Author Topic: EM Drive Developments - related to space flight applications - Thread 2  (Read 2100064 times)

Online dustinthewind

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I still think we can violate newtons 3rd law in a way but in another way it is not violated because the propulsion device projects radiation out one end.  This looks like radiation propulsion but by sticking a dielectric between the two current loops we can change the speed of light making the two current loops closer or lowering the frequency needed while also getting near field effects?  What this does for the radiation projected I'm not exactly sure but I would assume it should intensify.  This is assuming none of the current loops have constant current but are both changing in time and out of phase pi/2 (see figure EM Propulsion 2.png). 


I guess the idea was if there was something similar going on inside the radiation cavity though I can't quite say that there is.  There is also the issue of the idea that radiation projected is conserving momentum but this is inside a cavity.  (see figure EM Propulsion 3.png)

Edit: sorry, changed pi/4 to pi/2
There are many things to discuss here.

Of course  the electric field and magnetic fields are two interrelated aspects of a single object: the electromagnetic field tensor in 3D+1=4 spacetime. 

But if your loops and images are to be interpreted literally only in terms of electric current loops, please notice that your image then could be interpreted as saying that only TE (transverse electric) modes would produce the effect you are seeking, because only TE modes have the electric field in the azimuthal (circumferential) direction.  But notice that NASA Eagleworks is currently successfully testing in a vacuum TM modes (and actually I understand they have a preference for TM modes), for which the magnetic field B has a component only in the azimuthal (circumferential) direction while the electric field E has components perpendicular to the magnetic B field.  The electric field has zero component in the circumferential direction for TM modes.

Oh wow!  I just realized what your saying and after looking at the website, "http://gregegan.customer.netspace.net.au/SCIENCE/Cavity/Cavity.html" TM modes I suspect might also provide propulsion.  If it does exist I suspect it's a relativistic effect.  I didn't want to bring it up as I wanted to first confirm the TM effect would work and hence my quote from my other thread, "If this effect exists (TE) I have another concept that could possibly provide even more propulsion than this but again I am eager to see if even this effect (TM) can be shown to exist. " At the time I didn't understand TE and TM. 

I don't want to just jump up and say that is what this is but it almost looks like the other method I was thinking about.  I am still uncertain of the current phase evolution in the image in time if my assumption on the current in the image is correct.  I do suspect it could provide propulsion in a similar way to TE.  Attached is an image of the gregegan website above and I marked up one of his images (all due respect) to show the current directions which are hopefully accurate.  The currents towards/away from each other are what I suspect could push each other when out of sync by 90 degrees but I don't think it is magnetic for my own reasons.  I'm not certain the effect exists though I suspect it should. 

One thing that bothers me is at the moment I don't think I could explain by the phase concept how the one on the far left could provide propulsion if it does.  ... unless its like a rail gun but I thought they had recoil... unless maybe the phase delay violates the action reaction?  mmm, I don't even know for sure if there is a phase delay is my biggest problem.  Maybe there is a phase delay assuming things are alternating between capacitance then inductance and the radiation has to be injected from a certain direction. 
« Last Edit: 03/28/2015 07:49 PM by dustinthewind »

Offline Stormbringer

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Random silly question:  If Eagleworks can build a torque balance with sufficient sensitivity to measure the current level of thrust above sigma why can't GRC? It seems to me that GRC would have every motive to do so since it would be of more use than the one they have now. They have one now. Therefore they need one. If they need one it stands to reason they would want the most sensitive one they could manage.
« Last Edit: 03/27/2015 04:55 AM by Stormbringer »
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Online Mulletron

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Ok, here's my plan for the way forward:

I have all the data I need now in order to justify moving forward with the unloaded cavity test runs. To accomplish this: I must build the balance and build the Galinstan slip ring for powering the gear riding the balance.

I intend to use the leftover material from the sheet of 1" thick HDPE to construct the slip ring. I will provide photos and drawings of what I have in mind at a later time. For now the concept is still in my head. My 3 day weekend will be devoted to building the slip ring. I have 30grams of Galinstan to play with.

So this weekend.
-Build the slip ring
-Set up the balance
-Integrate everything together.

The slip ring is essentially as follows:
1) 3" diameter HDPE disc with a center hole to hold a small puddle of Ganinstan. Around this hole is a narrow ring, also to hold Galinstan. On the bottom of the HDPE disc, power wires will be run through a groove I mill, and will protrude through drilled/sealed holes into the Galinstan. Around all this a wider channel which will be filled with oil to act as the damper.

2) 3" diameter HDPE disc attached to bottom of the balance at COM/CORotation, with 2 polished and chromed electrodes to pick up power from center hole and ring in other HDPE disc. Power wires will exit from the back of the HDPE disc, through a small hole in the underside of the balance to the topside of the balance.

Next I will fabricate what goes into the oil filled channel of the damper below. I haven't decided what exactly to do with this yet. I want to build a damper system that is adjustable. So that idea is still not settled.

If I can pull this off, the only resistance to rotation on the balance will come from the viscosity of the Galinstan and from the oil damper. If contact is made between the rotating power wires and the HDPE, this will be mitigated by using chromed electrical pickups and the low friction HDPE. Hopefully the Galinstan doesn't corrode the electrical contacts.

Now for the way forward with future loaded cavity testing. I have decided to create a mounting solution for the small end which will support rapidly bolting and unbolting dielectric discs to a heavier sheet of copper, without causing damage. This will use the 3 bolt approach which I learned from Paul March but will be modified in the following way.

