Author Topic: EM Drive Developments - related to space flight applications - Thread 3  (Read 1796168 times)

Offline DrBagelBites

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...

Is there one question in particular you would like me to ask? Not sure if I would be able to ask all of them or even more than one.

-I
As it gets closer to the date of the presentation, I will re-post all the questions in order of importance.  As there are going to be more questions posed, it is too early to rank the questions at this point in time. 

What is the deadline by which you would like to have the list of questions ranked by importance?

I live in Orlando, so you can have up until the day of the actual Q/A to have the list. As for other questions that aren't directly towards the Q/A panel and would be acceptable to ask towards the companies attending, such as rfmwguy's, really any time that you find convenient.

Offline DrBagelBites

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That is one thing I am going to definitely try and avoid: "EmDrive". It is a controversial name, and referring to it by a more generic "electromagnetic, propelantless engine" might incite more of a response. I'll let you know what each company says based off of the question!

I'll probably ask those questions during the time of visiting booths, or if I am lucky enough, to sit next to a key player during the luncheons.

I am very excited. :D
You might like to try the "Field Effect Propulsion" angle as well.  I think your assumption is correct in that "emdrive" will just result in rapidly closed doors.

Perhaps also mention the "Hypothetical concepts surrounding proposals such as present thoughts on the 4 main contenders;
Bias Drive: Works with the properties of space itself, Altering/adjusting the local properties,
Diametric Drive: Works with field sources, diametrically opposed sources reating upon the mass,
Disjunction Drive: Works with the properties of matter that create and react to a field,
Pitch Drive: Works With the field itself. a slope in scalar potential.

The common theme between them all is the asymemtric field.

While I feel those are very interesting topics, and could definitely warrant a question, I feel these are still very very close to "warp drive" and the associations that come with it. I am not saying they are the same at all, but to elicit a response that would really give some new insight as to what is happening, I feel it would be in our best interests to at least phrase it so that there isn't that connection that can completely dismantle the validity of the question.

Offline demofsky

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Only useful posts please. I notice the main detractors (four of them) who claim this thread (with 460,000 views on this one thread alone) has no place on here are always on this thread too.

Do not respond to posts that have no value. Do not quote them. Report them because they, and your response, will be removed.

And yes, to quote a removed post, I too think this is "all bollocks" but unlike those I referenced, I don't judge my own world view as the law of the land.

To build on this, if that poster were to share the results of their meep runs and show why they reached their conclusions everyone on this thread would be delighted.  To move this forward we need our bollocks quantified!
« Last Edit: 07/07/2015 12:23 AM by demofsky »

Offline arc

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While I feel those are very interesting topics, and could definitely warrant a question, I feel these are still very very close to "warp drive" and the associations that come with it. I am not saying they are the same at all, but to elicit a response that would really give some new insight as to what is happening, I feel it would be in our best interests to at least phrase it so that there isn't that connection that can completely dismantle the validity of the question.
I agree, wording and timing is crucial. 
I also admit to feeling a certain amount of both frustration and disappointment with the whole field as these things were Hot news way back in the mid 1990's.  I remember M.G.Millis, Then of NASA Lewis Research Center presented papers on these same topics... I think it was about 1996-1997 from memory?. 
Dr Whites (and others) findings would naturally follow as ongoing consequences of such things.
 
« Last Edit: 07/07/2015 12:24 AM by arc »

Offline rfmwguy

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While I feel those are very interesting topics, and could definitely warrant a question, I feel these are still very very close to "warp drive" and the associations that come with it. I am not saying they are the same at all, but to elicit a response that would really give some new insight as to what is happening, I feel it would be in our best interests to at least phrase it so that there isn't that connection that can completely dismantle the validity of the question.
I agree, wording and timing is crucial. 
I also admit to feeling a certain amount of both frustration and disappointment with the whole field as these things were Hot news way back in the mid 1990's.  I remember M.G.Millis, Then of NASA Lewis Research Center presented papers on these same topics... I think it was about 1996-1997 from memory?.
Fwiw, would not announce ur an experimenter. When I did booth duty (abt 30 years worth), off the wall claims by visitors got a chilly reception. Lots of booth critters are looking for their next sales opportunity. Best to ask a question relevant to their company and if answer not known, ask for a name and is that person available at the show. Also, have a biz card...a title of consultant was pretty commonplace. Trade shows are a blast, always had to stick close to my booth, so never roamed much...that is a privledge...

