Author Topic: EM Drive Developments - related to space flight applications - Thread 3  (Read 1804976 times)

Offline rfmwguy

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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
Its a small step forward, at least a challenge to the status quo to defend their belief systems. It certainly can bring out the best and worst in people...interesting, fersure.

Offline ventsyv

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Hello. I've been following the EM drive developments in the last few months and I tried reading through the hundreds of posts on this forum, but found them confusing due to the multiple long running conversations and high SNR.
Can someone summarize the current state of affairs (including the physics)?

As far as I understand it, there have been 3 independent studies that have measured small amounts of thrust. Some of the tests were in atmosphere, some were in hard vacuum and all measured thrust above the error threshold of the instruments.
The latest test also added insulation to try to eliminate thermal and electromagnetic(?) interference.
The theory that seem go get the most traction is that the drive pushes against the quantum vacuum even though the mainstream theory says you should not be able to push against it.

I'm a bit confused about the direction of the thrust that was measured. My understanding is that thrust was measure in the opposite  direction of where it was expected and the latest test measured thrust in the orthogonal direction after the power was switched off? Can someone elaborate on this?

Also, what power ranges have been tested and is there a model that can predict the thrust output?
Greatly appreciated.

Offline Josave

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Hello,

This is an updated place for the information flowing in this forum:

http://emdrive.wiki/Main_Page




Offline ventsyv

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Great! Thanks!

Offline OttO

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I stumbled on this:

Detection of the extraordinary transverse pressure in optical fields

http://metaconferences.org/ocs/public/conferences/9/pdf/3204.pdf

"We predict theoretically and measure experimentally extraordinary transverse force, which appears in inhomogeneous optical fields. In contrast to the known radiation-pressure and gradient optical forces, this weak force is orthogonal to both the momentum (wave vector) and intensity gradient in the field. Moreover, this transverse force crucially depends on the spin (circular polarization) of light"

Offline meberbs

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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

Note that most of the post was referring to an open system where only one mirror is attached to the vehicle. If this explains EM drive thrust, the Q factor that matters would be between the device and the chamber walls. Still, assuming there is some new physics behind the EM drive, similar calculations would probably apply.

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.

I think you are filling in some numbers wrong. v2/v1 = 0 when a=0 means that the photon is absorbed, transferring all of its energy to the mirror. This limit comes from either the m-> 0, for a massless mirror, or v1-> inf for a photon with infinite frequency.

The example I used before had a as about 450,000 and gave 0.999997 as a result: http://www.wolframalpha.com/input/?i=sqrt%28+a^2+%2B+4*a+%2B+1%29+-a-1%2C+a+%3D+1e-35*9e16%2F+%286.626e-34*3e9+%29

My ability to take limits correctly seems non-existent this morning, but the limit as a-> inf should be 1, and the function is monotonic for a >0, meaning that for a> 0 it will always be between 0 and 1. This can be seen on the graph here: http://www.wolframalpha.com/input/?i=sqrt%28+a^2+%2B+4*a+%2B+1%29+-a-1

*If the links don't work right for you, try pasting them directly or seeing if you got a message about cross site scripting. When I click on the links, firefox deletes all of the + and - and () from the equation.

Offline Fugudaddy

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Old sailors trick.
Use 0.25m long pieces of old cassette tape. Very low mass but high surface area.
What I expect to see is air being thrown outward from the rotating table and being drawn up from the floor and down from the roof to make up for the air being thrown outward.

Wouldn't those potentially respond magnetically as well as via air currents? Of course, any plastic type material like that will respond to electrical/static buildup (think old-fashioned christmas-tree icicles) so may not be giving the sort of result you want if you're looking for just air currents.

Online Rodal

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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

Note that most of the post was referring to an open system where only one mirror is attached to the vehicle. If this explains EM drive thrust, the Q factor that matters would be between the device and the chamber walls. Still, assuming there is some new physics behind the EM drive, similar calculations would probably apply.

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.

I think you are filling in some numbers wrong. v2/v1 = 0 when a=0 means that the photon is absorbed, transferring all of its energy to the mirror. This limit comes from either the m-> 0, for a massless mirror, or v1-> inf for a photon with infinite frequency.

The example I used before had a as about 450,000 and gave 0.999997 as a result: http://www.wolframalpha.com/input/?i=sqrt%28+a^2+%2B+4*a+%2B+1%29+-a-1%2C+a+%3D+1e-35*9e16%2F+%286.626e-34*3e9+%29

My ability to take limits correctly seems non-existent this morning, but the limit as a-> inf should be 1, and the function is monotonic for a >0, meaning that for a> 0 it will always be between 0 and 1. This can be seen on the graph here: http://www.wolframalpha.com/input/?i=sqrt%28+a^2+%2B+4*a+%2B+1%29+-a-1

*If the links don't work right for you, try pasting them directly or seeing if you got a message about cross site scripting. When I click on the links, firefox deletes all of the + and - and () from the equation.

