Author Topic: EM Drive Developments - related to space flight applications - Thread 3  (Read 1801289 times)

Offline frobnicat

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As promised, here is my video of the first test of my mechanical fulcrum. It will be used to show relative weight change in addition to a digital scale. Had some concerns about the digital scale alone, possibly being affected by the RF. The fulcrum is simply designed to be an alternate test method.
...

Thank you for posting this !

Great work.

1) I don't know whether it is parallax due to the camera (I would like your feedback) but I saw bending of the wooden beam.  Is the wooden beam compliant enought that the two water bottles are producing visible bending of the beam simply-supported by the knife edge?  If so, you may have two sources of oscillation:

a) lowest frequency oscillation: rigid body rotation of the beam around the knife edge
b) higher frequency oscillation: beam bending oscillations (there are an infinite number, but unless it was parallax I clearly saw beam bending : the first mode)

Couldn't see whether the oscillations were due mainly to rigid body rotation or to bending, but based on the very long period of oscillation, it must be mainly due to rigid body rotation of the beam.

2) If you cannot wait for the oscillations to dampen (>30 minutes ?) in the future, you may have to also include (oil or water) damping.

Yes, the wood is bending and is a source of oscillation besides air currents and end weight rotation. It all becomes stable in abt 30 min, which is fine as my emdrive has abt 6 hour battery life.

On the fulcrum, I cannot perform fast rep-rate testing, simply cw for long duration. The digital scale will be used for that.

Both the main rigid body rotation oscillation period and sensitivity (deviation/force) will depend on the height of centre of mass below the axis. It is below, otherwise the arm wouldn't be stable. The length of strings from which the water bottles hang don't count, since the strings are vertical (same torque around axis whether short or long). The position (height) at which the strings are attached just below the beam + bending downward of the beam are geometric factors that govern the main dynamic and static equilibrium (sensitivity).

Since the beam seems very compliant, the periodic variation of bending (mode b, as per Rodal) will significantly alter the parameters of mode a) : there will be coupling between the two modes a) and b). Maybe it's possible at small cost and small added weight to use a stiffer beam, or make this one stiffer, for instance by triangulating (vertical "mast" fixed orthogonal at centre, two cables slanting from top of it toward both ends of beam).

Offline rfmwguy

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As promised, here is my video of the first test of my mechanical fulcrum. It will be used to show relative weight change in addition to a digital scale. Had some concerns about the digital scale alone, possibly being affected by the RF. The fulcrum is simply designed to be an alternate test method.
...

Thank you for posting this !

Great work.

1) I don't know whether it is parallax due to the camera (I would like your feedback) but I saw bending of the wooden beam.  Is the wooden beam compliant enought that the two water bottles are producing visible bending of the beam simply-supported by the knife edge?  If so, you may have two sources of oscillation:

a) lowest frequency oscillation: rigid body rotation of the beam around the knife edge
b) higher frequency oscillation: beam bending oscillations (there are an infinite number, but unless it was parallax I clearly saw beam bending : the first mode)

Couldn't see whether the oscillations were due mainly to rigid body rotation or to bending, but based on the very long period of oscillation, it must be mainly due to rigid body rotation of the beam.

2) If you cannot wait for the oscillations to dampen (>30 minutes ?) in the future, you may have to also include (oil or water) damping.

Yes, the wood is bending and is a source of oscillation besides air currents and end weight rotation. It all becomes stable in abt 30 min, which is fine as my emdrive has abt 6 hour battery life.

On the fulcrum, I cannot perform fast rep-rate testing, simply cw for long duration. The digital scale will be used for that.

Both the main rigid body rotation oscillation period and sensitivity (deviation/force) will depend on the height of centre of mass below the axis. It is below, otherwise the arm wouldn't be stable. The length of strings from which the water bottles hang don't count, since the strings are vertical (same torque around axis whether short or long). The position (height) at which the strings are attached just below the beam + bending downward of the beam are geometric factors that govern the main dynamic and static equilibrium (sensitivity).

