Author Topic: EM Drive Developments - related to space flight applications - Thread 3  (Read 1876030 times)

Offline Rodal

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Hard to understand why he continues to write ( http://www.emdrive.com/testnotes.pdf ):

Quote from: Shawyer
The dynamic tests therefore conclusively proved that the engine obeys all Newton’s laws, and that although no reaction mass is required, the engine is not a reactionless machine. Reaction occurs between the EM wave and the reflector surfaces of the resonator, and the law of conservation of momentum is maintained with the transfer of the momentum of the EM wave to the engine

I don't understand why doesn't he get together with someone at a University in the UK to come up with a valid explanation for conservation of momentum, and to explain his experimental results.  We have more than a decade of the scientific community not agreeing with this explanation.
« Last Edit: 06/23/2015 03:12 PM by Rodal »

Offline TheTraveller

Hard to understand why he continues to write ( http://www.emdrive.com/testnotes.pdf ):

Quote from: Shawyer
The dynamic tests therefore conclusively proved that the engine obeys all Newton’s laws, and that although no reaction mass is required, the engine is not a reactionless machine. Reaction occurs between the EM wave and the reflector surfaces of the resonator, and the law of conservation of momentum is maintained with the transfer of the momentum of the EM wave to the engine

I don't understand why doesn't he get together with someone at a University in the UK to come up with a valid explanation for conservation of momentum, and to explain his experimental results.  We have more than a decade of the scientific community not agreeing with this explanation.

Nick seems to agree with Shawyer:

EM momentum moves to the big end, device moves to the small end.

http://physicsfromtheedge.blogspot.com.au/2015/05/emdrive-whence-motion.html?m=1

Quote
So the photons at the wide end have more inertia, and photons gain mass going from the narrow to the wide end. You'll note that mass-energy is not conserved in the usual way here because the horizon causes the zero point field to become real: just as black hole horizons cause virtual particles to become real (Hawking radiation). To conserve momentum the cavity has to move towards the narrow end.
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Offline BL

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I have been reading about several folks building their own 'EmDrives' and trying to figure out how to get power to the drive through a variety of low drag slip rings etc. and wondered what ever happened to Mulletron's idea, way back in the beginning of the original thread, of simply TRANSMITTING the power from a fixed antenna to another antenna on the force measuring apparatus and hooking the output of the receiving antenna to the EmDrive frustum. 

Mulletron reported that his kluged up test link coupled power with a loss on the order of a dB.  Standard gain horns at the frequencies of interest are readily available and a pair of them could certainly couple energy as efficiently as Mulletron's home made rig. 

This plan would have the advantage of not needing any fancy liquid metal slip rings and would remove ALL high current DC, and its attendant potential for introducing spurious thrust, from the vicinity of the test apparatus.  There would be no need for ANY active electronics on the test balance, only the passive receive half of the RF link and the EmDrive frustum. 

If the argument is that thrust would rotate the test rig, misalign the RF link, and reduce the drive to the thruster, that would in itself provide 'proof of principle'.

If the thruster is being tested by using the thrust to load (thrust down) or unload (thrust up) scales, having the thruster sitting on the scales with no physical connection to the off-scale world to worry about would also remove several potential sources of test error.

Another advantage of Mullletron's idea is that if testing is to be done in a vacuum, ALL electronics can be situated outside the vacuum chamber and the RF coupled into the chamber via hermetically sealed feedthroughs.

Yet another advantage is that conventional lab signal sources and amplifiers can be used instead of magnetrons salvaged from microwave ovens, allowing the frequency, power, and spectral content to be tailored to the thruster, and varied as the thruster heats, rather than trying to tweak the frequency response of the thruster mechanically.

At any rate, it seemed to me like a good idea at the time and I wondered why it died so quickly.

Offline TheTraveller

Hard to understand why he continues to write ( http://www.emdrive.com/testnotes.pdf ):

Quote from: Shawyer
The dynamic tests therefore conclusively proved that the engine obeys all Newton’s laws, and that although no reaction mass is required, the engine is not a reactionless machine. Reaction occurs between the EM wave and the reflector surfaces of the resonator, and the law of conservation of momentum is maintained with the transfer of the momentum of the EM wave to the engine

I don't understand why doesn't he get together with someone at a University in the UK to come up with a valid explanation for conservation of momentum, and to explain his experimental results.  We have more than a decade of the scientific community not agreeing with this explanation.

Should  add the scientific community ignored his and the Chinese results. Not good to ignore real world experimental results because the theory was not accepted.
« Last Edit: 06/23/2015 03:31 PM 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 deltaMass

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Why did Shawyer's rig stop accelerating while under continuous power input?

