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#2480
by
JohnFornaro
on 23 Oct, 2014 13:01
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A much higher frequency...
...My impression is that the discrepancy...
An honest attempt at understanding, but still fundamentally a grasping of straws.
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#2481
by
JohnFornaro
on 23 Oct, 2014 13:10
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The dimensions I suggested on A1.4 are inaccurate, because the support is behind the device. The proportions of the device are correct.
The actual dimensions of the device are roughly presented and are not off by more than a few single digit percentages, since the support is not all that far away from the center of the device.
The only way to test the theory of resonance mentioned earlier, is to analyze these proportions with the reported frequencies, and see if a resonant mode is reached.
This search is beyond my present capabilities, and not at all in my to-do list.
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#2482
by
JohnFornaro
on 23 Oct, 2014 13:12
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Another device of equivalent preagmatic utility.
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#2483
by
Rodal
on 23 Oct, 2014 13:31
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It is incorrect to state that only DC fields can produced ionic winds. I don't know whether such misunderstanding comes from getting information from Wikipedia.
AC fields can also produce ionic wind in a variety of ways. For example, the point electrode and ring electrode system is capable of generating electric winds (with velocities of few m/s) for both DC and AC applied voltages. In the AC regime, ions generated within the corona move in the field and migrate a distance before recombining; the net flow of ions away from the corona creates a time-averaged force that drives the steady flows. AC coronas can sustain wind velocities of over 1m/s independent of electrode separation in marked contrast to DC coronas.
Another arrangement in which AC fields can produce ionic wind is dielectric barrier discharge actuators. AC applied across the electrodes through the dielectric produces a variety of electric breakdown phenomena (e.g., corona, streamers, and plasma). Spark breakdown is prevented by the dielectric barrier. The dielectric material needs to be in contact with electrodes such that the electrodes contact each surface of the dielectric.
Transient migration of charged species within AC fields also gives rise to steady electric winds.
In contrast to winds driven by DC fields, AC fields (as in the point electrode and ring electrode system ) generate wind velocities comparable with (or better than) the strongest DC winds for any value of the electrode separation. In the high-frequency AC regime (>1 KHz), the electric force is localized within a region near the tip of the point electrode.
From a fundamental perspective, any type of electric wind (DC or AC) derives from the same basic mechanism whereby a steady flux of ions transfers momentum to the surrounding fluid to drive steady gas flows.
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#2484
by
Rodal
on 23 Oct, 2014 13:36
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Another device of equivalent preagmatic utility.
Doesn't the pictured device only work in a partial vacuum (thus the glass enclosure) and neither
the discussed NASA Eagleworks, Shawyer or Chinese experiments were conducted in such partial vacuum conditions inside glass enclosures?
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#2485
by
birchoff
on 23 Oct, 2014 13:43
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I ... estimate ... the Flight thruster dimensions ...
w-small = 1"
w-big = 2"
height = 3"
...
I am dizzy with all the tests that Shawyer has conducted and with the different names he gives the tested device. ...
This is circumstantial and corroborating evidence supporting the conjecture regarding the intentional reluctance of the experimentors to freely share their data.
The reluctance is certainly understandable, for at least three reasons, none of which can be discussed except on an informal basis among disinterested professional friends:
1. A surfeit of professional pride in understanding the obscure physics, combined with the typical disregard paid by professionals to amateur website contributors.
B. A pragmatic need to share without sharing, knowing full well the economic benefits of a vastly superior propulsive method.
iii. A stubborn refusal to realize that nothing is being seen.
Vee. Other reasons, such as keeping the rabble occupied with measuring Faztek thingies, so as to keep them off the streets protesting the forty year lack of accomplishment at NASA at doing what was promised back then; a peaceful future realizing mankind's destiny in the universe at large.
As I mentioned at:
http://forum.nasaspaceflight.com/index.php?topic=29276.msg1274449#msg1274449
I note that we are spending a lotta time arguing about these dimensions. The good Doctor asked, rather politely, a hundred or more pages ago, but got only partial dimensional answers. Since then Paul March decided to go mum.
Easily answered questions go without answer, which reflects on those who experiment, not on those who try to understand.
