Author Topic: EM Drive Developments - related to space flight applications - Thread 3  (Read 1804263 times)

Offline deltaMass

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It will at the very least make an attractive pendant if miniaturised  ;)

Online Rodal

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...
I doubt it will fix it. The "rotation" looks more like simply reflections bouncing side to side, around a circle. 3 antenna will just have 3 overlapping sets of random reflections. We shall see...
Todd
Here I present the Poynting vector field for the final 14 time slices.  It would be fun if somebody makes this into a movie

The truncated cone Yang/Shell is shown with the small base at the top and the big base at the bottom

As Todd said, energy is bouncing from side to side, and as Shell said it is also rotating, but it is interesting how it is concentrated mostly towards the small end.
« Last Edit: 08/05/2015 11:28 PM by Rodal »

Online SeeShells

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...
I doubt it will fix it. The "rotation" looks more like simply reflections bouncing side to side, around a circle. 3 antenna will just have 3 overlapping sets of random reflections. We shall see...
Todd
Here I present the Poynting vector field for the final 14 time slices.  It would be fun if somebody makes this into a movie

The truncated cone Yang/Shell is shown with the small base at the top and the big base at the bottom
My neighbor found out my mom passed away and ask me over for Steak and Maine lobster. I'm not turning it down! BBL and I'll do the gif movie of the poynting pointing.

Shell

Offline TheUberOverLord

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Food for thought or just plain "Too wild and crazy" for consideration as being in the mix for possible EM Drive theory?

Especially when dealing with things like the Quantum field theory and the Casimir effect

The mystery of particle generations

While I personally have not seen any facts which back this up. I assume that the Casimir effect can take place without the need of using a vacuum using normal ranges of atmospheric pressures. Maybe others here can state if that's a yes or no? If not, why not?

Edit: Typo

Don
« Last Edit: 08/06/2015 01:59 AM by TheUberOverLord »
EM Drive builders can use these free Interfaces to show their tests live using any IP Cameras in websites Click for live demo examples

Online SeeShells

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Different kind of Poynting for Shell Yang TE012 snub ant lower right Db
Shell
« Last Edit: 08/06/2015 02:18 AM by SeeShells »

Offline ElizabethGreene

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I assume that the Casimir effect can take place without the need of using a vacuum using normal ranges of atmospheric pressures.

I believe you can.  The shims in a set of automobile feeler gauges http://amzn.to/1K4yy85 will glue together with a surprising degree of force if you degrease them first.

I understand that machinists have problems with flats sticking to surface plates from this effect

Offline rfcavity

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What mesh grid size are you guys using for those meep sims? It seems like more of a stepped cylinder than a tapered cavity, or is that intended?

Online SeeShells

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What mesh grid size are you guys using for those meep sims? It seems like more of a stepped cylinder than a tapered cavity, or is that intended?
Originally intended to be like the Yang but calculations we took from come of the drawings we're not quite right. So we are running a frustum with a 6 degree from centerline, with a snub antenna @2.45 GHz in the bottom section on the sidewall we are trying to activate a TE012 mode.

Online aero

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What mesh grid size are you guys using for those meep sims? It seems like more of a stepped cylinder than a tapered cavity, or is that intended?
The lattice is 0.2747255683428571 meters long, that includes the length of the cavity and boundaries. Resolution is 250, so the grid is 0.274/250 meters/pixel ~ 1.1 mm/cell. The image resolution is probably not that dense making it appear more granular than it is. 
Retired, working interesting problems

Offline lmbfan

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There's almost certainly a much, much better way to do this, but here's a basic perforated cube.  Only the +/- x and +/- y walls have holes, the top and bottom plates are solid, but this should be good enough for illustration purposes.  The walls are ~2" X 1" X 1", holes are 1/16" diameter on a 3/16" spacing. Angle of +/- y walls are 6.159 degrees from horizontal.  All these values are variable.  If you increase or decrease the size of the walls, you'll need to put more or less values into the hacky kludges that I used to loop.  If anyone can figure out how to add a second loop, the program can be made many lines shorter.  Using a range() type function for the kludges would be commendable too.  I tried, but looping in Guile is... not very intuitive.  Give me python, or even C/C++/Java any day.

This is just the geometry.  I tried popping this into Aero's meep file, but the pictures didn't look right.  Hopefully someone who understands what they are doing with EM sources can get this going with a proper source for Shell's needs.

Online meberbs

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I'll be the first to point out that the folks here have probably had quite enough of me discussing CoE and over-unity. But to Bae...

I had the same thought. The situation is indeed similar. He is asking us to believe that thrust is proportional to the number of bounces, which is directly related to the Q. So he also has a P*Q factor in his thrust equation. And the obvious question is: how can it be that a cavity which is being pumped steady-state with input power P can yield a force that depends on P*Q? How can that be sustainable for seconds and minutes? It appears that one's extracting more than goes in. 

