I'm not an expert on this subject. However, since I have worked with high vacuum systems, I do know that there are still many avenues for tests (even in vacuum) to fail. High heat flux on surfaces (such as dielectrics) will inevitably liberate gases in a very high vacuum, which should be considered as ballistic mass emissions. Besides this in the image you link I don't see an error analysis. I think that the consensus in your thread is that the eagleworks data is exciting but insufficient for publication or recognition by the scientific community, and I would agree. That's why you haven't seen a Nature or Science paper yet, which you surely would have by now if these results were ironclad. The response seems to have been that tests should be run by enthusiasts in less well-controlled conditions, which will do nothing to help determine whether or not an EMdrive effect exists at all. My point is that if you want to really know the answer to that question, you should at the very least perform your experiments to the same level as Eagleworks or better. How is that considered controversial?I'll also point out that I'm quite a patient person. As an example I worked for three years on a chemical problem before obtaining publishable results. Science should be done right, rather than be done now, if you hope to get anything tractable or credible out of your experiments.
After five threads there is no statistically significant data set supporting the "EMDrive" hypothesis. More than 50% of posts in this thread now come from three members, all conducting their own amateur experiments. Interest has plummeted exponentially in this thread and on Reddit. How does any of this relate to spaceflight?
Quote from: SeeShells on 10/10/2015 02:09 pmQuote from: aero on 10/10/2015 03:44 amA question - I'm sure that it has been answered here somewhere but I don't remember the details.In which direction does the speed of light accelerate in the EM drive cavity? That is, are the EM waves moving faster as they approach the large end, or the small end of the frustum? I think it must be the large end because that fits with the idea that the waves interact with the QV and drag the virtual particles (EM disturbances in the vacuum) along with them, accelerating them toward the large end. And of course, just as in Paul March's square dance analogy, the virtual particles disappear into the QV before they do anything more than suck momentum from the EM waves of the frustum. On the other hand, I could be confused about the reaction-action-reaction phenomenon. Maybe its a triple dance step.This is really a pretty simple answer to the question of "What is the cause of the thrust?"Which Simulation would you think is causing thrust?Added: It's not that simple because both actions of this simulation can seemingly lead to thrust, it depends what theory you adhere to as to what causes thrust. This is the same simulation run, but reversed. You can see why I decided to do two different frustum excitements in my experiment.Busy day today.ShellAdded. I believe this last is EW's design but with the antennas in the small end. I don't have the loop in the big end simulation.Shell - We have ran enough simulations and members of this forum have evaluated enough EM wave propagation theory to understand that a very tiny antenna source down in the corner of the big end can not cause a symmetrically propagating resonant wave to appear within the limited start-up time available for meep computation/simulation. I haven't made that run but I will do so now that you bring it up. I expect to see a very skewed wave pattern, what do you expect? Oh, and a simulation problem. Paul reported that he rotated the loop antenna to maximize the S11 return loss. Is that to be simulated by rotating the antenna to maximize Q?
Quote from: aero on 10/10/2015 03:44 amA question - I'm sure that it has been answered here somewhere but I don't remember the details.In which direction does the speed of light accelerate in the EM drive cavity? That is, are the EM waves moving faster as they approach the large end, or the small end of the frustum? I think it must be the large end because that fits with the idea that the waves interact with the QV and drag the virtual particles (EM disturbances in the vacuum) along with them, accelerating them toward the large end. And of course, just as in Paul March's square dance analogy, the virtual particles disappear into the QV before they do anything more than suck momentum from the EM waves of the frustum. On the other hand, I could be confused about the reaction-action-reaction phenomenon. Maybe its a triple dance step.This is really a pretty simple answer to the question of "What is the cause of the thrust?"Which Simulation would you think is causing thrust?Added: It's not that simple because both actions of this simulation can seemingly lead to thrust, it depends what theory you adhere to as to what causes thrust. This is the same simulation run, but reversed. You can see why I decided to do two different frustum excitements in my experiment.Busy day today.ShellAdded. I believe this last is EW's design but with the antennas in the small end. I don't have the loop in the big end simulation.
