Author Topic: EM Drive Developments Thread 1  (Read 765251 times)

Offline JohnFornaro

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Re: EM Drive Developments
« Reply #2840 on: 11/01/2014 02:52 AM »
Sorry for asking, but -as the discussion is getting very technical- could someone of you make a quick update for the non-physicists among us (like myself)? is there any tangible progress, or has the device been demistified once for all?

thanks! :)

Francesco, we are getting close to showing, analytically, that the EM Drives test results are likely an experimental artifact.

Sorry for asking, but -as the discussion is getting very technical- could someone of you make a quick update for the non-physicists among us (like myself)? is there any tangible progress, or has the device been demistified once for all?

thanks! :)

Hi there.

I wouldn't put much stock in the ostensibly technical speculations that fill this thread. The results are certainly wrong and are in clear violations of macroscopic conservation of momentum. All explanations or "models" proposed to explain this (quantum plasma, virtual particles, etc.) are all based on incredibly bad physics.

Any signal these experimenters find is almost certainly due to a terrible experimental method and questionable data analysis.

As far as I can tell, along with the greater physics and engineering communities (from what I have seen), this is a fantasy device.

SuperG:  You either need to brush up on reading comprehension, or yuo need to brush up on saying exactly what you mean.

Francesco asked a reasonable question, and  Jose answered it, saying, "the EM Drives test results are likely an experimental artifact".  You go on to say that these results are "certainly wrong".  In other words, since Jose must be "certainly wrong", the results are not an experimental artifact and must therefore be real.  Then you go on to contradict yourself and assert that it is a "fantasy device".

Again, just decide what you want to say.  And then say it.  You cannot claim both sides of the discussion as your truth.

Sometimes I just flat out don't get it.

Online ThinkerX

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Re: EM Drive Developments
« Reply #2841 on: 11/01/2014 03:34 AM »
Quote
Sorry for asking, but -as the discussion is getting very technical- could someone of you make a quick update for the non-physicists among us (like myself)? is there any tangible progress, or has the device been demistified once for all?

Fascinated member of the peanut gallery here.  I can take a shot at the highlights covered over the past 100 or so pages in this thread, though it may not be entirely accurate.

When Doctor Rodal first posted in this thread, he was of the view the reported results were an experimental artifact, most likely thermal in nature.  After a post by a member of the Eagleworks team casting doubt on this assumption, he and the other regular posters here began looking for alternatives, especially experimental artifacts.  Contrary to what 'Supergravity' posted, the explanations for the devices performances were seen by the brainier types here to be flawed from the outset.

A number of reasonably rational scientific explanations were considered should all the experimental artifacts be ruled out.  Of these, few showed any promise:

1) The device was somehow pushing against 'Dark Matter.'  This might be valid, if one accepts a very high estimate for the local abundance of Dark Matter.  But still dubious. 

2) Ion Wind devices, using the Bifield - Brown effect.  This is a real effect, used by...hobbyist...to make pure electrical flying devices.  Search for 'Anti-Gravity' in You-Tube sometime to see videos of these devices in action.  Ultimately, this was ruled out because of the very low power levels involved.

3) Unruh Radiation, which is a sort of 'inertia radiation', which is an element in a branch of physics attempting to make General Relativity and Quantum Mechanics play well together.  It also negates many of the more dubious elements theorists have conjured to explain observed astronomical reality - things like dark matter and dark energy.  A professor McCulloch has been promoting this on his blog, which is occasionally linked to in this thread.  So...   

http://physicsfromtheedge.blogspot.com/

Many of the last few dozen pages have been dedicated to gathering enough info about the various EM devices tested to run 'back of the envelope' calculations as to whether or not Unruh Radiation is a viable solution.  Results have been mixed, in no small part because even basic information about these devices - like their size and proportions - is very difficult to come by.  Additionally, this explanation is very frequency dependent, and worse, the frequency shifts.  The experimenters are essentially blundering about in the dark, hitting the correct frequency by occasional accident.   Unruh Radiation is still considered a possibility, and I believe several members here find the theory of great interest even if they doubt the EM Drive is somehow tapping into it.  Which brings us to where matters stand now:

The experimenters are demonstrating an across the board failure to understand certain 'stress forces' which have a high possibility of giving at least partial false results in their experiments.  Furthermore, the explanatory equations put forth by both Doctor White and Shawyer have errors within them.  Which means the results may be false positives - the EM Drive does not work.

