...An interesting effect for sure.My point was what Todd was claiming files in the face of how radiation pressure works, which is there will be no radiation pressure on a surface, from a EM wave, that is orthogonal to a reflecting surface, which is what Shawyer claims and was backed up by the peer reviewers.
@SeaShellsI don’t know if you are still having doubts about your current frustum design. If I don’t read for a couple days it takes me a week to catch up, so your feelings may have completely changed since I last read about your frustrations. Regardless, I would like for you to know, I for one am very excited to see your experimental results exactly as they have been outlined. Your current frustum design may give us valuable information. One can not know until the experiment has been run and the data collected and analyzed what the optimal configuration is for an unknown effect, regardless of simulations (that may very well be leaving out the most important variables). Your set up allows for different antenna designs/placements and different cavity lengths with a solid testing platform eliminating (or reducing below noise level) most air thermal effects* and external EM coupling. After the first series of tests, you can then run another (otherwise identical) test group on a similar frustum, changing only the cone half angle. The experience gained from building the first should make building a second a breeze. I expect data from all these different experiments should give EXCELLENT information to help narrow the focus of theory efforts. Who knows, your smaller cone angle could give the largest thrust. Wouldn’t that be a kick. *We don’t know what effect air may have. Perforation may be deleterious to the “real” effect (if it exists).
Quote from: TheTraveller on 08/04/2015 08:42 am...An interesting effect for sure.My point was what Todd was claiming files in the face of how radiation pressure works, which is there will be no radiation pressure on a surface, from a EM wave, that is orthogonal to a reflecting surface, which is what Shawyer claims and was backed up by the peer reviewers.You are failing to distinguish between the physical problem of a confined wave and a free wave.To fix your ideas: think of the difference between fluid flow inside a venturi pipe (you clearly have pressure on the inner surfaces of the pipe) and the flow of a water jet tangent to a rigid surface, with the other surface of the fluid jet having a free surface.The problem of radiation pressure of a free wave orthogonal to a surface ("solar sail") and tangent to the surface is different from the problem at hand. You have to analyze the problem mathematically and solve the boundary conditions of the problem: you have a photon gas inside the frustum.
Quote from: TheTraveller on 08/04/2015 08:42 am...An interesting effect for sure.My point was what Todd was claiming files in the face of how radiation pressure works, which is there will be no radiation pressure on a surface, from a EM wave, that is orthogonal to a reflecting surface, which is what Shawyer claims and was backed up by the peer reviewers.You are failing to distinguish between the physical problem of a confined wave and a free wave.To fix your ideas: think of the difference between fluid flow inside a venturi pipe (you clearly have pressure on the inner surfaces of the pipe) and the flow of a water jet tangent to a rigid surface, with the other surface of the fluid jet having a free surface (the free surface of the fluid jet is unconfined, and therefore its pressure is not higher than ambient pressure).The problem of radiation pressure of a free wave orthogonal to a surface ("solar sail") and tangent to the surface is different from the problem at hand. You have to analyze the problem mathematically and solve the boundary conditions of the problem: you have a photon gas inside the frustum. The inner surfaces of the frustrum confine the electromagnetic fields inside the frustum hence there is pressure against all internal surfaces.
A gas is a compressible fluid and as such describable by fluid dynamics, just a different constitutive law. Different fluids have different constitutive laws.
REF and Quote... https://en.wikipedia.org/wiki/Evanescent_waveShell
Thermal tests done including 5 minute run at 30% power, which is what I'll use for fulcrum test. What I learned: Matching into frustum is good, magnetron ran at temperatures well below 200°C. Still had minor arcing, corrected it with full teardown and replacement of Db with mesh only, no copper clad. IOW, frustum is now all mesh except for Ds where magnetron is mounted. There was no arcing on Ds throughout any thermal testing. Plasma focused on Db, interestingly enough diagonally across from radome, not directly across axially.Here's the video, time to do yard work, oh joy:
We are calculating frequencies based on different geometrical dimensions.
Quote from: SeeShells on 08/04/2015 01:16 pm REF and Quote... https://en.wikipedia.org/wiki/Evanescent_waveShellInside a solid copper EMDrive, designed to follow Shawyer's dimensional recommendations, there are no Evanescent waves as the small end operates above cutoff.This is not to say do not experiment with creating internal frustum dimensional, mode and external frequency situations that will create internal Evanescent waves at the small end.What the SPR advise says is that in their experience, operation of the small end at or below cutoff and creating Evanescent waves will result in no significant resonance and no significant Force generation.Your mileage may vary.
Quote from: TheTraveller on 08/04/2015 03:41 pmQuote from: SeeShells on 08/04/2015 01:16 pm REF and Quote... https://en.wikipedia.org/wiki/Evanescent_waveShellInside a solid copper EMDrive, designed to follow Shawyer's dimensional recommendations, there are no Evanescent waves as the small end operates above cutoff.This is not to say do not experiment with creating internal frustum dimensional, mode and external frequency situations that will create internal Evanescent waves at the small end.What the SPR advise says is that in their experience, operation of the small end at or below cutoff and creating Evanescent waves will result in no significant resonance and no significant Force generation.Your mileage may vary.Interesting TT because the tapered cavity induces by its shape wave and mode decay. https://en.wikipedia.org/wiki/Evanescent_wave#/media/File:Electron_density_wave_-_plasmon_excitations.pngThe traveling and mode decay are evanescent waves.
FYIhttp://arxiv.org/pdf/1507.05828.pdfhttp://arXive.org/pdf/1311.1095.pdf
Quote from: Notsosureofit on 08/04/2015 04:21 pmFYIhttp://arxiv.org/pdf/1507.05828.pdfhttp://arXive.org/pdf/1311.1095.pdf2nd link is dead
I won't waste my time in calculating the exact number based on your definition of length since from your answer it is evident that you don't care, and I have better things to do.