Author Topic: EM Drive Developments - related to space flight applications - Thread 3  (Read 1878520 times)

Offline deltaMass

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It would be nice to get status updates from the other DIYers listed on the wiki who don't regularly check in here. There are 13 in all. 4 post here, Iulian is gone for good (I think), which leaves 8 not accounted for.

Offline SeeShells

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Theories. They abound and we're at what? Close to a dozen right now? the way I see it each and every one has its good points and bad and if you're here to discover the truth you can't strap yourself to just one. You might be eating your hat.

I have my favorite but that cannot and will not detract or bias me in finding the why. The only real data that is true is mother natures and she trumps and belittles us all, she wrote the book we can barely read.

I've been quite surprised by the simulations in meep and even though meep has it's limits it's enough to allow me to setup several testing criteria to test for different data. One is if this was a normal waveguide or resonant chamber you would expect a stable mode generation and a clean traveling wave locked into Q or traveling down the wave guide. This hasn't been the case. Because of the frustum's variable geometry I see in just a short run for a few cycles in meep mode changes and decays up and down the frustum.

Can anyone explain to me when I see a mode shift in the meep time slices the time it seems to happen... it's within the meep data sample rate. The modes shift from top to bottom or side to side and if actions within the cavity still obey basic laws how can I see a full mode shift top to bottom in less than 1 ns (from sample rate to sample rate which is 1/10th of a cycle?) Light and most actions travels about ~11 inches in 1 ns. I'm so trying to gork opps grok this. I guess I need someone to give me a primmer.

Shell

Same thing happens in dynamic structural response, for example in earthquake analysis or the dynamic response of a rocket during lift-off  https://en.wikipedia.org/wiki/Structural_dynamics#Modal_participation_factor.

Think of the response of a structure to an earhtquake, or the dynamic response of a rocket during the initial lift-off.



The whole concept of "modal response" analysis is a simplification to real response that involves a variety of modes.  For linear response one can describe a so called mode participation factor.

The difference between Meep and a closed-form solution is that Meep is NOT conducting a modal response.  Actually there are no explicit things as "evanescent waves", "travelling waves" or "standing waves", "group velocity" or "phase velocity" in Meep's solution method.  All there is in Meep are fields vs time.  The meaning of the the response has to be analyzed and is not obvious.   Meep is solving Maxwell's equations using the finite difference method.    To put the solution in terms familiar like "modes" for example requires achieving something approaching steady state that has not been achieved in the very short-time response being analyzed (less than 0.01 microseconds as I recall). 

The Meep solution so far should be interpreted as a transient response, not as a steady-state response.
Thanks! That makes so much more sense. Hate it when something doesn't make sense.

Feeling better.

shell

Offline zero123

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I'm not here to defend TT, but I find that a regretful attitude.... :(
 
Whatever experiment TT does, due to his great similarity with what Shawyer did in the past, it will help to assess if Shawyer's experiments hold any value or not.
At least, in contrast with Shawyer, TT promised total transparency on his approach. That will make it much easier to follow the experiment and draw conclusions from it.

So, in that respect TT's experiment remains valuable, regardless of the huge clash of opinion you both have...

I'm looking forward to ALL the experiments, not just a few of them...
Even from the baby EMdrive, we could draw some conclusions that can be useful for future experiments.

I don't see the point to start bickering over experiments that have not taken place yet...?
Good experiments, bad experiments, failures.. you need it all to make progress when you're into uncharted territory...

The thing is, if you read TT's posts carefully it appears that he has already concluded what the outcomes of his experiments will be. This is a very dangerous attitude for an experimenter to have and it is not entirely unreasonable for people to doubt any results even before they come out.

Yes, in principle, data from a well-designed experiment should speak for itself. But in practice, such extreme biases have ways of getting in the way.

Offline ElizabethGreene

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Backward?

That data is based on microwave industry equations and Cullen 15 for the radiation pressure on the end plate bounce Force / momentum transfer per bounce.

The difficulty I have is that by setting f=2.45, P=1, Lambda=c/f, Bigend widest dimension=lambda, smallend widest dimension = lambda/2+0.000001m and plugging that into the Cullin equation I get

BigEnd5.77 x 10-9
SmallEnd1.20 x 10-11

*Math attached.

