-
#2260 by keithpickering on 11 May, 2016 23:28
-
Hi All,
In Shells set up could magnetic bearings be used to anchor the piano wire top and bottom? If feasible it may show acceleration with a battery test without need to measure deflections?
Sorry just a thought.
The problem isn't really one of bearings, it's one of power transmission in a way that doesn't affect the forces on the apparatus.
If it were me, I would use a solid pendulum (brass rod), suspended by a ball-bearing axle, and copper brushes on the axle rod to transmit the power. The drag on the brushes should be very small with graphite lubricant. And also, use the largest-diameter ball bearings you can get, combined with the smallest diameter brushes, and longest possible pendulum. -
#2261 by SeeShells on 11 May, 2016 23:54
-
Hi Keith,Hi All,
In Shells set up could magnetic bearings be used to anchor the piano wire top and bottom? If feasible it may show acceleration with a battery test without need to measure deflections?
Sorry just a thought.
The problem isn't really one of bearings, it's one of power transmission in a way that doesn't affect the forces on the apparatus.
If it were me, I would use a solid pendulum (brass rod), suspended by a ball-bearing axle, and copper brushes on the axle rod to transmit the power. The drag on the brushes should be very small with graphite lubricant. And also, use the largest-diameter ball bearings you can get, combined with the smallest diameter brushes, and longest possible pendulum.
If I could run microwave through a set of brushes it would be workable.
If I just had the +4000 V from the magnetron supply running down to the magnetron on the frustum I'd still worry about the brushes arcing.
Keep thinking.
Shell -
#2262 by Rodal on 12 May, 2016 00:09
-
4. The calibration plot was created using three different weights on a pulley and averaging the measured deflection of 5 tests each. I should go back and do some statistical analysis on how close each of these were but for now there are other pressing matters.
...
Tomorrow I'm planning to try different wire orientations, if anyone has any suggestions I'm happy to hear them.
[I'll be in class and mostly unavailable until after 8 pm tonight unfortunately]
Yes many things could be at play (if the highest force, responsible for the nonlinearity in the calibration curve is indeed correct)..../...
2) Yes, in the calibration plot, more points are needed between 15 and 35 mN, as the "nonlinearity" seems to be mainly due to the last single point near 32 mN.
The torque vs. angle should be approximately linear up to 20 degrees or so. Maybe the nonlinearity is an experimental artifact???
.../...
Yes for such small displacement pendulum should be close enough to linear. Maybe an artifact from the use of pulley ? If I understand correctly the calibrations weights are "redirected" to horizontal force ? Pulley is not that good for small forces : friction (dry friction ?) at the axis could explain the apparent "softening" for larger forces... also if it is dry friction it should be apparent as hysteresis. Most simple test : approach the equilibrium point by releasing (manually, smoothly) a calibration weight by above equilibrium or by below equilibrium, is there a significant difference in the rest position ?
edit: I mean, when the calibration weight is in place, approach equilibrium (manually, slowly, smoothly) by releasing the pendulum from left or from right deviation. Anyway, check for any difference when last rotation of pulley (before stable equilibrium) was clockwise vs anticlockwise.
Another idea: could the angle of wrap Φ around the pulley decrease with increasing deflection of the pendulum?
Tt = Ts eμ Φ
where:
Tension in tighter side (from calibrating weight to pulley) =Tt
Tension in slacker side (from pulley to pendulum) =Ts
angle (radians) of wrap around pulley= Φ
friction coefficient (between pulley and rope wrapping around pulley) = μ (this is different, it is usually much higher than the coefficient of friction between pulley and its axle !!!! )
Decreasing angle of wrap Φ appears as a smaller Tension measured on the tighter side (from calibrating weight to pulley) for the same Tension in slacker side (from pulley to pendulum).
So, even with constant friction, if the angle of wrap decreases with increasing pendulum rotation, the stiffness will decrease as in a softening spring, due to the decreasing angle of wrap around the pulley. I can't conceive of big differences in the angle of wrap for such small pendulum deflections (mm), so for this idea to be at play, the angle of wrap around the pulley would need to be small to start with. SOLUTION if that is the problem: increase the angle of wrap around the pulley (so that changes in the angles of wrap due to pendulum displacement are less important)
-
#2263 by keithpickering on 12 May, 2016 01:38
-
Hi Keith,Hi All,
In Shells set up could magnetic bearings be used to anchor the piano wire top and bottom? If feasible it may show acceleration with a battery test without need to measure deflections?