Offline DrBagelBites

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While I feel those are very interesting topics, and could definitely warrant a question, I feel these are still very very close to "warp drive" and the associations that come with it. I am not saying they are the same at all, but to elicit a response that would really give some new insight as to what is happening, I feel it would be in our best interests to at least phrase it so that there isn't that connection that can completely dismantle the validity of the question.
I agree, wording and timing is crucial. 
I also admit to feeling a certain amount of both frustration and disappointment with the whole field as these things were Hot news way back in the mid 1990's.  I remember M.G.Millis, Then of NASA Lewis Research Center presented papers on these same topics... I think it was about 1996-1997 from memory?. 
Dr Whites (and others) findings would naturally follow as ongoing consequences of such things.
Well, you had the Breakthrough Propulsion Physic Program, which is exactly what you described, ran from 1996 to 2002 and came up with the different drives that needed a breakthrough in physics before anything else, really.

However, Mills went on and made the Tau Zero Foundation, tauzero.aero, which is all about interstellar flight.

While I was not old enough to understand anything going on in mid 1990's, things are starting to pick up, I hope. However, NASA has definitely got to be careful, which they are, so as not to give people the impression they created a "warp drive".

Offline DrBagelBites

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While I feel those are very interesting topics, and could definitely warrant a question, I feel these are still very very close to "warp drive" and the associations that come with it. I am not saying they are the same at all, but to elicit a response that would really give some new insight as to what is happening, I feel it would be in our best interests to at least phrase it so that there isn't that connection that can completely dismantle the validity of the question.
I agree, wording and timing is crucial. 
I also admit to feeling a certain amount of both frustration and disappointment with the whole field as these things were Hot news way back in the mid 1990's.  I remember M.G.Millis, Then of NASA Lewis Research Center presented papers on these same topics... I think it was about 1996-1997 from memory?.
Fwiw, would not announce ur an experimenter. When I did booth duty (abt 30 years worth), off the wall claims by visitors got a chilly reception. Lots of booth critters are looking for their next sales opportunity. Best to ask a question relevant to their company and if answer not known, ask for a name and is that person available at the show. Also, have a biz card...a title of consultant was pretty commonplace. Trade shows are a blast, always had to stick close to my booth, so never roamed much...that is a privledge...

Definitely not going to say anything about experimenting. I am simply someone who has been following what has been going on and am curious on the company's development in that field.

Business cards are being created as we speak. :)

Offline Slyver

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...
Also, did Dr. Tajmar treat his EM Drive as a thruster or a ratchet? According to SPR and TheTraveler, if he was expecting it to thrust, he probably got Null results as is to be expected, since it is not intended to thrust without some outside influence to make it ratchet.
Todd

Well, I understand that Tajmar will not present his results under vacuum as "null results" but as valid results.
As to the outside influence to motivate the EM Drive, how did Yang motivate her EM Drive to thrust?
and more generally, can you think of a question we could ask Tajmar along these lines?  (I have tried to construct such a question and it is difficult to do in a few words, without appearing unintelligible, as first one has to describe what one means by "as a ratchet under outside influence".  I have enough trouble understanding what Shawyer may mean by that, much less how to construct such a question in an intelligible manner)

It would be great if you and others could think of how to ask such a question to Tajmar, with a minimum of words and in a way that he understands what the question is about.

Perhaps the "Ratchet Question" could best be phrased as to whether Prof. Tajmar saw the "EM drive" as a purely closed system or an open one that interacted with its environment.  If Tajmar saw "EM drives" as closed, then did they have their own inertial frame of reference.

Does this work?

