Author Topic: EM Drive Developments - related to space flight applications - Thread 3  (Read 1872338 times)

Offline Rodal

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...It leads to looking at issues regarding the air bearing for a starter. We used air bearings on much of the equipment we designed in the semiconductor industry We once designed a flat disk rotational bearing and had issues with it. Once it started to move it tended to want to continue moving and sometimes accelerating. We finally related it to the way the pressure waves were traveling between the plates creating a pattern that imparted movement to the top floating plate. We also saw the same effect in air bearing spindles used in dicing saws where the internal air bearing wasn't mated correctly and would lead to rotation in the spindle with out power being applied.

It was hard to think of a way we could test these theories as air is hard to see until one of my techs decided to simply put his hand in front of the air flow from the rotational bearing and said he could feel the differences in pressure. The body is sometimes a great detector.

This is why I intend as one test to float my device, it's close to being frictionless and only the viscosity of the water needs to be overcome to see movement. No weird air bearing issues.
 
This paper compares the air bearing with other methods to simulate weightlessness and concludes that the air bearing is the superior method:   http://www.space-electronics.com/Literature/SAWE_Papers/Spherical_Gas_Bearing_Weightlessness.pdf

I tried searching for air bearing problems , and disadvantages and I couldn't find much under acceleration problems. 

Your experience with this case is very valuable:

Quote from: SeeShells
  Once it started to move it tended to want to continue moving and sometimes accelerating. We finally related it to the way the pressure waves were traveling between the plates creating a pattern that imparted movement to the top floating plate

If this was going on with the Demonstrator test, it would be very difficult to tell what part of the response (if any) is real and what is an experimental artifact.
« Last Edit: 06/08/2015 03:51 PM by Rodal »

Offline Rodal

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We would need to know what method was used to balance the Demonstrator and what was the Center of Mass offset from the Center of Rotation in this test, the machining accuracy and the hydrodynamics of the air flow in the bearing.


There certainly appears to be an interaction with the power consumed by the EM Drive as when the power to the EM Drive is turned off, the acceleration rate decreases in conjunction with the time at which the power was turned off.




Quote
There are significant drawbacks with the use of
air bearings. One drawback is the existence of
gravitational torques. The center of mass of the
simulator must be extremely close to the center of
rotation of the bearing to minimize the gravitational
torque about the center of rotation. Moving the center
of mass toward the center of rotation is referred to as
'balancing' the table. The goal of balancing the
SSACS is to increase the period of oscillation as far as
possible without causing system instability.
...
The common procedure used to balance airbearing
satellite simulators is known as manual
balancing. This is a time-consuming, iterative process
where lead weights of varying mass are placed on the
simulator at various locations in an attempt to balance
the table. The process is finalized by carefully
adjusting several strategically placed set screws to
zero-in' the CM to the CR.
This manual method of balancing has advantages
and disadvantages. Manual balancing is relatively
simple to conceive and execute. It requires only
patience and a little skill in weight placement. On the
other hand, the amount of time required to balance the
SSACS is considerable, often several hours, and the
results can be disappointing. After considerable time
spent in the manual balancing process, the CM offset is
still large enough to create oscillations around the CR
with a period of approximately 20 seconds
« Last Edit: 06/09/2015 01:47 PM by Rodal »

Offline vulture4

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We now know that the vacuum field is in fact formally necessary for the stability of atoms in quantum theory.[/b] As we saw..., radiation reaction will cause canonical commutators [x, px] to decay to zero unless the fluctuating vacuum field is included, in which case commutators are consistently preserved."
Puthoff has a very clear way of explaining things, so does Milonni. I believe this will help most of the people here to understand this, without getting too deep into the Standard Model physics.
Puthoff provides clear explanations, but not necessarily accurate ones. The rigor of a science is measured not by its ability to explain, but by its ability to predict. Puthoff utilized a theory he called stochastic electrodynamics to treat particles as Newtonian bodies with some allowances for relativity and the addition of concepts of energy exchange with a surrounding field.

