Author Topic: EM Drive Developments - related to space flight applications - Thread 3  (Read 1801288 times)

Offline aero

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You may recall that yesterday I posted some meep generated data including the first attached image. I claimed force/power ~ 5/c based on the model run as the model existed at that time. That was all wrong.

I let myself get in a hurry and didn't do enough debugging. The image from the corrected model is attached, followed by an image of the cavity debug mark-up. This corrected model gives force/power ~ 0.85/c, which is not spectacular at all but interesting none the less. Interesting, because one would expect the force on the plus and minus ends of the cavity to cancel out. Meep does calculate the sum of forces in the positive and negative direction from a plane wave source as exactly zero. (Using the control file attached.)

Now, for those who are interested, I have attached my corrected control file. The problem with the version I was using yesterday (and I have posted here on NSF) was that the computational lattice was not large enough. The corner of the big end of the frustum was very near or within the PML boundary layer. This damped RF energy moving in that direction so the wave paterns looked as they did and the force/power was dominated by only one end. Hopefully none of you will ever make such a mistake. Making the computational lattice smaller will result in faster runs, but it's hardly worth the embarrassment.
Retired, working interesting problems

Offline TheTraveller

WE HAVE RESONANCE!

Attached is TE01x analysis for the Baby EM Drive.

With flat end plates, length resonance can occur anywhere from

the min spacing of:

1) centre of big end plate to centre of small end plate

to max spacing of :

2) outer edge big end plate to outer edge small end plate.

As you can see TE013 generates a length resonance ring just inside the maximal outer edge spacing.

For the Baby EM Drive, there are several resonance modes. Which is driven depends on excitation method, antenna placement and antenna design.

Spreadsheet attached.
« Last Edit: 06/15/2015 02:01 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 PaulF

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BabyEM is small enough to have the whole contraption enclosed in a relatively small vacuum chamber. Going on the fact that BabyEM is only a few cm long, the whole contraption seems between 25 and 30 cm long to me. With a bit of redesign it could easily fit in a small chamber which is easier to get than a large one.

Ding tests in a vacuum was proposed during the period BabyEM was being built. In my opinion vacuum is the only way to get rid of thermal currents and other atmospheric noise in a relatively simple, and probably the only convincing way.

Even if the electronics contain elco's it's possible to nullify the thermal and atmospheric disturbances by measuring apparent thrust in steps of different pressures, like at 1, 0.95, 0.90, 0.85 bar and so on down to a pressure that can still be handled by any pressurised component.


Offline TheTraveller

BabyEM is small enough to have the whole contraption enclosed in a relatively small vacuum chamber. Going on the fact that BabyEM is only a few cm long, the whole contraption seems between 25 and 30 cm long to me. With a bit of redesign it could easily fit in a small chamber which is easier to get than a large one.

Ding tests in a vacuum was proposed during the period BabyEM was being built. In my opinion vacuum is the only way to get rid of thermal currents and other atmospheric noise in a relatively simple, and probably the only convincing way.

Even if the electronics contain elco's it's possible to nullify the thermal and atmospheric disturbances by measuring apparent thrust in steps of different pressures, like at 1, 0.95, 0.90, 0.85 bar and so on down to a pressure that can still be handled by any pressurised component.

Can also change the elco to tants.
"As for me, I am tormented with an everlasting itch for things remote. I love to sail forbidden seas.”
Herman Melville, Moby Dick

Offline Rodal

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WE HAVE RESONANCE!

Attached is TE01x analysis for the Baby EM Drive.

With flat end plates, length resonance can occur anywhere from

the min spacing of:

1) centre of big end plate to centre of small end plate

to max spacing of :

2) outer edge big end plate to outer edge small end plate.

As you can see TE013 generates a length resonance ring just inside the maximal outer edge spacing.

For the Baby EM Drive, there are several resonance modes. Which is driven depends on excitation method, antenna placement and antenna design.

Spreadsheet attached.

