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#1660 by oliverio on 13 Jan, 2016 02:58
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Photons move at the velocity C from any given reference frame.
It seems analytically true that "Q" in a photon-excited quality is a relativistic property to me. For a given proof, consider the following.
Draw or imagine a laser and mirror reflector that is very long with a relatively smaller observer somewhere in the middle. Photons can be observed oscillating between these two mirrors, but the field constitutes a standing wave etc.
Now consider moving at relativistic speeds in either direction parallel to the laser beam. It will take longer for photons to move from the reflected mirror you are moving away from, and you will observe those photons traveling toward the approaching mirror as arriving faster in virtue of your movement.
Of course, if both mirrors were moving parallel to you at the same speed, the effect would not be observable to you; it would, however, be observable to anyone observing your local reference frame (or more specifically the reference frame of the EMdrive).
If the predictions from GR are true about photon density and asymmetric pressure and etc. are true, this would make sense, because the drive would essentially constitute a "warp bubble" in which the reference frame of the inside of the drive is seeing more spacetime flow past than the outside is.
note that the same thing is true of any gravitating object, so if an emdrive in operation gains "effective mass," then there is no real problem with this idea. Any object with mass, effective or not, will see more local spacetime than an object outside of its gravitationally warped field. It really just means it'd have to get heavier from any observing reference frame as it accelerates, which is consistent with other predictions from SR as far as I understand. This would also clearly solve COE issues. -
#1661 by RFPlumber on 13 Jan, 2016 03:04
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<rant on>
Armed with my first-hand experience about how easy it is to produce 500 uN of asymmetric “thrust” by just having a vertical metal plate dissipating 100W of heat, I decided to take another look at all the “positive” results listed for EmDrive… IMHO, we are going through some kind of mass delusion and wishful thinking effect here… There seems to be really only 1-2 cases for which there is not enough information available to dismiss or question them right away; the rest all fall short of not just providing extraordinary evidence (required for "extraordinary claims", right?) but of even applying some critical thinking and Occam’s razor to the “evidence” at hand to eliminate reasonable doubt… My own “reasonable doubt” at this point is pretty basic – any force which continues many seconds after the RF pulse is most likely either thermal or is caused by some structural material deformation (or both); and any force which is small and perfectly aligned with an RF pulse, production of which requires magnets and high DC voltages or currents (aka magnetron) is most likely Lorentz. In both of these cases I expect to see a convincing argument to overcome my reasonable doubt. Yet there is none. Moreover, the approach taken is that any asymmetry in forces produced must be due to some new effects… Amazing… Here’s just a few examples:
Shawyer’s notes for NASA, 2002 – individual force curves show a long exponential decay post-RF. Some are even changing their original direction during the decay. Why are these not 100% thermal, again?
Tajmar – in their ambient air tests they take a unidirectional(!) force with a familiar thermal profile (following temperature rise, remaining long after the RF pulse), and call any changes to this force “thrust”. Really? In their vacuum tests they see a force of like 18..27 uN (which does not quite change according to the amount of RF power but never mind), and immediately attribute it to “thrust”. This is with a magnetron and 800W(!) of DC power nearby. To put this in perspective, EW had 9 uN of clear null force in their setup just because of how wires go.
EW – their tests look OK. Still, their frustum test and their dummy load test are both showing a reversed force after the RF pulse. No discussion why an RF pulse through a dummy load (sometimes?) results in a long-lasting after-force in the opposite direction.
Cannae LLC superconducting – looks OK, but again no discussion about what they did to prove it was not Lorentz.
<rant off>
Working on modifying the frustum length to move the frequency higher, above the small end cut-off. Also improving RF power indicator to have a visual for reflected power during test runs. There seems to be an expectation that “there must be a force during the RF pulse”, and a lack of it is somehow attributed to no RF power in the cavity…. Well, my understanding is that according to existing physics it is quite the opposite – there should be zero force… Which is exactly what seems to be happening.