Sorry just a thought.
The problem isn't really one of bearings, it's one of power transmission in a way that doesn't affect the forces on the apparatus.
If it were me, I would use a solid pendulum (brass rod), suspended by a ball-bearing axle, and copper brushes on the axle rod to transmit the power. The drag on the brushes should be very small with graphite lubricant. And also, use the largest-diameter ball bearings you can get, combined with the smallest diameter brushes, and longest possible pendulum.
If I could run microwave through a set of brushes it would be workable.
If I just had the +4000 V from the magnetron supply running down to the magnetron on the frustum I'd still worry about the brushes arcing.
Keep thinking.
Shell
Yeah, I was thinking just run 220 V through the brushes, and let the power supply and everything else ride on the pendulum. -
#2264 by rfmwguy on 12 May, 2016 01:48
-
NSF-1701A update -
Torsion pendulum modified at top clamp to improve stickiness. However, return to center still not up to my satisfaction, certainly worse than teeter totter balance. Seems torsion wire is temperature sensitive and perhaps needing to stabilize under weight some more. Have no return spring or anything to inhibit rotation except for oil bath. This dampens oscillations nicely but doesn't induce a return to center. Ideas on centering are welcome. Had thoughts of hanging a pair of vertical balance weights each with redirected force (small string) to horizontal and attach to beam directly opposite each other...reduces sensitivity but might help centering. Also noticed air currents really impact horizontal displacement. Bottom line is system noise must be no more than 50 micronewtons max, which was approximately what I had last time. This is a large setup:
Torsion wire: 24 inch drop of 0.030 inches to top of 14 inch tall central mast.
Coated Hardwood Beam: 107 inches total length, negligible vertical oscillation.
Support wires: from top of central mast to 14 inches in from each end.
Obviously much longer beam than most torsion setups. Can easily redo with smaller beam and less rotational end displacement. Wondering if that in itself would still have stickiness. Probably would but would be masked by far less rotational displacement.
-
#2265 by zellerium on 12 May, 2016 01:51
-
Yes, the x deflection could be described as a rotation about the -z axis (applying rhr) aka clockwise if looking from above the test setup.
The pulley calibration system is far from perfect and I'll work on putting the raw data together either tonight or tomorrow morning. I didn't take average very many tests because the pendulum takes a few minutes to settle back down without any dampening.
Maybe I should incorperate some sort of oil dish dampening system?
The calibration weights are dropped manually onto a small plate that is tied to the magnetron with a piece of thread. So yes, the forces are applied purely horizontally. My system of carefully placing the weights on the pulley should be improved as well, any sudden movements can cause air currents that noticably deflect the pendulum. Also, there was definitely noticable deviation between deflections from the same force application.
Maybe I should devise some sort of rigid calibration system?
I can certainly run the magnetron off-resonance with an S11 of -1 or -2 dB across the spectrum, but I worry about destroying the magnetron. I only have one that fits in the waveguide I'm using so I'd rather not destroy it (it may already be damaged inside for all I know, we've defintely arced to the monopole antenna!)
I can't control exactly where the resonance is, we used to see great resonance almost exactly at 2.45 GHz when didn't have a press fit dielectric. If I still had EM Pro I would probably run simulations to figure out what thickness of dielectric is necessary (or if some amount could be cut off that would be easier). If anyone wants a CAD model of my setup PM me.
-
#2266 by Rodal on 12 May, 2016 02:23
-
Yes, the x deflection could be described as a rotation about the -z axis (applying rhr) aka clockwise if looking from above the test setup.
1) Is this the same cylindrical cavity with constant circular dimensions:
The pulley calibration system is far from perfect and I'll work on putting the raw data together either tonight or tomorrow morning. I didn't take average very many tests because the pendulum takes a few minutes to settle back down without any dampening.
Maybe I should incorperate some sort of oil dish dampening system?