On the way is a thicker sheet of 0.043" copper which will be cut to a 6.75" diameter disc. 3 holes will be drilled at 120 degrees, equally spaced. The difference is that, over these holes, I will permanently solder 3, steel nuts and washers to the outside face. Then any dielectric disc will be bolted through from the inside into these nuts. The mounting bolts will be countersunk into the dielectric, in order to provide a smooth interface. The ends of the nuts (on the outside) will be trimmed and covered with conducting copper tape.

Thicker sheet:
http://www.amazon.com/gp/product/B000H9N44I/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1

Bolts: (note the countersinking bolt)
http://www.amazon.com/gp/product/B00NQR0MJI/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1

Challenge to overcome: I am missing one of two lead bricks which were supposed to be control for testing the balance. One arrived in the mail, the other?

Time to build.



« Last Edit: 03/27/2015 10:47 AM by Mulletron »
Challenge your preconceptions, or they will challenge you. - Velik

Offline SpoCk0nd0pe

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Is there any news about the independent verification and validation? It's very hard to find anything reliable on the web :(

Offline Donosauro

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Hopefully the Galinstan doesn't corrode the electrical contacts.

"http://www5vip.inl.gov/technicalpublications/documents/3314568.pdf" says Galinstan pits copper. The Wikipedia page on Galinstan says it corrodes aluminum.

"http://www.rgmd.com/msds/msds.pdf" says it weakens aluminum, and lists a number of other metals that it tends to alloy with, including gold and silver.

Online Rodal

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Is there any news about the independent verification and validation? It's very hard to find anything reliable on the web :(
If you are referring to the paragraph:

Quote from: Brady et.al. Anomalous Thrust Production from an RF Test Device Measured on a Low-Thrust Torsion Pendulum
The current plan is to support an IV&V test campaign at the Glenn Research Center (GRC) using their low thrust torsion pendulum followed by a repeat campaign at the Jet Propulsion Laboratory (JPL) using their low thrust torsion pendulum. The Johns Hopkins University Applied Physics Laboratory has also expressed an interest in performing a Cavendish Balance style test with the IV&V shipset.

I get the impression (from discussion in this thread with Star-Drive and others) that there are NO present plans at the Jet Propulsion Laboratory (JPL) and/or the Johns Hopkins University Applied Physics Laboratory of doing any verification of the NASA Eagleworks tests.

Only Glenn Research Center (GRC) is being considered if (and only if) NASA Eagleworks can give them a drive capable of producing more than 100 microNewtons force in a consistent manner to enable measurements at Glenn Research Center (GRC).  It appears that Glenn Research Center (GRC) does not have the budget and/or interest in modifying their testing device to verify NASA Eagleworks tests at forces lower than 100 microNewtons.

To follow the scientific method, experimental and theoretical results must be replicated by several others in the scientific community for the experimental and theoretical results to be accepted.   Adequate funding and interest are necessary for those experimental replications to take place.

Even if the EM Drive is verified, to enable the crewed space missions to the outer planets proposed by NASA Eagleworks, a political consensus will be necessary to enable the necessary nuclear power for the EM Drive, to make this vision attainable.
« Last Edit: 03/27/2015 04:50 PM by Rodal »

Online Mulletron

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Hopefully the Galinstan doesn't corrode the electrical contacts.

"http://www5vip.inl.gov/technicalpublications/documents/3314568.pdf" says Galinstan pits copper. The Wikipedia page on Galinstan says it corrodes aluminum.

"http://www.rgmd.com/msds/msds.pdf" says it weakens aluminum, and lists a number of other metals that it tends to alloy with, including gold and silver.

Hey good looking out and thanks for the tips!

Progress for today:
https://drive.google.com/folderview?id=0B4PCfHCM1KYoTl90eDBuMklOeTg&usp=sharing&tid=0B4PCfHCM1KYoTXhSUTd5ZDN2WnM

« Last Edit: 03/27/2015 08:32 PM by Mulletron »
Challenge your preconceptions, or they will challenge you. - Velik

Offline zen-in

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On the way is a thicker sheet of 0.043" copper which will be cut to a 6.75" diameter disc. 3 holes will be drilled at 120 degrees, equally spaced. The difference is that, over these holes, I will permanently solder 3, steel nuts and washers to the outside face. Then any dielectric disc will be bolted through from the inside into these nuts. The mounting bolts will be countersunk into the dielectric, in order to provide a smooth interface. The ends of the nuts (on the outside) will be trimmed and covered with conducting copper tape.

Time to build.

You are motivated!   Instead of steel nuts why not use bronze or brass ones?   Bronze hardware is a bit pricey and you would have to find a chandlery (maybe an online store).   It is a lot easier to solder (lead-tin assumed) to bronze or brass,  Steel requires several applications of acid flux to get it fully tinned.   It likely won't make any difference to the internal wave pattern if the nuts are on the outside.   Non-metallic bolts would be needed inside though.   You don't want a couple of resonant antennas.   Have fun!   I own a lathe and mill that I use for my own mad scientist projects.   I would offer you some help but I seem to recall you saying you were in Germany.    Here's a picture of the lathe after I moved it into my garage.  A South Bend 10L made in 1941 and honorably discharged from the Navy.  I have a piece of bronze in the milling adapter.    The mini-mill was a freeby.  I had to order some missing pieces and made the table.
« Last Edit: 03/28/2015 02:44 PM by zen-in »

Offline Flyby

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Just an attempt to see it from another angle or perspective...

So far, the focus of the discussion has been concentrated on the small and big plate of the frustum for receiving the presumed forces generated by the electromagnetic fields, but what is that wasn't the case?

