EM Drive

Point out news stories, on the net or in mainstream media, related to polywell fusion.

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Axil
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Re: EM Drive

Postby Axil » Tue Apr 28, 2015 6:13 pm

Giorgio, I may be wrong so let's forget it.

Giorgio
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Re: EM Drive

Postby Giorgio » Tue Apr 28, 2015 6:14 pm

Axil wrote:
Giorgio wrote:
Axil wrote: By the way, if you shine a laser down a line of negative vacuum energy, you might get faster than light results.

.......... I mean...... really.....

Here is a paper that explains how negative vacuum energy results in faster than light speeds.

http://arxiv.org/pdf/gr-qc/9805003v2.pdf


Actually no.
This papers just prove that if the metric of space-time can be manipulated to create an arbitrary state of matter like the one in the examples of Alcubierre (which requires negative energy densities), than this can happen ONLY through the weak energy condition (WEC) violation.
Vacuum energy is not mentioned anywhere in this paper.

From the paper itself:
"The present theorem rules out the existence, rather than construction, of superluminal travel, unless there is weak energy condition violation. "
A society of dogmas is a dead society.

Giorgio
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Re: EM Drive

Postby Giorgio » Tue Apr 28, 2015 6:15 pm

Axil wrote:Giorgio, I may be wrong so let's forget it.

No problem.
A society of dogmas is a dead society.

GIThruster
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Re: EM Drive

Postby GIThruster » Tue Apr 28, 2015 10:04 pm

Giorgio wrote:I am asking myself the opposite question. Why it works with the dielectric.
A PE/PP or PTFE immersed in an RF medium might become the fuel that generates the thrust.

As per the M-E explanation, it is basically that they would have had to provide the necessary conditions for a Mach-Effect or mass fluctuation as per Woodward's equations. These are basically that they both alter the internal energy of the dielectric while simultaneously accelerating it. Changing the internal energy is trivial in this environment. Accelerating the bulk mass is the more difficult. If you for example stipulate electrostriction is the accelerating mechanic, you want to note that electrostriction always happens at the 2w. This creates a problem for the M-E explanation. If however you had sufficient 1w acceleration, the 2w electrostriction would generate thrust.

I think the obvious test would be to look for either a 1/2 w signal not noted, or a 2w signal not noted, and the thrust would then be much easier to explain.

Woodward's theory can be found here:

http://www.amazon.com/Making-Starships- ... 1461456223

Long story short though, if indeed we had both the necessary conditions to generate a Mach Effect, and the conditions to rectify the delta mass into thrust, we would have an answer here. Were for example the test dielectric both piezoactive (1w mechanical action) and electrostrictive (2w mechanical action) thrust here would be very easy to explain with M-E theory. However, I was under the impression they had used a polymer dielectric with no piezo response. Anyone know if this is true?
"Courage is not just a virtue, but the form of every virtue at the testing point." C. S. Lewis

Giorgio
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Re: EM Drive

Postby Giorgio » Wed Apr 29, 2015 4:52 am

GIThruster wrote: Were for example the test dielectric both piezoactive (1w mechanical action) and electrostrictive (2w mechanical action) thrust here would be very easy to explain with M-E theory. However, I was under the impression they had used a polymer dielectric with no piezo response. Anyone know if this is true?

Can't remember that right now, but my doubt is that any dielectric immersed in a RF field can undergo micro combustion spots (due to localized impurities) that will generate a thrust.
As for now I would be more interested in a good scan of the surface of the dielectric before and after the experiments.
A society of dogmas is a dead society.

ScottL
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Re: EM Drive

Postby ScottL » Wed Apr 29, 2015 11:33 pm

Dr. Rodal and contributors have released an article on the EM Drive: http://www.nasaspaceflight.com/2015/04/evaluating-nasas-futuristic-em-drive/

Giorgio
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Re: EM Drive

Postby Giorgio » Thu Apr 30, 2015 6:30 am

Quite a nice sum up of the story so far.
Thanks for posting it.
A society of dogmas is a dead society.

