-
#1320 by TheTraveller on 03 Jan, 2017 11:26
-
No solution converges at the small cap for any mode in the pointy cone, as shown in Rodal's diagram below.
EDIT: the orange line has been added by TheTraveller to show the theoretical cutoff, but has been placed by instinct and not by calculus.
Maybe we could talk of some "gradient cut-off zone" instead of a sharp cut-off occurring in an open waveguide, but:
1) the same kind of phenomenon occurs in both situations at the same limit,
2) a few millimeters is not a distance we can qualify of "thick" especially with the remaining room before reaching the end cap.
It is fairly easy for anyone to vary the small end plate diameter, while keeping the same big end plate diameter and cone angle and observing what happens to the small end plate eddy currents as the small end plate diameter gets smaller and smaller. -
#1321 by meberbs on 03 Jan, 2017 14:28
-
What is also seen in your drawing is at Cut-Off there are no end plate reflections occurring, just a whole lot of reflections off the side walls, that chew up energy and heat up the area of the wide wall where the reflection are occurring.
I had to add 2 reflections, not "a whole lot"
As others have already calculated there should be no dramatic decrease in Q from the lack of end plate reflections (in fact it looks like it increases based on X_ray's results). The point of my correction to your diagram was to show why this makes intuitive sense (mostly for others here since I didn't expect you to get this)
We are all in agreement that there is a section where little to no EM energy resides (and hence it is wasted mass to extend this section too long). We also all agree that the highest energy concentration, and hence also highest losses occur just before that point for the investigated modes. It seems that you still don't accept that putting the end plate just before that section seems to increase the loss, not decrease it. -
#1322 by xyzzy on 03 Jan, 2017 17:07
-
We are all in agreement that there is a section where little to no EM energy resides (and hence it is wasted mass to extend this section too long). We also all agree that the highest energy concentration, and hence also highest losses occur just before that point for the investigated modes. It seems that you still don't accept that putting the end plate just before that section seems to increase the loss, not decrease it.
From the losses point of view, there should be an optimal position of the small endplate, approximately where the peak surface current density on the plate equals the peak current density on the sidewall. The reason is that ohmic losses go with I-squared (rather than with I), and minimum I-squared should be reached when the current density is spread evenly rather than concentrated only on the endplate or only on the sidewalls.
There should exist (theoretically) an even lower loss geometry if the corners are rounded so as to make the whole transition area from sidewall to small endplate have a constant surface current density.
P.S. This lowest loss configuration does not necessarily have to be also the maximum thrust configuration. If thrust turns out to be a surface interaction effect, it might skew the optimum somewhat towards the higher endplate current density (presumably somewhat more like NSF1701A rather than like TT_new03 above). -
#1323 by Craig_VG on 03 Jan, 2017 17:51
-
Centauri Dreams has posted a part two to the previous post on analyzing the EM Drive papers. This is written by George HathawayQuote
Forward:
The concluding part of the Tau Zero Foundation’s examination of what is being called the ‘EmDrive’ appears today. It’s a close analysis of the recent paper by Harold ‘Sonny’ White and Paul March in the Journal of Propulsion and Power. Electrical engineer George Hathaway runs Hathaway Consulting Services, which has worked with inventors and investors since 1979 via an experimental physics laboratory near Toronto, Canada. Hathaway’s concentration is on novel propulsion and energy technologies. He has authored dozens of technical papers as well as a book, is a patent-holder and has hosted and lectured at various international symposia.
Introduction:
White et al are to be congratulated for attempting to measure the small thrusts allegedly produced by a novel thruster whose operating mechanism is not only not understood but purportedly violates fundamental physical laws. They have made considerable effort to reduce the possibility of measurement artifact. However it appears that there are some fundamental problems with the interpretation of the measurement data produced by their thrust balance. This document will analyse the measurement procedure and comment on the interpretation.
http://www.centauri-dreams.org/?p=36890 -
#1324 by Monomorphic on 03 Jan, 2017 18:01
-
What would others think about constructing a cardboard frustum, and covering it with copper EMI shielding conductive adhesive tape? Stuff like this: http://a.co/ceU6h4U
After running a few sims using a dialectric layer over top of the copper tape (0.025mm), with the dialectric properties set to that of cardboard (relative permitivity ~3.2) at 1mm thick, I think may be possible to confirm resonance using the 8W amp with an infrared camera. Resonance is ~20Mhz lower with the 1mm cardboard lining, with comparable E-field strengths. I have not checked Q as that is a lengthy process.