What if the internally generated magnetic field forces interact with the sidewalls instead of the front/back ends?
Because of the angled sides, the internal forces on the sides would be diverted towards the front plate.

Compare it to squeezing  a soap cone: if a circular force is applied from the outside it will move toward the large plate, however if a force is applied from the inside, it will move towards the smaller plate....(just like Shawyer's rotating test rig)
It would also possibly explain to why there is no force detected in a cylindrical cavity.

I have not yet seen any reasoning (maybe i missed it) to why we're all assuming that forces are generated on the front/back end plates - as currently been discussed - and not on the sides walls?

Online Rodal

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Just an attempt to see it from another angle or perspective...

So far, the focus of the discussion has been concentrated on the small and big plate of the frustum for receiving the presumed forces generated by the electromagnetic fields, but what is that wasn't the case?

What if the internally generated magnetic field forces interact with the sidewalls instead of the front/back ends?
Because of the angled sides, the internal forces on the sides would be diverted towards the front plate.

Compare it to squeezing  a soap cone: if a circular force is applied from the outside it will move toward the large plate, however if a force is applied from the inside, it will move towards the smaller plate....(just like Shawyer's rotating test rig)
It would also possibly explain to why there is no force detected in a cylindrical cavity.

I have not yet seen any reasoning (maybe i missed it) to why we're all assuming that forces are generated on the front/back end plates - as currently been discussed - and not on the sides walls?

Thanks for bringing this up as it allows to clarify a few matters.

In my analysis: see for example http://forum.nasaspaceflight.com/index.php?topic=36313.msg1351261#msg1351261 there are no assumptions whatsoever regarding

<<assuming that forces are generated on the front/back end plates - as currently been discussed - and not on the sides walls>>.

As long as they invoke Poynting's vector , there is no such assumption (that forces are generated at the base plates) made at NASA Eagleworks either (either by Dr. White or by Paul March).

As the images in  http://forum.nasaspaceflight.com/index.php?topic=36313.msg1351261#msg1351261
show, the (non self-cancelling component of the) Poynting vector is radially oriented towards the small base of the truncated cone.

Since the components of the electric field E parallel to a copper surface (either the wall or the bases) must be zero at the surface, the Poynting vector component perpendicular  to a copper surface (either the wall or the bases) must be zero at the copper surface  (either the wall or the bases) .

Let me repeat that: the Poynting vector component perpendicular to the small and the big bases of the truncated cone must be zero at those surfaces (must be zero at the small base and must be zero at the big base).

For a Transverse Magnetic (TM) mode the Poynting vector parallel to the surface doesn't have to be zero.  Actually, as the images show, in some cases the maximum Poynting vector occurs at the wall for a TM mode, and for a TM mode the Poynting vector at the wall must be parallel to the wall.


For example:




On the other hand, for Transverse Electric (TE) modes both components of the Poynting vector (parallel to the wall and perpendicular to the wall) must be zero at the copper surfaces (either the wall or the bases) .  For TE modes the Poynting vector is zero at all copper surfaces: zero at the walls and zero at both of the truncated cone bases.

For example, see the Poynting vector component in the radial direction for Transverse Electric mode TE012 for NASA Eagleworks cavity (without a dielectric).  Notice that Poynting's vector is zero at all the surfaces: at walls and at both bases.
« Last Edit: 03/28/2015 11:48 PM by Rodal »

Online Rodal

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Notice that on page 18 of NASA's report "Anomalous Thrust Production from an RF Test Device Measured on a Low-Thrust Torsion Pendulum" (http://www.libertariannews.org/wp-content/uploads/2014/07/AnomalousThrustProductionFromanRFTestDevice-BradyEtAl.pdf ) the authors write:


Quote from: David A. Brady, Harold G. White, Paul March, James T. Lawrence, and Frank J. Davies
There appears to be a clear dependency between thrust magnitude and the presence of some sort of dielectric RF
resonator in the thrust chamber. The geometry, location, and material properties of this resonator must be evaluated using numerous COMSOL iterations to arrive at a viable thruster solution. We performed some very early evaluations without the dielectric resonator (TE012 mode at 2168 MHz, with power levels up to ~30 watts) and measured no significant net thrust.

The readers should not jump to the conclusion that this single experimental evidence means that the EM Drive must work only with a dielectric polymer (like HDPE or PTFE used by NASA).

Examination of the Poynting vector radial component shows that for this particular mode (TE012) without a dielectric, the Poynting's vector is self-cancelling and hence it is not a surprise that NASA measured no thrust force for this TE012 mode without a dielectric, since according to NASA Eagleworks' own theory (relying on Poynting's vector as per Dr. White's papers) there should not be a thrust force without a dielectric for mode TE012 because Poynting's vector self-cancels for this mode.

(Notice that there are two columns of cells, each column having 4 cells in the North-South vertical direction of the truncated cone section.  The columns have left-right symmetry around the central axis, so we only need to refer to one of the columns.

Looking at one column of cells, the upper two cells have Poynting vectors of similar magnitude pointing in different directions:

Uppermost cell: Poynting vector pointing towards small base. Medium Magnitude.
Second cell from the top: Poynting vector pointing towards big base.  Medium Magnitude.

Ditto for the bottom two cells in the same column:

Third cell from the top: Poynting vector pointing towards small base.  High Magnitude.
Fourth cell from the top: Poynting vector pointing towards big base.  High Magnitude.