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#1662 by oliverio on 13 Jan, 2016 03:17
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<rant on>
Armed with my first-hand experience about how easy it is to produce 500 uN of asymmetric “thrust” by just having a vertical metal plate dissipating 100W of heat, I decided to take another look at all the “positive” results listed for EmDrive… IMHO, we are going through some kind of mass delusion and wishful thinking effect here… There seems to be really only 1-2 cases for which there is not enough information available to dismiss or question them right away; the rest all fall short of not just providing extraordinary evidence (required for "extraordinary claims", right?) but of even applying some critical thinking and Occam’s razor to the “evidence” at hand to eliminate reasonable doubt… My own “reasonable doubt” at this point is pretty basic – any force which continues many seconds after the RF pulse is most likely either thermal or is caused by some structural material deformation (or both); and any force which is small and perfectly aligned with an RF pulse, production of which requires magnets and high DC voltages or currents (aka magnetron) is most likely Lorentz. In both of these cases I expect to see a convincing argument to overcome my reasonable doubt. Yet there is none. Moreover, the approach taken is that any asymmetry in forces produced must be due to some new effects… Amazing… Here’s just a few examples:
Shawyer’s notes for NASA, 2002 – individual force curves show a long exponential decay post-RF. Some are even changing their original direction during the decay. Why are these not 100% thermal, again?
Tajmar – in their ambient air tests they take a unidirectional(!) force with a familiar thermal profile (following temperature rise, remaining long after the RF pulse), and call any changes to this force “thrust”. Really? In their vacuum tests they see a force of like 18..27 uN (which does not quite change according to the amount of RF power but never mind), and immediately attribute it to “thrust”. This is with a magnetron and 800W(!) of DC power nearby. To put this in perspective, EW had 9 uN of clear null force in their setup just because of how wires go.
EW – their tests look OK. Still, their frustum test and their dummy load test are both showing a reversed force after the RF pulse. No discussion why an RF pulse through a dummy load (sometimes?) results in a long-lasting after-force in the opposite direction.
Cannae LLC superconducting – looks OK, but again no discussion about what they did to prove it was not Lorentz.
<rant off>
Working on modifying the frustum length to move the frequency higher, above the small end cut-off. Also improving RF power indicator to have a visual for reflected power during test runs. There seems to be an expectation that “there must be a force during the RF pulse”, and a lack of it is somehow attributed to no RF power in the cavity…. Well, my understanding is that according to existing physics it is quite the opposite – there should be zero force… Which is exactly what seems to be happening.
WIth these theoretical discussions, if you give some of the various theories charity, it is understandable that there might be a reversed force at some point, although I am not suggesting that's what you saw with your test set-up.
It's just that mode resonance is awful chaotic, and if asymmetric radiation patterns of the generated mode create thrust, then mode degeneration might easily unload power as thrust in another direction as the interference boundaries shift all about.
Once again, not proposing this happened with your set-up, but it's not hard to imagine under the constraints of the above theory or others a fashion in which a resonator drive isn't going to sometimes want to rachet backwards.
(Ever seen something vibrate around a low friction surface? It's random-walk-city.) -
#1663 by RFPlumber on 13 Jan, 2016 03:33
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<rant on>
Armed with my first-hand experience about how easy it is to produce 500 uN of asymmetric “thrust” by just having a vertical metal plate dissipating 100W of heat, I decided to take another look at all the “positive” results listed for EmDrive… IMHO, we are going through some kind of mass delusion and wishful thinking effect here…
WIth these theoretical discussions, if you give some of the various theories charity, it is understandable that there might be a reversed force at some point, although I am not suggesting that's what you saw with your test set-up.
But why even start with all those amazing theories when a simple explanation is readily available (and nobody has done anything to prove the simple explanation wrong or even question it enough)?
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#1664 by Stormbringer on 13 Jan, 2016 03:48
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That was it! He was talking about an english wheel i think.
These guys:
That Orange County Chopper guy (Jesse James) had a shop with antique metal hammers as well as rollers and benders. He said that such machines (manual metal hammer rigs) are now quite rare and the people who know how to use them are getting rare too. But custom bike shops might be a place to look for metal shapers.Thanks Zen...do you have a gut feel as to what the mil thickness should be?