I considered covering the interior of the cardboard frustum with copper as then I wouldn't need to simulate the dialectric, but I think the IR cameras may have difficulty seeing through (or the heat conducting through) the 1mm of cardboard at 8W RF power. Once resonance is confirmed with IR, then it would be easy enough to cover the interior with copper - and even replace the end-plates with thicker copper plate.
Seems like this could be a cheap way to confirm resonance before spending the money on more expensive machined frustums.
-
#1325 by Peter Lauwer on 03 Jan, 2017 18:12
-
But does anyone have an idea why I see TWO peaks, at 2905 and 2909 MHz in the resonance spectrum (S11 measurement) as described in https://forum.nasaspaceflight.com/index.php?topic=41732.msg1625271#msg1625271 ?
-
#1326 by Monomorphic on 03 Jan, 2017 19:53
-
But does anyone have an idea why I see TWO peaks, at 2905 and 2909 MHz in the resonance spectrum (S11 measurement) as described in https://forum.nasaspaceflight.com/index.php?topic=41732.msg1625271#msg1625271 ?
With a simple loop positioned as you indicated, I see only one peak, at 2.90266Ghz. It looks like TE112, but I need to check the H-fields to make sure.
I built out your full antenna and am running another sweep. Will let you know if I see the second peak.
-
#1327 by rfmwguy on 03 Jan, 2017 20:14
-
But does anyone have an idea why I see TWO peaks, at 2905 and 2909 MHz in the resonance spectrum (S11 measurement) as described in https://forum.nasaspaceflight.com/index.php?topic=41732.msg1625271#msg1625271 ?
Yes, I do. The dual resonance is based on your antenna location. I witnessed this on more than one occasion. You will need to adjust x y and z axis injection to merge the dual resonance mode. -
#1328 by WarpTech on 03 Jan, 2017 20:40
-
What would others think about constructing a cardboard frustum, and covering it with copper EMI shielding conductive adhesive tape? Stuff like this: http://a.co/ceU6h4U
After running a few sims using a dialectric layer over top of the copper tape (0.025mm), with the dialectric properties set to that of cardboard (relative permitivity ~3.2) at 1mm thick, I think may be possible to confirm resonance using the 8W amp with an infrared camera. Resonance is ~20Mhz lower with the 1mm cardboard lining, with comparable E-field strengths. I have not checked Q as that is a lengthy process.
I considered covering the interior of the cardboard frustum with copper as then I wouldn't need to simulate the dialectric, but I think the IR cameras may have difficulty seeing through (or the heat conducting through) the 1mm of cardboard at 8W RF power. Once resonance is confirmed with IR, then it would be easy enough to cover the interior with copper - and even replace the end-plates with thicker copper plate.
Seems like this could be a cheap way to confirm resonance before spending the money on more expensive machined frustums.
Not a bad idea. But I would use NOMEX paper. It is what is used in power transformers. It comes in rolls from .5 mill up. It has temperature withstand > 200C, so it's not going to burn or degrade from the heat. It's also more rigid than plain cardboard and makes nice smooth curves!
http://www.professionalplastics.com/NOMEXPAPER
The only issue would be air pressure making it expand and flex, so keep it well ventilated and it should work I think. -
#1329 by Monomorphic on 03 Jan, 2017 21:49
-
But does anyone have an idea why I see TWO peaks, at 2905 and 2909 MHz in the resonance spectrum (S11 measurement) as described in https://forum.nasaspaceflight.com/index.php?topic=41732.msg1625271#msg1625271 ?
In addition to the TE112, there appears to be a TM11x mode very nearby. I agree with rfmwguy, this is likely because of your antenna shape and position.
-
#1330 by rq3 on 03 Jan, 2017 21:57
-
Based on earlier threads and discussions, I have done a few VERY primitive experiments in vacuum exploring the Crookes radiometer effect. It is possible to maintain a force on a vane at 10 milliTorr under infrared excitation. The effect is immediately visible to the naked eye. It is not rotation (aka, a Crookes radiometer). It is a unidirectional force, in other words, it provides thrust without the loss of mass. In essence, it is an infrared driven Emdrive.
https://en.wikipedia.org/wiki/Thermal_transpiration
See also references to Knudsen pump.
See also https://en.wikipedia.org/wiki/Dufour_effect
I had originally conceived this to be an unnecessarily complex fabrication, but after mulling it over I reduced it to the essentials which were available as household materials (with the exception of the vacuum system, which I already own).
I suspect that WarpTech's conjecture that the Emdrive is basically a microwave driven heat pump is correct. This is not to say that the effect is not useful, because it certainly may be. But don't look for flying cars anytime soon. WarpTech, if I have taken you out of context, my apologies.