I confess to being uncertain about this. I saw his experiment where he got thrust that was indeed 2*P*Q/c. The saving grace might well be that photon mirrors only become efficient as the mirror velocity with respect to the light source approaches c. By this logic, he is only sipping at each beam, and despite the fact that multiple reflections are simultaneously in play (which intensifies the beam of course) he is only taking a small fraction out of each individual beam.

But that's an unsatisfactory explanation too, because one could engineer around it. Probably only a mathematical argument could settle it for me.

I haven't seen any documentation on Bae's design, but it sounds like you are talking about a situation where a laser is reflecting between a spacecraft and a mirror presumably located on a more massive object (such as the moon). I have thought about that type of system before, and eventually figured out how it can be consistent with conservation laws. The key is that when a photon reflects off something twice the photon's momentum is transferred, but this only corresponds to a tiny fraction of the photon's energy. This means the photon is barely redshifted and can continue transferring nearly the same momentum each time until: the mirror accelerates enough to cause large redshift, the photon is absorbed by a mirror which converts the energy to heat rather than directed kinetic energy, or the photon misses the reflector.

Since I was curious about the conservation of energy for a single reflection at 0 velocity (when normally equations give 0 doppler shift), I worked out the expected doppler shift. This was based off conservation of momentum and energy, keeping around terms that are normally neglected in doppler shift, since the momentum transfer to objects is negligible in most applications.

the result is:

v2/v1 = sqrt(a^2 + 4*a +1)-a-1, where  a=m*c^2/(h*v1)
where v2 is the new frequency, v1 is the starting frequency, m is the mass of the mirror that the photon reflects off, h and c are the usual constants.

To get an idea of how little energy is transferred in this case, for a photon at 3 GHz, and a mirror mass of only 1e-35 kg, the ratio is 0.999997. Any actual physical mirror with reasonable mass would result in an immeasurably small doppler shift even for much higher frequencies. Repeated reflection just means you get to convert more of the photons energy into the desired form (kinetic energy of your craft) before the rest gets lost in some way.

On a more EM drive related note, photon drive amplification from reflections against test chamber walls was one of my first guesses at possible sources of the EM drive thrust.

Offline deltaMass

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What mesh grid size are you guys using for those meep sims? It seems like more of a stepped cylinder than a tapered cavity, or is that intended?
The lattice is 0.2747255683428571 meters long
Oh please.

Offline deltaMass

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I'll be the first to point out that the folks here have probably had quite enough of me discussing CoE and over-unity. But to Bae...

I had the same thought. The situation is indeed similar. He is asking us to believe that thrust is proportional to the number of bounces, which is directly related to the Q. So he also has a P*Q factor in his thrust equation. And the obvious question is: how can it be that a cavity which is being pumped steady-state with input power P can yield a force that depends on P*Q? How can that be sustainable for seconds and minutes? It appears that one's extracting more than goes in. 

I confess to being uncertain about this. I saw his experiment where he got thrust that was indeed 2*P*Q/c. The saving grace might well be that photon mirrors only become efficient as the mirror velocity with respect to the light source approaches c. By this logic, he is only sipping at each beam, and despite the fact that multiple reflections are simultaneously in play (which intensifies the beam of course) he is only taking a small fraction out of each individual beam.

But that's an unsatisfactory explanation too, because one could engineer around it. Probably only a mathematical argument could settle it for me.

I haven't seen any documentation on Bae's design, but it sounds like you are talking about a situation where a laser is reflecting between a spacecraft and a mirror presumably located on a more massive object (such as the moon). I have thought about that type of system before, and eventually figured out how it can be consistent with conservation laws. The key is that when a photon reflects off something twice the photon's momentum is transferred, but this only corresponds to a tiny fraction of the photon's energy. This means the photon is barely redshifted and can continue transferring nearly the same momentum each time until: the mirror accelerates enough to cause large redshift, the photon is absorbed by a mirror which converts the energy to heat rather than directed kinetic energy, or the photon misses the reflector.

Since I was curious about the conservation of energy for a single reflection at 0 velocity (when normally equations give 0 doppler shift), I worked out the expected doppler shift. This was based off conservation of momentum and energy, keeping around terms that are normally neglected in doppler shift, since the momentum transfer to objects is negligible in most applications.

the result is:

v2/v1 = sqrt(a^2 + 4*a +1)-a-1, where  a=m*c^2/(h*v1)
where v2 is the new frequency, v1 is the starting frequency, m is the mass of the mirror that the photon reflects off, h and c are the usual constants.