I'd like to thank the EagleWorks team for their help and cooperation. (They should probably set up shop in Awizona; 'twould help their worldview.)
On the plus side, thanks to decent forum moderation, we no longer have to hear from those who disparage everybody's credentials.
Does this mean we have collectively gotten to the point that there is not enough information available to make any conclusions?
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#2486
by
Rodal
on 23 Oct, 2014 13:55
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Does this mean we have collectively gotten to the point that there is not enough information available to make any conclusions?
No:
The reports of my death have been greatly exaggerated.
Collective interested in finding out the reason for EMDrive's measured thrust
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#2487
by
JohnFornaro
on 23 Oct, 2014 14:05
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I ... estimate ... the Flight thruster dimensions ...
w-small = 1"
w-big = 2"
height = 3"
...
I am dizzy with all the tests that Shawyer has conducted and with the different names he gives the tested device. ...
Does this mean we have collectively gotten to the point that there is not enough information available to make any conclusions?
Yes, unequivocally.
Tried have you, young Paduan. Now, looook harder must you, if to find a new force you seek.
I've been following that work since '09, and the reported effects continue to verge on noise, lack repeatability, are not supported by a fuller disclosure, and are largely ignored by paid and tenured faculty. Each successive experiment claims a subtly different operating principle; still, the trendline for results is flat at best, and not pragmatically applicable at worst.
If you, Frob, Mull, NotSo, Zen, and who all else, believe that there is a line of inquiry which would support a theory of pushing against, for want of a better term, the ether, then maybe it's time for a new thread, laying out the hardware and protocol for a new experiment.
I offer to buy the five of you a Scotch, served by my mixologist, natch, the day after the device is truthfully floated across the conference room table.
Edit: Uhhhh.... the six of you. How could I have forgotten the good doctor?
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#2488
by
JohnFornaro
on 23 Oct, 2014 14:08
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Does this mean we have collectively gotten to the point that there is not enough information available to make any conclusions?
No:
The reports of my death have been greatly exaggerated.
Collective interested in finding out the reason for EMDrive's measured thrust
Disagree. Time to create theory, not attempt to understand that which is being kept under wraps.
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#2489
by
Rodal
on 23 Oct, 2014 14:24
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Does this mean we have collectively gotten to the point that there is not enough information available to make any conclusions?
No:
The reports of my death have been greatly exaggerated.
Collective interested in finding out the reason for EMDrive's measured thrust
Disagree. Time to create theory, not attempt to understand that which is being kept under wraps.
Well, there are still those of us here whose only purpose being in this thread was and still is to objectively understand the reason for EMDrives's measured thrust.
We are not here with an agenda to show that the results are an experimental artifact nor do we have an agenda to explain it using any particular exotic physics. Our only object has been and continue to be to understand the EMDrive's measured thrust and we think we have made very considerable progress in this regard. The level of discourse in this thread, including mathematical analysis, spreadsheets, numbers, AutoCAD drawings with dimensions, statistical analysis, C programs with tens of thousands of formulas explored, quantitative discussion of physics including photon rockets, dark matter, modified inertia, etc., is clearly the best that can be found in the Internet concerning discussion of the EM Drive.
We don't have any intention to go away at this point in time.
Thanks to all who have contributed to this thread by performing calculations, by critically examining theories, by providing different reports, presentations and information, by providing dimensions for drawings and also thanks to those who have provided humor along the way.
In the realm of ideas everything depends on enthusiasm... in the real world all rests on perseverance.
Johann Wolfgang von Goethe
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#2490
by
Rodal
on 23 Oct, 2014 15:11
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A much higher frequency might indicate flex in the arm itself.
Prima facie evidence that not all that much is happening.
Could you repeat that?
Concerning NotSoSureOfIt question regarding March perhaps not quoting the lowest
mechanical natural torsional frequency of the inverted pendulum, why would that be "Prima facie evidence that not all that much is happening" ?
Why would arm-bending-motion of 1.5"by1.5" Aluminum beams be evidence of "not all that much happening"?
If there would be bending of the arm, as posited by NotSoSureOfIt, what would excite such arm-bending-motion of 1.5"by1.5" Aluminum beams?