A friend with a lathe spun some 10 GHz and 24 GHz feedhorns designed by Paul Wade, W1GHZ. He had no problem with the .020" Copper disks I gave him for the 10 GHz feedhorns but the .010" material just crumpled. For something as large as a fustrum my guess would be .030" - .040". I have raised metal with hammers (smithing) but have not done any metal spinning. I have heard from a good source it can be dangerous. The only downside of moving metal with hammers is your neighbors get very annoyed.
http://www.onlinemetals.com/merchant.cfm?id=966&step=2&top_cat=87&showunits=mm
Thanks - Dave
Concur on safety. We did a lot of metal spinning on some feedhorn construction a decade or so ago. It works very well but - like any lathe operation - it can be dangerous; there are lots of ways to detach body parts from portions of fingers up to major limbs and the blood is hard to clean off the lathe and the unit under construction LOL . It is also a heck of a lot of fun; I had an excellent instructor (an old machinist who had done metal spinning for a LOT of years) and once you learned how and how to do it safely it was a real hoot.
Smithing (hammers) is also a lot of fun but as you point out your neighbors may express a different opinion.
Herman -W5HLP
http://www.BaltimoreKnife.com and
https://www.youtube.com/aweme (the Man at Arms:Reforged series)
are my brothers
I have plenty of connections in and through them to get pretty much anything fabricated They have 4 power hammers and an english wheel among LOTS of other stuff. -
#1665 by rfmwguy on 13 Jan, 2016 03:55
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You have an excellent opportunity to quantify/measure both lorentz and thermal influences with your experiment. First, you must observe movement, then eliminate the error sources one by one. Without the initial observation, there is nothing to quantify.<rant on>
Armed with my first-hand experience about how easy it is to produce 500 uN of asymmetric “thrust” by just having a vertical metal plate dissipating 100W of heat, I decided to take another look at all the “positive” results listed for EmDrive… IMHO, we are going through some kind of mass delusion and wishful thinking effect here…
WIth these theoretical discussions, if you give some of the various theories charity, it is understandable that there might be a reversed force at some point, although I am not suggesting that's what you saw with your test set-up.
But why even start with all those amazing theories when a simple explanation is readily available (and nobody has done anything to prove the simple explanation wrong or even question it enough)? -
#1666 by RFPlumber on 13 Jan, 2016 04:16
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You have an excellent opportunity to quantify/measure both lorentz and thermal influences with your experiment. First, you must observe movement, then eliminate the error sources one by one. Without the initial observation, there is nothing to quantify.<rant on>
Armed with my first-hand experience about how easy it is to produce 500 uN of asymmetric “thrust” by just having a vertical metal plate dissipating 100W of heat, I decided to take another look at all the “positive” results listed for EmDrive… IMHO, we are going through some kind of mass delusion and wishful thinking effect here…
WIth these theoretical discussions, if you give some of the various theories charity, it is understandable that there might be a reversed force at some point, although I am not suggesting that's what you saw with your test set-up.
But why even start with all those amazing theories when a simple explanation is readily available (and nobody has done anything to prove the simple explanation wrong or even question it enough)?
This describes a brute force approach which will never succeed as it is impossible to eliminate all error sources. One could instead take a different path and show that the force observed does not follow the stimulus for the corresponding error source but rather shows behavior consistent with what is expected. Yet, this is not happening.
Yes, absolutely, one needs to first detect force, for which there is no obvious simple explanation. IMHO, Cannae Superconducting and EW are the only 2 examples at the moment. -
#1667 by dustinthewind on 13 Jan, 2016 07:02
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I was contemplating an experiment where the frustum could be held at center mass, so that when it heats up the expansion of the mass would not induce a force of thrust.
