EM Drive

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

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birchoff
Posts: 200
Joined: Sun Jul 27, 2014 7:11 pm

Re: EM Drive

Post by birchoff »

Diogenes wrote:
ScottL wrote:Well folks, looks like the "leaked" paper and all the rumors have been sourced to an NSF member that goes by the name "TheTravellerReturns." This particular NSF user has a history of rage-quitting their forum only to come back. Has denied he was the source, although that denial is hard to refute now that Ibtimes has outed him as the original articles source. Has spread untrue/fantastical rumors about the testing of the EmDrive on various rockets. I find this type of behavior appalling. This does not bode well for the EmDrive community.


There are some people who feel that what they want to believe is so compelling, they must force it to become the truth by their own actions.


Usually these sorts of people are in politics, but there has been recent upsurge in this reality warping behavior in many disciplines, even science. Global Warming comes to mind.


I would like for propellent-less drive to be a real thing, but i'm not going to lie to myself or others in a futile effort to make it happen.
While I agree with the characterization. This only Affects the EmDrive as far as finding trust worthy people to accept results from. I have been following the NSF Forum for long enough that I doubt there is a grain of salt big enough to take with anything Traveller says. Right now he would have to actually deliver on his proclamation of building a EmDrive rated in the N's of thrust range before I would do anything other than gloss over what he says on that forum. That said, any work from EW leaked or officially released is still good work. I think at the moment the only question is if the leak is the previously denied draft or the final version. Either way it is obvious they did alot of work to remove error sources which seems to have not only disambiguated force from error but also increased measured thrust. That gets a huge plus in my book. If the leak is same as what AIAA officially releases then I think the only thing missing is the raw data they collected as they reference the raw data many times in the leaked paper. If it is an earlier draft that was rejected then my hopes are even higher that there are more interesting bits in the official release along side some raw data.

Either way untrusted sources aside, the Emdrive looks much more real and less smoke and mirrors.

ScottL
Posts: 1122
Joined: Thu Jun 02, 2011 11:26 pm

Re: EM Drive

Post by ScottL »

I didn't find the leaked paper very convincing. While I'm not a physicist, I did note some issues that my CSEE degree at least recognizes.

Carl White
Posts: 321
Joined: Mon Aug 24, 2009 10:44 pm

Re: EM Drive

Post by Carl White »

Measurement of Impulsive Thrust from a Closed Radio-Frequency Cavity in Vacuum
Harold White, Paul March, James Lawrence, Jerry Vera, Andre Sylvester, David Brady, Paul Bailey
NASA Johnson Space Center, Houston, Texas 77058

http://arc.aiaa.org/doi/10.2514/1.B36120

hanelyp
Posts: 2255
Joined: Fri Oct 26, 2007 8:50 pm

Re: EM Drive

Post by hanelyp »

Carl White wrote:Measurement of Impulsive Thrust from a Closed Radio-Frequency Cavity in Vacuum
Harold White, Paul March, James Lawrence, Jerry Vera, Andre Sylvester, David Brady, Paul Bailey
NASA Johnson Space Center, Houston, Texas 77058

http://arc.aiaa.org/doi/10.2514/1.B36120
Once again I'm not seeing a sufficient description of the RF feed setup to evaluate feed line photon pressure as a measurement artifact.
The daylight is uncomfortably bright for eyes so long in the dark.

Carl White
Posts: 321
Joined: Mon Aug 24, 2009 10:44 pm

Re: EM Drive

Post by Carl White »

hanelyp wrote:
Carl White wrote:Measurement of Impulsive Thrust from a Closed Radio-Frequency Cavity in Vacuum
Harold White, Paul March, James Lawrence, Jerry Vera, Andre Sylvester, David Brady, Paul Bailey
NASA Johnson Space Center, Houston, Texas 77058

http://arc.aiaa.org/doi/10.2514/1.B36120
Once again I'm not seeing a sufficient description of the RF feed setup to evaluate feed line photon pressure as a measurement artifact.
What if you assume maximum possible photon pressure (i.e. all power is converted at 100% efficiency into a uni-directional photon rocket). Would the thrust produced be sufficient to account for the readings?

krenshala
Posts: 914
Joined: Wed Jul 16, 2008 4:20 pm
Location: Austin, TX, NorAm, Sol III

Re: EM Drive

Post by krenshala »

I haven't read past sections II A and B yet, but it sounds an awful lot like a variant on an MET so far (in as much as I think I understand how the MET is working, that is :D ).

happyjack27
Posts: 1435
Joined: Wed Jul 14, 2010 5:27 pm

Re: EM Drive

Post by happyjack27 »

The Peer-Reviewed EmDrive Paper Is Officially Out

http://www.iflscience.com/space/the-pee ... ially-out/

hanelyp
Posts: 2255
Joined: Fri Oct 26, 2007 8:50 pm

Re: EM Drive

Post by hanelyp »

Carl White wrote:
hanelyp wrote:
Carl White wrote:Measurement of Impulsive Thrust from a Closed Radio-Frequency Cavity in Vacuum
Harold White, Paul March, James Lawrence, Jerry Vera, Andre Sylvester, David Brady, Paul Bailey
NASA Johnson Space Center, Houston, Texas 77058

http://arc.aiaa.org/doi/10.2514/1.B36120
Once again I'm not seeing a sufficient description of the RF feed setup to evaluate feed line photon pressure as a measurement artifact.
What if you assume maximum possible photon pressure (i.e. all power is converted at 100% efficiency into a uni-directional photon rocket). Would the thrust produced be sufficient to account for the readings?
If you have a standing wave from feeding a high Q resonator you can get many times more "thrust" than a photon rocket. The simple way to avoid this artifact is to put the entire RF system on the force balance, which I'm not seeing described.