The force is bigger on the big end by the Cullin Equation you posted.  Try it.

Offline lmbfan

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Given his announced commercial (licensing) relationship with Shawyer and  unwillingness to consider anything that deviates from what is prescribed by Shawyer, it has become apparent that it is a waste of my time to spend any further time discussing anything related to TheTraveller. 

I have also arrived at the conclusion that I cannot trust any experimental claims that TheTraveller may present.

I look forward to the experiments of rfmwguy and SeeShells and hopefully to any further news from NASA Eagleworks and Tajmar.

I know I'm just a bit player in all this, but I have to reluctantly agree with Dr. Rodal here.  I sincerely hope that when TheTraveller turns on his device and it doesn't move (which, despite all of this, I think is the most likely outcome), he has the intellectual honesty to report the results accurately and without bias.  But the degree of blind and continuing adherence to Shawyer's theories and results, without even entertaining the thought that there may be significant errors in them (or even outright dishonesty), has made it more and more difficult to sustain such hope.

The contemptuous attitude towards any who question Shawyer's theory or try to figure out if and where there were experimental errors in Shawyer's results indicates to me that TheTraveller is responding in a primarily emotional mode, where responses to criticisms should, in my view, be primarily rational.  We're all trying to get to the truth here, and responding in such fashion turns this endeavor into an adversarial process, rather than a cooperative one.  TheTraveller is not the only one guilty of contemptuous and/or adversarial posts.  Reposting the same images over and over again is also not helpful.  What is helpful is a thoughtful discourse aimed at resolving whatever misunderstanding has produced the conflicting views.  There is only one truth*, after all.

I also sincerely hope that TheTraveller makes available duplicates of his frustums for further testing as he has previously promised.  If thrust is indeed present, then no one will have to rely on TheTraveller's reports alone. This, for me, is the saving grace.

*As truth relates to reality.  Not trying to get metaphysical here.  ;D

Offline demofsky

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I'm not here to defend TT, but I find that a regretful attitude.... :(
 
Whatever experiment TT does, due to his great similarity with what Shawyer did in the past, it will help to assess if Shawyer's experiments hold any value or not.
At least, in contrast with Shawyer, TT promised total transparency on his approach. That will make it much easier to follow the experiment and draw conclusions from it.

So, in that respect TT's experiment remains valuable, regardless of the huge clash of opinion you both have...

I'm looking forward to ALL the experiments, not just a few of them...
Even from the baby EMdrive, we could draw some conclusions that can be useful for future experiments.

I don't see the point to start bickering over experiments that have not taken place yet...?
Good experiments, bad experiments, failures.. you need it all to make progress when you're into uncharted territory...

The thing is, if you read TT's posts carefully it appears that he has already concluded what the outcomes of his experiments will be. This is a very dangerous attitude for an experimenter to have and it is not entirely unreasonable for people to doubt any results even before they come out.

Yes, in principle, data from a well-designed experiment should speak for itself. But in practice, such extreme biases have ways of getting in the way.

I agree with @FlyBy.  TT's transparency in this whole dialog is something I do respect.  Also, his approach using a control algorithm is very interesting and could be invaluable to other experimenters especially since he promised to share as he has with his spreadsheet.  Finally, he has outlined excellent data capture and at the end of the day that is all that matters.

Biases are important in the interpretation of the data.  The biases to be careful of are those that are hidden.  Everyone knows exactly where TT stands! 

Offline Mulletron

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It doesn't matter anyway what the radiation pressure is at either end. Even if there are unbalanced forces at each end, internal to the frustum, it isn't going to move.

This is central to why everyone (mostly celebrity scientists and the media) is saying this thing violates COM.

I recommend we get rid of any theory that features unbalanced forces at the large/small end and focus on what we recently learned from @Aero and @Rodal that there is a net (and increasing) Poynting vector.
We have a great opportunity to understand what is going on in the near future because we have two very trustworthy people working on independent objective tests (rfmwguy and SeeShells).   It is a very unusual opportunity because (just as we did for a while with Paul March at NASA) both rfmwguy and SeeShells are active in this thread.   Their approach to testing is unbiased and objective.  Unlike what happened with NASA we are under no threat of the communication being interrupted, and unlike what happened with Iulian they are active in the thread and we are under no threat of rfmwguy or SeeShells suddenly stopping their experiments.