The difficulty is that these ideas have long since been superseded by quantum mechanics, which is why they aren't seen in current texts or used in current theories. An electron in ground state is not a canonical commutator. It might be more understandably described as a standing wave, or a probability density function.  It exists at a much lower energy state than a free electron, which can indeed radiate if accelerated. An electron in the ground state cannot radiate because there is no lower energy state to which it can decay.
« Last Edit: 06/08/2015 05:40 PM by vulture4 »

Offline ZuluMoon99

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"Thought the Lightsail could overcome the low-orbit forces and get moving outward...apparently not. "

FYI, this particular iteration and the next are to test sail deployment, very low orbit to ensure it operates as planned in weightlessness. Only on the third iteration [Due for launch in late 2016, I believe] will they try for changing orbital circumference.

Regards

Offline rfmwguy

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When it's turned off, all the energy has to be attenuated and the asymmetry and acceleration persists until all the energy is dissipated into thrust & heat.
If the thrust is proportional to the intensity of the microwave energy in the resonator, then the latter could be easily measured and compared to thrust. But IMO the microwave energy level would have dropped to an undetectable level in a very small fraction of a second after power was terminated. OTOH if the acceleration measurement is the result of a thermal heating effect and not reactionless propulsion, it might well have shown the persistance that was recorded.

My reading of Shawyer's original paper is that he asserts that radiation pressure will vary with the group velocity of the incident photons. However it is well established that the momentum of a photon is proportional only to its frequency, and SFAICT there are no reports to indicate that microwave frequency is shifted by a change in waveguide diameter.  So why would the radiation pressure on the two ends of the resonator be diferent?
https://en.wikipedia.org/wiki/Radiation_pressure#Radiation_pressure_by_particle_model:_photons

This has also interested me, a frequency transition not being due to shape, but what else can cause it? My experiment will only use copper as to not run the risk of intermodulation distortion (sum & difference frequencies) being created. http://en.wikipedia.org/wiki/Intermodulation

These unwanted signals are usually out of resonance in a transmission line or cavity, creating high standing waves, possible creating additional heating. Any ferromagnetic material, such as a nickle plating of a connector is another culprit for IMD.

Somewhere, I'd like to find a spectral display of Shawyer's frustum from the rf tap (sensor) he had on the frustum or a signal source and frustum spectrum comparison.
« Last Edit: 06/08/2015 05:12 PM by rfmwguy »

Offline jmossman

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(...)

QUESTION: what do others make of the velocity vs. power shown for this test (the only test performed with the EM Drive on an air bearing) ?

Does it make sense that "coasting period" with NO power can translate into continued acceleration (albeit at a slower rate of acceleration ?)

It looks to me after a brief period to charge the Q, as power is being attenuated, the frustum accelerates. As attenuation increases and power drops faster, the acceleration rises. When it's turned off, all the energy has to be attenuated and the asymmetry and acceleration persists until all the energy is dissipated into thrust & heat. Perfect IMO! (But I have not had my coffee yet.  :-\)
Todd

Seems like there are undisclosed variables/dynamics within Shawyer's setup.    :'(

My "kind" interpretation of t=210s to t=255s would be that the power supply and/or amplifier setup has some undisclosed time constants.  A less friendly interpretation would be to wonder if non-EM drive factors are contributing to the acceleration (such as the discussed air bearings).

The Shawyer graph arbitrarily starts at t=100s, and power applied between t=100s and t=125s corresponds to a period of velocity=0.  IMO, not enough information to confirm how much of the control/search/tracking algorithm is in play.  My back-of-napkin says the Q=60000 @ 2.4GHz charge/discharge time should be bounded by ~100 microseconds.  Only ~44.9999 seconds of uncertainty left to account for....   :P

Offline Rodal

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(...)

