-
#2580 by gustavo on 18 May, 2016 20:52
-
The studies were made considering a continuous beam of photons being reflected inside a truncated cone cavity.
Great work! Two things: 1. Can you fun the simulation for a truncated cone with rounded endplates with the same center radius? 2. Suggest also running the simulation with the laser firing less randomly and more like the angle shown in this image.
Monomorphic, to simulate the case of a truncated cone with rounded endplates, I must first find the correct equations for the boundary condition of the rounded endplates. This should take a few days to put on code. But it was already planned. When I finish the algorithm with the modified code for rounded ends, I'll post here the results. Thanks for the tip.
In relation to the laser firing angle and position, apparently it makes a lot of difference in the resultant thrust, I've tested several initial conditions for the same cavity dimension and the resulting thrust was different in each case.
-
#2581 by FattyLumpkin on 18 May, 2016 21:15
-
Dr. Rodal, thank you for your reply! Re the NASA frustum is there an ideal location for exciting TE012?, and would going with a larger frustum (say x2 larger), with a much higher Q, help in "locking down" the mode? FL
-
#2582 by Rodal on 18 May, 2016 21:26
-
Dr. Rodal, thank you for your reply! Re the NASA frustum is there an ideal location for exciting TE012?, and would going with a larger frustum (say x2 larger), with a much higher Q, help in "locking down" the mode? FL
1) What matters is the location of the excitation loop. It should be located preferentially where the magnetic field intensity is highest, and where its gradient is minimum (so that positioning is not as critical), and located precisely so that it is aligned as well as possible with the direction of the magnetic field. The loop has to be made precisely and aligned precisely (the alignment is not that easy to achieve). As to the best location it depends on the geometry of the fustrum (the conical angle and the spherical radial distance to the apex of the small and large ends). X-Ray conducted some studies in the past (sorry it would take me too long to search for those links, no good way to search massive threads at NSF.)
Looking forward to further advise from X-Ray, Monomorphic, Aero, SeeShells and TheTraveller in this regard.
2) Making the cavity larger would not help significantly with the excitation problem, what matters most is stated in #1 above.
3) Presence of other mode shapes in the vicinity (discussed by Dr. White) maybe important if the other modes nearby are also TE modes with similar magnetic fields. -
#2583 by Monomorphic on 18 May, 2016 21:50
-
Just my luck. The RF Instruments spectrum analyser sold out just one hour before I whipped out my credit card to make the purchase. I have an email into them to see when another batch will be ready.
http://www.ebay.com/itm/USB-RF-Spectrum-Analyzer-3-3GHZ-/282009631423 -
#2584 by dustinthewind on 18 May, 2016 21:58
-
...here the maximum Blongitudinal field intensity occurs, to try to excite the axial magnetic field that takes place in the longitudinal direction with a TE mode. ...
So this image of the antenna here would be the optimal location to excite the TE012 mode? Am I right that the loop perimeter is half the wavelength of the current in the wire? Wires twisted when not in loop to eliminate B field generation. Image from Dr. Rodals pic of TE012, screen shot, then doodled over in paint.
I wonder if phase drifting in a signal generator might be problematic for keeping power in the cavity. i.e. the antenna would become out of phase with the current in cavity.
-
#2585 by Rodal on 18 May, 2016 22:19
-
Somewhere on the axis of axisymmetry where the gradient is smallest for that geometry (for that cone angle and for that spherical radii to the big and small D)...here the maximum Blongitudinal field intensity occurs, to try to excite the axial magnetic field that takes place in the longitudinal direction with a TE mode. ...
So this image of the antenna here would be the optimal location to excite the TE012 mode? Am I right that the loop perimeter is half the wavelength of the current in the wire? Wires twisted when not in loop to eliminate B field generation. Image from Dr. Rodals pic of TE012, screen shot, then doodled over in paint. -
#2586 by Rodal on 18 May, 2016 22:23
-
My studies on the EmDrive based on Ray Tracing is done, paper is attached.
In paper it is described how the algorithm was made, and it is discussed some results obtained for some cases.
I'm running some simulations now with higher number of iterations (reflections), but it will take a longer time to get the results. Still with some issues with preallocating memory on the algorithm.
The studies were made considering a continuous beam of photons being reflected inside a truncated cone cavity.
The asymmetry of the cone geometry causes an imbalance in the angle of incidence between the two ends, which I believe is the main cause for the resulting net thust. Calculations with a geometry of a cylinder resulted in zero thrust.
Thrust is towards small end.
Your results (a thrust force for a given amount of input power 1.26 mN/kW, way in excess of a perfect photon rocket=0.003336 mN/kW) clearly violate both conservation of momentum and conservation of energy, and they do so without the resort to any New Physics, just based on the ray tracing method for a large number of reflectances.