PS: coincidentally, I had also been looking to friction as well.  To be explicit: related to the boundary conditions between air and the frustum and between the electromagnetic field and the frustum.

IRT to the PS part at the bottom of your message. I've been reading around the net that apparently an induced electric field due to a time varying magnetic field is non conservative. But then I ask myself.....so what?

http://www.phy.duke.edu/~lee/P54/Notes/edyn.pdf (page 5)
« Last Edit: 08/07/2015 04:13 PM by Mulletron »
Challenge your preconceptions, or they will challenge you. - Velik

Offline Mulletron

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It doesn't matter anyway what the radiation pressure is at either end. Even if there are unbalanced forces at each end, internal to the frustum, it isn't going to move.

This is central to why everyone (mostly celebrity scientists and the media) is saying this thing violates COM.

I recommend we get rid of any theory that features unbalanced forces at the large/small end and focus on what we recently learned from @Aero and @Rodal that there is a net (and increasing) Poynting vector*.

* http://forum.nasaspaceflight.com/index.php?topic=37642.msg1401370#msg1401370

The momentum loss to the internal EM wave is balanced by the momentum gained by the external frustum, so CofM is maintained. Why is that hard to understand? It is a balanced momentum transfer.

Inside the frustum there are 4 momentum reactions:

1) Small end plate bounce of the longer EM wavelength with smaller momentum and smaller opposite but equal Force on the Frustum toward the big end.

2) Large end plate bounce of the shorter EM wavelength with larger momentum and larger opposite but equal Force on the frustum toward the small end.

3) Momentum EM wave gain as the EM wave propagates small end to big end with an opposite but equal momentum Force on the frustum toward the small end. (rocket like effect)

4) Momentum Em wave loss as the EM wave propagates big end to small end with a Force on the frustum toward the small end. (downwind sail like effect)

Shawyer has shown cases 1 and 2 balance out and do not generate any external Force as attached.

What cases 1 and 2 do is to set up the conditions for cases 3 and 4 to exist and transfer EM wave momentum to the frustum.

The lost internal EM wave momentum is balanced by the external frustum's gained momentum, so CofM is conserved as both Shawyer and Prof Yang claimed.

And what about the backward momentum of the magnetron? The frustum and the magnetron are both rigidly attached to the same structure. If this thing were floating in space inside a ship, it would go nowhere.

"The total momentum of a system remains constant provided that no external forces act on the system."

The "system" is the thruster plus ship and power source. How does Shawyer's theory open up the system? Where is the external force acting on the system?
« Last Edit: 08/07/2015 04:28 PM by Mulletron »
Challenge your preconceptions, or they will challenge you. - Velik

Offline ElizabethGreene

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The difficulty I have is that by setting f=2.45, P=1, Lambda=c/f, Bigend widest dimension=lambda, smallend widest dimension = lambda/2+0.000001m and plugging that into the Cullin equation I get
<snip>...
The force is bigger on the big end by the Cullin Equation you posted.  Try it.

Reading my own post makes me see things in a new light.

I've assumed that P is the same on the bigend and the small end.  I should not make that assumption.

P is measured in Watts per square meter.  Given 1000 Watts in the box, a little end of .3m2 and a big end of 1m2 then a crude approximation is Plittle 1000/.3 = 3000 and Pbig of 1000/1 = 1000.

Then you can end up with F_small > F_big if the small end is far from the equivalent waveguide cutoff and Pbig < Psmall

Aside from Conservation of Momentum, what stupid rookie mistake did I make above?  Is Pbig<Psmall realizable in a physical system?

Offline TheTraveller

It doesn't matter anyway what the radiation pressure is at either end. Even if there are unbalanced forces at each end, internal to the frustum, it isn't going to move.

This is central to why everyone (mostly celebrity scientists and the media) is saying this thing violates COM.

I recommend we get rid of any theory that features unbalanced forces at the large/small end and focus on what we recently learned from @Aero and @Rodal that there is a net (and increasing) Poynting vector*.