Since the beam seems very compliant, the periodic variation of bending (mode b, as per Rodal) will significantly alter the parameters of mode a) : there will be coupling between the two modes a) and b). Maybe it's possible at small cost and small added weight to use a stiffer beam, or make this one stiffer, for instance by triangulating (vertical "mast" fixed orthogonal at centre, two cables slanting from top of it toward both ends of beam).

I like the vertical mast idea to dampen oscillations. Like Doc says, I could also suspend a flat plate in oil at ground level to help. Long moment arms do have their quirks  :o

Offline aero

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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?
« Last Edit: 06/22/2015 01:05 AM by aero »
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Online SeeShells

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As promised, here is my video of the first test of my mechanical fulcrum. It will be used to show relative weight change in addition to a digital scale. Had some concerns about the digital scale alone, possibly being affected by the RF. The fulcrum is simply designed to be an alternate test method.
...

Thank you for posting this !

Great work.

Since the beam seems very compliant, the periodic variation of bending (mode b, as per Rodal) will significantly alter the parameters of mode a) : there will be coupling between the two modes a) and b). Maybe it's possible at small cost and small added weight to use a stiffer beam, or make this one stiffer, for instance by triangulating (vertical "mast" fixed orthogonal at centre, two cables slanting from top of it toward both ends of beam).
PERFECT!!! I was trying to play catch up asI was away and was just thinking of ways you could stiffen it. I think the cable idea is perfect. Nice.

Shell

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?
I can't run this now, as I'm working on a project.  My two Mathematica machines are running other calculations at the moment. Will try to run it tomorrow.

Either the 2.08402579E+009 or 2.33698507E+009 Hz may be the TE012 mode I think (from my memory, remember the case where they run without dielectric and they could not get a measurable thrust ?)

<<We performed some very early evaluations without the dielectric resonator (TE012 mode at 2168 MHz, with power levels up to ~30 watts) and measured no significant net thrust.>>

Whether you excite a TE mode or a TM mode, I would NOT move the antenna as you extend the cone towards the vertex.  If you look at my report, the electric fields do NOT move into the pointy side of the cone.  Thus the antenna will be ineffective there.

The antenna location should be kept in the original Brady position in fixed position, whether in the TE orientation or the TM orientation.  Do not move the antenna as you extend the cone.
« Last Edit: 06/22/2015 01:56 AM by Rodal »

Offline Rodal

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splad posted this great video on Reddit:

https://www.youtube.com/watch?v=L5fVFA2sWt4&feature=youtu.be

Acoustic Propulsion

Notice that you must have an open end for this to work.  Prof. Uno Ingard showed this in his classic book with puffs of smoke coming out of the bottle.  I remember Uno Ingard at MIT, Professor in both the Physics and the Aero and Astro departments.  Great teacher .

Look at 3:20 into the film for the puffs of smoke to come out

You must have mass/energy coming out of the EM Drive to have any propulsion, as well.

This is a great test to show that Shawyer is wrong (justifying the EM Drive on resonance, and claiming that no esoteric physics is needed to have propulsion without anything coming out): if you put a cap on the bottles, they will not spin, as there is no air coming out, it is an ASYMMETRIC RESONATOR.  It needs to have an open end for it to work.

EDIT: Acoustic propulsion works because the exhaust of gas (due to compression of the plastic bottle during acoustic vibration) occurs in well-directed vortices while the intake of gas (due to the expansion phase of the plastic bottle during acoustic vibration) is not as axially directed but instead it sucks air from a large range of directions, including the direction perpendicular to the axis of axisymmetry of the bottle.   In other words, acoustic propulsion works due to the difference between ejection flow and intake flow.


More on acoustic propulsion:



« Last Edit: 06/22/2015 02:39 PM by Rodal »

Offline deltaMass

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Dear rfmwguy,
  a table to put the camera down on may make adjusting things easier as it will allow you to use both hands.

