Author Topic: EM Drive Developments - related to space flight applications - Thread 3  (Read 1879520 times)

Offline Slyver

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@SeeShells
I don’t know if you are still having doubts about your current frustum design. If I don’t read for a couple days it takes me a week to catch up, so your feelings may have completely changed since I last read about your frustrations.

Regardless, I would like for you to know, I for one am very excited to see your experimental results exactly as they have been outlined. Your current frustum design may give us valuable information. One can not know until the experiment has been run and the data collected and analyzed what the optimal configuration is for an unknown effect, regardless of simulations (that may very well be leaving out the most important variables). Your set up allows for different antenna designs/placements and different cavity lengths with a solid testing platform eliminating (or reducing below noise level) most air thermal effects* and external EM coupling.

After the first series of tests, you can then run another (otherwise identical) test group on a similar frustum, changing only the cone half angle. The experience gained from building the first should make building a second a breeze.  I expect data from all these different experiments should give EXCELLENT information to help narrow the focus of theory efforts.  Who knows, your smaller cone angle could give the largest thrust.  Wouldn’t that be a kick.

*We don’t know what effect air may have. Perforation may be deleterious to the “real” effect (if it exists).
« Last Edit: 08/04/2015 01:51 PM by Slyver »

Offline Rodal

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...
An interesting effect for sure.

My point was what Todd was claiming files in the face of how radiation pressure works, which is there will be no radiation pressure on a surface, from a EM wave, that is orthogonal to a reflecting surface, which is what Shawyer claims and was backed up by the peer reviewers.
You are failing to distinguish between the physical problem of a confined wave and a free wave.

To fix your ideas: think of the difference between fluid flow inside a venturi pipe (you clearly have pressure on the inner surfaces of the pipe) and the flow of a water jet tangent to a rigid surface, with the other surface of the fluid jet having a free surface (the free surface of the fluid jet is unconfined, and therefore its pressure is not higher than ambient pressure).

The problem of radiation pressure of a free wave orthogonal to a surface ("solar sail") and tangent to the surface is different from the problem at hand.  You have to analyze the problem mathematically and solve the boundary conditions of the problem: you have a photon gas inside the frustum.  The inner surfaces of the frustrum confine the electromagnetic fields inside the frustum hence there is pressure against all internal surfaces.

« Last Edit: 08/04/2015 02:11 PM by Rodal »

Offline SeeShells

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@SeaShells
I don’t know if you are still having doubts about your current frustum design. If I don’t read for a couple days it takes me a week to catch up, so your feelings may have completely changed since I last read about your frustrations.

Regardless, I would like for you to know, I for one am very excited to see your experimental results exactly as they have been outlined. Your current frustum design may give us valuable information. One can not know until the experiment has been run and the data collected and analyzed what the optimal configuration is for an unknown effect, regardless of simulations (that may very well be leaving out the most important variables). Your set up allows for different antenna designs/placements and different cavity lengths with a solid testing platform eliminating (or reducing below noise level) most air thermal effects* and external EM coupling.

After the first series of tests, you can then run another (otherwise identical) test group on a similar frustum, changing only the cone half angle. The experience gained from building the first should make building a second a breeze.  I expect data from all these different experiments should give EXCELLENT information to help narrow the focus of theory efforts.  Who knows, your smaller cone angle could give the largest thrust.  Wouldn’t that be a kick.

*We don’t know what effect air may have. Perforation may be deleterious to the “real” effect (if it exists).
I will run it as a testbed setup and publish the figures. It is the start of serious testing and yes other shapes and forms and configurations of EMDrives will also be tested. The data needs to be filled in from the bottom to the top on one test stand that can do both pressure and acceleration over time.

I'm getting my other O2 free copper sheet today... yea...
Updated: 08/04/2015 9:48 A.M. Eastern Time
On Vehicle for Delivery Today
Scheduled Delivery:
Tuesday, 08/04/2015, By End of Day

Just got a Dell laptop that I sniped on Ebay for a "ridiculous" price and found out the charger doesn't work but had enough charge to see it does work. Have another charger on order and when it gets here I'll multi-partition it with Win8, Ubuntu and Windows XP, want to try running http://www.petr-lorenz.com/emgine/   and it doesn't run on win7 and above. plus several others that just run on Ubuntu.

Shell

Offline SeeShells

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An interesting effect for sure.

My point was what Todd was claiming files in the face of how radiation pressure works, which is there will be no radiation pressure on a surface, from a EM wave, that is orthogonal to a reflecting surface, which is what Shawyer claims and was backed up by the peer reviewers.
You are failing to distinguish between the physical problem of a confined wave and a free wave.

To fix your ideas: think of the difference between fluid flow inside a venturi pipe (you clearly have pressure on the inner surfaces of the pipe) and the flow of a water jet tangent to a rigid surface, with the other surface of the fluid jet having a free surface.

The problem of radiation pressure of a free wave orthogonal to a surface ("solar sail") and tangent to the surface is different from the problem at hand.  You have to analyze the problem mathematically and solve the boundary conditions of the problem: you have a photon gas inside the frustum.
You lost me here. Where do you see a fluid carrying pipe? It's a tapered fiber optic with a light source traveling through it set in a medium with cells.