That said, the notion of tapping into Unruh Radiation and using it to propel a starship is interesting in its own right.

And even if Unruh Radiation does not exist, some force, currently termed 'Dark Energy' exerts enough force on space-time to drive galaxies apart at a continuous 1 kilometer per second per kilo parsec. 

(I hope I didn't get too many things wrong here.)




Offline Mulletron

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Re: EM Drive Developments
« Reply #2842 on: 11/01/2014 07:38 AM »
Did I mention that every time someone mentions Unruh Radiation and Emdrive in the same sentence, a cute bunny gets it? Seriously though, a kid reading this forum is going to have his/her ideas about science all jacked up because of the enduring false info that keeps being perpetuated around here because it is popular, or some PhD sponsors it. I know back when I was a little feller, I ate this space and physics stuff up as fast as I could get my hands on it. I'm lucky internet forums weren't around back then.

A photon doesn't experience Unruh Radiation. Accelerate a massive object toward C and it might experience Unruh Radiation (if it exists). A photon is simply a disturbance in the electromagnetic field that propagates at C. The photon is the force carrier of that disturbance. It doesn't accelerate to get to C. It is always at C.

Is anything I'm posting here being taken seriously? I'm not making this stuff up. I get the sense that the truths I speak here are being blackballed in favor of fantasy or popular opinion which aren't even close to science. Um, science isn't democratic and opinion doesn't matter. Just the facts matter.

We were probably on the right track with modified inertia, but a monster got created out of it. Light doesn't even have inertia. You can't modify the inertia of light. Light has momentum, but not inertia. You can modify the inertia of all the other stuff which has mass inside that copper can, but not the RF. Leave light alone and start applying MiHsC in the right direction, to the particles in the copper can which actually have inertia. It is being applied bass ackwards right now. Then lets hope that copper cans can actually modify inertia a little bit in the first place. We're already on thin ice trying to mess with inertia.

The whole reason modified inertia came into being in this forum is directly from the factual knowledge that the symmetry of space directly informs our conservation laws, and that the asymmetry of the copper cavity may very very slightly modify that symmetry of space, thus possibly allowing an inertial bias of the matter (dielectric/air) within the cavity. Not the rf. Don't believe me? Look back in time in this thread and see when I starting going on about inertia.

Later it was discovered that the asymmetry of the cavity wasn't even needed/nor was modified inertia, because of new information found regarding the behavior of chiral dielectrics.

So that whole MiHsC can of worms, which required messing with EEP right here on Earth, wasn't needed anymore. That is a good thing for the sake of the theory. MiHsC could be returned to the realm of low accelerations at galactic scales where it belonged. MiHsC is no less important. It simply isn't useful here on Earth. I'd hate to see the rest of the scientific world poo poo a perfectly good theory because it was applied too broadly and lost credibility. Especially if it is applied incorrectly to light.

Well anyway I'm not here to be popular. I'm here to look at the facts and use all available information to figure things out. All while not tricking myself or pushing I believe buttons.

If the above doesn't apply to you, please disregard.

If I got my science wrong, please correct me. I've gotten things wrong before and have no problem changing my views given new/better information.

Respectfully,
Mulletron
« Last Edit: 11/01/2014 11:35 AM by Mulletron »
Challenge your preconceptions, or they will challenge you. - Velik

Offline Notsosureofit

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Re: EM Drive Developments
« Reply #2843 on: 11/01/2014 01:08 PM »
Just a quick update on looking at GR:  Can't find an inertial hook.  The cavity would have to modify the frequency to give an AFR.  Don't see any mechanism yet......still looking.

Offline JohnFornaro

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Re: EM Drive Developments
« Reply #2844 on: 11/01/2014 01:27 PM »
Fascinated member of the peanut gallery here. Peanut crop was good this year, eh?

I can take a shot at the highlights covered over the past 100 or so pages in this thread ....

