Like most here I'm fascinated and intrigued. However, I'm terrible at this type of math and better at making things. The device seems kind of simple on the surface, but I must assume I'm missing something (many things).Have any science hobbyists built their own machine yet? I can't imagine that only three people have done this so far, and I'm working with a peer to design our own and build it this summer. I'm still reading and re-reading this thread, and I'm not too many pages into it. So if someone has posted their experiments I'm sure I'll run across them sooner or later, but if anyone knows of any build logs or hobbyists making a drive I'd love to see what they did and how it worked.I do have a question for those who may know, what do you think is the biggest hurdle to building a functioning EM Drive?
...I do have a question for those who may know, what do you think is the biggest hurdle to building a functioning EM Drive?
Quote from: zlspradlin on 05/06/2015 03:41 pmLike most here I'm fascinated and intrigued. However, I'm terrible at this type of math and better at making things. The device seems kind of simple on the surface, but I must assume I'm missing something (many things).Have any science hobbyists built their own machine yet? I can't imagine that only three people have done this so far, and I'm working with a peer to design our own and build it this summer. I'm still reading and re-reading this thread, and I'm not too many pages into it. So if someone has posted their experiments I'm sure I'll run across them sooner or later, but if anyone knows of any build logs or hobbyists making a drive I'd love to see what they did and how it worked.I do have a question for those who may know, what do you think is the biggest hurdle to building a functioning EM Drive? How about some open source design? openscad has been mentioned before. We could put the STL files on the wiki.
Quote from: zlspradlin on 05/06/2015 03:41 pm...I do have a question for those who may know, what do you think is the biggest hurdle to building a functioning EM Drive?Funding.
...DO NOT reinvent the wheel.Follow Shawyer as close as you can.Plenty of clues but you need to do a lot of reading.....
Quote from: TheTraveller on 05/06/2015 04:01 pm...DO NOT reinvent the wheel.Follow Shawyer as close as you can.Plenty of clues but you need to do a lot of reading.....You are writing that in reference to Shaywer's experiments, I presume, but a number of Shawyer's prescriptions are tied to his theoretical model. I read the paper that Shawyer sent to Mulletron, to support Shawyer's theoretical model.I wrote a review of this paper here: http://forum.nasaspaceflight.com/index.php?topic=36313.msg1369861#msg1369861Showing that there is nothing in that paper (by Cullen) supporting Shawyer's theoretical model. On the contrary, it follows the same Maxwell's equations and laws followed by Greg Egan http://gregegan.customer.netspace.net.au/SCIENCE/Cavity/Cavity.html who concludes that the EM Drive should have no thrust force.Did Shawyer send the paper by Cullen by mistake, and he meant to send another paper instead to support his theory?Do you know of any paper supporting Shawyer's theoretical model ?
Quote from: Rodal on 05/06/2015 04:11 pmQuote from: TheTraveller on 05/06/2015 04:01 pm...DO NOT reinvent the wheel.Follow Shawyer as close as you can.Plenty of clues but you need to do a lot of reading.....You are writing that in reference to Shaywer's experiments, I presume, but a number of Shawyer's prescriptions are tied to his theoretical model. I read the paper that Shawyer sent to Mulletron, to support Shawyer's theoretical model.I wrote a review of this paper here: http://forum.nasaspaceflight.com/index.php?topic=36313.msg1369861#msg1369861Showing that there is nothing in that paper (by Cullen) supporting Shawyer's theoretical model. On the contrary, it follows the same Maxwell's equations and laws followed by Greg Egan http://gregegan.customer.netspace.net.au/SCIENCE/Cavity/Cavity.html who concludes that the EM Drive should have no thrust force.I'm an engineer that designs, builds, commissions & teaches others how to maintain what I designed and built, while being very willing to pick up a tool bag and get grease up to my arm pits to get things back working and into service. I look at tests of stuff that are claimed to work. If they pass my gut test, I may used them to guide my replication and test process. I try to limit reinventing the wheel.Everything I read from Shawyer about how the devices interact with / work in the physical world, supports his many & various claims & statements & builds a strong model that they do indeed work.To settle the matter if the EM Drive works or not, for me, demands that I do a replication, as close to the work Shawyer has done as possible. Which is what I'm planning to do.