To further the idea, I was thinking of locking a frustum in an insulated/sealed sphere and the sphere would then be locked to the frustum inside and the sphere would also be held center mass so that the sphere could thermally expand. The sealed/insulated sphere being a closed system for a time should eliminate, out-gassing, convection and holding it center mass eliminate thermal expansion. The only problem left I think might be buoyancy, as the sphere will change volume with material expansion but I would think that might be trivial if the temperature/pressure of the material of the sphere is known? I would think a sphere should be a good shape for containing any pressure changes also. If thermal energy does get out, I would think a sphere should also have the least drag on the atmosphere?
Or if doing it in vacuum just suspend the frustum by center mass, but there is still thermal radiation effects so maybe the insulated sphere may still help.
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#1668 by Chrochne on 13 Jan, 2016 09:33
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"Scientist Claims We Could Manipulate Gravity With Current Technology"
http://www.iflscience.com/artificial-gravitational-fields-are-possible-current-technology
Nice article with the link to the paper. Paper have 12 pages.
What I like about it is that it mentiones that study of the "gravity" is in the passive and there are means to turn it to active.
It reminds me the fact, that we are really too much focused on the chemical rockets and there is very little investment done, into the science, that looks for alternatives. One example could be the EW and their ongoing war for funds.... -
#1669 by Rodal on 13 Jan, 2016 12:40
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You have an excellent opportunity to quantify/measure both lorentz and thermal influences with your experiment. First, you must observe movement, then eliminate the error sources one by one. Without the initial observation, there is nothing to quantify.<rant on>
Armed with my first-hand experience about how easy it is to produce 500 uN of asymmetric “thrust” by just having a vertical metal plate dissipating 100W of heat, I decided to take another look at all the “positive” results listed for EmDrive… IMHO, we are going through some kind of mass delusion and wishful thinking effect here…
WIth these theoretical discussions, if you give some of the various theories charity, it is understandable that there might be a reversed force at some point, although I am not suggesting that's what you saw with your test set-up.
But why even start with all those amazing theories when a simple explanation is readily available (and nobody has done anything to prove the simple explanation wrong or even question it enough)?
This describes a brute force approach which will never succeed as it is impossible to eliminate all error sources. One could instead take a different path and show that the force observed does not follow the stimulus for the corresponding error source but rather shows behavior consistent with what is expected. Yet, this is not happening.
Yes, absolutely, one needs to first detect force, for which there is no obvious simple explanation. IMHO, Cannae Superconducting and EW are the only 2 examples at the moment.
Excellent point: to eliminate error sources, one first has to understand the error sources. But the problem here is that the error sources have not been fully investigated and understood by the experimenters. For example, the effect of natural thermal air convection from the fustrum with vortex shedding and Navier Stokes equation in a low Reynolds number regime above Stokes flow cannot be understood by experimenters, there has not been any Computational Fluid Dynamics of it, or visual study of it in slow motion, or experimental profiling of the air convection (no smoke, tufts, evaporating suspensions, oil, fog, sublimation studies of air flow; or strobe lights and film cameras or high-speed digital cameras visualization).
Using statistical methods is problematic because of the low sample population, typically a Gaussian distribution is assumed a priori, but clearly this is a not fully justified assumption (assumption of independence: averages of random variables independently drawn from independent distributions) since the sample population is so small that one cannot even show a well formed histogram, and the sample population is too small to be able to extract robust statistical estimates from it.
Clearly, of all the tests performed up to date, NASA's tests have been the ones where most technical details have been disclosed. And NASA's tests in partial vacuum eliminate the effect of thermal convection through the air.
The inventor, Shawyer, for example, has not even disclosed all the EM Drive dimensions for any of his published tests (see TheTravellerReturns message in https://www.reddit.com/r/EmDrive/comments/40pwj8/shawyer_245_ghz_demonstrator_frustum_exact/). Why would a researcher keep the geometrical dimensions of a published tested sample confidential forcing the reading public to have to rely on estimates? Not knowing the sample dimensions, and much less knowing the geometrical tolerance, an independent observer cannot even verify the natural frequencies or quality of resonance (Q) for the published results. -
#1670 by rfmwguy on 13 Jan, 2016 13:29
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My own opinion (not that it supercedes anything else) is that first, something must be observed. Second, once that is done, evaluate how far out of the noise the observation is. Third, try to eliminate common sources of noise such as data jitter, Lorentz and thermal. Fourth, redesign experiment to produce results higher above any remaining noise.
