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#140 by Bob Woods on 30 Aug, 2016 23:54
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Anyone know what would be the effect if the ends of Emdrive, instead of flat surfaces, were semi spherical ?
Both Shawyer and The Traveler have strongly recommended that the frustum ends be spherical to improve efficiency. To date the DIY folks have mostly used flat ends because it is easier and less costly if your goal is to just see any force.
The threads here are long with some exceptional discussions going on covering a vast array of information and theory. They are actually quite remarkable. It takes a lot of work but I would suggest you start skimming them around the end of March 2015. -
#141 by mwvp on 31 Aug, 2016 01:13
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Anyone know what would be the effect if the ends of Emdrive, instead of flat surfaces, were semi spherical ?
The bandwidth of the frustum decreases while increasing the resonance within the narrower range (increased q-factor). In Q-factor dependent theories, this should increase the measured thrust for a given center frequency.
My intuition tells me the orthodoxy here of using the ray-tracing concave at apex and base is misguided. I believe fields vs. photons is the approach most optimally taken.
IMHO Higher Q will be realized by using convex at apex and concave at base reflection plates. Sharp, high-divergence bends result in high impedance to currents, hence loss. I would like to see an optimization of Q vs. dispersion for a resonator. Comsol I know can do this.
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#142 by SeeShells on 31 Aug, 2016 01:22
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Anyone know what would be the effect if the ends of Emdrive, instead of flat surfaces, were semi spherical ?
Hi Johnathan, drive builder here. I'm going to try to jump in here for a bit as you are asking honest questions.
Typically you can see an increase of around 6db by using semi-spherical ends although that is just in the Q.
This is a sweep in FEKO done by Monomorphic of one of my cavities with curved endplates that make give you a feel for what's happening. 2.40GHz > 2.42GHz loop driven sidewall.
Shell
https://www.youtube.com/watch?v=WBhlFBjJDvo&feature=youtu.be
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#143 by SeeShells on 31 Aug, 2016 01:24
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Love your brain!Anyone know what would be the effect if the ends of Emdrive, instead of flat surfaces, were semi spherical ?
The bandwidth of the frustum decreases while increasing the resonance within the narrower range (increased q-factor). In Q-factor dependent theories, this should increase the measured thrust for a given center frequency.
My intuition tells me the orthodoxy here of using the ray-tracing concave at apex and base is misguided. I believe fields vs. photons is the approach most optimally taken.
IMHO Higher Q will be realized by using convex at apex and concave at base reflection plates. Sharp, high-divergence bends result in high impedance to currents, hence loss. I would like to see an optimization of Q vs. dispersion for a resonator. Comsol I know can do this.
Very true look at the sim I just posted and you'll notice that the small endplate isn't curved.
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#144 by johnatan warp drive on 31 Aug, 2016 02:04
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Thanks for the suggestions
If this idea is promising, can yield a scholarship at MIT kkk
To improve efficiency , it would be something like this (Attachment) ?
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#145 by SeeShells on 31 Aug, 2016 02:11
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Thanks for the suggestions
This is easier to understand and see.
If this idea is promising, can yield a scholarship at MIT kkk
To improve efficiency , it would be something like this (Attachment) ?
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#146 by meekGee on 31 Aug, 2016 05:02
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Well there is the problem:
Thrust without exhaust is of course impossible.
So lets avoid consideration that the EmDrive gained momentum is at the expense of EM wave lost momentum as the internal EM wave experiences red shift from lost EM wave momentum.
Debate this all you wish as I will not engage until my data is ready to be published.
Why would that be?
Momentum can be conserved without thrust.
When I fall towards Earth, there's no exhaust, but Earth compensates by falling just a little bit towards me.
If this magic drive somehow make the entire mass in the universe accelerate opposite of the ship, then it's fine. Or maybe every particle in the universe, in some proportion to its distance, so nearer particles get more "tug".
I'm not attempting to explain the EM drive, just to say that "exhaust-less" is not the same as "reaction-less".
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#147 by A_M_Swallow on 31 Aug, 2016 05:17
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Well there is the problem:
Thrust without exhaust is of course impossible.
So lets avoid consideration that the EmDrive gained momentum is at the expense of EM wave lost momentum as the internal EM wave experiences red shift from lost EM wave momentum.
Debate this all you wish as I will not engage until my data is ready to be published.
Why would that be?
Momentum can be conserved without thrust.
When I fall towards Earth, there's no exhaust, but Earth compensates by falling just a little bit towards me.
If this magic drive somehow make the entire mass in the universe accelerate opposite of the ship, then it's fine. Or maybe every particle in the universe, in some proportion to its distance, so nearer particles get more "tug".
