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#2440 by X_RaY on 06 Nov, 2016 21:21
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This is true when you scale the frustum with frequency. If you keep the dimensions constant and allow a higher mode to be present,the Q also increases with frequency.Not even sure why EWL used TM212 instead of TE012 or TE013, not to mention RCs of X2, 3 or 4 larger in size would have "Q"s orders of magnitude higher. Perhaps it's safe to assert that force/Watt should/would also increase..to what extent I do not know, but Sonny did address extrapolations in his Ames talk (as I recall). Additionally, a larger cavity "supposedly" would "handle" more power input. This is why I aforementioned was ready to go with a bigger build: say x2 or 2.5 times larger. Anyone interested? I'd ask Shell Jamie or Dave to handle the RF and testing, while I'd be responsible for fabrication. FL
Let's consider the first report. There they stated, there are problems to excite TE012 using the existing/ already builded frustum. Therefore TM212 was used. It's quite logic to get straight forward with the existing one because:
1. There is a lot of experience with the existing frustum and they can compare the new results with the older.
2. Calculate, build and explore another frustum with TE012 optimized geometry would cost a lot of time and money.
3. The actual test may used to check(confirm or reject) if it works at all, not to optimize it to high thrust levels, that may done during future work.
4. A much larger frustum doesn't make it more easy to test the device.
What I have seen in simulations with the NASA frustum and others is that the loop antenna mounted on the side wall is not the ideal location to excite TE01x. It can be done, but requires a number of conditions to be just right - and even then can be fleeting. It is far easier to excite TE01x using either a loop antenna or circularizing antenna positioned along the central axis (as seen in Shawyer's recent patent).
As for frustum size, I will probably migrate towards c-band as fabricating cavities that size is much more economical. There is a small hit in Q for going smaller, but that can be made up for elsewhere.
There is a double hit in the stored energy. The energy stored in the cavity will be proportional to;
E ~ P*Q/f
And the reaction counter mass that the frustum is pushing against is ~ E/c2. Therefore, you want to maximize energy storage. Higher frequency will have lower Q and much lower energy storage for the same power input.
I have tested this for the "p" value only but I am pretty sure it's true for the other intrgers of TXmnp also.
http://forum.nasaspaceflight.com/index.php?topic=39214.msg1536095#msg1536095 -
#2441 by WarpTech on 06 Nov, 2016 21:45
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This is true when you scale the frustum with frequency. If you keep the dimensions constant and allow a higher mode to be present,the Q also increases with frequency.Not even sure why EWL used TM212 instead of TE012 or TE013, not to mention RCs of X2, 3 or 4 larger in size would have "Q"s orders of magnitude higher. Perhaps it's safe to assert that force/Watt should/would also increase..to what extent I do not know, but Sonny did address extrapolations in his Ames talk (as I recall). Additionally, a larger cavity "supposedly" would "handle" more power input. This is why I aforementioned was ready to go with a bigger build: say x2 or 2.5 times larger. Anyone interested? I'd ask Shell Jamie or Dave to handle the RF and testing, while I'd be responsible for fabrication. FL
Let's consider the first report. There they stated, there are problems to excite TE012 using the existing/ already builded frustum. Therefore TM212 was used. It's quite logic to get straight forward with the existing one because:
1. There is a lot of experience with the existing frustum and they can compare the new results with the older.
2. Calculate, build and explore another frustum with TE012 optimized geometry would cost a lot of time and money.
3. The actual test may used to check(confirm or reject) if it works at all, not to optimize it to high thrust levels, that may done during future work.
4. A much larger frustum doesn't make it more easy to test the device.
What I have seen in simulations with the NASA frustum and others is that the loop antenna mounted on the side wall is not the ideal location to excite TE01x. It can be done, but requires a number of conditions to be just right - and even then can be fleeting. It is far easier to excite TE01x using either a loop antenna or circularizing antenna positioned along the central axis (as seen in Shawyer's recent patent).
As for frustum size, I will probably migrate towards c-band as fabricating cavities that size is much more economical. There is a small hit in Q for going smaller, but that can be made up for elsewhere.
There is a double hit in the stored energy. The energy stored in the cavity will be proportional to;
E ~ P*Q/f
And the reaction counter mass that the frustum is pushing against is ~ E/c2. Therefore, you want to maximize energy storage. Higher frequency will have lower Q and much lower energy storage for the same power input.