Another potential artifact, depending on setup, is torque generated by current through twisted pair wires. This can again be accounted for by experimental setup details I'm not seeing described.
The daylight is uncomfortably bright for eyes so long in the dark.

RERT
Posts: 121
Joined: Mon Jun 02, 2014 9:10 pm

Re: EM Drive

Post by RERT »

They say the RF amp was on the Torsion pendulum arm.

Tom Ligon
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Location: Northern Virginia
Contact:

Re: EM Drive

Post by Tom Ligon »

Aw, come off it guys.

I did a BOE calculation on this last night, thinking that 1.2 mN is less thrust than a good fart, but I was in error. It is actually several times as much thrust as a good fart, plus it is continuous and not just a fraction of a second.

Still, I produce gas while running considerably less than 1 kW.

The thing is, it does appear to do something, and that's good enough to get others to try to confirm it, taking all the potential objections into account. And it encourages theories to try to figure out how it could happen.

A friend of mine (credibility undetermined) believes there are some twisted around ways of applying Maxwell's equations that should do a lot better. He'll then demonstrate some right hand rule orientations not normally considered, and show that forces can emerge which are not equal and opposite. So maybe this cockeyed cone is just producing some interactions at odd angles that don't show up in a well-designed waveguide, and maybe the shape can be made better.

Let it play out. The apparatus ain't bad for a budget attempt, tho' it could clearly use improvement to overcome the objections.

Or maybe, like the FTL anomoly in a neutrino experiment, they'll find a bad connector in the setup.

RERT
Posts: 121
Joined: Mon Jun 02, 2014 9:10 pm

Re: EM Drive

Post by RERT »

My BOE says 300 micro-Newtons will keep Cannae's 6U cubesat on station at 180km (very low altitude) forever.

1.2mN/Kw would only require a small solar panel to power it.

tokamac
Posts: 55
Joined: Wed Nov 04, 2009 2:50 pm

Re: EM Drive

Post by tokamac »

krenshala wrote:I haven't read past sections II A and B yet, but it sounds an awful lot like a variant on an MET so far (in as much as I think I understand how the MET is working, that is :D ).
Hi,

The EmDrive and the Mach-Effect Thruster operate very differently:
  • The EmDrive is a closed resonant cavity where microwaves are reflected within back and forth between two end plates. According to Shawyer, a thrust arises purportedly because of the asymmetry of the cavity, which is a truncated cone (or frustum).
  • The MET is a stack of piezoelectric discs that vibrate back and forth when an AC voltage is applied on them. According to Woodward, a transient mass fluctuation arises in the accelerated discs as a Mach effect. The system is tuned so the discs can push forward when they are heavier, and backward when they are lighter.
The EmDrive uses electromagnetic waves in the GHz frequency range, whereas the MET is a solid-state device vibrating in much lower frequencies.

Please note that according to Woodward, the EmDrive may be explained with some Mach effect (interaction of the EM waves with the polymer insert or the material of the cavity walls).

krenshala
Posts: 914
Joined: Wed Jul 16, 2008 4:20 pm
Location: Austin, TX, NorAm, Sol III

Re: EM Drive

Post by krenshala »

tokamac wrote:
krenshala wrote:I haven't read past sections II A and B yet, but it sounds an awful lot like a variant on an MET so far (in as much as I think I understand how the MET is working, that is :D ).
Hi,

The EmDrive and the Mach-Effect Thruster operate very differently:
  • The EmDrive is a closed resonant cavity where microwaves are reflected within back and forth between two end plates. According to Shawyer, a thrust arises purportedly because of the asymmetry of the cavity, which is a truncated cone (or frustum).
  • The MET is a stack of piezoelectric discs that vibrate back and forth when an AC voltage is applied on them. According to Woodward, a transient mass fluctuation arises in the accelerated discs as a Mach effect. The system is tuned so the discs can push forward when they are heavier, and backward when they are lighter.
The EmDrive uses electromagnetic waves in the GHz frequency range, whereas the MET is a solid-state device vibrating in much lower frequencies.

Please note that according to Woodward, the EmDrive may be explained with some Mach effect (interaction of the EM waves with the polymer insert or the material of the cavity walls).
I am aware of the differences. But the description of the EM drive operation (resonance modes) in the paper seems very similiar to the desired resonance modes Woodward is attempting to improve on for the MET. At least, to me they seem similar. I'm far from a qualified expert on either, however, so apply salt as necessary. :D

williatw
Posts: 1870
Joined: Mon Oct 12, 2009 7:15 pm
Location: Ohio

Re: EM Drive

Post by williatw »

Could Dark Matter Be Powering The EMdrive?