A photon gas... yes and a EM wave... yes. The electromagnetic wave is made up from lots of photons.  Wave-particle duality of photons applies to electrons as well.

All these fifty years of conscious brooding have brought me no nearer to the answer to the
question, 'What are light quanta?' Nowadays every Tom, Dick and Harry thinks he knows it,
but he is mistaken. (Albert Einstein, 1954)

 

Offline daj24

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Did anyone see the "Candorville" comic strip for today?  An EM drive reference.
"You'll be a witness to that game of chance in the sky. You know we've got to win" D. Fagen

Offline SeeShells

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An interesting effect for sure.

My point was what Todd was claiming files in the face of how radiation pressure works, which is there will be no radiation pressure on a surface, from a EM wave, that is orthogonal to a reflecting surface, which is what Shawyer claims and was backed up by the peer reviewers.
You are failing to distinguish between the physical problem of a confined wave and a free wave.

To fix your ideas: think of the difference between fluid flow inside a venturi pipe (you clearly have pressure on the inner surfaces of the pipe) and the flow of a water jet tangent to a rigid surface, with the other surface of the fluid jet having a free surface (the free surface of the fluid jet is unconfined, and therefore its pressure is not higher than ambient pressure).

The problem of radiation pressure of a free wave orthogonal to a surface ("solar sail") and tangent to the surface is different from the problem at hand.  You have to analyze the problem mathematically and solve the boundary conditions of the problem: you have a photon gas inside the frustum.  The inner surfaces of the frustrum confine the electromagnetic fields inside the frustum hence there is pressure against all internal surfaces.
On the confined wave as in creating a high Q mode within the frustum. In every sim I've seen the modes shift internally and decay, that decay is into a evanescent wave.

Is this not true?

Offline Rodal

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A gas is a compressible fluid and as such describable by fluid dynamics, just a different constitutive law.  Different fluids have different constitutive laws.

Offline rfmwguy

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Thermal tests done including 5 minute run at 30% power, which is what I'll use for fulcrum test. What I learned: Matching into frustum is good, magnetron ran at temperatures well below 200°C. Still had minor arcing, corrected it with full teardown and replacement of Db with mesh only, no copper clad. IOW, frustum is now all mesh except for Ds where magnetron is mounted. There was no arcing on Ds throughout any thermal testing. Plasma focused on Db, interestingly enough diagonally across from radome, not directly across axially.

Here's the video, time to do yard work, oh joy:

Offline SeeShells

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A gas is a compressible fluid and as such describable by fluid dynamics, just a different constitutive law.  Different fluids have different constitutive laws.
True.

What this video shows is light waves consisting of photons traveling as waves down a long conical fiber optic cable (right to left) that causes them to frequency shift as they loose resonance and then decay into traveling evanescent waves outside of the fiber optic walls.  These evanescent waves carry momentum and spin components that are orthogonal to the direction of wave propagation. Those components of momentum and spin outside of the walls of the fiber optic cable effect the fluid inducing movement along the length of the optic cable.

I have a conical frustum analogous to the tapered fiber optic that induces the same actions in the frustum. The collapsing modes and waves decay into evanescents just like the fiber optic. My question would be what happens to that spin and momentum of that high Q wave as it collapses into the end or sidewalls of the cavity? Mediums are different but it's still photons and waves. 

Offline TheTraveller

REF and Quote... https://en.wikipedia.org/wiki/Evanescent_wave

Shell

Inside a solid copper EMDrive, designed to follow Shawyer's dimensional recommendations, there are no Evanescent waves as the small end operates above cutoff.

This is not to say do not experiment with creating internal frustum dimensional, mode and external frequency situations that will create internal Evanescent waves at the small end.

What the SPR advise says is that in their experience, operation of the small end at or below cutoff and creating Evanescent waves will result in no significant resonance and no significant Force generation.

Your mileage may vary.
« Last Edit: 08/04/2015 03:42 PM by TheTraveller »
"As for me, I am tormented with an everlasting itch for things remote. I love to sail forbidden seas.”
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Offline SeeShells

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Thermal tests done including 5 minute run at 30% power, which is what I'll use for fulcrum test. What I learned: Matching into frustum is good, magnetron ran at temperatures well below 200°C. Still had minor arcing, corrected it with full teardown and replacement of Db with mesh only, no copper clad. IOW, frustum is now all mesh except for Ds where magnetron is mounted. There was no arcing on Ds throughout any thermal testing. Plasma focused on Db, interestingly enough diagonally across from radome, not directly across axially.

Here's the video, time to do yard work, oh joy:

Great test! I noticed as your cavity heated up the arcing diminished. Do you think it was due to the magnetron stabilizing? Your cavity pretty much negates thermal expansion with the screen (nice idea).

I just want to hear you sing "Never, Never Gonna Give Ya Up"  by Barry White. Nice voice for narrating.

Shell

Offline TheTraveller

We are calculating frequencies based on different geometrical dimensions.

