Concerning obtaining the frequency and mode shape, does your University give you access to a Finite Element analysis package like COMSOL, or ANSYS Multiphysics, etc. so that you could then obtain a numerical solution for any arbitrary geometry and inserted dielectric ?
Quote from: dustinthewind on 05/04/2015 11:27 pmI thought this might be an alternative way of measuring small forces. Maybe it could be exploited to make a working model if some one thought it was easier to make. what is the advantage of this method over a hanging torsional pendulum or over a horizontal torsional balance ?Thanks
I thought this might be an alternative way of measuring small forces. Maybe it could be exploited to make a working model if some one thought it was easier to make.
We used to use a differential ac capacitor to measure displacement.
Quote from: WarpTech on 05/05/2015 03:40 am...I do not think it will have constant acceleration for constant power input over time, because the matter of the frustum and it's source will experience relativistic effects, on mass, time and length. It takes more than a frustum to make an actual warp drive....Question: under your interpretation, the Emdrive would have a maximum speed always less than c, because acceleration would eventually decrease until maybe becoming zero due to relativistic effects on the frustum at some speed. Is that correct?If so, what speed are we talking about? something close to c or much lower?This topic of the Emdrive's maximum speed and the potentially diminishing acceleration is something that has appeared repeatedly in the discussions, without a clear answer yet because there is no experimental data backing it or disproving it yet.This notion has also been rebuffed by some people, because assuming a "maximum speed" also assumes a privileged reference frame, which is a big no no in current theories.I feel there could be a GR explanation, related to the fact that we do have an absolute speed limit: the speed of light, which is the same on all reference frames, including that of the microwaves inside the frustum.
...I do not think it will have constant acceleration for constant power input over time, because the matter of the frustum and it's source will experience relativistic effects, on mass, time and length. It takes more than a frustum to make an actual warp drive....
Quote from: Rodal on 05/05/2015 12:28 amQuote from: dustinthewind on 05/04/2015 11:27 pmI thought this might be an alternative way of measuring small forces. Maybe it could be exploited to make a working model if some one thought it was easier to make. what is the advantage of this method over a hanging torsional pendulum or over a horizontal torsional balance ?ThanksNotsureofit seems to know from the quote. Quote from: Notsosureofit on 05/04/2015 11:44 pmWe used to use a differential ac capacitor to measure displacement.He might have more experience with it than I. I would guess you can increase the surface of the capacitor to increase your sensitivity. A lock-in amplifier can eliminate noise and amplifiers can further amplify the signal from the capacitor. It is an alternative to other ways of measuring. I'm wondering if there might be a way to tune the rate of natural osculation of the system by applying a small offset DC voltage (of the AC wave to used to measure capacitance) as a way of tuning. There might be some give and take compared to other methods. I haven't ever personally used one.
About the possible interpretation of this effect, if confirmed, I would like to point out that a plane wave implies a modified metric in general relativity. This has been presented in Misner, Thorne, Wheeler, Gravitation at section 35.11 page 961. You can also find a Wikipedia entry describing it. For the article used in the measurements the situation is more involved as the frustum has not just a single mode but, in principle, each one of these can be seen as propagating in a modified metric. The smaller the input power the smaller the effect. It is my conviction that a full understanding could be achieved with a proper treatment using general relativity. What I have found in literature is overlooking any analysis of the interaction between microwaves and space-time. The effect is miniscule in any case but the interferometer devised at Eagleworks seems well equipped to unveil it.
TheTraveler, the RF generator/amplifier/etc could be placed on the scale as part of the counter weight, no floating RF cables this way. Power supply could come up from the center.There is also need for a down pointing arm from center with a weight for stability.This setup should not be affected by buckling.
The limit is on acceleration not speed.
Quote from: Giovanni DS on 05/05/2015 01:30 pmTheTraveler, the RF generator/amplifier/etc could be placed on the scale as part of the counter weight, no floating RF cables this way. Power supply could come up from the center.There is also need for a down pointing arm from center with a weight for stability.This setup should not be affected by buckling.RF gen & wide band RF amp need pwr and USB connections. Probably better to feed a single & thin RF cable up through a hole in the teeter totter centre and then to left side EM Drive but leave the electronics on the bench.The balance beam will be at least 200mm wide (bit wider than EM Drive external support rods), with through axle & 2 side bearings, so should be no stability issues. Design like kids teeter totter. Simple. KISS.Roger no thermal buckling or CG movement issues.The 4 EM Drive external rod supports will sit on one end on the Teeter Totter. Sorry girls I need your Teeter Totter.