I'm not attempting to explain the EM drive, just to say that "exhaust-less" is not the same as "reaction-less".
For the test drives the walls of the room could be the mass that moves in the opposite direction. We can barely detect the force on the drive let alone the force on walls fastened to the ground. -
#148 by meekGee on 31 Aug, 2016 06:46
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Right, and for space drive applications, it could be tugging on the sun or the Oort cloud for all I know. In theory.Well there is the problem:
Thrust without exhaust is of course impossible.
So lets avoid consideration that the EmDrive gained momentum is at the expense of EM wave lost momentum as the internal EM wave experiences red shift from lost EM wave momentum.
Debate this all you wish as I will not engage until my data is ready to be published.
Why would that be?
Momentum can be conserved without thrust.
When I fall towards Earth, there's no exhaust, but Earth compensates by falling just a little bit towards me.
If this magic drive somehow make the entire mass in the universe accelerate opposite of the ship, then it's fine. Or maybe every particle in the universe, in some proportion to its distance, so nearer particles get more "tug".
I'm not attempting to explain the EM drive, just to say that "exhaust-less" is not the same as "reaction-less".
For the test drives the walls of the room could be the mass that moves in the opposite direction. We can barely detect the force on the drive let alone the force on walls fastened to the ground.
Just want to get the exhaust-less thing out of the way.
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#149 by bauhaus on 31 Aug, 2016 07:04
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Congrats. I am an anti-skeptic(Marcello Truzzi) when it comes to scientific breakthroughs however, Dr. Shawyer's presentation seems to claim that when the superconducting features are added to the em drive then thrust will be increased by orders of magnitude. So can someone knowledgeable explain to me why those testing the device don't just use a version that incorporates superconducting features? Is it that its so much more expensive? Is part of the problem here funding, as in few people are willing to even spend the money to test a device or scale up the size of the device so that it can clearly be shown to work or not?
2. Also, assuming it does not produce much thrust isn't it true that even at some minimal thrust x, the device will go into production and just scaled up as solar powered thrust on a satellite needing no propellant is so much better than just plain old thrust requiring propellant? Solar power for satellites will likely get cheaper and more powerful each year into the future. -
#150 by 1 on 31 Aug, 2016 07:30
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Anyone know what would be the effect if the ends of Emdrive, instead of flat surfaces, were semi spherical ?
The bandwidth of the frustum decreases while increasing the resonance within the narrower range (increased q-factor). In Q-factor dependent theories, this should increase the measured thrust for a given center frequency.
My intuition tells me the orthodoxy here of using the ray-tracing concave at apex and base is misguided. I believe fields vs. photons is the approach most optimally taken.
IMHO Higher Q will be realized by using convex at apex and concave at base reflection plates. Sharp, high-divergence bends result in high impedance to currents, hence loss. I would like to see an optimization of Q vs. dispersion for a resonator. Comsol I know can do this.
Loosely speaking, the way to increase Q is to set your cavity such that resonance occurs only at a single, 'pure' frequency rather than a base frequency + a(n infinite ) series of higher order harmonics. Again loosely speaking, this occurs when your cavity and your resonating fields 'belong' to one chosen coordinate system.
What does that mean?
Well, consider a cube. If your cavity is a cube, you'll have 'pure' resonance solutions in cartesian coordinates (x,y,z). Injecting, say, a single rectangular plane wave can cause a strong resonance if the frequency of that wave is well-chosen. Consider now an cylinder. This cavity will have 'pure' solutions expressed using bessel/hankle functions. If you excite the cavity with such, then you can again get strong resonance. If, however, you attempt to excite the cylindrical cavity with a rectangular plane wave (or vice-versa), then you'll have a mis-match between your wave and your cavity, and the malformed wave is then forced to convert into a form that matches the cavity. In layman's terms, this manifests as your original wave breaking into multiple different waves; spreading your energy out among multiple frequencies and modes. If you want a high Q (single, pure mode) this is bad. Therefore, one should chose a wave that matches the cavity.
The problem with a flat-ended frustum is that the cavity itself mixes coordinate systems. Flat endplates are very cartesian, however the curved wall is actually best thought of as a truncated cone, which belongs in the spherical coordinate domain. As such, the resonant modes in the cavity are never quite pure. A well designed setup can still produce good data, but you're always losing energy to this back and forth conversion game. Using curved endplates, such that the cavity geometry becomes a truncated spherical cone, restores the 'pureness' of the setup; and thus much higher Q factors can be achieved.