I have tested this for the "p" value only but I am pretty sure it's true for the other intrgers of TXmnp also.
http://forum.nasaspaceflight.com/index.php?topic=39214.msg1536095#msg1536095
Looking at the data in your post. Q/f is getting smaller as Q is getting bigger. The frequency gets bigger, faster. Even though the Q is lower for a lower frequency, there is more energy stored for the "same" power input.
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#2442 by flux_capacitor on 06 Nov, 2016 22:30
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You guys are connecting the dots about the choice of Shawyer selecting TE013 over lower or higher modes… as well as over any TM mode. Some sort of compromise to achieve greatest stored energy and Q near one end.
What would be the approximative size of a L-band ~900 MHz TE013 frustum? Governmental regulators decided to set frequencies for industrial magnetrons and now solid-state microwave generators: 433, 896, 915, 922, 929, 2450, 5800 MHz. Any frequency can be achieved with a lab RF power amp (in the tens to hundreds of watts) but microwave generators built for the industry work with higher power in the kilowatt range (and maybe at an attractive cost, I don't know). -
#2443 by mikegem on 06 Nov, 2016 23:16
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You guys are connecting the dots about the choice of Shawyer selecting TE013 over lower or higher modes… as well as over any TM mode. Some sort of compromise to achieve greatest stored energy and Q near one end.
What would be the approximative size of a L-band ~900 MHz TE013 frustum? Governmental regulators decided to set frequencies for industrial magnetrons and now solid-state microwave generators: 433, 896, 915, 922, 929, 2450, 5800 MHz. Any frequency can be achieved with a lab RF power amp (in the tens to hundreds of watts) but microwave generators built for the industry work with higher power in the kilowatt range (and maybe at an attractive cost, I don't know).
The frequencies you note are a subset of the ISM (Industrial, Scientific, Medical) frequencies within which certain regulated parameters like unintentional leakage radiation are relaxed compared to other frequencies. The ISM bands are mostly harmonically related so that one can use low quality sources that may have significant second/third harmonic output.
It's usually the case that $/Watt within the ISM bands is lower than at other frequencies. Some of this is due to economies of scale (think of how many microwave ovens there are at 2450 MHz) and some because of the less stringent design requirements for ISM sources.
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#2444 by M.LeBel on 07 Nov, 2016 00:32
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This illustration appears to answer my previous question about whether or not something is known to (or could) come out of the frustum under certain conditions. This would not be considered a closed system, right?
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#2445 by WarpTech on 07 Nov, 2016 01:03
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This illustration appears to answer my previous question about whether or not something is known to (or could) come out of the frustum under certain conditions. This would not be considered a closed system, right?
No, this is just a bad graphic representation. The vectors should end at the end plates. -
#2446 by M.LeBel on 07 Nov, 2016 02:00
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This illustration appears to answer my previous question about whether or not something is known to (or could) come out of the frustum under certain conditions. This would not be considered a closed system, right?
No, this is just a bad graphic representation. The vectors should end at the end plates.
Hummm!!! Should tell that to Paul March! Taken from: Frustum modes overview 2 with Q-Factors_Rev-A.pdf
Why? Are you telling me that the frustum is a perfect shielding no matter the power injected into the cavity?
Has this been tested or is this a general assumption? It seems to me that the effects are detected outside the cavity (pendulum etc.) and yet everyone is only looking inside the cavity .. -
#2447 by ThinkerX on 07 Nov, 2016 02:17
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Quote
Why? Are you telling me that the frustum is a perfect shielding no matter the power injected into the cavity?
Has this been tested or is this a general assumption? It seems to me that the effects are detected outside the cavity (pendulum etc.) and yet everyone is only looking inside the cavity ..
You just stated one of the biggest single issues with the EM Drive.
The list of forces that can escape the cavity is real short. -
#2448 by FattyLumpkin on 07 Nov, 2016 02:34
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I believe with the many sims performed by X_Ray and Monomorphic that reliably stimulating TE012 or TE013 has been demonstrated by "correct" placement of the antenna(ae). Not to mention that NASA said they would be using PLL for the campaign...AIAA peer review study.