You have an excellent opportunity to quantify/measure both lorentz and thermal influences with your experiment. First, you must observe movement, then eliminate the error sources one by one. Without the initial observation, there is nothing to quantify.<rant on>
Armed with my first-hand experience about how easy it is to produce 500 uN of asymmetric “thrust” by just having a vertical metal plate dissipating 100W of heat, I decided to take another look at all the “positive” results listed for EmDrive… IMHO, we are going through some kind of mass delusion and wishful thinking effect here…
WIth these theoretical discussions, if you give some of the various theories charity, it is understandable that there might be a reversed force at some point, although I am not suggesting that's what you saw with your test set-up.
But why even start with all those amazing theories when a simple explanation is readily available (and nobody has done anything to prove the simple explanation wrong or even question it enough)?
This describes a brute force approach which will never succeed as it is impossible to eliminate all error sources. One could instead take a different path and show that the force observed does not follow the stimulus for the corresponding error source but rather shows behavior consistent with what is expected. Yet, this is not happening.
Yes, absolutely, one needs to first detect force, for which there is no obvious simple explanation. IMHO, Cannae Superconducting and EW are the only 2 examples at the moment.
I'll summarize what I did...take it or leave it:
1) Mesh frustum walls was used to naturally vent thermals. It was at a sacrifice to Q. Turns out thermal lift was mainly focused on magnetron assembly on top of frustum. A thermal plume developed...pretty stable and linear.
2) After 4 test runs and spreadsheet analysis on displacement, a statistically significant displacement against lift occurred during magnetron on. It measured approximately 177 micronewtons, or 18 milligrams of force. This observation was enough to consider the test non-null yet indeterminate as to the cause. System noise, or measurement floor was at or below about 50 micronewtons.
3) A redesign is underway with a goal to increase the displacement 100 times, or 17.5 millinewtons. This will be the second observational phase. This will be done with the same mechanical test setup but an improved solid frustum and a controlled magnetron output.
The beauty of what you are doing, is there are no blueprints or lab supervisors looking over your shoulder. You can choose your own methodology and design. You can choose brute force or delicate precision. It does not matter. Neither one is right or wrong, for this is not a classroom, it is your own time and money.
And the bottom line is, the only person you have to please is yourself. No one reading this has at much at stake as you do. No one is doing what you are doing. Just do your best and satisfy yourself. If what I did helps, fine. If what shell is doing, fine. If not...do your own thing.
<edit> corrected goal as 17.5 millinewtons or 100x improvement -
#1671 by Rodal on 13 Jan, 2016 13:49
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.... It measured approximately 177 micronewtons, or 18 grams of force. This observation was enough to consider the test non-null yet indeterminate as to the cause. System noise, or measurement floor was at or below about 50 micronewtons.
3) A redesign is underway with a goal to increase the displacement 10 times, or 17.5 micronewtons...
1) What is the plan that may enable you to achieve the << increase the displacement 10 times>> (*). How are you planning to be able to increase the force or the displacement so much?
Are you planning to use the same input power?
Are you planning that the force increase will come from a quality factor of resonance (Q) >10 times larger on your new test than on your prior test?
_________
(*) Just a typo question. Is there a typo on the force units? Please review your units, as 17.5 microNewtons is 1/10th of 177 microNewtons (0.1 of the force instead of 10 times the force) instead of << increase the displacement 10 times>>. Did you mean increase the force from 177 microNewtons to 1.77 milliNewtons? -
#1672 by rfmwguy on 13 Jan, 2016 14:12
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thanks. 17.5 millinewtons is the goal, a 100x improvement. It will be same steup except for much higher Q and much better return loss. I will use a cleaner magnetron signal, with an inverter like shell is using..... It measured approximately 177 micronewtons, or 18 grams of force. This observation was enough to consider the test non-null yet indeterminate as to the cause. System noise, or measurement floor was at or below about 50 micronewtons.