Well, at least theoretically. Engineering is pretty much the study of getting something built well enough to work as an optimal solution may not actually exist. It's the study of intelligent trade-offs and compormises. High Q is desirable. It's also more difficult to tune, more difficult to build, and more dependent on the rest of your hardware working near-perfectly. If a high-Q frustum falls out of resonance, it's going to fall fast and hard. Flat end plates are easier to work with; and won't bankrupt the home-builders here who are funding their own experiments out of pocket. (At least not as quickly. Some of the guys here are getting pretty into this: I half expect to see a vacuum chamber pop up here soon!)
For the more mathematically inclined, a good treatment is found here regarding closed form solutions to a truncates spherical cone. http://gregegan.customer.netspace.net.au/SCIENCE/Cavity/Cavity.html I don't remember seeing this posted before, but I'd be very surprised if it hasn't been; all company considered.
The main takeaway from that page is that the sharp curves of the corners can often be rendered insignificant if one choses a (pure!) resonant mode such that the corners are null regions in your standing waves. Scroll down about 3/4 of the way through that page to the "Current, Heating, and Q factors" section and look at the differences in some of the TM shapes. In this case, I believe the benefit to gentle corners would be vastly outweighed by the loss of Q in some of these more exotic cavity shapes.
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#151 by Chrochne on 31 Aug, 2016 08:19
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Congrats. I am an anti-skeptic(Marcello Truzzi) when it comes to scientific breakthroughs however, Dr. Shawyer's presentation seems to claim that when the superconducting features are added to the em drive then thrust will be increased by orders of magnitude. So can someone knowledgeable explain to me why those testing the device don't just use a version that incorporates superconducting features? Is it that its so much more expensive? Is part of the problem here funding, as in few people are willing to even spend the money to test a device or scale up the size of the device so that it can clearly be shown to work or not?
2. Also, assuming it does not produce much thrust isn't it true that even at some minimal thrust x, the device will go into production and just scaled up as solar powered thrust on a satellite needing no propellant is so much better than just plain old thrust requiring propellant? Solar power for satellites will likely get cheaper and more powerful each year into the future.
Yes It would be very expensive to make. Our DIYers here, that work on their frustrums run as well campaings to raise funds for their projects. I believe it is at least 10000 dollars for each of them so far. And their are working "only" on the models that do not have superconducting features.
In this regard if some new folks are willing to add some dollar to the cause I am sure SeeShells, Rfmwguy (where is he by the way?) and Monomorphic would be glad for donations.
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#152 by Elmar Moelzer on 31 Aug, 2016 13:49
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REBCO HTSC cable is about 200 USD per meter, if I am not mistaken. Not sure how much you guys would need.
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#153 by Monomorphic on 31 Aug, 2016 14:54
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The concave-convex optical cavity setup yields the strongest E-fields.
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#154 by JonB on 31 Aug, 2016 16:04
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Found this as I was doing some research to catch up on the discussion:
https://arxiv.org/ftp/arxiv/papers/1103/1103.0390.pdf
Interesting read, hope it hasn't been posted and discussed already, I'm only to thread 4 in review.... LOT of reading.
Is there a way to extrapolate 2D data into a 3D application?
*modified for spelling error -
#155 by Prunesquallor on 31 Aug, 2016 17:16
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The paris are open to guess which items are covered in the new test report/paper of Eagleworks
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1 - Emdrive effect shown to exist in vacuum condition.
2 - Emdrive thrust measured for a superconductive cavity.
3 - Emdrive effect shown to exist for a configuration which includes the power supply of the microwave generator.
4 - Emdrive thrust investigated for various RF input power and various electro-magnetic modes configurations.
5 - Emdrive thrust shown to exist in free fall condition (no acceleration).
6 - Statement that no Emdrive effect could be detected in a clean vacuum environment.
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#156 by Oakey on 31 Aug, 2016 17:26
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Anyone else see latest experimental results suggest strong magnetic fields impart mass on electrons?
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#157 by SeeShells on 31 Aug, 2016 17:45
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The concave-convex optical cavity setup yields the strongest E-fields.
NICE WORK Monomorfic!
Would you please do one more with a flat Small End and a curved Big End? Please please please.
Best,
Shell -
#158 by Star One on 31 Aug, 2016 19:16
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Anyone else see latest experimental results suggest strong magnetic fields impart mass on electrons?
I assume you mean this.
http://phys.org/news/2016-08-electrons-mass-presence-high-magnetic.html -
#159 by Monomorphic on 31 Aug, 2016 19:43
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The concave-convex optical cavity setup yields the strongest E-fields.
NICE WORK Monomorfic!
Would you please do one more with a flat Small End and a curved Big End? Please please please.
Best,
Shell
Surprisingly, a little better with small end flat.