....Thank you for the interesting questions, Dr. Rodal.I do not think it will have constant acceleration for constant power input over time, because the matter of the frustum and it's source will experience relativistic effects, on mass, time and length. It takes more than a frustum to make an actual warp drive.For now, I'm not certain that having the resonance occur inside the frustum is necessary. Resonance could occur in an exterior chamber, like pumping a "laser", something to pump the input power. Then inject a tuned coherent pulse of limited bandwidth into the frustum near it's cut-off modes. The objective being, to use the variable refractive index to amplify the momentum toward the small end. By this I mean, the momentum transforms due to the refractive index,p => p*sqrt(c/vg)The group velocity depends on location in the frustum and is lowest at the small end. So momentum is amplified toward the small end. The energy is not lost through resistive copper losses, it is absorbed through momentum transfer of the exponentially decaying waves that have been squeezed beyond their cut-off diameter in the waveguide. For these waves, the speed of light has come to a halt and they cannot propagate, so their momentum must be absorbed by the frustum. Where else can it go? They have crossed the event horizon, where c -> 0, the momentum can't escape.The resonant modes are probably not so close to the cut-off and contribute very little, if anything. There is still a gradient in v group, but a much, much smaller one. I would consider this a different design, one that optimizes Q and very high energy storage over thrust, but the result will work for the same reason.You also asked me for some equations, graphs and such. I've just started researching here and found an enormous body of information I did not know about. So... it may be a while. Any questions you may have on the PV Model and my quantum electrodynamic interpretation of it, I'm happy to assist. Best Regards,Todd D.
Quote from: Notsosureofit on 05/05/2015 10:55 amThe limit is on acceleration not speed.Yes but only when observed from a reference frame. Traveller's accelleration (from travellers PoV) reduces as a square root and that is not asymptotically (the limit you stated). If it were, speed from the traveller's frame of reference could never grow toward infinity, which it can occording to GR.
while realizing my knowledge of electromagnetism falls short compared to level that is discussed here, i do have a question about that interesting idea on momentum transfer of the waves : -with the law on conservation of energy in the back of my head - How can the momentum transfer of a wave be bigger then the energy contained in a photon, as seen in a pure photon rocket ? I believe calculations showed the forces observed in the frustum are many times (100? 1000?) greater then what a photon rocket would be able to produce...Due to the duality of microwave being a photon particle and a wave at the same time, shouldn't the energy contained in a wave/particle be the same?Is it because for a photon rocket only a small portion of that energy is used for kinetic motion, while in the momentum transfer a greater part of the energy is transferred?
Quote from: ppnl on 05/04/2015 08:37 pmQuote from: WarpTech on 05/04/2015 07:47 pm<snip>Not yet... I'm just now coming to grips with this myself. My light-bulb went off when I realized if the frequency of the microwaves is very close to the cut-off frequencies, then the speed of light will have a very large gradient inside the Frustum. Relative to the "traveling" waves (photons) attempting to move at the speed of light from end to end. When they approach the small end, their wavelength is squeezed by the reduced group velocity. Momentum depends on wavelength;p = h/lambdawavelength depends on velocity, and v_g is a variable inside the frustum. That is where the momentum is coming from. Inside the Frustum, relative to the traveling waves you have an accelerated reference frame, into which you are injecting photons that are affected by this manufactured "gravitational" field, that must be compensated for by moving the Frustum.I'll see what I can come up with for a formal equation, but I've got a day job. As for @ppnl, you will never get a Newtonian-type COM equation out of this. The two frames are the Frustum, and the frame of the moving photons inside it. The acceleration is caused by the geometry of the waveguide or a variable refractive index, i.e. the GR or PV Interpretation lead to the same result.Todd D.Well I certainly agree that You will never get Newtonian-type COM equation out of this. That's what makes it a violation of COM. Hard and simple. You are free to develop a theory that does not conserve momentum but you should call it what it is.And I don't care what frames are inside the thing. Frames of reference are mathematical fictions. They don't exist. I should not need two frames of reference but only one and it is chosen only for convenience not truth. Any frame should do. Again you are free to develop a theory with a preferred frame that is real but you need to know that that is what you are doing and tell people that that is what you are doing.If you insist on using Newtonian mechanics, then you will never understand COM in terms of General Relativity. I have not formulated a "new" theory, I'm using GR correctly. If you learn how to do COM in GR, then you would have no trouble seeing that this does indeed conserve momentum. The fact that you "don't care what is inside" is what is preventing you from learning. The "gravitational" field effect of a variable speed of light, acting on the photons inside the Frustum is what makes it move. If you neglect that it has a gravitational field inside it, then you neglect the very essence of how it works and why momentum is conserved. If you want to neglect GR and "believe" COM is violated, then that is your prerogative. As for why it was not discovered already, I'm kicking myself in the a** for not thinking of this setup 10 years ago when I realized we can mimic gravity over a limited bandwidth with much less energy than over the full bandwidth of all light and matter waves. When my colleague and I wrote our EGM III paper, we had a resonant cavity like this in mind, but we didn't consider the taper.Best Regards,Todd D.
