Author Topic: EM Drive Developments - related to space flight applications - Thread 3  (Read 1799418 times)

Online Rodal

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@Rodal

Let me know if your mind has changed on which question should be asked. I'll be checking in on the NSF throughout the day up to the talk.

-I


1) BIG QUESTION: consider the possibility that the EM Drive is not an experimental artifact.  Of all the theories to explain it as space propulsion (Shawyer, McCulloch, Quantum Vacuum, General Relavity, etc.), which one would you favor and why?

2) TECHNICAL QUESTION: the worrisome side force in the torsional balance experiments, could it be due to the bloody great hole on the side of the frustum, asymmetrically placed (according to the COMSOL figure) producing a side force due to the bloody great waveguide ?

__________

Dr. Bagelbytes, I would not waste a question asking whether he will continue his research,  he finishes the report by stating what the next steps in this research are going to be.  Whether he continues this research or not is a function of whether he continues being funded for the research, pure and simple.  I bet you that he will conduct research on everything he can be funded for, as long as he can be funded for it.  It is just a question of supervising students.  The more funding he gets, the more projects he has, the better for his rise at the University.
« Last Edit: 07/28/2015 04:09 PM by Rodal »

Offline Prunesquallor

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The idea is to not fire a beam through atmosphere, since this is a space-based technology. See also DE-STARS

BL asked for an example.  I don't know of a space-based example, but they probably exist.
Retired, yet... not

Offline DrBagelBites

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@Rodal

Let me know if your mind has changed on which question should be asked. I'll be checking in on the NSF throughout the day up to the talk.

-I


1) BIG QUESTION: consider the possibility that the EM Drive is not an experimental artifact.  Of all the theories to explain it as space propulsion (Shawyer, McCulloch, Quantum Vacuum, General Relavity, etc.), which one would you favor and why?

2) TECHNICAL QUESTION: the worrisome side force in the torsional balance experiments, could it be due to the bloody great hole on the side of the frustum, asymmetrically placed (according to the COMSOL figure) producing a side force due to the bloody great waveguide ?

__________

Dr. Bagelbytes, I would not waste a question asking whether he will continue his research,  he finishes the report by stating what the next steps in this research are going to be.  Whether he continues this research or not is a function of whether he continues being funded for the research, pure and simple.  I bet you that he will conduct research on everything he can be funded for, as long as he can be funded for it.  It is just a question of supervising students.  The more funding he gets, the more projects he has, the better for his rise at the University.

Fair enough.  I'll start with the non-technical question, if time allows, the technical question will be asked, with omission of "bloody". ;)

-I

Offline SeeShells

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ATTN: Calling all Meeps.

Digging through ways to model a loop antenna I came across this simpler way to model one. Not sure if you can do it but I'd thought I'd throw it out here and let you comment on it.

http://www.silabs.com/Support%20Documents/TechnicalDocs/AN639.pdf

Shell

ADDED: The reason is it can excite a TE wave down the frustum when it's parallel to the plates.
« Last Edit: 07/28/2015 04:49 PM by SeeShells »

Offline Star One

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I wonder if there's any chance of an article being produced that reports this paper/talk properly.

Offline SH

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I think Tajmar's latest validation of the EM Drive is actually the subtle unraveling of it.

From Fig 5a, it is demonstrated that adding controls for thermal convection gets rid of most of the anomalous force, which naturally begs the question whether the slight force remaining after "controlling" for thermal effects is in fact just the remaining thermal effects not controlled for.

Tajmar argues that the positive force readings in a vacuum prove there is some other non-thermal effect.  I disagree.

One can see from the pictures that the torsion balance which the EmDrive is mounted on is made out of aluminum, which has high thermal conductivity.  Thus even if there are no gaseous thermal convection, there can still be thermal effects against the housing.

The fact that force remains after the device is turned off, which is proportional to the temperature of the device (see Fig 8a), seems pretty damning evidence of this explanation.

