If space time is being bent, and the bend is symmetrical, the non-thrusting (smaller) end plate should have an opposite attracting (pulling) force rather than a repulsive (pushing) force.Could these forces be detected by Iulian in his test setup. So, rather than hang the drive on the scales, place the drive on the floor, then hang a weight on the scale that lies as close to the end plate as possible. Then repeat for the other plate.
Quote from: TheTraveller on 05/25/2015 02:40 pm...As mentioned I have silver epoxy and will be using it as the 1st 2 layers, then using the Copper/Metal epoxy for an overcoat. My experience with silver epoxy is that it doesn't have a lot of strength and can't be replied on to generate a physically strong joint...The silver epoxy has a film thickness dependent conduction behavior (due to the percolation behavior of the conductive particles and the viscosity of the epoxy). The resistivity levels are reduced as the adhesive film thickness increases. Conversely, when the thickness is reduced significantly, a significant increase in resistivity is observed coupled with a significant increase in the slope of the resistivity-thickness curve. On the other hand, as the thickness increases, the strength decreases. So, getting it right is an art
...As mentioned I have silver epoxy and will be using it as the 1st 2 layers, then using the Copper/Metal epoxy for an overcoat. My experience with silver epoxy is that it doesn't have a lot of strength and can't be replied on to generate a physically strong joint...
I do believe what we see in the 2nd image to the left of the Red RF feed may not be an impedance matching system but instead an arm that extends inside the Flight Thruster such that Shawyer can fine tune the antenna position. It appears to have a small arm / crank on the left end and the ability to slide in and out.
Quote from: TheTraveller on 05/25/2015 01:59 pmI do believe what we see in the 2nd image to the left of the Red RF feed may not be an impedance matching system but instead an arm that extends inside the Flight Thruster such that Shawyer can fine tune the antenna position. It appears to have a small arm / crank on the left end and the ability to slide in and out.Eagle Eyes!Yes, I agree, that's exactly what it appears to be. Would the crank move the launcher/antenna up and down - or side to side?
Quote from: zaphod_vi on 05/25/2015 02:56 pmIf space time is being bent, and the bend is symmetrical, the non-thrusting (smaller) end plate should have an opposite attracting (pulling) force rather than a repulsive (pushing) force.Could these forces be detected by Iulian in his test setup. So, rather than hang the drive on the scales, place the drive on the floor, then hang a weight on the scale that lies as close to the end plate as possible. Then repeat for the other plate.That's an interesting experiment in that it is independent of the cavity errors. If we look at something like Eq. 14 in Marco's paper, we might expect to see nothing for a perfectly conducting cavity. Copper isn't perfect, so there may be an effect due to dielectric (or magnetic) leakage. In any event, an independent weight measurement would be much less noisy, I would think. (so more sensitive, as required)
Regarding antenna placement. In Meep, exciting the electric modes, I have good success achieving resonance when I place the antenna one-half wavelength from the end of the cavity (cylindrical cavity). What does the theory say about antenna placement to achieve resonance?Note that this works well even when I change the drive frequency as long as the frequency is near the resonant frequency of a mode of the cavity. Meep excites with a noisy (Gaussian) source and zeros in on the resonance frequency without to much fiddling this way.
Has anyone ever tried to detect radiation at any frequency outside of the cavity? Theoretically I think there should be none but has that been verified?
The field strengths within the thruster equate to a power level of 17MW. Signal leakage causes EMC effects within the fixed video camera. This leads to the apparent vertical movements.
Quote from: Notsosureofit on 05/25/2015 03:32 pmQuote from: zaphod_vi on 05/25/2015 02:56 pmIf space time is being bent, and the bend is symmetrical, the non-thrusting (smaller) end plate should have an opposite attracting (pulling) force rather than a repulsive (pushing) force.Could these forces be detected by Iulian in his test setup. So, rather than hang the drive on the scales, place the drive on the floor, then hang a weight on the scale that lies as close to the end plate as possible. Then repeat for the other plate.That's an interesting experiment in that it is independent of the cavity errors. If we look at something like Eq. 14 in Marco's paper, we might expect to see nothing for a perfectly conducting cavity. Copper isn't perfect, so there may be an effect due to dielectric (or magnetic) leakage. In any event, an independent weight measurement would be much less noisy, I would think. (so more sensitive, as required)How could you visualize the Em waveforms of a thrust mode outside the cavity if somehow and still keeping the cavity shape and TM or TE resonate mode? (yes I know the copper is reflecting or absorbing the EM waves) Does this make sense in how I said it? Like a virtual wave? I'd try it without asking, but just don't have the software.