QUESTION: what do others make of the velocity vs. power shown for this test (the only test performed with the EM Drive on an air bearing) ?

Does it make sense that "coasting period" with NO power can translate into continued acceleration (albeit at a slower rate of acceleration ?)

It looks to me after a brief period to charge the Q, as power is being attenuated, the frustum accelerates. As attenuation increases and power drops faster, the acceleration rises. When it's turned off, all the energy has to be attenuated and the asymmetry and acceleration persists until all the energy is dissipated into thrust & heat. Perfect IMO! (But I have not had my coffee yet.  :-\)
Todd

Seems like there are undisclosed variables/dynamics within Shawyer's setup.    :'(

My "kind" interpretation of t=210s to t=255s would be that the power supply and/or amplifier setup has some undisclosed time constants.  A less friendly interpretation would be to wonder if non-EM drive factors are contributing to the acceleration (such as the discussed air bearings).

The Shawyer graph arbitrarily starts at t=100s, and power applied between t=100s and t=125s corresponds to a period of velocity=0.  IMO, not enough information to confirm how much of the control/search/tracking algorithm is in play.  My back-of-napkin says the Q=60000 @ 2.4GHz charge/discharge time should be bounded by ~100 microseconds.  Only ~44.9999 seconds of uncertainty left to account for....   :P

Good point, neither the graph or the text clarify as to when was the power turned on (was it turned on at t=0 ? or at t=100s or at some time in-between ?) and why the graph starts at t=100s.

Offline SeeShells

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...It leads to looking at issues regarding the air bearing for a starter. We used air bearings on much of the equipment we designed in the semiconductor industry We once designed a flat disk rotational bearing and had issues with it. Once it started to move it tended to want to continue moving and sometimes accelerating. We finally related it to the way the pressure waves were traveling between the plates creating a pattern that imparted movement to the top floating plate. We also saw the same effect in air bearing spindles used in dicing saws where the internal air bearing wasn't mated correctly and would lead to rotation in the spindle with out power being applied.

It was hard to think of a way we could test these theories as air is hard to see until one of my techs decided to simply put his hand in front of the air flow from the rotational bearing and said he could feel the differences in pressure. The body is sometimes a great detector.

This is why I intend as one test to float my device, it's close to being frictionless and only the viscosity of the water needs to be overcome to see movement. No weird air bearing issues.
 
This paper compares the air bearing with other methods to simulate weightlessness and concludes that the air bearing is the superior method:   http://www.space-electronics.com/Literature/SAWE_Papers/Spherical_Gas_Bearing_Weightlessness.pdf

I tried searching for air bearing problems , and disadvantages and I couldn't find much under acceleration problems. 

Your experience with this case is very valuable:

Quote from: SeeShells
  Once it started to move it tended to want to continue moving and sometimes accelerating. We finally related it to the way the pressure waves were traveling between the plates creating a pattern that imparted movement to the top floating plate

If this was going on with the Demonstrator test, it would be very difficult to tell what part of the response (if any) is real and what is an experimental artifact.
Yes, It could be tough to determine what was happening.

It was a red flag because of the continued thrust even after the power was shut off. But... seeing other tests show thrust w/o air bearings I tend to put it on the maybe side if it indeed caused this. Simply I don't know what type of air bearing he used, size, or even the pressures. Did they build it, did they use one from an OEM?????

In the paper world of numbers air bearings are far superior providing a almost frictionless bearing surface. In the real world they can cause issues if not set up correctly, as jets become clogged and incorrect high/low pressures can cause stability problems. We would see it in repairs of equipment and even in new designs. 

I would also note it was stable at first without power and something introduced enough thrust to overcome the mass of the table/equipment and this could very well be the EMdrive. The artifact after power was shut off was the residual action of the air bearing.

Shell

Offline deltaMass

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Velocity = roughly constant from t=0 to t=2 sec, and it becomes roughly zero after 2 sec until power is turned off

Does it make sense that "coasting period" with NO power can translate into continued acceleration (albeit at a slower rate of acceleration ?)