Offline D_Dom

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I wonder if there's any chance of an article being produced that reports this paper/talk properly.
Considering Dr BB will be live blogging it on reddit can/should he use that as source material for an article here?
Space is not merely a matter of life or death, it is considerably more important than that!

Offline Chrochne

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I think Tajmar's latest validation of the EM Drive is actually the subtle unraveling of it.

From Fig 5a, it is demonstrated that adding controls for thermal convection gets rid of most of the anomalous force, which naturally begs the question whether the slight force remaining after "controlling" for thermal effects is in fact just the remaining thermal effects not controlled for.

Tajmar argues that the positive force readings in a vacuum prove there is some other non-thermal effect.  I disagree.

One can see from the pictures that the torsion balance which the EmDrive is mounted on is made out of aluminum, which has high thermal conductivity.  Thus even if there are no gaseous thermal convection, there can still be thermal effects against the housing.

The fact that force remains after the device is turned off, which is proportional to the temperature of the device (see Fig 8a), seems pretty damning evidence of this explanation.

Your logic is very good and argumentation as well Mr. SH, but you are going againts a person that is well known for avoiding experimental error. I believe that only experiments now, not only simply "disagree" will help now, if you are looking to close the chapter of the EmDrive for good.

Offline Star One

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I wonder if there's any chance of an article being produced that reports this paper/talk properly.
Considering Dr BB will be live blogging it on reddit can/should he use that as source material for an article here?

Yes that's a good idea.

I'm afraid this thread is probably going to get full of trolls as it did last time so I fear it may need locking & a new one starting later.

Offline wallofwolfstreet

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I think Tajmar's latest validation of the EM Drive is actually the subtle unraveling of it.

...

I have to agree.  Whether Tajmar really is as great at eliminating experimental error as others have said, just by examining the paper it clear that things have not been fully accounted for.  The force is still changing with orientation, and there is unexplainable force when there really shouldn't be.

Why do people keep saying that Tajmar is so great at eliminating experimental errors (genuine question)?  Is there any source that specifically indicates this, or is it just generally accepted knowledge?  His wikipedia page doesn't offer any insights other than he has previously been involved in testing other fringe stuff.  I knew of him before the emdrive, and it was only for his involvement in fringe propulsion concepts, like Podkletnov's gravity modification. 

Offline WarpTech

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@Rodal

Let me know if your mind has changed on which question should be asked. I'll be checking in on the NSF throughout the day up to the talk.

-I


1) BIG QUESTION: consider the possibility that the EM Drive is not an experimental artifact.  Of all the theories to explain it as space propulsion (Shawyer, McCulloch, Quantum Vacuum, General Relavity, etc.), which one would you favor and why?

2) TECHNICAL QUESTION: the worrisome side force in the torsional balance experiments, could it be due to the bloody great hole on the side of the frustum, asymmetrically placed (according to the COMSOL figure) producing a side force due to the bloody great waveguide ?

__________

Dr. Bagelbytes, I would not waste a question asking whether he will continue his research,  he finishes the report by stating what the next steps in this research are going to be.  Whether he continues this research or not is a function of whether he continues being funded for the research, pure and simple.  I bet you that he will conduct research on everything he can be funded for, as long as he can be funded for it.  It is just a question of supervising students.  The more funding he gets, the more projects he has, the better for his rise at the University.

Looking at the COMSOL figure, it seems to me that the waveguide is centered, but the image is showing a cut-away cross section. So it appears that the waveguide is cut in half, down the middle. We're only seeing one half of it, so it appears to be off-center.
Todd


Offline DrBagelBites

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I wonder if there's any chance of an article being produced that reports this paper/talk properly.
Considering Dr BB will be live blogging it on reddit can/should he use that as source material for an article here?

You mean for me to write an article? Or am I misunderstanding?