There is only 1 definition of length in a resonant frustum.

That is the physical distance between the big and small end plates that will fit X number of 1/2 spherical waves at the effective frustum guide wavelength.

Anything else is not resonance.
"As for me, I am tormented with an everlasting itch for things remote. I love to sail forbidden seas.”
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Offline SeeShells

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REF and Quote... https://en.wikipedia.org/wiki/Evanescent_wave

Shell

Inside a solid copper EMDrive, designed to follow Shawyer's dimensional recommendations, there are no Evanescent waves as the small end operates above cutoff.

This is not to say do not experiment with creating internal frustum dimensional, mode and external frequency situations that will create internal Evanescent waves at the small end.

What the SPR advise says is that in their experience, operation of the small end at or below cutoff and creating Evanescent waves will result in no significant resonance and no significant Force generation.

Your mileage may vary.
Interesting TT because the tapered cavity induces by its shape wave and mode decay. https://en.wikipedia.org/wiki/Evanescent_wave#/media/File:Electron_density_wave_-_plasmon_excitations.png
The traveling and mode decay are evanescent waves.

 

Offline TheTraveller

REF and Quote... https://en.wikipedia.org/wiki/Evanescent_wave

Shell

Inside a solid copper EMDrive, designed to follow Shawyer's dimensional recommendations, there are no Evanescent waves as the small end operates above cutoff.

This is not to say do not experiment with creating internal frustum dimensional, mode and external frequency situations that will create internal Evanescent waves at the small end.

What the SPR advise says is that in their experience, operation of the small end at or below cutoff and creating Evanescent waves will result in no significant resonance and no significant Force generation.

Your mileage may vary.
Interesting TT because the tapered cavity induces by its shape wave and mode decay. https://en.wikipedia.org/wiki/Evanescent_wave#/media/File:Electron_density_wave_-_plasmon_excitations.png
The traveling and mode decay are evanescent waves.

 

There are no dielectrics inside a SPR frustum. Nor are there any Evanescent (dying) waves inside a SPR frustum. If there were such energy loss waves inside the frustum, they would quickly kill Q as they would add to wall eddy current losses.

Maybe explain how it would be possible to get a frustum Q of 50k and higher if there were Evanescent waves inside the frustum?

To be quite honest, I suggest there is a lot of beat up here about mode and mode shape. If you excite in ANY TE mode, ALL the H field energy is moving back and forth between the end plates. The coloured pictures are nice but I fail to see how they can or will influence Force generation.

Don't see mode mentioned in:

F = (2 P Q Df) / c.

Do you?

I do see that that different TE modes may be easier to excite than others and easier to couple an antenna to while generating very low phase distortion between the resonant wave and the excitation antenna.
« Last Edit: 08/04/2015 04:02 PM by TheTraveller »
"As for me, I am tormented with an everlasting itch for things remote. I love to sail forbidden seas.”
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Offline RonM

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Thermal tests done including 5 minute run at 30% power, which is what I'll use for fulcrum test. What I learned: Matching into frustum is good, magnetron ran at temperatures well below 200°C. Still had minor arcing, corrected it with full teardown and replacement of Db with mesh only, no copper clad. IOW, frustum is now all mesh except for Ds where magnetron is mounted. There was no arcing on Ds throughout any thermal testing. Plasma focused on Db, interestingly enough diagonally across from radome, not directly across axially.

Here's the video, time to do yard work, oh joy:


Looks good.

One thing that bothered me was the rapid changes in temperature measured by the IR thermometer when the magnetron was running. Could there be interference causing issues with the thermometer? As you said, "It's not an accurate way to measure the temperature."

Get a good old fashioned mechanical grill thermometer and mount it directly to the heat sink. Here's a link to one I found to show what I'm talking about.

http://www.centralrestaurant.com/Grill-Thermometer---2-in-Dial-Stainless-Steel-c177p12987.html?st-t=google_shopping&vt-k=&vt-pti=98375234695&gclid=CLfKp_Xgj8cCFUMjgQodAZoAKA

You may want to look around for what you need. That's just the first one I found doing a search.

Take a look at the dial, it's NSF certified!  :)

Offline Notsosureofit

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« Last Edit: 08/04/2015 06:04 PM by Notsosureofit »

Offline TheTraveller

Frustum design Mark 2.

Minimal operational frequency: 2.3GHz
Operational frequency: 2.45GHz
Df: 0.857
Design: Q 88k
Predicted Force generation at 100W: 50 mN (5g)
Specific Force: 0.5N/kW

Special thanks to Roger Shawyer (SPR Ltd) and to NSF Forum members for guidance and support.
« Last Edit: 08/04/2015 04:34 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 TheTraveller

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


Offline TheTraveller

I won't waste my time in calculating the exact number based on your definition of length since from your answer it is evident that you don't care, and I have better things to do.

If I didn't care I would not have taken the time to explain what length means to frustum resonance.

My resonance, at TE013, for the Mark 2 frustum design as below is 2.45GHz and not 3.9GHz.
« Last Edit: 08/04/2015 04:41 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

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