)

However, for other modes (TM311 for example), Poynting's vector is not self-cancelling, but it is pointed towards the small base.  This justifies the fact that Shawyer communicates that he is presently not using a dielectric, since a dielectric does not appear necessary for certain modes.



@frobnicat: does this experiment (NASA reporting no experimental thrust for TE012 without a dielectric, but reporting thrust force with a dielectric) nullify mechanistic theories such as the one you recently proposed? (or did I miss something that salvages your mechanistic conjecture for this case?)
Of course, electromagnetic artifact explanations that rely on Poynting's vector are still viable, if somebody can come up with such an artifact explanation.


« Last Edit: 03/29/2015 12:54 AM by Rodal »

Offline frobnicat

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...

@frobnicat: does this experiment (NASA reporting no experimental thrust for TE012 without a dielectric, but reporting thrust force with a dielectric) nullify mechanistic theories such as the one you recently proposed? (or did I miss something that salvages your mechanistic conjecture for this case?)
Of course, electromagnetic artifact explanations that rely on Poynting's vector are still viable, if somebody can come up with such an artifact explanation.


Job taking a revenge, don't have much time to explore the consequences of surprising latest precisions by Paul March. For a purely thermal mechanistic theory explaining in part or in whole the signal there is now need to integrate a few facts and data points reported, while some of them could be fragile or fluke as there is not much samples for those cases.

From the point of view of purely thermal mechanistic, on a (even very slightly) tilted pendulum, what is to be explained is not "thrust" but "displacement of LDS reading", remembering that they are not equivalent and that sustained recorded displacements would be induced by sustained shift in position of some part wrt fixation to pendulum arm. That is we would have displacement (vertical axis on charts) proportional to some part(s) position(s), not to first derivative of said position(s) since there is no viscous friction, nor second derivative of said position(s) since the magnitude of recoil effects are too weak and too short lived to play significant role in sustained readings.

In experimental plots, vertical scale varies as a factor from 1m to 5m for same cal pulse of 29.1N. The cal pulse wrt to the scale (apparent total stiffness) is an indirect indicator for the constant that links CoM shift to LDS displacement readings since it gives tilted pendulum component relative to flexure bearings component (components of rest equilibrium restoring torque).  Expect that the more the LDS displaces in m for the same 29.1N (real force), the less the tilted pendulum component, ie. the less the system reacts to CoM's shift.

Few surprising facts and data points for this set of hypothesis :

- That was known from beginning (and always was a difficulty for purely thermal mechanistic) : for some modes there is "no significant net thrust" without dielectric while same mode with dielectric exhibits thrust. This is known for TE012. The absence of thrust without dielectric was for "some very early evaluations", the experimental plot is not published. A TE012 mode with dielectric and thrust is reported in Brady's report. The experimental plot in question, fig. 22 p.18 is unusual in a few respects : the calibrations pulses are 300V and valued at equivalent 60.1N (instead of 200V 29.1N for all other published experiments). The vertical scale in m is absent. The reported "thrust"/power ratio is quite high (compared to other experiments). The rise and fall have a fast component and a slow component, the slow component is very slow (time constant clearly > 30s) and of huge magnitude wrt fast one. Fast component is not fast enough to "ring the bell" the same way the cal. pulses do. All this would hint at "mainly thermal". But then we would expect some comparable thing without dielectric (unless with/without dielectric would alter the mode enough so that heating are quite different). We still haven't seen an experimental plot (and accompanying data) of "no significant net thrust" without dielectric.. Also : apart from TE012 do we know another mode explicitly reported as having no thrust without dielectric and thrust with ? BTW what would be the heating profile for TE012, with and without dielectric ?

- The "turned 180" experiment, with the small end toward right, should report the same thrust profile but in the opposite. It isn't. This would hint at interaction with vacuum chamber walls (the only apparent introduced asymmetry while turning test article 180), that would nullify both thermal mechanistic and EMdrive effects. But the cardboard box experiment tend to show otherwise : metallic walls in the vicinity apparently don't play an important role. There is apparent contradiction. Also the "180" turn experiment was reported as having a dysfunctional RF amplifier (from recollection, anyone can confirm ?) why it is much shorter in duration than usual (?). Would it be possible that this plot is a fluke and not representative ? The idea that pendulum arm is not responsive in the same manner when driven from left to right than the other way around seems quite unlikely : that would mean that the (mechanical) system is behaving in a very far from linear fashion (for instance with solid friction). The cal. pulses are here to show that it is not the case, added on top of a drifting baseline, the same dip is shown whether starting a place or another : quite linear apparently. Another asymmetry introduced by the 180 turn is the position of nylon bolts relative to vertical : for a TM212 (cyl.) the 3 120 spaced bolts that hold dielectric don't bath at same level of microwave heating (because TM212 is not a 120 symmetric mode around axis). If the 180 turn wasn't around Z but around X (as it appear to be from the pictures), a more heated bolt that was above is now below (or the opposite, have to check). Anyway, that could make a difference. And if the "180 turn" plot is to be taken as reliable, this shows that it would make quite a difference. That would hint at a central role of nylon bolts, that are hot enough to melt sometimes, and therefore can be quite often travelling through their glass transition temp. (much lower), with strong nonlinear (wrt Temperature) evolution of Young modulus.

- Last but not least, the "real reversal" by putting dielectric at one end or the other. Note on the plot given with a thrust toward big end (the only plot showing that) that the displacements show a very unusual step-down on top of the dip of "reversed thrust".