I think that may not be specific enough. I think this is an axiom worthy of experimentation.  In an attempt to query more particularly, maybe something like:

----
One experimenter of a similar device has suggested that it works as an “inertial ratchet” whereby when it is turned on, the inertia in one direction along the longitudinal axis is less than the inertia in the opposite direction. This suggests that an induced mechanical vibration of the system might increase the measured force. Alternatively, it suggests that the better the experiment is at decreasing vibrations in the system in an attempt to reduce the noise, the lower the force that will be measured. Has this idea been tested?
----

I’m not in love with the way I have phrased it.  If I hadn’t been reading these threads for almost a year I would have difficulty entertaining the idea as anything remotely possible, however; as Tajmar is giving a talk about an “impossible” device, he may be open to it.

If he has tested it and found it to not have been true, great. If he has found it to be true, he will almost certainly mention it in the talk and the question is irrelevant. If he has not been introduced to the idea, planting the thought into someone such as him might be fantastic for verifying/falsifying the axiom.

It is also possible that the question may have at least tentative answers before the conference from some of the experimenters here, and/or the ideas behind the question could change substantially.

Offline Rodal

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Background: previous post with Poynting Vector Field plots for time steps 03 through 13:  http://forum.nasaspaceflight.com/index.php?topic=37642.msg1399795#msg1399795

I have, from aero's csv files,

1) Calculated the Poynting vector component in the longitudinal direction (the components in the transverse direction are self-cancelling, since they point in opposite directions away from the axis)

2) Determined the location of the local maximum on the wave-pattern immediately downstream (towards the big base) from the antenna location: it is column (x location) 149.  Transverse location (either y or z): 132.5

3) calculated the time fluctuation of the Poynting vector component in the longitudinal direction at that local maximum location.  It is attached below.

We see that:

1) The average over an integer number of periods is not zero.  It is negative, meaning that it points from the small base towards the big base.  (We had previously shown this with 3D and also with vector field plots)

2) The magnitude of the Poynting vector (averaged over integer time periods) grows with time

This is all fully consistent with a force acting (to balance momentum) pointing towards the small base.  Although consistent, not yet a proof, since:

1) We only have available data for the last 13 steps out of ~325 time steps.   We don't know whether this is a transient or how representative it is from the long-term response.

2) This flux (power/area) may get dissipated into heat. 

It has to be shown why is the Poynting vector growing with time, how long does this go on for, and whether this all goes into losses at the walls or whether (and if so how) this Poynting vector gets converted into a force.

Units are in Meep units. [Have to take into account also aero's scale factor to figure out SI units]

The dots represent the data points.  The smooth curves between the points are interpolated.

We should also be able from these data to calculate the frequency if we knew the time step (the frequency of the Poynting vector should be twice the frequency of the microwave field) and we should also be able to calculate the rate of growth per unit time.
« Last Edit: 07/07/2015 01:58 AM by Rodal »

Offline zaphod_vi

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I don't know whether this is stating the obvious, but one of the TheTraveller's recent posts made me go ahh. With Shawyer's experiments, if the drive is stationary in a low noise environment and switched on, it does not move. Well, it may generate some thrust, but not enough to overcome any friction in the test equipment. It needs an external stimulus or acceleration to get moving. Once moving, and free to accelerate, the drive will generate thrust and continue to accelerate. A sort of feed back loop as it were. Which explains Shawyer's rotating test rig. With a balance scale, when the drive's velocity falls to zero when it is at the top/bottom, the thrust should drop off. However, having a balance scale with a way to inject a known initial acceleration to the drive might be a good way to test.

To my somewhat limited understanding, this looks like some kind of relativity problem. When stationary, or at constant velocity, photons are hitting the walls in the same reference frame. However, with the drive under acceleration, photons will be hitting the walls in different frames, and in some fashion generating thrust.

For the EM drive theories currently being discussed, do they require an initial impetus or acceleration to get the drives to move or not. If not, then this goes against what Shawyer is saying.