Your solution depends on a large number of numerical calculations with finite precision. Due to round-off conservation of momentum and energy may be unenforced in each calculation.
It would be more convincing if conservation of momentum and energy would be enforced by a side-condition such as not to allow momentum or energy to unconserved by more than an insignificant amount.
Otherwise, the first thing that I would ask is: how do you explain the lack of conservation of momentum and conservation of energy?
The first thing I would look to is the conditioning of your solution matrix. Is it ill-conditioned? Have you looked at the relative size of all its diagonal members?
What is the value of
for your solution matrix throughout the calculations?
Can you plot kappa from the first calculation to the end ? What does it look like? -
#2587 by SeeShells on 18 May, 2016 22:46
-
Just my luck. The RF Instruments spectrum analyser sold out just one hour before I whipped out my credit card to make the purchase. I have an email into them to see when another batch will be ready.
http://www.hamradio.com/detail.cfm?pid=H0-013596
http://www.ebay.com/itm/USB-RF-Spectrum-Analyzer-3-3GHZ-/282009631423
Maybe look here, where I got mine.
Shell -
#2588 by Monomorphic on 18 May, 2016 23:40
-
Just my luck. The RF Instruments spectrum analyser sold out just one hour before I whipped out my credit card to make the purchase. I have an email into them to see when another batch will be ready.
http://www.hamradio.com/detail.cfm?pid=H0-013596
http://www.ebay.com/itm/USB-RF-Spectrum-Analyzer-3-3GHZ-/282009631423
Maybe look here, where I got mine.
Shell
I ordered the miniVNA and it is on its way from Virginia. The spectrum analyser is what sold out.
-
#2589 by gustavo on 18 May, 2016 23:40
-
Your results (a thrust force for a given amount of input power, in excess of a perfect photon rocket) clearly violate both conservation of momentum and conservation of energy.
What about the conservation of momentum and the thrust measured in EmDrive experiments?
For a given cavity dimension and beam initial trajectory, there must be a certain number of reflections until the "path loop" is closed so the thrust returns to zero, keeping the conservation of momentum.
Image attached shows a case where thrust has returned to zero after approximately 110,000 reflections:
This means that for a beam being continuously reflected inside a cavity, thrust would be cyclic, and returns to zero every time the path loop for conservation of momentum is closed. But, if a beam is reflected and absorbed before the path loop is closed, net thrust is observed.
Yet this does not explain thrust higher than a photon rocket of same power.
I've checked the equations in the algorithm, everything seems right.Your solution depends on a large number of numerical calculations with finite precision. Due to round-off conservation of momentum and energy may be lost in each calculation.
Cylinder case is still giving zero thrust after 250,000 iterations, as expected, I have checked the resulting thrust variable value, zero, round-off is not being a problem.It would be more convincing if conservation of momentum and energy would be enforced by a side-condition, after every few calculations.
The first thing I would look to is the conditioning of your solution matrix. Is it ill-conditioned? Have you looked at the relative size of all its diagonal members?
What is the value of
for your solution matrix throughout the calculations?
Can you plot kappa from the first calculation to the end ? What does it look like?
I will look into it.
Thanks for your notes Dr. Rodal.
-
#2590 by Rodal on 19 May, 2016 00:00
-
Actually the image attached with a return to zero reinforces my opinion.Your results (a thrust force for a given amount of input power, in excess of a perfect photon rocket) clearly violate both conservation of momentum and conservation of energy.
What about the conservation of momentum and the thrust measured in EmDrive experiments?
For a given cavity dimension and beam initial trajectory, there must be a certain number of reflections until the "path loop" is closed so the thrust returns to zero, keeping the conservation of momentum.
Image attached shows a case where thrust has returned to zero after approximately 110,000 reflections:
This means that for a beam being continuously reflected inside a cavity, thrust would be cyclic, and returns to zero every time the path loop for conservation of momentum is closed. But, if a beam is reflected and absorbed before the path loop is closed, net thrust is observed.
Yet this does not explain thrust higher than a photon rocket of same power.
I've checked the equations in the algorithm, everything seems right.Your solution depends on a large number of numerical calculations with finite precision. Due to round-off conservation of momentum and energy may be lost in each calculation.
Cylinder case is still giving zero thrust after 250,000 iterations, as expected, I have checked the resulting thrust variable value, absolute zero, round-off is not being a problem.It would be more convincing if conservation of momentum and energy would be enforced by a side-condition, after every few calculations.
The first thing I would look to is the conditioning of your solution matrix. Is it ill-conditioned? Have you looked at the relative size of all its diagonal members?
What is the value of
for your solution matrix throughout the calculations?
Can you plot kappa from the first calculation to the end ? What does it look like?
I will look into it.
Thanks for your notes Dr. Rodal.
It looks like a random walk in several dimensions.