The position of LDS reading seems "permanently" changed by a "thrust" pulse. This hints at a remanence. Magnetic ? Maybe. From purely thermal mechanistic hypothesis this looks like permanent plastic deformation or hysteresis remanence. The only other place I see indication for a thrust "in the wrong direction" is in this post where there is question of partial melting of nylon bolts... Again, if some experiment go up to melting, then quite a lot could actually be operating around glass transition and some of them near melting. From this site : we see here that between around 50C and 100C the drop in rigidity is huge, this is much lower than the actual melting (220C). Glass transition is reversible (I think) but may show hysteresis (no ?). How would a nylon bolt under stress (ie. tensioned) behave in length when cycling around the glass transition, would it loosen the fixed dielectric then hold it tight again (against springy slightly warped end PCB plate, we are talking m...) ? 



Don't throw thermal mechanistic through the window. Experimental data can put it to the ground, but through the stairway, one downstep at a time. This post will inevitably raise more questions and objections, this is just ongoing speculations, I won't have time to really support all that in the coming days.
« Last Edit: 03/29/2015 01:03 PM by frobnicat »

Offline Notsosureofit

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FYI

http://www.ebay.com/itm/261252706326?_trksid=p2059210.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

Adding this to the pile as my analyzer only goes to 1GHz.  Thinking of macining off one end for testing dielectrics.

Online Rodal

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....
The position of LDS reading seems "permanently" changed by a "thrust" pulse. This hints at a remanence. Magnetic ? Maybe. From purely thermal mechanistic hypothesis this looks like permanent plastic deformation or hysteresis remanence. The only other place I see indication for a thrust "in the wrong direction" is in this post where there is question of partial melting of nylon bolts... Again, if some experiment go up to melting, then quite a lot could actually be operating around glass transition and some of them near melting. From this site : we see here that between around 50C and 100C the drop in rigidity is huge, this is much lower than the actual melting (220C). Glass transition is reversible (I think) but may show hysteresis (no ?). How would a nylon bolt under stress (ie. tensioned) behave in length when cycling around the glass transition, would it loosen the fixed dielectric then hold it tight again (against springy slightly warped end PCB plate, we are talking m...) ? 



Don't throw thermal mechanistic through the window. Experimental data can put it to the ground, but through the stairway, one downstep at a time. This post will inevitably raise more questions and objections, this is just ongoing speculations, I won't have time to really support all that in the coming days.



So what we have, are two viscoelastic polymers HDPE and Nylon 6.  Both of them suffer from a viscoelastic relaxation at operating temperatures.  You have an excellent point that this calls into question the effectiveness of the Nylon 6 bolts to establish contact between the HDPE and the copper surface, as the amount of compressive stress applied by the Nylon 6 bolts decreases with temperature.

Since the E' modulus of HDPE also decreases with temperature the amount of compressive stress necessary to establish contact decreases with temperature.  As the temperature increases the HDPE dielectric becomes more compliant and hence less stress is necessary to establish contact. But since the E' reduction due to glass transition of the Nylon 6 bolts may be greater, it looks like separation could occur at some higher temperature.  This would be a function of the amount of pre-stress applied on the bolts as well as the temperature experienced during operation.

It would have been better to use a bolt material that does not experience a glass transition temperature in the operating temperature range.  The choice of a polymer bolt that has greater amount of amorphous % than the dielectric is questionable.  Also, the location chosen for the the outer Nylon 6 bolts is non-optimal.  The only optimally located Nylon 6 bolt is the one located at the center.


I mentioned using the following adhesive as an alternative to bolts:

Look at page 51 of this report from Henkel North America (Loctite): http://www.henkelna.com/us/content_data/237471_LT2197_Plastic_Guide_v6_LR7911911.pdf

which are specifically recommended for polyethylene (a very hard to bond polymer)

(Ethyl Cyanoacrylate) Loctite 401 Prism from Amazon:

http://www.amazon.com/Loctite-Instant-Adhesive-Prism-Bottle/dp/B006GOKRSY/ref=pd_sim_sbs_indust_1?ie=UTF8&refRID=14RMFHYMSB2780RR33CY

Use of this primer, Primer for Loctite 401 Prism from Amazon, increases the adhesive shear strength by a factor of 40 times, from 50 psi to 2000 psi  !!!!!:

http://www.amazon.com/Loctite-LOC-18396-770-Cyanoacrylate-Adhesive/dp/B001OBQ8VO/ref=sr_1_fkmr0_1?s=hi&ie=UTF8&qid=1427237585&sr=1-1-fkmr0&keywords=Loctite%C2%AE+770%E2%84%A2+Prism%C2%AE+Primer



The percentage of crystallinity of a polymer depends on many factors including chemical structure, interaction between polymer chains and processing conditions.  This Wikipedia page http://en.wikipedia.org/wiki/Crystallization_of_polymers#Degree_of_crystallinity gives the amounts for some materials of interest:

Nylon 6 (shown in the example above quoted by @frobnicat, which is relevant to the nylon bolts) 35 to 45%
HDPE (used as a dielectric in published NASA Eagleworks tests for the truncated cone) 70 to 80 %
PTFE (used as a dielectric in a few NASA Eagleworks tests) 60 to 80%


Since  only the amorphous part contributes to the glass transition, the glass transition (Tg) for highly crystalline polymers like High Density Polyethylene (HDPE) is weaker than for more amorphous polymers like Nylon 6.

