I think that X-Ray, TheTraveller, Todd "WarpTech" got this right. The dimensions are off by a factor of 2.
The internal length is actually less than 2 times the length given (the length is given by the aspect ratio in the COMSOL FEA)
Let's hope someone who's reading the NSF do ask him tomorrow at the conference. Or even better, Martin Tajmar read this forum himself and get all the interesting stuff from this community brain
I show the calculated TE111 Electric Field in theta polar direction for Tajmar's TU Dresden University EM Drive, to compare it with his COMSOL FEA calculationAssumed dimensions:Big diameter = 0.1062 m = (2*0.0541m - 0.002 m)Small diameter = 0.075 m = (2*0.0385 m - 0.002 m)Axial Length = 0.100842 m = 0.735*2*0.0686 mAs per TheTraveller I have subtracted 2 mm for copper thickness from the external dimensions, however this has a negligible influence on the resultsThe axial internal length is 73.5% of the exterior length (it is adjusted internally with a screw prior to testing)TE111 Natural frequency = 2.446 GHzI enclose strictly for discussion, research and illustration purposes Fig. 2 a of Tajmar et.al. COMSOL FEA analysis for comparison with my calculations “…for purposes such as criticism, comment, news reporting, scholarship, or research…” under US Fair Usehttp://fairuse.stanford.edu/overview/fair-use/what-is-fair-use/This is the American Institute of Aeronautics and Astronautics link to Martin Tajmar's et.al. paper, that should be obtained from the American Institute of Aeronautics and Astronautics:Direct Thrust Measurements of an EM Drive and Evaluation of Possible Side-Effects M. Tajmar and G. Fiedler51st AIAA/SAE/ASEE Joint Propulsion Conference http://arc.aiaa.org/doi/pdf/10.2514/6.2015-4083
...But could you elaborate on why you think the length is also off by a factor of 2, i.e. that it should be less than 34.3 mm? If we assume that the big diameter is actually 108.2 mm, then a length of 68.6 mm seems to agree with the proportions in the COMSOL diagram.
Quote from: Rodal on 07/27/2015 06:00 pmI think that X-Ray, TheTraveller, Todd "WarpTech" got this right. The dimensions are off by a factor of 2. I'm not arguing about the other dimensions, only the length/height.I read your post several times, and each time I thought that your concern was that the length of the cavity could be adjusted between experiments because you emphasized the adjustable endplate. Hence my last post arguing that the length would be fixed for all runs after initial calibration. However, I now see that you were instead arguing that both the diameters AND the length must be off by a factor of two. My apologies for misinterpreting you.Quote from: Rodal on 07/26/2015 11:58 pmThe internal length is actually less than 2 times the length given (the length is given by the aspect ratio in the COMSOL FEA)But could you elaborate on why you think the length is also off by a factor of 2, i.e. that it should be less than 34.3 mm? If we assume that the big diameter is actually 108.2 mm, then a length of 68.6 mm seems to agree with the proportions in the COMSOL diagram.
Quote from: cej on 07/27/2015 07:10 pmQuote from: Rodal on 07/27/2015 06:00 pmI think that X-Ray, TheTraveller, Todd "WarpTech" got this right. The dimensions are off by a factor of 2. I'm not arguing about the other dimensions, only the length/height.I read your post several times, and each time I thought that your concern was that the length of the cavity could be adjusted between experiments because you emphasized the adjustable endplate. Hence my last post arguing that the length would be fixed for all runs after initial calibration. However, I now see that you were instead arguing that both the diameters AND the length must be off by a factor of two. My apologies for misinterpreting you.Quote from: Rodal on 07/26/2015 11:58 pmThe internal length is actually less than 2 times the length given (the length is given by the aspect ratio in the COMSOL FEA)But could you elaborate on why you think the length is also off by a factor of 2, i.e. that it should be less than 34.3 mm? If we assume that the big diameter is actually 108.2 mm, then a length of 68.6 mm seems to agree with the proportions in the COMSOL diagram.The WR340 wave guide feeding it is 138 mm, therefore, it can't be 68.6mm tall. It must be twice as tall as what was reported. I'd bet they measured 68.6 mm from the origin of coordinates, at the center of the frustum.
The Chinese are very quick to capitalise on new stuff. They also have someone who claims to have the best performance figure ever recorded for a frustum.And yet...
