doing frustum research in frankenmuth michigan today

This short length, constant diameter, cylindrical step out ("retraction" size of the cover depth) design also seems to eliminate the need for spherical end plates, which would be a really big win.

Quote from: TheTraveller on 07/26/2015 04:09 PMThis short length, constant diameter, cylindrical step out ("retraction" size of the cover depth) design also seems to eliminate the need for spherical end plates, which would be a really big win.Yes but the Chinese used a noisy 1000W magnetron, which has AM and FM modulation over a wider bandwidth than your cleaner solid-state 100W RF amp. I remember Shawyer told you to use a magnetron with flat end plates, but a narrow-band emitter with spherical ends.

Quote from: flux_capacitor on 07/26/2015 12:40 PMQuote from: Rodal on 07/26/2015 12:33 PMQuote from: flux_capacitor on 07/26/2015 12:18 PM...EDIT: I didn't understand kr was actually k * rSo it depends on frequency besides distance from the apex.I agree, when I first saw the notation kr in Yang and Fan's paper I found that confusing too, as it could be interpreted as k sub r, a variable instead of two variables multiplied by each other. I don't like the notation kr. It would be better if the multiplication sign would be included or if big separation would be included to make it clear that it is the product of two variables, one of the variables (k) dependent on wavelength, and hence dependent on frequency.I concur. Following this idea: since k = 2 Pi/wavelengthA small k implies a longer wavelength so a lower frequency.A small k*r is dimensionless but implies both a low operating frequency and a short distance from the apexIn a closed cavity there are two ways of getting closer to the apex:1- Increase the cone angle so the apex is closer to the small end plateor2- Make the end plate as smaller as possibleSince we saw Yang's design with a low cone angle is more efficient, we should not try (1) but (2). Which is difficult since the lower the frequency, the bigger the frustum.Am I right on this?But how the group velocity can become superluminal while it decreases is still beyond me.It should be explored, but until a theory is corroborated to explain the anomalous thrust, what is optimal will not be knownEDIT: but yes, getting closer to the apex is interesting, that's why I wrote the paper about the fact that strong cut-off doesn't apply to conical cavities. Getting close to the apex brings up General Relativity and other interesting things into the picture. However, getting close to the apex may also affect the Q. It needs to be tested

Quote from: Rodal on 07/26/2015 12:33 PMQuote from: flux_capacitor on 07/26/2015 12:18 PM...EDIT: I didn't understand kr was actually k * rSo it depends on frequency besides distance from the apex.I agree, when I first saw the notation kr in Yang and Fan's paper I found that confusing too, as it could be interpreted as k sub r, a variable instead of two variables multiplied by each other. I don't like the notation kr. It would be better if the multiplication sign would be included or if big separation would be included to make it clear that it is the product of two variables, one of the variables (k) dependent on wavelength, and hence dependent on frequency.I concur. Following this idea: since k = 2 Pi/wavelengthA small k implies a longer wavelength so a lower frequency.A small k*r is dimensionless but implies both a low operating frequency and a short distance from the apexIn a closed cavity there are two ways of getting closer to the apex:1- Increase the cone angle so the apex is closer to the small end plateor2- Make the end plate as smaller as possibleSince we saw Yang's design with a low cone angle is more efficient, we should not try (1) but (2). Which is difficult since the lower the frequency, the bigger the frustum.Am I right on this?But how the group velocity can become superluminal while it decreases is still beyond me.

Quote from: flux_capacitor on 07/26/2015 12:18 PM...EDIT: I didn't understand kr was actually k * rSo it depends on frequency besides distance from the apex.I agree, when I first saw the notation kr in Yang and Fan's paper I found that confusing too, as it could be interpreted as k sub r, a variable instead of two variables multiplied by each other. I don't like the notation kr. It would be better if the multiplication sign would be included or if big separation would be included to make it clear that it is the product of two variables, one of the variables (k) dependent on wavelength, and hence dependent on frequency.

...EDIT: I didn't understand kr was actually k * rSo it depends on frequency besides distance from the apex.

@WarpTechwas confused yesterday caused by the notification "kr". Dr Rodal posted the description of what is meaning it (namely not the radii of the cone at a given point at the z-axis, but the radius based on the cone apex).@Rodal Thanks for the explanationhttp://forum.nasaspaceflight.com/index.php?topic=37642.msg1409751#msg1409751

Quote from: deltaMass on 07/26/2015 04:15 PMSome experimenters would be pretty content with about 100 uN but Tajmar gets about that in the direction at right angles to the frustum axis (labelled "Horizontal" on his graph). Having read through the foregoing posts, it seems likely that the huge waveguide orifice has something to do with this. He's basically extended the cavity geometry a little way at right angles to the frustum main axis.Excellent observation, deltaMass. In retrospect this is almost obvious, but it is not pointed out in the paper as a possible explanation for the side force.This is another possible question to discuss with Tajmar at the AIAA presentation.