3) A redesign is underway with a goal to increase the displacement 10 times, or 17.5 micronewtons...
1) Just a typo question. Is there a typo on the force units? Please review your units, as 17.5 microNewtons is 1/10th of 177 microNewtons (0.1 of the force instead of 10 times the force) instead of << increase the displacement 10 times>>. Did you mean increase the force from 177 microNewtons to 1.77 milliNewtons?
2) A more important question: What is the plan that may enable you to achieve the << increase the displacement 10 times>>. How are you planning to be able to increase the force or the displacement so much?
Are you planning to use the same input power?
Are you planning that the force increase will come from a quality factor of resonance (Q) >10 times larger than on your prior test?
Mr Li. liked the steps I took to minimize Lorentz and made one suggestion of power leads near magnetron.
To summarize, much higher Q, better return loss and cleaner signal will be the 3 primary changes this spring.
I chose the goal somewhat randomly assuming a 20dB improvement in return loss, at least 10X more RF getting to the frustum at resonance.
- distracted by work edits
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#1673 by Rodal on 13 Jan, 2016 14:13
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If the results of your new test, where you hope to have a displacement 100 times greater, turns out instead to give similar displacement as the one measured in your prior test, would you agree to consider the test results of your new test to be NULL, as your hypothesis of 100 times greater displacement would have been nullified by your new testing ?
thanks. 17.5 millinewtons is the goal, a 100x improvement. It will be same steup except for much higher Q and much better return loss. I will use a cleaner magnetron signal, with an inverter like shell is using..... It measured approximately 177 micronewtons, or 18 grams of force. This observation was enough to consider the test non-null yet indeterminate as to the cause. System noise, or measurement floor was at or below about 50 micronewtons.
3) A redesign is underway with a goal to increase the displacement 10 times, or 17.5 micronewtons...
1) Just a typo question. Is there a typo on the force units? Please review your units, as 17.5 microNewtons is 1/10th of 177 microNewtons (0.1 of the force instead of 10 times the force) instead of << increase the displacement 10 times>>. Did you mean increase the force from 177 microNewtons to 1.77 milliNewtons?
2) A more important question: What is the plan that may enable you to achieve the << increase the displacement 10 times>>. How are you planning to be able to increase the force or the displacement so much?
Are you planning to use the same input power?
Are you planning that the force increase will come from a quality factor of resonance (Q) >10 times larger than on your prior test?
Mr Li. liked the steps I took to minimize Lorentz and made one suggestion of power leads near magnetron.
To summarize, much higher Q, better return loss and cleaner signal will be the 2 primary changes this spring.
I chose the goal somewhat randomly assuming a 20dB improvement in return loss, at least 10X more RF getting to the frustum at resonance. -
#1674 by rfmwguy on 13 Jan, 2016 14:18
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I'd consider the tests non-null, but attributable to a fixed error source that was not amplified by my changes.
If the results of your new test, where you hope to have a displacement 100 times greater, turns out instead to give similar displacement as the one measured in your prior test, would you agree to consider the test results of your new test to be NULL, as your hypothesis of 100 times greater displacement would have been nullified by your new testing ?
thanks. 17.5 millinewtons is the goal, a 100x improvement. It will be same steup except for much higher Q and much better return loss. I will use a cleaner magnetron signal, with an inverter like shell is using..... It measured approximately 177 micronewtons, or 18 grams of force. This observation was enough to consider the test non-null yet indeterminate as to the cause. System noise, or measurement floor was at or below about 50 micronewtons.
3) A redesign is underway with a goal to increase the displacement 10 times, or 17.5 micronewtons...
1) Just a typo question. Is there a typo on the force units? Please review your units, as 17.5 microNewtons is 1/10th of 177 microNewtons (0.1 of the force instead of 10 times the force) instead of << increase the displacement 10 times>>. Did you mean increase the force from 177 microNewtons to 1.77 milliNewtons?
2) A more important question: What is the plan that may enable you to achieve the << increase the displacement 10 times>>. How are you planning to be able to increase the force or the displacement so much?