It is understood that NASA went with what mode that "worked best" from their previous study. I would have hoped they could have at least moved forward with TE012 since that would work in the geometry of their frustum. Moving forward with a x2 large geometry would put us in the Megahertz range 1.8804/2=0.9402, so what would this do to the Q of 22,000? Quadruple or?
Attachments NASA Frustum TE012 in simulation, original dimensions and then reduced/scaled down by 2.794 for a cubesat placement (images by X_Ray)
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#2449 by SeeShells on 07 Nov, 2016 02:36
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If microwave energy was escaping the microwave cavity in any amount please stand back further from your microwave oven.This illustration appears to answer my previous question about whether or not something is known to (or could) come out of the frustum under certain conditions. This would not be considered a closed system, right?
No, this is just a bad graphic representation. The vectors should end at the end plates.
Hummm!!! Should tell that to Paul March! Taken from: Frustum modes overview 2 with Q-Factors_Rev-A.pdf
Why? Are you telling me that the frustum is a perfect shielding no matter the power injected into the cavity?
Has this been tested or is this a general assumption? It seems to me that the effects are detected outside the cavity (pendulum etc.) and yet everyone is only looking inside the cavity ..
It may be better to look at what can enter the cavity that the cavity energy can act upon then what maybe escaping, other than a little thermal activity.
Shell
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#2450 by WarpTech on 07 Nov, 2016 03:05
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This illustration appears to answer my previous question about whether or not something is known to (or could) come out of the frustum under certain conditions. This would not be considered a closed system, right?
No, this is just a bad graphic representation. The vectors should end at the end plates.
Hummm!!! Should tell that to Paul March! Taken from: Frustum modes overview 2 with Q-Factors_Rev-A.pdf
Why? Are you telling me that the frustum is a perfect shielding no matter the power injected into the cavity?
Has this been tested or is this a general assumption? It seems to me that the effects are detected outside the cavity (pendulum etc.) and yet everyone is only looking inside the cavity ..
If you input enough power to melt the copper, sure it can get out. This is Faraday's law of induction. My conjecture is that magnetic flux can escape when there is a voltage drop in the copper, where current is flowing. Regardless however, even a perfectly collimated photon rocket of the same power would not produce nearly as much thrust as has been measured by experiments. So that's probably not it.
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#2451 by M.LeBel on 07 Nov, 2016 03:09
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If microwave energy was escaping the microwave cavity in any amount please stand back further from your microwave oven.This illustration appears to answer my previous question about whether or not something is known to (or could) come out of the frustum under certain conditions. This would not be considered a closed system, right?
No, this is just a bad graphic representation. The vectors should end at the end plates.
Hummm!!! Should tell that to Paul March! Taken from: Frustum modes overview 2 with Q-Factors_Rev-A.pdf
Why? Are you telling me that the frustum is a perfect shielding no matter the power injected into the cavity?
Has this been tested or is this a general assumption? It seems to me that the effects are detected outside the cavity (pendulum etc.) and yet everyone is only looking inside the cavity ..
It may be better to look at what can enter the cavity that the cavity energy can act upon then what maybe escaping, other than a little thermal activity.
Shell
Why? Are you telling me that the frustum is a perfect shielding no matter the power injected into the cavity?
Has this been tested or is this a general assumption? It seems to me that the effects are detected outside the cavity (pendulum etc.) and yet everyone is only looking inside the cavity ..
[/quote]
If microwave energy was escaping the microwave cavity in any amount please stand back further from your microwave oven.
It may be better to look at what can enter the cavity that the cavity energy can act upon then what maybe escaping, other than a little thermal activity.
Shell
[/quote]
Shell, I didn't say microwaves were escaping
But something could.. The way I see it is that the cavity could work a bit like a rectifier allowing only one half of the wave to show up beyond the frustum as evanescent wave. If the front end of the wave is sticking out, it is a lower time rate i.e. gravity; the cavity moves toward it without never reaching it. This is like imparting half of an inertial wave to the cavity. A better constructed cavity would have the half back end of the wave sticking out at the back of the cavity and a front end wave sticking out at the front of the cavity. This full wave inertial and causal structure would impart a complete push-pull action to the cavity. These sticking out half waves would also influence locally detectors like pendulum etc.
So, the question is ... is something coming out of the frustum? I suggested liquid crystal and polarizer to detect/visualize any stable electrical differential on the outer surface of the frustum...
