With all the fooling I've done with meep recently, I discovered a new trick. I can show different views of slices of a 4-D data set. Here is the closed cavity with the Gaussian drive frequency centered at 2.253 GHz though Meep/Harminv says it resonates at 2.343 GHz. These are all at timestep 1420. What mode is this illustrated.Shown are big end, center and small end slices "x", and y and z axial slices.
I have a more general question about the evolution of all this research.According to Shawyer, we have to increase the Q factor up to billions in order to scale the thrust (with the help of superconducting cavities). Hence Shawyer envisioned not only thrusters for spaceprobes and spaceships, but also "lift engines" here on Earth, with -literally speaking- flyings cars and the like around the corner. If Shawyer is wrong regarding the scale law of thrust vs Q (and the lack of published experimental results of superconducting EmDrives up to now would bolster this pessimistic view), but the EmDrive is still real, would the thrust stay very low even with high power, restricting the applications to space-based thrusters only? If an alternate model is right, for example Todd's: wavelength attenuation produces thrust in a refractive index gradient, due to an energy density unevenly distributed thanks to a proper asymmetric geometry aka the frustum: the thrust is then maximized while increasing the attenuation, and not increasing the energy stored into the cavity via the Q factor (the "tug of war" between attenuated energy and stored energy).If this model is right, according to you WarpTech, would the max. thrust be caped well below one gee, or do you think your model could enable lift-engines in Earth gravity field, with enough power on board? (powerful still cheap and light energy source, I'm not speaking of fitting a nuclear power plant in a car…)
Quote from: Rodal on 06/15/2015 02:05 amQuote from: TheTraveller on 06/15/2015 01:22 amWE HAVE RESONANCE!Attached is TE01x analysis for the Baby EM Drive.With flat end plates, length resonance can occur anywhere from the min spacing of:1) centre of big end plate to centre of small end plateto max spacing of :2) outer edge big end plate to outer edge small end plate.As you can see TE013 generates a length resonance ring just inside the maximal outer edge spacing.For the Baby EM Drive, there are several resonance modes. Which is driven depends on excitation method, antenna placement and antenna design.Spreadsheet attached.I get TE013 for Baby EM Drive with my exact solution at a frequency of 24.34 GHz. There are many other natural frequencies close by though, so there will be participation from other modes as well.I imagine that it is not a coincidence that TE013 is the natural frequency that matches their excitation frequency. TE01p has been the preferred mode of excitation of both Shawyer for the Demo and the Flight Thruster, and by Prof. Yang, and it was also the mode shape that gave the highest Force/InputPower for NASA Eagleworks (see http://emdrive.wiki/Experimental_Results ), so it looks to me that the fellows at Aachen calculated this before they machined Baby EM Drive. These guys did their homework The end plates of the Baby EM Drive are flat, so a lot of close frequencies should obtain resonance. For your 24.34GHz spherical end plate case, the results are attached, which show resonance a bit further away from the side wall but not at the minimal centre to centre end plate spacing.Would expect thrust to be MUCH greater with spherical and plates as much more (should be all of it) end plate surface area is working at resonance as against a thin ring (very small area) at each end plate.
Quote from: TheTraveller on 06/15/2015 01:22 amWE HAVE RESONANCE!Attached is TE01x analysis for the Baby EM Drive.With flat end plates, length resonance can occur anywhere from the min spacing of:1) centre of big end plate to centre of small end plateto max spacing of :2) outer edge big end plate to outer edge small end plate.As you can see TE013 generates a length resonance ring just inside the maximal outer edge spacing.For the Baby EM Drive, there are several resonance modes. Which is driven depends on excitation method, antenna placement and antenna design.Spreadsheet attached.I get TE013 for Baby EM Drive with my exact solution at a frequency of 24.34 GHz. There are many other natural frequencies close by though, so there will be participation from other modes as well.I imagine that it is not a coincidence that TE013 is the natural frequency that matches their excitation frequency. TE01p has been the preferred mode of excitation of both Shawyer for the Demo and the Flight Thruster, and by Prof. Yang, and it was also the mode shape that gave the highest Force/InputPower for NASA Eagleworks (see http://emdrive.wiki/Experimental_Results ), so it looks to me that the fellows at Aachen calculated this before they machined Baby EM Drive. These guys did their homework
WE HAVE RESONANCE!Attached is TE01x analysis for the Baby EM Drive.With flat end plates, length resonance can occur anywhere from the min spacing of:1) centre of big end plate to centre of small end plateto max spacing of :2) outer edge big end plate to outer edge small end plate.As you can see TE013 generates a length resonance ring just inside the maximal outer edge spacing.For the Baby EM Drive, there are several resonance modes. Which is driven depends on excitation method, antenna placement and antenna design.Spreadsheet attached.
we profanes are in need of an update in a while! I see lots of work is going on and I am impressed on the role this forum is having, but unfortunately I can't follow much of developments...how the new experiments are going?
.....I calculated the natural frequency of the EM Drive based on the formula for a perfect cylinder ( https://en.wikipedia.org/wiki/Microwave_cavity#Cylindrical_cavity ) (using the cylindrical Bessel functions that you use in your spreadsheet), based on the Mean diameter (the average of the small and big diameters of the Baby EM Drive), I obtained the following frequency for TE013 for perfectly flat ends:24.41 GHzwhich compares to the value I obtained using my exact solution:24.34 GHz......
