that surprising? The force is proportional to the electromagnetic energy density times the cross-sectional area of the coaxial cable.
3)Quote from: GilbertDriveIt is like if I was wanting to prove telekinesis powers, by making move a spoon that is attached to my finger by a cord. Even if I try to convince the spectators that the cord can not help, that I am not using it to make move the spoon, they will tell me "And why not without the cord ?"
It is worse than that: since when somebody dares to ask, "how does that relate to Space Flight applications since in space you cannot use a cord" the answer is: because I say that my cord does not carry any force that can move the spoon, and otherwise prove me wrong. Thus the responsibility for proving that the cord is not moving the spoon is shifted to the shoulders of the spectators, who are asked to prove otherwise, rather than the responsibility for proving so being on the shoulders of the one with the spoon and the cord
. Yes, a good analogy, because it looks like we are asked to be a docile audience, being asked to ignore the cord, while skeptical remarks are met defensively and unwelcome.
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#2079 by Monomorphic on 07 May, 2016 21:51
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Dave on TMRO Live 9.16.
In fact, there are even far more efficient that Cannae Superconducting.
. Yes, a good analogy, because it looks like we are asked to be a docile audience, being asked to ignore the cord, while skeptical remarks are met defensively and unwelcome.