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#1260
by
TheTraveller
on 05 Jan, 2016 01:10
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Technology State of the Art:
Advanced vacuum thrusters:
demonstrated thrust in the 100 micro-Newton range using high fidelity torsion pendula, and in the 1 to 100 milli-Newton range with strain gauge force measurement systems.
Ok the 100uN vac results are as Paul reported earlier.
http://forum.nasaspaceflight.com/index.php?topic=38577.msg1440938#msg1440938
But 1-100mN using strain gauges. Where did that come from?
Good eye Phil, he did confirm 100 micros in vacuum, but with unpublished results as of yet. No idea on the strain guage. The roadmap seemed to be at TRL1 which is where they first started out. I was just glad to see the tech listed on a corporate roadmap...think it was first time I saw this.
Have asked you know who about the strain gauge data. As it is now public knowledge, maybe he will be allowed to give us a reply.
Even at the lower 1mN it is 10x their TP results. At 100mN it is MASSIVE.
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#1261
by
oyzw
on 05 Jan, 2016 01:14
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Technology State of the Art:
Advanced vacuum thrusters:
demonstrated thrust in the 100 micro-Newton range using high fidelity torsion pendula, and in the 1 to 100 milli-Newton range with strain gauge force measurement systems.
Ok the 100uN vac results are as Paul reported earlier.
http://forum.nasaspaceflight.com/index.php?topic=38577.msg1440938#msg1440938
But 1-100mN using strain gauges. Where did that come from?
Good eye Phil, he did confirm 100 micros in vacuum, but with unpublished results as of yet. No idea on the strain guage. The roadmap seemed to be at TRL1 which is where they first started out. I was just glad to see the tech listed on a corporate roadmap...think it was first time I saw this.
Have asked you know who about the strain gauge data. As it is now public knowledge, maybe he will be allowed to give us a reply.
Even at the lower 1mN it is 10x their TP results. At 100mN it is MASSIVE.
Professor Yang has told me very seriously, if EMdrive thrust can not be more than 1 N/KW, the cost of experimental demonstration will be much more than expected, investors will not risk to support research and development. The best way is to manufacture high temperature superconducting cavity directly.
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#1262
by
ThinkerX
on 05 Jan, 2016 01:22
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The Traveler -
A couple pages back you posted a graph from a 2014 test by Shawyer. You also stated this was an actual physical test rather than a simulation.
Just to keep matters straight, does this 2014 Shawyer EM Drive device have a designation you are free to divulge. (I am remembering some of the early confusion with some of Shawyers previous devices here).
Also, if free to do so, is this a superconducting device or something else?
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#1263
by
aero
on 05 Jan, 2016 01:23
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Slightly different thought ...
It has been suggested that an iterative scheme using meep be used to optimize some performance metric. Unfortunately, as far as I know, no one has any idea what such a performance metric should be.
It has also been seriously proposed, and perhaps even applied, that test frustums be driven with a feedback tuning loop to maintain resonance.
To my knowledge no one has proposed using an expert system sensing force in a real laboratory experiment to optimize the RF frequency, switching and power level to maximize force/power while sensing other factors (thermal) that might cause the detected force and attempt to ameliorate such factors.
Who knows how to code such an expert control system?
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#1264
by
rfmwguy
on 05 Jan, 2016 01:32
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Slightly different thought ...
It has been suggested that an iterative scheme using meep be used to optimize some performance metric. Unfortunately, as far as I know, no one has any idea what such a performance metric should be.
It has also been seriously proposed, and perhaps even applied, that test frustums be driven with a feedback tuning loop to maintain resonance.
To my knowledge no one has proposed using an expert system using sensed force to optimize the RF frequency, switching and power level to maximize force/power while sensing other factors (thermal) that might cause the detected force and attempt to ameliorate such factors.
Who knows how to code such an expert control system?
I am with you on this. Mode discussions are fascinating but I don't know where it leads except to perhaps higher effeciencies when the emdrive effect is resolved. I struggled with a decision whether to mechanically or electrically tune for maintaining resonance. In my phase I observational tests, the q was low and tuning was not a factor. A frustum like shells however will have very high q and tuning will be needed. Think she is in manual mode mechanical tuning of the frustum in her first observational tests.
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#1265
by
rfmwguy
on 05 Jan, 2016 01:38
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Technology State of the Art:
Advanced vacuum thrusters:
demonstrated thrust in the 100 micro-Newton range using high fidelity torsion pendula, and in the 1 to 100 milli-Newton range with strain gauge force measurement systems.
Ok the 100uN vac results are as Paul reported earlier.
http://forum.nasaspaceflight.com/index.php?topic=38577.msg1440938#msg1440938
But 1-100mN using strain gauges. Where did that come from?
