Author Topic: EM Drive Developments - related to space flight applications - Thread 9  (Read 1800698 times)

Offline WarpTech

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At least the Q is almost equal and cannot be the reason for using the propagated cutoff rule.

What about comparing to the truncated frustum where the highest current density is "on" the SD end plate, not the side walls? That would be more compliant with Shawyer's advice. I think, if we're going to dissipate power asymmetrically, it should be on the end plate, not the side walls, so the flux that is escaping has the vector in the right direction.

Offline X_RaY

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Some pages ago I have posted some early results of two different frustum geometries to compare the Q of both.
https://forum.nasaspaceflight.com/index.php?topic=41732.msg1624968#msg1624968

...

At least the Q is almost equal and cannot be the reason for using the propagated cutoff rule.

Hi X-Ray,

Thank you very much for the detailed simulation analysis!  However, I'm a bit curious as to how you came to your final conclusion.

If I'm reading your results correctly, the truncated frustum had ~4% higher Ql and Qu.  If maximizing Q truly maximizes thrust, then I would assert that your analysis lends credence to the "propagated cutoff rule" rather than refute it.  Getting an extra ~4% "thrust" and simultaneously reducing the total mass of the frustum seems like a pretty good engineering optimization....  assuming "thrust" can be shown as proportional to Q.

Seems like this latest simulation data might offer a glimpse into how Shawyer came up with his "rule of thumb" for frustum design/construction:  ~4% improvement in Q.

Ql_truncated/Ql_cone = 37630/36071 = 104.3%
Qu_truncated/Qu_cone = 75260/72142 = 104.3%
As you can see in the first two results the situation differs from calculation to calculate. The reason is slightly different mesh size and coupling factors. QL=f/δf --> QU= 2*QL  This simple calculation only holds for impedance matched situations(curve hits the central point in the complex plane, in this case Z50 Ω +j0Ω), otherwise the calculation gets more complicated.


There are better ways to increase the Q, especially since the differences as shown seems to be a numerical issues with the FEA.
« Last Edit: 01/06/2017 09:34 am by X_RaY »

Offline X_RaY

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...

At least the Q is almost equal and cannot be the reason for using the propagated cutoff rule.

What about comparing to the truncated frustum where the highest current density is "on" the SD end plate, not the side walls? That would be more compliant with Shawyer's advice. I think, if we're going to dissipate power asymmetrically, it should be on the end plate, not the side walls, so the flux that is escaping has the vector in the right direction.
The small end is slightly above cutoff 151.15mm instead of 149.3mm
I let the cone angle be exactly the same.
TT stated the currents should be minimized at the endplate.

https://forum.nasaspaceflight.com/index.php?topic=41732.msg1624685#msg1624685
« Last Edit: 01/05/2017 08:35 pm by X_RaY »

Offline WarpTech

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...

At least the Q is almost equal and cannot be the reason for using the propagated cutoff rule.

What about comparing to the truncated frustum where the highest current density is "on" the SD end plate, not the side walls? That would be more compliant with Shawyer's advice. I think, if we're going to dissipate power asymmetrically, it should be on the end plate, not the side walls, so the flux that is escaping has the vector in the right direction.
The small end is slightly above cutoff 151.15mm instead of 149.3mm
I let the cone angle exact constant.
TT stated the currents should be minimized at the endplate.

https://forum.nasaspaceflight.com/index.php?topic=41732.msg1624685#msg1624685

Yea, I disagree. If the big end is leading when it's accelerating, then we want the power dissipation "on" the SD end plate.

Offline Monomorphic

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As you can see in the first two results the situation differs from calculation to calculate. The reason is slightly different mesh size and coupling factors.

Don't forget to include the spherical end-plate frustum with Q of 111,454. That is a pretty significant increase.
« Last Edit: 01/05/2017 08:33 pm by Monomorphic »

Offline X_RaY

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As you can see in the first two results the situation differs from calculation to calculate. The reason is slightly different mesh size and coupling factors.