GIThruster
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Re: EM Drive

Postby GIThruster » Thu Apr 30, 2015 6:19 pm

They were very nice and more than fair to Eagle. I would just point out a few corrections/objections I have.

The magnetrons used in the past are not like that in a microwave oven. Shawyer and the Chinese both used Continuous Wave Magnetrons. The $25 vacuum tubes in a microwave over are not CW tubes and would burn out immediately if one tried to use them this way.

So far as I'm aware, Sonny did not predict 50mN thrusts as the piece states. He did not make any predictions despite he was asked to. He merely fit his model to the data after it came out, again. It is a complete falsehood to say he predicted the results when he was repeatedly asked and refused to answer. This is his pattern. I would just remind you all that Paul has been posting at NSF and making statements through NBF since well before there was an Eagleworks, and there have never been any magnitude predictions come from that lab. It is completely false to claim to make predictions when they come after the data, and Sonny has had this explained to him on numerous occasions.

I am very surprised that Rodal is writing Eagle have ruled out atmospheric heating as a spurious source. His analysis was that they should not have so ruled. I have to wonder why this change.

I still say this is fundraising. Sonny is running scared because they're closing him down. To keep his funding he was supposed to hit 100mN and he has not done this. IIRC, that figure was stipulated before he had funding because that is what they need for the balances at places like Glenn to work, so if Sonny had made any private predictions, they would certainly have been for more than 100nM.

Looks like more of the same to me. I am shocked however that Rodal has his name on a piece that says Eagle has ruled out thermal from lack of vacuum and yet has no comment about that himself. As I said, more than fair. That was very gracious of him.
"Courage is not just a virtue, but the form of every virtue at the testing point." C. S. Lewis

choff
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Re: EM Drive

Postby choff » Thu Apr 30, 2015 7:36 pm

A new article on ME in the Independent.

http://www.independent.co.uk/life-style ... 15544.html
CHoff

ScottL
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Re: EM Drive

Postby ScottL » Thu Apr 30, 2015 9:52 pm

I believe Dr. Rodal changed his mind over the past few months after pouring through the data provided by Paul. If I've read the thread properly, I think he's still skeptical of the theory, but has come around to the experimental results as of late. I think the fact that they just ran it in vacuum and saw the same thrust signature was the final push he needed to side on the evidence. I, like you, still find the theory to be complete bunk, but Paul seems to be making valid headway in quieting skeptics with experimental results.

JoeP
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Re: EM Drive

Postby JoeP » Fri May 01, 2015 1:33 am

ScottL wrote:I believe Dr. Rodal changed his mind over the past few months after pouring through the data provided by Paul. If I've read the thread properly, I think he's still skeptical of the theory, but has come around to the experimental results as of late. I think the fact that they just ran it in vacuum and saw the same thrust signature was the final push he needed to side on the evidence. I, like you, still find the theory to be complete bunk, but Paul seems to be making valid headway in quieting skeptics with experimental results.
There was link now on the Drudge report I saw earlier tonight...although the article gets a lot of things wrong, it seems that this is getting some public attention.

Edit: eh, it was the same article that Choff linked. But Drudge is more exposure. Too bad that flawed article is what is making the rounds and not Rodal's.

Tom Ligon
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Re: EM Drive

Postby Tom Ligon » Fri May 01, 2015 1:46 am

GIThruster wrote:The magnetrons used in the past are not like that in a microwave oven. Shawyer and the Chinese both used Continuous Wave Magnetrons. The $25 vacuum tubes in a microwave over are not CW tubes and would burn out immediately if one tried to use them this way.



Ah, but microwave oven magnetrons WILL run CW. We did it routinely at EMC2. True enough, most microwave ovens run an incomplete voltage doubler that pulses half waves of 60 Hz high voltage to drive these magnetrons, but we'd hook them up to a regulated HV DC supply and they're run happily. And they are robust ... very hard to burn out. I don't recall burning one out, although the first one we used eventually got kind of tired (RBW had used that oven in his kitchen for years before we cannibalized it for the lab).