* http://forum.nasaspaceflight.com/index.php?topic=37642.msg1401370#msg1401370

The momentum loss to the internal EM wave is balanced by the momentum gained by the external frustum, so CofM is maintained. Why is that hard to understand? It is a balanced momentum transfer.

Inside the frustum there are 4 momentum reactions:

1) Small end plate bounce of the longer EM wavelength with smaller momentum and smaller opposite but equal Force on the Frustum toward the big end.

2) Large end plate bounce of the shorter EM wavelength with larger momentum and larger opposite but equal Force on the frustum toward the small end.

3) Momentum EM wave gain as the EM wave propagates small end to big end with an opposite but equal momentum Force on the frustum toward the small end. (rocket like effect)

4) Momentum Em wave loss as the EM wave propagates big end to small end with a Force on the frustum toward the small end. (downwind sail like effect)

Shawyer has shown cases 1 and 2 balance out and do not generate any external Force as attached.

What cases 1 and 2 do is to set up the conditions for cases 3 and 4 to exist and transfer EM wave momentum to the frustum.

The lost internal EM wave momentum is balanced by the external frustum's gained momentum, so CofM is conserved as both Shawyer and Prof Yang claimed.

And what about the backward momentum of the magnetron? The frustum and the magnetron are both rigidly attached to the same structure. If this thing were floating in space inside a ship, it would go nowhere.

"The total momentum of a system remains constant provided that no external forces act on the system."

The "system" is the thruster plus ship and power source. How does Shawyer's theory open up the system? Where is the external force acting on the system?

Try it assuming the Rf energy in the frustum comes from a Rf amp via coax to an antenna inside the frustum.

The ultimate source of the momentum (energy in motion) in the EM wave is the power supply, which is outside the frustum. So power supply energy is converted into Force, which accelerates the frustum.

Draw a box around the power supply, Rf amp and the frustum. Inside the box momentum is conserved as the lost EM wave momentum (which is really just energy in motion) becomes gained frustum momentum (energy in motion). Inside the box energy is conserved as the lost power supply energy is gained by the EMDrive as kinetic energy.
"As for me, I am tormented with an everlasting itch for things remote. I love to sail forbidden seas.
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Offline Flyby

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The thing is, if you read TT's posts carefully it appears that he has already concluded what the outcomes of his experiments will be. This is a very dangerous attitude for an experimenter to have and it is not entirely unreasonable for people to doubt any results even before they come out.

Yes, in principle, data from a well-designed experiment should speak for itself. But in practice, such extreme biases have ways of getting in the way.
Agreed with you that a to heavily biased opinion may result in "seeing what you want to believe".
like...canals on mars, anyone?

But in essence we are all biased inhere.
Biased if the EMdrive works or not, biased if this or that theory might be the right one, if this or the other way to calculate is the correct way to do. We all have our preferred opinions on about everything in this world.

We're all guessing here, nobody knows (yet) what is or might be going on. There are no "objective" criteria. It is all subjective or biased interpretation. Objectivity is an illusion and does not exist.

However, what is most important in scientific research is a persons ability to question his own biased opinions. The ability to stand back and overlook it again and again. Doubting yourself and your test results is what makes great science...

Being biased is an essential step in research as it makes you look for something, but you need to have that ability to constantly revert to a previous position. Once you're no longer questioning things, you become tunnel visioned. Dare i say... narrow minded ?

but we're all biased and nothing wrong with that...  8)
« Last Edit: 08/07/2015 05:13 PM by Flyby »

Offline rfmwguy

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I received an interesting pm from a NSF member and I was able to get his permission to show you a link (and username) to a fulcrum idea he whipped together rather quickly...based on my em vortex pondering:

https://drive.google.com/file/d/0B1djIf10X_KKa0JFNUNQSC05YWs/view?usp=sharing

Note this open-sided frustum design would be interesting as direct reflections wouldn't easily travel towards the source. A slotted waveguide feed might be ideal. Sort of looks like Tajmar's design only shallower launch angle into the frustum...a squirrel-cage fan in reverse when you visualize it.

Thanks @failsafe for the idea...think its rather clever despite your "fast draw" ;) Perhaps a new DIYer might want to give this a shot.

Offline Star One

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I haven't seen this article posted on here yet. This thread gets a mention.