Similarly, for analysis being done. Is this assuming a drive at zero or constant velocity, or a drive under acceleration.

It may also be that the earth's rotation is going to have an effect upon the EM drive as the photons bounce around inside.

And if EM drives do work, perhaps they'll have an analogue to the car choke, which gives them a shake to get them started.

Offline SeeShells

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I thought I would chime in with questions for the AIAA conference. I am going to be attending the event, so I will be able to report back to you guys about what happens, other questions that were asked, etc.

Let me know of a couple of definite questions that anyone would want me to ask during the Q and A, and I'll be sure to ask them and report back the answers. :)

-I
Maybe if you could video what you might find important and post the video or even pictures. Only if you are allowed to.

Shell

Offline aero

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I have, from aero's csv files,

1) Calculated the Poynting vector component in the longitudinal direction (the components in the transverse direction are self-cancelling, since they point in opposite directions away from the axis)

2) Determined the location of the local maximum on the wave-pattern immediately downstream (towards the big base) from the antenna location: it is column (x location) 149

3) calculated the time fluctuation of the Poynting vector component in the longitudinal direction at that local maximum location.  It is attached below.

We see that:

1) The average over an integer number of periods is not zero.  It is negative, meaning that it points from the small base towards the big base.  (We had previously shown this with 3D and also with vector field plots)

2) The magnitude of the Poynting vector (averaged over integer time periods) grows with time

This is all fully consistent with a force acting (to balance momentum) pointing towards the small base.  Although consistent, not yet a proof, since:

1) We only have available data for the last 13 steps out of ~325 time steps.   We don't know whether this is a transient or how representative it is from the long-term response.

2) This flux (power/area) may get dissipated into heat. 

It has to be shown why is the Poynting vector growing with time, how long does this go on for, and whether this all goes into losses at the walls or whether (and if so how) this Poynting vector gets converted into a force.

Units are in Meep units. [Have to take into account also aero's scale factor to figure out SI units]

The dots represent the data point.  The smooth curves between the points are interpolated.

We should also be able from these data to calculate the frequency if we knew the time step (the frequency of the Poynting vector should be twice the frequency of the microwave field) and we should also be able to calculate the rate of growth per unit time.

My latest run has completed. This is the output at the final step.

; run time set to 13.052188647619047 meep time                               This is printed output from control file set.
;Meep progress: 13.054/13.052188647619047 = 100.0% done in 6479.3s, -0.9s to go
;run 0 finished at t = 13.054 (6527 timesteps)

It looks to me like the number you want is dt = 13.054/6527 which equals  0.002, a nice number. Or maybe you want to use the 100% done numbers.

Anyway, you should be able to use this dt for any of the csv files from the h5 files with dimensions 247x264x264 or any run of 32 cycles with resolution =250 and frequency = 2.45 GHz. That is, they should have those dimensions.
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Offline SeeShells

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Background: previous post with Poynting Vector Field plots for time steps 03 through 13:  http://forum.nasaspaceflight.com/index.php?topic=37642.msg1399795#msg1399795

2) The magnitude of the Poynting vector (averaged over integer time periods) grows with time

This is all fully consistent with a force acting (to balance momentum) pointing towards the small base.  Although consistent, not yet a proof, since:

It has to be shown why is the Poynting vector growing with time, how long does this go on for, and whether this all goes into losses at the walls or whether (and if so how) this Poynting vector gets converted into a force.


At what rate do you see the poynting vector grow?

Shell

Offline Rodal

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Background: previous post with Poynting Vector Field plots for time steps 03 through 13:  http://forum.nasaspaceflight.com/index.php?topic=37642.msg1399795#msg1399795

2) The magnitude of the Poynting vector (averaged over integer time periods) grows with time

This is all fully consistent with a force acting (to balance momentum) pointing towards the small base.  Although consistent, not yet a proof, since:

It has to be shown why is the Poynting vector growing with time, how long does this go on for, and whether this all goes into losses at the walls or whether (and if so how) this Poynting vector gets converted into a force.


At what rate do you see the poynting vector grow?