Quote from: TheTraveller on 05/06/2015 04:01 pm...DO NOT reinvent the wheel.Follow Shawyer as close as you can.Plenty of clues but you need to do a lot of reading.....You are writing that in reference to Shaywer's experiments, I presume, but a number of Shawyer's prescriptions are tied to his theoretical model. I read the paper that Shawyer sent to Mulletron, to support Shawyer's theoretical model.I wrote a review of this paper here: http://forum.nasaspaceflight.com/index.php?topic=36313.msg1369861#msg1369861Showing that there is nothing in that paper (by Cullen) supporting Shawyer's theoretical model. On the contrary, it follows the same Maxwell's equations and laws followed by Greg Egan http://gregegan.customer.netspace.net.au/SCIENCE/Cavity/Cavity.html who concludes that the EM Drive should have no thrust force.
OK, here is one practical thing that researchers can adopt, based on Cullen's paper (and 140 years since Maxwell, with people trying to perform experimental measurements of radiation pressure, which are plagued by air convection currents), to avoid getting false data:It was impossible to obtain a stable baseline, even on a relatively short-term basis of a minute's duration. This continual drifting of the baseline was found to be due to air convection currents set up by small and changing temperature gradients within the microwave waveguides. The remedy was to reduce the air resistance of the reflecting end plate so that the convection currents would have no appreciable effect. The reflecting end plate was replaced by a system of concentric wire rings (shown on Fig. 12 of Cullen's paper). The rings acted as an almost perfect reflector of the electromagnetic waves but at the same time had a small effective cross-section to air currents. NASA, Shawyer, Yang, and other EM Drive researchers would be well advised to experiment with replacing the end plates of the EM Drive with this system of concentric rings, in order to address the problem of air convection currents that has plagued radiation pressure experiments in ambient conditions ever since Maxwell 140 years ago.
Quote from: Rodal on 05/05/2015 02:08 pm.....Please see the following reference (https://www.osapublishing.org/oe/fulltext.cfm?uri=oe-17-1-34&id=175583, click "Get PDF" to download the paper for free):It is shown that all modes run continuously from travelling waves through a transition to an evanescent (exponentially decaying) wave region and the value of the attenuation increases as they approach the cone vertex. A strict distinction between pure travelling waves and pure evanescent (exponentially decaying) waves cannot be achieved for conical waveguide. One mode after the other reaches cutoff in the tapered hollow metallic waveguide as they approach the cone vertex......Thank you Dr. Rodal for a very informative post!I've been studying the reference you provided, to Zeng and Fan. You cannot imagine how coincidental it is, but sometimes the universe works that way. Their equations 8 thru 11, are simple enough to understand without too much difficulty. These are "effectively" the same equations that govern gravity in the Engineering model of GR I work with, which is based on the PV Model. Gravity, as a refractive index, appears as the Damping function that governs the attenuation of the wave functions, and the ZPF acts as the Driving function that keeps it all afloat at "our" relative vacuum energy level. The two are in equilibrium, in what QED calls the fluctuation-dissipation relationship, and gravity is the asymmetry between the two that occurs wherever you have matter that filters the modes. It's pretty simple and intuitive to understand, but nobody seems to get it.You asked about the truncated cones. From an engineering perspective, if it is not truncated it will have a difficult time resonating at any mode. The convex-concave end plates would seem to be necessary to maximize energy storage as spherical harmonics. So then, what modes do we want to attenuate? That would depend on what modes we can inject that will sustain resonance. It won't resonate when the angle is increased too much, but if we have attenuation factor equations from this paper, then I believe it can be modeled. Getting back to the paper, based on their graphs for attenuation, it would seem a small angle is preferred. A large angle approximates a flat plate. Anything greater than pi/6 is not much better than bouncing photons off of a flat plate. However, for theta = pi/24, the attenuation is very high at much shorter wavelengths, and very high at longer wavelengths. It needs to strike a balance between energy storage and thrust at the modes available to us.Again, gravity acts on the wave functions through the metric, transforming the (E,p) 4-vector. The metric is a refractive index. The effect on the wave function is equivalent to a Damping factor, in the damped harmonic oscillator equation. I see the attenuation factor in their plots as "similar" to that effect, acting on the microwaves in the cavity near the cut-offs. As the waves are attenuated, their momentum is absorbed as wave velocity goes to zero, just like light falling into a black hole. The result is propulsion. The bonus is that in such a space-time where the speed of light is variable, momentum conservation is dependent on the group velocity. It's not Newtonian anymore, because velocity is not a constant.The light is being squeezed by the slowing of the group velocity, and since Energy is conserved, momentum must increase to compensate for reduced wave velocity. Another way to look at it is, photons in the waveguide "gain" an "effective mass". I see a lot of people arguing over photon rockets, despite the evidence that the thrust is orders of magnitude larger. No rocket nozzle is going to change that as long as the speed of light is considered to be constant, even if it captured all the energy from all the reflections produced. In order to get the thrust values they are seeing you must consider the reduction in wave velocity inside the waveguide, and that attenuation is asymmetrical, just like it is in a gravitational field. Thanks again, for some very interesting new information.Best Regards,Todd D.