A question - I'm sure that it has been answered here somewhere but I don't remember the details.In which direction does the speed of light accelerate in the EM drive cavity? That is, are the EM waves moving faster as they approach the large end, or the small end of the frustum? I think it must be the large end because that fits with the idea that the waves interact with the QV and drag the virtual particles (EM disturbances in the vacuum) along with them, accelerating them toward the large end. And of course, just as in Paul March's square dance analogy, the virtual particles disappear into the QV before they do anything more than suck momentum from the EM waves of the frustum. On the other hand, I could be confused about the reaction-action-reaction phenomenon. Maybe its a triple dance step.This is really a pretty simple answer to the question of "What is the cause of the thrust?"
...Just like the tests NASA EagleWorks did last year and they did test in vacuum under very controlled conditions. It's a very controversial effect that seems to defy laws of physics as we know them and if it didn't come under fire I'd be very surprised....Shell
I need to point out the testing you are suggesting in high vacuum will bring its own set of issues, amplifying some thermal effects 3-4 times versus testing in ambient air conditions. It's not a slam dunk solution. It is a wiser route for DYIers to go by testing in ambient air and account for the thermal issues as best we can and hopefully when data sets come from EagleWorks or another lab or university be dovetailed together to produce a clearer picture of what is happening.
Quote from: Tetrakis on 10/10/2015 06:40 pmAfter five threads there is no statistically significant data set supporting the "EMDrive" hypothesis. More than 50% of posts in this thread now come from three members, all conducting their own amateur experiments. Interest has plummeted exponentially in this thread and on Reddit. How does any of this relate to spaceflight?Hopefully you did not live at the time of Newton ! He would never have been allowed to share the conclusions of his experiments. You imagine : a totally uncontrolled apple falling from a tree, without any knowledge from the weather conditions, with the speed and direction of the wind totally unknown, and with a total ignorance of the possible actions of flying insects or birds ... You are certainly more a quality control integrist than somebody animated by a true scientific spirit.
Quote from: SeeShells on 10/11/2015 11:30 am...Just like the tests NASA EagleWorks did last year and they did test in vacuum under very controlled conditions. It's a very controversial effect that seems to defy laws of physics as we know them and if it didn't come under fire I'd be very surprised....ShellNo, in their published paper (July 2014) the experiment was not in vacuum. They probably did the vacuum experiment in April 2015, but we have never seen publications about it.
There appears to be a clear dependency between thrust magnitude and the presence of some sort of dielectric RF resonator in the thrust chamber. The geometry, location, and material properties of this resonator must be valuated using numerous COMSOLŪ iterations to arrive at a viable thruster solution. We performed some very early evaluations without the dielectric resonator (TE012 mode at 2168 MHz, with power levels up to ~30 watts) and measured no significant net thrust.
Quote from: Tellmeagain on 10/11/2015 04:04 pmQuote from: SeeShells on 10/11/2015 11:30 am...Just like the tests NASA EagleWorks did last year and they did test in vacuum under very controlled conditions. It's a very controversial effect that seems to defy laws of physics as we know them and if it didn't come under fire I'd be very surprised....ShellNo, in their published paper (July 2014) the experiment was not in vacuum. They probably did the vacuum experiment in April 2015, but we have never seen publications about it.In this report they talk about a vacuum chamber.
Tetrakis does raise an interesting question about vacuum systems albeit his "cheap" solution is about $7k.SeaShells notes the high cost of running in a vacuum. In a previous life I was a member of AVS and also lived the life of making vacuum systems. In fact, my first college part time job was in the chemistry department repairing mechanical pumps. Quite oily as I recall.To the Point:This community shares a lot of technical and engineering ideas. Perhaps a subtopic could be how to create an appropriate sized vacuum chamber very inexpensively.For example, jb industries makes a nice line of inexpensive pumps starting in the $250 range. The one I have, bottom of the line, easily pulls a .1 torr vacuum. A 3 gal degassing chamber on ebay starts around $100. What issues would we have to resolve to provide VAS (Vacuum As a Service) to this community? possible issues to resolve:How big a chamber is required for the DIY community? How many and what type of electrical feeds are required into the chamber? The costs in my mind's eye are in the chamber requirements.Even if the costs were too high for a single DIY project, could this community build a chamber that would support multiple projects that could be shipped as needed to support testing?Would having a VAS available change DIY project designs?
