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Registered Member #8120
Joined: Thu Nov 15 2012, 06:06PM
Location: Moscow, Russia
Posts: 94
Not exactly works, at least not the way it's creator thought it should. But they seem to detect an yet-unexplained thrust effect.
Articles:
From discussion here:
wrote ... I was actually at these presentations. There are two competing theories as to how it works. Fetta believes that it works based on asymetry in the design, while White believes it works on pushing against the quantum vacuum. They did 3 cases. An asymetric, a symetric, and a null test. The Asymetric produced thrust at the same rate in all tests, the symmetric produced varying levels of thrust depending on its orientation, and the null test produced no net thrust above background levels.
wrote ... They actually used a few shapes. The asymmetric test was a very flat cyllindrical chamber, about 10 cm high by maybe 30 cm in diameter. One face had short slots (about 4 x 1 cm) carved into it. The symmetric test article was the same as the first, except without the slots. The null case was just a circuit to dissipate the current induced by the rf waves. They also did a test on a generally bell shaped container. I didn't get to see that one in person but based on the pictures I would say its diameter at the top was around 10 cm and at the bottom was around 30 cm. It also produced net thrust but with lower efficiency than the regular cyllinder. Dr. White said that the bell shaped device incorporated findings from the chinese test, so I assume that one had a similar shape.
wrote ... I'm using the term null test differently than the paper. When I say null test, I mean the RF load that was supposed to not do anything to prove that the testing apparatus was not the cause of the anomalous readings.
The paper refers to the symmetric test aparatus as the null test, because it was meant to test a prediction of Fetta's theory on how the device produces thrust (that the force is produced by an imbalance of the lorentz force caused by the asymmetric chamber). This test seems to indicate that Fetta's theory is incorrect (or at the very least innacurate). Dr. White's theory on how thrust is produced however predicted that both test articles should produce thrust, which they did.
I'm not saying that the abstract is wrong, I'm saying it is incomplete and that quote, taken out of context, implies the opposite of what actually happened.
Now the debate on this subject is not over. Fetta sticks to his theory, and is planning on publishing a paper in the next few months (probably around october) on the subject. I do not speak to the validity of either side's claim, I'm merely stating that the issue is different from the one /u/IsTom thinks it is.
No matter who is right it seems propulsion without a conventional propellant is possible. I find this amazing. Someone will probably get a Nobel for this.
Registered Member #8120
Joined: Thu Nov 15 2012, 06:06PM
Location: Moscow, Russia
Posts: 94
Daedronus wrote ... No matter who is right it seems propulsion without a conventional propellant is possible. I find this amazing.
Not exactly. So far it looks more like the recent "neutrinos are faster than light" case - they still haven't ruled out all possible parasitic effects. The thrust produced is quite tiny, well below many possible nose sources. I.e. the test was performed at atmospheric pressure, not in vacuum.
In short, much more research and testing is needed.
Registered Member #2431
Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639
at the "single micro-newton" scale, how can they be sure that E or M fields arn't sneaking in? a little reflection, conduction or stray induction of a radio wave could explain it.
Registered Member #30
Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706
A very valid question. I believe they used a torsion balance which would allow physical movement of the balance to be observed through a microscope, rather than an electronic readout that might be affected by EMI.
Registered Member #72
Joined: Thu Feb 09 2006, 08:29AM
Location: UK St. Albans
Posts: 1659
While I suspect it doesn't work, and it probably sounds like I'm arguing against it, I'm mainly pointing out the loopholes they could close to help to convince non-believers.
An optically observed torsion balance should be capable of reading without EM induced errors, but, how do you get the kW and the water cooling onto the balance without causing uNewtons of effect through stiffness of cables, pipes etc? If you blow air instead of water, it's not much better. If you beam in kW by laser or waveguide horns rather than cables, there are still relatively huge problems to balance.
It would be interesting to see thrust versus predicted plotted for several different input power levels. Proportionality is always a lot more convincing than a non-zero effect.
I like the quantum vacuum thruster concept. The trick here seems to be to coax mass out of the vacuum by 'realising' some of the virtual particles that are seething about all the time. Then, once you have them, throwing them out of the back with MHD. It's a different impossible thing to believe before breakfast. If I understand Hawking correctly, you can realise one of a virtual particle pair at the edge of a black hole. I wonder how the microwaves are supposed to wrench them apart?
I'm also amused at the proposed source of the name 'Cannae drive'. Probably not the geographical place, but a reference to Scotty's "ye cannae change the laws of physics, cap'n".
What is also interesting is that the various drives getting in on the same 'throw a few kW of microwaves into a cavity' bandwagon have different thrust ratios over orders of magnitude.
Registered Member #2431
Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639
Dr. Slack wrote ...
An optically observed torsion balance should be capable of reading without EM induced errors, but, how do you get the kW and the water cooling onto the balance without causing uNewtons of effect through stiffness of cables, pipes etc? If you blow air instead of water, it's not much better. If you beam in kW by laser or waveguide horns rather than cables, there are still relatively huge problems to balance.
It would be interesting to see thrust versus predicted plotted for several different input power levels. proportionality is always a lot more convincing than a non-zero effect.
Thats it, im calling shananigans !!! your stealing my brain waves ! I will find more tin foil Dr. Slack. this is exactly the point i was trying to make in my above comment. theres just so many ways for a tiny but bogus force to appear.
its possible, but id want others to reproduce it, perhaps on both sides of the Atlantic, with different laboratory setups.
I think it is bogus. Virtual particles arise from the quantum mechanical uncertainty relation between time and energy. For very short times there is an energy uncertainty, which leads to the appearance of short lived virtual particles. For a sustained thrust, you need particles which can take momentum on macroscopic time scales, i.e. real particles. These can be e.g. photons. Drives based on photon emission are possible but grossly inefficient.
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emDrive &NASA
I believe they used a torsion balance which would allow physical movement of the balance to be observed through a microscope, rather than an electronic readout that might be affected by EMI.