Some experimenters would be pretty content with about 100 uN but Tajmar gets about that in the direction at right angles to the frustum axis (labelled "Horizontal" on his graph). Having read through the foregoing posts, it seems likely that the huge waveguide orifice has something to do with this. He's basically extended the cavity geometry a little way at right angles to the frustum main axis.

Quote from: Rodal on 07/26/2015 04:45 PMQuote from: deltaMass on 07/26/2015 04:15 PMSome experimenters would be pretty content with about 100 uN but Tajmar gets about that in the direction at right angles to the frustum axis (labelled "Horizontal" on his graph). Having read through the foregoing posts, it seems likely that the huge waveguide orifice has something to do with this. He's basically extended the cavity geometry a little way at right angles to the frustum main axis.Excellent observation, deltaMass. In retrospect this is almost obvious, but it is not pointed out in the paper as a possible explanation for the side force.Is it this one?This is another possible question to discuss with Tajmar at the AIAA presentation.Those with access to the paper can check that maybe the vertical set-up of frustum (on horizontal balance measurement) is with the waveguide axis aligned with arm : if we define a plane with both the axis of frustum and axis of waveguide, thrust would be expected only in this plane of symmetry, if this plane is parallel to vertical axis of rotation it would come as a surprise that there is some measured thrust vector orthogonal to such plane of symmetry, by symmetry argument alone, regardless of possible mechanisms unless some very strong (and strange) kind of parity breaking, i.e. naming axis of frustum is X and waveguide is (roughly orthogonal) Y it's like measuring net thrust on Z, sorry for the clumsy wording...

Quote from: deltaMass on 07/26/2015 04:15 PMSome experimenters would be pretty content with about 100 uN but Tajmar gets about that in the direction at right angles to the frustum axis (labelled "Horizontal" on his graph). Having read through the foregoing posts, it seems likely that the huge waveguide orifice has something to do with this. He's basically extended the cavity geometry a little way at right angles to the frustum main axis.Excellent observation, deltaMass. In retrospect this is almost obvious, but it is not pointed out in the paper as a possible explanation for the side force.Is it this one?This is another possible question to discuss with Tajmar at the AIAA presentation.

Quote from: X_RaY on 07/26/2015 05:56 PM@WarpTechwas confused yesterday caused by the notification "kr". Dr Rodal posted the description of what is meaning it (namely not the radii of the cone at a given point at the z-axis, but the radius based on the cone apex).@Rodal Thanks for the explanationhttp://forum.nasaspaceflight.com/index.php?topic=37642.msg1409751#msg1409751I'm not confused by this. I know that kr = k*r, is the distance from the cone apex in terms of phase. I agree the paper is confusing in the way it is written because they also use k_{r}. In my equation for the tapered cylinder using Bessel functions, I had z*w/c, which is the same thing. For a given k value based on the input frequency, k being the wavenumber of the propagating mode in the z direction, r is the distance from the apex. It is simply their way of normalizing the graph, because computing the Hankle functions is easier that way. The graphs I posted for the Reissner-Nordstrom metric are equivalent representations for k=1, where r is the radial coordinate. It is the radial solution for a charged black hole. What is wrong with that? What we are dealing with is a frequency dependent, electromagnetic metric. It does not affect matter the way normal gravity would, but it does effect the EM waves that fall in the right bandwidth in such a way as to mimic gravity. Todd

Quote from: frobnicat on 07/26/2015 06:29 PMThose with access to the paper can check that maybe the vertical set-up of frustum (on horizontal balance measurement) is with the waveguide axis aligned with arm : if we define a plane with both the axis of frustum and axis of waveguide, thrust would be expected only in this plane of symmetry, if this plane is parallel to vertical axis of rotation it would come as a surprise that there is some measured thrust vector orthogonal to such plane of symmetry, by symmetry argument alone, regardless of possible mechanisms unless some very strong (and strange) kind of parity breaking, i.e. naming axis of frustum is X and waveguide is (roughly orthogonal) Y it's like measuring net thrust on Z, sorry for the clumsy wording...Thanks, I have authorized access to the paper but I had not checked that. What figure in the paper are you referring to ? is it this one?I enclose strictly for discussion, research and illustration purposes Fig. 7 c of Tajmar et.al. about torsional pendulum...http://arc.aiaa.org/doi/pdf/10.2514/6.2015-4083

Those with access to the paper can check that maybe the vertical set-up of frustum (on horizontal balance measurement) is with the waveguide axis aligned with arm : if we define a plane with both the axis of frustum and axis of waveguide, thrust would be expected only in this plane of symmetry, if this plane is parallel to vertical axis of rotation it would come as a surprise that there is some measured thrust vector orthogonal to such plane of symmetry, by symmetry argument alone, regardless of possible mechanisms unless some very strong (and strange) kind of parity breaking, i.e. naming axis of frustum is X and waveguide is (roughly orthogonal) Y it's like measuring net thrust on Z, sorry for the clumsy wording...

