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#740 by TheTraveller on 19 Dec, 2016 14:11
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Decided the 1st thruster to be replicated is the EW unit but without a dielectric. Will be excited in TE012 mode (it is too short for TE013) via a 1/4 wave stub antenna placed 1/4 guide wavelength away from the big end.
TE012 in the EW frustum without dialectric is 2.17895Ghz. So you won't be able to use a narrow band 2.4Ghz amp. Will need to be a new amp build or wideband. I did not notice any other modes particularly close to cause a problem. I didn't run a full S11, but my guess is a 1/4 lambda stub (3.44cm) is likely to be very over coupled.
The NASA frustum will resonate at TE013. I'm looking for that frequency now. It will be somewhere over 2.8Ghz.
Jamie,
Thanks for the TE013 data. May try that after the TE012 tests are completed.
Have a 100W wide band Rf amp pulled out of the shipping container and on a plane tomorrow. So should be able to handle just about any freq.
While FEKO may be good to plot standing waves, I have yet to trust it with antenna inside the cavity. BTW the stub is length adjustable & it's orientation to the side wall is also adjustable. Old hams & old EEs tune antenna by cut, bend & try. Really don't want to use a 3 stub tuner as then the KISS build gets complex.
I'll be very happy with a VSWR of 1.5:1 or lower. -
#741 by TheTraveller on 19 Dec, 2016 14:15
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calculated natural frequency (FEKO BEM analysis by Monomorphic): 2.17895Ghz
I'm simulating the 1/4 stub antenna (3.44cm), which is also 2mm in diameter. This volume of the antenna is enough to drive the frequency higher. I also didn't run an interpolation sweep, so I can refine the FEKO solution even more if I do so, since there are more simulated frequencies. This was a quick and dirty sim. Nice to know I can get that close with very little effort.
Jamie,
2mm dia is way too thick. Take a piece of 16 gauge copper wire, pull it to straighten & harden it, then cut to length and solder into the cup of the SMA connector. -
#742 by WarpTech on 19 Dec, 2016 14:49
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You just left off the gradient of the electric potential in your formula for E. This term matters, because in general there are surface charges on the walls of the cavity that can't just be ignored. If you are restricting your analysis to specific modes, you need to be stating that explicitly as a major assumption. Now that you have clarified your definition of magnetic flux a little, I can point out that you are using magnetic flux where I would expect to see electric potential in the second equation in your line defining the Lorentz gauge.
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There are several steps of your derivation that don't make sense to me before I can discuss this properly. I only mentioned it so that you can get a jump on reworking that part of your derivation as needed.
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You still haven't answered what mass/charge ratio Omega^2 is supposed to represent. You kind of implied in this post that it should be that of an electron, but you have also defined it as the time derivative of the magnetic flux which is not constant in space or time. This is the kind of problem you run into when you conflate a variable as representing what its units are.
In a TE mode, there is no free charge that contributes to the E field. There is in a TM mode, but not in a TE mode.
Regarding charge to mass ratio, I am not referring to the electron. I'm referring to the equivalent mass of the energy, stored as magnetic flux. For instance, a photon is massless, yet it has energy that interacts with gravity.
E = h*f
It has an "equivalent mass" of m = h*f/c2
There is nothing wrong with expressing energy as a mass. IMO, they are completely interchangeable, one "IS" the other, gravitationally. They differ only by a constant in flat space-time. You seem to want mass to be something "solid". Sorry, gravity doesn't care if it's solid or made up of photons, it still has an "equivalent" mass.
In the case of a mass on a spring vs an RLC oscillator. The inductance "L" is equivalent to the mass "M" on the spring. Inductance is by definition "a tube of magnetic flux". So it seems perfectly natural to me to express the energy stored as flux as an equivalent mass. You may not like it, but it is a fact.