.....Please see the following reference (https://www.osapublishing.org/oe/fulltext.cfm?uri=oe-17-1-34&id=175583, click "Get PDF" to download the paper for free):It is shown that all modes run continuously from travelling waves through a transition to an evanescent (exponentially decaying) wave region and the value of the attenuation increases as they approach the cone vertex. A strict distinction between pure travelling waves and pure evanescent (exponentially decaying) waves cannot be achieved for conical waveguide. One mode after the other reaches cutoff in the tapered hollow metallic waveguide as they approach the cone vertex......
Getting back to the paper, based on their graphs for attenuation, it would seem a small angle is preferred. A large angle approximates a flat plate. Anything greater than pi/6 is not much better than bouncing photons off of a flat plate. However, for theta = pi/24, the attenuation is very high at much shorter wavelengths, and very high at longer wavelengths. It needs to strike a balance between energy storage and thrust at the modes available to us.
I see the attenuation factor in their plots as "similar" to that effect, acting on the microwaves in the cavity near the cut-offs. As the waves are attenuated, their momentum is absorbed as wave velocity goes to zero, just like light falling into a black hole. The result is propulsion.
Quote from: Rodal on 05/06/2015 04:11 pmQuote from: TheTraveller on 05/06/2015 04:01 pm...DO NOT reinvent the wheel.Follow Shawyer as close as you can.Plenty of clues but you need to do a lot of reading.....You are writing that in reference to Shaywer's experiments, I presume, but a number of Shawyer's prescriptions are tied to his theoretical model. I read the paper that Shawyer sent to Mulletron, to support Shawyer's theoretical model.I wrote a review of this paper here: http://forum.nasaspaceflight.com/index.php?topic=36313.msg1369861#msg1369861Showing that there is nothing in that paper (by Cullen) supporting Shawyer's theoretical model. On the contrary, it follows the same Maxwell's equations and laws followed by Greg Egan http://gregegan.customer.netspace.net.au/SCIENCE/Cavity/Cavity.html who concludes that the EM Drive should have no thrust force.The conclusions of Egan are correct when only considering radiation pressure at wavelength's that are short compared to the cut-off modes. They are incorrect because he did not take into consideration the variable speed of light inside the waveguide for wavelengths close to the cut-off modes. He used eps0 and mu0 as the permittivity and permeability of free vacuum in all his calculations of energy density and force. That is an error!The space inside the waveguide is not free vacuum, it is constrained by the waveguide. Near the cut-ff modes, his calculations are invalidated because the speed of light is not the same throughout the cavity.Best Regards,Todd D.
The sciences do not try to explain, they hardly even try to interpret, they mainly make models. By a model is meant a mathematical construct which, with the addition of certain verbal interpretations, describes observed phenomena. The justification of such a mathematical construct is solely and precisely that it is expected to work.
Quote from: Rodal on 05/06/2015 04:11 pmQuote from: TheTraveller on 05/06/2015 04:01 pm...DO NOT reinvent the wheel.Follow Shawyer as close as you can.Plenty of clues but you need to do a lot of reading.....You are writing that in reference to Shaywer's experiments, I presume, but a number of Shawyer's prescriptions are tied to his theoretical model. I read the paper that Shawyer sent to Mulletron, to support Shawyer's theoretical model.I wrote a review of this paper here: http://forum.nasaspaceflight.com/index.php?topic=36313.msg1369861#msg1369861Showing that there is nothing in that paper (by Cullen) supporting Shawyer's theoretical model. On the contrary, it follows the same Maxwell's equations and laws followed by Greg Egan http://gregegan.customer.netspace.net.au/SCIENCE/Cavity/Cavity.html who concludes that the EM Drive should have no thrust force.I did read your review that there should be no thrust. But there seems to be thrust, of a level and direction which agrees with Shawyer's theory. Which is why the Shawyer and Chinese thrust claims need to be experimentally verified or not. I believe there is enough data in the public domain to experimentally replicate their test setups, cavity designs and RF generation / feed methods, starting with the RF narrow band, spherical end plate Flight Thruster, feed via coax, which I plan to replicate in copper and if necessary in Alumininum....