Good eye Phil, he did confirm 100 micros in vacuum, but with unpublished results as of yet. No idea on the strain guage. The roadmap seemed to be at TRL1 which is where they first started out. I was just glad to see the tech listed on a corporate roadmap...think it was first time I saw this.
Have asked you know who about the strain gauge data. As it is now public knowledge, maybe he will be allowed to give us a reply.
Even at the lower 1mN it is 10x their TP results. At 100mN it is MASSIVE.
Professor Yang has told me very seriously, if EMdrive thrust can not be more than 1 N/KW, the cost of experimental demonstration will be much more than expected, investors will not risk to support research and development. The best way is to manufacture high temperature superconducting cavity directly.
This is good information. If professor yang is retired and is willing, would like to invite her to our humble forum. Perhaps she is not active in research now, but we would be honored by her presence.
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#1266
by
OnlyMe
on 05 Jan, 2016 01:42
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Slightly different thought ...
It has been suggested that an iterative scheme using meep be used to optimize some performance metric. Unfortunately, as far as I know, no one has any idea what such a performance metric should be.
It has also been seriously proposed, and perhaps even applied, that test frustums be driven with a feedback tuning loop to maintain resonance.
To my knowledge no one has proposed using an expert system using sensed force to optimize the RF frequency, switching and power level to maximize force/power while sensing other factors (thermal) that might cause the detected force and attempt to ameliorate such factors.
Who knows how to code such an expert control system?
I am with you on this. Mode discussions are fascinating but I don't know where it leads except to perhaps higher effeciencies when the emdrive effect is resolved. I struggled with a decision whether to mechanically or electrically tune for maintaining resonance. In my phase I observational tests, the q was low and tuning was not a factor. A frustum like shells however will have very high q and tuning will be needed. Think she is in manual mode mechanical tuning of the frustum in her first observational tests.
Maybe the answer will be something like, design a fixed dimension frustum, for the best initial thrust/Kw possible, with a fixed input frequency.., pulsed at a rate that will allow enough time between pulses for the frustum to remain responsive, to the fixed input frequency.
That pulsed input in document TT linked earlier might just.., both address some of the thermal build up issues and allow the drive to operate at a fixed input frequency.
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#1267
by
oyzw
on 05 Jan, 2016 01:43
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Technology State of the Art:
Advanced vacuum thrusters:
demonstrated thrust in the 100 micro-Newton range using high fidelity torsion pendula, and in the 1 to 100 milli-Newton range with strain gauge force measurement systems.
Ok the 100uN vac results are as Paul reported earlier.
http://forum.nasaspaceflight.com/index.php?topic=38577.msg1440938#msg1440938
But 1-100mN using strain gauges. Where did that come from?
Good eye Phil, he did confirm 100 micros in vacuum, but with unpublished results as of yet. No idea on the strain guage. The roadmap seemed to be at TRL1 which is where they first started out. I was just glad to see the tech listed on a corporate roadmap...think it was first time I saw this.
Have asked you know who about the strain gauge data. As it is now public knowledge, maybe he will be allowed to give us a reply.
Even at the lower 1mN it is 10x their TP results. At 100mN it is MASSIVE.
Professor Yang has told me very seriously, if EMdrive thrust can not be more than 1 N/KW, the cost of experimental demonstration will be much more than expected, investors will not risk to support research and development. The best way is to manufacture high temperature superconducting cavity directly.
This is good information. If professor yang is retired and is willing, would like to invite her to our humble forum. Perhaps she is not active in research now, but we would be honored by her presence.
Now She is very like writing poems and travel .
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#1268
by
TheTraveller
on 05 Jan, 2016 02:01
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Slightly different thought ...
It has been suggested that an iterative scheme using meep be used to optimize some performance metric. Unfortunately, as far as I know, no one has any idea what such a performance metric should be.
It has also been seriously proposed, and perhaps even applied, that test frustums be driven with a feedback tuning loop to maintain resonance.
To my knowledge no one has proposed using an expert system sensing force in a real laboratory experiment to optimize the RF frequency, switching and power level to maximize force/power while sensing other factors (thermal) that might cause the detected force and attempt to ameliorate such factors.
Who knows how to code such an expert control system?
My freq locking system does that.
Can vary power from 80mW to 100W and track real time best VSWR. Have added accel sensors to test them for tuning and finding the 1/2 thrust frustum freq bandwidth.
My test system will be a hot bed of various data logged sensors but hey that is what I do.
With respect to Shell, if I have an event like she experienced, it will all be data logged so I can see exactly what happened. Makes the build longer, but hey it is the only way to do this.
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#1269
by
oyzw
on 05 Jan, 2016 03:40
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A partial superconducting cavity (cone bucket is copper, two end plates are YBCO thin films) will be a cheap and convenient . Microwave surface resistivity of YBCO thin films will reach 0.5mΩ-50K.At temperature 50k the microwave surface resistivity of copper will decrease to 0.06 Ω.
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#1270
by
TheTraveller
on 05 Jan, 2016 04:07
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Professor Yang has told me very seriously, if EMdrive thrust can not be more than 1 N/KW, the cost of experimental demonstration will be much more than expected, investors will not risk to support research and development. The best way is to manufacture high temperature superconducting cavity directly.
Sorry don't agree.
1N/kW EmDrive thrusters will totally change sat orbit obtain/sustain and attitude control market.
As example will make CubeSats capable of operation outside LEO and into Lunar / interplanetary space.
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#1271
by
TheTraveller
on 05 Jan, 2016 04:12
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A partial superconducting cavity (cone bucket is copper, two end plates are YBCO thin films) will be a cheap and convenient . Microwave surface resistivity of YBCO thin films will reach 0.5mΩ-50K.At temperature 50k the microwave surface resistivity of copper will decrease to 0.06 Ω.
I should mention, which I did some time ago, that some of my tests will involve cooling the entire copper frustum in liquid N2. Sort of like this:
Copper resistance will drop around 8x, increasing Q approx 3x and thrust 3x. Expect to be able to get Specific Thrust to 4N/kW or better.
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#1272
by
zen-in
on 05 Jan, 2016 04:33
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A partial superconducting cavity (cone bucket is copper, two end plates are YBCO thin films) will be a cheap and convenient . Microwave surface resistivity of YBCO thin films will reach 0.5mΩ-50K.At temperature 50k the microwave surface resistivity of copper will decrease to 0.06 Ω.
I should mention, which I did some time ago, that some of my tests will involve cooling the entire copper frustum in liquid N2. Sort of like this:
u-toob was here
Copper resistance will drop around 8x, increasing Q approx 3x and thrust 3x. Expect to be able to get Specific Thrust to 4N/kW or better.
If you do that be sure you have adequate ventilation in the room or maybe even breath from a scuba tank. It doesn't take very long for LN
2 boil-off to displace the Oxygen in a room. Cooling a fustrum that is being pumped with more than 50 Watts of RF with LN
2 would be an explosive reaction and would definitely give you several Newtons of thrust; besides expelling all the Oxygen in the room.
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#1273
by
zen-in
on 05 Jan, 2016 04:39
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A partial superconducting cavity (cone bucket is copper, two end plates are YBCO thin films) will be a cheap and convenient . Microwave surface resistivity of YBCO thin films will reach 0.5mΩ-50K.At temperature 50k the microwave surface resistivity of copper will decrease to 0.06 Ω.
I have not seen any applications of YBCO thin films at microwave frequencies. Do you have any references that describe this type of application? There was a company that fabricated a Niobium cavity and tested it using liquid Helium. That seems to be the superconductor of choice for RF work.
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#1274
by
dustinthewind
on 05 Jan, 2016 04:51
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Slightly different thought ...
...
To my knowledge no one has proposed using an expert system sensing force in a real laboratory experiment to optimize the RF frequency, switching and power level to maximize force/power while sensing other factors (thermal) that might cause the detected force and attempt to ameliorate such factors.
Who knows how to code such an expert control system?
I suggested using force on the plates to detect resonance earlier. Also a possibility of putting the device in an insulated container to contain thermal effects. If it also isn't allowed to balloon (expand) or exhaust air, as I have seen Shell's suggest, then there also shouldn't be much change in buoyancy either.
It wouldn't allow me to quote the thread as it is closed now so I am just "quoting" it with a link above.
1st quote"...It should be a mode where the current is only traveling around in circles around the axis of the frustum. I can't say a microwave magnetron would be ideal for this or not.
Now why disconnect the end walls from the side walls? It is to detect when resonance happens. When resonance occurs energy is build up and force on the end plates will increase. It is physically observable. I used to observe it with a 60hz solenoid and an aluminum ring hanging down in front or behind the solenoid. The ring will push away because of the changing magnetic field. If the plates are held by position adjustable force sensors you can tell when it hits resonance because the force will increase. Not only that you can control the resonant frequency of the cavity.
Another added benefit is if there was for some reason light was pulling on the big back plate and pushing on the small front plate or side walls, more than it should, it might show up but you would know how the force was behaving on each wall. ..."
and
2nd quote"The suggestion is to just put the thing in an insulated box and weigh the box. Air can move all it wants in the insulated box but it will be a closed system so there should be no net thrust on the box with frustum. An insulate box should keep its temperature constant outside long enough to get meaningful readings with out worrying about convection outside the box if it works. Temperature inside the box could be measured and the volume of the box used to predict buoyancy."
pardon my misuse of buoyancy as jsut because the box heats up doesn't mean it will become buoyant. The box would have to expand if it were sealed air tight to become buoyant.