Shell
Did not get the Finite Difference data to calculate that until a few minutes ago (message from aero just above yours :) ) .  Will need to convert units and calculate.  Got some $$$ paying work to do now, maybe I'll calculate it tomorrow :)
Also have to find previous posts from aero with link to Meep units conversion.

QUESTION TO AERO: is the scale factor the same in all the runs ?
« Last Edit: 07/07/2015 02:14 AM by Rodal »

Offline SeeShells

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Background: previous post with Poynting Vector Field plots for time steps 03 through 13:  http://forum.nasaspaceflight.com/index.php?topic=37642.msg1399795#msg1399795

2) The magnitude of the Poynting vector (averaged over integer time periods) grows with time

This is all fully consistent with a force acting (to balance momentum) pointing towards the small base.  Although consistent, not yet a proof, since:

It has to be shown why is the Poynting vector growing with time, how long does this go on for, and whether this all goes into losses at the walls or whether (and if so how) this Poynting vector gets converted into a force.


At what rate do you see the poynting vector grow?

Shell
Did not get the Finite Difference data to calculate that until a few minutes ago (message from aero just above yours :) ) .  Will need to convert units and calculate.  Got some $$$ paying work to do now, maybe I'll calculate it tomorrow :)
Understand. No problem.

Offline rfmwguy

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I don't know whether this is stating the obvious, but one of the TheTraveller's recent posts made me go ahh. With Shawyer's experiments, if the drive is stationary in a low noise environment and switched on, it does not move. Well, it may generate some thrust, but not enough to overcome any friction in the test equipment. It needs an external stimulus or acceleration to get moving. Once moving, and free to accelerate, the drive will generate thrust and continue to accelerate. A sort of feed back loop as it were. Which explains Shawyer's rotating test rig. With a balance scale, when the drive's velocity falls to zero when it is at the top/bottom, the thrust should drop off. However, having a balance scale with a way to inject a known initial acceleration to the drive might be a good way to test.

To my somewhat limited understanding, this looks like some kind of relativity problem. When stationary, or at constant velocity, photons are hitting the walls in the same reference frame. However, with the drive under acceleration, photons will be hitting the walls in different frames, and in some fashion generating thrust.

For the EM drive theories currently being discussed, do they require an initial impetus or acceleration to get the drives to move or not. If not, then this goes against what Shawyer is saying.

Similarly, for analysis being done. Is this assuming a drive at zero or constant velocity, or a drive under acceleration.

It may also be that the earth's rotation is going to have an effect upon the EM drive as the photons bounce around inside.

And if EM drives do work, perhaps they'll have an analogue to the car choke, which gives them a shake to get them started.
A photon has zero rest mass...to me, its a vibration; a wave/particle in a medium...what we call space. Logic would state that this medium is not empty. What it contains is not fully understood, imho. If this effect is real, the direction and reflection of energy in a frustum is interacting upon it...assymetrically, meaning a physical dimension is tunneling/focusing photons. What I cannot fathom yet is what makes this closed system open...more open on one end than the other. Is the effect a push or pull? Attraction or repulsion? Or perhaps some hybrid of both. In another sense, we swim in a soup of em...em existing only because of a medium we fail to understand. We could not use a paddle if we didn't understand the water...perhaps its the water we have questions about.

Online Chris Bergin

So I've just had the cops at the door saying the neighbors are complaining about the noise coming from this thread ;) I see mod notes all over the place, so here's the deal.

1) Always, always, always remember this thread has to be about space flight applications. That's because we're a space flight site. You'd get away with talking about how this is the key to your plans to create an anti-gravity device that you're going to sell on Ebay over at the www.superwackyphysics.net forum, but not here.

2) Lots and lots of people read the threads here (all threads - this isn't some special "everyone's reading it, you should change the name of the site" thread. This is a pretty busy site. Heck if you sneeze SpaceX, hoards of people start mashing their F5 keys like a global event is about to occur). As such, your posts need to be worthwhile, otherwise all those people *reading the thread* sigh with disappointment...and some write me a 20 page e-mail about how I should read every post and personally edit them to fit the site's "tone" (that has happened a few times! ;D ) I don't get paid enough for that (I don't get paid).