Ref. 9 Costello, J.P., "Why Shawyer’s ‘electromagnetic relativity drive’ is a fraud",http://johncostella.webs.com/shawyerfraud.pdf(Accessed 5th July 2015)
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
So if you or one of your friends within that 50 mile radius want to put a couple bucks to help not to make more millions but because they choose to dream, I'll welcome it.Shell
Quote from: WarpTech on 07/27/2015 07:25 pmQuote from: cej on 07/27/2015 07:10 pmQuote from: Rodal on 07/27/2015 06:00 pmI think that X-Ray, TheTraveller, Todd "WarpTech" got this right. The dimensions are off by a factor of 2. I'm not arguing about the other dimensions, only the length/height.I read your post several times, and each time I thought that your concern was that the length of the cavity could be adjusted between experiments because you emphasized the adjustable endplate. Hence my last post arguing that the length would be fixed for all runs after initial calibration. However, I now see that you were instead arguing that both the diameters AND the length must be off by a factor of two. My apologies for misinterpreting you.Quote from: Rodal on 07/26/2015 11:58 pmThe internal length is actually less than 2 times the length given (the length is given by the aspect ratio in the COMSOL FEA)But could you elaborate on why you think the length is also off by a factor of 2, i.e. that it should be less than 34.3 mm? If we assume that the big diameter is actually 108.2 mm, then a length of 68.6 mm seems to agree with the proportions in the COMSOL diagram.The WR340 wave guide feeding it is 138 mm, therefore, it can't be 68.6mm tall. It must be twice as tall as what was reported. I'd bet they measured 68.6 mm from the origin of coordinates, at the center of the frustum.But note that 68.6 mm times 2 is only 137.2 mm, still short even though very close.
At least an explanation exists for why the Chinese don't already have production lines for churning out EmDrives. Can there be any other excuse?
Quote from: deltaMass on 07/27/2015 07:59 pmAt least an explanation exists for why the Chinese don't already have production lines for churning out EmDrives. Can there be any other excuse?Lack of power at ground level. Lack of millions of potential buyers. Translation; lack of market.
Which are not a problem for the well-funded Chinese [..] Space Program.
Quote from: rfmwguy on 07/27/2015 08:55 pmQuote from: deltaMass on 07/27/2015 07:59 pmAt least an explanation exists for why the Chinese don't already have production lines for churning out EmDrives. Can there be any other excuse?Lack of power at ground level. Lack of millions of potential buyers. Translation; lack of market.Which are not a problem for the well-funded Chinese Air Force and Space Program. Lack of a market has not impeded their on-going Taikonaut and Mini-Space Station programs, Space Defense tests, as well as their long-term programs including ion-drives and Moon program. So, why no deployment of the Yang EM Drive in Space, if it can really do what is claimed?
Quote from: mittelhauser on 07/27/2015 05:06 pmQuote from: TheTraveller on 07/27/2015 06:58 amQuote from: demofsky on 07/27/2015 06:30 amThe device used by Tajmar looks more like a version of Shawyer's first fustrum than the latest work by Yang, et al. It would be very nice if we could get actual schematics of Tajmar's fustrum rather than squinting at pictures trying to figure out what he did...Yes I agree it is very the Experimental EMDrive except Shawyer got 16mNs out of his. It took him several years to get it right. Q was 5,900 but that was because it had a dielectric inside. He used 5 magnetrons, burnt out 3 and burned a hole in a waveguide. But he got there. His experimental data was verified by a expert Uk aerospace industry group set up by the UK gov Dept of Defense. After the experts gave him the thumbs up, the UK gov gave him the 1st grant to build the Demonstrator EMDrive and the rotary test rig.After the UK gov again verified the data from the Demonstrator trials he got the final payment from the UK gov.Sigh. I'll try one more time. You keep making these statements over and over. However, you have provided no evidence to support those statements. Who were the experts who "verified" it? Where is a document which shows what was verified? Etc, etc. You promised us a paper which would end all doubts and all that was produced was an old paper which didn't have any new experimental data. I *really* want to be a believer and you make it extremely difficult. I'll say once again, stop posting blindly optimistic projections and focus on your build and get some data which can be independently verified and which shows what you claim...Please! I'm wishing you luck.Frankly, if this had been truly verified at the levels you imply, funding wouldn't be an issue and folks wouldn't be scrambling to do FundMe's for DIY versions. I sit within 50 miles of a LOT of people who would happily throw millions at the project if there was evidence such as you keep insisting already exists.Here is a builder who isn't either way, I'm an engineer who can be optimistic, but in the end I rely on data. I've seen some proof in NASA's EagleWorks and in the current tests which are verified. The Chinese could be questioned if you want.There are many things that could lead to aberrations in thrust, I'll agree in that point, but what's interesting, each test is a little different with