Author Topic: EM Drive Developments - related to space flight applications - Thread 3  (Read 1803860 times)

Offline SeeShells

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@rfmwguy or any that care to answer.

Everyone (almost) believes that the highest Q will produce the largest results, that's not quite true, that means there is evidence (Chinese tests) that a slight off tuned resonance or sweeping through a resonance mode can produce higher thrust values.

I'm asking because it will help develop my thinking on the next step of MW control and testing. I'm grasping here for thoughts and ideas of why that might be true.

Shell

EDIT: readability
« Last Edit: 07/08/2015 02:09 PM by SeeShells »

Offline Rodal

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@rfmwguy or any that care to answer.

Everyone (almost) believes that the highest Q will produce the largest results. That means and there is evidence out there (Chinese tests) that this might not be true, that a slight off tuned resonance or sweeping through a resonance mode can produce higher thrust values.

I'm asking because it will help develop my thinking on the next step of MW control and testing. I'm grasping here for thoughts and ideas of why that might be true.

Shell

It is a very confusing picture.
Prof. Tajmar will be presenting results at the AIAA in a few days that, it is my understanding will show very low force/PowerInput in vacuum: less than 50 microNewtons for several hundreds of watts input power, at a very low Q (less than 100).

NASA's results show a very erratic relationship with Q, certainly not monotonic: there are NASA tests showing larger thrust output with lower Q.

Only NASA and Tajmar have run EM Drive tests in vacuum.

Roger Shawyer's tests are notorious for not having reported a single test in vacuum ever, even though he has been reporting on tests longer than anyone else.  Shawyer's lack of reporting a single test in vacuum maybe telling us something about the true (much lower) performance of the EM Drive in vacuum.

Shawyer's theoretically extremely high Q superconducting drive has run into development problems for the reasons discussed in his paper: Doppler shift, resulting in lower thrust/InputPower, as he reported in his 2014 paper.

Shawyer's, McCulloch's and Notsosureofit's thrust expressions are all proportional to Q. 
If my understanding is correct, Todd's thrust expression is not proportional to Q.

« Last Edit: 07/08/2015 02:16 PM by Rodal »

Offline SeeShells

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@rfmwguy or any that care to answer.

Everyone (almost) believes that the highest Q will produce the largest results. That means and there is evidence out there (Chinese tests) that this might not be true, that a slight off tuned resonance or sweeping through a resonance mode can produce higher thrust values.

I'm asking because it will help develop my thinking on the next step of MW control and testing. I'm grasping here for thoughts and ideas of why that might be true.

Shell

It is a very confusing picture.
Prof. Tajmar will be presenting results at the AIAA in a few days that, it is my understanding will show very low force/PowerInput in vacuum: less than 50 microNewtons for several hundreds of watts input power, at a very low Q (less than 100).

NASA's results show a very erratic relationship with Q, certainly not monotonic: there are NASA tests showing larger thrust output with lower Q.

Only NASA and Tajmar have run EM Drive tests in vacuum.

Roger Shawyer's tests are notorious for not having reported a single test in vacuum ever, even though he has been reporting on tests longer than anyone else.  Shawyer's lack of reporting a single test in vacuum maybe telling us something about the true (much lower) performance of the EM Drive in vacuum.

Shawyer's theoretically extremely high Q superconducting drive has run into development problems for the reasons discussed in his paper: Doppler shift, resulting in lower thrust/InputPower, as he reported in his 2014 paper.

Shawyer's, McCulloch's and Notsosureofit's thrust expressions are all proportional to Q. 
If my understanding is correct, Todd's thrust expression is not proportional to Q.


Have the first publishing.