For the dependence of E' (or G') vs. temperature, obtained from DTMA tests, see:

This 1995 article shows a gradual decay from 0 deg C to 120 deg C of E'  for extruded HDPE samples : http://www.unt.edu/LAPOM/publications/pdf%20articles/Boiko95PE.pdf






A minor point: strictly speaking, the ordinate in the example shown above for Nylon 6 and Polycarbonate should be labeled E' (the in--phase viscoelastic "storage modulus" component) , or, if they made the necessary adjustment, E* (the "dynamic modulus") instead of "Elastic Modulus", since the material is viscoelastic



Since these are thermoplastic polymers (as opposed to thermoset polymes like epoxy for example) the amorphous transition is indeed reversible.  There should be some amount of hysteresis due to viscoelasticity, which would be due to the out-of-phase component E" (or due to tan delta  = E"/E' depending on how you express it).

The viscoelastic hysteresis looks like an ellipse (instead of the piecewise hysteresis of elastic-plastic materials).  The area of the ellipse is related to the viscoelastically dissipated power in the polymer.

What kind of hysteresis do you have in mind ?

1) Due to the extremely high frequency (GHz) of the time-dependence of the applied electromagnetic field responsible for heating?

or

2) due to the extremely slow (in comparison) cycling of heating and cooling due to every experiment?

I imagine that your point refers to #2 (the slow cycling of heating and cooling due to every experiment).



I do not recall whether NASA Eagleworks checked the torque on the bolts, with a torque wrench, after every experiment to compare that measurement with the initial torque on the Nylon 6 bolts?

EDIT: If the torque wrench would show that the torque on the Nylon 6 bolts is lower after the test than prior to the test this decrease would be due to viscoelastic deformation of the Nylon 6 bolts due to the higher temperatures experienced during the test.
 
« Last Edit: 03/30/2015 12:22 PM by Rodal »

Offline Damon Hill

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http://www.dtic.mil/dtic/tr/fulltext/u2/a564120.pdf?

"Demonstration of a wingless electromagnetic air vehicle"

Pretty much proof-of-concept, goes into lots more detail than I have endurance to read.

Damon:

Good grief man, this is a great find!!  And an R&D activity I didn't even know was going on.  Now to figure out what is conventional plasma physics and what might be extended EM-Drive physics hiding in this University of Florida paper.

Thanks again,

Best, Paul M.   

As has been pointed out, this isn't a massless drive, of course.  Now that I'm thinking about it, this may simply be a basis for a useful type of thruster of some sort, but it also could be a caveat about unintended side effects of a strong RF field over a conductive surface that generates some tiny amount of thrust in an atmosphere.  On the opposite side of the surface, even.  That might lead to measurement errors.

In and of itself, the propulsion principle apparently demonstrated might lead somewhere, or not.  I should live so long to see it levitate something of serious mass, or an orbiting RF resonant cavity raise its orbit.  Maybe tack against the solar wind?

Mainly I was hoping this paper might contain some useful clues to someone.  Propulsion without moving parts or mass of any sort is slightly spooky to me.  For that matter, so is a Peltier cell, and I own one of those.

--Damon

Offline frobnicat

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...

...

What kind of hysteresis do you have in mind ? Due to the extremely high frequency (GHz) of the time-dependence of the applied electromagnetic field responsible for heating? Or due to the extremely slow (in comparison) cycling of heating and cooling due to every experiment?

Slow cycling of heating and cooling. Also note that the nylon bolts, at equivalent local EM excitation conditions (smoothed as "DC" heat flow with much higher time constant than ns) seem to swallow much more microwave than copper/hdpe/ptfe. Typical overall temperatures raises (from initial ambient) actually measured (from the outside) are an order of magnitude below the temperature of nylon fusing, yet it has been shown experimentally that some part of nylon bolts at the small end was heated enough to melt, in spite of the AC EM fields amplitude being low in the small end. Could it be due to the water content of nylon ?





This later is for "nylon 6 pellets" exposed to air, from this page, don't know exactly the characteristic size of pellets for injection-molding, same order of magnitude as the bolts ?
 
What would be the effect of vacuum, compared to in air at usual lab ambient humidity ? Vacuum conditions would likely degas the water content of nylon, depending on the time during which nylon bolts are in vacuum they would  be dryer than when in air. Do the water absorbed in nylon couple to microwave heating as bulk water does ?

Questions here : is it because of water content that nylon seems to heat a lot in the frustum (compared to other parts) ? And if yes, what would be the difference in microwave heating when in vacuum due to water content degasing, depending on vacuum conditions duration ? That could explain the difference in magnitude of the effects in vacuum relative to in air (not jumping to conclusions here, this would just be a fact compatible with conjecture). Also, what would be the complete stress response material history when mounting and tensioning the bolts in air with some water content, evacuating (drying the bolts), heating above glass transition, cooling below glass transition, cycling around glass transition a few times.

What is interesting from a thermal mechanical viewpoint with the nylon bolts is twofold :
- the temperature would be an order of magnitude higher the other temperature raises, that also means that the apparent time constant are much lower, in the seconds rather than 10s of seconds (how long would it take a nylon bolt at 100C to cool below 50C at power off ?)
- the nonlinearity of glass transition makes for a nice plateau : this plateau would translate in the plots (while just considering temperature one sees ramps more than plateaus)

I was sure that your knowledge of polymers would prove useful to polish this line of reasoning  :)
Unfortunately, as I said, paid job leaves me little spare time those days... bookmarking your precisions for later use.

Online Rodal

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....

Few surprising facts and data points for this set of hypothesis :

- That was known from beginning (and always was a difficulty for purely thermal mechanistic) : for some modes there is "no significant net thrust" without dielectric while same mode with dielectric exhibits thrust. This is known for TE012. The absence of thrust without dielectric was for "some very early evaluations", the experimental plot is not published. A TE012 mode with dielectric and thrust is reported in Brady's report.....