... Rodal ... was of the view the reported results were an experimental artifact, most likely thermal in nature.  After a post ... he and the other regular posters here began looking for alternatives, especially experimental artifacts.  ... the explanations for the device's performances were seen ... to be flawed from the outset.

A number of reasonably rational scientific explanations were considered should all the experimental artifacts be ruled out.  Of these, few showed any promise:

1) The device was somehow pushing against hypothetical
 'Dark Matter.' This might be valid, if one accepts a very high estimate for the local abundance of Dark Matter,  which stell needs to be found.  But still dubious. 

2) Ion Wind devices, using the Bifield - Brown effect.  This is a real effect, used by...hobbyist...to make pure electrical flying devices.  ... this was ruled out because of the very low power levels involved and because it needs atmosphere of a higher density than space to create ions out of.

3) Unruh Radiation, which is a sort of 'inertia radiation', which is an element in a branch of physics attempting to make General Relativity and Quantum Mechanics play well together, and which is also sort of hypothetical.  [Unruh radiation] also negates many of the more dubious elements theorists have conjured to explain observed astronomical reality - things like dark matter and dark energy.  A professor McCulloch has been promoting this on his blog, which is occasionally linked to in this thread.  So...   

http://physicsfromtheedge.blogspot.com/

Many of the last few dozen pages have been dedicated to gathering enough info about the various EM devices tested to run 'back of the envelope' calculations as to whether or not Unruh Radiation is a viable solution.  Results have been mixed, in no small part because even basic information about these devices - like their size and proportions - is color=blue]unnecessarily[/color] very difficult to come by thru no fault of the thread's theorists.  Additionally, this explanation is very frequency dependent, and worse, the frequency shifts.  The experimenters are essentially blundering about in the dark, hitting the correct frequency by occasional accident.   Unruh Radiation is still considered a possibility, and I believe several members here find the theory of great interest even if they doubt the EM Drive is somehow tapping into it.  Which brings us to where matters stand now:

The experimenters are demonstrating an across the board failure to understand certain 'stress forces' which have a high possibility of giving at least partial false results in their experiments.  The "across the board failure" is particularly troublesome, since there is no good reason for that failure.  Furthermore, the explanatory equations put forth by both Doctor White and Shawyer have errors within them.  Which means the results may be false positives - the EM Drive does not work.

That said, the notion of tapping into Unruh Radiation and using it to propel a starship is interesting in its own right.

And even if Unruh Radiation does not exist, some force, currently termed 'Dark Energy' exerts enough force on space-time to drive galaxies apart at a continuous 1 kilometer per second per kilo parsec. 

(I hope I didn't get too many things wrong here.)

I just added a few blue remarks as I talked to the screen.
Sometimes I just flat out don't get it.

Online Rodal

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Re: EM Drive Developments
« Reply #2845 on: 11/01/2014 01:32 PM »
I expanded the photo as big as it will go, and slowed my mouse as slow as it will go to take out my hand shake, and picked off a 5 pixel width of the big end edge. At that scale the 3.81 cm Frzl? beam end was 110 pixels but close to the same distance from the camera.

Five pixels at that scale comes out to be 0.173 cm, or 1/16". But there is the question as to just what I measured because the ends of the cavity seem to be a board of some sort, and not all copper.

What are you trying to do? I guess you want to see if the vibration comes from flexing of the thin copper. But at a GHz, that seems unlikely. Better to analyze than guess, though. But if the end is a copper covered board, as has been suggested, what would be the density of that? And what would be the likelihood of the copper covering vibrating independently of the board? Coming loose, so to speak.

Thank you, aero, for this very comprehensive view at the copper thickness, with the conclusion that the copper seems to be thinner than 1/16".

I am looking at thermoelastic coupling to explain the initial impulse part of the response.  Thermoelastic coupling is usually neglected in the equations of thermoelasticity.

Taking:

thermal diffusivity = 1.11 * 10^(-4) m/s
poisson's ratio = 0.3
E = 117 GPa
density = 8940 kg/m^3
Length = 0.25 m (latest length estimate for truncated cone length from aero)

I get that the thickness of copper would have to be less than 0.073 inches for coupling effects to be important so that inertial terms due to temperature would appear.  For copper thickness = 0.029 in or less, the inertial terms are such that the dynamic magnification factor are quite significant.  For that thinness of copper one gets (due to classical physics) what essentially are thermal waves in the initial part of the response.