different jigs to test, different power, different cavities, different sizes, in vacuum or not and the list is quite extensive. The few things in all of those that have reported thrust (verified or not) is that have is they injected microwaves into a resonate conical enclosed cavity and thrust was measured. I have looked for the common ingredient other than those I just listed and there doesn't seem to be one at all. I'm not alone, as there are very sharp skeptics picking it apart.It's good enough for me to take what little I got from gofundme and my own pocket and pick apart this bit by bit test by test to get to a truth in why this simple device has confounded some of the finest minds around. Answers are not going to take millions but a well designed tests could for a few thousand. When I'm over and done and have solid answers and maybe the key, I'll share it. So if you or one of your friends within that 50 mile radius want to put a couple bucks to help not to make more millions but because they choose to dream, I'll welcome it.Shell
Quote from: TheTraveller on 07/27/2015 06:58 amQuote from: demofsky on 07/27/2015 06:30 amThe device used by Tajmar looks more like a version of Shawyer's first fustrum than the latest work by Yang, et al. It would be very nice if we could get actual schematics of Tajmar's fustrum rather than squinting at pictures trying to figure out what he did...Yes I agree it is very the Experimental EMDrive except Shawyer got 16mNs out of his. It took him several years to get it right. Q was 5,900 but that was because it had a dielectric inside. He used 5 magnetrons, burnt out 3 and burned a hole in a waveguide. But he got there. His experimental data was verified by a expert Uk aerospace industry group set up by the UK gov Dept of Defense. After the experts gave him the thumbs up, the UK gov gave him the 1st grant to build the Demonstrator EMDrive and the rotary test rig.After the UK gov again verified the data from the Demonstrator trials he got the final payment from the UK gov.Sigh. I'll try one more time. You keep making these statements over and over. However, you have provided no evidence to support those statements. Who were the experts who "verified" it? Where is a document which shows what was verified? Etc, etc. You promised us a paper which would end all doubts and all that was produced was an old paper which didn't have any new experimental data. I *really* want to be a believer and you make it extremely difficult. I'll say once again, stop posting blindly optimistic projections and focus on your build and get some data which can be independently verified and which shows what you claim...Please! I'm wishing you luck.Frankly, if this had been truly verified at the levels you imply, funding wouldn't be an issue and folks wouldn't be scrambling to do FundMe's for DIY versions. I sit within 50 miles of a LOT of people who would happily throw millions at the project if there was evidence such as you keep insisting already exists.
Quote from: demofsky on 07/27/2015 06:30 amThe device used by Tajmar looks more like a version of Shawyer's first fustrum than the latest work by Yang, et al. It would be very nice if we could get actual schematics of Tajmar's fustrum rather than squinting at pictures trying to figure out what he did...Yes I agree it is very the Experimental EMDrive except Shawyer got 16mNs out of his. It took him several years to get it right. Q was 5,900 but that was because it had a dielectric inside. He used 5 magnetrons, burnt out 3 and burned a hole in a waveguide. But he got there. His experimental data was verified by a expert Uk aerospace industry group set up by the UK gov Dept of Defense. After the experts gave him the thumbs up, the UK gov gave him the 1st grant to build the Demonstrator EMDrive and the rotary test rig.After the UK gov again verified the data from the Demonstrator trials he got the final payment from the UK gov.
The device used by Tajmar looks more like a version of Shawyer's first fustrum than the latest work by Yang, et al. It would be very nice if we could get actual schematics of Tajmar's fustrum rather than squinting at pictures trying to figure out what he did...
Hey look, someone actually talking about space on this thread.Quote from: Rodal on 07/27/2015 09:10 pmWhich are not a problem for the well-funded Chinese [..] Space Program.What makes you think it's well funded? Last I heard, the best estimates put it below ESA.. i.e., about a third of the US program.
Quote from: TheTraveller on 07/26/2015 06:13 amQuote from: birchoff on 07/26/2015 02:12 am@Rodal or anyone for that matter know how to calculate shawyer's design factor?Shawyer's Df equation is attached. Have verified with Shawyer that it is correct.Writing x0,x1,x2 for the 3 lambdas, this can be expressed as D = [(1-a)/sqrt(a)] * [sqrt(b)/(1-b)], where a = x1/x2, b = x02/(x1*x2)Notice that D is a separable function of a,b and so can be readily optimised by inspection.Dmax -> infinity when a->0 and/or b->1.Do other relations between x0,1,2 exist to prevent D becoming infinite?Obviously if a > 0 and b < 1 then Dmax when a is min, b is max
Quote from: birchoff on 07/26/2015 02:12 am@Rodal or anyone for that matter know how to calculate shawyer's design factor?Shawyer's Df equation is attached. Have verified with Shawyer that it is correct.
@Rodal or anyone for that matter know how to calculate shawyer's design factor?