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#3360
by
RERT
on 29 Jun, 2016 22:44
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Criticism both constructive and non-constructive have pushed the DIY testers into safe spaces.
Why does nothing happen in the first part of the 100% cycle? Why does it stop moving on the other cycles before power is cut? Why are there plateaus and valleys in the cooling cycle - is something physically deforming due to thermals in the test setup? link Hopefully he continues testing as he stated, unlike his first paper he released, and he measures his error terms.[/b]
You can't deduce much from a glance. The system has more than one natural frequency, so oscillation at a high frequency can interfere with movement at a lower frequency. There is significant damping and inertia (my estimate from having looked hard at other intermediate data from RFMWGUY), and so the rise during power-on is slow. Also, the mechanism seems very mechanically 'sticky'.
It would be crazy to argue that error-bars are not needed on a claimed force measurement. I think it's also quite hard to do!
I don't think you can deduce easily the instantaneous force on the beam without a mechanical model which matches the power-off characteristics. I'm working on that, based on previous data. I think RFMWGUY could blow much of this criticism away by showing reversed thrust with reversed frustrum orientation. Meanwhile, I think the jury is out on whether these are thermal or thrust effects. It is beyond doubt, from just this chart, that there is
something moving the beam during power-on.
FWIW I don't think RFMWGUY has a problem with technical criticism, I think he left because of other behaviours from senior people here. To our loss, obviously. I think the actions which drove him away have not, ultimately, been in the interests of this site, and I would encourage anybody with influence to try and get him back.
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#3361
by
Monomorphic
on 29 Jun, 2016 23:05
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Criticism both constructive and non-constructive have pushed the DIY testers into safe spaces.
No constructive criticism pushed DIYers anywhere. It was the very poor moderation on a certain forum (not NSF). We shouldn't be subjected to constant pejoratives and insults from from professional trolls. Dave and TT were constantly ridiculed, Shell was subjected to vile sexist comments, and I was called names and a liar about being a builder as recently as a week ago.
If Eric1600 wants to participate in the new subreddit, he can message me and ask, but he needs to tone it down and remain cordial. This message is not typical of his responses to Dave and others. He's usually very condescending.
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#3362
by
meberbs
on 30 Jun, 2016 01:01
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I am not seeing anything in rfmwguy's data that looks like a positive signal. Half of the signal does not return to 0 on power off, and the peaks are not proportionate to the power level.
I am not sure what is happening (obviously something is). One of his comments on twitter seems to indicate things return to 0 after they cool off. This gives me the impression that thermal expansion (or other thermal related effects) is likely behind most or all of the signal.
To anyone who wants to make absolute claims about what this result shows (whether real signal or blaming Lorentz): Please make it clear that it is only your speculation. We don't have enough information to extract what happened, and clearly there are confounding issues, such as the not returning to 0.
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#3363
by
zen-in
on 30 Jun, 2016 01:51
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I am not seeing anything in rfmwguy's data that looks like a positive signal. Half of the signal does not return to 0 on power off, and the peaks are not proportionate to the power level.
I am not sure what is happening (obviously something is). One of his comments on twitter seems to indicate things return to 0 after they cool off. This gives me the impression that thermal expansion (or other thermal related effects) is likely behind most or all of the signal.
To anyone who wants to make absolute claims about what this result shows (whether real signal or blaming Lorentz): Please make it clear that it is only your speculation. We don't have enough information to extract what happened, and clearly there are confounding issues, such as the not returning to 0.
I agree with most of what you stated and think lorentz force is not present. It would be useful to have a look at the calibration waveforms. They should be like a second order step response- a steep rise time with overshoot and some ringing. The amount of overshoot and ringing does depend on the damping effects of the oil damper. Maybe if multiple calibration waveforms were acquired at different damping levels (by adjusting the size of the paddle in the oil bath) a good picture of the system response of this pendulum could be obtained. the waveform from a Lorentz forces or any actual EM-drive force will have a very similar shape. I don't see a second order response in those waveforms. I might be wrong since I haven't seen the calibration waveforms. It does look they have an exponential rise and fall which is indicative of a first order system; ie: thermal. More data is needed.
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#3364
by
mikegem
on 30 Jun, 2016 03:07
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Apologies if my post indicates ignorance due to not being able to read here as often as I'd like.
Re rfmwguy's recent results:
Has unknown mechanical hysteresis been ruled out as a contributor to the apparent non-return to zero?
One way to do this would be to mechanically deflect (no power to magnetron, i.e., no EM test) to at least the largest indicated deflection, then release and see if the deflection returns to zero. If yes, mechanical hysteresis is a less likely participant. If no, time for mechanical detective work.
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#3365
by
FattyLumpkin
on 30 Jun, 2016 05:10
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Monomorphic, have you reloaded FEKO yet? Am hoping you'll have time to perform a few sims for me on the 2007-2008 Cannae geometry (which is very different from their current design). I also have more exacting dimensions for the geometry you performed a sim on, that I believe you said you had to "guess" about.