I get TE013 for Baby EM Drive with my exact solution at a frequency of 24.34 GHz.  There are many other natural frequencies close by though, so there will be participation from other modes as well.

TE013 is a transverse electric mode shape, therefore the field in the circumferential direction of the Baby EM Drive is electric, while the transverse and the longitudinal fields are magnetic.  It has 3 half-wave patterns along the longitudinal direction, with the strongest fields near the small end of the Baby EM Drive.  Shown below is the Poynting vector field for the Baby EM Drive.

I imagine that it is not a coincidence that TE013 is the natural frequency that matches their excitation frequency.  TE01p has been the preferred mode of excitation of both Shawyer for the Demo and the Flight Thruster, and by Prof. Yang, and it was also the mode shape that gave the highest Force/InputPower for NASA Eagleworks  (see http://emdrive.wiki/Experimental_Results ), so it looks to me that the fellows at Aachen calculated this before they machined Baby EM Drive.  These guys did their homework  ;)
« Last Edit: 06/15/2015 02:30 AM by Rodal »

Offline rfmwguy

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EMDIY project update. Exciter and 8W amp are here. Small bits on their way such as lipo batt pack and rf switch. Planning ahead, I expect the build completed just after july 4th.

Something different, I will try and set up a live broadcast on ustream. Already have 4 live broadcasts now, 24/7, set up for my wife's animal shelter. The live webcams raise awareness for neglected and abused felines. Check them out here: http://carolines-kids.org (I volunteer my time and electronics know-how).

Regardless, I will try and set up a live stream event for test #1. There is a chat mode on the event so I can read questions with abt 1 min delay. Will use ustream rather than youtube which is loaded with trolls.

Thought this might be fun. Will share the private url on nsf for the broadcast as I get closer to test date.

Offline TheTraveller

WE HAVE RESONANCE!

Attached is TE01x analysis for the Baby EM Drive.

With flat end plates, length resonance can occur anywhere from

the min spacing of:

1) centre of big end plate to centre of small end plate

to max spacing of :

2) outer edge big end plate to outer edge small end plate.

As you can see TE013 generates a length resonance ring just inside the maximal outer edge spacing.

For the Baby EM Drive, there are several resonance modes. Which is driven depends on excitation method, antenna placement and antenna design.

Spreadsheet attached.

I get TE013 for Baby EM Drive with my exact solution at a frequency of 24.34 GHz.  There are many other natural frequencies close by though, so there will be participation from other modes as well.

I imagine that it is not a coincidence that TE013 is the natural frequency that matches their excitation frequency.  TE01p has been the preferred mode of excitation of both Shawyer for the Demo and the Flight Thruster, and by Prof. Yang, and it was also the mode shape that gave the highest Force/InputPower for NASA Eagleworks  (see http://emdrive.wiki/Experimental_Results ), so it looks to me that the fellows at Aachen calculated this before they machined Baby EM Drive.  These guys did their homework  ;)

The end plates of the Baby EM Drive are flat, so a lot of close frequencies should obtain resonance. For your 24.34GHz spherical end plate case, the results are attached, which show resonance a bit further away from the side wall but not at the minimal centre to centre end plate spacing.

Would expect thrust to be MUCH greater with spherical and plates as much more (should be all of it) end plate surface area is working at resonance as against a thin ring (very small area) at each end plate.
"As for me, I am tormented with an everlasting itch for things remote. I love to sail forbidden seas.”
Herman Melville, Moby Dick

Offline Rodal

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WE HAVE RESONANCE!

Attached is TE01x analysis for the Baby EM Drive....
What is the numerical value of Shaywer's Design Factor you calculate for the Baby EM Drive, following Shawyer's procedure?
« Last Edit: 06/15/2015 03:12 AM by Rodal »

Offline aero

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With all the fooling I've done with meep recently, I discovered a new trick. I can show different views of slices of a 4-D data set. Here is the closed cavity with the Gaussian drive frequency centered at 2.253 GHz though Meep/Harminv says it resonates at 2.343 GHz. These are all at timestep 1420. What mode is this illustrated.