Offline deltaMass

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The idea is to not fire a beam through atmosphere, since this is a space-based technology. See also DE-STARS

BL asked for an example.  I don't know of a space-based example, but they probably exist.
Sadly it is still early days.  The up front cash barrier is a deterrent to an early start. Ditto the lack of vision. Seems to me that bopping around the solar system while using next to no fuel would be A Good Thing. It's the closest thing to propellantless that we know for sure will work. It is also a worthy interstellar precursor technology (probably the only viable one right now). When you're leveraging off 3*1026 Watts, there is a lot that can be done.
« Last Edit: 07/28/2015 05:27 PM by deltaMass »

Offline DrBagelBites

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Looking at the COMSOL figure, it seems to me that the waveguide is centered, but the image is showing a cut-away cross section. So it appears that the waveguide is cut in half, down the middle. We're only seeing one half of it, so it appears to be off-center.
Todd

I think it would be good to have this solved before the talk so as no to ask a question based on an incorrect premise.

Online Rodal

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@Rodal

Let me know if your mind has changed on which question should be asked. I'll be checking in on the NSF throughout the day up to the talk.

-I


1) BIG QUESTION: consider the possibility that the EM Drive is not an experimental artifact.  Of all the theories to explain it as space propulsion (Shawyer, McCulloch, Quantum Vacuum, General Relavity, etc.), which one would you favor and why?

2) TECHNICAL QUESTION: the worrisome side force in the torsional balance experiments, could it be due to the bloody great hole on the side of the frustum, asymmetrically placed (according to the COMSOL figure) producing a side force due to the bloody great waveguide ?

__________

Dr. Bagelbytes, I would not waste a question asking whether he will continue his research,  he finishes the report by stating what the next steps in this research are going to be.  Whether he continues this research or not is a function of whether he continues being funded for the research, pure and simple.  I bet you that he will conduct research on everything he can be funded for, as long as he can be funded for it.  It is just a question of supervising students.  The more funding he gets, the more projects he has, the better for his rise at the University.

Looking at the COMSOL figure, it seems to me that the waveguide is centered, but the image is showing a cut-away cross section. So it appears that the waveguide is cut in half, down the middle. We're only seeing one half of it, so it appears to be off-center.
Todd
I thought of that, but for that perspective to be consistent, the big base and the small base should also be cut.  But the big base and the small base are not cut: the full perimeter circular contours (which shows as an ellipse due to the view) of the bases are fully shown.  If the waveguide would be symmetric, the full contour of the waveguide  would also be shown.   Anyway, whether the waveguide is asymmetric or whether it is symmetric and the COMSOL drawing was not consistently shown in 3D is something that perhaps Tajmar could answer after the session is over, together with confirming whether the dimensions are off by a factor of 2.


________________________

I enclose strictly for discussion, research and illustration purposes Fig. 2 a of Tajmar et.al. COMSOL FEA analysis for comparison purposes to address the above question


 “…for purposes such as criticism, comment, news reporting, scholarship, or research…” under US Fair Use

http://fairuse.stanford.edu/overview/fair-use/what-is-fair-use/

This is the  American Institute of Aeronautics and Astronautics link to Martin Tajmar's et.al. paper, that should be obtained from the American Institute of Aeronautics and Astronautics:

Direct Thrust Measurements of an EM Drive and Evaluation of Possible Side-Effects  M. Tajmar and G. Fiedler
51st AIAA/SAE/ASEE Joint Propulsion Conference

http://arc.aiaa.org/doi/pdf/10.2514/6.2015-4083
« Last Edit: 07/28/2015 05:41 PM by Rodal »

Online Rodal

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Looking at the COMSOL figure, it seems to me that the waveguide is centered, but the image is showing a cut-away cross section. So it appears that the waveguide is cut in half, down the middle. We're only seeing one half of it, so it appears to be off-center.
Todd

I think it would be good to have this solved before the talk so as no to ask a question based on an incorrect premise.