I love it when things can pop out of nothing. (Interesting read, with some good flags).
Observation of the Dynamical Casimir Effect in a
Superconducting Circuit
http://arxiv.org/pdf/1105.4714v1.pdf

I've pretty much found the same thing in Q. The vacuum test while showing lower thrust is a great piece of data (hate seeing it as it adds to the complexity) and it might not be the killer we think. Upon seeing the lower values (you know less heat dissipation in a vacuum, right?, think high modified Q through thermal expansion) it might not be as bad as we think. I think I would have pumped the cavity with some air and tested it in a vacuum and that was not done.

Thanks for summarizing the conundrum.

Shell

Offline rfmwguy

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@rfmwguy or any that care to answer.

Everyone (almost) believes that the highest Q will produce the largest results, that's not quite true, that means there is evidence (Chinese tests) that a slight off tuned resonance or sweeping through a resonance mode can produce higher thrust values.

I'm asking because it will help develop my thinking on the next step of MW control and testing. I'm grasping here for thoughts and ideas of why that might be true.

Shell

EDIT: readability
FWIW, High Q and pure signals are where I've always tried to be, but this thing is different somehow. Before putting time/money at signal purity, CW and highest Q possible, I'm just trying to test a basic concept. There is a good chance that I'll stop there if I have null results and pass the hat to someone else. First, we take baby steps with whatever we have, then tweak it...mainly to test other's claims. So my advice is take a swing at it without over-engineering/over-thinking it. The smallest amount of positive results can lead to modifications, such as top-hat tuning, reduced power/cleaner signal, etc.

Offline SeeShells

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@rfmwguy or any that care to answer.

Everyone (almost) believes that the highest Q will produce the largest results, that's not quite true, that means there is evidence (Chinese tests) that a slight off tuned resonance or sweeping through a resonance mode can produce higher thrust values.

I'm asking because it will help develop my thinking on the next step of MW control and testing. I'm grasping here for thoughts and ideas of why that might be true.

Shell

EDIT: readability
FWIW, High Q and pure signals are where I've always tried to be, but this thing is different somehow. Before putting time/money at signal purity, CW and highest Q possible, I'm just trying to test a basic concept. There is a good chance that I'll stop there if I have null results and pass the hat to someone else. First, we take baby steps with whatever we have, then tweak it...mainly to test other's claims. So my advice is take a swing at it without over-engineering/over-thinking it. The smallest amount of positive results can lead to modifications, such as top-hat tuning, reduced power/cleaner signal, etc.
You're right but I'm thinking after this very basic run. I sometimes feel that I'm pounding a nail with a large rock this first test, when I need a small hammer.

Offline Possibles

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Well dang it thank you!
One of my favorite books was https://en.wikipedia.org/wiki/The_Mote_in_God's_Eye
They talked about "The Crazy Eddie Drive" and sometimes I begin to feel this is "The Crazy DYI Drive". :D

I have no doubt with the great minds here and those sitting in silence until a time comes to speak up, it will be solved.

Shell
[/quote]

DYI Drive? ... "Do Yourself In Drive" perhaps? I certainly feel like it that's the case from my side... (-;

Offline TheTraveller

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All the various items are covered by a transparent cover to give very low and symmetrical wind resistance.
Are you going to have a vacuum inside the transparent cover?
If the answer is no, the initially static air has its own inertia and will resist being moved and rotated, it will be moved by the no-slip condition at the boundary with the rotating solid objects, and dragged by its viscosity mainly at the boundary layer.  This will still produce fluid mechanics effects, including vortices and aerodynamic drag (what you call "wind resistance) inside the cover until a steady-state is achieved.

I'm well aware of what you mention which is still better than allowing the cavity to rotate uncovered and experience full on wind resistance.
"As for me, I am tormented with an everlasting itch for things remote. I love to sail forbidden seas.”
Herman Melville, Moby Dick

Offline DrBagelBites

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@rfmwguy or any that care to answer.

Everyone (almost) believes that the highest Q will produce the largest results, that's not quite true, that means there is evidence (Chinese tests) that a slight off tuned resonance or sweeping through a resonance mode can produce higher thrust values.

