Quote from: Mulletron on 05/10/2015 11:14 am....A) We should make an effort to properly characterize Finite Element solution packages like COMSOL that are able to obtain solutions to a large number of physical problems. COMSOL is not just a "wrench" but a whole tool box of solutions. Quote from: Mulletron on 05/10/2015 11:14 amthe utility of COMSOL in figuring out this problem is limited as COMSOL is considering the standing wave and isn't considering the traveling wave. It gives no consideration to what is happening over extended time (over multiple full cycles) or to what is happening to a resonant cavity under dynamic operation, for example while under acceleration. COMSOL provides no insight as to what is happening when the resonant cavity is being excited by FM or other sources of phase noise. Building off the comments about COMSOL's ability to simulate mode shapes
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the utility of COMSOL in figuring out this problem is limited as COMSOL is considering the standing wave and isn't considering the traveling wave. It gives no consideration to what is happening over extended time (over multiple full cycles) or to what is happening to a resonant cavity under dynamic operation, for example while under acceleration. COMSOL provides no insight as to what is happening when the resonant cavity is being excited by FM or other sources of phase noise. Building off the comments about COMSOL's ability to simulate mode shapes
Update on the replication attempt.I have succeeded in making a safe stable balance (finally), but I am still absolutely bombing in my attempts to get power to the balance. The slip ring approach has its faults and I'm going to have to find some sort of flexible power pickup or abandon the whole slip ring idea altogether. If I stick with this approach, I'll never get anywhere near the sensitivity of Cavendish.If I go to flying a battery and use DC-DC converters (http://www.amazon.com/dp/B00JUFJ1GA?psc=1) to power the electronics, any future of high power testing using this setup will be dashed. Not to mention I'll have to go to a much stronger torsion wire or a Dyneema braid (as opposed to the solid Dyneema line I'm using now) to hold everything up. As I know, engineering is a bunch of tradeoffs. https://goo.gl/Q3jGN1Useful references I found:http://www.alta-space.com/uploads/file/publications/feep/049-dAgostino.pdfhttp://photonicassociates.com/ISBEP4-2.pdf
Quote from: SeeShells on 05/10/2015 02:03 pmNot a single thing I built defied the laws of physics or the formulas of the trade. . . Maxwell, Ohms law, etc. If something didn't work for some weird reason, it still followed the basic laws and formulas when it ended up.It doesn't really matter to me what is happening inside of the EM Chamber it must follow the principals of physics and conservation of energy and momentum is one of them. If I have a Air Tank pressurized with 200psi of air and a audio speaker inside that can blast at 100 watts any frequency range no matter what mixture of sound or what mixture of harmonics I crank, the tank will not move, but put a hole in one end and stand back. The second law of thermodynamics states that the entropy of an isolated system never decreases and the EM Chamber is an isolated enclosed system, we think. If we are getting thrust that, thrust must be acting outside the chamber in some form. This is why I asked the simple question if smoke was used in the tests, it wasn't to detect thermal air currents but to see if it was moving away from any thrust from the EM Chamber. Smoke is small .5 to 2 um and might be be directly effected. If not then look for other forms of accelerated energy, providing thrust emanating out of the EM Chamber. I too would like to see a smoke test. I can't see conservation of momentum being violated. It just goes against everything we know both empirically and theoretically. I think that even in the off chance that the EmDrive is not experimental error, conservation of momentum will still hold albeit in a more subtle manner than the classical analysis would expect.You gave the illustrative example of a closed container with different traveling and standing waves of different frequencies and amplitudes bouncing around inside. There is a very neat quantum mechanical reason that such a container is not truly closed. Even in an infinite potential well, the wave function can extend outside the walls of the well, leading to effects such as tunneling. Another great example of the wavefunction extending beyond barriers that appears to be somewhat related to the possible effect seen here is the Aharanov Bohm effect: http://en.wikipedia.org/wiki/Aharonov%E2%80%93Bohm_effect. This is due to the wavefunction of a particle outside of a container extending past the barrier of the container and interacting with the EM field on the inside of the container.Now I leave this paper to ruminate upon:http://arxiv.org/abs/0708.0681Perhaps the EmDrive is acting as an evanescent mode photon rocket where momentum is carried away outside the cavity via this mechanism.