A table or a tripod. Unless you are filming with your cell phone  :)
@rfmwguy: How many kilos did you plan hanging off that splendid piece of wood?  ???
I seem to recall you wanted to make this self-contained and battery operated (or was that TheTraveller?).
How much RF power will you use?
For what sort of thrust magnitude are you planning?
« Last Edit: 06/22/2015 02:12 AM by deltaMass »

Offline WarpTech

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I attach my report

first attachment below, titled:

Cut-off of Resonant Modes in Truncated Conical Cavities

Conclusions
...

This is a great piece of work Jose. It shows what can be learned when a problem thoroughly tackled and we don't just copy and paste what someone else did. I've got to analyze this myself some more. I'm working on my DC analysis and I've made significant progress. It's not ready yet, but I think it will be interesting.

Todd

Offline WarpTech

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As promised, here is my video of the first test of my mechanical fulcrum. It will be used to show relative weight change in addition to a digital scale. Had some concerns about the digital scale alone, possibly being affected by the RF. The fulcrum is simply designed to be an alternate test method.
...

Thank you for posting this !

Great work.

1) I don't know whether it is parallax due to the camera (I would like your feedback) but I saw bending of the wooden beam.  Is the wooden beam compliant enought that the two water bottles are producing visible bending of the beam simply-supported by the knife edge?  If so, you may have two sources of oscillation:

a) lowest frequency oscillation: rigid body rotation of the beam around the knife edge
b) higher frequency oscillation: beam bending oscillations (there are an infinite number, but unless it was parallax I clearly saw beam bending : the first mode)

Couldn't see whether the oscillations were due mainly to rigid body rotation or to bending, but based on the very long period of oscillation, it must be mainly due to rigid body rotation of the beam.

2) If you cannot wait for the oscillations to dampen (>30 minutes ?) in the future, you may have to also include (oil or water) damping.

Yes, the wood is bending and is a source of oscillation besides air currents and end weight rotation. It all becomes stable in abt 30 min, which is fine as my emdrive has abt 6 hour battery life.

On the fulcrum, I cannot perform fast rep-rate testing, simply cw for long duration. The digital scale will be used for that.

A plunger and a bucket of oil will really help damp those oscillations, and it should not affect any displacement if there is real thrust, and proper counterbalance.
Todd

Offline Rodal

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I attach my report

first attachment below, titled:

Cut-off of Resonant Modes in Truncated Conical Cavities

Conclusions
...

This is a great piece of work Jose. It shows what can be learned when a problem thoroughly tackled and we don't just copy and paste what someone else did. I've got to analyze this myself some more. I'm working on my DC analysis and I've made significant progress. It's not ready yet, but I think it will be interesting.

Todd

Thank you, much appreciated :)

Offline rfmwguy

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Dear rfmwguy,
  a table to put the camera down on may make adjusting things easier as it will allow you to use both hands.

A table or a tripod. Unless you are filming with your cell phone  :)
@rfmwguy: How many kilos did you plan hanging off that splendid piece of wood?  ???
I seem to recall you wanted to make this self-contained and battery operated (or was that TheTraveller?).
How much RF power will you use?
For what sort of thrust magnitude are you planning?

Budget is 1.5 kg 8 watts and 12 cubic inches

Offline Acryte

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Dr. Rodal very cool videos.

I'm sure it' a dumb idea but it comes to mind for a low cost setup for the baby EM drive... Can we use sound waves to lock them into a controlled spin? Could they possibly Have 2 setups contained in 2 separate large plastic or glass containments (to reduce problems with drafts), then use sound to control the initial starting conditions of each setup... cheaply, you could probably use a magnet to hold them at an identical starting position then remove it and then start to spin it with sound... I think you could control the setup with decent precision and have them operating synchronously... We use some setup for the base that damps vibrations or possibly have both setups hang from the ceiling? With both devices synced up we kill the sound and then we turn one of the baby EM Drives on and measure any significant deviation between the two setups.