Concerning asking the question, all you have to do is to phrase it as follows, which does NOT involve any premise:

2) TECHNICAL QUESTION: the worrisome side force in the torsional balance experiments, could it be due to the hole on the side of the frustum, producing a side force due to the great waveguide ?

There, fixed for 'ya :)

As Frobnicat agreed, there is no need for the waveguide to enter asymmetrically to produce a side force.  It would still produce a side force (smaller) if entering symmetrically.

EDIT: took "great" out of "great hole" in order to shorten the question and minimize assumptions, in case they used an Iris and they didn't disclose that fact
« Last Edit: 07/28/2015 05:43 PM by Rodal »

Offline TheTraveller

Yang certainly had no issues getting the highest reported thrust to power with a magnetron. Of course you cannot accept all of the magnetron's energy with a high Q, they key seems to be maximizing Q around your frequency of maximum power, and matching a load to accept reflected power.

Based on the 117,500 unloaded high Q work and the Coax feed into the right side, Prof Yang may be moving away from using magnetrons due to the need for low Q (big bandwidth) and having issues with magnetron to cavity bandwidth misalignment causing low Force generation.

What Prof Yang's team has done with impedance matching is clever as it moves the impedance tuning screws from the cavity side wall to the coax to waveguide interface before the iris.
« Last Edit: 07/28/2015 05:42 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 saucyjack

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Perhaps a wiki would be better suited to capture older discussions.

@jknuble - Actually Threads 1 and 2 are available in a more easily-searchable format on the wiki today. I will do the same for this thread as well, once it is locked.

See http://forum.nasaspaceflight.com/index.php?topic=37642.msg1397125#msg1397125 for details.

Offline X_RaY

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@Rodal
1.Thanks for verification (picture Tajmar device yesterday @4,556GHz).
My calculation was verry close :)

2. impressing picture of the fractal antennas... like that
But for what is that good in the frustrum? This type of antenna will be use to get large bandwide, for multiband mobilephones for example. We don't need large BW.
What is need is ~constand impedance match in the possible drift BW if a high Q is recommend like discussed before?
 
3.
"3) We also verified that one cannot excite Transverse Electric (TE) modes with a dipole antenna, regardless of orientation or placement in the truncated cone, the mode excited by a dipole antenna is a Transverse Magnetic (TM) mode."

At the center it doesn't work.

I remember that is possible to get TE resonance with a simple dipole:
(rfmwguy posted something similar / plans for his frustrum...)
 It's most simple for TE01p. At this mode there are currents in Phi vector inside the metallic endplate, the strongest at the radius who the besselfunktion is maximal.
Place a dipole at this radius close to the plate, E-field vector in Phi direction(tangetial to the radius).
The result will be the correct mode if the cone has the correct length to catch that eigenfrequence.

Something similar is possible at the sidewall, one have to activate currents in the right direction for the mode in the wall..
of course one need a full 3D model

very interesting posts today too much to read all after long day full of work  :-[
« Last Edit: 07/28/2015 06:19 PM by X_RaY »

Online Rodal

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....
 
3.
"3) We also verified that one cannot excite Transverse Electric (TE) modes with a dipole antenna, regardless of orientation or placement in the truncated cone, the mode excited by a dipole antenna is a Transverse Magnetic (TM) mode."

At the center it doesn't work.

I remember that is possible to get TE resonance with a simple dipole:
(rfmwguy posted something similar / plans for his frustrum...)
 It's most simple for TE01p. At this mode there are currents in Phi vector inside the metallic endplate, the strongest at the radius who the besselfunktion is maximal.
Place a dipole at this radius close to the plate, E-field vector in Phi direction(tangetial to the radius).
The result will be the correct mode if the cone has the correct length to catch that eigenfrequence.

Something similar is possible at the sidewall, one have to activate currents in the right direction for the mode in the wall..
of course one need a full 3D model

very interesting posts today too much to read all after long day full of work  :-[

aero:  please notice these helpful suggestions.  Perhaps you could try this and see whether it excites TE012 in Yang/Shell

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