The calibration weights are dropped manually onto a small plate that is tied to the magnetron with a piece of thread. So yes, the forces are applied purely horizontally. My system of carefully placing the weights on the pulley should be improved as well, any sudden movements can cause air currents that noticably deflect the pendulum. Also, there was definitely noticable deviation between deflections from the same force application.
Maybe I should devise some sort of rigid calibration system?
I can certainly run the magnetron off-resonance with an S11 of -1 or -2 dB across the spectrum, but I worry about destroying the magnetron. I only have one that fits in the waveguide I'm using so I'd rather not destroy it (it may already be damaged inside for all I know, we've defintely arced to the monopole antenna!)
I can't control exactly where the resonance is, we used to see great resonance almost exactly at 2.45 GHz when didn't have a press fit dielectric. If I still had EM Pro I would probably run simulations to figure out what thickness of dielectric is necessary (or if some amount could be cut off that would be easier). If anyone wants a CAD model of my setup PM me.
LENGTH=0.180m
DIAMETER =0.1077 m
you run previously at 2.45 GHz, 900 Watts, Q=300 ?
2) Do you still feel like the deflections you are measuring are due to a thermal deformation of the wire leads to the magnetron ? -
#2267 by SeeShells on 12 May, 2016 03:20
-
Tomorrow I'm planning to try different wire orientations, if anyone has any suggestions I'm happy to hear them.
[I'll be in class and mostly unavailable until after 8 pm tonight unfortunately]
Here is a thought. Piano wire and 4 fridge magnets may give you some freedom of movement.
Shell
-
#2268 by zen-in on 12 May, 2016 03:33
-
Hi Keith,Hi All,
In Shells set up could magnetic bearings be used to anchor the piano wire top and bottom? If feasible it may show acceleration with a battery test without need to measure deflections?
Sorry just a thought.
The problem isn't really one of bearings, it's one of power transmission in a way that doesn't affect the forces on the apparatus.
If it were me, I would use a solid pendulum (brass rod), suspended by a ball-bearing axle, and copper brushes on the axle rod to transmit the power. The drag on the brushes should be very small with graphite lubricant. And also, use the largest-diameter ball bearings you can get, combined with the smallest diameter brushes, and longest possible pendulum.
If I could run microwave through a set of brushes it would be workable.
If I just had the +4000 V from the magnetron supply running down to the magnetron on the frustum I'd still worry about the brushes arcing.
Keep thinking.
Shell
One method that might work would be to turn the pendulum into a coax. The pendulum shaft would be non-conductive and would have a collinear tube over it that would be the center conductor. This tube would have a fitting at the top with brushes. Collinear with the inner tube there would be another tube with a dielectric between them. The right angle transition at the beam would just have a hole at the bottom for the pendulum shaft to pass through, where it would fasten to the beam. The top interface would be tricky. Maybe an air bearing would work there. Theoretically possible but the devil is in the details.
Another way of doing the same thing is to use a rotational RF connector at the top and run a solid reinforced Copper tube down to the beam. This doesn't satisfy the torsional force wrt to angular displacement requirement and may have too much friction to be useful. But rotational RF connectors are available.
https://www.timesmicrowave.com/documents/resources/Rotating%20Connect1.pdf -
#2269 by zellerium on 12 May, 2016 04:20
-
1) Is this the same cylindrical cavity with constant circular dimensions:
LENGTH=0.180m
DIAMETER =0.1077 m
you run previously at 2.45 GHz, 900 Watts, Q=300 ?
2) Do you still feel like the deflections you are measuring are due to a thermal deformation of the wire leads to the magnetron ?
Yes, but I would say the length is +- 2 cm of that, which happened when we created a press fit dielectric to remove the need for dielectric screws (which were previously Nylon and melting dramatically).
The deflections definitely look like they are thermal: a quick rise when the magnetron is turned on and a slow decay when it is turned off. I guess I'm assuming the EM Drive 'thrust' we are seeking will present itself as a impulsive force that is either 'on' or 'off' depending on whether a resonant standing wave is present, which seems to be the consensus on what it should look like (right?)