The real problem with microwave oven magnetrons is that they chatter all over the spectrum. I put a spectrum analyzer on them and they're just ratty microwave sources. If you are investigating a phenomenon that requires matching frequency to a tuned cavity, you need a microwave source that stays on frequency.

tokamac
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Re: EM Drive

Postby tokamac » Fri May 01, 2015 1:21 pm

Tom Ligon wrote:The real problem with microwave oven magnetrons is that they chatter all over the spectrum. I put a spectrum analyzer on them and they're just ratty microwave sources. If you are investigating a phenomenon that requires matching frequency to a tuned cavity, you need a microwave source that stays on frequency.

I thought the same at the beginning. But actually, it has been shown magnetrons would be BETTER for EmDrive than a clean pure sine-wave generator, precisely because magnetrons are noisy. They produce a modulated FM bandwidth of at least +/-30 MHz that is also concurrently amplitude modulated (AM) with thermal electron noise.

That could be better for several reasons, mainly because the cavity is heated and quickly becomes hard to keep in resonance if the operating frequency bandwidth is too short. Quoting Paul March:
Why does NASA have difficulties running the EM Drive in the more efficient mode (the Transverse Electric mode) ? Because the most efficient mode results in greater shifting of its natural frequency with time. Hence I agree with Mulletron that instead of having the power concentrated at a frequency, for a problem where we know that the natural frequency of the EM Drive changes with time in a difficult to calculate and predict (with enough precision) manner, the best solution is to have the power distributed over a wider spectrum of frequencies, as done by Prof. Juan Yang in China.

GIThruster
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Re: EM Drive

Postby GIThruster » Fri May 01, 2015 2:53 pm

I couldn't help but notice in Rodal's piece that they quote the eagle claims that this modulation generates more thrust, and that their recent simulation explains why, as well as why the dielectric produces thrust, but neither of those explanations have been published in any forum so far as I'm aware.

Is there something at NSF that explains why this modulation and the dielectric should produce thrust?
"Courage is not just a virtue, but the form of every virtue at the testing point." C. S. Lewis

tokamac
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Re: EM Drive

Postby tokamac » Fri May 01, 2015 3:37 pm

GIThruster wrote:I couldn't help but notice in Rodal's piece that they quote the eagle claims that this modulation generates more thrust, and that their recent simulation explains why, as well as why the dielectric produces thrust, but neither of those explanations have been published in any forum so far as I'm aware.

Is there something at NSF that explains why this modulation and the dielectric should produce thrust?


This started with this post on NSF by Paul March, April 5, 2015:
Dr. Rodal:

I think that the reason why the Neoprean rubber didn't generate any detectable thrust with the ~30W of available power was that it's carbon loaded which increases its RF loss tangent from that of HDPE or PTFE (~0.0004) up to 0.02 which really loads down the net E-field generated in the cavity for a given input power. And since we think that the thrust effect we are observing is proportional to E-field squared (E^2) that could make a huge difference in performance.

Now please note that I concur with your analysis on the E&M Poynting vector time averaging to zero in the frustums. For example when the Cannae pillbox cavity's input RF power feed is well Z-matched with a VSWR= ~1.00, the RF Poynting power flow into the cavity is always towards the large OD pancake section of the cavity. If one envisions the quantum vacuum (Q-V) as a semi-virtual electrical plasma as Dr. White does, that would imply that the Poynting power flow vector would entrain the Q-V plasma and send it on its way toward the pillbox end of the cavity and then out of the cavity, the back-reaction on the cavity should be in the opposite direction towards the RF feed end of the Cannae test article, but the observed thrust vector is opposite to that surmise, i.e. toward the shorter RF sense antenna end of the cavity per the attached slide.

Now Per the newly authored Q-V plasma simulation code that Dr. White just finished, the equal bidirectional Q-V plasma flow for the Cannae cavity comes from the high-Q pancake section with a Q of ~9,000 for the un-slotted version of the cavity. However due to the high E-field region created n the throat of the RF feed, this cylindrically shaped high E-field volume acts as an obstruction to the Q-V plasma flow. This E-field obstruction created in the PTFE cylinder then accelerates the Q-V plasma around it in a Bernoulli like effect that accelerates the Q-V plasma flow coming from the main pillbox cavity. This unbalanced and accelerated Q-V plasma flow that goes away from the large pill box cavity in the direction of the RF input section is what generates the NET thrust in our model.