Shown are big end, center and small end slices "x", and y and z axial slices.
Retired, working interesting problems

Offline TheTraveller

WE HAVE RESONANCE!

Attached is TE01x analysis for the Baby EM Drive....
What is the numerical value of Shaywer's Design Factor you calculate for the Baby EM Drive, following Shawyer's procedure?

Df = 0.7311 @ 24,100,700,000Hz (from their freq meter) @ TE01x as per attached

"As for me, I am tormented with an everlasting itch for things remote. I love to sail forbidden seas.”
Herman Melville, Moby Dick

Offline Abyss

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Here is an analysis using Fourier transform filtering.

http://i.imgur.com/zbP3lxU.png

All time domain signals can be represented in terms of their component frequencies.  In their experiment we aren't interested in the high frequency components because the experimental perturbation isn't rapidly switched, so we can filter them out, which is what I've done.  This leaves the low frequency signal completely intact.  The smallest 'on' range is from frames 18-39, a range of 21.  Thus the cutoff frequency was chosen to be 0.047 (1/21).

The Y axis is displacement because I subtracted the mean.
« Last Edit: 06/15/2015 10:29 AM by Chris Bergin »

Offline deltaMass

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Well, you're Murrikan so I suppose you have to use Imperial units. One day this will change. One centimetre at a time. Except you won't spell it right
:(

Offline deltaMass

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WE HAVE RESONANCE!

Attached is TE01x analysis for the Baby EM Drive.

With flat end plates, length resonance can occur anywhere from

the min spacing of:

1) centre of big end plate to centre of small end plate

to max spacing of :

2) outer edge big end plate to outer edge small end plate.

As you can see TE013 generates a length resonance ring just inside the maximal outer edge spacing.

For the Baby EM Drive, there are several resonance modes. Which is driven depends on excitation method, antenna placement and antenna design.

Spreadsheet attached.
Pretty good for a guy who is being sick for 4 weeks, after less than a week. Congrats!

Offline TheTraveller

WE HAVE RESONANCE!

Attached is TE01x analysis for the Baby EM Drive.

With flat end plates, length resonance can occur anywhere from

the min spacing of:

1) centre of big end plate to centre of small end plate

to max spacing of :

2) outer edge big end plate to outer edge small end plate.

As you can see TE013 generates a length resonance ring just inside the maximal outer edge spacing.

For the Baby EM Drive, there are several resonance modes. Which is driven depends on excitation method, antenna placement and antenna design.

Spreadsheet attached.
Pretty good for a guy who is being sick for 4 weeks, after less than a week. Congrats!

I'm not sick as such. Recovering from surgery. Can still use a laptop for a few hours a day. Did say would post the multi mode version of my EM Drive Calculator. Is good to be able to quickly test 80 modes for resonance.
« Last Edit: 06/15/2015 05:52 AM 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 deltaMass

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Anyone going to confirm my 15% figure?

Offline Abyss

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...Another thing is to do some autocorrelation analysis on the TS.  R has what you need.

I was showing that the human mind is built by Nature to see patterns, many times where there may not be any patterns.  (The face on Mars, trees on Mars, etc.)

...

Focusing on the Movax experiment, they should try to use oil (instead of water) to dampen the vibrations.

If calculate we must, calculate we will.  We can also do autocorrelation and power spectral density with Mathematica:

(I guess we could also try to do a cross-correlation with the on/off signal later on...)

Actually the cross-correlation looks interesting, there is a relatively clear max (magnitude) centered around 0. Interestingly this absolute max is found at a lag of 3 frames (is it 3 minutes ?). Not rock solid statistics but lucky if it was only a coincidence in the absence of any actual correlation.

So Prunesquallor's activation periods averaged cuts seem not that much misleading, there may have a thing going on.