I don't think they are due to air currents because the magnitude of the deflection doesn't increase after multiple consecutive test runs, but I am not sure if the 50 seconds between tests is enough time for the magnetron to cool back to room temperature, it might be.
Shell: Are you suggesting I hang the pendulum with piano wire anchored by magnets that clamp onto the cylinder? Right now I am using steel braided fishing line with wire tensioners to align the mirror and level the cylinder. They are looped through holes in either side of a plate that is bolted to the end plates on either side. The attached picture shows it pretty well, but it needs to be updated with a waveguide, the press fit dielectric, as well as the set screw mount (and a spelling mistake
)
The wires I'm concerned about thermally expanding are the 14 Ga stranded copper wires used to power and ground the magnetron.
So priorities:
Tonight I'll code up something more robust that will allow for speedy data analysis, and outline some formal testing procedures.
Tomorrow morning I'll have time to either do more force calibration, or more test runs. Although I had to temporarily return the VNA to its rightful owner, I locked the cavity on resonance before I left and hopefully it remains as stable as it has recently appeared to be.
What would be more valuable at this point, quantifying the already observed effect or repeating it and attempting to eliminate variables?
-
#2270 by spupeng7 on 12 May, 2016 07:31
-
NSF-1701A update -
Torsion pendulum modified at top clamp to improve stickiness. However, return to center still not up to my satisfaction, certainly worse than teeter totter balance. Seems torsion wire is temperature sensitive and perhaps needing to stabilize under weight some more. Have no return spring or anything to inhibit rotation except for oil bath. This dampens oscillations nicely but doesn't induce a return to center. Ideas on centering are welcome. Had thoughts of hanging a pair of vertical balance weights each with redirected force (small string) to horizontal and attach to beam directly opposite each other...reduces sensitivity but might help centering. Also noticed air currents really impact horizontal displacement. Bottom line is system noise must be no more than 50 micronewtons max, which was approximately what I had last time. This is a large setup:
Torsion wire: 24 inch drop of 0.030 inches to top of 14 inch tall central mast.
Coated Hardwood Beam: 107 inches total length, negligible vertical oscillation.
Support wires: from top of central mast to 14 inches in from each end.
Obviously much longer beam than most torsion setups. Can easily redo with smaller beam and less rotational end displacement. Wondering if that in itself would still have stickiness. Probably would but would be masked by far less rotational displacement.
Rfmw, could you describe or show the clamps or whatever is holding each end of the wire. There may be movement or friction at either end. -
#2271 by RERT on 12 May, 2016 11:05
-
Dr.Rodal -
Forgive me if I make another attempt to explain why I think that the Abraham-Minkowski debate may be relevant within a conductor.
I believe the arguments for differing momenta stem from the difference in the speed of light in a material, irrespective as to whether it is a dielectric. Specifically
P(Minkowski) = n^2 * P(Abraham) where n is the refractive index, i.e. relative speed of light.
No other physical characteristics of the material enter into this formula.
It is intuitive that the speed of light in copper is very unlikely to be the same as the speed of light in vacuum, but it is best not to rely on intuition. Working through Maxwell's equations gives the phase velocity v of an EM wave in a conductor via
(1/v²)=(με/2)(1+√(1+σ²/(ω²ε²)))
Further, in a good conductor where σ≫ωε (as appears to me to be the case in copper at microwave frequencies) we can state that approximately:
v=√(2ω/σμ)
Using ω=2x10^10, σ=6x10^7, μ=12x10^-7 gives a value for v of circa 2.4*10^4, a very long way off c.
Hence my contention that it is worth exploring whether the Abraham/Minkowski controversy has any bearing on this problem.
R. -
#2272 by RERT on 12 May, 2016 11:21
-
#2273 by rfmwguy on 12 May, 2016 11:27
-
Drag weights! Hate having answers pop up in the middle of the night!NSF-1701A update -
Torsion pendulum modified at top clamp to improve stickiness. However, return to center still not up to my satisfaction, certainly worse than teeter totter balance. Seems torsion wire is temperature sensitive and perhaps needing to stabilize under weight some more. Have no return spring or anything to inhibit rotation except for oil bath. This dampens oscillations nicely but doesn't induce a return to center. Ideas on centering are welcome. Had thoughts of hanging a pair of vertical balance weights each with redirected force (small string) to horizontal and attach to beam directly opposite each other...reduces sensitivity but might help centering. Also noticed air currents really impact horizontal displacement. Bottom line is system noise must be no more than 50 micronewtons max, which was approximately what I had last time. This is a large setup:
Torsion wire: 24 inch drop of 0.030 inches to top of 14 inch tall central mast.