Don't forget to include the spherical end-plate frustum with Q of 111,454. That is a pretty significant increase.
Again, at the moment I don't believe in this Q values based on calculations with HOBF. I get freaky inconclusive results when using it.

EDIT
This is the same frustum as used for the Q compare but using HOBF and fine mesh. Instead of natural possible QL~36000, i get 207000 loaded Q! ???
« Last Edit: 01/05/2017 09:16 pm by X_RaY »

Offline X_RaY

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...

At least the Q is almost equal and cannot be the reason for using the propagated cutoff rule.

What about comparing to the truncated frustum where the highest current density is "on" the SD end plate, not the side walls? That would be more compliant with Shawyer's advice. I think, if we're going to dissipate power asymmetrically, it should be on the end plate, not the side walls, so the flux that is escaping has the vector in the right direction.
The small end is slightly above cutoff 151.15mm instead of 149.3mm
I let the cone angle exact constant.
TT stated the currents should be minimized at the endplate.

https://forum.nasaspaceflight.com/index.php?topic=41732.msg1624685#msg1624685

Yea, I disagree. If the big end is leading when it's accelerating, then we want the power dissipation "on" the SD end plate.
why at the end plate now instead of the "small end" at all?

I don't know if the shown design produces thrust at all. I don't know if one will show more thrust than the other design. The goal was to find out what happens to the Q-factor when one plate is below the cutoff rule.
« Last Edit: 01/05/2017 09:07 pm by X_RaY »

Offline mwvp

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So the mass I've been looking for in order to locate a mass current for the gravitomagnetic equations...(so far effective mass of photons in resonators and waveguide, in materials, photons in a box contributing to overall mass of the box...etc) but one I hadn't considered is (to me the wiser choice now) is the center of mass of a counter-propagating two photon system.

Also apply this in the context of a partial standing wave, and the concept is definitely clicking.

A partial-standing, partial propagating wave would imply a mass-flow (momentum), wouldn't it?

Consider electric-rocket efficiency. Electrically-accelerating (pushing against) a big mass slower, rather than a large mass faster is more efficient, as long as you don't consider propellant-mass in the equation.

How better to improve the efficiency of a photon-rocket than make light heavier and slower using a resonant cavity coupled to a dispersive structure? If you accelerate at a rate approaching the group-velocity of the waves leaving the structure, Doppler-shift approaches 0. All energy converted from radiation to acceleration, ideally. And you measure a static electric & magnetic field. Sort of like a charged particle?

Offline WarpTech

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...

At least the Q is almost equal and cannot be the reason for using the propagated cutoff rule.

What about comparing to the truncated frustum where the highest current density is "on" the SD end plate, not the side walls? That would be more compliant with Shawyer's advice. I think, if we're going to dissipate power asymmetrically, it should be on the end plate, not the side walls, so the flux that is escaping has the vector in the right direction.
The small end is slightly above cutoff 151.15mm instead of 149.3mm
I let the cone angle exact constant.
TT stated the currents should be minimized at the endplate.

https://forum.nasaspaceflight.com/index.php?topic=41732.msg1624685#msg1624685

Yea, I disagree. If the big end is leading when it's accelerating, then we want the power dissipation "on" the SD end plate.
why at the end plate now instead of the "small end" at all?

I don't know if the shown design produces thrust at all. I don't know if one will show more thrust than the other design. The goal was to find out what happens to the Q-factor when one plate is below the cutoff rule.

Because this is comparing 2 frustums where "both" have the power dissipation in the side walls, and your result is that they are almost identical Q values. If we want to see a significant difference in Q, we need to compare two frustums that do NOT both have dissipation on the side walls. One would be on the side walls and the truncated one on the end plate. Think of the small end plate as a partially reflective mirror at one end of a MASER. This is the "output" end of the resonator, and we want the output to be as collimated as possible. I for one would like to know the difference in Q values. It might actually be higher in that configuration.
« Last Edit: 01/05/2017 09:15 pm by WarpTech »

Offline Rodal

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As you can see in the first two results the situation differs from calculation to calculate. The reason is slightly different mesh size and coupling factors.