We could also capture video of both setups and analyze the difference with video software... all you'd need for a basic setup are 2 displays both provided the same video source that has a clock counting up at idk 120hz and then you can have 2 individual cameras take the video and syncing up and comparing them later would be simple.

Would the expelled air from the bottle or whatever open container is used as a thruster be too chaotic to have in a closed environment? Would it overwhelm the possibility of making any significant measurements or would each setup operate in a relatively controlled manner?
« Last Edit: 06/22/2015 04:00 AM by Acryte »

Offline deltaMass

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Dear rfmwguy,
  a table to put the camera down on may make adjusting things easier as it will allow you to use both hands.

A table or a tripod. Unless you are filming with your cell phone  :)
@rfmwguy: How many kilos did you plan hanging off that splendid piece of wood?  ???
I seem to recall you wanted to make this self-contained and battery operated (or was that TheTraveller?).
How much RF power will you use?
For what sort of thrust magnitude are you planning?

Budget is 1.5 kg 8 watts and 12 cubic inches
12 cubic inches of thrust should be readily detectable with your set-up I think.

Offline demofsky

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Just came across a very interesting paper;

http://arxiv.org/pdf/0708.3519.pdf

Photons inside a waveguide as massive particles
Zhi-Yong Wang1, Cai-Dong Xiong
"In the paper, we show that there exists a close analogy between the behavior of de
Broglie matter waves and that of electromagnetic waves inside a hollow waveguide, such that the guided photons can be treated as free massive particles subject to a relativistic quantum-mechanical equation. Inspired by the effective rest mass of guided photons and the zitterbewegung phenomenon of the Dirac electron, at variance with the well-known Higgs mechanism we present some different heuristic ideas on the origin of mass."

So, apparently photons in a waveguide may be treated identically to De Broglie waves of massive particles. The photons have a rest mass determined by the waveguide cut-off where vg => 0;

mphoton = h/cλc

and have relativistic momentum;

p = mphoton*vg/√(1 - (vg/c)2)

As the waves reach the cut-off end of the waveguide, their momentum goes to zero and the frustum must gain that amount of rest mass. This process should happen with a magnetron, because the output is a Negative E-field, pulsed at 60Hz (or 50Hz) and this negative value exponentially decays to zero. The magnetron's microwaves have a negative DC bias, right out of the gun.

http://www.cpii.com/docs/related/2/Mag%20tech%20art.pdf

I believe that this process stores mass at the front of the frustum that builds over time, walking the CM forward until there is enough pressure to push it. The resonant microwaves, IMO like Greg Egan, have nothing to do with the thrust. The Q when using a magnetron however, may be proportional the stored DC current level as well as the resonance since both will grow together until heat losses overcome the addition of more current. It is essentially, charging up an inductor, L,

dI(t) = (V/L)dt

In this case, f = 60Hz, not GHz.

The force dF = B.H*dS  (S for area), is due to the B-field pressure, which escapes through the copper because it is DC. The AC skin effect does not apply so the field cannot be shielded by copper.
Todd

Quote
As the waves reach the cut-off end of the waveguide, their momentum goes to zero and the frustum must gain that amount of rest mass. This process should happen with a magnetron, because the output is a Negative E-field, pulsed at 60Hz (or 50Hz) and this negative value exponentially decays to zero.

So could this be reinterpreted to say that the duty cycle of the magnetron is an important factor? 

I ask this specific question to highlight the fact that the duty cycle "comes out of the box" with magnetrons and could be a factor vs. the nice continuous CW experiments that don't produce much thrust. 

I can't recall anyone doing any deliberate modulation/pulsing of the power input so I want to highlight this for everyone's consideration.

(I am catching up on this thread so apologies for the late question for this post.)
« Last Edit: 06/22/2015 07:08 AM by demofsky »

Offline Rodal

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Offline Rodal

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Dr. Rodal very cool videos.