Quote from: WarpTech on 05/04/2015 07:47 pm<snip>Not yet... I'm just now coming to grips with this myself. My light-bulb went off when I realized if the frequency of the microwaves is very close to the cut-off frequencies, then the speed of light will have a very large gradient inside the Frustum. Relative to the "traveling" waves (photons) attempting to move at the speed of light from end to end. When they approach the small end, their wavelength is squeezed by the reduced group velocity. Momentum depends on wavelength;p = h/lambdawavelength depends on velocity, and v_g is a variable inside the frustum. That is where the momentum is coming from. Inside the Frustum, relative to the traveling waves you have an accelerated reference frame, into which you are injecting photons that are affected by this manufactured "gravitational" field, that must be compensated for by moving the Frustum.I'll see what I can come up with for a formal equation, but I've got a day job. As for @ppnl, you will never get a Newtonian-type COM equation out of this. The two frames are the Frustum, and the frame of the moving photons inside it. The acceleration is caused by the geometry of the waveguide or a variable refractive index, i.e. the GR or PV Interpretation lead to the same result.Todd D.Well I certainly agree that You will never get Newtonian-type COM equation out of this. That's what makes it a violation of COM. Hard and simple. You are free to develop a theory that does not conserve momentum but you should call it what it is.And I don't care what frames are inside the thing. Frames of reference are mathematical fictions. They don't exist. I should not need two frames of reference but only one and it is chosen only for convenience not truth. Any frame should do. Again you are free to develop a theory with a preferred frame that is real but you need to know that that is what you are doing and tell people that that is what you are doing.
<snip>Not yet... I'm just now coming to grips with this myself. My light-bulb went off when I realized if the frequency of the microwaves is very close to the cut-off frequencies, then the speed of light will have a very large gradient inside the Frustum. Relative to the "traveling" waves (photons) attempting to move at the speed of light from end to end. When they approach the small end, their wavelength is squeezed by the reduced group velocity. Momentum depends on wavelength;p = h/lambdawavelength depends on velocity, and v_g is a variable inside the frustum. That is where the momentum is coming from. Inside the Frustum, relative to the traveling waves you have an accelerated reference frame, into which you are injecting photons that are affected by this manufactured "gravitational" field, that must be compensated for by moving the Frustum.I'll see what I can come up with for a formal equation, but I've got a day job. As for @ppnl, you will never get a Newtonian-type COM equation out of this. The two frames are the Frustum, and the frame of the moving photons inside it. The acceleration is caused by the geometry of the waveguide or a variable refractive index, i.e. the GR or PV Interpretation lead to the same result.Todd D.
Here is my KISS EMDrive test system rough draught.The EM Drive will sit on top of but not connected to one end of a balance beam. On the other will be an adjustable counter balance mass. Very low stiction bearings will be used.The EM Drive end of the balance beam will sit on top of but not connected to a digital load cell with a 0.01g resolution / 0.5kg max and be connected via USB to a laptop running data logger software. Would like more resolution, will see how the budget goes.The counter balance will be adjusted to produce a down force on the load cell of 0.25kg when the EM Drive is unpowered so to bias the load cell into the middle of it's range.The frequency and power adjustable RF source will be connected to the EM Drive by a free floating length of coax with SWR matching capability and to the laptop via USB connector. Control of frequency and power will be via software on the laptop.Fairly long power pulses of of upto 2 minutes will be applied to the EM Drive as per Shawyer's 1st test protocol. http://emdrive.com/feasibilitystudy.htmlThe idea is to keep this KISS and stay as close to the 1st Shawyer test setup that also used vertical orientation of the EM Drive.Based on achieving 10mN/kW (~1gf/kW) performance, the desired 0.1gf (10x load cell resolution) will need the application of 100W of RF power.Desire is to use common 2.4GHz narrow band WiFi based signal generators which can be smoothly varied in frequency and power output to find optimal cavity frequency and energy loading.As this is a narrow band RF signal, ideally the end caps should be spherical to eliminate end plate variable phase change and to get a much better cavity Q. But being a realist and KISS engineer, who hates to reinvent the wheel, will start with simpler flat plates and will follow the excellent work of Mullerton.Comments most welcome