Don't forget to include the spherical end-plate frustum with Q of 111,454. That is a pretty significant increase.
Again, at the moment I don't believe in this Q values based on calculations with HOBF. I get freaky inconclusive results when using it.

EDIT
This is the same frustum as used for the Q compare but using HOBF and fine mesh. Instead of natural possible QL~36000, i get 207000 loaded Q! ???
Can EmPro calculate Q?
If yes can you check the results with EmPro?

Offline WarpTech

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Because this is comparing 2 frustums where "both" have the power dissipation in the side walls, and your result is that they are almost identical Q values. If we want to see a significant difference in Q, we need to compare two frustums that do NOT both have dissipation on the side walls. One would be on the side walls and the truncated one on the end plate. Think of the small end plate as a partially reflective mirror at one end of a MASER. This is the "output" end of the resonator, and we want the output to be as collimated as possible. I for one would like to know the difference in Q values. It might actually be higher in that configuration.
I could make the frustum even shorter to trigger this pattern at the end plate, should be interesting to get this data too :) Whatever this means for any thrust generation.
It will take a while.. .

I'm working on that, on several fronts. Thank you! We should be getting some definitive, verifiable "theory" soon.

Offline X_RaY

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As you can see in the first two results the situation differs from calculation to calculate. The reason is slightly different mesh size and coupling factors.

Don't forget to include the spherical end-plate frustum with Q of 111,454. That is a pretty significant increase.
Again, at the moment I don't believe in this Q values based on calculations with HOBF. I get freaky inconclusive results when using it.

EDIT
This is the same frustum as used for the Q compare but using HOBF and fine mesh. Instead of natural possible QL~36000, i get 207000 loaded Q! ???
Can EmPro calculate Q?
If yes can you check the results with EmPro?
Yes, and much easier, it's scheduled after holidays.
Cant say when exactly I have time then to do this.
I will let you know.

Offline Monomorphic

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Yes, and much easier, it's scheduled after holidays.
Cant say when exactly I have time then to do this.
I will let you know.

I see there is a free trial version, but one has to apply for it. Do you know what the licensing fees are?

Offline rfmwguy

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So the mass I've been looking for in order to locate a mass current for the gravitomagnetic equations...(so far effective mass of photons in resonators and waveguide, in materials, photons in a box contributing to overall mass of the box...etc) but one I hadn't considered is (to me the wiser choice now) is the center of mass of a counter-propagating two photon system.

Also apply this in the context of a partial standing wave, and the concept is definitely clicking.
Good find. Perhaps this explains why Paul M suggests emdrive performance is enhanced when drive signal freq is slightly off cavity resonance...a condition which should create partial standing waves...which are directional. I might visualize the partial standing wave being able to travel in either direction dependent upon whether the drive freq is above or below resonance peak...which corresponds to deflection forces both forwards and backwards in relation to small and large endplates...which just gave me a brain cramp ;)

Rfmwguy, that idea of yours just triggered my memory. For a long time, I was wondering what unforeseen effect the magnetron experiments may have had, that would not easily (at least not automatically) be replicated in solid state systems.

One possibly large effect will be the particular combination of phase-shifted AM and FM. The magnetron has 100% AM modulation depth at 50 (60) Hz, due to the single diode power supply. However it also has some FM, as evident by the splatter spectra that people had posted here last year. What is interesting however, is that the FM is to a large extent due to magnetron-internal thermal effects, therefore it is phase delayed compared to the AM because of thermal time constants.

What so far nobody seems to have tested with solid state systems is such an AM+FM signal. To maximize the effect, it would need a modulation signal source with separate sine and cosine outputs (I and Q), with I being applied to the frequency control of the RF VCO (working as frequency modulator) and with Q being applied to the gain control of a variable gain amplifier (working as amplitude modulator).

This would create a signal that goes up in frequency (through the center) while at its maximal amplitude and that goes down in frequency while the amplitude is minimal, thereby working like an "unidirectional on average" upwards sweep signal (or a downward sweep if you swap the signal generator polarity). If I'm not mistaken, this may result in a net unidirectional travelling wave like pattern in the resonator.