Thanks , FattyLumpkin PS: will return with 1st image once I hear from you. Ciao!. K
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#3366
by
keithpickering
on 30 Jun, 2016 06:42
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keithpickering , would you please explain more about surface to volume ratio and it's relationship to the Q of a cavity. Please use these figures: flattened frustum S/V is
4362 cm2 / 8835 cm3. Original geometry NASA frustum S/V ratio is 2438 cm2 / 8835 cm3.
Thank you, FL
FL,
The previously cited post from Dr. Rodal answers that rather concisely; the upshot is, the larger the cavity the bigger the Q. Which might be useful during design, assuming you're not using MEEP or equivalent software. That result should be fairly intuitive anyway, since in larger cavities a photon will fly farther before hitting a wall, and Q is measured in relation to the frequency. In other words, you're going to get more waves before hitting a wall with a larger cavity, hence fewer chances at absorption per wavelength.
For cylinders and rectangular boxes, equations for Q are available, but for non-standard shapes like frusta, you will need to actually measure to be sure.
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#3367
by
A_M_Swallow
on 30 Jun, 2016 08:00
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Heating effects can be tested by using a none resonant frequency and comparing the differences.
A nozzle whose direction can be changed could be added to a frustrum to show the effects of air jets.
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#3368
by
Chrochne
on 30 Jun, 2016 09:13
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Without a healthy balance of strong criticism it is easy to mislead yourself into a conclusion, become emotionally attached, and then defend it irrationally. People eager to believe the results will only re-enforce this desire to believe the conclusions are correct. However if you can't quantity the error contributors, you can't prove anything anomalous exists. And this trend for safe spaces is a bad thing overall.
[/quote]
I can not agree with that phase "healthy strong criticism". Criticism is never healthy. It most of the times is there just to bluntly point out what you do is wrong. It is especialy strong in these terms from the people that do not believe that this device work. That kind of criticism would never be neutral.
I think that in his criticism Eric should also point this fact out. This way he only negates everything other side do.
Mod: I deleted my previous post as some critics here found it too much critical of others in order to keep this debate healthy.
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#3369
by
JohnFornaro
on 30 Jun, 2016 12:17
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Criticism is never healthy.
One is certainly free to express and hold this uniquely binary viewpoint about experimentation. After all, they designed 'safe spaces' in order to maximize the echo chamber effect for those people who prefer no criticism at all.
Either the experimental device works or it doesn't. Either the experimenter understands why, or else the experimenter doesn't understand why.
So far, the reported experiments haven't floated a device across the conference table at the investor meeting.
It is generally 'safe' to ignore trolls who denigrate one's work in uncharitable terms. Do not feed the trolls, and the site bandwidth will be saved from unnecessary personal nonsense.
Again, one is free to ignore helpful criticism. good luck with that approach.
Finally, many thanks above for the "learn something new every day" moment regarding Lilith. The John Collier painting of her shown on the oracle is inspiring.
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#3370
by
dustinthewind
on 30 Jun, 2016 16:03
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Heating effects can be tested by using a none resonant frequency and comparing the differences.
A nozzle whose direction can be changed could be added to a frustrum to show the effects of air jets.
I am not sure a non-resonant frequency will heat the cavity. If the energy doesn't resonate in the cavity it may instead reflect back into a heat dump the engineers designed to protect the excitation device such as a magnetron or clystron from taking that energy on a non-resonant frequency. The heat comes from the currents in the cavity being excited to move in certain patterns which doesn't happen if it doesn't resonate. The patterns even change depending on the resonant mode.
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#3371
by
SeeShells
on 30 Jun, 2016 18:28
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Heating effects can be tested by using a none resonant frequency and comparing the differences.
A nozzle whose direction can be changed could be added to a frustrum to show the effects of air jets.
I am not sure a non-resonant frequency will heat the cavity. If the energy doesn't resonate in the cavity it may instead reflect back into a heat dump the engineers designed to protect the excitation device such as a magnetron or clystron from taking that energy on a non-resonant frequency. The heat comes from the currents in the cavity being excited to move in certain patterns which doesn't happen if it doesn't resonate. The patterns even change depending on the resonant mode.
Just on for a bit catching up but I wanted to post and give a "like" to this statement. The microwaves will "bounce" off the non-resonating wall (phasing missmatch) in the frustum and be reflected back into a "load" or back into the magnetron or SS device and not be absorbed into the frustum chamber to be finally dissipated as heat in the Txx mode of operation. This is known as also known as the VWSR or Voltage Standing Wave Ratio.
I found it quite interesting that in rfmwguy's video of the thermal profile that the small endplate heated up quickly when powered by the magnetron.
The reason for not seeing a mode develop in the endplate could be due the the masking and blurring by the thermal conductivity of the copper plates and or by the non stability of the mode generated.
Take a look at in FEKO with of one of my design builds where the incoming signal shifted through one cycle and see how the modes fluctuated internally.
It is a Betty Crocker RF mixer even with a clean digital RF source.