...All good points. I believe she is trying to facilitate using Maxwell's equations by imagining there are particles inside the volume. Maxwell's equations are difficult, this is a crutch. Where she is making her mistake is that there actually are charged particles inside the volume, (besides air) they are not imaginary, they are confined to within the skin effect depth of the metal. The skin effect is inside the volume of integration for the Divergences, and it contains both positive and negative charges. Typically, we ignore the force acting on the lattice ions, since their mass is so much greater than the electrons, but they are there and they do scatter, vibrate and transfer momentum from the field to the frustum.Unfortunately, she does not elaborate on the actual expressions of E and H, that would depend on the geometry, attenuation, phase, etc... she leaves that to the results table of her FEA. But the force equation she ends up with is still the correct equation. Its correctness, as always, depends on the accuracy of what you plug-in for E and H at the boundary, and the duty cycle of the power consumption. Therefore, if you know what to plug in, it's only a "minor" issue in her example and explanation, not in the actual FEA which is supposedly a realistic simulation of a brass cavity.
with air as filling medium and electric wall boundary condition,
With four parameters I can fit an elephant, and with five I can make him wiggle his trunk.
Quote from: Paul Novy on 05/25/2015 11:52 amQuote from: TheTraveller on 05/25/2015 11:37 amPlan is to laser cut all the pieces from 0.5mm thick copper sheet. Have found a company that can do a proper roll of the frustum so the side joint is a butt joint. Same company can form the spherical end plates.1) UL certified Copper epoxy will be used to join the 2 end flanges to the frustum and then cover the butt joint.http://www.supergluecorp.com/super-glue/epoxies/copper-bond Does anyone have an opinion on this joining method?I would go for an old fashioned soldering. Why introduce another unknown variables caused by the glue?BTW. I wanted to say Hi to the whole community. I've been around for a while reading, now I'll try to throw my 5 cents from the point of view of a mechatronic engineer... well if I have something useful to say.Thanks for the comment.I have concerns about the frustum warping when using soldering. Have built stuff before using thin copper plate, know it moves and the final soldered positions may not be the unsoldered position.As I see it, making sure the 2 end plates are highly parallel and joined to the frustum at the same angle ensures the highest Q I can get. Using a cold assembly method should ensure the money I'm paying for laser cutting, to ensure everything is at the right angles to each other, will pay dividends.
Quote from: TheTraveller on 05/25/2015 11:37 amPlan is to laser cut all the pieces from 0.5mm thick copper sheet. Have found a company that can do a proper roll of the frustum so the side joint is a butt joint. Same company can form the spherical end plates.1) UL certified Copper epoxy will be used to join the 2 end flanges to the frustum and then cover the butt joint.http://www.supergluecorp.com/super-glue/epoxies/copper-bond Does anyone have an opinion on this joining method?I would go for an old fashioned soldering. Why introduce another unknown variables caused by the glue?BTW. I wanted to say Hi to the whole community. I've been around for a while reading, now I'll try to throw my 5 cents from the point of view of a mechatronic engineer... well if I have something useful to say.
Plan is to laser cut all the pieces from 0.5mm thick copper sheet. Have found a company that can do a proper roll of the frustum so the side joint is a butt joint. Same company can form the spherical end plates.1) UL certified Copper epoxy will be used to join the 2 end flanges to the frustum and then cover the butt joint.http://www.supergluecorp.com/super-glue/epoxies/copper-bond Does anyone have an opinion on this joining method?
Quote from: TheTraveller on 05/25/2015 12:04 pmQuote from: Paul Novy on 05/25/2015 11:52 amQuote from: TheTraveller on 05/25/2015 11:37 amPlan is to laser cut all the pieces from 0.5mm thick copper sheet. Have found a company that can do a proper roll of the frustum so the side joint is a butt joint. Same company can form the spherical end plates.1) UL certified Copper epoxy will be used to join the 2 end flanges to the frustum and then cover the butt joint.http://www.supergluecorp.com/super-glue/epoxies/copper-bond Does anyone have an opinion on this joining method?I would go for an old fashioned soldering. Why introduce another unknown variables caused by the glue?BTW. I wanted to say Hi to the whole community. I've been around for a while reading, now I'll try to throw my 5 cents from the point of view of a mechatronic engineer... well if I have something useful to say.Thanks for the comment.I have concerns about the frustum warping when using soldering. Have built stuff before using thin copper plate, know it moves and the final soldered positions may not be the unsoldered position.As I see it, making sure the 2 end plates are highly parallel and joined to the frustum at the same angle ensures the highest Q I can get. Using a cold assembly method should ensure the money I'm paying for laser cutting, to ensure everything is at the right angles to each other, will pay dividends.It's very easy to cut thin copper with metal shears. Inside curves are a little tricky but a straight edge linoleum knife works well. Epoxy may work for joining the pieces if the joints are tab joints. Otherwise handling and heating will make it come apart. Conductive epoxy is an insulator at RF frequencies, due to the skin effect. Silver fill Copper or Brass is one option. This product has a thin layer of Sterling Silver bonded to Copper or Brass sheet. The Silver layer is thicker than plating. I don't know who makes it now and you would really want fine Silver (999) anyway because Sterling Silver has a lower conductivity than Copper. Silver plating, to achieve better RF skin layer conductivity than Copper is not easy to do. If you really wanted to optimize this em-drive cavity you could use 24 K Gold plated Fine Silver sheet. Gold is actually a better conductor at RF frequencies when skin effects, etc are considered; although Fine Silver is the best room temperature conductor at DC and low RF frequencies.