I'm asking because it will help develop my thinking on the next step of MW control and testing. I'm grasping here for thoughts and ideas of why that might be true.

Shell

EDIT: readability

Have we run a Meep simulation of the input signal being an oscillating signal from one frequency to another and back down again? I'm not even sure Meep can do that.

Perhaps, creating something like a square wave pattern would be ideal instead of sinusoidal.
« Last Edit: 07/08/2015 03:08 PM by DrBagelBites »

Offline Prunesquallor

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@ Shell.

I feel the same way. Although I have no resources to physically check things out myself nor your experience as an engineer, everything I have read and investigated brings me to the conclusion that there is something we are missing here. There are too many seemingly related threads that point to there being really something special to discover. You can almost taste it. And from my experience this doesnt tend to happen with bad ideas. Something is definitely going on.

It's just that finding that damn thing is the difficult bit.
Well dang it thank you!
One of my favorite books was https://en.wikipedia.org/wiki/The_Mote_in_God's_Eye
They talked about "The Crazy Eddie Drive" and sometimes I begin to feel this is "The Crazy DYI Drive". :D

I have no doubt with the great minds here and those sitting in silence until a time comes to speak up, it will be solved.

Shell

 "...any Motie who comes to believe a solution is possible is labeled as a "Crazy Eddie" and deemed insane".

Hmmmmm...
Retired, yet... not

Offline DrBagelBites

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Duty cycle on magnetrons...a new power supply would be needed AND figure on 50% reduced RF power (CW) output, or about 400W from an 800W magnetron. Realistically, most of us will have to stick with off the shelf stuff. I suggest that independent experimenters who want to go in that direction should do so, but be aware of the costs associated with custom power supplies and tubes. Here's what I suggest to those about to embark on a more expensive experiment (unless your wealthy ;)):

1) prove you've gotten some results (video the build and test - avoid vaporware/unsubstantiated claims)
2) publicly commit to open source disclosure (unless I am mistaken, this forum is non-commercial)
3) describe where you want to take it next in detail (maybe ask for equip donations)
4) set up a gofundme or similar site and link to it (with the mods permission, that is)

We have a unique opportunity to shove this thing along or simply prove its not possible. While I'd love to prove its real, I'd also feel accomplishment by showing the alternative, as we all should.

As a side note, if I see the slightest positive results when I fire this thing up (prior to the live video stream) I plan to get a 3rd party in to film it as well. Could be a local media outlet or my old colleague who works at NASA Glenn nearby. drbagelbites could get his school's CCTV station there, shell could twist an arm or two in her local media.

Look, this thing could be revolutionary, but if not properly announced, demonstrated and verified, its just another free energy, perpetual motion machine in the public's eye. Experimenters need to think carefully how its presented and it should be done so in a professional manner.    /end soapbox ramble.

Maybe it is just me, personally, but I would like to be, statistically speaking, at least 95% confident I have something before I start crying wolf.

I only have one chance to have a first impression, and I want to be pretty sure it works before I give that up.

As you said, if not properly announced, demonstrated, and verified it's just another fluke. So, until I can convince myself, I will not be able to convince others.

-I

For comparison, the CERN guys' threshold was five sigma before announcing Higgs.

If only I had billions of dollars, then this would be a done deal. ;)

Offline Rodal

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@rfmwguy or any that care to answer.

Everyone (almost) believes that the highest Q will produce the largest results, that's not quite true, that means there is evidence (Chinese tests) that a slight off tuned resonance or sweeping through a resonance mode can produce higher thrust values.

I'm asking because it will help develop my thinking on the next step of MW control and testing. I'm grasping here for thoughts and ideas of why that might be true.

Shell

EDIT: readability

Have we run a Meep simulation of the input signal being an oscillating signal from one frequency to another and back down again? I'm not even sure Meep can do that.