Offline TheTraveller

Why did Shawyer's rig stop accelerating while under continuous power input?

You need to enable the sound and listen to what was said.

It stopped accelerating because the magnetron power supply was switched off.
« Last Edit: 06/23/2015 04:04 PM 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 Rodal

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@Rodal - I have:
 BIG DIAMETER = 0.27246 m
 SMALL DIAMETER = 0.068115 m
 LENGTH =  0.4890240258390259 m
Pardon the extra digits from the calculation.

Running in 3-D with bandwidth opened up to 0.5 * drive frequency (drive = ~1.95GHz), Meep finds 4 frequencies:
1.58530024E+009
1.83409637E+009
2.08402579E+009
2.33698507E+009 Hz
 Q - in order
620.675008923
133.4147313913
1211.3296422825
141.0133154386

This is electric excitation with antenna = 0.2 * wavelength, perpendicular to and centered on the central axis of rotation.


OK - I just read the rest of your post. I'll look for the location of the antenna in the Brady cone, and put it there. But as I recall, that was for exciting a TM mode?

Those dimensions

 BIG DIAMETER = 0.27246 m
 SMALL DIAMETER = 0.068115 m
 LENGTH =  0.4890240258390259 m


have lots of natural frequencies around that range.  Here are just a few, for flat ends:

Mode     frequency (GHz)
TE011   1.73146
TE012   2.0553
TE013   2.3431

TM211  1.9874
TM212  2.40296
TM213  2.72512

TE111  0.965122
TE112  1.24641
TE113  1.50459

TM111 1.51277
TM112 1.89759
TM113 2.20088
Some more frequencies (TE114, TE115 and TE116)

Mode     frequency (GHz)
TE011   1.73146
TE012   2.0553
TE013   2.3431

TM211  1.9874
TM212  2.40296
TM213  2.72512

TE111  0.965122
TE112  1.24641
TE113  1.50459
TE114  1.75336
TE115  1.999
TE116  2.24676

TM111 1.51277
TM112 1.89759
TM113 2.20088

It looks like in this image:



you are exciting mode shape TE115.

Is that the Yang of the Brady extended cone geometry? My results below are for the extended Brady cone geometry

It would be helpful if you could plot the magnetic fields in the cross-direction Hz and the longitudinal direction Hx
« Last Edit: 06/23/2015 05:44 PM by Rodal »

Offline deltaMass

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Why did Shawyer's rig stop accelerating while under continuous power input?

You need to enable the sound and listen to what was said.

It stopped accelerating because the magnetron power supply was switched off.
Do you have the raw data?
Why did the drive frequency keep being changed?
Can we see the time series data for all rotating objects on the cart (on/off/speed)?
« Last Edit: 06/23/2015 05:10 PM by deltaMass »

Offline TheTraveller

Why did Shawyer's rig stop accelerating while under continuous power input?

You need to enable the sound and listen to what was said.

It stopped accelerating because the magnetron power supply was switched off.
Do you have the raw data?
Why did the drive frequency keep being changed?
Can we see the time series data for all rotating objects on the cart (on/off/speed)?

What we have is what we have. Which is more than we had a few hours ago.

As I understand it, the frequency was varied to find rough cavity resonance, then the small end plate length adjuster went to work getting the best possible resonance and highest Q combo.

Seemed to work.
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Offline kdhilliard

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Roger Shawyer kindly sent me a copy of his EMDrive paper that is currently under peer review. All I can say is WOW. All doubt will be removed. Apologises but can't yet share it.

Would make one comment.

The EMDrives on the IXS Clark are old tech, working at only 4N/kW. If  you think the voyage times here

http://emdrive.wiki/Potential_EMDrive_solar_system_explorer_ship

look good, well lets just say they need to be revised downward quite a bit.

Shawyer claims that acceleration causes a decrease in Q which limits the specific thrust to the reciprocal of the velocity: T/P < 1/v.  If he sticks by this, then the specific thrust of any EmDrive will fall below 4N/kW as it accelerates past 250 m/s, so this newer generation drive should not make much of a difference in his calculation of transit times.  IXS Clark transit times, however, come from Eagleworks Lab's (or just Paul March's?) expectation of constant thrust without acceleration-induced degradation of Q.  Under that assumption, every improvement in specific thrust will help.

