Author Topic: EM Drive Developments Thread 1  (Read 797256 times)

Offline JohnFornaro

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Re: EM Drive Developments
« Reply #2480 on: 10/23/2014 01:01 PM »
A much higher frequency...

...My impression is that the discrepancy...

An honest attempt at understanding, but still fundamentally a grasping of straws.
Sometimes I just flat out don't get it.

Offline JohnFornaro

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Re: EM Drive Developments
« Reply #2481 on: 10/23/2014 01:10 PM »
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.
Sometimes I just flat out don't get it.

Offline JohnFornaro

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Re: EM Drive Developments
« Reply #2482 on: 10/23/2014 01:12 PM »
Another device of equivalent preagmatic utility.
Sometimes I just flat out don't get it.

Offline Rodal

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Re: EM Drive Developments
« Reply #2483 on: 10/23/2014 01:31 PM »
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.
« Last Edit: 10/23/2014 03:41 PM by Rodal »

Offline Rodal

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Re: EM Drive Developments
« Reply #2484 on: 10/23/2014 01:36 PM »
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?

« Last Edit: 10/23/2014 03:01 PM by Rodal »

Offline birchoff

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Re: EM Drive Developments
« Reply #2485 on: 10/23/2014 01:43 PM »
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?

Offline Rodal

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Re: EM Drive Developments
« Reply #2486 on: 10/23/2014 01:55 PM »

Does this mean we have collectively gotten to the point that there is not enough information available to make any conclusions?
No:
Quote
The reports of my death have been greatly exaggerated.
Collective interested in finding out the reason for EMDrive's measured thrust
« Last Edit: 10/23/2014 01:55 PM by Rodal »

Offline JohnFornaro

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Re: EM Drive Developments
« Reply #2487 on: 10/23/2014 02:05 PM »
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?
« Last Edit: 10/23/2014 02:07 PM by JohnFornaro »
Sometimes I just flat out don't get it.

Offline JohnFornaro

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Re: EM Drive Developments
« Reply #2488 on: 10/23/2014 02:08 PM »

Does this mean we have collectively gotten to the point that there is not enough information available to make any conclusions?
No:
Quote
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.
Sometimes I just flat out don't get it.

Offline Rodal

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Re: EM Drive Developments
« Reply #2489 on: 10/23/2014 02:24 PM »

Does this mean we have collectively gotten to the point that there is not enough information available to make any conclusions?
No:
Quote
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. 

Quote
In the realm of ideas everything depends on enthusiasm... in the real world all rests on perseverance.
Johann Wolfgang von Goethe

« Last Edit: 10/23/2014 02:46 PM by Rodal »

Offline Rodal

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Re: EM Drive Developments
« Reply #2490 on: 10/23/2014 03:11 PM »
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.
« Last Edit: 10/23/2014 03:34 PM by Rodal »

Offline Notsosureofit

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Re: EM Drive Developments
« Reply #2491 on: 10/23/2014 03:38 PM »
Of course the original comment was to address the time delay.

Offline JohnFornaro

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Re: EM Drive Developments
« Reply #2492 on: 10/23/2014 03:57 PM »
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.
Sometimes I just flat out don't get it.

Offline Notsosureofit

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Re: EM Drive Developments
« Reply #2493 on: 10/23/2014 04:18 PM »
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.

Offline Rodal

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Re: EM Drive Developments
« Reply #2494 on: 10/23/2014 04:42 PM »
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 d2xdt2 + 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=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 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.
« Last Edit: 10/23/2014 05:10 PM by Rodal »

Offline zen-in

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Re: EM Drive Developments
« Reply #2495 on: 10/23/2014 05:11 PM »
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.
« Last Edit: 10/23/2014 05:17 PM by zen-in »

Offline Rodal

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Re: EM Drive Developments
« Reply #2496 on: 10/23/2014 05:24 PM »
...
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.
« Last Edit: 10/23/2014 06:16 PM by Rodal »

Offline Notsosureofit

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Re: EM Drive Developments
« Reply #2497 on: 10/23/2014 05:34 PM »
Not to forget the energy stored in the spring. (the plots record displacement)
« Last Edit: 10/23/2014 05:36 PM by Notsosureofit »

Offline aero

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Re: EM Drive Developments
« Reply #2498 on: 10/23/2014 05:41 PM »
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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Offline JohnFornaro

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Re: EM Drive Developments
« Reply #2499 on: 10/23/2014 06:00 PM »
 
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.

Quote from: Rodal
...throwing the baby with the bathwater...

Plus, , Miz Scarlet.
Sometimes I just flat out don't get it.

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