More to follow. I'm trying to find the foamed molybdenum sheet I have stashed somewhere to push this further.
The effect I think I'm seeing may have nothing to do whatsoever with Shawyer's claims so should NOT be construed as an explanation for his claimed effect, nor should it be construed in any manner as a reason to not pursue the Shawyer claims. I can see only very slight hints of achieving the thrust levels extrapolated by Shawyer based on my observations.
I may be (and probably am) full of it, but seeing an expected effect, based on known science, with a clear route to enhancing the effect, gives me hope. I'll report either way. As SeaShells says, "All data is good data". -
#1331 by FattyLumpkin on 03 Jan, 2017 22:37
-
Revaluation of Mbelek and Lachièze-Rey scalar tensor theory of gravitation to explain the measured forces in asymmetric resonant cavities https://arxiv.org/abs/1701.00454
-
#1332 by WarpTech on 03 Jan, 2017 23:02
-
Based on earlier threads and discussions, I have done a few VERY primitive experiments in vacuum exploring the Crookes radiometer effect. It is possible to maintain a force on a vane at 10 milliTorr under infrared excitation. The effect is immediately visible to the naked eye. It is not rotation (aka, a Crookes radiometer). It is a unidirectional force, in other words, it provides thrust without the loss of mass. In essence, it is an infrared driven Emdrive.
https://en.wikipedia.org/wiki/Thermal_transpiration
See also references to Knudsen pump.
See also https://en.wikipedia.org/wiki/Dufour_effect
I had originally conceived this to be an unnecessarily complex fabrication, but after mulling it over I reduced it to the essentials which were available as household materials (with the exception of the vacuum system, which I already own).
I suspect that WarpTech's conjecture that the Emdrive is basically a microwave driven heat pump is correct. This is not to say that the effect is not useful, because it certainly may be. But don't look for flying cars anytime soon. WarpTech, if I have taken you out of context, my apologies.
More to follow. I'm trying to find the foamed molybdenum sheet I have stashed somewhere to push this further.
The effect I think I'm seeing may have nothing to do whatsoever with Shawyer's claims so should NOT be construed as an explanation for his claimed effect, nor should it be construed in any manner as a reason to not pursue the Shawyer claims. I can see only very slight hints of achieving the thrust levels extrapolated by Shawyer based on my observations.
I may be (and probably am) full of it, but seeing an expected effect, based on known science, with a clear route to enhancing the effect, gives me hope. I'll report either way. As SeaShells says, "All data is good data".
I'm glad you're doing some tests. The effect that describes Crookes Radiometer is a force that is proportional to the "perimeter" of the vanes. The air moves along the cooler side until it reaches the edge, and then accelerates toward the warm side, causing a pressure imbalance that drives the rotation.
In that regard, I've ordered some 50 um mesh screen, metal and nylon to make the vanes out of. Not only will this allow it to operate at nearly ambient pressures because the mean free path for air molecules is ~100 nm, it should boost the force many thousands of times due to the greatly increased perimeter of the individual mesh holes. I expect it to spin around my test rig rather fast! We shall see.
See attached.
-
#1333 by rq3 on 03 Jan, 2017 23:13
-
Based on earlier threads and discussions, I have done a few VERY primitive experiments in vacuum exploring the Crookes radiometer effect. It is possible to maintain a force on a vane at 10 milliTorr under infrared excitation. The effect is immediately visible to the naked eye. It is not rotation (aka, a Crookes radiometer). It is a unidirectional force, in other words, it provides thrust without the loss of mass. In essence, it is an infrared driven Emdrive.
https://en.wikipedia.org/wiki/Thermal_transpiration
See also references to Knudsen pump.
See also https://en.wikipedia.org/wiki/Dufour_effect
I had originally conceived this to be an unnecessarily complex fabrication, but after mulling it over I reduced it to the essentials which were available as household materials (with the exception of the vacuum system, which I already own).
I suspect that WarpTech's conjecture that the Emdrive is basically a microwave driven heat pump is correct. This is not to say that the effect is not useful, because it certainly may be. But don't look for flying cars anytime soon. WarpTech, if I have taken you out of context, my apologies.
More to follow. I'm trying to find the foamed molybdenum sheet I have stashed somewhere to push this further.
The effect I think I'm seeing may have nothing to do whatsoever with Shawyer's claims so should NOT be construed as an explanation for his claimed effect, nor should it be construed in any manner as a reason to not pursue the Shawyer claims. I can see only very slight hints of achieving the thrust levels extrapolated by Shawyer based on my observations.