Image
The experimental setup of the EMdrive. Image credit: H. White et al., “Measurement of Impulsive Thrust from a Closed Radio-Frequency Cavity in Vacuum”, AIAA 2016.

But if photons moving in a particular direction — towards the ‘back’ of the cavity, for example — are likely to strike a dark matter particle, three things ensue:
1.The photon changes momentum, and moves “less backwards” and “more forwards” than before it struck the dark matter particle.
2.The photon strikes the inside wall of the cavity, reflecting off of it and imparting its momentum in the forward direction to the cavity itself.
3.The struck dark matter particle gains momentum as well in the opposite direction: backwards.

Momentum is conserved because the dark matter carries it away, equal and opposite in magnitude to what the cavity absorbs.
For every action, there’s an equal and opposite reaction. This formulation of Newton’s third law has two very important modern consequences: one, that there’s a physical quantity that’s always conserved in the Universe (momentum), and two, that the laws of physics are the same irrespective of your position in space. This has a huge slew of implications, including that if you want to power a device to change its motion, you need to push against something. This could be exhaust from a rocket, tires pushing against a road, train wheels on a rail-line or even photons reflected off a sail. The one thing that’s forbidden is a reactionless drive: an action without a reaction. That’s exactly what the EMdrive — the ‘impossible’ space engine just verified by a NASA test — claims to be. If it truly works as advertised, it violates the laws of physics. But there’s a possible loophole: perhaps there is a reaction, and we just don’t detect it. Perhaps the reaction occurs, but it’s occurring due to dark matter.
Image
Image credit: ESO/L. Calçada, of the illustration of the dark matter halo surrounding the luminous disk of our galaxy.

According to the standard model of cosmology, the majority of the matter in the Universe isn’t in the form of atoms, or of any known particle. Rather, the overwhelming majority of mass — by a 5-to-1 margin — is in the form of dark matter. Dark matter doesn’t collide, annihilate or otherwise interact with either itself or other, normal matter under any known circumstances, but rather interacts only gravitationally. After 13.8 billion years like this, it forms a vast, diffuse cosmic network of gravitational structure, and forms huge spherical haloes more than a million light years in diameter that contain galaxies like our own. This means, all told, that dark matter permeates every square centimeter of our galaxy, including existing — albeit in small densities — inside every object on Earth, including our own bodies.
Image
Photons and axions can couple together under the right conditions, in theory, and may potentially be detectable via a number of methods. Image credit: Thomas Papaevangelou, via his talk, CAST: Recent Results & Future Outlook.
Under the right conditions, however, dark matter can be coaxed to interact with either itself or with normal matter, dependent on its nature. If dark matter is made up of WIMPs (weakly interacting massive particles), then it has an annihilation cross section with itself and a scattering cross section with protons and neutrons that may render it sensitive to detectors. If instead, it’s made up of very light, low-mass particles known as axions, it may couple to photons under the right conditions. One of the experiments designed to search for axions is known as ADMX: the axion dark matter experiment. In 1983, physicist Pierre Sikivie invented the axion haloscope, which takes advantage of the fact that the axion-photon coupling can be amplified, with the right parameters, inside an electromagnetic cavity. Twelve years later, ADMX grew out of that research, and scientists have been searching for the axion ever since using that method.
How would it work? At any point in time, there are dark matter particles passing through all regions of space, undeterred by the presence of matter or other Standard Model particles. Inside the electromagnetic cavity, photons of a particular frequency bounce around in all directions, conserving momentum and generating no thrust. But if photons moving in a particular direction — towards the ‘back’ of the cavity, for example — are likely to strike a dark matter particle, three things ensue:

1.The photon changes momentum, and moves “less backwards” and “more forwards” than before it struck the dark matter particle.
2.The photon strikes the inside wall of the cavity, reflecting off of it and imparting its momentum in the forward direction to the cavity itself.
3.The struck dark matter particle gains momentum as well in the opposite direction: backwards.

Momentum is conserved because the dark matter carries it away, equal and opposite in magnitude to what the cavity absorbs.




http://www.forbes.com/sites/startswitha ... 748041e539

hanelyp
Posts: 2255
Joined: Fri Oct 26, 2007 8:50 pm

Re: EM Drive

Post by hanelyp »

If the EM drive works by pushing on ambient dark matter that addresses the conservation of energy-momentum objection. But it also implies that performance strongly depends on the local dark mater motion frame (unless interaction favors dark matter particles with a favored relative velocity). And since the dark matter density is normally a practical vacuum, it has very little to push against even if all the dark matter in the resonant chamber can be used as reaction mass.

And if photons in a chamber can push on dark matter it raises the question of why this not entirely dark matter doesn't block much starlight.
The daylight is uncomfortably bright for eyes so long in the dark.

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