I have read enough around here to know that the whole adventure is highly empirical and in bad need of some theory or explanation. And, an equation is a really bad substitute for thinking things out..
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#2452 by M.LeBel on 07 Nov, 2016 03:35
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This illustration appears to answer my previous question about whether or not something is known to (or could) come out of the frustum under certain conditions. This would not be considered a closed system, right?
No, this is just a bad graphic representation. The vectors should end at the end plates.
Hummm!!! Should tell that to Paul March! Taken from: Frustum modes overview 2 with Q-Factors_Rev-A.pdf
Why? Are you telling me that the frustum is a perfect shielding no matter the power injected into the cavity?
Has this been tested or is this a general assumption? It seems to me that the effects are detected outside the cavity (pendulum etc.) and yet everyone is only looking inside the cavity ..
If you input enough power to melt the copper, sure it can get out. This is Faraday's law of induction. My conjecture is that magnetic flux can escape when there is a voltage drop in the copper, where current is flowing. Regardless however, even a perfectly collimated photon rocket of the same power would not produce nearly as much thrust as has been measured by experiments. So that's probably not it.
Way before the copper melts, its resistivity will increase creating voltage drop across the thickness of the frustum and charges on the outside surface .... which will radiate, what
?
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#2453 by dustinthewind on 07 Nov, 2016 04:29
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...
I noticed your antenna placement was not exactly on the electric field maximum. If you raise the antenna loop towards the top a bit, and increase its diameter to be in the electric field maximum, I suspect it would enhance the coupling of the antenna to the cavity. Edit: I maybe wrong on the diameter as that may depend on the wavelength of the current in the antenna.
On a side note, I found this thesis for those interested in whispering gallery modes. It deals with, "cavities with an axial asymmetry", toroids, gallery modes, Mode-Matching Analysis, and large Q values. I was curious about it because of it mentioning coupling energy into a toroid cavity. Not sure it would be all that useful but figured it mentioned a lot of subjects frequently discussed. Mode-Matching Analysis of Whispering-Gallery-Mode Cavities
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#2454 by giulioprisco on 07 Nov, 2016 06:44
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Next Big Future picked up one of the papers posted here...
There is nothing new in the Next Big Future article.
I am sorry but NBF has the paper (first link in their article).
I saw the Next Big Future article first and downloaded the paper just in case it disappears, then I came here to see what you guys say. Is the leaked paper the same paper that will be published in AIAA’s Journal of Propulsion and Power in December? Or a draft version?
How close is the paper to the final version that will be published? Note that I'll write about this today, so thos in the know might prefer not to answer. At the same time, now that the paper is out, it will be all over the press in the next few days, there's no way to put it back in the box. -
#2455 by oliverio on 07 Nov, 2016 07:42
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Next Big Future picked up one of the papers posted here...
There is nothing new in the Next Big Future article.
I am sorry but NBF has the paper (first link in their article).
I saw the Next Big Future article first and downloaded the paper just in case it disappears, then I came here to see what you guys say. Is the leaked paper the same paper that will be published in AIAA’s Journal of Propulsion and Power in December? Or a draft version?
How close is the paper to the final version that will be published? Note that I'll write about this today, so thos in the know might prefer not to answer. At the same time, now that the paper is out, it will be all over the press in the next few days, there's no way to put it back in the box.
The consensus is no. It is very likely not the same paper that will appear in the AIAA journal.
At the very least, this is an "early draft;" this much was said by TheTraveller when he leaked the paper to NSF and Reddit. This means it could be anything from a trashed version to a near-copy, but the truth is likely somewhere between.
Additionally as several posts here have mentioned, much of the "leaked content" is not new, dating back to 2014-2015, and leading users to suspect that we do not have the current sum of research by Eagleworks.
I encourage everyone to give Nasa and Eagleworks the professional benefit of the doubt: let them do their jobs, we already have a scheduled release. There is no academic that wants their drafts thrown around as current work (sounds like a bad dream). -
#2456 by giulioprisco on 07 Nov, 2016 07:50
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Next Big Future picked up one of the papers posted here...
There is nothing new in the Next Big Future article.
I am sorry but NBF has the paper (first link in their article).