Are you planning to use the same input power?
Are you planning that the force increase will come from a quality factor of resonance (Q) >10 times larger than on your prior test?
Mr Li. liked the steps I took to minimize Lorentz and made one suggestion of power leads near magnetron.
To summarize, much higher Q, better return loss and cleaner signal will be the 2 primary changes this spring.
I chose the goal somewhat randomly assuming a 20dB improvement in return loss, at least 10X more RF getting to the frustum at resonance.
IOW, if I saw around 177 micronewtons with all the improvements made and validated, I'd consider my design/test stand too noisy to be useful in solving the emdrive question. I would then humbly leave it to others with far better resources than me. -
#1675 by zen-in on 13 Jan, 2016 16:37
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...
2) After 4 test runs and spreadsheet analysis on displacement, a statistically significant displacement against lift occurred during magnetron on. It measured approximately 177 micronewtons, or 18 grams of force.
<edit> corrected goal as 17.5 millinewtons or 100x improvement
177 microNewtons = .018 grams-force -
#1676 by rfmwguy on 13 Jan, 2016 17:06
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boy, I need to stop posting today...yes 18 mg
...
2) After 4 test runs and spreadsheet analysis on displacement, a statistically significant displacement against lift occurred during magnetron on. It measured approximately 177 micronewtons, or 18 grams of force.
<edit> corrected goal as 17.5 millinewtons or 100x improvement
177 microNewtons = .018 grams-force
-
#1677 by Rodal on 13 Jan, 2016 19:53
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In the following post https://forum.nasaspaceflight.com/index.php?topic=39214.msg1474347#msg1474347, I prove, mathematically, that the quality of resonance (Q) scales like the square root of any geometrical dimension, for constant resistivity and magnetic permeability of the interior wall of the cavity and for constant geometrical ratios, constant medium properties μr,εr, and for the same mode shape m,n,p.
In other words, for increasing dimensions of the cavity, preserving all geometrical ratios, and keeping material properties constant and for the same mode shape, the quality of resonance (Q) will increase with the square root of the dimension, also the skin depth will increase with the square root of the dimension, while the frequency will decrease, as the inverse of the dimension.
Furthermore, I previously proved that all three theories for the EM Drive (McCulloch, Shawyer and Notsosureofit) have expressions for the force/inputPower to be proportional to the quality of factor Q times a dimensionless factor g, and we previously proved that the dimensionless factor g (for all three theories: McCulloch, Shawyer and Notsosureofit) remains perfectly constant for constant geometrical ratios, constant medium properties μr,εr, and for the same mode shape m,n,p.
Therefore one concludes that the force per input Power (for all three theories: McCulloch, Shawyer and Notsosureofit) scales like the square root of any geometrical dimension, for constant resistivity and magnetic permeability of the interior wall of the cavity and for constant geometrical ratios, constant medium properties μr,εr, and for the same mode shape m,n,p.
In other words, to maximize the force per input power, according to all three theories: (McCulloch, Shawyer and Notsosureofit) the most efficient EM Drive would be as large as possible, this being due to the fact that the quality of factor of resonance Q (all else being equal) scales like the square root of the geometrical dimensions.
Small cavity EM Drive's (all else being equal) are predicted to have smaller quality of resonance Q and therefore smaller force/inputPower.
It is not clear whether this has been known to EM Drive experimenters, given the fact that the recent experiments by Prof. Tajmar at TU Dresden, Germany, (under advice from Roger Shawyer according to the report) were performed with a much smaller EM Drive, and the fact that there are several EM Drive researchers discussing really tiny EM Drives (as the group in Aachen, Germany) for use in CubeSats. Such EM Drives are predicted to be much more inefficient, having substantially lower force/inputPower.
Of course this was evident, as the efficiency of the EM Drive according to all three theories is predicated on the quality of factor of resonance Q, and it has been known for a long time that Q is a function of material properties as well as size, since the losses are due to surface losses. Hence the volume increases with the cube of the dimensions while the surface losses only increase like the square of the dimensions. Hence the larger the cavity the larger the Q, all else being equal. (A larger animal will have less heat losses than a smaller one, since the ratio of surface area to volume is smaller for a larger animal).