Perhaps, creating something like a square wave pattern would be ideal.
yes Meep can do that.  Meep is an open source program.  Most users write their own constitutive equations and routines, (certainly when they publish papers), instead of using it as a black box. 

At the moment we are at a post-processing stage rather than a pre-processing stage: interpreting the data:

1) Initial Meep runs were output with each frame having different Max Min.  This lead to images showing fractals which have no physical significance as the fractals were the numerical artifact of very  low values (close to zero) showing the numerical fractality of the FD grid and not a physical phenomenon.  The images also showed different colors for the zero region outside the EM Drive, for the same artificial reason.  This was addressed by having all the frames have the same Max Min.  This enables the "movies" to show values close to zero as being close to zero.  This also eliminated the artifact of different colors outside the EM Drive geometry.

2) At that point we still had only images, no numerical values, and only for the electromagnetic fields in Cartesian coordinates.  The next advance was to output csv files, that everybody has access to: everybody can view these files to ascertain the numerical values in Meep units.  We plotted those values as Contour Plots and 3D Plots.  The value of this was not just that they look "prettier".  The value is that we showed the numerical values and we have contours associated with numerical values in increasing colors.  The htoutput (spelling?) images on the other hand have no numerical values and the colors repeat themselves, which is confusing as one cannot ascertain the intensity of the field with a given color.

3) The next stage was to take the numerical csv data that everybody has access to, to show the Poynting vector field.  I used Mathematica to perform these computations, based on the csv files output from Meep.  Notice that these are vector field plots.  These vector plots have much more significance than the contour plots of Cartesian scalar components of the 6 electromagnetic fields, as the Poynting vector gives power surface density= Power/CrossSectionalArea vectors.  The Poynting vector away from the antenna was shown to not average to zero (as it does for standing waves with the RF feed OFF).  This is due to the RF feed ON from the antenna, which produces time-varying travelling waves (that Zeng and Fan show to "run continuously from a propagating through evanescent as they get closer to the apex of the cone ") instead of frozen in space standing waves.

4) The next stage was to plot the time fluctuation of the Poynting vector.  We have done this for just two cycles.  We are in the process of evaluating the Meep units into SI units and to ascertain its numerical growth for those two cycles.  Obviously two cycles is not enough. After that is done we will need to look at several more cycles to ascertain the evolution of the Poynting vector field through time.

5) Thank you for your idea. we should do that kind of analysis.  We also have to take a look at other geometries for different builds: "Shell's Warp",  the behavior of different antenna types and locations, and we have to analyze, for example the "pointy cone" geometries that I analyzed with standing waves in a paper weeks ago.
« Last Edit: 07/08/2015 03:47 PM by Rodal »

Offline DrBagelBites

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@rfmwguy or any that care to answer.

Everyone (almost) believes that the highest Q will produce the largest results, that's not quite true, that means there is evidence (Chinese tests) that a slight off tuned resonance or sweeping through a resonance mode can produce higher thrust values.

I'm asking because it will help develop my thinking on the next step of MW control and testing. I'm grasping here for thoughts and ideas of why that might be true.

Shell

EDIT: readability

Have we run a Meep simulation of the input signal being an oscillating signal from one frequency to another and back down again? I'm not even sure Meep can do that.

Perhaps, creating something like a square wave pattern would be ideal.
yes Meep can do that.  Meep is an open source program.  Most users write their own constitutive equations and routines, (certainly when they publish papers), instead of using it as a black box. 

At the moment we are at a post-processing stage rather than a pre-processing stage: interpreting the data:

1) Initial Meep runs were output with each frame having different Max Min.  This lead to images showing fractals which have no physical significance as the fractals were the numerical artifact of very  low values (close to zero) showing the numerical fractality of the FD grid and not a physical phenomenon.  This was addressed by having all the frames have the same Max Min.  This enables the "movies" to show values close to zero as being close to zero.  This also eliminated the artifact of different colors outside the EM Drive geometry.

