EM Drive

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

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birchoff
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Re: EM Drive

Postby birchoff » Tue Aug 05, 2014 4:37 am

Aero wrote:I read the abstract linked in the OP on some post either here or on NSF. Is there a complete report on the experiment by White, et.al available somewhere?

And by the way, microwave oven frequency is chosen at the water line, so the microwave energy will excite the water in the food. Is the frequency White is using chosen to for the "virtual particle line?" If not, why not, and if so, how does he know what it is?


According to my understanding of the paper, along with the Shawyer and Yang papers the frequency chosen is the resonance frequency of the microwave cavity being tested.

I will have to go back through papers again to find how each of them determine this, maybe someone else will do that work for me and post it below

GIThruster
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Re: EM Drive

Postby GIThruster » Tue Aug 05, 2014 4:18 pm

The cavity is built to accomodate resonance at the frequency of the wave generator. In order to resonate, the cavity has to have a distance between the plates of a 1/2 wave whole number multiple of the frequency chosen. So at 2.45 Ghz, the wave has a half wavelength of about 6 cm. The cavity has to be built so that the end plates are as precisely as possible, a whole number multiple of 6.xxxx cm.
"Courage is not just a virtue, but the form of every virtue at the testing point." C. S. Lewis

hanelyp
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Re: EM Drive

Postby hanelyp » Tue Aug 05, 2014 4:47 pm

A lot of objections regarding testing of this general class of thrusters are addressed if:
- The RF or high voltage generator is part of the test apparatus,
- The whole test apparatus is enclosed in a Faraday cage,
- And the whole apparatus, including the Faraday cage, is operated in hard vacuum or in a hermetically sealed enclosure on the test balance.

A DC feed is a lot easier to isolate from field influences than an RF transmission line.
The whole closed RF / high voltage system inside a Faraday cage contains field influence to anything not part of the test apparatus.
The hard vacuum or sealed enclosure prevent ion wind from escaping the test system.
The daylight is uncomfortably bright for eyes so long in the dark.

GIThruster
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Re: EM Drive

Postby GIThruster » Tue Aug 05, 2014 5:13 pm

These above are the same scientific controls missing from Shawyer's work. IIRC, they have been addressed to major extent with the work at Eagle. Certainly they test everything in their stainless steel vacuum chamber. One of the objections I heard about the work at Eagle was that they had reported all manner of thrusts until they finally stopped the em coupling between the feeds and the chamber. Then all the thrust went away. This same trouble with vacuum chambers made of stainless has occurred up in Canada in George Hathaway's work, which he carefully documented on the web; as well as other places such as Earthtech, IIRC.

Woodward has avoided the lion's share of these troubles simply by going with an acrylic tank in place of the stainless. While its true he can't pull as hard a vacuum as one can with stainless, it's also true you don't need that to clearly rule out things like ion wind and thermal. You cannot remove all possible ion wind with the E-3T vacuum used in Woodward's setup, but you can show that if you get the same thrust readings at ambient, E-1T, E-2T and E-3T, they you KNOW you don't have ion wind or thermal contributions because these scale with pressure. So you don't really NEED a $250k hard vacuum setup and an additional year to characterize the chamber and qualify it for HV. What you do need, is the proper protocols designed by someone who knows how to do proper science, and that person is not Shawyer.
"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 » Tue Aug 05, 2014 9:17 pm

Another article, this time with the full NASA paper inside (second link, after Wired):


GIThruster
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Re: EM Drive

Postby GIThruster » Tue Aug 05, 2014 11:34 pm

I'll have to find time to read that. It's important to note, that Shawyer's theory (not really that) violates conservation, and Sonny's model violates EEP. Here's what a cal tech physcist thinks of Sonny's hopeless bullshit:

CalTech physicist Sean Carroll, who, earlier this week, equated the notion of "propulsive momentum transfer via the quantum vacuum virtual plasma" to "nonsensical sub-Star-Trek level technobabble," had more to add, telling io9:

The business about "quantum vacuum virtual plasma" (the physics of which they "won't address" in this paper) is complete bullshit. There is a quantum vacuum, but it's nothing like a plasma. [The researchers] hook up a gizmo with all sorts of electromagnetic fields fluctuating around, then claim to measure an extremely tiny thrust (about the weight of a single grain of sand), which occurs even for the test article that wasn't supposed to produce any thrust at all.

Carroll's final point – that the researchers measured thrust not only when the drive was configured to produce it, but also when set up to do nothing at all – may be the most important takeaway of all. It's a point Mika McKinnon expands upon in her explanation below.


http://space.io9.com/a-new-thruster-pus ... rtgonzalez
"Courage is not just a virtue, but the form of every virtue at the testing point." C. S. Lewis

Aero
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Re: EM Drive

Postby Aero » Wed Aug 06, 2014 6:29 am

Carroll's final point – that the researchers measured thrust not only when the drive was configured to produce it, but also when set up to do nothing at all – may be the most important takeaway of all. It's a point Mika McKinnon expands upon in her explanation below.


It's funny that everyone I've read thinks that is important, that it points at an experimental error. Bull.

This is what's important. From what little I understand of it, he's right.

The business about "quantum vacuum virtual plasma" (the physics of which they "won't address" in this paper) is complete bullshit.


It is important to understand that the device in question was the Cannae design, based on their in-house theory, designed and built not by NASA, but by Cannae, LTD (out of Pennsylvania, IIRC.)

