Thrusters On! Reactionless Spacecraft Engines?

OceanBreeze said:
The size of the thrust they are getting can be satisfactorily explained by the Lorentz force on the apparatus reacting with the earth’s magnetic field.
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Under 'Litany of Problems' here: http://www.astronomy.com/news/2016/11/emdrive-thruster-cleared-first-hurdle
Tests of the device have been subject to some glaring flaws, and one Chinese team was forced to retract the results of a 2012 experiment after concluding that they were due to thermal expansion in the test device.
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Some researchers do bungle things. But in this case, all that was needed was to actually read the article linked to in #1. Under 8 Error Sources, item 3):
The third error is magnetic interaction, which has the potential for a false positive resulting from dc currents in power cables interacting during test article operation with ambient magnetic fields (e.g., local Earth field, magnetic damper) to generate a torque displacement on the pendulum. All dc power cables are a twisted pair or twisted shielded pair to minimize magnetic interaction. The test article is tested in forward, reverse, and null thrust orientations, but dc power cable routing and orientation is the same for all three configurations (power cables come in from the top of the test article), meaning any false positives will be the same magnitude and polarity for all three tests. This is not observed during the test campaign.
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Just one among the quite thoroughly list of items in that list. Checking things out and thinking things through before authoritatively postulating can pay dividends.
 
Q-reeus said:
Under 'Litany of Problems' here: http://www.astronomy.com/news/2016/11/emdrive-thruster-cleared-first-hurdle

Some researchers do bungle things. But in this case, all that was needed was to actually read the article linked to in #1. Under 8 Error Sources, item 3):

Just one among the quite thoroughly list of items in that list. Checking things out and thinking things through before authoritatively postulating can pay dividends.
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I did read the paper and I am not convinced the measures they employed to eliminate interaction with the earth’s magnetic field (such as using double shielded cables) are sufficient. They make no mention of shielding the magnetron itself! One simple thing they can do is place a magnetic compass needle near the device before turning it on. If the needle deflects at all, they have a problem.

Who do you suppose was "authoritatively postulating", myself or the researchers?

If you meant me, No, it was more like affably conjecturing.
 
Walter L. Wagner said:
Very interesting analysis. This makes sense. I don't see it was eliminated in their discussion. First year physics, as well


This Rossi case should prove interesting:

http://ecatnews.com/?p=2686
Rossi is suing his partners for fraud (?!).

https://www.pacermonitor.com/public/case/11135976/Rossi_et_al_v_Darden_et_al#

http://www.e-catworld.com/wp-content/uploads/2016/04/Leonardosuit01-main.pdf
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Of course it doesn't bloody work. This guy has been stringing people along for years with no proper results. All this litigation just distracts attention from the failure of this thing.
 
OceanBreeze said:
I did read the paper and I am not convinced the measures they employed to eliminate interaction with the earth’s magnetic field (such as using double shielded cables) are sufficient. They make no mention of shielding the magnetron itself! One simple thing they can do is place a magnetic compass needle near the device before turning it on. If the needle deflects at all, they have a problem.
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A compass needle probably too high tech for those bods :biggrin:. Seriously though, that possibility - appreciable coupling between DC feed-currents & Earth's magnetic field, can easily be eliminated. Ask yourself; will force be directly or quadratically proportional to current? Now go check what is the experimental and theoretical relation between cavity rms currents and 'anomalous' thrust. I get the impression you are up to now seeing the resolution.
Who do you suppose was "authoritatively postulating", myself or the researchers?

If you meant me, No, it was more like affably conjecturing.
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OK then fair enough - we all have our own style.
 
The Chinese say that they have been experimenting with reactionless EM drives for some time and currently have one in low earth orbit. They are getting thrust from it but not much (in the scale of < 10 millinewtons/KW) but want to get it up to about 100 millinewtons/KW. So they are experimenting with different sized cavities and so on.

http://www.dailymail.co.uk/sciencet...-impossible-engine-says-s-orbiting-Earth.html

http://www.popsci.com/emdrive-engine-space-travel-china-success

I'm still not completely convinced.
 