So the initial impulse would be a result of inertia due to thermoelastic coupling, and the later decaying exponential rise would be explained as per frobnicat.  Both effects are entirely classical.
« Last Edit: 11/01/2014 01:44 PM by Rodal »

Online Rodal

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Re: EM Drive Developments
« Reply #2846 on: 11/01/2014 01:37 PM »
To explain the impulse part of the response,

I need to have an independent estimate of the copper thickness in these devices.


could anyone please provide a guesstimate or a range for what the thickness of the copper in these EM drives maybe ?

I am also interested in the thickness of the NASA test article. Shawyer and the Chinese I don't care about because of my lack of confidence in their reporting. It is important to my evanescent wave coupling hypothesis; in the quest for yet another plausible artifact to explain away reports of thrust from an empty copper can under high power. I've been getting indications and warnings of 1/8" thickness, but I cannot confirm with high confidence.

I expect the cavities were made of some commonly available copper sheet. I doubt that Eagleworks did anything more difficult than go to the hardware store and buy a sheet of copper. Here is a web site that sells copper sheet. Look at the choices and take your pick. Or find your own favorite copper sheet retailer. Or call your local hardware store and ask them what thicknesses they have in stock. But from looking at the photo I can't tell, the resolution isn't good enough.


The cone looks like it was made from 20 gauge or thinner copper, possibly the same material roofers use.  You sometimes see trucks with a big spool of it on the back.   1/8" Thick copper would require machine tools like a metal press to form.  Even 1/16" thick copper (14 gauge is the closest) requires a lot of work to form into a cone and the tool marks would show.   Also the weight would be an issue.  I think it is most likely 20 to 26 gauge (.032" - .016").   Building an apparatus like the eagleworks em-drive would not be difficult.   Just a few large pieces of FR4, some lightweight Copper sheets and a jig for forming it into the cone shape.   

Thank you zen-in for this very practical view at the fact that the copper thickness seems to be much thinner than the 1/8 in suggested by Mlltrn.  That suits my calculations just fine.

I am looking at thermoelastic coupling to explain the initial impulse part of the response.  Thermoelastic coupling is usually neglected in the equations of thermoelasticity.

Taking:

thermal diffusivity = 1.11 * 10^(-4) m/s
poisson's ratio = 0.3
E = 117 GPa
density = 8940 kg/m^3
Length = 0.25 m (latest length estimate for truncated cone length from aero)

I get that the thickness of copper would have to be less than 0.073 inches for coupling effects to be important so that inertial terms due to temperature would appear.  For copper thickness = 0.029 in or less, the inertial terms are such that the dynamic magnification factor are quite significant.  For that thinness of copper one gets (due to classical physics) what essentially are thermal waves in the initial part of the response.
« Last Edit: 11/01/2014 01:39 PM by Rodal »

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Re: EM Drive Developments
« Reply #2847 on: 11/01/2014 01:57 PM »
The coupling coefficient (basically due to the strain rate being larger than the temperature rate) is non-trivial.  But calculating the Fourier non-dimensional time is trivial, so let's calculate the time for which the Fourier non-dimensional = 1, which is simply ((thickness)^2)/thermalDiffusivity


thermalDiffusivity = 1.11*10^(-4) m/s

so for thickness of copper = 1/8 in = 0.00318 m
hence time = 0.0908 s

so for thickness of copper = 1/16 in = 0.00159 m
hence time = 0.0227 s

so for thickness of copper = 0.022 in = 0.000559 m
hence time = 0.0028 s

So, the initial thermal effect on the copper thickness is clearly impulsive, from the point of view of the much slower response of the inverted torsional pendulum (with period ~ 4.5 s as provided by Paul March himself, or 4.8 s as measured by frobnicat, and both of them corroborated by my analytical model of the inverted torsional pendulum)
« Last Edit: 11/01/2014 02:04 PM by Rodal »

Offline Notsosureofit

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Re: EM Drive Developments
« Reply #2848 on: 11/01/2014 02:01 PM »
The coupling coefficient is non-trivial.  But calculating the Fourier non-dimensional time is trivial, so let's calculate the time for which the Fourier non-dimensional = 1, which is simply ((thickness)^2)/thermalDiffusivity


thermalDiffusivity = 1.11*10^(-4) m/s

so for thickness of copper = 1/8 in = 0.00318 m
hence time = 0.0908 s

so for thickness of copper = 1/16 in = 0.00159 m
hence time = 0.0227 s

so for thickness of copper = 0.022 in = 0.000559 m
hence time = 0.0028 s

So, the initial thermal effect on the copper thickness is clearly impulsive, from the point of view of the much slower response of the inverted torsional pendulum (with period ~ 4.5 s)

Great!  Look at the drumhead expansion of the big end .002" copper FRP w/ resistve heating from the Cu loss!

http://en.wikipedia.org/wiki/FR-4
« Last Edit: 11/01/2014 02:10 PM by Notsosureofit »

Online Rodal

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Re: EM Drive Developments
« Reply #2849 on: 11/01/2014 03:08 PM »
The coupling coefficient is non-trivial.  But calculating the Fourier non-dimensional time is trivial, so let's calculate the time for which the Fourier non-dimensional = 1, which is simply ((thickness)^2)/thermalDiffusivity


thermalDiffusivity = 1.11*10^(-4) m/s

so for thickness of copper = 1/8 in = 0.00318 m
hence time = 0.0908 s

so for thickness of copper = 1/16 in = 0.00159 m
hence time = 0.0227 s

so for thickness of copper = 0.022 in = 0.000559 m
hence time = 0.0028 s

So, the initial thermal effect on the copper thickness is clearly impulsive, from the point of view of the much slower response of the inverted torsional pendulum (with period ~ 4.5 s)

Great!  Look at the drumhead expansion of the big end .002" copper FRP w/ resistve heating from the Cu loss!

http://en.wikipedia.org/wiki/FR-4

I need to know the boundary conditions for the 0.002" copper.

Is the 0.002" copper a separate thin sheet of copper, or is the 0.002" copper thermally sprayed on the fiber-reinforced-polymer substrate and hence integrally bonded to it, or is the 0.002" copper adhered to the fiber-reinforced-polymer substrate ?

Can the 0.002" be easily peeled apart from the polymer composite substrate?
(Can one hold on to that 0.002" copper with pliers and peel it apart from the polymer composite substrate?
« Last Edit: 11/01/2014 03:15 PM by Rodal »

Offline Notsosureofit

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Re: EM Drive Developments
« Reply #2850 on: 11/01/2014 03:12 PM »
Yes, it's adhesive bonded.

Offline aero

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Re: EM Drive Developments
« Reply #2851 on: 11/01/2014 04:41 PM »
Does the label on the end of the cavity material mean anything to anyone?

As I read it, it is "1605Mg" but even blown up as large as it will go, it is hard to tell for sure.
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Online Rodal

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Re: EM Drive Developments
« Reply #2852 on: 11/01/2014 08:43 PM »
The coupling coefficient (basically due to the strain rate being larger than the temperature rate) is non-trivial.  But calculating the Fourier non-dimensional time is trivial, so let's calculate the time for which the Fourier non-dimensional = 1, which is simply ((thickness)^2)/thermalDiffusivity


thermalDiffusivity = 1.11*10^(-4) m/s

so for thickness of copper = 1/8 in = 0.00318 m
hence time = 0.0908 s

so for thickness of copper = 1/16 in = 0.00159 m
hence time = 0.0227 s

so for thickness of copper = 0.022 in = 0.000559 m
hence time = 0.0028 s

So, the initial thermal effect on the copper thickness is clearly impulsive, from the point of view of the much slower response of the inverted torsional pendulum (with period ~ 4.5 s as provided by Paul March himself, or 4.8 s as measured by frobnicat, and both of them corroborated by my analytical model of the inverted torsional pendulum)
Another trivial thing we can do is to compute the mechanical characteristic times for wave propagation (as compared to thermal characteristic times given by Fourier's number), to confirm that they are much smaller than the thermal time.  In fact they are about 1000 times smaller.

Velocity of propagation of Lamb bending waves in a thin plate = vL = Sqrt [E/(rho*(1-nu^2)) ]

(for wavelengths larger than the thickness of the plate, otherwise for wavelengths smaller than the thickness of the plate the velocity of propagation is that of Raleigh surface waves)

where

E= modulus = 117 GPa =117 *10^9  kg/(m s^2)
rho = density = 8940 kg/m^3
nu = Poisson's ratio =  0.3

vL = 3792 m/s

Length = 0.25 m (latest estimate for the truncated cone's length from aero)

time = 0.25 m / 3792 m/s = 65.9 microseconds

Length = 0.28 m (latest estimate for the truncated cone's Big Diameter from aero)

timeL = 0.28 m / 3792 m/s = 73.8 microseconds

Length = 0.15 m (latest estimate for the truncated cone's Small Diameter from aero)

time = 0.15 m / 3792 m/s = 39.6 microseconds




Velocity of propagation of Raleigh surface (nu=0.3) = vR = 0.93 [E/(rho*2*(1+0.3)) ]

vR = 2087 m/s

Length = 0.25 m (latest estimate for the truncated cone's length from aero)

time = 0.25 m / 2087 m/s = 120 microseconds

Length = 0.28 m (latest estimate for the truncated cone's Big Diameter from aero)

timeL = 0.28 m / 2087 m/s = 134 microseconds

Length = 0.15 m (latest estimate for the truncated cone's Small Diameter from aero)

time = 0.15 m / 2087 m/s = 71.9 microseconds

« Last Edit: 11/01/2014 08:55 PM by Rodal »

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Re: EM Drive Developments
« Reply #2853 on: 11/01/2014 09:22 PM »
The coupling coefficient is non-trivial.  But calculating the Fourier non-dimensional time is trivial, so let's calculate the time for which the Fourier non-dimensional = 1, which is simply ((thickness)^2)/thermalDiffusivity


thermalDiffusivity = 1.11*10^(-4) m/s

so for thickness of copper = 1/8 in = 0.00318 m
hence time = 0.0908 s

so for thickness of copper = 1/16 in = 0.00159 m
hence time = 0.0227 s

so for thickness of copper = 0.022 in = 0.000559 m
hence time = 0.0028 s

So, the initial thermal effect on the copper thickness is clearly impulsive, from the point of view of the much slower response of the inverted torsional pendulum (with period ~ 4.5 s)

Great!  Look at the drumhead expansion of the big end .002" copper FRP w/ resistve heating from the Cu loss!

http://en.wikipedia.org/wiki/FR-4

Did the NASA researchers place that polymer composite on the Big Diameter end on purpose to insulate that end and use the copper/PCBoard to create a bimaterial end to maximize thermal waves ?



Funny they would not comment about its effect on the experiment.

Maybe they didn't think about it 'cause they were spending too much time thinking of the quantum vacuum, General Relativity, and Mach Effects in comparison with classical effects...

One good thing about Shawer's experiments: he does not seem to have placed insulation on the outside of the big end in his experiments, but his experiments do not show a response first characterized by an impulse, on the contrary, he shows a gradual linear rise

« Last Edit: 11/02/2014 12:20 AM by Rodal »

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Re: EM Drive Developments
« Reply #2854 on: 11/01/2014 11:35 PM »
A [Date Acquired: Oct 30, 2014] paper co-authored by Dr. White presented at the Institution of Electrical and Electronic Engineers: http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20140013174.pdf where he discusses short trips to the Jovian and Saturnian moons and "uncovers an energy paradox" (see Appendix A)  ;).