2) At that point we still had only images, no numerical values, and only for the electromagnetic fields in Cartesian coordinates.  The next advance was to output csv files, that everybody has access to: everybody can view these files to ascertain the numerical values in Meep units.  We plotted those values as Contour Plots and 3D Plots.  The value of this was not just that they look "prettier".  The value is that we showed the numerical values and we have contours associated with numerical values in increasing colors.  The htoutput images on the other hand have no numerical values and the colors repeat themselves, which is confusing as one cannot ascertain the intensity of the field with a given color.

3) The next stage was to take the numerical csv data that everybody has access to, to show the Poynting vector field.  Notice that these are vector field plots.  These vector plots have much more significance than the contour plots of Cartesian scalar components of the 6 electromagnetic fields, as the Poynting vector gives power surface density= Power/CrossSectionalArea vectors.  The Poynting vector was shown to not average to zero (as it does for standing waves with the RF feed OFF).  This is due to the RF feed ON from the antenna, which produces time-varying travelling waves (that Zeng and Fan show to "run continuously from a propagating through evanescent as they get closer to the apex of the cone ") instead of frozen in space standing waves.

4) The next stage was to plot the time fluctuation of the Poynting vector.  We have done this for just two cycles.  We are in the process of evaluating the Meep units into SI units and to ascertain its numerical growth for those two cycles.  Obviously two cycles is not enough. After that is done we will need to look at several more cycles to ascertain the evolution of the Poynting vector field through time.

Thank you for the summary! Definitely good to have a nice list of what has been going on.

 I've been trying to learn Meep in my free time to try and contribute something to you guys as well. Clearly, nothing yet.

Thanks again!

-I

Offline rfmwguy

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@rfmwguy or any that care to answer.

Everyone (almost) believes that the highest Q will produce the largest results, that's not quite true, that means there is evidence (Chinese tests) that a slight off tuned resonance or sweeping through a resonance mode can produce higher thrust values.

I'm asking because it will help develop my thinking on the next step of MW control and testing. I'm grasping here for thoughts and ideas of why that might be true.

Shell

EDIT: readability

Have we run a Meep simulation of the input signal being an oscillating signal from one frequency to another and back down again? I'm not even sure Meep can do that.

Perhaps, creating something like a square wave pattern would be ideal instead of sinusoidal.
A Magnetron naturally pulses and sprays all sorts of byproducts around 2.45 GHz. If I were to take another step, it would be to reduce power and spurious to see if the "junk" helps or hurts the cause.

Offline Rodal

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A Magnetron naturally pulses and sprays all sorts of byproducts around 2.45 GHz. If I were to take another step, it would be to reduce power and spurious to see if the "junk" helps or hurts the cause.

What is your guesstimate for the date of your first test ?
« Last Edit: 07/08/2015 03:48 PM by Rodal »

Offline graybeardsyseng

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@rfmwguy or any that care to answer.

Everyone (almost) believes that the highest Q will produce the largest results, that's not quite true, that means there is evidence (Chinese tests) that a slight off tuned resonance or sweeping through a resonance mode can produce higher thrust values.

I'm asking because it will help develop my thinking on the next step of MW control and testing. I'm grasping here for thoughts and ideas of why that might be true.

Shell

EDIT: readability
FWIW, High Q and pure signals are where I've always tried to be, but this thing is different somehow. Before putting time/money at signal purity, CW and highest Q possible, I'm just trying to test a basic concept. There is a good chance that I'll stop there if I have null results and pass the hat to someone else. First, we take baby steps with whatever we have, then tweak it...mainly to test other's claims. So my advice is take a swing at it without over-engineering/over-thinking it. The smallest amount of positive results can lead to modifications, such as top-hat tuning, reduced power/cleaner signal, etc.
You're right but I'm thinking after this very basic run. I sometimes feel that I'm pounding a nail with a large rock this first test, when I need a small hammer.