Remember, this isn't some chat where only the people posting are reading. You can see from the view count those posting are less than 0.1 percent of those reading this thread. You wouldn't stand in the middle of a busy street and say something silly....same deal in a thread like this.

3) Loooooooooooong threads wander. It's natural. So I think we'll look to start a Thread 4 for this subject this week.

So let's all focus, be civil, be productive and we can all get on with our business ;)

Offline aero

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Background: previous post with Poynting Vector Field plots for time steps 03 through 13:  http://forum.nasaspaceflight.com/index.php?topic=37642.msg1399795#msg1399795

2) The magnitude of the Poynting vector (averaged over integer time periods) grows with time

This is all fully consistent with a force acting (to balance momentum) pointing towards the small base.  Although consistent, not yet a proof, since:

It has to be shown why is the Poynting vector growing with time, how long does this go on for, and whether this all goes into losses at the walls or whether (and if so how) this Poynting vector gets converted into a force.


At what rate do you see the poynting vector grow?

Shell
Did not get the Finite Difference data to calculate that until a few minutes ago (message from aero just above yours :) ) .  Will need to convert units and calculate.  Got some $$$ paying work to do now, maybe I'll calculate it tomorrow :)
Also have to find previous posts from aero with link to Meep units conversion.

QUESTION TO AERO: is the scale factor the same in all the runs ?

Well, lately it has been 0.3. I think you're safe using 0.3 with any data I've put on Google drive. (I'm sure of it.)
and here: http://meepunits.wikia.com/wiki/Meep_unit_transformation_Wiki
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Offline Rodal

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...
;Meep progress: 13.054/13.052188647619047 = 100.0% done in 6479.3s, -0.9s to go
;run 0 finished at t = 13.054 (6527 timesteps)

It looks to me like the number you want is dt = 13.054/6527 which equals  0.002, a nice number. Or maybe you want to use the 100% done numbers.

Anyway, you should be able to use this dt for any of the csv files from the h5 files with dimensions 247x264x264 or any run of 32 cycles with resolution =250 and frequency = 2.45 GHz. That is, they should have those dimensions.
6527 timesteps ?  I thought that there were only ~325 time steps or so

Offline Prunesquallor

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So I've just had the cops at the door saying the neighbors are complaining about the noise coming from this thread ;) I see mod notes all over the place, so here's the deal.

1) Always, always, always remember this thread has to be about space flight applications. That's because we're a space flight site. You'd get away with talking about how this is the key to your plans to create an anti-gravity device that you're going to sell on Ebay over at the www.superwackyphysics.net forum, but not here.

2) Lots and lots of people read the threads here (all threads - this isn't some special "everyone's reading it, you should change the name of the site" thread. This is a pretty busy site. Heck if you sneeze SpaceX, hoards of people start mashing their F5 keys like a global event is about to occur). As such, your posts need to be worthwhile, otherwise all those people *reading the thread* sigh with disappointment...and some write me a 20 page e-mail about how I should read every post and personally edit them to fit the site's "tone" (that has happened a few times! ;D ) I don't get paid enough for that (I don't get paid).

Remember, this isn't some chat where only the people posting are reading. You can see from the view count those posting are less than 0.1 percent of those reading this thread. You wouldn't stand in the middle of a busy street and say something silly....same deal in a thread like this.

3) Loooooooooooong threads wander. It's natural. So I think we'll look to start a Thread 4 for this subject this week.

So let's all focus, be civil, be productive and we can all get on with our business ;)

The dilemma I see is that to intelligently discuss emdrive applicability to spaceflight, its operating characteristics need to be debated (assuming it operates at all). Right now, there are several mutually exclusive theories on what those characteristics might be (constant thrust/power, velocity limiting, inertial ratchet, etc.).   In my view the theoretical and experimental discussions are vital.
Retired, yet... not

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