I may be (and probably am) full of it, but seeing an expected effect, based on known science, with a clear route to enhancing the effect, gives me hope. I'll report either way. As SeaShells says, "All data is good data".
I'm glad you're doing some tests. The effect that describes Crookes Radiometer is a force that is proportional to the "perimeter" of the vanes. The air moves along the cooler side until it reaches the edge, and then accelerates toward the warm side, causing a pressure imbalance that drives the rotation.
In that regard, I've ordered some 50 um mesh screen, metal and nylon to make the vanes out of. Not only will this allow it to operate at nearly ambient pressures because the mean free path for air molecules is ~100 nm, it should boost the force many thousands of times due to the greatly increased perimeter of the individual mesh holes. I expect it to spin around my test rig rather fast! We shall see.
See attached.
We're definitely oin the same page. The foamed molybdenum I mentioned is comparable to what you are after. I used it years ago as a gas filter in a high temp application. How can I send you a piece if and when I find it? -
#1334 by Stormbringer on 04 Jan, 2017 00:13
-
Molybdenum?
What's up with that? Did someone grab a bunch of scrabble blocks shake it up in a can and throw it out on the table and that was what the name was to be from a bunch of random alphabetical tiles? Or was it some puffed up self satisfied smug jerk wagering that no one will ever be able to pronounce or spell it without looking it up? -
#1335 by Rodal on 04 Jan, 2017 00:56
-
Molybdenum?
It is used for many alloys. It is also used for a very useful application: molybdenum disulfide (MoS2) as a solid lubricant and a high-pressure high-temperature (HPHT) antiwear agent.
What's up with that? Did someone grab a bunch of scrabble blocks shake it up in a can and throw it out on the table and that was what the name was to be from a bunch of random alphabetical tiles? Or was it some puffed up self satisfied smug jerk wagering that no one will ever be able to pronounce or spell it without looking it up?
In the trade it usually referred to as "Moly"
-
#1336 by dustinthewind on 04 Jan, 2017 01:37
-
No solution converges at the small cap for any mode in the pointy cone, as shown in Rodal's diagram below.
EDIT: the orange line has been added by TheTraveller (and not by Rodal) to show the theoretical cutoff, but has been placed by instinct and not by calculus, so I changed my post to reflect this.
What Rodal showed is there is some thicker "gradient cut-off zone" beyond Shawyer's theoretical "cut-off limit" instead of a sharp cut-off occurring in an open waveguide.
But The Traveller is also right the waves will quickly decay after the limit and won't reach the pointy end cap.
So Shawyer's 0.82 rule has to say something. It is not due to a real cut-off as we thought first, after which the waves would not exist anymore, but to another phenomenon which occurs at about the same threshold, that is not completely understood. Maybe TheTraveller is on the right path.
The reason the higher modes, TE013 in particular, penetrate deeper into the cone tip is because it is a higher frequency. The (shorter the wavelength/higher frequency) the smaller the hole the radiation can pass through. Visible light is a very short wavelength so we don't notice the effect much but with microwaves it becomes very noticeable as with a normal microwave oven and the small holes so we can see in. We see it in Rodal's/TT's image where at the higher frequency it decays further into the tip. If it can penetrate the barrier before it fully decays (the tip of the cone was cut off) the portion that penetrates beyond cone tip that was cut off begins to osculate again at a fraction of the energy and can be said to have tunneled through.
Some good literature on the matter here: http://www.feynmanlectures.caltech.edu/II_24.html 24–3The cutoff frequency .
I find it fascinating that the wave pattern can appear to disappear in mid space, as if it is reflecting off a barrier, or some anti wave was annihilating it in mid step. I'm tempted to grasp at the idea of waves that travel backwards in time to cause quanta of energy to be absorbed. Speculation that light could be electron-poistron pairs and positrons being negative mass electrons running backwards in time. https://en.wikipedia.org/wiki/Wheeler%E2%80%93Feynman_absorber_theory
Not really sure where to go with all that though.
However, as Feynman points out in the later part of his lecture, the radiation path becomes more steep in angle in the wave-guide as it proceeds. Seemingly, slowing the group velocity and increasing the phase velocity. There may be other ways of looking at it. He also hints at standing wave solutions.QuoteNaturally, it should be possible for waves to go in either direction. Since both types of waves can be present at the same time, there will be the possibility of standing-wave solutions.