Coated Hardwood Beam: 107 inches total length, negligible vertical oscillation.
Support wires: from top of central mast to 14 inches in from each end.
Obviously much longer beam than most torsion setups. Can easily redo with smaller beam and less rotational end displacement. Wondering if that in itself would still have stickiness. Probably would but would be masked by far less rotational displacement.
Rfmw, could you describe or show the clamps or whatever is holding each end of the wire. There may be movement or friction at either end.
Anyway, I wire clamped each termination top and bottom. Think there was friction on the top one so redid it. Return to center is painfully slow with long beam and masses. So my solution is simple...just like me
Hang a pair of balancing weights supported independantly over beam near center point. This will apply slight drag to rotation either way but will force a rtc. Sort of a detent operation. Will experiment with different weights and placement and take a pic or video. Basically, the thing is too sensitive and the rtc was too slow...but you're right the top clamp was slipping a bit. -
#2274 by Gilbertdrive on 12 May, 2016 11:41
-
Here's where it gets difficult. The torsion wire test has a limitation...total mass. Having studied piano and related wire more than I care to, there are limits as to how many pounds of free weight you can hang on them. I think Yang had to use a 3 wire suspension system. Batteries are notoriously bulky and prone to outgassing or heating under load (center of mass change?). Neither one is good. Secondly, batteries need an inverter if a magnetron is used...not so for lower powered Solid State sources in the 30 Watt range or slightly above...but 900 Watts? Uhhh, not easy with batteries.
I guess those who say they would reject data from all off-board power systems would need to be very explicit in the objection, down to quantified data regarding the error it could create on a center-fed torsion test. Coaxial momentum beyond Lorentz and thermal distortion? Yeah, a new propulsion system
I might have to start a new thread on that one...not.
In fact, since Pr Yang has nullified preceding results, because of the heating of the wire, we know that the external Power supply can be an issue.
I do not reject all data of this type of setup. I just consider they are not a definitive proof. We can not content of that setup.
You are right, there are other issues with the batteries. I think they can be solved.
Maybe it would have been simpled with a magnetron from a 12V camping microwave, because no inverter needed. But it can probably achived with your 900W magnetron.
The important informations are :
-How much weight can you add without breaking your wire ?
-What is the peak Power of your Magnetron at startup ?
-Woould it work with a quasi-sinus, or does it needs pure sinus wave ?
With these 3 informations, I can give you an example of what is possible to do. -
#2275 by Rodal on 12 May, 2016 12:53
-
Dr.Rodal -
Rert,
Forgive me if I make another attempt to explain why I think that the Abraham-Minkowski debate may be relevant within a conductor.
I believe the arguments for differing momenta stem from the difference in the speed of light in a material, irrespective as to whether it is a dielectric. Specifically
P(Minkowski) = n^2 * P(Abraham) where n is the refractive index, i.e. relative speed of light.
No other physical characteristics of the material enter into this formula.
It is intuitive that the speed of light in copper is very unlikely to be the same as the speed of light in vacuum, but it is best not to rely on intuition. Working through Maxwell's equations gives the phase velocity v of an EM wave in a conductor via
(1/v²)=(με/2)(1+√(1+σ²/(ω²ε²)))
Further, in a good conductor where σ≫ωε (as appears to me to be the case in copper at microwave frequencies) we can state that approximately:
v=√(2ω/σμ)
Using ω=2x10^10, σ=6x10^7, μ=12x10^-7 gives a value for v of circa 2.4*10^4, a very long way off c.
Hence my contention that it is worth exploring whether the Abraham/Minkowski controversy has any bearing on this problem.
R.
Forgive me if I address what you propose, and investigate its consequences as to what it implies:
1) As I discussed, the Abraham Minkowski controversy is best discussed in terms of the basic quantities (the momentum)
which shows that the difference is only due to the values of the electric permittivity and the magnetic permeability. Since, as I discussed copper has real part values for both of these very close to those of vacuum, one rapidly concludes that there is no difference between Abraham and Minkowski for a conductive material like copper. And that's why you will not find anywhere in the 100 year long humongous literature of this controversy, what you propose. If you want to investigate this controversy you should do it with a dielectric like water, which has a relative electric permittivity value exceeding 80, instead of a material like copper that has a value of 1 (at GHz frequencies). Moreover, if anybody wanted to examine this controversy for a conductor (few people in the world do) they would investigate a conductor with high magnetic permeability, like a ferrite, instead of copper which has a value close to the one of vacuum.
2) Instead of expressing the Abraham Minkowski controversy in terms of electric permittivity and magnetic permeability you express it in terms of index of refraction, which leads to confusion, as I will show
3) Further, in order to figure out an index of refraction for copper, you discuss "an EM wave" and you come up with a phase velocity for this "EM wave". This is the main problem with your derivation: the equation you come up for the phase velocity, and its relevance to the problem at hand. (Your equation for the phase velocity for a plane wave is correct, but there is no such thing as a plane wave in a resonant cavity: a wave that is planar in infinite extent in space, that has the electric and magnetic fields perpendicular to the direction of propagation and where the electric and magnetic fields are perfectly in phase with each other. To start with, such a wave does not satisfy the boundary conditions at the copper interface, see proof here: http://forum.nasaspaceflight.com/index.php?topic=39214.msg1529920#msg1529920 ).
In your calculation you rounded numbers to one digit. Let's use a couple more digits:
ω=2 Pi 2.45*10^9 Hz = 1.539*10^10 Hz
σ=5.85x10^7
μ=1.257x10^-6
so, using your equation,
v=√(2ω/σμ)
one obtains
v=(20460 m/s) / (299792458 m/s)
= 6.825 *10^(-5) c
an extremely small phase velocity. The expression for the index of refraction is the inverse of this, so one computes with your formula, an index of refraction for copper of:
n=c/v = (299792458 m/s)/(20460 m/s)
=14651
So, according to your formula, the index of refraction of copper at 2.45 GHz is 14651
Now, let's go back to what mattered in the first place, which was the electric permittivity, instead:
The well known formula:
Therefore, the relative electric permittivity of copper, at 2.45 GHz, according to your formula is:
εr = n2 / μr
=(14651)2/1
=2.15*108
So, according to your formula, copper at 2.45 GHz has a relative electric permittivity that is 215 million times greater than the one of vacuum. Wow, that's quite a big difference.
(Note: this huge difference is due to the assumption that there is such a thing as an electromagnetic plane wave inside copper's skin depth).(*)
Rather than continue with this debate, and me having to say that your formula is incorrect, let's do this instead, "let's investigate RERT's assumption" as you propose:
for some time now, aero has been using a model for copper, and SeeShells frequently posts the Meep results, based on NSF member DeltaMass, that uses a value of relative electric permittivity for copper of 1 at GHz frequencies.
To investigate "RERT's assumption", how about if aero multiplies the value he uses for the real part of the electric permittivity by 215 million times, to reproduce the value of 2.15*108 that you favor instead.
Then, let's compare the results, for quality factor of resonance, electromagnetic fields, etc., to ascertain how close to reality is RERT's model for copper as compared to DeltaMass' model (where RERT's model uses a value of relative electric permittivity that is 215 million times greater than the value recommended by DeltaMass)
_________________
(*) Maxwell's equations are partial differential equations. A solution to a partial differential equation is a solution that meets the boundary conditions of the problem. A plane electromagnetic wave is a travelling wave. No single travelling wave can satisfy the boundary conditions: you have essentially 1 micrometer of skin depth over which you have to satisfy that the electric field in the direction parallel to the surface must be very small and that the electromagnetic fields have to decay exponentially (eventually to zero) such that at the skin depth they decay by e^(-1). The plane wave you propose does not satisfy these boundary conditions, and that is why it gives such exhorbitant values: it is not a possible solution. Shawyer similarly proposes single travelling waves inside the EM Drive, in addition to standing waves. Shawyer's single travelling waves cannot meet the boundary conditions of the problem. One could have cauliflower waves: but it they do not meet the boundary conditions one must rule out any such solution that does not meet the boundary conditions.
Not addressing the boundary conditions means NOT solving Maxwell's equations.
(**) Is there a difference between copper and vacuum? Yes, the important difference is in the imaginary parts of the permittivity, it is the loss tangent (tan δ) that has a huge value, while the vacuum (as far as we know) does not have a significant value of the loss tangent. Thus the difference between them at microwave frequencies is not in the real part of the index of refraction, but it is instead in the imaginary part of the index of refraction.
What is the practical consequence of this difference? It is the power loss in the copper: HEAT, as the power is dissipated into HEAT.
If somebody can explain how the power loss in the copper can be translated into momentum to the cavity (other than by thermal effects like: thermal convection, thermal radiation and thermal expansion), now that would be interesting!
-
#2276 by Rodal on 12 May, 2016 13:13
-
http://cannae.com/another-successful-superconducting-demo-completed/
I note:
1) the torsional pendulum is not used for Cannae's superconducting "tests"
2) batteries are not used for Cannae's superconducting "tests"
3) vacuum chamber is not used for Cannae's superconducting "tests"
in other words the same testing method is not used for Cannae's superconducting "tests" which purport to use no polymer insert as the tests with normal conductors that use polymer inserts.
Hence, the purported "no need for polymer inserts" for Cannae's superconducting "tests" is due to the different testing method.
Different testing methods ==> different results. Same story as in the tests that were nullified by Yang: when Yang did not use batteries and no polymer insert, she also obtained "thrust", when she used batteries, she obtained no thrust.
Somebody will say, but, but, but I cannot use the same testing method because
..., well, then it is on your shoulders to show the audience that your cord is not moving the spoon (not on the shoulders of the audience that are asked to disregard that there is a cord attached to the spoon)
-
#2277 by OttO on 12 May, 2016 13:31
-
Dr.Rodal -
Forgive me if I make another attempt to explain why I think that the Abraham-Minkowski debate may be relevant within a conductor.
I believe the arguments for differing momenta stem from the difference in the speed of light in a material, irrespective as to whether it is a dielectric. Specifically
...
Hence my contention that it is worth exploring whether the Abraham/Minkowski controversy has any bearing on this problem.
R.
Just for info (I am not going to debate you could take a look at the paper:
Photon momentum and optical forces in cavities
http://proceedings.spiedigitallibrary.org/proceeding.aspx?articleid=2501661#
Try the download link at the bottom left.
-
#2278 by rfmwguy on 12 May, 2016 13:32
-
***Science Writers Alert***
Looks like we might know something today or tomorrow according to the agenda:
(On second thought, a young South African student designing, building and demonstrating the EMDrive and winning a trip to the USA this week and being eligible for a share in $4 Million Prize Money is a pretty cool press release).
Good Luck to Paul from South Africa this week in Phoenix at the Intel International Science and Engineering Fair (Intel ISEF 2016)!
"Name: Paul Stansell
Location: Johannesburg, South Africa
School Represented: Sacred Heart College
Student Showcase: Electric Space Propulsion – An Exploration into Innovative Propellant Solutions Involving the Testing of an Electromagnetic Drive
Study Synopses: Since its birth, spaceflight has always been hindered by propellant constraints. Unfeasible amounts of fuel are required to cover the vast distances between stars and so modern spaceflight is confined to the solar system. A revolutionary electric propulsion system, according to Stansell, composed of a hollow asymmetric resonant cavity excited by microwaves, known as the EMDrive has been shown to produce a unidirectional acceleration although results have been inconclusive. This warrants further research.
According to Stansell a non-resonant EMDrive was constructed to act as a control, this design was then extended to create a new cavity which allowed for resonance at a frequency of 2450 MHz. The designs were tested in both the upright and inverted orientations to allow for EMDrive force separation from buoyant forces. The designs were tested on a millinewton resolution knife-edge fulcrum which was calibrated to accurately determine thrust magnitude.