Random walks are known to return to zero. In your case you may have a random walk in 3 dimensions, which is well known to have a probability of returning to zero of only about 34% of the cases.
Also the behavior you describe for the cavity with constant circular cross-section reinforces my opinion, as it describes a simpler kind of random walk than the truncated cone. It is well known that almost surely there will be a return to the origin in a 2-dimensional random walk, but for 3 dimensions or higher, the probability of returning to the origin decreases as the number of dimensions increases. In 3 dimensions, the probability of returning to the origin decreases to roughly 34%
Also, the biggest concern should be for conservation of energy, as what you have in your computation is a free-energy machine. You could run a computation with 2 EM Drives rotating: if the force/InputPower is that much higher than a photon rocket you will be producing a large amount of excess energy by having 2 EM Drives rotating and generating power. Just think of how much more useful this would be here on Earth to solve the energy crisis (rather than a rocket in space breaking conservation of momentum): no more deforestation of the Amazon, no need for having cars in Brazil running on biofuels, if the EM Drive would indeed be a free-energy machine.
Yes, a free-energy machine sounds too good to be true: it requires further inspection of the nature of your solution and its implications, I think you will agree. -
#2591 by FattyLumpkin on 19 May, 2016 00:01
-
Dr. Rodal, at the end of the Ames talk Sonny describes moving forward and mentions "phase lock loop", forgive my high school physics only, but would phase lock looping eliminate or mitigate the issues associated with modes being too "close" to one another? Not to mention your above mentioned antenna looping and positioning advice. Your help is greatly appreciated. FL (below attached image of "moving forward" frustum)
-
#2592 by Rodal on 19 May, 2016 00:03
-
Dr. Rodal, at the end of the Ames talk Sonny describes moving forward and mentions "phase lock loop", forgive my high school physics only, but would phase lock looping eliminate or mitigate the issues associated with modes being "close" to one another? Not to mention your above mentioned antenna looping and position. Your help is greatly appreciated. FL (below attached image of "moving forward" frustum)
I will be at a University during the next few days, will see when I can get to this -
#2593 by meberbs on 19 May, 2016 00:31
-
My studies on the EmDrive based on Ray Tracing is done, paper is attached.
Thank you for posting this paper.
In paper it is described how the algorithm was made, and it is discussed some results obtained for some cases.
...
I started going through your equations and found an issue with your definition of the normal vector for the sidewalls.
I believe the correct expression should be
[-x/R * cos(Φ) , -y/R * cos(Φ), sin(Φ)]
This expression is also written in a form that should always be normalized as long as x^2 +y^2 = R^2.
The mistake vanishes when Φ = 0, explaining why you got the expected result for a cylinder. This flows into your other calculations, so I will let you correct this before I review the other technical details more thoroughly. -
#2594 by gustavo on 19 May, 2016 00:58
-
My studies on the EmDrive based on Ray Tracing is done, paper is attached.
Thank you for posting this paper.
In paper it is described how the algorithm was made, and it is discussed some results obtained for some cases.
...
I started going through your equations and found an issue with your definition of the normal vector for the sidewalls.
I believe the correct expression should be
[-x/R * cos(Φ) , -y/R * cos(Φ), sin(Φ)]
This expression is also written in a form that should always be normalized as long as x^2 +y^2 = R^2.
The mistake vanishes when Φ = 0, explaining why you got the expected result for a cylinder. This flows into your other calculations, so I will let you correct this before I review the other technical details more thoroughly.
Actually, I made a mistake while writing the equation on paper, z component of n is not R(z)*sin(Φ), it is R(z)*tan(Φ), which was already correct on the algorithm as you can see on paper. I have uploaded the paper with this correction.
I believe that this is the correct expression
[-x , -y, R(z)tan(Φ)]
Which is further normalized in the algorithm,
I have tried with your expression: [-x/R * cos(Φ) , -y/R * cos(Φ), sin(Φ)], and thrust is still present.
How did you get this expression?
-
#2595 by jmossman on 19 May, 2016 01:01
-
Dr. Rodal, at the end of the Ames talk Sonny describes moving forward and mentions "phase lock loop", forgive my high school physics only, but would phase lock looping eliminate or mitigate the issues associated with modes being too "close" to one another? Not to mention your above mentioned antenna looping and positioning advice. Your help is greatly appreciated. FL (below attached image of "moving forward" frustum)
Hopefully Dr.Rodal won't mind a member of the NSF "hive mind" answering your question.
A "phase lock loop" does help in maintaining a constant output frequency. Unfortunately one of the biggest problems seen with these DIY resonant cavities is thermally induced deformation. In other words, the longer one injects RF energy, the hotter the cavity becomes, which in turn causes uneven heating and deforms the shape of the cavity.
