Author Topic: EM Drive Developments - related to space flight applications - Thread 3  (Read 1798916 times)

Offline X_RaY

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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.



Nice idea and verry cheap but its tricky intricate and it cost a lot of time with such setup. I wonder  ??? why nobody come up with the idea to use realy good laboratory scales, for example up to 10kg( for cone and magnetron) and a precision of ~50mg.


https://www.pce-instruments.com/english/?id=55870f0216498200&_baseurl=%2Fenglish&action=ShowItem&_list=qr.art&_listpos=1&_artnr=345622
« Last Edit: 06/21/2015 07:41 PM by X_RaY »

Offline SeeShells

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Need to go visit today, but before I did I thought you would like to see the first draft of the segmented, multi end plate, perforated copper frustum. Using clasps to hold the to parts together and they should be quite secure and sturdy. The large endplate will be cupped out with an english wheel the small top plates will be flat.

Shell

Waiting to see the patterns from Aero to finally decide on the antenna orientation. BTW Aero great work!!!

Edit: forgot pic... ;)
« Last Edit: 06/21/2015 07:29 PM by SeeShells »

Offline Rodal

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Need to go visit today, but before I did I thought you would like to see the first draft of the segmented, multi end plate, perforated copper frustum. Using clasps to hold the to parts together and they should be quite secure and sturdy. The large endplate will be cupped out with an english wheel the small top plates will be flat.

Shell

Waiting to see the patterns from Aero to finally decide on the antenna orientation. BTW Aero great work!!!

Edit: forgot pic... ;)

It looks great !!! :)

Please wait until you read my paper (coming out soon, today) as that cone maybe too pointy, you want to be able to terminate it a little further from the vertex of the cone.

Offline DaCunha

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Dear all,

In 2012 the first solid state maser based on a pentacene doped t-terphenyl crystal was invented at the Imperial College London after 60 years of unsuccessful attempts to build a maser that is capable of emitting at ambient conditions with considerable output powers.

It's maximal output power in Continous mode is 0.1 mW and approx. 1 W in a microsecond pulsed mode.

Now what do you think about the following?

What if we manage to amplify such a 1 W peak power pulse with a pulse duration of a microsecond  and amplify it with a klystron to much higher peak powers?


If the effect that shortened the optical path length of the laser pulse (as measured from laboratory frame), is dependent on the electric field strength, then we could amplify this effect for the duration of the pulse.

Now IF, the laser pulse is just triggered to pass through the frustum just when the pulse is being reflected, we should see a much stronger effect of path length shortening... well at least IF the assumption that the effect is dependent on electric and magnetic field strength is correct...

I have the feeling that spatial coherence of the microwave input of the EMDrive plays an important role that has not been taken into account until now. Thus the maser could help a lot..

Do you think that beside the electric field amplitude also the phase of the field is playing a role for the EMDrive effect?
« Last Edit: 06/21/2015 07:54 PM by DaCunha »

Offline Rodal

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Dear all,

In 2012 the first solid state maser based on a pentacene doped t-terphenyl crystal was invented at the Imperial College London after 60 years of unsuccessful attempts to build a maser that is capable of emitting at ambient conditions with considerable output powers.

It's maximal output power in Continous mode is 0.1 mW and approx. 1 W in a microsecond pulsed mode.

Now what do you think about the following?

What if we manage to amplify such a 1 W peak power pulse with a pulse duration of a microsecond  and amplify it with a klystron to much higher peak powers?


If the effect that shortened the optical path length of the laser pulse (as measured from laboratory frame), is dependent on the electric field strength, then we could amplify this effect for the duration of the pulse.

Now IF, the laser pulse is just triggered to pass through the frustum just when the pulse is being reflected, we should see a much stronger effect of path length shortening... well at least IF the assumption that the effect is dependent on electric and magnetic field strength is correct...

Welcome to the forum and thank you for a fantastic contribution.

I think that your proposal is a great idea !  :)

I have been campaigning for the Aachen fellow to fill the Baby EM Drive with Ammonia so that it can emit at the 24 GHz frequency they are operating at, to see whether that results in any detectable thrust force

Offline aero

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The final 8 .pngs, Yang cavity electric excitation, antenna length = 0.2 wavelengths, total run 16 periods with .png output every 0.2 periods.