Safe and easy to use Copper-BondŽ is UL listed for joining copper tube used in fire sprinkler systems and NSF approved for hot and cold water systems.
Quote from: WarpTech on 05/25/2015 03:16 pm...All good points. I believe she is trying to facilitate using Maxwell's equations by imagining there are particles inside the volume. Maxwell's equations are difficult, this is a crutch. Where she is making her mistake is that there actually are charged particles inside the volume, (besides air) they are not imaginary, they are confined to within the skin effect depth of the metal. ...Let's agree that real charged particles (with the EM Drive in a vacuum) are confined within the skin depth of the material. (...)No, the indications are that to simultaneously model the skin effect with a Finite Element model is not practically feasible and that's why she doesn't describe it.On the contrary, she states that she effectively did not model the skin effect with a finite element discretization, see page 9, section 3.2 "Thrust calculation" where she states:Quote with air as filling medium and electric wall boundary condition,So what she did was, instead of modeling the skin effect with a finite element discretization, she simply modeled it as a boundary condition.Since we know that one cannot get a net force (averaged over an integer number of time periods) without charged particles in the cavity medium, or without a constitutive model describing absorption in the skin, either we have to take her at her word that she modeled the medium in the cavity as having charged particles, or that she used a separate equation to model the skin effect (not a finite element discretization of the skin effect).Therefore, she must have some undisclosed free parameters, either modeling virtual charged particles in the medium in the cavity (air) or in her formula for the skin effect.(...)
...All good points. I believe she is trying to facilitate using Maxwell's equations by imagining there are particles inside the volume. Maxwell's equations are difficult, this is a crutch. Where she is making her mistake is that there actually are charged particles inside the volume, (besides air) they are not imaginary, they are confined to within the skin effect depth of the metal. ...
...Correct, she has undisclosed free parameters! That is what I meant when I said she did not elaborate on her expressions for E and H. Technically, she does not need to model the skin effect in her FEA. She simply needs to express her E and H amplitudes with an exponential attenuation factor...
Quote from: WarpTech on 05/25/2015 05:16 am...I also think I found a (minor?) error in the 2013 paper. In my estimation, equations 4 and 6 are correct. Where I disagree is that her premise is that there are charged particles in the volume, and then on equations 7 and 8, she removes the particle momentum density and the energy density of the field, for no apparent reason and then IMO, she abruptly ends the section....Can you please elaborate why youthink this is, maybe, just a (minor) error by Prof. Yang and her co-authors?(And by the way, I am looking at the 2010 paper, not the 2013 paper, in my comments below)They write (2010 paper, translation page 4, original page 28)http://www.emdrive.com/NWPU2010translation.pdfQuoteIf the microwave electromagnetic field consists of charge particles, due to theelectromagnetic force, the charge particles can travel within the electromagneticfield, so the charge particles can acquire energy and momentum from theelectromagnetic field. This indicates that electromagnetic field have energy andmomentum. The microwave electromagnetic field inside the cavity is composed of photons (at microwave frequencies), which as we all know, have no charge whatsoever. So the microwave electromagnetic field does not consist of charge particles (unless one considers the virtual particles of the QV or one considers ionized air). This is the difference between Greg Egan's equations http://gregegan.customer.netspace.net.au/SCIENCE/Cavity/Cavity.html, who finds no net thrust force, since he doesn't consider this term at all.If there are any charges and currents, they are only present in the copper metal (translation says "brass"), and not inside the empty microwave cavity. This seems to me a major issue, and not a minor point.The original 2010 paper in Chinese (http://www.emdrive.com/NWPU2010paper.pdf) says (my translation)QuoteThe microwave electromagnetic field of charged particles , if present , due to the electromagnetic force The "if present" seems to have been translated to "if it consists of". Either way, "If present" or "if it consists of" is a big if. We have to understand whether this condition is met, and if so, what are these charged particles.Are the authors considering charged particles to be present in the empty cavity? In essence are the authors effectively considering virtual charged particles like the QV of Dr. White ?Or are the authors considering having ionized air inside the cavity ? (one example: http://www.jpier.org/PIERM/pierm26/20.12101201.pdf )
...I also think I found a (minor?) error in the 2013 paper. In my estimation, equations 4 and 6 are correct. Where I disagree is that her premise is that there are charged particles in the volume, and then on equations 7 and 8, she removes the particle momentum density and the energy density of the field, for no apparent reason and then IMO, she abruptly ends the section....
If the microwave electromagnetic field consists of charge particles, due to theelectromagnetic force, the charge particles can travel within the electromagneticfield, so the charge particles can acquire energy and momentum from theelectromagnetic field. This indicates that electromagnetic field have energy andmomentum.
The microwave electromagnetic field of charged particles , if present , due to the electromagnetic force
One defense for this hypotheses is the difference in measured effects between the Yang and Sawyer devices and the Eagleworks vacuum tests.