Quote from: Rodal on 06/15/2015 12:38 pm.....I calculated the natural frequency of the EM Drive based on the formula for a perfect cylinder ( https://en.wikipedia.org/wiki/Microwave_cavity#Cylindrical_cavity ) (using the cylindrical Bessel functions that you use in your spreadsheet), based on the Mean diameter (the average of the small and big diameters of the Baby EM Drive), I obtained the following frequency for TE013 for perfectly flat ends:24.41 GHzwhich compares to the value I obtained using my exact solution:24.34 GHz......With respect that is not now effective guide wavelength is calculated. Roger Shawyer told me how to do it and I shared this here several times. It is in my SS.The effective guide wavelength is not based on the average of the 2 end plate diameter. It is the numerically integrated value of 10,000 diameters (well I use 10,000, could be more, could be less) including and in between the plates.For the Baby EMD the guide wavelength for the mean/average diameter is = 0.016501. The numerically integrated effective guide wavelength is = 0.018224, which is why your resonance is too high as your effective guide wavelength is too small.Have attached the latest version of the SS, which has a new feature.
Quote from: TheTraveller on 06/15/2015 02:28 pmQuote from: Rodal on 06/15/2015 12:38 pm.....I calculated the natural frequency of the EM Drive based on the formula for a perfect cylinder ( https://en.wikipedia.org/wiki/Microwave_cavity#Cylindrical_cavity ) (using the cylindrical Bessel functions that you use in your spreadsheet), based on the Mean diameter (the average of the small and big diameters of the Baby EM Drive), I obtained the following frequency for TE013 for perfectly flat ends:24.41 GHzwhich compares to the value I obtained using my exact solution:24.34 GHz......With respect that is not now effective guide wavelength is calculated. Roger Shawyer told me how to do it and I shared this here several times. It is in my SS.The effective guide wavelength is not based on the average of the 2 end plate diameter. It is the numerically integrated value of 10,000 diameters (well I use 10,000, could be more, could be less) including and in between the plates.For the Baby EMD the guide wavelength for the mean/average diameter is = 0.016501. The numerically integrated effective guide wavelength is = 0.018224, which is why your resonance is too high as your effective guide wavelength is too small.Have attached the latest version of the SS, which has a new feature.Let's agree to disagree on this point otherwise this is going to run for ever. You calculate the effective guide wavelength and the cut-off based on Bessel cylinder functions that do not satisfy the boundary conditions of the problem. It is an ad-hoc solution that you like because it agrees with Shawyer's formulation .My point was that there is no justification to include so many digits of numerical precision based on an ad-hoc formula based on cylinder functions and geometrical dimensions (runout, concentricity) of unknown precision, and not performing a spectrum solution, as the participation of other modes in the response is not taken into account (the response of any system will not be the response of a single mode, but will include other mode shapes as well).
It is not what I like or not. It is now Roger Shawyer instructed me to calculate the effective guide wavelength.It is your method which does not agree with how Roger Shawyer and SPR do the effective guide wavelength calculation.
Quote from: TheTraveller on 06/15/2015 02:45 pmIt is not what I like or not. It is now Roger Shawyer instructed me to calculate the effective guide wavelength.It is your method which does not agree with how Roger Shawyer and SPR do the effective guide wavelength calculation.Is there a numerical reason to believe that the SPR method delivers superior results to Rodal's?
I think that there should be a separate thread that can be commented on ONLY by the people at Eagleworks for the purpose of information dissemination.
Quote from: inquisitive-j on 06/15/2015 02:51 pmI think that there should be a separate thread that can be commented on ONLY by the people at Eagleworks for the purpose of information dissemination.Has anyone from Eagleworks other than Paul March (NSF user Star-Drive) posted here?All his posts an be seen here. His last post was on 2015-04-30, the day after NSF's Evaluating NASA’s Futuristic EM Drive feature article was published.~Kirk
Quote from: inquisitive-j on 06/15/2015 02:51 pmI think that there should be a separate thread that can be commented on ONLY by the people at Eagleworks for the purpose of information dissemination.Has anyone from Eagleworks other than Paul March (NSF user Star-Drive) posted here?All his posts can be seen here. His last post was on 2015-04-30, the day after NSF's Evaluating NASA’s Futuristic EM Drive feature article was published.~KirkEdit: Typo
Quote from: kdhilliard on 06/15/2015 03:02 pmQuote from: inquisitive-j on 06/15/2015 02:51 pmI think that there should be a separate thread that can be commented on ONLY by the people at Eagleworks for the purpose of information dissemination.Has anyone from Eagleworks other than Paul March (NSF user Star-Drive) posted here?All his posts can be seen here. His last post was on 2015-04-30, the day after NSF's Evaluating NASA’s Futuristic EM Drive feature article was published.~KirkEdit: TypoAll that can be said is that for the moment there is no posts from that direction, and not likely to be for the time being so the OP's suggestion is something of a non-starter.@TheTraveller first I've heard of that.:eek:
Has anyone from Eagleworks other than Paul March (NSF user Star-Drive) posted here?All his posts can be seen here. His last post was on 2015-04-30, the day after NSF's Evaluating NASA’s Futuristic EM Drive feature article was published.~KirkEdit: Typo
Quote from: kdhilliard on 06/15/2015 03:02 pmHas anyone from Eagleworks other than Paul March (NSF user Star-Drive) posted here?All his posts can be seen here. His last post was on 2015-04-30, the day after NSF's Evaluating NASA’s Futuristic EM Drive feature article was published.~KirkEdit: TypoI'm not sure. Paul March was the person I had in mind the most when I was posting that. I didn't think to look at his profile for a complete list of posts. I also didn't realize that he posted so little outside of emDrive discussion. I was hoping that he had posted in the 2-3 months that I'd been away from the threads, but I suppose not.