Attached plot :
Horizontal = lag
Vertical = sum (averaged) on all t of activation(t)*data(t+lag) with normalized data and activation +1(on)/-1(off) (0 outside)
This is using the discrete formula for cross-correlation, what I call lag is n in the formula, excitation (on/off) is f and data is g.

Was just going to post this when I saw you did it, I saw a delay of 5 frames though, with a magnitude of -0.167 (normalized) on a 5 frame offset, which is meaningful.  There must have been some kind of measurement error that offset the switching of the device on and off, because there is no way that delay is chance.

Offline TheTraveller

Have found the freq range for the Baby Em Drive operating at TE013

Upper: 25.327GHz - Centre
Lower:  23.927GHz - Outer edge

As the Rf source is narrow band, very little of either end plate area will be in resonance and able to exchange momentum, so thrust will be a very small traction of that predicted by the SPR thrust equation.

Design rule seems to be, if your Rf source has a wide bandwidth and you are using flat end plates, design the frustum so the Rf range runs from resonance at the centre at highest frequency to resonance at the outer edges at the lowest frequency as then you may have a hope to capture more of the mixed frequency energy in the cavity.

For a narrow band Rf source, using flat end plates may be a waste of time as very little of the cavity end plate area will be in resonance. Much better to use spherical end plates as then the entire surface area of the end plates will be in length resonance and able to contribute to thrust generation.

Does anybody know the output bandwidth of a microwave magnetron? If so I will do an analysis of that as against the EW frustum. Yes I do know the energy distribution versus frequency will not be flat, which just adds another element to the analysis task.
« Last Edit: 06/15/2015 06:28 AM 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 TheTraveller

Here is the data for the EW, non dielectric, frustum operating at 2.168GHz as attached.

The only mode with resonance is TM013, in a thin length resonance ring about 40% of the way between the centre and the outer edge. See new chart that plots where a narrow band Rf would resonant between centre and the outer edge. No way to tell if EW excited that mode but even so thrust would be very weak as very little end plate area would be in resonance.
"As for me, I am tormented with an everlasting itch for things remote. I love to sail forbidden seas.”
Herman Melville, Moby Dick

Offline OttO

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For people wanting to look at it another way (in a liquid way  :P) :


General Navier-Stokes-like Momentum and Mass-Energy Equations
We have shown that by starting with general forms of momentum, mass and energy hydrodynamic conservation equations we can arrive at analogous general forms
of momentum and mass-energy equations applicable to electromagnetic flow


http://arxiv.org/abs/1410.6794

Optics of Nonuniformly Moving Media
A moving dielectric appears to light as an effective gravitational field. At low flow velocities the
dielectric acts on light in the same way as a magnetic field acts on a charged matter wave.


http://arxiv.org/abs/physics/9906038


It is another way (by similarity) to obtain the various mechanisms that has been discussed here.

Offline flux_capacitor

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I have a more general question about the evolution of all this research.

According to Shawyer, we have to increase the Q factor up to billions in order to scale the thrust (with the help of superconducting cavities). Hence Shawyer envisioned not only thrusters for spaceprobes and spaceships, but also "lift engines" here on Earth, with -literally speaking- flyings cars and the like around the corner.

If Shawyer is wrong regarding the scale law of thrust vs Q (and the lack of published experimental results of superconducting EmDrives up to now would bolster this pessimistic view), but the EmDrive is still real, would the thrust stay very low even with high power, restricting the applications to space-based thrusters only?

If an alternate model is right, for example Todd's: wavelength attenuation produces thrust in a refractive index gradient, due to an energy density unevenly distributed thanks to a proper asymmetric geometry aka the frustum: the thrust is then maximized while increasing the attenuation, and not increasing the energy stored into the cavity via the Q factor (the "tug of war" between attenuated energy and stored energy).

If this model is right, according to you WarpTech, would the max. thrust be caped well below one gee, or do you think your model could enable lift-engines in Earth gravity field, with enough power on board? (powerful still cheap and light energy source, I'm not speaking of fitting a nuclear power plant in a car…)

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