Something that was known to researchers in WWII and that Nobel Prize winner Alvarez exploited for his 40 feet long resonant cavities.(*)
I was reminded of this recently when upon a discussion with Shell I remembered what MIT Prof. Arthur von Hippel had written (before I was born
) regarding Q of resonant cavities being able to approach 1 million for WWII cavities not using superconductivity. (Although von Hippel does not go into this, that motivated me to prove this mathematically, for fun ).
Here is Nobel Prize winner Luis Alvarez (famous for Berkeley's accelerator, MIT Radiation Laboratory -developers of the US Radar in WWII- and the Manhattan project -the Atomic bomb-), standing taller than President Johnson during an award presented to him for his great contributions:
and towering over President Truman:
Luis Alvarez, a tall man with commanding mien, was known for being sometimes outspokenly critical of those opposing his views. For example, when he ridiculed skeptics of his theory about the extinction of dinosaurs due to a meteor. Eventually he was proven correct, even regarding that meteorite
http://newscenter.lbl.gov/2010/03/09/alvarez-theory-on-dinosaur/
He was aboard the Enola Gay during the mission to atomic bomb Hiroshima, and he flew aboard another aircraft to witness the atomic bombing of Nagasaki. After the war he went back to Berkeley and built the first practical hydrogen bubble chamber, a device that would become the standard tool for particle physicists for a generation. A high speed particle would fly through the liquid inside, boiling off the hydrogen as it zipped by. The boiling liquid left a small trail of bubbles behind, photos of which could be used to figure out what had passed through. By 1968, he and his team had helped discover so many new particles with the device, he won a Nobel Prize for his work.
Luis Alvarez, a Reinassance man of the 20th century, who successfully pioneered the design of huge (40 ft) resonant cavities !
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(*) For several interesting stories regarding the 40ft long resonant cavity of Luis Alvarez fabricated with the hydroforming
airplane manufacturing technique at the Douglas Aircraft Company (the historic Berkeley 32 MeV proton linear accelerator which incorporated the "Alvarez drift tube" as the basic acceleration scheme using surplus 200 MHz radar components) see the autobiographical book Panofsky on Physics, Politics, and Peace: Pief Remembers, By Wolfgang K.H. Panofsky and Discovering Alvarez: Selected Works of Luis W. Alvarez with Commentary by His Students and Colleagues
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#1678 by RFPlumber on 13 Jan, 2016 19:58
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I was contemplating an experiment where the frustum could be held at center mass, so that when it heats up the expansion of the mass would not induce a force of thrust.
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Or if doing it in vacuum just suspend the frustum by center mass, but there is still thermal radiation effects so maybe the insulated sphere may still help.
My humble understanding is that suspending the frustum by center mass will not help with anything as its center mass is changing during the test, as frustum heating from RF induced currents is not at all uniform.
Look at all those images of COMSOL surface power dissipation. Here's one I posted for TE012: -
#1679 by dustinthewind on 13 Jan, 2016 20:17
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I was contemplating an experiment where the frustum could be held at center mass, so that when it heats up the expansion of the mass would not induce a force of thrust.
...
Or if doing it in vacuum just suspend the frustum by center mass, but there is still thermal radiation effects so maybe the insulated sphere may still help.
My humble understanding is that suspending the frustum by center mass will not help with anything as its center mass is changing during the test, as frustum heating from RF induced currents is not at all uniform.
Look at all those images of COMSOL surface power dissipation. Here's one I posted for TE012:
If the center of mass remained close to where it was held as an approximation, this should reduce the signal from therm expansion to some extent?
You make an excellent point as to the uneven expansion of the frustum due to the uneven thermal heating.
I have plenty of connections in and through them to get pretty much anything fabricated 
) regarding Q of resonant cavities being able to approach 1 million for WWII cavities not using superconductivity. (Although von Hippel does not go into this, that motivated me to prove this mathematically, for fun