Quote from: White et al
It is not the intent here to detail the theory or engineering of quantum vacuum plasma thrusters (Q-Thrusters). Rather, an overview of the foundational physics and laboratory findings are given.
Q-Thrusters attempt to use the properties of the “quantum vacuum” to propel a spacecraft. Quantum Electrodynamics (QED) predicts that the quantum vacuum (the lowest state of the electromagnetic field) is not empty, but rather a sea of virtual particles and photons that pop into and out of existence stemming from the Heisenberg uncertainty principle.
A number of approaches to utilize this quantum vacuum to transfer momentum from a spacecraft to the vacuum have been synopsized in [1].
A Q-Thruster uses the same principles as conventional plasma thrusters, namely magnetohydrodynamics, where plasma is exposed to crossed electric and magnetic fields which induce a drift of the entire plasma in a direction orthogonal to the applied fields. The difference arises in that a Q-Thruster uses quantum vacuum fluctuations as the “propellant” source, eliminating the need for conventional on-board propellant. A discussion of spacecraft “conservation of energy” is given in Appendix A. Recent laboratory test results [2] indicate the expected thrust-to-power ratio for flight applications could be in the 0.4 – 4.0 N/kWe range, which is one to two orders of magnitude greater than current operational electric thrusters. This combination of characteristics – relatively high specific thrust combined with essentially zero on-board propellant requirement - suggest space mission performance levels significantly exceeding current capabilities.
« Last Edit: 11/01/2014 11:50 PM by Rodal »

Offline RonM

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Re: EM Drive Developments
« Reply #2855 on: 11/01/2014 11:48 PM »
Did the NASA researchers place that polymer composite on the Big Diameter end on purpose to insulate that end and use the copper/PCBoard to create a bimaterial end to maximize thermal waves ?



Funny they would not comment about its effect on the experiment.

Maybe they didn't think about it 'cause they were spending too much time thinking of the quantum vacuum, General Relativity, and Mach Effects in comparison with classical effects... Too much time thinking about the speed of light and not enough thinking about the speed of sound

Didn't they do the same thing on the small diameter end? It would have the same effect, but at a different frequency. How would the two ends interact? This could get complicated.

Online Rodal

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Re: EM Drive Developments
« Reply #2856 on: 11/02/2014 12:26 AM »
Did the NASA researchers place that polymer composite on the Big Diameter end on purpose to insulate that end and use the copper/PCBoard to create a bimaterial end to maximize thermal waves ?



Funny they would not comment about its effect on the experiment.

Maybe they didn't think about it 'cause they were spending too much time thinking of the quantum vacuum, General Relativity, and Mach Effects in comparison with classical effects... Too much time thinking about the speed of light and not enough thinking about the speed of sound

Didn't they do the same thing on the small diameter end? It would have the same effect, but at a different frequency. How would the two ends interact? This could get complicated.

The whole truncated cone EM Drive was cantilevered from the Big End, by two bolts holding the bottom of the FRP PCBoard at the Big End.    Thermoelastic waves at the Big End get transmitted from the Big End to the supports to the beam whose tiny displacements are being measured.
« Last Edit: 11/02/2014 12:52 AM by Rodal »

Offline aero

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Re: EM Drive Developments
« Reply #2857 on: 11/02/2014 01:34 AM »
This is a little better picture showing the mounting. Looks like the cavity is freely resting on the beam. If it is not securely attached at that point, it might transmit vibration even better than through the cantilever.
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Online Rodal

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Re: EM Drive Developments
« Reply #2858 on: 11/02/2014 01:45 AM »
This is a little better picture showing the mounting. Looks like the cavity is freely resting on the beam. If it is not securely attached at that point, it might transmit vibration even better than through the cantilever.
Yes, it is resting at the center of the beam so it only transmits waves with amplitude down at that location.  Calling that beam longitudinal axis x, that vertically down z motion will impart a rotation around the horizontal y axis perpendicular to the x axis.  The torsional inverted pendulum only has rotational degrees of freedom: rotationally around the vertical z axis (torsion) and rotationally around the x and y axes (swinging of the inverted cantilevered beam).

The bolted FRP at the big end transmits force in the y direction that impart a rotation around the vertical z axis, in the direction being measured by their displacement sensor.
« Last Edit: 11/02/2014 02:08 AM by Rodal »

Offline RonM

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Re: EM Drive Developments
« Reply #2859 on: 11/02/2014 01:47 AM »
Wouldn't thermoelastic waves from the small end also cause vibrations that would propagate throughout the device? The copper cone is not going to isolate the two ends. The interaction of vibrations from both ends should produce an interesting pattern.

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