Shell
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#3372
by
SeeShells
on 30 Jun, 2016 18:53
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This is a gif frequency sweep in FEKO. The thing to look for is the cavity lock where the energy that's held in the dual waveguides let's itself into the frustum showing a decreased VSWR in the waveguide.
Shell
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#3373
by
D_Dom
on 30 Jun, 2016 19:52
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It is a Betty Crocker RF mixer even with a clean digital RF source.
Shell
I very much enjoy your explanations Shell! Thanks for taking the time to post here, your experimental method is informative and understandable. Learning a lot from your posts, keep on doing great work!
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#3374
by
SeeShells
on 30 Jun, 2016 22:52
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It is a Betty Crocker RF mixer even with a clean digital RF source.
Shell
I very much enjoy your explanations Shell! Thanks for taking the time to post here, your experimental method is informative and understandable. Learning a lot from your posts, keep on doing great work!
Thanks, that means a lot.
Everyone knows that this is a very hot fringe topic for many reasons, but one that deserves a solid answer. I along with others DYIers (even non-DYIer EagleWorks) are trying to provide those answers, or at least a sliver of proof that this might be a real effect.
If it's not real then we have gained something and if it is real, it could be like discovering fire for humanity. Of course we all would love to set things on fire
but the truth in data will rule if it can fire up the world, or we start tearing apart our Betty Crocker Blenders for another cause.
My Very Best,
Shell
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#3375
by
Tellmeagain
on 30 Jun, 2016 22:53
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A question about simulated EM field in a frustum, any mode,
What is the strongest E field strength in the cavity when 900W power is ohmically absorbed by the walls? Will it exceed the air breakdown strength? Thanks
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#3376
by
SeeShells
on 01 Jul, 2016 00:04
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Yes there is enough power. It depends on the induced voltage differentials between the metal sections inside of the cavity. Bad solder joints, bad construction, sharp edges etc.
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#3377
by
Rodal
on 01 Jul, 2016 02:31
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A question about simulated EM field in a frustum, any mode,
What is the strongest E field strength in the cavity when 900W power is ohmically absorbed by the walls? Will it exceed the air breakdown strength? Thanks
Yes, it is possible for the E field to exceed the air breakdown strength.
And it is evident from rfmguy's picture that at the moment he can have no idea of what mode shape (if any) is being excited, based on this:
If my memory serves me right, when a FEKO model was made of his cavity, the nearest mode shape was an uncommon one that nobody else had reported testing before (not TM212, not TE012, not TE013)
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#3378
by
Bob Woods
on 01 Jul, 2016 02:36
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Everyone knows that this is a very hot fringe topic for many reasons, but one that deserves a solid answer.
There's no such thing as fringe science. I'd dare to say that all breakthroughs started on the fringe.
As Jerry Garcia and the boys said... Keep on Truckin'
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#3379
by
Rodal
on 01 Jul, 2016 02:54
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A question about simulated EM field in a frustum, any mode,
What is the strongest E field strength in the cavity when 900W power is ohmically absorbed by the walls? Will it exceed the air breakdown strength? Thanks
Yes, it is possible for the E field to exceed the air breakdown strength.
And it is evident from rfmguy's picture that at the moment he can have no idea of what mode shape (if any) is being excited, based on this:
If my memory serves me right, when a FEKO model was made of his cavity, the nearest mode shape was an uncommon one that nobody else had reported testing before (not TM212, not TE012, not TE013)
You're correct in the mode can't be determined from this thermal image, although you can see that the magnetron on the right side of the video heats up as much as the small endplate. If there wan't no internal resonance the magnetron would be seeing a very high VWSR show up as increased magnetron heating and the cavity would be cooler. This shows some energy is being transferred into the cavity, although what mode(s) are being excited we can't know from the video.
Shell
By stating
And it is evident from rfmguy's picture that at the moment he can have no idea of what mode shape (if any) is being excited, based on this:
I did
not mean
(if any mode shape at all)but I meant instead
(if any unique mode shape)because it is always difficult to excite higher mode shapes by themselves. It is not at all uncommon to have
mode participation where two (and sometimes three) adjacent mode shapes may participate together, particularly when the mode shapes are close in frequency to each other.
The VSWR would show resonance but from that one would not be able to know that there is juxtaposition of two modes participating together. Certain numerical simulations with COMSOL and Meep have shown such participation of mode shapes as well.
Many discussions of mode shapes in this thread discuss resonance without taking into account mode shape participation, which is something known to occur not only in electromagnetic modes but it is also very common in mechanical vibration.
When using a magnetron (as rfmwguy is doing)
the likelihood of such mode participation is much enhanced because magnetrons used in microwave ovens have a bandwidth and they exhibit frequency modulation and therefore it is not unlikely to excite more than one unique mode shape.
Juxtaposition, mode participation will make it more difficult to show a unique mode shape in an infrared video.
but the truth in data will rule if it can fire up the world, or we start tearing apart our Betty Crocker Blenders for another cause.