I'm sure it' a dumb idea but it comes to mind for a low cost setup for the baby EM drive... Can we use sound waves to lock them into a controlled spin? Could they possibly Have 2 setups contained in 2 separate large plastic or glass containments (to reduce problems with drafts), then use sound to control the initial starting conditions of each setup... cheaply, you could probably use a magnet to hold them at an identical starting position then remove it and then start to spin it with sound... I think you could control the setup with decent precision and have them operating synchronously... We use some setup for the base that damps vibrations or possibly have both setups hang from the ceiling? With both devices synced up we kill the sound and then we turn one of the baby EM Drives on and measure any significant deviation between the two setups.

We could also capture video of both setups and analyze the difference with video software... all you'd need for a basic setup are 2 displays both provided the same video source that has a clock counting up at idk 120hz and then you can have 2 individual cameras take the video and syncing up and comparing them later would be simple.

Would the expelled air from the bottle or whatever open container is used as a thruster be too chaotic to have in a closed environment? Would it overwhelm the possibility of making any significant measurements or would each setup operate in a relatively controlled manner?
An external bottle containing the EM Drive inside it, could indeed be used to impart a velocity, but so could other means be used to impart a velocity to the EM Drive.  The expelled air from the bottle has been shown by Prof. Uno Ingar to feature nice looking vortices that are pulsed as per acoustic frequency of the bottle.  In this case the EM Drive inside the bottle would change the acoustics of the bottle so that the acoustic natural frequency of the bottle with the EM Drive inside it would be different from the acoustic frequency of an empty bottle. 

NOTE: Acoustic propulsion works because the exhaust of gas (due to compression of the plastic bottle during acoustic vibration) occurs in well-directed vortices while the intake of gas (due to the expansion phase of the plastic bottle during acoustic vibration) is not as axially directed but instead it sucks air from a large range of directions, including the direction perpendicular to the axis of axisymmetry of the bottle.   In other words, acoustic propulsion works due to the asymmetry between the ejection flow (well directed in axial flow) and intake flow (practically omnidirectional) phases of the bottle's oscillation.
« Last Edit: 06/22/2015 03:01 PM by Rodal »

Offline Rodal

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...
I can't recall anyone doing any deliberate modulation/pulsing of the power input so I want to highlight this for everyone's consideration.

(I am catching up on this thread so apologies for the late question for this post.)
Paul March from NASA discussed frequency, amplitude and phase modulation produced by the Magnetron in NSF EM Drive Thread 2.   He showed the results of Dr. White's computer analysis (based on his QV theory) to the effect that the modulation provided by the Magnetron should result in much greater thrust as per White's theory.  Therefore they designed a series of tests to be run with Magnetron providing modulation, that are scheduled to be run this Summer.

Offline OttO

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An article that could be interesting:

http://arxiv.org/abs/1410.1445

Position and Spin Operators, Wigner Rotation and the Origin of Hidden Momentum Forces

in special relativity, there are two rest systems for the particle, zero velocity and zero
momentum,........If the magnetic moment is interacting with a pointlike electric charge e, then the electric field ~E created gives rise to a force e~

Offline rfmwguy

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Dear rfmwguy,
  a table to put the camera down on may make adjusting things easier as it will allow you to use both hands.

A table or a tripod. Unless you are filming with your cell phone  :)
@rfmwguy: How many kilos did you plan hanging off that splendid piece of wood?  ???
I seem to recall you wanted to make this self-contained and battery operated (or was that TheTraveller?).
How much RF power will you use?
For what sort of thrust magnitude are you planning?

Budget is 1.5 kg 8 watts and 12 cubic inches
12 cubic inches of thrust should be readily detectable with your set-up I think.

Sorry, thrust estimate in the 185 mg range I believe is what the spreadsheet said...snarky comment accepted ;)

Offline Rodal

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...Sorry, thrust estimate in the 185 mg range I believe is what the spreadsheet said...snarky comment accepted ;)
What formula are you using to estimate the thrust force as 185 mg and what were the input parameters you used for the formula?
« Last Edit: 06/22/2015 03:01 PM by Rodal »

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