It leads to looking at issues regarding the air bearing for a starter. We used air bearings on much of the equipment we designed in the semiconductor industry We once designed a flat disk rotational bearing and had issues with it. Once it started to move it tended to want to continue moving and sometimes accelerating. We finally related it to the way the pressure waves were traveling between the plates creating a pattern that imparted movement to the top floating plate. We also saw the same effect in air bearing spindles used in dicing saws where the internal air bearing wasn't mated correctly and would lead to rotation in the spindle with out power being applied.

It was hard to think of a way we could test these theories as air is hard to see until one of my techs decided to simply put his hand in front of the air flow from the rotational bearing and said he could feel the differences in pressure. The body is sometimes a great detector.

This is why I intend as one test to float my device, it's close to being frictionless and only the viscosity of the water needs to be overcome to see movement. No weird air bearing issues.
 
Excellent points all and based on hard experience. It's also my view. Air bearings are notoriously finnicky and can produce spurious dynamic effects with just a little perturbation. For that reason I take these experimental results of Shawyer with a huge pinch of salt. I certainly wouldn't even begin to try and evince any physics from them.
« Last Edit: 06/08/2015 05:31 PM by deltaMass »

Offline rfmwguy

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Velocity = roughly constant from t=0 to t=2 sec, and it becomes roughly zero after 2 sec until power is turned off

Does it make sense that "coasting period" with NO power can translate into continued acceleration (albeit at a slower rate of acceleration ?)

It leads to looking at issues regarding the air bearing for a starter. We used air bearings on much of the equipment we designed in the semiconductor industry We once designed a flat disk rotational bearing and had issues with it. Once it started to move it tended to want to continue moving and sometimes accelerating. We finally related it to the way the pressure waves were traveling between the plates creating a pattern that imparted movement to the top floating plate. We also saw the same effect in air bearing spindles used in dicing saws where the internal air bearing wasn't mated correctly and would lead to rotation in the spindle with out power being applied.

It was hard to think of a way we could test these theories as air is hard to see until one of my techs decided to simply put his hand in front of the air flow from the rotational bearing and said he could feel the differences in pressure. The body is sometimes a great detector.

This is why I intend as one test to float my device, it's close to being frictionless and only the viscosity of the water needs to be overcome to see movement. No weird air bearing issues.
 
Excellent points all and based on hard experience. It's also my view. Air bearings are notoriously finnicky and can produce spurious dynamic effects with just a little perturbation. For that reason I take these experimental results of Shawyer with a huge pinch of salt. I certainly wouldn't even begin to try and evince any physics from them.

All good points. Perhaps the system had velocity at T=0 and the power-on condition temporarily halted it. Too much chart snipping in the time domain IYAM. He left himself wide open for critique.

Offline vulture4

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It's my understanding that the goalis to measure force. Was there some reason for not using a spring mounting and just measuring displacement?
« Last Edit: 06/08/2015 05:43 PM by vulture4 »

Offline deltaMass

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Re. the recent flyby reference to the Aachen group's Baby EmDrive and CubeSats, I'm reminded that their team leader has already flown a couple of amateur space missions with an outfit called PoqetQub (from memory).

This is a NASA forum, so presumably packed to the brim with orbital mechanics specialists!! So... what value of k (N/W) is needed to get EmDrive up from LEO, O Experts?

ETA: On reflection that's a dumb question  :-[
Any positive k value will do.
« Last Edit: 06/08/2015 05:47 PM by deltaMass »

Offline Rodal

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It's my understanding that the goalis to measure force. Was there some reason for not using a spring mounting and just measuring displacement?