I saw the Next Big Future article first and downloaded the paper just in case it disappears, then I came here to see what you guys say. Is the leaked paper the same paper that will be published in AIAA’s Journal of Propulsion and Power in December? Or a draft version?
How close is the paper to the final version that will be published? Note that I'll write about this today, so thos in the know might prefer not to answer. At the same time, now that the paper is out, it will be all over the press in the next few days, there's no way to put it back in the box.
The consensus is no. It is very likely not the same paper that will appear in the AIAA journal.
At the very least, this is an "early draft;" this much was said by TheTraveller when he leaked the paper to NSF and Reddit. This means it could be anything from a trashed version to a near-copy, but the truth is likely somewhere between.
Additionally as several posts here have mentioned, much of the "leaked content" is not new, dating back to 2014-2015, and leading users to suspect that we do not have the current sum of research by Eagleworks.
I encourage everyone to give Nasa and Eagleworks the professional benefit of the doubt: let them do their jobs, we already have a scheduled release. There is no academic that wants their drafts thrown around as current work (sounds like a bad dream).
Thanks Oliverio. Can I quote you? -
#2457 by Nerm999 on 07 Nov, 2016 08:36
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Are we allowed to discuss what was found in the paper or is going to be removed until the release in December?
No alas, we can't discuss in details the fact Eagleworks managed to dramatically reduce and quantize any spurious mundane cause of thrust, yet still measured a consistent force in a hard vacuum two orders of magnitude higher than a perfectly collimated photon rocket.
Same thing for their ultra-low friction Cavendish rotary experiment that has been video recorded, showing rotation with all cables and power supply onboard in ambient air. A setup that, if cleverly designed, would be immune to any thermal expansion of the frustum or of the wires that could be (are) present in former experiments. For that part, we have to wait until next year (at least) since it is planned for their next test campaign.
And what about that frustum without a dielectric inside showing a measurable force, along a direction that reverses when a dielectric is present at the small end and the frequency tuned accordingly to achieve resonance in both cases! Too bad that we can't discuss this behavior.
@flux_capacitor Obviously we can't discuss the stuff in the leaked paper that's still linked to in the Next Big Future article, but is there a source for the stuff we can't discuss in your second and third paragraphs?? -
#2458 by Star One on 07 Nov, 2016 08:52
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Next Big Future picked up one of the papers posted here...
There is nothing new in the Next Big Future article.
I am sorry but NBF has the paper (first link in their article).
I saw the Next Big Future article first and downloaded the paper just in case it disappears, then I came here to see what you guys say. Is the leaked paper the same paper that will be published in AIAA’s Journal of Propulsion and Power in December? Or a draft version?
How close is the paper to the final version that will be published? Note that I'll write about this today, so thos in the know might prefer not to answer. At the same time, now that the paper is out, it will be all over the press in the next few days, there's no way to put it back in the box.
The consensus is no. It is very likely not the same paper that will appear in the AIAA journal.
At the very least, this is an "early draft;" this much was said by TheTraveller when he leaked the paper to NSF and Reddit. This means it could be anything from a trashed version to a near-copy, but the truth is likely somewhere between.
Additionally as several posts here have mentioned, much of the "leaked content" is not new, dating back to 2014-2015, and leading users to suspect that we do not have the current sum of research by Eagleworks.
I encourage everyone to give Nasa and Eagleworks the professional benefit of the doubt: let them do their jobs, we already have a scheduled release. There is no academic that wants their drafts thrown around as current work (sounds like a bad dream).
I was wondering this and hasn't this leak damaged the examination of the EM drive by mudding the waters and allowing further perhaps unwarranted criticism of the EW to be made? -
#2459 by qraal on 07 Nov, 2016 09:38
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Let's not waste Sonny's money by reading the rough draft. He's paid for Open Access, so let's await the real thing.
But something could.. The way I see it is that the cavity could work a bit like a rectifier allowing only one half of the wave to show up beyond the frustum as evanescent wave. If the front end of the wave is sticking out, it is a lower time rate i.e. gravity; the cavity moves toward it without never reaching it. This is like imparting half of an inertial wave to the cavity. A better constructed cavity would have the half back end of the wave sticking out at the back of the cavity and a front end wave sticking out at the front of the cavity. This full wave inertial and causal structure would impart a complete push-pull action to the cavity. These sticking out half waves would also influence locally detectors like pendulum etc.
?