In that document, the following statement is made: QuoteThere appears to be a clear dependency between thrust magnitude and the presence of some sort of dielectric RF resonator in the thrust chamber. The geometry, location, and material properties of this resonator must be valuated using numerous COMSOLŪ iterations to arrive at a viable thruster solution. We performed some very early evaluations without the dielectric resonator (TE012 mode at 2168 MHz, with power levels up to ~30 watts) and measured no significant net thrust. Where do they account for outgassing from a big block of plastic under high thermal load?
Quote from: Tetrakis on 10/11/2015 04:33 pmIn that document, the following statement is made: QuoteThere appears to be a clear dependency between thrust magnitude and the presence of some sort of dielectric RF resonator in the thrust chamber. The geometry, location, and material properties of this resonator must be valuated using numerous COMSOLŪ iterations to arrive at a viable thruster solution. We performed some very early evaluations without the dielectric resonator (TE012 mode at 2168 MHz, with power levels up to ~30 watts) and measured no significant net thrust. Where do they account for outgassing from a big block of plastic under high thermal load?I asked the same question early on. If you do your homework, you'll find outgassing to be relatively uniform around a material, thus not contributing to any vector significantly.The perfect experiment does not exist. It is folly to assume you or anyone else can design one. The ultimate proof will not be ground-based, but space based. While your patience is lacking, many of us realize this is the very early stages of development, so none of us are expecting perfect results with our modest resources.I am surprised you do not understand development timelines and appear to be willing to discount results without further research or effort. No matter, research will go on without you and our hope is we can clear the rocket engine brick wall. If we cannot, mankind is destined to live and die on this planet when an entire universe awaits. What a sad resignation that would be.
The perfect experiment does not exist. It is folly to assume you or anyone else can design one.
No matter, research will go on without you and our hope is we can clear the rocket engine brick wall.If we cannot, mankind is destined to live and die on this planet when an entire universe awaits. What a sad resignation that would be.
Quote from: rfmwguy on 10/11/2015 05:47 pmQuote from: Tetrakis on 10/11/2015 04:33 pmIn that document, the following statement is made: QuoteThere appears to be a clear dependency between thrust magnitude and the presence of some sort of dielectric RF resonator in the thrust chamber. The geometry, location, and material properties of this resonator must be valuated using numerous COMSOLŪ iterations to arrive at a viable thruster solution. We performed some very early evaluations without the dielectric resonator (TE012 mode at 2168 MHz, with power levels up to ~30 watts) and measured no significant net thrust. Where do they account for outgassing from a big block of plastic under high thermal load?I asked the same question early on. If you do your homework, you'll find outgassing to be relatively uniform around a material, thus not contributing to any vector significantly.The perfect experiment does not exist. It is folly to assume you or anyone else can design one. The ultimate proof will not be ground-based, but space based. While your patience is lacking, many of us realize this is the very early stages of development, so none of us are expecting perfect results with our modest resources.I am surprised you do not understand development timelines and appear to be willing to discount results without further research or effort. No matter, research will go on without you and our hope is we can clear the rocket engine brick wall. If we cannot, mankind is destined to live and die on this planet when an entire universe awaits. What a sad resignation that would be.I'm not trying to advocate for the perfect at the expense of the good. Tests in the air are pointless and serve only to perpetuate hope in experimental artifacts. And as I keep saying, I'm not impatient, I just have high standards.I also did a BOTE calculation and the measured force is equivalent to about 0.7 microtorr of surface pressure in the NASA tests, which is lower than the 1 microtorr they say they achieve in their vacuum chamber. They gently warm their entire vacuum chamber from the outside, which provides no guarantee that a big piece of plastic in their UHV chamber even approaches its operating temperature during tests. Furthermore the dielectric heating will not be perfectly even but will be asymmetrically localized on the surface. My point is that only a truly tiny amount of outgassing is needed for the very best NASA data to be worthless. That the presence of a gas-sponge in the middle of the device is required for any measured force is very suspicious. I'm describing, of course, the gold standard of EMDrive data.For what its worth, I don't think anyone should build their own high vacuum chamber/setup. These things are expensive when done properly and would likely not be used enough to justify the cost. Look into renting time on an institutional chamber.
And this attitude is concerning too. You are significantly committed to finding the effect. Not just through your time and financial commitment to building a rig, but because you need it to be real.