-
#1337 by dustinthewind on 04 Jan, 2017 02:36
-
But does anyone have an idea why I see TWO peaks, at 2905 and 2909 MHz in the resonance spectrum (S11 measurement) as described in https://forum.nasaspaceflight.com/index.php?topic=41732.msg1625271#msg1625271 ?
With a simple loop positioned as you indicated, I see only one peak, at 2.90266Ghz. It looks like TE112, but I need to check the H-fields to make sure.
I built out your full antenna and am running another sweep. Will let you know if I see the second peak.
I was wondering at your antenna simulation. Is it just me or does your antenna look to be 90 degrees of in rotation from his antenna? Here is one of his old images and the link to the posting of the image: https://forum.nasaspaceflight.com/index.php?topic=40959.msg1608034#msg1608034
and your image, antenna lower right hand side. -
#1338 by dustinthewind on 04 Jan, 2017 02:57
-
Based on earlier threads and discussions, I have done a few VERY primitive experiments in vacuum exploring the Crookes radiometer effect. It is possible to maintain a force on a vane at 10 milliTorr under infrared excitation. The effect is immediately visible to the naked eye. It is not rotation (aka, a Crookes radiometer). It is a unidirectional force, in other words, it provides thrust without the loss of mass. In essence, it is an infrared driven Emdrive.
https://en.wikipedia.org/wiki/Thermal_transpiration
See also references to Knudsen pump.
See also https://en.wikipedia.org/wiki/Dufour_effect
I had originally conceived this to be an unnecessarily complex fabrication, but after mulling it over I reduced it to the essentials which were available as household materials (with the exception of the vacuum system, which I already own).
I suspect that WarpTech's conjecture that the Emdrive is basically a microwave driven heat pump is correct. This is not to say that the effect is not useful, because it certainly may be. But don't look for flying cars anytime soon. WarpTech, if I have taken you out of context, my apologies.
More to follow. I'm trying to find the foamed molybdenum sheet I have stashed somewhere to push this further.
The effect I think I'm seeing may have nothing to do whatsoever with Shawyer's claims so should NOT be construed as an explanation for his claimed effect, nor should it be construed in any manner as a reason to not pursue the Shawyer claims. I can see only very slight hints of achieving the thrust levels extrapolated by Shawyer based on my observations.
I may be (and probably am) full of it, but seeing an expected effect, based on known science, with a clear route to enhancing the effect, gives me hope. I'll report either way. As SeaShells says, "All data is good data".
You may not be observing a true vacuum effect. The pressure you mention 10mTorr I think is very close to the maximum thrust pressure for a Crookes Radiometer.
See this video at time 4:23, he mentions a maximum in thrust at about 7mTorr:
Sent you a personal message oyzw that might help. Suggestions others had when I googled, "watching youtube in china". -
#1339 by oyzw on 04 Jan, 2017 03:38
-
Hello, can you help me download this video? I can't open this page in china. Thanks very muchBased on earlier threads and discussions, I have done a few VERY primitive experiments in vacuum exploring the Crookes radiometer effect. It is possible to maintain a force on a vane at 10 milliTorr under infrared excitation. The effect is immediately visible to the naked eye. It is not rotation (aka, a Crookes radiometer). It is a unidirectional force, in other words, it provides thrust without the loss of mass. In essence, it is an infrared driven Emdrive.
https://en.wikipedia.org/wiki/Thermal_transpiration
See also references to Knudsen pump.
See also https://en.wikipedia.org/wiki/Dufour_effect
I had originally conceived this to be an unnecessarily complex fabrication, but after mulling it over I reduced it to the essentials which were available as household materials (with the exception of the vacuum system, which I already own).
I suspect that WarpTech's conjecture that the Emdrive is basically a microwave driven heat pump is correct. This is not to say that the effect is not useful, because it certainly may be. But don't look for flying cars anytime soon. WarpTech, if I have taken you out of context, my apologies.
More to follow. I'm trying to find the foamed molybdenum sheet I have stashed somewhere to push this further.
The effect I think I'm seeing may have nothing to do whatsoever with Shawyer's claims so should NOT be construed as an explanation for his claimed effect, nor should it be construed in any manner as a reason to not pursue the Shawyer claims. I can see only very slight hints of achieving the thrust levels extrapolated by Shawyer based on my observations.
I may be (and probably am) full of it, but seeing an expected effect, based on known science, with a clear route to enhancing the effect, gives me hope. I'll report either way. As SeaShells says, "All data is good data".
You may not be observing a true vacuum effect. The pressure you mention 10mTorr I think is very close to the maximum thrust pressure for a Crookes Radiometer.
See this video at time 4:23, he mentions a maximum in thrust at about 7mTorr:
