Author Topic: EM Drive Developments - related to space flight applications - Thread 3  (Read 1801988 times)

Offline nilabrk

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BTW The entire bread crumb thing makes me cringe.

So many times I've seen the case of a deluded researcher giving hints that, in retrospect, say: 'I don't know the answer, but I'm going to drop my hunches as if I know, and then take the credit when you find something interesting.' That's really been the trend in any kind of bogus technology guru situation. 

No offense to The Traveler -- just a heads up that the breadcrumb thing is a trope of rag-trade paperbacks and soap operas to get you to stick around after the ad-break/chapter. But good luck if you are able to get a head start before his peer reviewed paper comes out (that's a thing right? Aside from EW's forthcoming publication?). I think, with Shawyer at least, a good dollop of blind faith is required to remain satisfied.  :-\

Offline TheTraveller

In Shawyers Flight Thruster test the reported max thrust achieved was around 170mN.
...
That is approx 17 gf. Is a bit over the weight of 2 x US dollar coins. If I put them in your outstretched palm, could you feel the weight? Sure it is not a kg but the level is significant and not what some mosquito produces when it lands on your arm.

Traveller, do you know how Shawyer actually measured thrust, because according to his EmDriveForceMeasurement.pdf and due to his strange interpretation of action and reaction, he believes that direct measurement of the thrust from a non-accelerating EmDrive is impossible, and the test rigs discussed here, including Iulian's balance, should not measure any thrust at all.
Quote from: Pg. 2
The most important point to be made, is that to measure force, the cavity must experience acceleration. In a fully restrained cavity, thrust and reaction force cancel out. ...

Clearly, in a static situation, where T and R both exist as forces, they will cancel out. Thus any attempt to measure them by simply placing the thruster vertically on a set of scales will fail. If however the thrust is sufficient such that a = -g, then the thruster could be made to hover above the scales. ...

In free space, the thruster will simply accelerate at a m/s/s, and R will not be measurable. To measure R it is necessary to restrain the thruster against a fixed reference point.

However at rest, no force can be measured as R will cancel out T as in Fig 1. ...
and most importantly
Quote from: Pg. 3
A number of methods have been used in the UK, the US and China to measure the forces produced by an EmDrive thruster. In each successful case, the EmDrive force data has been superimposed on an increasing or decreasing background force, generated by the test equipment itself.

Indeed, in the UK when the background force changes were eliminated, in an effort to improve force measurement resolution, no EmDrive force was measured. This was clearly a result of attempting to measure the forces on a fully static thruster, where T and R cancel each other.

Does that mean that Shaywer's device includes actuators which accelerate the drive, and the measured thrust is extracted from the signal by subtracting the expected contribution of those actuators?

~Kirk

Not at my laptop. I have images of each case below.

He has placed them directly on scales, hung them from springs above scales, used balance beams with scales, plus he used a rotary air bearing system to show true acceleration.

Seems his preferred method is to work either against gravity (small end pushing up) or with gravity (small end pushing down).
"As for me, I am tormented with an everlasting itch for things remote. I love to sail forbidden seas.”
Herman Melville, Moby Dick

Online kdhilliard

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In Shawyers Flight Thruster test the reported max thrust achieved was around 170mN.
...
That is approx 17 gf. Is a bit over the weight of 2 x US dollar coins. If I put them in your outstretched palm, could you feel the weight? Sure it is not a kg but the level is significant and not what some mosquito produces when it lands on your arm.

Traveller, do you know how Shawyer actually measured thrust, because according to his EmDriveForceMeasurement.pdf and due to his strange interpretation of action and reaction, he believes that direct measurement of the thrust from a non-accelerating EmDrive is impossible, and the test rigs discussed here, including Iulian's balance, should not measure any thrust at all.
Quote from: Pg. 2
The most important point to be made, is that to measure force, the cavity must experience acceleration. In a fully restrained cavity, thrust and reaction force cancel out. ...

Clearly, in a static situation, where T and R both exist as forces, they will cancel out. Thus any attempt to measure them by simply placing the thruster vertically on a set of scales will fail. If however the thrust is sufficient such that a = -g, then the thruster could be made to hover above the scales. ...

In free space, the thruster will simply accelerate at a m/s/s, and R will not be measurable. To measure R it is necessary to restrain the thruster against a fixed reference point.

However at rest, no force can be measured as R will cancel out T as in Fig 1. ...
and most importantly
Quote from: Pg. 3
A number of methods have been used in the UK, the US and China to measure the forces produced by an EmDrive thruster. In each successful case, the EmDrive force data has been superimposed on an increasing or decreasing background force, generated by the test equipment itself.

Indeed, in the UK when the background force changes were eliminated, in an effort to improve force measurement resolution, no EmDrive force was measured. This was clearly a result of attempting to measure the forces on a fully static thruster, where T and R cancel each other.

Does that mean that Shaywer's device includes actuators which accelerate the drive, and the measured thrust is extracted from the signal by subtracting the expected contribution of those actuators?

Not at my laptop. I have images of each case below.

He has placed them directly on scales, hung them from springs above scales, used balance beams with scales, plus he used a rotary air bearing system to show true acceleration.

Seems his preferred method is to work either against gravity (small end pushing up) or with gravity (small end pushing down).

Interesting.  Do you then agree that his EmDriveForceMeasurement.pdf suggests that with such methods no EmDrive force would be measured?

~Kirk

P.S. On a personal note, I hope you know that no one here is calling on you to defend Shawyer's position.  You just seem to be the one most familiar with his work.  I find his treatment of action-reaction to be very confusing, and I'd appreciate any breadcrumbs I get from you which would help explain just what he is thinking.

Online Rodal

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...

I think it speaks for itself how much attention the scientific and engineering community are paying to this work. There certainly won't be any increase thrust, as any such thrust was due to thermal or electronic noise in the first place. The experimental method is botched, and the data is incomprehensible (the error bars are far too large to make any justifiable conclusions). Also, none of it has even been peer-reviewed and the researchers don't seem to be interested in repeatability or having other researchers take a much deeper look at their work. The fact that my previous post was "widely reported" and deleted just shows how incredibly sensitive they and their supporters are to any criticism.
Factual correction:  Prof. Yang's papers (on her theoretical analysis and experimental measurements of the EM Drive) have been published in the peer-reviewed journal Acta Physica Sinica -Chinese Edition- (ACTA PHYS SIN-CH ED)
« Last Edit: 05/27/2015 12:08 AM by Rodal »

Offline TheTraveller

BTW The entire bread crumb thing makes me cringe.

So many times I've seen the case of a deluded researcher giving hints that, in retrospect, say: 'I don't know the answer, but I'm going to drop my hunches as if I know, and then take the credit when you find something interesting.' That's really been the trend in any kind of bogus technology guru situation. 

No offense to The Traveler -- just a heads up that the breadcrumb thing is a trope of rag-trade paperbacks and soap operas to get you to stick around after the ad-break/chapter. But good luck if you are able to get a head start before his peer reviewed paper comes out (that's a thing right? Aside from EW's forthcoming publication?). I think, with Shawyer at least, a good dollop of blind faith is required to remain satisfied.  :-\

With respect. Your opinion. Not mine.

Shawyer is under no obligation to help replication like me. He has clients that have entered into commercial arrangements with SPR & he needs to respect those contracts and the licensed IP.

I have information I can't disclose, yet, and not from Shawyer directly, that has removed any last little bit of doubt I had the thrust is very real. However like any new tech, still in development, there are issues that can cloud performance. As I was told my one replication, keeping a high Q frustum working at optimal Rf frequency is NOT easy. Smallest drift off and thrust stops. Constantly changing temp of various frustum areas also changes cavity frequency enough to detune. Cavity Q of 50,000 to 60,000 sounds great to get good thrust but it turns into a monster intent on NOT producing thrust.

Based on what I have learned, blasting away with a wide band magnetron into a low Q cavity may be a good option as it really reduces lost/NO thrust from being constantly off resonance with a high Q cavity.

I'm told the peer reviewed paper Shawyer will present in 2015,  with his commercial partners, will be an eye opened. No more doubts. All over. Time to start building or buying as the case may be EM Drives.
« Last Edit: 05/27/2015 12:27 AM by TheTraveller »
"As for me, I am tormented with an everlasting itch for things remote. I love to sail forbidden seas.”
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Offline WarpTech

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...

Therefore, any propellant-less propulsion device, must have some means of becoming depolarized. In the case of the frustum, stored energy is lost to heat as well as thrust, and this eventually depolarizes it so it can be re-charged and thrust again. Once again, it can only work in a pulsed mode, when power is ramping up and down quickly.

Todd
What do people think of the idea of driving the EM Drive with a TEmnp mode (transverse electric mode) such that the axial field is magnetic along the longitudinal direction.

This would be a solenoid, aka transformer primary or coupled inductor oriented axially with the frustum. It is a straightforward design I have been considering...

Quote
Then the idea would be to make the EM Drive more of a "one-way" street (1-way directional waves rather than a 2-way street with standing waves) by placing tiny ferrite beads (magnets) along so as to minimize reflections (as done in the solid state ruby maser).

The number and size of the ferrite beads would control the fine tradeoff between Q resonance (needed for reverberation) and directionality (needed for thrust).

How? Any magnetic material along the axis will transfer momentum forward to the frustum, but only at the expense of recoiling momentum toward the rear. If they are physical attached to one another, the result should be nil.

Quote

Perhaps this would allow the use of a cylindrical waveguide (instead of a truncated cone), one could control the amount of reflections by the size and number of ferrite beads along the axis.  (The size of the ferrite bead could be functionally graded such that the size of ferrite would monotonically increase in one direction, for example).

Also the use of a solid state material (such as the ruby used in the ruby maser) that can emit in a very wide range of microwave frequencies may allow much higher power to thrust force conversion.

Please notice as per the history of the Ruby Maser chart, that many Ruby Masers operated at similar microwave frequencies (2.4 GHz) as used for magnetrons for home cooking microwave ovens:

It's still beyond my comprehension at the moment. I'll give it some thought and do some research.

Todd

Online Rodal

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...

Therefore, any propellant-less propulsion device, must have some means of becoming depolarized. In the case of the frustum, stored energy is lost to heat as well as thrust, and this eventually depolarizes it so it can be re-charged and thrust again. Once again, it can only work in a pulsed mode, when power is ramping up and down quickly.

Todd
What do people think of the idea of driving the EM Drive with a TEmnp mode (transverse electric mode) such that the axial field is magnetic along the longitudinal direction.

This would be a solenoid, aka transformer primary or coupled inductor oriented axially with the frustum. It is a straightforward design I have been considering...

Quote
Then the idea would be to make the EM Drive more of a "one-way" street (1-way directional waves rather than a 2-way street with standing waves) by placing tiny ferrite beads (magnets) along so as to minimize reflections (as done in the solid state ruby maser).

The number and size of the ferrite beads would control the fine tradeoff between Q resonance (needed for reverberation) and directionality (needed for thrust).

How? Any magnetic material along the axis will transfer momentum forward to the frustum, but only at the expense of recoiling momentum toward the rear. If they are physical attached to one another, the result should be nil.

Quote

Perhaps this would allow the use of a cylindrical waveguide (instead of a truncated cone), one could control the amount of reflections by the size and number of ferrite beads along the axis.  (The size of the ferrite bead could be functionally graded such that the size of ferrite would monotonically increase in one direction, for example).

Also the use of a solid state material (such as the ruby used in the ruby maser) that can emit in a very wide range of microwave frequencies may allow much higher power to thrust force conversion.

Please notice as per the history of the Ruby Maser chart, that many Ruby Masers operated at similar microwave frequencies (2.4 GHz) as used for magnetrons for home cooking microwave ovens:

It's still beyond my comprehension at the moment. I'll give it some thought and do some research.

Todd

Dissipation in masers is produced by

1) the resistance of the copper structure,  (all EM Drives use this)
2) dielectric material loss  (NASA uses this)
3) ferrite magnetic permeability(apparently nobody has tried this, although Aquino suggested it)

You agree that attenuation (hence dissipation) gradient is responsible for the thrust in an EM Drive.

The EM Drive at NASA uses dielectric inserts (HDPE) which are most effective in TM transverse magnetic modes because they have an electric field in the axial direction (NASA is using mode TM212)

If you look at the numerical value of the relative magnetic permeability of ferrites you will see that probably we can accomplish much more by using ferrite inserts in TE modes (that have an axial magnetic field) than what we can accomplish with dielectric inserts in TM modes (that have an electric field in the axial direction) using their relative electric permittivity (look at their numerical value ~2).

We discussed much earlier in the thread having a single ferrite at one end (one of the end plates) in TE modes, just like NASA uses a single dielectric HDPE polymer insert in mode TM modes.  (See the paper by Aquino "How the Thrust of Shawyer’s Thruster can be Strongly Increased" ( https://hal.archives-ouvertes.fr/hal-01074608/document) and my comment here: http://forum.nasaspaceflight.com/index.php?topic=36313.msg1328595#msg1328595 )

We could have a functionally graded distribution of small dielectric inserts or small  ferrite inserts with ruby in between them, as in a maser.  The inserts should not occupy the whole cross section but just a small portion of it (in masers the ferrite beads are very small, placed at the combs).

The size of the dielectric (for TM modes) or the ferrite (TE modes) would monotonically increase from one end to the other (when using several inserts).

But, if you cannot meet me (perhaps yet) at the concept of a gradient of small ferrites distributed in the axial direction, can you please consider at least one ferrite insert at one end (as proposed by Aquino) ?

How about one ruby ?

http://deepblue.lib.umich.edu/bitstream/handle/2027.42/70658/JAPIAU-30-7-1061-1.pdf?sequence=2
« Last Edit: 05/27/2015 01:45 AM by Rodal »

Offline TheTraveller

Quote from: kdhilliard

Interesting.  Do you then agree that his EmDriveForceMeasurement.pdf suggests that with such methods no EmDrive force would be measured?

~Kirk

P.S. On a personal note, I hope you know that no one here is calling on you to defend Shawyer's position.  You just seem to be the one most familiar with his work.  I find his treatment of action-reaction to be very confusing, and I'd appreciate any breadcrumbs I get from you which would help explain just what he is thinking.

To be free to move or not is a relative term. How much movement is free to move? Bolt it to a satellite and it will not move relative to the satellite. Sit it on a scale and it can press down, move a micron and generate a force.

Sometime Roger Shawyer is not the best of technical writers and you need to do a bit of head scratching to understand his point of view.

I have no issues with the measurement paper and using scales to measure the force as the EM Drive does move on a scale, even if you can't see it.
« Last Edit: 05/27/2015 12:29 AM by TheTraveller »
"As for me, I am tormented with an everlasting itch for things remote. I love to sail forbidden seas.”
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Offline WarpTech

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(...)
It is not a closed system violating CoM, it is an open-system, separating forward and reverse propagating electromagnetic momentum by frequency, with the dispersive cavity then selectively dissipating and radiating the sorted momentum as heat.

As, I know, this has been espoused by some here prior. I'm just kind of slow on the uptake.

So why would a Peltier cooler generate thrust? An electric current drags high-frequency (hot) phonons from one end and leaving low-frequency (cold) phonons on the other. Kind of the same thing, in another media and operating regime. Or something like that.

I googled "Peltier Thrust" and found this:
http://www.theavalonfoundation.org/docs/peltier.html

Hal Puthoff mentioned. Usual suspect?

So, pending more evidence, at this time I'm persuaded this is a thermodynamic rather than a qv warping/compressing phenomena. I change my mind often about this stuff over the last couple weeks. If true, it precludes some exciting and energetic plasma applications.

Well put! The Peltier Thruster (PT) is a prime example of what I was talking about in another post. That any power to acceleration transducer can also be used to the opposite effect, but once it becomes polarized it's useless. In the case of the PT, once it reaches its ultimate thermal differential, there is no more thrust.

I was thinking along the same lines actually. Maxwell's demon, putting more energetic particles forward and slower ones backwards. That's what the Peltier effect does, but you must input power to do it. Thrust exponentially decays as temperature difference stabilizes. It makes sense to me anyway.


Offline Notsosureofit

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Just an FYI putting the power gain stage into the cavity itself as an oscillator..  Greatly simplifies the circuitry and operation.  Been there, successfully done that.  But, it's not the best method if you are trying to take precision measurements against a external frequency standard.  (found that out right away)

This is all I can find that is similar to what we would make as kids  (my uncle had a lathe in his basement)

http://www.google.st/patents/US2797324

I would hope for something solid state w/ more power than a diode to be available by now.

OK, done w/ the rant...
« Last Edit: 05/27/2015 01:21 AM by Notsosureofit »

Online Rodal

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Quote from: kdhilliard

Interesting.  Do you then agree that his EmDriveForceMeasurement.pdf suggests that with such methods no EmDrive force would be measured?

~Kirk

P.S. On a personal note, I hope you know that no one here is calling on you to defend Shawyer's position.  You just seem to be the one most familiar with his work.  I find his treatment of action-reaction to be very confusing, and I'd appreciate any breadcrumbs I get from you which would help explain just what he is thinking.

To be free to move or not is a relative term. How much movement is free to move? Bolt it to a satellite and it will not move relative to the satellite. Sit it on a scale and it can press down, move a micron and generate a force.

Sometime Roger Shawyer is not the best of technical writers and you need to do a bit of head scratching to understand his point of view.

I have no issues with the measurement paper and using scales to measure the force as the EM Drive does move on a scale, even if you can't see it.

<<To be free to move or not is a relative term. How much movement is free to move? >>

Fortunately we have the field of Mechanics that has answered this question.

displacement = (Force/ModulusOfElasticity)*( Length/CrossSectionalArea)

so, given an arbitrary Force, and any arbitrary geometrical dimensions, in order to have zero displacement you need to have a material with Infinite modulus of elasticity.

The answer is that there is no such Infinitely stiff material in our Universe.   ;)

So whoever asks for zero deformation, has to more rigorously define precisely what they mean by that.

« Last Edit: 05/27/2015 01:23 AM by Rodal »

Offline Notsosureofit

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That's why we always used a calibrated feedback force.

Online kdhilliard

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Quote from: kdhilliard

Do you then agree that his EmDriveForceMeasurement.pdf suggests that with such methods no EmDrive force would be measured?
To be free to move or not is a relative term. How much movement is free to move? Bolt it to a satellite and it will not move relative to the satellite. Sit it on a scale and it can press down, move a micron and generate a force.

Sometime Roger Shawyer is not the best of technical writers and you need to do a bit of head scratching to understand his point of view.

I have no issues with the measurement paper and using scales to measure the force as the EM Drive does move on a scale, even if you can't see it.
Fortunately we have the field of Mechanics that has answered this question.  ...

I absolutely agree that there cannot be any force measurement without some displacement, however small that displacement might be given the sensitivity of modern load cells, and I tried to interpret Shawyer's measurement paper that way, but his
Quote from: Pg. 3
A number of methods have been used in the UK, the US and China to measure the forces produced by an EmDrive thruster. In each successful case, the EmDrive force data has been superimposed on an increasing or decreasing background force, generated by the test equipment itself.

Indeed, in the UK when the background force changes were eliminated, in an effort to improve force measurement resolution, no EmDrive force was measured. This was clearly a result of attempting to measure the forces on a fully static thruster, where T and R cancel each other.
sure sounds like there must be more to his test rigs than meets the eye.

~Kirk

Offline ThinkerX

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Ok...the more pictures I see of Shawyer's 'Flight Thruster' the more it seems to me this is something he adapted, rather than built, at least for the shell.  To me, it looks like a reducer coupling, of the sort used to connect different diameters of pipe.  If memory serves, those are usually forged all in one piece.

So, for the DIY types, maybe check out the selection at a really big plumbing supply outfit?

Online Rodal

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« Last Edit: 05/27/2015 02:24 AM by Rodal »

Offline SeeShells

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String them together in your idea and add a ferrite bead. Looks good Dr. Rodal.

Offline WarpTech

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The answer is that there is no such Infinitely stiff material in our Universe.   ;)


True! But space-time (vacuum) comes close!  ;D

Offline ThinkerX

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Doctor Rodal -  Those seem promising: polished interior, no seams, and designed to withstand a lot of pressure without deforming, hence less hassle from thermal issues.  A couple of those, just eyeballing it, look close to the angles most frequently brought up here. 

Been ages since I worked with these things, but I'm almost willing to bet those same shops would have something that could be finagled into the end plates as well. 

Offline WarpTech

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I have an interesting question / thought experiment in need of some input.

Suppose we have a perfectly conducting cylinder and we inject microwaves into the side, at the center of the cylinder. Their momentum propagates equally in both directions and the reflections result in standing waves. At one end of the cylinder, there is a thin layer of water sealed behind glass which is transparent to microwaves. At the other end, there is a perfect reflector. Should there be NET thrust now? Energy is being used to heat the water on one side, while the other side is receiving all of the momentum that is reflected from it.

The answer is, momentum is NOT conserved in dissipative systems. There should be thrust in proportion to the amount of heat that can be absorbed by the water. It's heat capacity is not infinite so eventually the system becomes polarized, until the water is allowed to cool.

@Rodal mentioned making the cavity a one-way street. Another idea would be to make the frustum out of different metals. Having zinc at one end and copper at the other end will form a galvanic cell, but it also forms a crude diode! This makes it more difficult for current to flow in one direction vs the other direction in the frustum, accomplishing that goal. Different metals can also make it more or less dissipative at each end.

Todd
 

Offline zen-in

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A recent NASA solicitation titled "Utilizing Public - Private partnerships to Advance Tipping Point Technologies"  has a section that request proposals for Small satellite propulsion systems, with funding of up to $2M. 
"Relatively mature or especially novel technology"
 
"NASA is seeking propulsion systems that are ready or nearly ready for demonstration in space, meaning that the offeror could deliver flightready hardware within 6 to 18 months of award. NASA intends to then integrate those systems into CubeSat-scale satellites."

http://nspires.nasaprs.com/external/solicitations/summary.do?method=init&solId={ED1BDB01-28C8-6859-E277-ED206F8B6D68}&path=open

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