One reaches the opposite conclusion: that if there would be would arm-bending-motion of 1.5"by1.5" Aluminum beams, actually more would be happening than just rotational (torsional) motion of the torsion inverted pendulum.
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#2491
by
Notsosureofit
on 23 Oct, 2014 15:38
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Of course the original comment was to address the time delay.
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#2492
by
JohnFornaro
on 23 Oct, 2014 15:57
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A much higher frequency might indicate flex in the arm itself.
Prima facie evidence that not all that much is happening.
Could you repeat that?
Concerning NotSoSureOfIt question regarding March perhaps not quoting the lowest mechanical natural torsional frequency of the inverted pendulum, why would that be "Prima facie evidence that not all that much is happening" ?
Why would arm-bending-motion of 1.5"by1.5" Aluminum beams be evidence of "not all that much happening"?. ...
If there are micronewtons being "detected", and it is thought that somehow the vibrations associated with these forces are "flexing" the beam, surely the beam is not in danger of breaking. Not much flexing is happening, because not much force is being detected.
NotSo didn't say anything about March "not quoting" anything. To have done so would ascribe motive, and that is not the case. NotSo is saying and only saying that another explanation about the frequency might indicate that the arm itself is flexing.
Again, to me, there does not seem to be much "flexure" at all in the massive beam at hand. Massive in comparison to the "detected" forces.
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#2493
by
Notsosureofit
on 23 Oct, 2014 16:18
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There are microneutons of force moving lbs of mass against an unknown damped spring constant to equilibrate after an unknown distance in an unknown time.
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#2494
by
Rodal
on 23 Oct, 2014 16:42
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Of course the original comment was to address the time delay.
Prima facie evidence that not all that much is happening.
I attach the time response I computed for the nonlinear coupled equations of motion for the torsional inverted pendulum using
Mathematica, and the known parameters. I obtained the nonlinear coupled equations of motion computing the Lagrangian also using
Mathematica.
As it is evident from the graph the 2 sec time delay comes straight from the dynamics of the torsional inverted pendulum. The 2 sec time delay is certainly not a thermal effect, it is fully explained by classical inertia response. Any mechanical system with an equation of motion of the form m d
2xdt
2 + c dx/dt + k x = F(t) has a time-dependent response. (Where m, c and k are matrices of course, and where in this case we include the nonlinear coupling terms on the right hand side)
I have published articles in peer-reviewed journals concerning calculation of much more complicated response than this. See for example:
http://appliedmechanics.asmedigitalcollection.asme.org/article.aspx?articleid=1407189A simple calculation of the Fourier dimensionless time based on the known heat capacity, density and thermal conductivity for the materials involved, as well as characteristic dimension, readily shows that this 2 sec time delay cannot be due to thermal effects, as also intuited by Paul March (using other words) early on in this thread.
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#2495
by
zen-in
on 23 Oct, 2014 17:11
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There are microneutons of force moving lbs of mass against an unknown damped spring constant to equilibrate after an unknown distance in an unknown time.
I attach the time response I computed for the nonlinear coupled equations of motion for the torsional inverted pendulum using Mathematica, and the known parameters. I obtained the nonlinear coupled equations of motion computing the Lagrangian also using Mathematica.
As it is evident from the graph the 2 sec time delay comes straight from the dynamics of the torsional inverted pendulum. The 2 sec time delay is certainly not a thermal effect, it is fully explained by classical inertia response. Any mechanical system of the form m d2xdt2 + c dx/dt + k x = F(t) has a time-dependent response.
I have published articles in peer-reviewed journals as the Journal of Applied Mechanics concerning calculation of much more complicated response than this. See for example: http://appliedmechanics.asmedigitalcollection.asme.org/article.aspx?articleid=1407189
A simple calculation of the Fourier dimensionless time based on the known heat capacity, density and thermal conductivity for the materials involved, as well as characteristic dimensions, readily shows that this 2 sec time delay cannot be due to thermal effects, as also remarked by Paul March (using other words) early on in this thread.
No doubt there is an inertial component to the thrust step response. However its presence doesn't negate a thermal signature in the thrust step response. The graphs we have seen do not rule that out. If an exponential step response, due to a thermal effect, was convolved with the step response you derived it would show the exponential shape of Shawyer's and the JSC thrust plots.