Shawyer first tested it in a balance:

Quote
The engine was tested in a large static test rig
employing a calibrated composite balance to
measure thrust in both vertical and horizontal
directions. A total of 134 test runs were carried
out over the full performance envelope.
Fig 7 gives test results for 3 Vertical Thrust
test runs under the same input and tuner
conditions but for thrust vectors in the Up,
Down and Horizontal directions. This clearly
illustrates the loss of measured weight for the
Up vector, the increase in measured weight for
the Down vector, and a mean weight change
close to zero, for the horizontal vector. These
early comparative tests yielded specific thrusts
around 80mN/kW.

Notice that in the static test he also gets some force reading after power is off.

Engine in horizontal position still gives some thrust force reading
« Last Edit: 06/08/2015 05:51 PM by Rodal »

Offline WarpTech

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...
It is a perplexing problem and obviously not a realistic one, once you consider the power source is external and mass will increase indefinitely.

I wish you nothing but success in refining your theory into something wonderful. You have my respect for the attempt! But I cannot say in all honesty that your theory in its current form commands my respect. I'm pleased you see the criticisms for what they are intended to be. No hard feelings, I hope.

Here is what I've come up with for an expression where the force goes to zero and velocity is limited. See attached image. Keep in mind, in this context of GR, the coordinate speed of light is a variable, not a constant. So the speed limit shown here is a variable, that varies depending on the inertia content, inversely proportional to wavelength.

Comments?

Todd  PS: The photo does not appear rotated on my phone or computer, only here.

« Last Edit: 06/08/2015 05:49 PM by WarpTech »

Offline deltaMass

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My comment is that dv/dt = 0 for a photon

Offline WarpTech

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My comment is that dv/dt = 0 for a photon

It's not a photon, it's a Dirac particle. dv/dt is the acceleration of the group velocity of the particle.

Offline SeeShells

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Velocity = roughly constant from t=0 to t=2 sec, and it becomes roughly zero after 2 sec until power is turned off

All good points. Perhaps the system had velocity at T=0 and the power-on condition temporarily halted it. Too much chart snipping in the time domain IYAM. He left himself wide open for critique.

I would have done the test differently. Instead of putting all the weight onto a air bearing I would have suspended from the ceiling from the center point of the test jig. As even a small air bearing would have provided enough air bearing surface and balancing it out. Eliminate a lot of potential errors.

Offline Fugudaddy

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Is this relevant?
Human version:http://motherboard.vice.com/read/physicists-carve-logrithmic-spirals-into-steel-with-laser-vortexes?trk_source=recommended
Science version: https://www.osapublishing.org/oe/abstract.cfm?uri=oe-23-10-12562

This part seemed relevant to the current conversation:
Quote
We show clearly also how the Orbital Angular Momentum(OAM) associated with a helical wavefront induces rotation of vector fields along the optic axis of a focusing lens and confirmed by the observed surface micro-structures
.

and this:
Quote
These results highlight the complexity of the focal electric fields and the remarkable effect of the presence of a vortex phase on the vector beams which leads to rotation of the vector fields around the focal plane and inversion of the spiral direction, which was quite unexpected.


This lead to a link to this:
http://arxiv.org/ftp/arxiv/papers/1108/1108.5722.pdf

which was related, but don't know if it's been brought up before in the forums.
« Last Edit: 06/08/2015 06:30 PM by Fugudaddy »

Offline deltaMass

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{list type=lower-greek}l m n{/list}

That doesn't work with square brackets.
But I saw a post by A. N. Swallow (because of the god-awful search here I cannot locate his posts) which used Greek "mu".

So how do I shoehorn Greek into posts here?
« Last Edit: 06/08/2015 06:34 PM by deltaMass »

Offline deltaMass

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My comment is that dv/dt = 0 for a photon

It's not a photon, it's a Dirac particle. dv/dt is the acceleration of the group velocity of the particle.
Be careful to formulate your variable mass piece correctly:
http://en.wikipedia.org/wiki/Momentum#Objects_of_variable_mass
Note the correct vs. incorrect forms. It's a matter of using the correct frames

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