Shell - have you made any progress in getting a VNA from local hams?   I think a VNA may be a very useful piece of test gear, particular as the EMDrive locks in to freq/modulation and/or changes mode; particular if the data can be captured at a high enough data rate.    Just FYI, here are a couple of links to a (more or less) affordable 2 port VNA.

http://miniradiosolutions.com/   -the mini VNA tiny will go to 3Ghz

http://www.hamradio.com/detail.cfm?pid=H0-013596  HRO has them for about $575.   

**Context Switch**
"Mote in God's Eye" - one of the books I re-read every few years.   Maybe the best science fiction ever - perhaps excluding Heinlein.  I still want to be Sir Kevin Renner when I grow up.

Herman-W5HLP
EMdrive - finally - microwaves are good for something other than heating ramen noodles and leftover pizza ;-)

Offline WarpTech

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I see that Shawyer's "latest paper"  8)  contains a specification of 2/3 N/W. This corresponds to a breakeven velocity of 3 m/s, mechanically an easily attainable value. Can we therefore expect Shawyer to branch out into the power generation field in the near future?
Just a little follow-up here to answer a question that some may be asking: "What is a reasonable value of Newtons/Watt such that overunity could be achieved with a rotary device in a terrestrial lab?"

It's a mechanical limitation. An aggressive spec. is something like 1,000 gee with a 1 metre radius arm. That's about 1,000 rpm and a tangential velocity of about 100 m/s. That in turn calls for a minimum k-value of
0.02 N/W.
Keep that figure in mind.
@kdhilliard has been kind enough to point out to me that the correct figure here should be 0.01 N/W, because the power breakeven velocity is what's important from a practical point of view. To recap:
Energy breakeven velocity = 2/k
Power breakeven velocity = 1/k

The power breakeven proof is not difficult:
Pout = d/dt(0.5 m v2) = m v a = Pin when v := vp
So vp = Pin / (m a) = Pin / F = Pin / (k Pin) = 1/k
QED

Your equation for Pout is wrong.

Pout = d/dt(0.5 m v2) = m v a + 0.5 v2 dm/dt

When you leave out dm/dt, it results in your over-unity paradox. In order to have acceleration, dm/dt cannot be zero. The kinetic energy gained can never exceed the change in mass, dm * c2.
Todd

Offline BL

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For rfvp in response to Post #3648

First, you responded SPECIFICALLY to EACH of the points that I made in my post.  I am sure you realize how unusual THAT is on generic internet forums.  Thank you.

You may be surprised that I agree with each of your comments.  Each and every problem that I mentioned CAN be addressed as you noted.   In theory.

On the other hand (remember, we are dealing with my OPINION here), because of their implications, your explanations make MY points pretty effectively.

The generic DIY-er can easily and cheaply make or have made a frustum projected to resonate at 2.45 GHz.  Can he/she design and build the circuitry necessary to phase lock it to an external reference or injection lock it to the frustum?  Or mechanically lock the frustum to the magnetron?  When hooked to the frustum, which of the many resonant frequencies does it lock to?  How does the DIY-er know?  If no thrust is detected with the first mode, how does he test the other resonant modes?  If the magnetron is injection locked to the frustum how does the experimenter tune the magnetron outside the bandwidth of the thruster to determine if the thrust is related to resonance or an artifact of the test apparatus?

Put a tuning slug on the frustum.  How does that affect the Q and mode(s) of resonance?  How does the DIY-er know?   When tuning, what is the feedback to the person doing the tuning, so that he knows what is going on? 