Not a single thing I built defied the laws of physics or the formulas of the trade. . . Maxwell, Ohms law, etc. If something didn't work for some weird reason, it still followed the basic laws and formulas when it ended up.It doesn't really matter to me what is happening inside of the EM Chamber it must follow the principals of physics and conservation of energy and momentum is one of them. If I have a Air Tank pressurized with 200psi of air and a audio speaker inside that can blast at 100 watts any frequency range no matter what mixture of sound or what mixture of harmonics I crank, the tank will not move, but put a hole in one end and stand back. The second law of thermodynamics states that the entropy of an isolated system never decreases and the EM Chamber is an isolated enclosed system, we think. If we are getting thrust that, thrust must be acting outside the chamber in some form. This is why I asked the simple question if smoke was used in the tests, it wasn't to detect thermal air currents but to see if it was moving away from any thrust from the EM Chamber. Smoke is small .5 to 2 um and might be be directly effected. If not then look for other forms of accelerated energy, providing thrust emanating out of the EM Chamber.
http://forum.nasaspaceflight.com/index.php?topic=36313.msg1326608#msg1326608I believe the series of successful vacuum tests negates the need for a smoke stick test. Comments?
Quote from: Mulletron on 05/10/2015 11:57 amUpdate on the replication attempt.I have succeeded in making a safe stable balance (finally), but I am still absolutely bombing in my attempts to get power to the balance. The slip ring approach has its faults and I'm going to have to find some sort of flexible power pickup or abandon the whole slip ring idea altogether. If I stick with this approach, I'll never get anywhere near the sensitivity of Cavendish.If I go to flying a battery and use DC-DC converters (http://www.amazon.com/dp/B00JUFJ1GA?psc=1) to power the electronics, any future of high power testing using this setup will be dashed. Not to mention I'll have to go to a much stronger torsion wire or a Dyneema braid (as opposed to the solid Dyneema line I'm using now) to hold everything up. As I know, engineering is a bunch of tradeoffs. https://goo.gl/Q3jGN1Useful references I found:http://www.alta-space.com/uploads/file/publications/feep/049-dAgostino.pdfhttp://photonicassociates.com/ISBEP4-2.pdfGreat news, hopefully all those replication attempts by individuals or small teams will shed light on relevant parameters, and you are on the forefront. Can't you you go battery without DC/DC, what are the DC requirement of your RF amplifier ?
Quote from: Mulletron on 05/10/2015 11:57 amUpdate on the replication attempt.I have succeeded in making a safe stable balance (finally), but I am still absolutely bombing in my attempts to get power to the balance. The slip ring approach has its faults and I'm going to have to find some sort of flexible power pickup or abandon the whole slip ring idea altogether. If I stick with this approach, I'll never get anywhere near the sensitivity of Cavendish.If I go to flying a battery and use DC-DC converters (http://www.amazon.com/dp/B00JUFJ1GA?psc=1) to power the electronics, any future of high power testing using this setup will be dashed. Not to mention I'll have to go to a much stronger torsion wire or a Dyneema braid (as opposed to the solid Dyneema line I'm using now) to hold everything up. As I know, engineering is a bunch of tradeoffs. https://goo.gl/Q3jGN1Useful references I found:http://www.alta-space.com/uploads/file/publications/feep/049-dAgostino.pdfhttp://photonicassociates.com/ISBEP4-2.pdfJust a wild idea, but have you considered this form of powering :http://en.wikipedia.org/wiki/Wireless_powerbasically, contact-less induction would give you frictionless movement (except for the bearing friction and air resistance) and provide power. I'm however not sure what the electromagnetic implications would be on any surrounding devices...(fe, does it act as a magnetic brake?)Secondly, not sure what would be needed to feed 1Kw of power. It might be not so practical all together...Although.... I've seen street based induction plates for loading batteries of electric cars.well.. it's just a wild idea flare...
I can remember experiments (if not the references) of time delay measurements of sub-cutoff frequency waveguide transmission. They were loudly poo-pooed at the time as claiming FTL information.
Quote from: Mulletron on 05/10/2015 11:57 amUpdate on the replication attempt.I have succeeded in making a safe stable balance (finally), but I am still absolutely bombing in my attempts to get power to the balance. The slip ring approach has its faults and I'm going to have to find some sort of flexible power pickup or abandon the whole slip ring idea altogether. If I stick with this approach, I'll never get anywhere near the sensitivity of Cavendish.If I go to flying a battery and use DC-DC converters (http://www.amazon.com/dp/B00JUFJ1GA?psc=1) to power the electronics, any future of high power testing using this setup will be dashed. Not to mention I'll have to go to a much stronger torsion wire or a Dyneema braid (as opposed to the solid Dyneema line I'm using now) to hold everything up. As I know, engineering is a bunch of tradeoffs. https://goo.gl/Q3jGN1Useful references I found:http://www.alta-space.com/uploads/file/publications/feep/049-dAgostino.pdfhttp://photonicassociates.com/ISBEP4-2.pdfThere must be some way of coupling the RF power to the cavity using feed horns or near-field antennas. That would eliminate the need to weigh down the balance with a PA, batteries or achive a workable cummutator. There may not be much gain at the frequency of interest but all you want to do is to transmit a fraction of the power. Maybe 2 identical collinear dipoles would work. The recieve dipole, mounted on the outside of the cavity, would connect to the internal loop used to drive the cavity. If you have access to a network analyzer you could optimize the match and maximize the return loss.