To get an idea of how little energy is transferred in this case, for a photon at 3 GHz, and a mirror mass of only 1e-35 kg, the ratio is 0.999997. Any actual physical mirror with reasonable mass would result in an immeasurably small doppler shift even for much higher frequencies. Repeated reflection just means you get to convert more of the photons energy into the desired form (kinetic energy of your craft) before the rest gets lost in some way.

On a more EM drive related note, photon drive amplification from reflections against test chamber walls was one of my first guesses at possible sources of the EM drive thrust.
Bravo. That's exactly what I'm pointing at, and you expressed it very well.

Now, things start to get interesting when we start considering beamers for interstellar   flights. Now Doppler under SR comes in and the maths isn't as simple as you might have imagined:
http://physics.stackexchange.com/questions/162512/relativistic-beamed-photon-propulsion

Offline TheTraveller

...The key is that when a photon reflects off something twice the photon's momentum is transferred, but this only corresponds to a tiny fraction of the photon's energy. This means the photon is barely redshifted and can continue transferring nearly the same momentum each time until: the mirror accelerates enough to cause large redshift, the photon is absorbed by a mirror which converts the energy to heat rather than directed kinetic energy, or the photon misses the reflector.

Since I was curious about the conservation of energy for a single reflection at 0 velocity (when normally equations give 0 doppler shift), I worked out the expected doppler shift. This was based off conservation of momentum and energy, keeping around terms that are normally neglected in doppler shift, since the momentum transfer to objects is negligible in most applications.

the result is:

v2/v1 = sqrt(a^2 + 4*a +1)-a-1, where  a=m*c^2/(h*v1)
where v2 is the new frequency, v1 is the starting frequency, m is the mass of the mirror that the photon reflects off, h and c are the usual constants.

To get an idea of how little energy is transferred in this case, for a photon at 3 GHz, and a mirror mass of only 1e-35 kg, the ratio is 0.999997. Any actual physical mirror with reasonable mass would result in an immeasurably small doppler shift even for much higher frequencies.

Repeated reflection just means you get to convert more of the photons energy into the desired form (kinetic energy of your craft) before the rest gets lost in some way. bolding added

On a more EM drive related note, photon drive amplification from reflections against test chamber walls was one of my first guesses at possible sources of the EM drive thrust.

Nice work.

Clearly explains why EMDrive generated Force scales with Q and why a high Q EMDrive can deliver much more Force than can a photon rocket.

In an EMDrive ....... Q Rules
« Last Edit: 08/06/2015 07:46 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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v2/v1 = sqrt(a^2 + 4*a +1)-a-1, where  a=m*c^2/(h*v1)
where v2 is the new frequency, v1 is the starting frequency, m is the mass of the mirror that the photon reflects off, h and c are the usual constants.
The formula is fine when a=0, because then v2/v1=0 as expected.
But when a >1 (the macroscopic case we have here), v2/v1 >1 also, which seems to make no sense.
« Last Edit: 08/06/2015 08:12 AM by deltaMass »

Offline rfmwguy

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Interesting article linked by our reddit pals:

https://hacked.com/emgate-wars-continue-publication-peer-reviewed-emdrive-paper/

Imo, their emdrive thread is getting much better with more serious pro and con discussions like nsf. Congrats to them an us here for serious but fun discussions which (usually) rise above typical public forums loaded with Qs of less than 50 (insert l where it belongs)..

Offline Star One

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Indeed interesting article. It seems as if the EM drive is now getting a marginally better response in articles like this. Unfortunately it will probably see years of so called wars until a conclusion appears one way or the other.

Online SeeShells

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What mesh grid size are you guys using for those meep sims? It seems like more of a stepped cylinder than a tapered cavity, or is that intended?
The lattice is 0.2747255683428571 meters long
Oh please.
Simply "A Drive By Pasting". :)

Online SeeShells

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Indeed interesting article. It seems as if the EM drive is now getting a marginally better response in articles like this. Unfortunately it will probably see years of so called wars until a conclusion appears one way or the other.
Even if someone makes a EM Drive and flies it up the tailpipes of other theories it will be controversial, it will take years to settle down. Nature of the beast.

Shell

Online SeeShells

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It's funny how evening with a burnt piece of meat, some shellfish, good company, frothy efference (cold of course) can make someone right with the world again.

Today I'm presure washing down the section of the shop clearing it out from dust and all the gunk that collects from years of just being a storage area and putting up air dampeners (plastic sheets dropped from the ceiling) in preparation to start setting up the test rig. I wish I still had my clean room ~1600 sq ft to do this in, but we'll make do with this and make it as clean and quiet (EM) and vibration free as I can. I even had to rebuild my old pressure washer, so may little things to do. ;) But I'm having fun!!!

Shell

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