Meberbs is correct, v2 approaches v1 as a goes to Infinity. 

v2 never reaches v1 for finite values of a:

Limit[Sqrt[a^2 + 4*a + 1] - a - 1, a -> Infinity] = 1


N[Limit[Sqrt[a^2 + 4*a + 1] - a - 1, a -> 1000]] = 0.998503

N[Limit[Sqrt[a^2 + 4*a + 1] - a - 1, a -> 100]] = 0.985293

N[Limit[Sqrt[a^2 + 4*a + 1] - a - 1, a -> 10]] = 0.874342

N[Limit[Sqrt[a^2 + 4*a + 1] - a - 1, a -> 2]] = 0.605551

N[Limit[Sqrt[a^2 + 4*a + 1] - a - 1, a -> 1]] = 0.44949

Limit[Sqrt[a^2 + 4*a + 1] - a - 1, a -> 0] = 0
« Last Edit: 08/06/2015 03:08 PM by Rodal »

Offline OttO

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Detection of the extraordinary transverse pressure in optical fields

http://metaconferences.org/ocs/public/conferences/9/pdf/3204.pdf

Could this be in action in our case?
If the waves are polarized in the cavity this pressure should induce a force toward the small base, no?
Transient yes but it could be a factor while we inflate the pressure tank  (I like this image :) )
« Last Edit: 08/06/2015 03:14 PM by OttO »

Offline TheTraveller

Note that most of the post was referring to an open system where only one mirror is attached to the vehicle. If this explains EM drive thrust, the Q factor that matters would be between the device and the chamber walls. Still, assuming there is some new physics behind the EM drive, similar calculations would probably apply.

Open, closed doesn't really matter.

What you showed, on a per bounce example, is the energy lost to a bounced EMwave, the degraded photon with a very slight red shift, is VERY small and that doing multiple bounces increases the Force as there is more than ample energy available in the bounced EM wave to support MANY bounces.

Which is what both Shawyer and Prof Yang have been saying for years.

EMDrive generated Specific Force scales with Q as attached.
"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

Old sailors trick.
Use 0.25m long pieces of old cassette tape. Very low mass but high surface area.
What I expect to see is air being thrown outward from the rotating table and being drawn up from the floor and down from the roof to make up for the air being thrown outward.

Wouldn't those potentially respond magnetically as well as via air currents? Of course, any plastic type material like that will respond to electrical/static buildup (think old-fashioned christmas-tree icicles) so may not be giving the sort of result you want if you're looking for just air currents.

Will have Smoke Sticks to allow air flow to be seen.
"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

Has anyone heard of the experiments performed by David Pares?
http://www.paresspacewarpresearch.org/index.htm

Looks like he is measuring forces from a fractal tripole array. I haven't scrutinized his pages very thoroughly yet, but at first glance his numbers seem 'too good to be true'.   

But maybe an asymmetric warp bubble could be responsible for all EM Drive forces observed?
https://forum.nasaspaceflight.com/index.php?topic=36313.msg1362403#msg1362403

Since when did Eagleworks have 100W of Rf to fill a frustum with?
"As for me, I am tormented with an everlasting itch for things remote. I love to sail forbidden seas.
Herman Melville, Moby Dick

Offline zellerium

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Since when did Eagleworks have 100W of Rf to fill a frustum with?

 I found this picture on a google image search. Didn't notice the power level. Perhaps it is just a simulation?
I was simply relating the two field geometries, wondering if there is anything to Pares' experiments.
« Last Edit: 08/06/2015 04:12 PM by zellerium »

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.

I think you are filling in some numbers wrong. v2/v1 = 0 when a=0 means that the photon is absorbed, transferring all of its energy to the mirror. This limit comes from either the m-> 0, for a massless mirror, or v1-> inf for a photon with infinite frequency.

The example I used before had a as about 450,000 and gave 0.999997 as a result: http://www.wolframalpha.com/input/?i=sqrt%28+a^2+%2B+4*a+%2B+1%29+-a-1%2C+a+%3D+1e-35*9e16%2F+%286.626e-34*3e9+%29

My ability to take limits correctly seems non-existent this morning, but the limit as a-> inf should be 1, and the function is monotonic for a >0, meaning that for a> 0 it will always be between 0 and 1. This can be seen on the graph here: http://www.wolframalpha.com/input/?i=sqrt%28+a^2+%2B+4*a+%2B+1%29+-a-1

*If the links don't work right for you, try pasting them directly or seeing if you got a message about cross site scripting. When I click on the links, firefox deletes all of the + and - and () from the equation.
Oops. I'd convinced myself yesterday that v2/v1 could exceed 1 by an inspection argument, but I'm going to have to fire the inspector. I now agree it cannot exceed 1. wolframalpha worked fine.

Offline SteveD

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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

Well it looks like venture capital funds got involved with SPR and Cannae before the publication of the first peer reviewed paper.  At this rate somebody will be powering a homebuilt aircraft with an EMdrive while the academic community is still debating if the results are worthy of publication.  That said, would like to see clear thrust before concluding that something is actually happening.

Offline rfmwguy

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Since when did Eagleworks have 100W of Rf to fill a frustum with?

 I found this picture on a google image search. Didn't notice the power level. Perhaps it is just a simulation?
I was simply relating the two field geometries, wondering if there is anything to Pares' experiments.
I've read local newspaper and saw local TV reports...blue sky promotional material, no peer papers, not connected with any EM drive people that I know of.

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
Oh please.

To 16 significant digits.
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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.

To 16 significant digits.
Which in this context means down to roughly one millionth the diameter of an atom. So again - perleez!

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
Oh please.

To 16 significant digits.
Which in this context means down to roughly one millionth the diameter of an atom. So again - perleez!

Don't know what your problem is - that number is internally calculated based on input to the model. It was in response to a question about the internal dimensions of the numerical lattice, not the physical model. The model is input significant to 2 decimal places in length, but the lattice dimensions are calculated internally and are significant to the resolution of the machine. 

Do you really want to debate this point?
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Offline deltaMass

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I understand. I am pointing out that the number you're quoting has dubious physical significance. The last 6 digits - at least - have no effect on anything real. . That's beyond debate, so I have no problem stating these facts.

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