Now, if you design one thing to work one way and another thing almost like it to work another way, or not work, using an idea of what makes it work in the first place that is completely wrong - then why is it surprising that you did not get the results you expected? What that proves to me is this:

The business about "quantum vacuum virtual plasma" is complete bullshit.

There is another mechanism in play but the error shown here is an error in theory, his understanding of what makes it work or not work is wrong. But we've known that we don't understand what makes the EM Drive work every since the first information on the EM Drive was published. Just because Cannae still does not understand it DOES NOT make the cause of the measured result an experimental error.

Don't misunderstand me, this lack a theory of operation does not rule out experimental error, but neither does it add one iota of evidence for experimental error.
Aero

GIThruster
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Re: EM Drive

Postby GIThruster » Wed Aug 06, 2014 1:47 pm

Yes well Carroll does separate the two. He was cited and the author said "Carroll's final point. . " and went on to develop a second issue. You're right, the two are no related logically, but the first objection, that QVF physics is bullshit, and the second point, that the experimental setup was obviously wrong since it produced thrust even when it was not supposed to, are each individually significant enough to dispense with the nonsense.

NASA really is discrediting itself here again. This is far worse than the stuff with Eugene Podklatnov back in the 90's.
"Courage is not just a virtue, but the form of every virtue at the testing point." C. S. Lewis

Skipjack
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Re: EM Drive

Postby Skipjack » Wed Aug 06, 2014 2:11 pm

NBF has picked up on the whole thing as well. I am a tiny bit more hopeful after reading the full paper, but not a whole lot. I really wished it was true but it will take more replications for me to believe it is.
http://nextbigfuture.com/2014/08/full-n ... -test.html

GIThruster
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Re: EM Drive

Postby GIThruster » Wed Aug 06, 2014 2:37 pm

tokamac wrote:Another article, this time with the full NASA paper inside (second link, after Wired):



Gets a fail. Obviously written by a non-science person reporting about stuff they haven't fact checked. It's got too many serious errors to be taken as real journalism.
"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 » Wed Aug 06, 2014 2:47 pm

GIThruster wrote:
tokamac wrote:Another article, this time with the full NASA paper inside (second link, after Wired):



Gets a fail. Obviously written by a non-science person reporting about stuff they haven't fact checked. It's got too many serious errors to be taken as real journalism.


I agree. But I was not linking to this article for its (bad) content, but only for the full NASA paper available in it.

Carl White
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Re: EM Drive

Postby Carl White » Thu Aug 07, 2014 6:34 pm

Any chance they already have the materials needed to build one of these on the ISS? And then chuck it out an airlock to test it?

It's the only way people will be definitively convinced (if the thing actually works).

tokamac
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Re: EM Drive

Postby tokamac » Thu Aug 07, 2014 9:13 pm

Carl White wrote:Any chance they already have the materials needed to build one of these on the ISS? And then chuck it out an airlock to test it?

It's the only way people will be definitively convinced (if the thing actually works).

I see various possibilities that would keep ramping interest and development up (assuming this thing really works):

  1. Positive IV&V (Independent Verification & Validation) from respectable labs.
  2. Positive results of a cubesat testing from ISS.
  3. A true working and falsifiable theory, either based on Mach's principle within GRT, Quantum Vacuum Fluctuations, a scalar-tensor theory, a theory involving dark-matter axions… or anything else that doesn't break the laws of physics and accurately predicts some behavior of those devices. More experimental data is needed for the emergence of such theoretical framework.
  4. Increasing specific thrust with respect to power and Q factor in future experiments.
  5. A high power, superconducting, earth-based version of an EmDrive that would float above the ground with no sound. I'd like this one ;)

AcesHigh
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Re: EM Drive

Postby AcesHigh » Thu Aug 07, 2014 11:12 pm

just as someone pointed out at NASA SpaceFlight Forums, we had for years high temperature superconductors without any theory for how they worked. An EM Drive may follow the same pattern. If it WORKS, people will have to accept it and LATER they will have to come with theories.

Tom Ligon
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Re: EM Drive

Postby Tom Ligon » Fri Aug 08, 2014 12:24 am

tokamac wrote:Another article, this time with the full NASA paper inside (second link, after Wired):



Looks like my lab in the mountains may be a better site. Less seismic pertubations. Far from the coast, almost no traffic, and I can't afford an elevator. Alas, if they put a dozen or two large wind turbines on the ridge, they'll probably screw that up.

"filled with Galinstan™ liquid metal (a commercially available alloy consisting mainly of gallium, indium, and tin). Galinstan™ has a low toxicity and reactivity, so it is often used in place of mercury." I read about the development of this stuff years ago, but was unable to obtain any. I wanted to build an Ampere force manometer (an invention of mine I wanted to try to settle an electrodynamics dispute). Some of the experimenters in the field had been known to use mercury and consequently their mental integrity was suspect.

Just scanning ... am I seeing 1.8 to 1.9+ GHz thru a 25 watt amplifier, typical drives of a few watts? The effects should be stronger at higher frequency if my source is correct. 2.45 GHz at 1.2 kW is pretty easy to come by, although someone may complain if the microwave oven in the break area goes missing.

Torsion setup looks OK. I could rig that magnetic dampener in an afternoon with scrap aluminum and a few magnets. Displacement measurement possibly seismically sensitive and more than a little touchy, but the right idea. System self-calibrates force using electrostatic force and interleaved fins. At a glance it looks like they tested for null conditions (dummy load instead of the thruster checked). Also sounds like they were running at high vacuum. Turbopumps, outgassing for a couple of days ... I'll read in more detail.


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