I need 6VDC 2A and 5VDC 2A. I guess this is a good time to explain my reasoning here. I am a firm believer that this EMdrive technology (if it is even viable) will never get off the ground if it isn't introduced and validated in a very public way. One of my original goals was to encourage replication attempts by not only academia (which has resources) but also to make it accessible to your average Joe. In keeping with the second goal, I have decided to go with Plain Jane COTS wifi gear and see if I can make something work with that. I'm well aware of how stupid that sounds.I know that the frustum design that I currently have was originally driven by a high power (and dangerous to most people) magnetron. The frequency range of your average microwave oven magnetron and wifi are the same. I verified the frustum will resonate within this frequency range using a spectrum analyzer and a SNA. Mine works on wifi channel 1 and 10. Given that Eagleworks was able to observe thrust with only 2.6 watts for one of their tests*, I think this is an acceptable risk to take. Besides, it is just money right? So I am literally driving the frustum with the RF from the wifi camera (used to observe and is riding on the experiment) and a 2watt amp. I can scale this up to 20 watts using other amps if needed. Amps are cheap and plug and play.* http://www.libertariannews.org/wp-content/uploads/2014/07/AnomalousThrustProductionFromanRFTestDevice-BradyEtAl.pdfI think the frequency hopping aspect of the waveform might end up doing me in though.So this is a gamble. I'm accepting the risk of not getting a successful replication attempt in hopes that if I do, I will have built a ready-made solution for mister tinkerer to easily observe anomalous thrust at home.If all that fails, I'll just shove in a magnetron. I deal with voltages at work (big fry your eyeballs out radars) that literally will and do make your hair stand up on end as soon as you open the cabinet, so I'm comfortable with them too.
Quote from: Notsosureofit on 05/10/2015 04:50 pmI can remember experiments (if not the references) of time delay measurements of sub-cutoff frequency waveguide transmission. They were loudly poo-pooed at the time as claiming FTL information. In the 80s I remember being poo-pooed by a physics professor when I told him the the junction speeds in an IC or even transistor was the same as sound. Acoustic speed in the IC substrate. It's true, do the numbers for amorphous silicon or GAS. I like to keep an open mind and if something new presents itself in the violation of some of our ideas of how things work, I will jump on the bandwagon.
As I've mentioned, I am a strong proponent of a completely stand-alone system when it comes to measuring purported thrust from exotic devices (propellantless thrusters). The simple act of coupling to the stationary lab frame be it via coax, RF, Galinstan contacts or whichever, brings with it the possibility of artifacts masquerading as measured thrust. The whole thing has to be in a sealed box. And even then we are not out of the woods. Thermal power will tend to "balloon" the box volume and generate a buoyancy signal if the box is in air, aligned with local gravity's direction. Charges may accumulate on the box and generate phantom forces. Magnetic fields from outside, and/or from inside, may penetrate the box and also generate phantom forces. Only in space can all these phantoms be banished.In space we need no balance; nor do we need any kind of force sensor. All we need is a measurement system to log the position of the DUT relative to its original null geodesic. This immediately kills two birds with one stone. We get a readout of initial "static" thrust from computing the initial acceleration, and, assuming actual off-geodesic motion subsequently ensues, we get the much sought-after free space dynamics.Position measurement implies an interaction. Were LIDAR to be used, we have to correct our measured positions by taking into account the "photon sail" effect. It will be small, but it may yet be of a comparable magnitude to the actual thrust we detect. Then there's solar wind because we're not going outside the heliosphere (yet). And there is a direct photon flux from the sun. All these need to be addressed as sources of error.
The smoke test is still a good idea. If the thrust proved to be due to experimental artifact, it could be due to multiple artifacts working in conjunction. Wasn't the thrust quite a bit smaller in the vacuum tests?
Wasn't the thrust quite a bit smaller in the vacuum tests?