Don’t get me wrong; I am VERY supportive of DIY-ers who have the initiative to try to ‘make it happen’; I am just pessimistic as to their chances of success using a free-running magnetron and not as sanguine as you about the triviality of ‘just tune the frustum and allow the magnetron to injection lock to it ‘ solutions to the known problems.  I am aware that magnetrons HAVE been used, reportedly with success.  I am also aware that one reason that the reported success of the magnetrons is greeted with so much skepticism is that with a magnetron it is difficult to know your test environment with precision.  The good news is that if the magnetron is hooked to the frustum and unambiguous thrust appears and disappears in concert with the magnetron being turned on and off, victory can be declared, and we can turn the data over to the theorists to figure out why.  Of course the theorists would probably like to know such details as which mode was being excited, the exact frequency that was responsible for the thrust, the Q at that mode, the power being injected within the bandwidth of the frustum and so on, but that could probably be determined post hoc.  The bad news would occur if thrust DIDN’T occur.  Especially if the frustum had a relatively high Q.  Would the principle be falsified?  Operating in the wrong mode?  Spectral output of the magnetron places little or no energy into the bandwidth of the frustum?  What next?

As for risking the destruction of solid state amps with VSWR, how is the magnetron going to cope with a return loss close to 0 dBm?  Rack mounted broadband TWTA’s with a couple hundred watts output are available for rent and they are guaranteed to operate into any load without damage (I’d use an external circulator just for fun though.). 

I know that one of the reasons that the DIY’ers are doing this is just for the sheer fun of designing, building, and testing their own, personal frustum, but given the time, expense, and other hassles of building a tunable frustum and getting the magnetron to injection lock, accompanied by the difficulty in determining just what is happening when all this tuning is going on makes a TWTA/solid state amp driven by a precision sig gen—where you KNOW what is going on--sound much more attractive to ME.  YMMV.

As for SeeShells and the other builders:  I don’t know where you are geographically or what access you have to microwave stuff in your ‘day job’, but if you are in the Northern VA/DC/Suburban MD area I MAY be able to get you access to such desirable widgets as a vector network analyzer, precision sig gens (including vector signal generators that in addition to the standard am/fm/cw allow you to generate signals with an arbitrary output spectrum), power meters, spectrum analyzers, and power amplifiers in the 100+ watt range.   I am retired, but there is some possibility, considering the implications of real microwave thrusters, that my old employer would give me access, on a not to interfere basis, to any or all of the above.  I haven’t asked.  Yet.

Offline WarpTech

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Shawyer's, McCulloch's and Notsosureofit's thrust expressions are all proportional to Q. 
If my understanding is correct, Todd's thrust expression is not proportional to Q.
...

Instantaneous thrust is proportional to Q, but not steady state thrust. In my table, I show the required Delta-Energy. If you divide that by the input energy Pin*t, you have the unloaded Q required to reach that energy state. Once there is thrust however, Q will drop and thrust will drop off, until it recharges again.
Todd

Offline zen-in

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Your equation for Pout is wrong.

Pout = d/dt(0.5 m v2) = m v a + 0.5 v2 dm/dt

When you leave out dm/dt, it results in your over-unity paradox. In order to have acceleration, dm/dt cannot be zero. The kinetic energy gained can never exceed the change in mass, dm * c2.
Todd

While I understand the physics I would like to offer an example that seems to violate this.   An electrodynamic tether uses solar electrical power to energize a long cable that is normal to the geomagnetic field.   DC power flows through the tether and then back through space with the help of charged particles.  The Lorentz force on the tether, F = B X I * L causes the tether to accelerate.   Considering the geomagnetic field to be constant for sake of argument and also if the current is constant, the acceleration of the tether will be constant.   The geomagnetic field strength does vary around the Earth but we will ignore that.   The geomagnetic field strength also doesn't change when the observer is moving.    And of course dM/dt = 0.    How is this apparent paradox resolved?

Offline SeeShells

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@ Shell.

It's just that finding that damn thing is the difficult bit.

Shell

 "...any Motie who comes to believe a solution is possible is labeled as a "Crazy Eddie" and deemed insane".

Hmmmmm...
And there you have It! DYIers=Crazy Eddies you are one fart smeller... oops I mean one smart feller.

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