This set of images is much better behaved than the magnetic excited cavity images. Don't know why. Unfortunately, with the background changing color as it does, a movie wouldn't be very viewable. IMO

I'll go ahead and upload this complete set to my Google Drive in case anyone is interested in looking at them all together. I point out that there are patterns that appear across the whole set that don't pop out at you when looking at only a small subset of the images.
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Offline Rodal

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The final 8 .pngs, Yang cavity electric excitation, antenna length = 0.2 wavelengths, total run 16 periods with .png output every 0.2 periods.

This set of images is much better behaved than the magnetic excited cavity images. Don't know why. Unfortunately, with the background changing color as it does, a movie wouldn't be very viewable. IMO

I'll go ahead and upload this complete set to my Google Drive in case anyone is interested in looking at them all together. I point out that there are patterns that appear across the whole set that don't pop out at you when looking at only a small subset of the images.

This is great !!!

It predicts mode shape TE012, same mode that my exact solution predicts  :)

Offline aero

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The final 8 .pngs, Yang cavity electric excitation, antenna length = 0.2 wavelengths, total run 16 periods with .png output every 0.2 periods.

This set of images is much better behaved than the magnetic excited cavity images. Don't know why. Unfortunately, with the background changing color as it does, a movie wouldn't be very viewable. IMO

I'll go ahead and upload this complete set to my Google Drive in case anyone is interested in looking at them all together. I point out that there are patterns that appear across the whole set that don't pop out at you when looking at only a small subset of the images.

This is great !!!

It predicts mode shape TE012, same mode that my exact solution predicts  :)

It predicts mode shape TE012, same mode that my exact solution predicts

I am glad to hear that!  Emphatically GLAD to hear that.
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Offline Rodal

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I attach my report

first attachment below, titled:

Cut-off of Resonant Modes in Truncated Conical Cavities

Conclusions

1) It is nonsense to use a cylindrical waveguide cut-off formula to predict cut-off of mode shapes in a truncated cone. Truncated cones cannot have constant electromagnetic fields in the longitudinal direction, thus the use of cylindrical waveguide formulas (which assume constant cross-sections) for truncated cone cavities is nonsense.

2) Truncated cones show an absence of sharp cut-off frequencies. Cut-off occurs at geometries that are close to a pointy cone, at small base dimensions that are much smaller than what is predicted by cylindrical waveguide cut-off formulas.

3) On the contrary, continuing the cone beyond the small diameter at which cut-off would occur (according to the cylindrical formula which is inapplicable to the cone) leads to significantly higher amplitudes of the electromagnetic fields. The amplitude of mode TE013 actually increases by a factor greater than 2.5 from its original amplitude.  While mode shape TE013 has the smallest amplitude compared to TE011 and TE012 at the initial dimensions, as we reduce the small base it becomes the mode with the highest amplitude

4) The “half-wavelength” nearest the apex gets longer as it approaches the apex.

5) For the particular geometry in the examples in this report, cut-off of mode shape TE011 occurs when the small base is reduced to only ¼ of its original dimension.  The cut-off condition based on a cylindrical waveguide incorrectly shows that TE011 should have been cut-off at a much larger base diameter (at 0.90 the original dimension instead of 0.25 the original dimension).

6) Cut-off of mode shape TE012 and TE013 occurs when the small base is reduced to only 1/5 of its original dimension.  The cut-off condition based on a cylindrical waveguide incorrectly shows that TE012 and TE013 should have been cut-off at a much larger base diameter (at 0.90 the original dimension instead of 0.20 the original dimension).

7) Continuing the cone up to distances much closer to the apex also results in lower phase shift and higher geometrical attenuation of the electromagnetic field in the longitudinal direction. When the small base is reduced to ½ the original size: a) the (dimensionless) geometrical attenuation is increased by a factor of 28 times from 0.1 to 2.8, and b) the phase constant is increased by a factor of 2 from 0.5 to 1.  Hence it looks like very large changes can be accomplished by simply reducing a truncated cone’s small base so that it is much closer to the cone’s apex, and this can be done without incurring cut-off, and achieving a higher amplitude to boot. Thus continuing the cone beyond the cylindrical cut-off frequency may result in very interesting behavior.