What is new is the reporting of Poynting vector plots, to show the Poynting vector field for different modes and their significance.

http://forum.nasaspaceflight.com/index.php?topic=36313.msg1352243#msg1352243

http://forum.nasaspaceflight.com/index.php?topic=36313.msg1352368#msg1352368

Although Dr. White published several papers predicting that the force on the EM Drive would depend on the Poynting vector, for example,

Quote from: p.10 of Brady  et.al.'s  "Anomalous Thrust Production from an RF Test Device Measured on a Low-Thrust Torsion Pendulum"
Consideration of the dynamic fields in the wave resonance tube shows that there is always a net Poynting vector meaning that the RF launcher tube assembly with dielectric cylinder common to both the slotted and smooth test articles is potentially a Q-thruster where the pillbox is simply a matching network.

I have not seen any published calculations by Dr. White and his group of the Poynting vector field for the EM Drive. There are no Poynting vector plots shown in the paper "Anomalous Thrust Production from an RF Test Device Measured on a Low-Thrust Torsion Pendulum" by Brady et.al. and there have been no Poynting vector plots shown by Paul March in our threads either.

The Poynting vector (its divergence and its vorticity) plays a prominent role in Dr. John Brandenburg's paper (see attachment to http://forum.nasaspaceflight.com/index.php?topic=36313.msg1349142#msg1349142 ) but again, there is no computation and plots of the Poynting vector field for the truncated cone for different electromagnetic modes.

Shawyer has not published any Poynting vector calculations either. 

Prof. Juan Yang and her colleagues mention the Poynting vector in their calculations, but I have not seen any plots of the Poynting vector field reported in Prof. Juan Yang's papers either.

Greg Egan did not publish any plots of the Poynting vector field either, in his article:  http://gregegan.customer.netspace.net.au/SCIENCE/Cavity/Cavity.html

Consideration of the boundary conditions for the Poynting vector seem to also have not been mentioned in the published literature of the EM Drive.

I have not seen the following previously mentioned in any EM Drive report:

Quote
Since the components of the electric field E parallel to a copper surface (either the wall or the bases) must be zero at the surface, the Poynting vector component perpendicular  to a copper surface (either the wall or the bases) must be zero at the copper surface  (either the wall or the bases) .

Let me repeat that: the Poynting vector component perpendicular to the small and the big bases of the truncated cone must be zero at those surfaces (must be zero at the small base and must be zero at the big base).

For a Transverse Magnetic (TM) mode the Poynting vector parallel to the surface doesn't have to be zero.  Actually, as the images show, in some cases the maximum Poynting vector occurs at the wall for a TM mode, and for a TM mode the Poynting vector at the wall must be parallel to the wall.

On the other hand, for Transverse Electric (TE) modes both components of the Poynting vector (parallel to the wall and perpendicular to the wall) must be zero at the copper surfaces (either the wall or the bases) .  For TE modes the Poynting vector is zero at all copper surfaces: zero at the walls and zero at both of the truncated cone bases.


The following points do not appear to have been previously made either:

Quote from: Rodal
Examination of the Poynting vector radial component shows that for this particular mode (TE012) without a dielectric, the Poynting's vector is self-cancelling and hence it is not a surprise that NASA measured no thrust force for this TE012 mode without a dielectric, since according to NASA Eagleworks' own theory (relying on Poynting's vector as per Dr. White's papers) there should not be a thrust force without a dielectric for mode TE012 because Poynting's vector self-cancels for this mode.

....
However, for other modes (TM311 for example), Poynting's vector is not self-cancelling, but it is pointed towards the small base.  This justifies the fact that Shawyer communicates that he is presently not using a dielectric, since a dielectric does not appear necessary for certain modes.

Actually, Prof. Yang writes the complete opposite conclusion (http://www.emdrive.com/NWPU2010translation.pdf ):

Quote from: Yang Juan,Yang Le,Zhu Yu,Ma Nan
Using finite element numerical method to numerical analyse the classical Maxwell equation of electric field of the idealised conical resonator, to obtain the model and practical of the distribution of the electric field of the cavity under 1000W. By analyse the properties under different modes and the different properties. Calculation show that under the four modes, TE011, TE012, TE111 and TM011, the quality factor of TE012 is highest and with highest thrust, followed by TE011. With the Small End of the cavity unchanged, the quality factor and thrust decrease with the increase in the Large End

Prof. Juan Yang writes that her Finite Element calculations show mode TE012 as having the highest thrust (without dielectric).  My exact solution calculations show that the Poynting vector fields are self cancelling for TE012 without dielectric.

Furthermore NASA Eagleworks experiments confirm the self-cancellation of the Poynting vector field for mode TE012: NASA, using the truncated cone without dielectric, and excited at the TE012 frequency, "measured NO significant net thrust": the complete opposite of Prof. Juan Yang's conclusion, but in full accordance with my calculations of the Poynting vector distribution for mode TE012.
« Last Edit: 03/30/2015 01:31 PM by Rodal »

Online Mulletron

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Galinstan slipring prototype constructed:

I milled out the sheet of 1" thick HDPE mostly by hand. I had the aid of a Dewalt hand drill and a Dremel type of tool.

30 grams Galinstan was exactly enough. The center Galinstan channel is 8mm deep and 16mm wide. The center channel is shaped inside like an inverted cone. This will aid in maintaining center.