Next, using this new Q-V plasma simulation tool that utilizes the instantaneous E&M fields from COMSOL for one complete RF cycle in 5 degree increments as its input file, we are now seeing why we need the PTFE or HDPE dielectrics in the frustum while using near pure sine wave power levels below ~100W in the ~2.0 GHz frequency range to generate detectable thrust, and why Shawyer and the Chinese didn't while pumping 80W to 2,500W using magnetron RF sources. We think the reasons are two fold.

The first is that Shawyer and the Chinese both used magnetron RF sources for their experiments. An RF source that generates large AM, FM and PM modulation of the carrier wave with typical FM modulation bandwidth on the order of at least +/-20 MHz. (These time rate to change of energy modulations increase the Q-V density in our model.)

The second reason we found running these 3D Q-V plasma simulations for the EMPTY copper frustum, was that increasing the input power tends to focus the Q-V plasma flow from near omnidirectional from the frustum at low powers, to a much more jet like beam at higher powers measured in kW to tens of kW-rf. In fact the simulation for the 100W run predicted only ~50uN for our pure RF system with dielectric, while the 10kW run predicted a thrust level of ~6.0 Newton without a dielectric in the cavity. And at 100kW-rf it was now up to ~1300 Newton, but the input power to thrust production nonlinearity was starting to taper off around 50kW. Of course these Q-V plasma thrust predictions are based on the Q-V not being immutable and non-degradable, a feature we admit is not widely accepted by the mainstream physics community, at least at the moment. :)


Lastly, due to the above non-linear thrust scaling with input power predictions, we have started the build up of a 100W-to-1,200W waveguide magnetron RF power system that will drive one of our aluminum RF frustum cavities. Initially the test rig will follow Shawyer's first generation test rig that used a tetter-totter balance system in air only to see if we can generate similar thrust levels that Shawyer reported using a hermetic sealed box, which were in the ~16 to 300 milli-Newton range dependent on the Q-Factor of the frustum.

BTW, the reason we included the "what-if" Eagleworks can make this thing work solar system trajectory section on our 2014 JPC paper was that we have to continually tell management the value proposition for why they should fund our research, much in the same way we have to convince Chris Bergin here at NSF we really will be talking about space applications for these Q-Thruster like devices, once we get our hands around the physics they are using. However when we do, the solar system and beyond will be ours for the picking...


But Paul didn't theoretically explain how the "almost omnidirectional flow of QV particles at low power" would be enhanced and controlled by a dielectric to produce some thrust, nor why that almost omnidirectional flow of QV particles becomes a "directional spike" at higher power in a non-linear way, with no need for a dielectric to produce considerable more thrust.

Good question, Ron. I asked Paul March and Dr. Rodal there. Dr. Rodal answered:
As discussed in the article, these are reported results from the computer model of Dr. White. Whenever there is a numerical computer analysis result reported, the validity of the results is entirely dependent on 1) the validity of the physical model underlying the numerical model, 2) the validity of the numerical implementation, 3) the validity of the computer programming ("bugs" and any errors of any kind) and 4) the validity of the input data. Even if the computer simulation is valid (under the previously discussed considerations), the results of a complicated numerical analysis may not be readily understood. For example, entirely valid results from numerical simulations of nonlinear dynamic impact and explosive blasts on aerospace structures are very difficult to understand without careful consideration (ideally, difficult to understand computer predictions should always be backed up by experiments). Examples abound, think for example of how possible impact of foam was mishandled and misunderstood by NASA on a Space Shuttle disaster.

Experimental testing is needed to verify these computer analysis predictions. Reportedly this will occur in June of July of this year.
Last edited by tokamac on Fri May 01, 2015 4:31 pm, edited 1 time in total.


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