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#743 by meberbs on 19 Dec, 2016 15:09
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So is your analysis only applicable to specific modes? Please be specific what restrictions you are working under. If so, it seems strange that you think you can then apply your results in situations completely outside your original assumptions, such as heating with no RF in the cavity....
You just left off the gradient of the electric potential in your formula for E. This term matters, because in general there are surface charges on the walls of the cavity that can't just be ignored. If you are restricting your analysis to specific modes, you need to be stating that explicitly as a major assumption. Now that you have clarified your definition of magnetic flux a little, I can point out that you are using magnetic flux where I would expect to see electric potential in the second equation in your line defining the Lorentz gauge.
...
There are several steps of your derivation that don't make sense to me before I can discuss this properly. I only mentioned it so that you can get a jump on reworking that part of your derivation as needed.
...
You still haven't answered what mass/charge ratio Omega^2 is supposed to represent. You kind of implied in this post that it should be that of an electron, but you have also defined it as the time derivative of the magnetic flux which is not constant in space or time. This is the kind of problem you run into when you conflate a variable as representing what its units are.
In a TE mode, there is no free charge that contributes to the E field. There is in a TM mode, but not in a TE mode.
Regarding charge to mass ratio, I am not referring to the electron. I'm referring to the equivalent mass of the energy, stored as magnetic flux. For instance, a photon is massless, yet it has energy that interacts with gravity.
E = h*f
It has an "equivalent mass" of m = h*f/c2
There is nothing wrong with expressing energy as a mass. IMO, they are completely interchangeable, one "IS" the other, gravitationally. They differ only by a constant in flat space-time. You seem to want mass to be something "solid". Sorry, gravity doesn't care if it's solid or made up of photons, it still has an "equivalent" mass.
In the case of a mass on a spring vs an RLC oscillator. The inductance "L" is equivalent to the mass "M" on the spring. Inductance is by definition "a tube of magnetic flux". So it seems perfectly natural to me to express the energy stored as flux as an equivalent mass. You may not like it, but it is a fact.
The energy-mass equivalence is pretty much fine, but that still doesn't explain the charge part of the mass-charge ratio. Also If you are saying this is the energy stored in a current in the walls of the cavity, please define where this current is specifically (a diagram would help, I think someone may have done some modelling of surface currents somewhere in these threads)
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#744 by TheTraveller on 19 Dec, 2016 15:19
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calculated natural frequency (FEKO BEM analysis by Monomorphic): 2.17895Ghz
Ah now I remember the TE012 resonance issue.
It is below the small end cutoff rule of thumb Roger shared being:
Min freq = c / (0.82 * small end diameter in meters): 2.3022GHz for a 0.1588 dia small end cap.
Was told if I build below that diameter limit, the analysis packages & VNA scans may show resonant modes but they will not generate much force. Maybe a little but not the force that the thrust equation predicts. In fact if you use the SPR Df equation on the EW thruster in TE012 mode it will product a non valid result.
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#745 by Rodal on 19 Dec, 2016 15:39
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Yes, you remember correctly, this is the case of a TE012 resonance for a CLOSED microwave cavity being below the cut-off frequency for an OPEN waveguide, and thus contravening Shawyer's cut-off rule for closed truncated conical cavities.calculated natural frequency (FEKO BEM analysis by Monomorphic): 2.17895Ghz
Ah now I remember the TE012 resonance issue.
It is below the small end cutoff rule of thumb Roger shared being:
Min freq = c / (0.82 * small end diameter in meters)
Was told if I build below that diameter limit, the analysis packages & VNA scans may show resonant modes but they will not generate much force. Maybe a little but not the force that the thrust equation predicts. In fact if you use the SPR Df equation on the EW thruster in TE012 mode it will product a non valid result.
Also, this is the case where you had posted (threads ago) that the resonance according to your Excel spreadsheet was not at the same frequency as the one reported by NASA, but at a significantly higher frequency.