The only place where I know that Shawyer has specifically addressed spaceship transit times is last month's Daily Mail article: "Its inventor calculates that an interstellar probe would take ten years to reach two-thirds the speed of light, which he sees as pretty much the limit of how fast we could practically travel."  I analyzed that claim here (over on the Feature Article thread) and showed that with T/P < 1/v specific thrust limitation his zero to 2/3 c in 10 years craft would require a power plant which generates at least 97.3 MW/kg.  That is a massive power density and is five orders of magnitude greater than the astounding 1 kW/kg which VASIMR needs for its 39 day trips to Mars.

It is also possible that Shawyer simply forgot to apply his T/P < 1/v when he calculated his interstellar probe acceleration.

It bears repeating here that the T/P < 1/v specific thrust limitation leads only to the appearance of Conservation of Energy in the reference frame from which the EmDrive started accelerating, but that CoE is supposed to be conserved in any inertial reference frame and T/P < 1/v doesn't pull that off.

~Kirk

Offline deltaMass

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Correct. One can write T = P/v until the cows come home, but there's nobody able to say how something disconnected from everything in an asymptotically field-free flat spacetime can know its v-value. If it could, then Einstein's postulate of there being no preferred inertial reference frame is gainsayed, and the jig is up.

However, this does work splendidly for a car tyre on a road.
« Last Edit: 06/23/2015 05:52 PM by deltaMass »

Offline Possibles

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Greetings everyone.

You are all probably going to think I'm a bit mad here...

I had the idea today when I was fed up with thinking about thermal problems and various other artifacts. Also with reversing the experiment to check for thrust. Unfortunately I will also add that actually building what I have in mind is simply going to be too expensive for the hobbyist. So this is going to be more of a thought experiment. I hope that is clear.

What I am proposing is that a spherical capacitor is built. The first, and most desired configuration is that within the first shell, the battery, magnetron, etc... is housed. Heat build up will be a major problem as the inner shell is surrounded by a vacuum so coolant and O2 intake and outtake pipes from the exterior will be needed. The problem here is that the connection to the outside world has to be considered, plus interior interference from the coolant flow etc... The alternative is a one shot system with the interior shell contents supercooled and sealed.

The main purpose of this thought experiment is to ask you guys, and myself included...

How important are the frustum measurements? Can we produce similar effects within two concentric spherical shells containing a vacuum? What will happen?

I know from experience that pointing your eyes and mind somewhere else from time to time can help you realize what you have and haven't got. It can only help.

Mark.

Offline TheTraveller

Correct. One can write T = P/v until the cows come home, but there's nobody able to say how something disconnected from everything in an asymptotically field-free flat spacetime can know its v-value. If it could, then Einstein's postulate of there being no preferred inertial reference frame is gainsayed, and the jig is up.

However, this does work splendidly for a car tyre on a road.

An EMDrive powered ship only knows
A = F/M.

The ship's EMDrive generates the Force, which does Work Accelerating the Mass of the ship over a distance The Energy use to do the work comes from the ship's electrical power supply via the Rf generator.

The ship knows nothing of velocity or KE or distant observers in different reference planes.

As long as the EMDrive can generate the Force and the power supply can deliver the Energy for the Force to do Work on the ship's Mass over a distance, the ship will Accelerate.
« Last Edit: 06/23/2015 06:12 PM 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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Online WarpTech

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Just FYI, I notified Paul March regarding the integration error as soon as I found it. I have nothing personal against Roger Shawyer. His relativistic mathematics is blatantly wrong, anyone can do the math and know it's wrong. There are significant forces on the side walls that cannot be neglected. It appears to me that SPR ignores the correct way to do the math with Maxwell's equations, because it doesn't give him the answer he wants. To me, that is the sign of someone who is either uninterested in understanding it thoroughly, or is trying to hide something or deceive someone. Rather than simply say, "I don't know why it works, but you can see that it does." He's been trying to develop it for over a decade, yet has not made much progress due to his incorrect theory.

Todd

What reply did you receive?

None. We have conversed on other topics but not that one. All in all, as I said the integration was embarrassing but the discrepancy does not effect their conclusions or data. Just their theory.
Todd

Offline TheTraveller

Just FYI, I notified Paul March regarding the integration error as soon as I found it. I have nothing personal against Roger Shawyer. His relativistic mathematics is blatantly wrong, anyone can do the math and know it's wrong. There are significant forces on the side walls that cannot be neglected. It appears to me that SPR ignores the correct way to do the math with Maxwell's equations, because it doesn't give him the answer he wants. To me, that is the sign of someone who is either uninterested in understanding it thoroughly, or is trying to hide something or deceive someone. Rather than simply say, "I don't know why it works, but you can see that it does." He's been trying to develop it for over a decade, yet has not made much progress due to his incorrect theory.

Todd

What reply did you receive?

None. We have conversed on other topics but not that one. All in all, as I said the integration was embarrassing but the discrepancy does not effect their conclusions or data. Just their theory.
Todd

Have a link?
« Last Edit: 06/23/2015 06:15 PM by TheTraveller »
"As for me, I am tormented with an everlasting itch for things remote. I love to sail forbidden seas.”
Herman Melville, Moby Dick

Offline SeeShells

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I like your Chamber and I think your idea may show something of interest once you get your scales stabilized.

On your Resonance chamber have you thought of inserting 2 thin copper sheets down your cavity walls forming a capped off horn as another test? Just a thought.

Shell

Edit.... this was for kml.
« Last Edit: 06/23/2015 06:35 PM by SeeShells »

Online WarpTech

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Just FYI, I notified Paul March regarding the integration error as soon as I found it. I have nothing personal against Roger Shawyer. His relativistic mathematics is blatantly wrong, anyone can do the math and know it's wrong. There are significant forces on the side walls that cannot be neglected. It appears to me that SPR ignores the correct way to do the math with Maxwell's equations, because it doesn't give him the answer he wants. To me, that is the sign of someone who is either uninterested in understanding it thoroughly, or is trying to hide something or deceive someone. Rather than simply say, "I don't know why it works, but you can see that it does." He's been trying to develop it for over a decade, yet has not made much progress due to his incorrect theory.

Todd

What reply did you receive?

None. We have conversed on other topics but not that one. All in all, as I said the integration was embarrassing but the discrepancy does not effect their conclusions or data. Just their theory.
Todd

Have a link?

No. This was a private conversation regarding my warp drive paper and background, not related to the EM Drive.

Regarding F/P = 1/v, I have "just yesterday" found a variation of this equation that requires I consider the 3rd derivative of the magnetic flux, which opposes 1/v. When I have more info, I'll post it but I think I'm onto the equation I tried to derive last month to resolve the paradox. It's just as I said, mc^2/length and length contraction even at relatively low velocity, work to inhibit a higher v and reduce force to zero at constant power. Like pushing on a wall.
Todd
 

Offline Rodal

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@Rodal - I have:
 BIG DIAMETER = 0.27246 m
 SMALL DIAMETER = 0.068115 m
 LENGTH =  0.4890240258390259 m
Pardon the extra digits from the calculation.

Running in 3-D with bandwidth opened up to 0.5 * drive frequency (drive = ~1.95GHz), Meep finds 4 frequencies:
1.58530024E+009
1.83409637E+009
2.08402579E+009
2.33698507E+009 Hz
 Q - in order
620.675008923
133.4147313913
1211.3296422825
141.0133154386

This is electric excitation with antenna = 0.2 * wavelength, perpendicular to and centered on the central axis of rotation.


OK - I just read the rest of your post. I'll look for the location of the antenna in the Brady cone, and put it there. But as I recall, that was for exciting a TM mode?

Those dimensions

 BIG DIAMETER = 0.27246 m
 SMALL DIAMETER = 0.068115 m
 LENGTH =  0.4890240258390259 m


have lots of natural frequencies around that range.  Here are just a few, for flat ends:

Mode     frequency (GHz)
TE011   1.73146
TE012   2.0553
TE013   2.3431

TM211  1.9874
TM212  2.40296
TM213  2.72512

TE111  0.965122
TE112  1.24641
TE113  1.50459

TM111 1.51277
TM112 1.89759
TM113 2.20088
Some more frequencies (TE114, TE115 and TE116)

Mode     frequency (GHz)
TE011   1.73146
TE012   2.0553
TE013   2.3431

TM211  1.9874
TM212  2.40296
TM213  2.72512

TE111  0.965122
TE112  1.24641
TE113  1.50459
TE114  1.75336
TE115  1.999
TE116  2.24676

TM111 1.51277
TM112 1.89759
TM113 2.20088

It looks like in this image:



you are exciting mode shape TE115.

Is that the Yang of the Brady extended cone geometry? My results below are for the extended Brady cone geometry

It would be helpful if you could plot the magnetic fields in the cross-direction Hz and the longitudinal direction Hx
OK, now that I know that you are exciting mode shape TE115, I think I know why one of your cross-views shows the very asymmetric view of the antenna travelling waves, instead of the standing wave field.

Mode shape TE115 is not circumferentially symmetric, but it shows two lobes, see the picture below for the electric vector field

The electric vector field along the horizontal axis going through the center of the cone is zero everywhere, while it is maximum along the vertical axis, at 90 degrees to the horizontal.

Your standing wave plot must be oriented corresponding to my vertical line below, where the standing wave electric field component in the vertical direction is maximum.

Your travelling wave plot for the antenna must be oriented corresponding to my horizontal line below, where the standing wave electric field component in the horizontal direction is zero.  Since the standing wave field is zero, the travelling wave field due to the antenna will show up (however small in magnitude).  Now it would be nice if you could pull up some numbers for both views, to confirm this
« Last Edit: 06/23/2015 06:41 PM by Rodal »

Offline aero

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Quoting from
http://forum.nasaspaceflight.com/index.php?topic=37642.msg1392935#msg1392935

Rodal wrote:
Quote
The electric field must satisfy the boundary conditions of the problem.  The boundary conditions are dictated by copper metal in circular cross-sections, not in Cartesian square cross-sections.

To hope to answer the questions you raise we have to start by understanding what is it that you are plotting.


So far I have understood that:

1) You chose a coordinate Cartesian system that has its origin x=0,y=0,z=0 at the antenna location
No. The coordinate system originates at the center of the cavity, midway between the big and small ends on the axis of rotation of the frustum. The x axis is the axis of rotation, y and z are orthogonal radials. The antenna is centered at (-0.2038, +0.1148, 0) in meters, and lies on y radial, 0.014 meters long.
Quote

2) You chose the x axis to be aligned parallel to the longitudinal axis of symmetry of the cone
The x axis is on the axis of symmetry of the cone.
Quote
3) You chose to plot the component of the Electric field vector in the z direction (Ez), in one of the perpendicular directions to the longitudinal axis of the cone.
I chose to calculate the component of the Electric field vector in the z direction (Ez), z is perpendicular to the longitudinal axis of the cone.
Quote

4) To further understand what you are plotting we need you to answer, for the TE mode:

a) is the component of the electric field in the longitudinal direction Ex, zero in your analysis?  If not, what is the magnitude of Ex compared to Ey and Ez ?

I don't know about you but I just hate it when a co-worker chooses to filter the data before showing it to me. It usually is OK but sometimes it causes all sorts of confusion. guilty  :-[

I have now uploaded the complete set of all of the data slices in the 3 coordinate directions for the ez run. The link is here and I think I've solved the sharing problem so that all you should need is this link.
https://drive.google.com/folderview?id=0B1XizxEfB23tfjVmb1RiZXpaajd6WGpGQmpSWDkxRlV3cG10TEJmWVVEbTd2U0t4MC1aa1E&usp=sharing
Quote

b) can you produce plots of the electric field in the longitudinal direction  Ex in the different cross sections so we see what Ex looks like ?
Done
Quote

c) can you plot the magnetic field in the longitudinal direction Hx, so we can see what it looks like?
Yes, I can to that - it will likely take the rest of the day.
Quote
It will probably take even more plots to understand what you are plotting: Hx, Hy and Ey in the different cross sections.  That's the price one has to pay for using cartesian coordinates (the intrinsic coordinates are spherical because the cone has a circular cross section, rather than a square cross section, and the boundary conditions have to be specified on a circular cross section) and for plotting cartesian components rather than the absolute value of the vector.

Cartesian coordinates are alien, extrinsic to the cone, regardless of the complications of the antenna.

If the Ez field looks symmetric in one cross sectional view, but it looks very unsymmetric at a cross-section rotated by 90 degrees from the symmetric view, somehow the electric field still has to satisfy the boundary conditions along the circumference, and the electric field has to be continuous.

With the present information it is difficult to see how the electric field goes continuously from this:



to this:


by rotating the cross-section by 90 degrees around the longitudinal  x axis of symmetry of the cone, and simultaneously being continuous and satisfying the boundary conditions around the circumference.


I hope the additional data will help answer your concerns and apologize for not posting it earlier. I thought that I had an error somewhere so withheld it.

Unfortunately Meep does not provide spherical coordinates.
Retired, working interesting problems

Offline wallofwolfstreet

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I remember there being some conversation earlier in this thread about whether or not Boeing was conducting Emdrive research in secret.  This aviation week article, from Nov 5th 2012, has a direct quote from a Boeig representative:  http://aviationweek.com/awin/propellentless-space-propulsion-research-continues

Quote
There has been little interest in the EmDrive in the West so far, and Shawyer's government funding has ended. Boeing's Phantom Works, which has previously explored exotic forms of space propulsion, was said to be looking into it some years ago. Such work has evidently ceased. “Phantom Works is not working with Mr. Shawyer,” a Boeing representative says, adding that the company is no longer pursuing this avenue.

So I think it is safe to put to bed the idea that Boeing is working on the Emdrive.  Sorry if this has been posted before.

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