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#1275
by
TheTraveller
on 05 Jan, 2016 04:51
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A partial superconducting cavity (cone bucket is copper, two end plates are YBCO thin films) will be a cheap and convenient . Microwave surface resistivity of YBCO thin films will reach 0.5mΩ-50K.At temperature 50k the microwave surface resistivity of copper will decrease to 0.06 Ω.
I should mention, which I did some time ago, that some of my tests will involve cooling the entire copper frustum in liquid N2. Sort of like this:
u-toob was here
Copper resistance will drop around 8x, increasing Q approx 3x and thrust 3x. Expect to be able to get Specific Thrust to 4N/kW or better.
If you do that be sure you have adequate ventilation in the room or maybe even breath from a scuba tank. It doesn't take very long for LN2 boil-off to displace the Oxygen in a room. Cooling a fustrum that is being pumped with more than 50 Watts of RF with LN2 would be an explosive reaction and would definitely give you several Newtons of thrust; besides expelling all the Oxygen in the room.
Thanks for the concern and advise.
Have an old range hood and exhaust system that I can install and use to vent the workshop.
My Rf system is totally controlled. Can program to gen from 80mW to 100W. So can cool down the frustum with no power and then let the best VSWR / resonance system find the resonant sweet spot at 80mW power. Then a few short bursts to higher power to measure the generated thrust.
The ability to control and monitor what the frustum Rf system does and sees is considerable as is other monitoring.
Also plan to cool it down with dry ice as a precursor to the LN
2 cooling.
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#1276
by
dustinthewind
on 05 Jan, 2016 04:59
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A partial superconducting cavity (cone bucket is copper, two end plates are YBCO thin films) will be a cheap and convenient . Microwave surface resistivity of YBCO thin films will reach 0.5mΩ-50K.At temperature 50k the microwave surface resistivity of copper will decrease to 0.06 Ω.
I have not seen any applications of YBCO thin films at microwave frequencies. Do you have any references that describe this type of application? There was a company that fabricated a Niobium cavity and tested it using liquid Helium. That seems to be the superconductor of choice for RF work.
I think there are Josephson junctions that generate microwave frequencies with applied DC voltage. I wouldn't think superconductors would have much trouble at that frequency, but then again it would be a thin coating.
http://hyperphysics.phy-astr.gsu.edu/hbase/solids/squid.htmlquote belowFabrication of superconducting YBCO microwave microstrip resonators
"Superconducting resonators and filters in the microwave range are being made by thin film technology and used in base stations for wireless communication.
..."
quote 2 belowMicrowave Superconductivity - Page 180 - Google Books Result
"The Q would be significantly higher by using YBCO coating instead of silver ... "
"...resistance of Bulk YBCO, Metal processed YBCO thick film and YBCO thin films."
Edit: Then again there may be a limit to how large you can get the magnetic field inside before the superconductor will fail and short out, as they have their magnetic field limitations.
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#1277
by
TheTraveller
on 05 Jan, 2016 05:04
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#1278
by
aero
on 05 Jan, 2016 05:32
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One of the big questions, it seems to me, about thermal effects is not so much the magnitude, but the time constant with which these effects act. What would it take to put a number on the time constant of buoyant effects?
Copper, good copper, is expensive so would an aluminium cylinder designed to resonate at 2.45 - 2.47 GHz, operated and tested for thermal effects provide time constant data that could be used in the data analysis of a given copper frustum experiment? If yes, then could a coffee can, or on oatmeal box lined with foil be used to good effect?
Just speculating on a way to determine if the thermal response is quick or slow. Use a cylinder because that should not thrust by all we currently know.
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#1279
by
TheTraveller
on 05 Jan, 2016 05:41
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One of the big questions, it seems to me, about thermal effects is not so much the magnitude, but the time constant with which these effects act. What would it take to put a number on the time constant of buoyant effects?
Copper, good copper, is expensive so would an aluminium cylinder designed to resonate at 2.45 - 2.47 GHz, operated and tested for thermal effects provide time constant data that could be used in the data analysis of a given copper frustum experiment? If yes, then could a coffee can, or on oatmeal box lined with foil be used to good effect?
Just speculating on a way to determine if the thermal response is quick or slow. Use a cylinder because that should not thrust by all we currently know.
That is a good idea Aero.
Yes could make a resonant cylinder cavity that would fill with Rf energy like a frustum and heat thermally similar. If the cavity is sealed, there should be no buoyancy effect from heated air inside the cavity. Q would probably be lower. Will do a few quick calcs.
What thermal effects do you expect to see / monitor?
UPDATE:0.22 m small and big dia
0.25 m length
will generate TE013 resonance at 2.45 GHz