Now we have agreement (within 0.5% or less of the calculated and experimental frequencies) between all of these:
*Monomorphic FEKO BEM analysis
*NASA's COMSOL FEA analysis
*X_Ray's analysis
*my exact eigensolution (using Wolfram Mathematica)
*NASA's reported experimental resonant frequency
and your previously reported higher calculated frequency using your Excel spreadsheet (which you said agrees with Shawyer's calculations) is now an outlier compared to the above experimental, FEM (COMSOL), BEM (FEKO) and exact solutions.
If indeed your Excel spreadsheet frequency calculation agrees with Shawyer's calculations, this means that Shawyer's frequency calculations result in calculated natural frequency for this case significantly higher than the above NASA-reported-experimental, NASA-reported-FEM (COMSOL), Monomorphic-reported-BEM (FEKO), X_Ray's solution and my-reported-exact solutions.
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#746 by TheTraveller on 19 Dec, 2016 15:47
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and your previously reported higher calculated frequency using your Excel spreadsheet is now an outlier compared to the above experimental, FEM (COMSOL), BEM (FEKO) and exact solutions.
Roger's rule of thumb is a simple to use equation which suggests the lower limit that will see the EmDrive deliver a force as predicted by the SPR equation.
My spreadsheet still works fine, just as it is based on the Df equation,, it can't predict the resonance below Df cutoff, which I have normally have no interest chasing.
But so what if you can? Operating at that freq is a really good way to only generate a few snow flakes of force, as we have seen. It also says that while COMSOL, FEKO and other methods may indicate resonance, there will be no force generated.
I will now explore this and do the 1st build and test based on the reported TE012 resonance and see if there is any force generated. Then repeat for TE013 and compare the forces generated.
Should be interesting to test if Roger's cutoff rule of thumb is correct or not.
Will also be interesting to measure the radiation pressure on the individual end plates and on the cone. TE012/TE013 allows that privilege as there are no eddy currents crossing from the end plates to the side walls, so there can be a very small physical air gap and not effect Q too much. -
#747 by Rodal on 19 Dec, 2016 15:53
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and your previously reported higher calculated frequency using your Excel spreadsheet is now an outlier compared to the above experimental, FEM (COMSOL), BEM (FEKO) and exact solutions.
Roger's rule of thumb is a simple to use equation which suggests the lower limit that will see the EmDrive deliver a force as predicted by the SPR equation.
My spreadsheet still works fine, just as it is based on the Df equation,, it can't predict the resonance below Df cutoff, which I have normally have no interest chasing.
But so what if you can? Operating at that freq is a really good way to only generate a few snow flakes of force, as we have seen. It also says the while COMSOL, FEKO and other methods may indicate resonance, there will be no force generated.
I will now explore this and do the 1st build and test based on the reported TE012 resonance and see if there is any force generated. Then repeat for TE013 and compare the forces generated.
Should be interesting to test if Roger's cutoff rule of thumb is correct or not.
TO Paul March:
So, now that you are back posting at NSF, it would be interesting to know, what is your analysis as to the reason why the NASA 2014 report authored by Brady et.al. reported that TE012 without the dielectric exhibited "no signficant thrust" at 2.168 GHz: was it because the resonant frequency was below Shawyer's cut-off guideline based on OPEN waveguides? -
#748 by Rodal on 19 Dec, 2016 16:16
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Let's have Paul address this by himself. If his understanding is now that there was a force measured, then this contravenes Shawyer's strange rule about cut-off.
Technically speaking, it is known that the cut-off rule that Shawyer is quoting only applies to constant-cross-section, OPEN waveguides. The EM Drive is not an open waveguide it is a closed cavity. The EM Drive is not a cylinder with constant cross-section, it is a truncated cone. No such rule applies to resonance of closed cavities. This was well known for several decades, since before World War II.
Schellkunoff at Bell Labs in the 1930's:
It is strange that Shawyer treats the closed cavity as it would be an open waveguide.
Shawyer also repeatedly quotes Cullen, but Cullen's experiment involved an OPEN waveguide, instead of a closed truncated conical cavity. (One of Cullen's waveguide had a constant rectangular cross-section and another waveguide had a constant circular cross-section.) (*)
Since there is resonance, then one would think that perhaps Shawyer had discovered something to do with the force not being present below cutoff. Fine, this would be an interesting insight by Mr. Shawyer.
But if there is a force below cutoff, what are we left with of Shawyer's cut-off rule? What really happens as the truncated cone is continued towards the apex of the cone? Has anyone else ever conducted such an experiment?
ATTACHMENT: My old report on resonance of microwave cavities below the cut-off rule of Shawyer
(*) REVIEW OF A.L. Cullen's "Absolute Power Measurement at Microwave Frequencies" IN REFERENCE TO EM DRIVE https://forum.nasaspaceflight.com/index.php?topic=36313.msg1369861#msg1369861
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#749 by WarpTech on 19 Dec, 2016 18:02
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In a TE mode, there is no free charge that contributes to the E field. There is in a TM mode, but not in a TE mode.
So is your analysis only applicable to specific modes? Please be specific what restrictions you are working under. If so, it seems strange that you think you can then apply your results in situations completely outside your original assumptions, such as heating with no RF in the cavity.
Regarding charge to mass ratio, I am not referring to the electron. I'm referring to the equivalent mass of the energy, stored as magnetic flux. For instance, a photon is massless, yet it has energy that interacts with gravity.
E = h*f
It has an "equivalent mass" of m = h*f/c2
There is nothing wrong with expressing energy as a mass. IMO, they are completely interchangeable, one "IS" the other, gravitationally. They differ only by a constant in flat space-time. You seem to want mass to be something "solid". Sorry, gravity doesn't care if it's solid or made up of photons, it still has an "equivalent" mass.
In the case of a mass on a spring vs an RLC oscillator. The inductance "L" is equivalent to the mass "M" on the spring. Inductance is by definition "a tube of magnetic flux". So it seems perfectly natural to me to express the energy stored as flux as an equivalent mass. You may not like it, but it is a fact.
The energy-mass equivalence is pretty much fine, but that still doesn't explain the charge part of the mass-charge ratio. Also If you are saying this is the energy stored in a current in the walls of the cavity, please define where this current is specifically (a diagram would help, I think someone may have done some modelling of surface currents somewhere in these threads)
The coupling constant, sqrt(4*pi*G*e0) has units of Charge to Mass. It is interpreted as the ratio of the Planck Mass with the Planck Charge.
Mp = sqrt(hbar*c/G)
Qp = sqrt(4*pi*e0*hbar*c)
We can't physically observe the Planck mass or the Planck charge, but we can measure the fine structure constant that depends on the (Electric charge over the Planck charge)2, and we can measure G/c2 which is the Planck length over the Planck mass. To me, this is something you should already know if you understand dimensional analysis. The charge in the Omega2 term comes the fact that Volts are Joules/Coulomb. Nothing more. Asking what the charge part is is like asking what Voltage is. You simply do not see the implied connections between units and physical parameters as clearly as I do.
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#750 by Bob012345 on 19 Dec, 2016 18:07
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In a TE mode, there is no free charge that contributes to the E field. There is in a TM mode, but not in a TE mode.
So is your analysis only applicable to specific modes? Please be specific what restrictions you are working under. If so, it seems strange that you think you can then apply your results in situations completely outside your original assumptions, such as heating with no RF in the cavity.
Regarding charge to mass ratio, I am not referring to the electron. I'm referring to the equivalent mass of the energy, stored as magnetic flux. For instance, a photon is massless, yet it has energy that interacts with gravity.
E = h*f
It has an "equivalent mass" of m = h*f/c2
There is nothing wrong with expressing energy as a mass. IMO, they are completely interchangeable, one "IS" the other, gravitationally. They differ only by a constant in flat space-time. You seem to want mass to be something "solid". Sorry, gravity doesn't care if it's solid or made up of photons, it still has an "equivalent" mass.
In the case of a mass on a spring vs an RLC oscillator. The inductance "L" is equivalent to the mass "M" on the spring. Inductance is by definition "a tube of magnetic flux". So it seems perfectly natural to me to express the energy stored as flux as an equivalent mass. You may not like it, but it is a fact.
The energy-mass equivalence is pretty much fine, but that still doesn't explain the charge part of the mass-charge ratio. Also If you are saying this is the energy stored in a current in the walls of the cavity, please define where this current is specifically (a diagram would help, I think someone may have done some modelling of surface currents somewhere in these threads)
The coupling constant, sqrt(4*pi*G*e0) has units of Charge to Mass. It is interpreted as the ratio of the Planck Mass with the Planck Charge.
Mp = sqrt(hbar*c/G)
Qp = sqrt(4*pi*e0*hbar*c)
We can't physically observe the Planck mass or the Planck charge, but we can measure the fine structure constant that depends on the (Electric charge over the Planck charge)2, and we can measure G/c2 which is the Planck length over the Planck mass. To me, this is something you should already know if you understand dimensional analysis. The charge in the Omega2 term comes the fact that Volts are Joules/Coulomb. Nothing more. Asking what the charge part is is like asking what Voltage is. You simply do not see the implied connections between units and physical parameters as clearly as I do.
A particle with the Plank mass would be so large as to be almost visible. It's about 22 micrograms. -
#751 by WarpTech on 19 Dec, 2016 18:17
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A particle with the Plank mass would be so large as to be almost visible. It's about 22 micrograms.
Not with a size of 1.6 x 10-35 m! It's a long way from visible. -
#752 by as58 on 19 Dec, 2016 18:38
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We can't physically observe the Planck mass or the Planck charge, but we can measure the fine structure constant that depends on the (Electric charge over the Planck charge)2, and we can measure G/c2 which is the Planck length over the Planck mass. To me, this is something you should already know if you understand dimensional analysis. The charge in the Omega2 term comes the fact that Volts are Joules/Coulomb. Nothing more. Asking what the charge part is is like asking what Voltage is. You simply do not see the implied connections between units and physical parameters as clearly as I do.
I still have no idea what Omega^2 means. It is the inverse charge-to-mass ratio (does that mean just mass-to-charge ratio?), but of what? Is there more to it than just dimensional analysis? And why does integrating it with respect to time give magnetic flux? Through what surface? In case of constant non-zero Omega (or is such a case not possible? if so, why?), don't your equations imply that the magnetic flux just keeps growing without bound?
Once again the discussion seems to be going around in circles. -
#753 by Bob012345 on 19 Dec, 2016 18:49
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A particle with the Plank mass would be so large as to be almost visible. It's about 22 micrograms.
Not with a size of 1.6 x 10-35 m! It's a long way from visible.
You must be assuming a particle with the Plank mass also has the Plank Length. I wasn't assuming that because there is no such think as a Plank particle anyway. -
#754 by supersubie on 19 Dec, 2016 18:52
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What happened to the DIYers experiments who was building a trapeze shaped thruster in his garage? He looked like he was building some pretty solid bits of EM drive related testing kit and I was hoping we would hear more from him on the latest design. I cant for the life of me remember his posting name but if any of you know it would be great to hear what happened to him! Maybe I missed his posts on stopping his tests?
On that note:
What happened to Shell? She got a nice chunk of funding on her Gofundme page and then went dark after saying she seemed to have found something in January earlier this year. Would be great to have a status update Shell and a timeline on potential data release. ( I have been waiting with baited breath for nearly 12 months now haha!!)
Also The Traveler, You keep saying that you have a lot of kit in construction or in shipping, but never any proof of that being a reality. I have wanted to believe you claims of having done all of this but its getting a bit beyond credible now after such a long time with no pictures of anything of merit. To silence your critics on the other forums why don't you upload a scanned receipt of shipping / construction of your drives? You've paid for it all surely so you must have that information to hand that you could show. I think for yourself that would be an easy way to gain some credibility behind your reported time frames
I think you guys are all doing awesome work on these forums and I don't mean to sounds moany, just with all of the recent news from NASA and now seemingly China I am keen to she where we are at with the DIY experiments! -
#755 by Rodal on 19 Dec, 2016 18:59
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It is a great achievement for this forum to have now this universal agreement:
COMPARISON OF SOLUTIONS WITH NASA's experiment
measured frequency at which NASA test was performed: 2.168 GHz
calculated natural frequency (Rodal exact solution, assuming spherical ends): 2.129 GHz
calculated natural frequency (Rodal exact solution, assuming flat ends): 2.165 GHz
calculated natural frequency (analysis by X_Ray method A): 2.16512 GHz
calculated natural frequency (analysis by X_Ray method B): 2.1653438 GHz
calculated natural frequency (COMSOL FEA analysis by Frank Davis at NASA): 2.179 GHz
calculated natural frequency (FEKO BEM analysis by Monomorphic): 2.17895Ghz
calculated natural frequency (Keysight EMPro FEA analysis by X_Ray): 2.17983GHz
Just a relatively short time ago someone was posting that TE012 could not have resonated at this 2.168 GHz frequency, because it was below cut-off for an open waveguide.
The important thing is that now it has been completely confirmed that:
1) The natural frequency response of the EM Drive is 100% completely classical, the natural frequency response can be fully calculated by Maxwell's equations
2) The exact solution (as shown by Greg Egan), Finite Element and Boundary element methods can very accurately calculate the eigenvalues for the EM Drive.
There is no New Physics discernable at all concerning the natural frequency response.
There is no "cut-off" that prevents resonance at the classical natural frequency for a truncated cone.
Anyone coming up with any New Physics explanation for any EM Drive effect has to simultaneously show that the natural frequency completely obeys classical (Maxwell's equations) methods, and should address why the natural frequency is not affected by such New Physics.
For example, if one claims new inertial effects, if there is "New Physics Inertial Mass not accounted for by classical physics" why isn't such inertial mass affecting the natural frequency?
One has to show that the effect on classical natural frequency is negligible, yet the effect on classical conservation of momentum is not negligible. -
#756 by WarpTech on 19 Dec, 2016 20:13
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We can't physically observe the Planck mass or the Planck charge, but we can measure the fine structure constant that depends on the (Electric charge over the Planck charge)2, and we can measure G/c2 which is the Planck length over the Planck mass. To me, this is something you should already know if you understand dimensional analysis. The charge in the Omega2 term comes the fact that Volts are Joules/Coulomb. Nothing more. Asking what the charge part is is like asking what Voltage is. You simply do not see the implied connections between units and physical parameters as clearly as I do.
I still have no idea what Omega^2 means. It is the inverse charge-to-mass ratio (does that mean just mass-to-charge ratio?), but of what? Is there more to it than just dimensional analysis? And why does integrating it with respect to time give magnetic flux? Through what surface? In case of constant non-zero Omega (or is such a case not possible? if so, why?), don't your equations imply that the magnetic flux just keeps growing without bound?
Once again the discussion seems to be going around in circles.
Here is an update with no more offensive Omega's. This is text book Maxwell's equations in the Lorentz gauge. The Area is defined as the cross section of the frustum, so that current and electric field are circles around the z-axis. Magnetic flux passes through these surfaces. There are no DC variables here, the frequency is assumed to be near 2.4 GHz for the EmDrive, so the flux can't "keep growing", it oscillates with the resonant frequency. The mode is assumed to be a TE01x mode, where there is no free charge on the surface of the frustum.