We may have had that pattern almost forever with the magnetron experiments and nobody realizing its potential siginficance. And then, precision solid state experiments get done with extremely stable signals, and report null results!
Thanks. Good thoughts. If I use my visual, non-mathematical imagination, I would speculate a traveling wave (which carries momentum) may hit a terminus at one end or the other...and impart momentum.

Creating a traveling wave would require frequency sweeping over a narrow band to "send" the traveling wave in one direction or the other and probably should be off center like Paul M has said before.

In addition, a high peak power (pulsed) would be needed to impart the maximum amount of momentum towards the terminus. So, if you "sweep" the cavity, the traveling wave should, in theory, move one way or the other.

Therefore, a pulsed VCO type signal should always be present, which in the case of a magnetron, is there.

The critical point I would speculate (as this is nothing but speculation) is the pulse should be timed to occur at the end of the "ringing" of the initial pulse, however many micro or picoseconds that is...or, it could be additive, I do not know.

So, this thought experiment is setting up very high peak power traveling wave towards one end of the cavity or the other. My thoughts are towards the small end as the traveling wave may gain additional amplitude (?) as it moves into a cutoff region. It won't gain speed, it must gain something else...possibly momentum.

The caveat here is the RF source is in the same frame of reference and should not allow asymmetrical momentum in one direction unless we can somehow invoke the outside world and make it an open system. This is where I hit a brick wall...where would asymmetrical momentum be from? External fields or the "vacuum".

Sorry, I have no answers.
« Last Edit: 01/05/2017 10:57 pm by rfmwguy »

Offline FattyLumpkin

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Does anyone have the dimensions and frequency for this build? Can they share them?  FL  BTW I know this says NSF1701_A but Dave says he doesn't know.
« Last Edit: 01/05/2017 11:02 pm by FattyLumpkin »

Offline Monomorphic

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Again, at the moment I don't believe in this Q values based on calculations with HOBF. I get freaky inconclusive results when using it.

EDIT
This is the same frustum as used for the Q compare but using HOBF and fine mesh. Instead of natural possible QL~36000, i get 207000 loaded Q! ???

I will rerun it without higher-order basis functions (HOBFs) and with mesh set to fine: 13,346 metallic triangles
« Last Edit: 01/05/2017 11:17 pm by Monomorphic »

Offline Monomorphic

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Does anyone have the dimensions and frequency for this build? Can they share them?  FL

That's rfmwguy's NSF1701A. TE013 at ~2.83Ghz. Dave's frustum was designed to operate at 2.45Ghz, but I did a sweep and found TE013 at 2.83. It was a strong signal for that mode, so I took note of it and posted it here.
« Last Edit: 01/05/2017 11:09 pm by Monomorphic »

Offline WarpTech

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...
The caveat here is the RF source is in the same frame of reference and should not allow asymmetrical momentum in one direction unless we can somehow invoke the outside world and make it an open system. This is where I hit a brick wall...where would asymmetrical momentum be from? External fields or the "vacuum".

Sorry, I have no answers.

To quote Dr. Woodward. "Push when it's heavy, pull when it's light." In this case, the antenna emits a "heavy" wave, and what is reflected back to the antenna is a "lighter" wave. If that is how it works, then there is no need to interact with anything external. The CM will ratchet forward, in one direction.

Offline WarpTech

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Does anyone have the dimensions and frequency for this build? Can they share them?  FL

That's rfmwguy's NSF1701A. TE013 at ~2.83Ghz.

We know. What are the dimensions please? Dave's data is not in the wiki.
« Last Edit: 01/05/2017 11:09 pm by WarpTech »

Offline Monomorphic

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Does anyone have the dimensions and frequency for this build? Can they share them?  FL

That's rfmwguy's NSF1701A. TE013 at ~2.83Ghz.

We know. What are the dimensions please? Dave's data is not in the wiki.

This is what was posted elsewhere and what I was given:

ds = 6.25"
ld = 10.0"
height = 8.175"

« Last Edit: 01/05/2017 11:29 pm by Monomorphic »

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