The ring Galinstan channel is 8mm deep/6mm wide which is plenty and gives me room to adjust so the 3mm wide contacts don't touch anything but the liquid metal. Attached are photos showing open circuit, short circuit.

The Galinstan channel side walls and bottom are smooth. The oil damper channel side walls are smooth, but the bottom was left lumpy for now. I might just keep it that way. I'm torn on whether the effort to smooth out the bottom might take away the useful turbulence I could get from that lumpy bottom of the channel.

I'm keeping the Galinstan in the slipring from now on to make sure it will remain stable. Tolerances between the penetrating wires and the holes through the HDPE are extremely tight so I expect no leaks just on account of that. I took the extra measure of sealing the bottom and top of the holes with hot glue, then sandwiched a like bottom plate over the wires, further sealed by hot glue.

The wires are flush with the bottom of the Galinstan channel. Approximately 4mm of HDPE was milled out around the tops of the wire holes to allow liquid metal to make maximum contact with the copper wires.

Also attached are pics of balance overview and zoomed in shot. In the zoomed in shot, those wires will be cut to length and terminated with chromed contacts.

The damper fins/blades haven't been built yet. Should be pretty easy to pull off. The oil damper channel is 20mm wide with 10mm useful depth.

Next up is to hang it, energize it and see what systemic effects this approach causes. I can do AC or DC with this. If it works out, then great. If it don't work out (like it becomes a motor), I'll fly a battery.

Starting to feel like I'm finally making some progress on this.

Rest here:
https://drive.google.com/folderview?id=0B4PCfHCM1KYoTl90eDBuMklOeTg&usp=sharing&tid=0B4PCfHCM1KYoTXhSUTd5ZDN2WnM
Challenge your preconceptions, or they will challenge you. - Velik

Offline MazonDel

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Mulletron: I'm not too aware of the electrical properties of Galinstan and I might just be misinterpreting your wording, but if the bottom of the channel that the Galinstan is contained in is rough enough to have 'significant' height variance couldn't this cause possible issues for the cleanliness of your signal through it? A bit like using a potentiometer as a wire as the changing depth of the Galinstan would thus result in changing resistance over its length. So as your contact in the Galinstan moved across the channel, the changing resistance would add noise to it. I don't know how rough the surface is or if the noise in question is outside the realm of your tolerances, but I figured I should mention it.

Edit: It also occurs to me, that if you do want that roughness on the bottom as you mentioned, you should be able to use some filters on the rig to clean up the noise if you need to.
« Last Edit: 03/30/2015 03:28 PM by MazonDel »

Online Mulletron

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Mulletron: I'm not too aware of the electrical properties of Galinstan and I might just be misinterpreting your wording, but if the bottom of the channel that the Galinstan is contained in is rough enough to have 'significant' height variance couldn't this cause possible issues for the cleanliness of your signal through it? A bit like using a potentiometer as a wire as the changing depth of the Galinstan would thus result in changing resistance over its length. So as your contact in the Galinstan moved across the channel, the changing resistance would add noise to it. I don't know how rough the surface is or if the noise in question is outside the realm of your tolerances, but I figured I should mention it.

Edit: It also occurs to me, that if you do want that roughness on the bottom as you mentioned, you should be able to use some filters on the rig to clean up the noise if you need to.

Hi and welcome. The Galinstan channels are smooth and consistent with respect to depth and width. This was by design.


The Galinstan channel side walls and bottom are smooth.

Galinstan is recommended as a safer alternative to mercury in applications such as this due to its liquid metal behavior at room temperature and excellent electrical properties. I tested the resistance of Galinstan with my meter and found it performs as well as a wire. See pics above.

Electrical conductivity: 3.46x106 S/m (from the Oracle) http://en.wikipedia.org/wiki/Galinstan#cite_note-scitoys-3

Quote
A bit like using a potentiometer as a wire as the changing depth of the Galinstan would thus result in changing resistance over its length. So as your contact in the Galinstan moved across the channel, the changing resistance would add noise to it.

As far as the potentiometer reference. You can use a VERY long length of wire to make a pot, as even copper wire or Galinstan is considered a conductor, still has resistance. The resistance measured between 1mm or 1cm of wire or Galinstan is negligible. You can't even see it on the meter. Normally the resistive element for a potentiometer is graphite, or some other resistor. You can use wire, but you needs boat loads of wire in a coil.

I'm using this setup to couple power across a moving gap, like what you would find in a radar for power/status in the antenna. For the purposes intended, signal noise makes no difference to me. The power contacts which I have pictured are rated for 240VAC 15amps, and I am able to completely able to submerge the contacts in the liquid and not make contact with the bottom or the edges.

I only need 6VDC, 2 amps.

If I wanted to, I could literally run a space heater using this.

I'm prepared/equipped for both AC and DC. I have a 12VDC 15A power supply I use for my LIPO charger. I'm going to try AC first. I'm comfortable with (but still respect) high voltage.

I tested this with a meter and found no issues. I'll let you know if I encounter problems, the reason why, and if there is a fix/work around.

I'm more worried about spilling the liquid metal and/or bumping it and creating a short circuit. So I will develop protocols to ensure I don't have any accidents as this stuff is $90 for 30grams.

For others out there who don't want to use Galinstan, yet want to attempt a replication, there are numerous sliprings on Ebay which use carbon brushes, but as this balance is designed to measure very small forces, I opted to use Galinstan. When I get around to the Cavendish experiment, I'll know how sensitive the balance actually will be.

« Last Edit: 03/30/2015 07:15 PM by Mulletron »
Challenge your preconceptions, or they will challenge you. - Velik

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