8) All the EM Drive formulas (McCulloch’s, @Notsosureofit’s, and Shawyer’s) predict greater thrust with a larger difference between the diameters of the big and the small bases of the truncated cone.  Therefore these formulas point towards the direction that the ideal geometry would be one with a small base diameter.  Yet such a geometry has not been explored up to now, apparently due to Shawyer’s constraining the small base diameter to be larger than the diameter that results in cut-off according to the cylindrical waveguide formula.  This report shows that this constraint is nonsensical, as truncated cones resonate (and at higher amplitude) with significantly smaller base diameters.  This report shows that the small based diameter could be reduced to at least ½ of its present size, and perhaps to 1/5 of its present size.
« Last Edit: 06/21/2015 08:26 PM by Rodal »

Offline Rodal

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...

I am glad to hear that!  Emphatically GLAD to hear that.

At what frequency is your cone being excited in those images?
« Last Edit: 06/21/2015 08:17 PM by Rodal »

Offline SeeShells

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I attach my report

first attachment below, titled:

Cut-off of Resonant Modes in Truncated Conical Cavities

Conclusions

1) It is nonsense to use a cylindrical waveguide cut-off formula to predict cut-off of mode shapes in a truncated cone. Truncated cones cannot have constant electromagnetic fields in the longitudinal direction, thus the use of cylindrical waveguide formulas (which assume constant cross-sections) for truncated cone cavities is nonsense.

2) Truncated cones show an absence of sharp cut-off frequencies. Cut-off occurs at geometries that are close to a pointy cone, at small base dimensions that are much smaller than what is predicted by cylindrical waveguide cut-off formulas.

3) On the contrary, continuing the cone beyond the small diameter at which cut-off would occur (according to the cylindrical formula which is inapplicable to the cone) leads to significantly higher amplitudes of the electromagnetic fields. The amplitude of mode TE013 actually increases by a factor greater than 2.5 from its original amplitude.  While mode shape TE013 has the smallest amplitude compared to TE011 and TE012 at the initial dimensions, as we reduce the small base it becomes the mode with the highest amplitude

4) The “half-wavelength” nearest the apex gets longer as it approaches the apex.

5) For the particular geometry in the examples in this report, cut-off of mode shape TE011 occurs when the small base is reduced to only ¼ of its original dimension.  The cut-off condition based on a cylindrical waveguide incorrectly shows that TE011 should have been cut-off at a much larger base diameter (at 0.90 the original dimension instead of 0.25 the original dimension).

6) Cut-off of mode shape TE012 and TE013 occurs when the small base is reduced to only 1/5 of its original dimension.  The cut-off condition based on a cylindrical waveguide incorrectly shows that TE012 and TE013 should have been cut-off at a much larger base diameter (at 0.90 the original dimension instead of 0.20 the original dimension).

7) Continuing the cone up to distances much closer to the apex also results in lower phase shift and higher geometrical attenuation of the electromagnetic field in the longitudinal direction. When the small base is reduced to ½ the original size: a) the (dimensionless) geometrical attenuation is increased by a factor of 28 times from 0.1 to 2.8, and b) the phase constant is increased by a factor of 2 from 0.5 to 1.  Hence it looks like very large changes can be accomplished by simply reducing a truncated cone’s small base so that it is much closer to the cone’s apex, and this can be done without incurring cut-off, and achieving a higher amplitude to boot. Thus continuing the cone beyond the cylindrical cut-off frequency may result in very interesting behavior.

8) All the EM Drive formulas (McCulloch’s, @Notsosureofit’s, and Shawyer’s) predict greater thrust with a larger difference between the diameters of the big and the small bases of the truncated cone.  Therefore these formulas point towards the direction that the ideal geometry would be one with a small base diameter.  Yet such a geometry has not been explored up to now, apparently due to Shawyer’s constraining the small base diameter to be larger than the diameter that results in cut-off according to the cylindrical waveguide formula.  This report shows that this constraint is nonsensical, as truncated cones resonate (and at higher amplitude) with significantly smaller base diameters.  This report shows that the small based diameter could be reduced to at least ½ of its present size, and perhaps to 1/5 of its present size.

If you notice that I have setting beside my design several small end cone inserts. Even though the cone goes to a small 1" opening. I believe what is beyond the small endplate should have no effect to the harmonics between the endplates.

I've moved the lead screw to the back of the large plate for fine tuning.

Shell

Offline aero

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...