Quote from: wembley on 07/25/2015 07:22 PMQuote from: Rodal on 07/25/2015 12:07 PMI'm concerned with the headline "EmDrive could reach Pluto in 18 months" being so at odds with what I heard was Prof. Tajmar's experimental data he had obtained a couple of months ago: Well, it might be that Prof Tajmar's setup had rather a low Q value, but this was not important as his test apparatus went down to sub-micronewton measurement.Did Tajmar ever say that his experimental results can be extrapolated to reach Pluto in 18 months using an EM Drive as the means of propulsion?

Quote from: Rodal on 07/25/2015 12:07 PMI'm concerned with the headline "EmDrive could reach Pluto in 18 months" being so at odds with what I heard was Prof. Tajmar's experimental data he had obtained a couple of months ago: Well, it might be that Prof Tajmar's setup had rather a low Q value, but this was not important as his test apparatus went down to sub-micronewton measurement.

I'm concerned with the headline "EmDrive could reach Pluto in 18 months" being so at odds with what I heard was Prof. Tajmar's experimental data he had obtained a couple of months ago:

Quote from: Rodal on 07/25/2015 07:53 PMQuote from: wembley on 07/25/2015 07:22 PMQuote from: Rodal on 07/25/2015 12:07 PMI'm concerned with the headline "EmDrive could reach Pluto in 18 months" being so at odds with what I heard was Prof. Tajmar's experimental data he had obtained a couple of months ago: Well, it might be that Prof Tajmar's setup had rather a low Q value, but this was not important as his test apparatus went down to sub-micronewton measurement.Did Tajmar ever say that his experimental results can be extrapolated to reach Pluto in 18 months using an EM Drive as the means of propulsion?No, that's from a NASA 0.4 model

Quote from: deltaMass on 07/25/2015 10:37 PMWith such small thrust and the apparatus not being self-contained, I am wary to break out any champagne here.Tajmar concludes:Quote from: Tajmar and FiedlerThe nature of the thrusts observed is still unclear. Additional tests need to be carried out to study the magnetic interaction of the power feeding lines used for the liquid metal contacts. Our test campaign can not confirm or refute the claims of the EMDrive but intends to independently assess possible side-effects in the measurements methods used so far This is the most lukewarm kind of support imaginable. Shawyer is encouraged by this ? ( http://www.wired.co.uk/news/archive/2015-07/24/emdrive-space-drive-pluto-mission )Quote from: Wired article The 'impossible' EmDrive could reach Pluto in 18 months Roger Shawyer is encouraged by Tajmar's work, which he says validates his own theoretical predictions as well as his experimental results. The authors state that they can not confirm or refute the claims of the EMDrive !!!!!(page 9 of Tajmar's report)If the authors themselves conclude that they cannot confirm or deny the EM Drive claims, there is nothing here for John Baez or Sean Carroll to have to respond to. All that Baez and Carroll have to do is to quote the authors saying that the authors accept that their report is inconclusive !

With such small thrust and the apparatus not being self-contained, I am wary to break out any champagne here.

The nature of the thrusts observed is still unclear. Additional tests need to be carried out to study the magnetic interaction of the power feeding lines used for the liquid metal contacts. Our test campaign can not confirm or refute the claims of the EMDrive but intends to independently assess possible side-effects in the measurements methods used so far

Roger Shawyer is encouraged by Tajmar's work, which he says validates his own theoretical predictions as well as his experimental results.

What I can't understand about Tajmar's build is he could have easily duplicated Shawyer's 1st Experimental EMDrive ...This Tajmar mini EMDrive is really a very strange build.

We would like to thank Roger Shawyer for his assistance

...As far as Tajmar can tell, Shawyer is 100% right. That's pretty strong support, IMO

It must be noted that Shawyers analysis and claims are highly controversial (e.g. Ref. 9) as this would obviously violate the conservation of momentum (pushing against itself) following his theory

Additional tests need to be carried out to study the magnetic interaction of the power feeding lines used for the liquid metal contacts. Our test campaign can not confirm or refute the claims of the EMDrive but intends to independently assess possible side-effects in the measurements methods used so far. Nevertheless, we do observe thrusts close to the magnitude of the actual predictions after eliminating many possible error sources that should warrant further investigation into the phenomena. Next steps include better magnetic shielding, further vacuum tests and improved EMDrive models with higher Q factors and electronics that allow tuning for optimal operation. As a worst case we may find how to effectively shield thrust balances from magnetic fields.

Quote Additional tests need to be carried out to study the magnetic interaction of the power feeding lines used for the liquid metal contacts. Our test campaign can not confirm or refute the claims of the EMDrive

Additional tests need to be carried out to study the magnetic interaction of the power feeding lines used for the liquid metal contacts. Our test campaign can not confirm or refute the claims of the EMDrive