The EM drive energy paradox

http://physicsfromtheedge.blogspot.co.uk/2015/08/the-emdrive-energy-paradox.html?m=1

Offline TheTraveller

I'm not here to defend TT, but I find that a regretful attitude.... :(
 
Whatever experiment TT does, due to his great similarity with what Shawyer did in the past, it will help to assess if Shawyer's experiments hold any value or not.
At least, in contrast with Shawyer, TT promised total transparency on his approach. That will make it much easier to follow the experiment and draw conclusions from it.

So, in that respect TT's experiment remains valuable, regardless of the huge clash of opinion you both have...

I'm looking forward to ALL the experiments, not just a few of them...
Even from the baby EMdrive, we could draw some conclusions that can be useful for future experiments.

I don't see the point to start bickering over experiments that have not taken place yet...?
Good experiments, bad experiments, failures.. you need it all to make progress when you're into uncharted territory...

The thing is, if you read TT's posts carefully it appears that he has already concluded what the outcomes of his experiments will be. This is a very dangerous attitude for an experimenter to have and it is not entirely unreasonable for people to doubt any results even before they come out.

Yes, in principle, data from a well-designed experiment should speak for itself. But in practice, such extreme biases have ways of getting in the way.

I have a very clear expectation.

To observe the totally self contained rotary table accelerate from 0 rpm to at least 120 rpm.

The experiment is designed to replicate and verify Shawyer's rotary table experimental data. If the experimental results are different, then so be it.

Anyone watching the live stream will see the results.

Hard to see how any bias will make the table accelerate from 0 rpm to at least 120 rpm?
"As for me, I am tormented with an everlasting itch for things remote. I love to sail forbidden seas.
Herman Melville, Moby Dick

Offline Giovanni DS

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Anyone watching the live stream will see the results.

Hi, will you allow spectators to experiment and let them access and inspect the setup?

I am not asking for myself, just to know.

Offline TheTraveller

Anyone watching the live stream will see the results.

Hi, will you allow spectators to experiment and let them access and inspect the setup?

I am not asking for myself, just to know.

Sure, no problems. Shall I invite a JP to witness and sign off on the test runs?

Once I have all the bugs worked out, including bugs in the Raspberry 2B (basically 5 modules 1) freq tracking 2) data monitoring 3) data logging and retrieval 4) PC USB interface 5) rotary BlueTooth to PC interface) and PC side software, plan to do the live stream and then do a run at the local uni physics dept. They are very interested in seeing the demo.
« Last Edit: 08/07/2015 05:51 PM 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 SteveD

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I'm not here to defend TT, but I find that a regretful attitude.... :(
 
Whatever experiment TT does, due to his great similarity with what Shawyer did in the past, it will help to assess if Shawyer's experiments hold any value or not.
At least, in contrast with Shawyer, TT promised total transparency on his approach. That will make it much easier to follow the experiment and draw conclusions from it.

So, in that respect TT's experiment remains valuable, regardless of the huge clash of opinion you both have...

I'm looking forward to ALL the experiments, not just a few of them...
Even from the baby EMdrive, we could draw some conclusions that can be useful for future experiments.

I don't see the point to start bickering over experiments that have not taken place yet...?
Good experiments, bad experiments, failures.. you need it all to make progress when you're into uncharted territory...

The thing is, if you read TT's posts carefully it appears that he has already concluded what the outcomes of his experiments will be. This is a very dangerous attitude for an experimenter to have and it is not entirely unreasonable for people to doubt any results even before they come out.

Yes, in principle, data from a well-designed experiment should speak for itself. But in practice, such extreme biases have ways of getting in the way.

Personally, I think he's so sure of the result that I expect, even if the EMDrive is a real thing, that the first test run is going to brick.  My Murphy has a tendency to make a point about hubris.

That said, if he can create a repeatable setup then we can move on from "is this doing anything" to "why is this causing an easily observed effect."  That transition tends to free up funding and resources.

Offline Rodal

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END OF EM DRIVE THREAD NUMBER 3

This is probably a good place to end this thread.

Thread 4!
http://forum.nasaspaceflight.com/index.php?topic=38203.0

Farewell Thread 3, and we thank you.

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