I am glad to hear that!  Emphatically GLAD to hear that.

At what frequency is your cone being excited in those images?

Drive is set at 2.45 GHz. I haven't made any resonance runs in this excitation/antenna configuration. I could do that.

I could, but I'd like to take the time to digest your paper and perhaps model a cavity designed as you suggest. For flat end plates, making a model would be very simple. For "spherical section" end plates I'd need to write a new control file but that wouldn't be so difficult as I've done it before. Do need to know the radii though, and the best half angle.
« Last Edit: 06/21/2015 08:41 PM by aero »
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Offline Rodal

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I am glad to hear that!  Emphatically GLAD to hear that.

At what frequency is your cone being excited in those images?

Drive is set at 2.45 GHz. I haven't made any resonance runs in this excitation/antenna configuration. I could do that.

I could, but I'd like to take the time to digest your paper and perhaps model a cavity designed as you suggest. For flat end plates, making a model would be very simple. For "spherical section" end plates I'd need to write a new control file but that wouldn't be so difficult as I've done it before. Do need to know the radii though, and the best half angle.

You don't need to have spherical ends, the difference between spherical and flat is only like 1% for NASA truncated cone.

I advise you use flat ends.

In my paper I think I have the dimensions of flat bases, both small and big diameter, as well as the length between them.  If something is missing please just ask :)

Offline zen-in

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...

electromagnetic interaction of the supply wires? I wasn't aware copper was that magnetic.  I mean, unless I don't understand what you are saying.  Interaction with what?

Any conductor that has a current in it produces a magnetic field that can interact with permanent magnets or other current-carrying wires.   This was discovered by Hans Christian Ørsted almost 200 years ago and was later studied by Michael Faraday.  Two parallel wires that carry current in the same direction will attract each other.   In the case of wires used to supply power to an apparatus, the currents would always be in opposite directions so the wires would repel each other.  This repelling force produces a secondary force due to the decreased length of the two conductors as a result of the bending.   I have observed all of this.     When an apparatus is suspended from a balance and wires are used to power said apparatus it is not always apparent what the effects of these forces will be.   But these forces will be there and they are almost impossible to null them out.   It doesn't matter if the wire is carrying AC or DC; the same force is produced.   Also a dual conductor cable (like an AC zipline) is not immune to these effects.   Heat generated in the wires has the opposite effect.   The effective wire length increase when it is heated because of expansion of the Copper and softening of the insulation.

http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/wirfor.html
« Last Edit: 06/21/2015 10:05 PM by zen-in »

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.

Offline A_M_Swallow

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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.

Offline aero

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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  :)
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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  :)

Yes, just a cellphone. I plan on using a tripod and webcam for the live video stream in july. Test today was simply to discover if I could get deflection in milligram range. Thanks for advice.
« Last Edit: 06/22/2015 12:23 AM by rfmwguy »

Offline aero

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Dr. Rodal,

What drive frequency do you propose? Shown is ~ 1.95 GHz. It's an extended Brady cone, with small end = 0.25*big end. That is, sf= 0.25, small = sf * big, and new_height = height*big*(1-sf)/(big-small). I guess I'll make a resonance run to see if something comes up.
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Offline Rodal

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Dr. Rodal,

What drive frequency do you propose? Shown is ~ 1.95 GHz. It's an extended Brady cone, with small end = 0.25*big end. That is, sf= 0.25, small = sf * big, and new_height = height*big*(1-sf)/(big-small). I guess I'll make a resonance run to see if something comes up.
For the extended Baby EM Drive I have a spreadsheet with dimensions and corresponding frequencies on page 10 of my report "Cut-Off of resonant..."

For other dimensions, I need you to give  me:

(please specify inches or meters, or whatever dimension you use)

BIG DIAMETER =   

SMALL DIAMETER =

LENGTH =

and I'll run the calculations.

(I rather don't assume what you mean by Brady cone, as even Paul used slightly different numbers).

Roughly speaking, keeping the same cone angle and extending the cone the frequency goes down just a little, for the same mode.

It looks like you are exciting another mode there with a high "p"

The antenna seems to be too far towards the apex into the cone.  It should be much closer to the big end.

Keep the antenna in the original Brady location.  Do NOT move the antenna as you extend the cone
« Last Edit: 06/22/2015 12:06 AM by Rodal »

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