If the cavity were a constant shape (i.e. if the walls were made thick enough, joints reinforced, advanced thermal management, etc), then a phase lock loop and appropriate amplifier could indeed be used to help select between the nearby "modes" (assuming proper antenna type, position, and orientation). Unfortunately, as the cavity's shape changes, so can the frequency of each "mode". A constant frequency won't help much if the desired "mode" frequency keeps drifting due to the cavity changing shape.
A fancy control algorithm might help if the cavity could be characterized at multiple temperatures, and the cavity monitored closely enough during RF injection, but not an easy task. I believe TheTraveller is contemplating such a feedback loop.
IIRC, Monomorphic has been running lots of simulations and altering his cavity geometry to try and provide a larger frequency "gap" between his desired excitation mode and the neighboring undesired mode(s). -
#2596 by Monomorphic on 19 May, 2016 01:03
-
Reply from RF Instruments: "We relisted and should be back on ebay in 24 hours."
Okay, not too long to wait, but that means it won't get here until next week. -
#2597 by dustinthewind on 19 May, 2016 01:08
-
Dr. Rodal, at the end of the Ames talk Sonny describes moving forward and mentions "phase lock loop", forgive my high school physics only, but would phase lock looping eliminate or mitigate the issues associated with modes being too "close" to one another? Not to mention your above mentioned antenna looping and positioning advice. Your help is greatly appreciated. FL (below attached image of "moving forward" frustum)
This might help a bit: . The one I used compared two signals and let me know if they were matched in phase with a meter that measures the voltage on a capacitor. They can be used to also look at very small signals hidden in noise and I am sure more.
I would suspect the use for the phase lock with the cavity would possibly be to use two antenna's. One antenna would be a sensing antenna to check the phase/frequency of the signal inside the cavity. This can then be compared to the voltage of the driving antenna to make sure the input antenna is still in phase with the cavity.
I could also speculate that if the EM drive is producing a force that a PLL might be used to listen for that force. A very small force could be filtered out of noise to listen for only the force impulse at (a known frequency) using low power levels inside the EM drive.
I would think one major remaining problem might still be thermal thrust, unless it has been eliminated but maybe its not as much of an issue at very low power levels. Maybe even the force impulse could match a resonant frequency of a hanging pendulum, or force against a pezio-electric crystal or some sensitive pressure sensor.
Maybe a pendulum (with resonant frequency) with cavity suspended, holding a large capacitor plate (vertically) and suspended by a voltage at equilibrium perpendicular to gravity. An applied force changes the capacitance allowing more/less charge to be on the capacitor for a set voltage causing a current flow that can be measured. (Or hold charge constant changing the voltage on the capacitor instead). Noise can be filtered out by phase locking to the impulse frequency which is also at the pendulum resonant frequency? -
#2598 by meberbs on 19 May, 2016 03:27
-
My studies on the EmDrive based on Ray Tracing is done, paper is attached.
Thank you for posting this paper.
In paper it is described how the algorithm was made, and it is discussed some results obtained for some cases.
...
I started going through your equations and found an issue with your definition of the normal vector for the sidewalls.
I believe the correct expression should be
[-x/R * cos(Φ) , -y/R * cos(Φ), sin(Φ)]
This expression is also written in a form that should always be normalized as long as x^2 +y^2 = R^2.
The mistake vanishes when Φ = 0, explaining why you got the expected result for a cylinder. This flows into your other calculations, so I will let you correct this before I review the other technical details more thoroughly.
Actually, I made a mistake while writing the equation on paper, z component of n is not R(z)*sin(Φ), it is R(z)*tan(Φ), which was already correct on the algorithm as you can see on paper. I have uploaded the paper with this correction.
I believe that this is the correct expression
[-x , -y, R(z)tan(Φ)]
Which is further normalized in the algorithm,
I have tried with your expression: [-x/R * cos(Φ) , -y/R * cos(Φ), sin(Φ)], and thrust is still present.
How did you get this expression?
With the correction to tan(Φ) the expressions produce a vector with the same direction, mine is just normalized already. Multiply mine by R/cos(Φ) to see that they are equivalent. I'll look into the rest later. -
#2599 by Tellmeagain on 19 May, 2016 05:35
-
My studies on the EmDrive based on Ray Tracing is done, paper is attached.
In paper it is described how the algorithm was made, and it is discussed some results obtained for some cases.
I'm running some simulations now with higher number of iterations (reflections), but it will take a longer time to get the results. Still with some issues with preallocating memory on the algorithm.
The studies were made considering a continuous beam of photons being reflected inside a truncated cone cavity.
The asymmetry of the cone geometry causes an imbalance in the angle of incidence between the two ends, which I believe is the main cause for the resulting net thust. Calculations with a geometry of a cylinder resulted in zero thrust.
Thrust is towards small end.
A friend asked me to review this manuscript by gustavo Colheri Uchida. Attached please find my review report. Thanks!