Stansell revealed that due to thermal currents caused by the heating of the magnetron and cavity, each test experienced net upwards motion. However the resonant upright cavity moved upwards considerably more than the non-resonant control suggesting another force was at work pushing the cavity upwards. Additionally the resonant inverted test moved upwards considerably less than the control again indicating another force was counteracting the net upwards motion. This force varied in magnitude from 8.8825 millinewtons 11.8436 millinewtons.
In conclusion, according to Stansell, despite thermal current interference a replicable, anomalous thrust was produced. As the observed thrust is not yet attributable to any known physical phenomenon more research in vacuum is required."
(snip)
The final Intel ISEF 2016 winners will be announced, by Intel, during the course of the week.
http://www.itnewsafrica.com/2016/05/africa-has-strong-showing-at-intel-isef-2016/
More from: https://student.societyforscience.org/intel-isef
About Intel ISEF
The Intel International Science and Engineering Fair (Intel ISEF), a program of Society for Science & the Public (SSP), is the world’s largest international pre-college science competition.
Approximately 1,700 high school students from over 75 countries, regions, and territories are awarded the opportunity to showcase their independent research and compete for approximately $4 million in prizes.
Today, millions of students worldwide compete each year in local and school-sponsored science fairs; the winners of these events go on to participate in SSP-affiliated regional and state fairs from which the best win the opportunity to attend Intel ISEF.
Intel ISEF unites these top young scientific minds, showcasing their talents on an international stage, where doctoral level scientists review and judge their work.
SSP partners with Intel—along with dozens of other corporate, academic, government and science-focused sponsors—who provide the support and awards for Intel ISEF.
Intel ISEF is hosted each year in a different city (Los Angeles, Pittsburgh and Phoenix through 2019). The Local Arrangements Committees from each city partner with SSP and Intel to provide support for the event including the recruitment of 100s of volunteers and judges and in organizing an education outreach day in which more than 3,000 middle and high school students visit.
UPCOMING DATES AND LOCATIONS FOR INTEL ISEF
Phoenix, Arizona, May 8-13, 2016
Thursday, May 12, 2016
10:00 a.m. – 2:00 p.m. ALL FINALISTS MUST BE AT PROJECTS
7:00 p.m. – 10:00 p.m. Special Awards Ceremony
Friday, May 13, 2016
9:00 a.m. – 11:30 a.m.* Intel ISEF Grand Awards Ceremony -
#2279 by Gilbertdrive on 12 May, 2016 13:48
-
http://cannae.com/another-successful-superconducting-demo-completed/
I note:
1) the torsional pendulum is not used for Cannae's superconducting "tests"
2) batteries are not used for Cannae's superconducting "tests"
3) vacuum chamber is not used for Cannae's superconducting "tests"
in other words the same testing method is not used for Cannae's superconducting "tests" which purport to use no polymer insert as the tests with normal conductors that use polymer inserts.
Hence, the purported "no need for polymer inserts" for Cannae's superconducting "tests" is due to the different testing method.
Different testing methods ==> different results. Same story as in the tests that were nullified by Yang: when Yang did not use batteries and no polymer insert, she also obtained "thrust", when she used batteries, she obtained no thrust.
Somebody will say, but, but, but I cannot use the same testing method because ..., well, then it is on your shoulders to show the audience that your cord is not moving the spoon (not on the shoulders of the audience that are asked to disregard that there is a cord attached to the spoon)
I agree... with just a precision concerning the magnitude of the thrust.
If instead of a spoon, I have a cargo ship attached with a cord to my finger, and that I make it move and leaves the water
my spectators will find it impressive.
If the thrust mesured by Cannae was of one ton, for example, as it is advanced for Shawyer superconducting drive, even with external power, it would be very interesting.
I think that when they Tested the RocketDyne F-1 motors on ground, they did not need to make a all inclusive package, with propellant on board and batteries.
Does somebody knows how much thrust they got ? It do not see it on the link.
)
I might have to start a new thread on that one...not.
..., well, then it is on your shoulders to show the audience that your cord is not moving the spoon (not on the shoulders of the audience that are asked to disregard that there is a cord attached to the spoon)
my spectators will find it impressive.