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#757 by rfmwguy on 19 Dec, 2016 22:04
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What happened to the DIYers experiments who was building a trapeze shaped thruster in his garage? He looked like he was building some pretty solid bits of EM drive related testing kit and I was hoping we would hear more from him on the latest design. I cant for the life of me remember his posting name but if any of you know it would be great to hear what happened to him! Maybe I missed his posts on stopping his tests?
Enjoy some of my 38 EmDrive DIY videos:
On that note:
What happened to Shell? She got a nice chunk of funding on her Gofundme page and then went dark after saying she seemed to have found something in January earlier this year. Would be great to have a status update Shell and a timeline on potential data release. ( I have been waiting with baited breath for nearly 12 months now haha!!)
Also The Traveler, You keep saying that you have a lot of kit in construction or in shipping, but never any proof of that being a reality. I have wanted to believe you claims of having done all of this but its getting a bit beyond credible now after such a long time with no pictures of anything of merit. To silence your critics on the other forums why don't you upload a scanned receipt of shipping / construction of your drives? You've paid for it all surely so you must have that information to hand that you could show. I think for yourself that would be an easy way to gain some credibility behind your reported time frames
I think you guys are all doing awesome work on these forums and I don't mean to sounds moany, just with all of the recent news from NASA and now seemingly China I am keen to she where we are at with the DIY experiments!
https://www.youtube.com/channel/UCm54FS3u2aDeutnMsV0cITg/videos -
#758 by Monomorphic on 19 Dec, 2016 22:23
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What happened to the DIYers experiments who was building a trapeze shaped thruster in his garage? He looked like he was building some pretty solid bits of EM drive related testing kit and I was hoping we would hear more from him on the latest design. I cant for the life of me remember his posting name but if any of you know it would be great to hear what happened to him! Maybe I missed his posts on stopping his tests?
This is me!
I temporarily suspended testing after giving up on trying to use a commercial magnetron as the RF source. There are just too many drawbacks - namely frequency drift due to thermal runaway because of cooling issues, as well as vortex shedding from the heatsink and thermal heating of the power leads. In short, I could not achieve resonance using a cheap microwave magnetron.
My test stand is still ready to go, but I am switching to a battery powered solid state RF source, which is vastly more expensive, and a professionally forged/machined copper cavity. Most recently, I have been using computational electromagnetics to design an ideal TE013 cavity that I hope to have fabricated early next year. You can see some of that progress on my youtube channel. Future updates will also be posted here on NSF: https://www.youtube.com/user/monomorph1/videos
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#759 by rfmwguy on 20 Dec, 2016 00:13
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I totally spaced the reference to Trapezoidal as being yours, otherwise I would have linked to your utube channel. Sorry about that!What happened to the DIYers experiments who was building a trapeze shaped thruster in his garage? He looked like he was building some pretty solid bits of EM drive related testing kit and I was hoping we would hear more from him on the latest design. I cant for the life of me remember his posting name but if any of you know it would be great to hear what happened to him! Maybe I missed his posts on stopping his tests?
This is me! I temporarily suspended testing after giving up on trying to use a commercial magnetron as the RF source. There are just too many drawbacks - namely frequency drift due to thermal runaway because of cooling issues, as well as vortex shedding from the heatsink and thermal heating of the power leads. In short, I could not achieve resonance using a cheap microwave magnetron.
My test stand is still ready to go, but I am switching to a battery powered solid state RF source, which is vastly more expensive, and a professionally forged/machined copper cavity. Most recently, I have been using computational electromagnetics to design an ideal TE013 cavity that I hope to have fabricated early next year. You can see some of that progress on my youtube channel. Future updates will also be posted here on NSF: https://www.youtube.com/user/monomorph1/videos
I temporarily suspended testing after giving up on trying to use a commercial magnetron as the RF source. There are just too many drawbacks - namely frequency drift due to thermal runaway because of cooling issues, as well as vortex shedding from the heatsink and thermal heating of the power leads. In short, I could not achieve resonance using a cheap microwave magnetron.