It also doesn't explain why the thrust continues after the RF is turned off. The plots record thrust, not velocity. Inertia of the balance system and apparatus can explain continued velocity but not a continued force after the RF is switched off. The continued force seen in both Shawyer's and the JSC graphs indicate stored energy that is being released after the RF is switched off.
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#2496
by
Rodal
on 23 Oct, 2014 17:24
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...
No doubt there is an inertial component to the thrust step response. However its presence doesn't negate a thermal signature in the thrust step response. The graphs we have seen do not rule that out. If an exponential step response, due to a thermal effect, was convolved with the step response you derived it would show the exponential shape of Shawyer's and the JSC thrust plots.
It also doesn't explain why the thrust continues after the RF is turned off. The plots record thrust, not velocity. Inertia of the balance system and apparatus can explain continued velocity but not a continued force after the RF is switched off. The continued force seen in both Shawyer's and the JSC graphs indicate stored energy that is being released after the RF is switched off.
As we have already established earlier in this thread in discussions with Paul March, there is a (separate from the 2 sec delay) known issue (already discussed in the NASA Eagleworks report) of longer term drift of the baseline that Paul March attributed to interaction between the magnetic damper and the power cable as well as thermal effects from the unit they have at the back. Observe that
this longer term drift also has a damping/inertial component. The much longer "continued force seen" in Shawyer's demonstrator is much larger and time-delayed than the one at NASA Eagleworks.All these time delays cannot be juxtaposed together into one big messy ball to justify throwing the baby with the bathwater and to conclude this as "Prima facie evidence that not all that much is happening." Such a conclusion is negated by the evidence.
On the contrary: the evidence shows that something is happening at the NASA Eagleworks tests, in the 2 sec time delay pulse response that is not possible due to thermal effects. The initial impulsive response is what needs explanation.
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#2497
by
Notsosureofit
on 23 Oct, 2014 17:34
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Not to forget the energy stored in the spring. (the plots record displacement)
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#2498
by
aero
on 23 Oct, 2014 17:41
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I am concerned about the ionic wind explanation. I have applied F = mdot*Ve for the thrust and calculated some candidate values for mdot and Ve for the known thrusters' test cases.
thrust air mass air volume velocity energy
kg-m/s, N kg liters m/s .5 mv^2
0.0000501 0.001 0.82 0.05 1.26E-06
0.0000554 0.001 0.82 0.06 1.53E-06
0.0000912 0.001 0.82 0.09 4.16E-06
0.016 0.100 81.63 0.16 1.28E-03
0.17 0.500 408.16 0.34 2.89E-02
0.214 0.500 408.16 0.43 4.58E-02
0.214 0.500 408.16 0.43 4.58E-02
0.315 0.500 408.16 0.63 9.92E-02
Of course these are just numbers from my hip pocket but its quite evident that the energy lost to ionic wind would not be detected.
For the Brady cases (first 3) the moving air volume and velocity would be overlooked if they were not watching for it.
Shawyer tested his experimental device within an enclosure to avoid artifacts from external air currents. Ionic wind would have been internal to his enclosure.
Shawyer tested his demonstrator on a cooled test stand. That would probably mask any ionic wind.
I don't know anything about the test setup for the flight model or about the Chinese test setup, as regards to detecting ionic wind.
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#2499
by
JohnFornaro
on 23 Oct, 2014 18:00
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All these time delays cannot be juxtaposed together into one big messy ball to ... conclude this as "Prima facie evidence that nothing is happening."
Nobody said that. I said only that there was prima facie evidence that
not all that much is happening.
I didn't say anything about "time delays" either, nor did I ascribe personal motive to NotSo's suggestion regarding time delays.
Please do not read beyond what I have written.
If there are barely detected oscillating micronewtons of force acting on the experimental apparatus, no doubt there is some oscillating flexural bending in the beam, a number that is probably of the same magnitude as the number of angels who can dance on a pin.
Their experiment does not fail solely because of this issue.
I quite understand that you seek to understand the reported results. Still, there is
not much happening.
...throwing the baby with the bathwater...
Plus,
, Miz Scarlet.