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Yazata said:
The Chinese say that they have been experimenting with reactionless EM drives for some time and currently have one in low earth orbit. They are getting thrust from it but not much (in the scale of < 10 millinewtons/KW) but want to get it up to about 100 millinewtons/KW. So they are experimenting with different sized cavities and so on.

http://www.dailymail.co.uk/sciencet...-impossible-engine-says-s-orbiting-Earth.html

http://www.popsci.com/emdrive-engine-space-travel-china-success

I'm still not completely convinced.
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When the history of this strange chapter is finally written, the record will read "A scientific and technological breakthrough originating from wrong premises." Shawyer's theory is quite wrong, but he managed to stumble onto something real despite that.
 
http://www.sciencealert.com/china-is-claiming-it-s-already-started-testing-an-em-drive-in-space

China claims it's already started testing an EM Drive in space

The whole world got excited last month when NASA published the first peer-reviewed paper on the 'impossible' electromagnetic, or EM, Drive, which appears to somehow defy physics by producing thrust without a propellant.

Their verdict was that it seems to work, although a lot of physicists still think the results are flawed. But now researchers in China have announced that they've already been testing the controversial drive in low-Earth orbit, and they're looking into using the EM Drive to power their satellites as soon as possible.

Big disclaimer here - all we have to go on right now is a press conference announcement and an article from a government-sponsored Chinese newspaper (and the country doesn't have the best track record when it comes to trustworthy research).

So until we see a peer-reviewed paper, we really can't say for sure whether the researchers are even testing the drive in space, let alone what their results have shown.
http://www.sciencealert.com/china-is-claiming-it-s-already-started-testing-an-em-drive-in-space
 
OceanBreeze said:
I can’t offer any specific details; all I am saying is the magnitude of the measured force is within a range that is not disproportionate with the strength of the earth’s magnetic field and the power being used. To drive the DUT

The Tesla has the dimensions N*s / C*m where N is Newton, s second, C coulomb, m meter.

Lorentz Force = I L T, where I is current in coulombs/second and L is length in meters. T is Tesla as defined above

The observed power/force ratio was on the order of ~ 0.001 N / 1KW of RF power. The DC power into the magnetron would be about 1500 Watts, drawing 10 Amps. Taking the magnetic field strength of the earth to be a nominal 50 uT and 1 meter conductor length. F = 0.0005 N fully 50% of what was measured.

If you remember the neutrino fiasco, it isn’t out of the question the researchers are overlooking this possible source. Since the earth’s magnetic field cannot be shielded from the experiment, it would be interesting to know what steps were taken to prevent this Lorentz force from interfering with the experimental results.

I suppose Rossi is still thriving on the theory of P.T. Barnum "There's a sucker born every minute"
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Looks like I was right.

https://www.forbes.com/sites/starts...ace-engine-really-is-impossible/#540bf27c3a00

with a properly shielded apparatus, with no additional electromagnetic fields induced by the wires, there is no observed thrust at any power. They conclude that these induced fields by the electrical wires, visibly present in the other setups, are the likely culprit for the observed, unexplained thrust:

Our results show that the magnetic interaction from not sufficiently shielded cables or thrusters are a major factor that needs to be taken into account for proper µN thrust measurements for these type of devices.
 
OceanBreeze said:
Looks like I was right.

https://www.forbes.com/sites/starts...ace-engine-really-is-impossible/#540bf27c3a00

with a properly shielded apparatus, with no additional electromagnetic fields induced by the wires, there is no observed thrust at any power. They conclude that these induced fields by the electrical wires, visibly present in the other setups, are the likely culprit for the observed, unexplained thrust:

Our results show that the magnetic interaction from not sufficiently shielded cables or thrusters are a major factor that needs to be taken into account for proper µN thrust measurements for these type of devices.
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Old news:
http://www.sciforums.com/posts/3525611/
http://www.sciforums.com/posts/3519220/
Only if feed current is directly proportional to cavity rms power would it be possible for measured force be explained by interaction with Earth's magnetic field. Is that known to be the case in Tajmar's setup?
And for it to be a general explanation, the same (partly unshielded) feed-current/Earth's B-field interaction would have to be present, and to the same extent, in all the other tests done by other parties.
 
Q-reeus said:
Old news:
http://www.sciforums.com/posts/3525611/
http://www.sciforums.com/posts/3519220/
Only if feed current is directly proportional to cavity rms power would it be possible for measured force be explained by interaction with Earth's magnetic field. Is that known to be the case in Tajmar's setup?
And for it to be a general explanation, the same (partly unshielded) feed-current/Earth's B-field interaction would have to be present, and to the same extent, in all the other tests done by other parties.
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Did you read Tajmar's paper?

Quote:

This clearly indicates that the “thrust” is not
coming from the EMDrive but from some
electromagnetic interaction. Although we used
twisted or coaxial cables as much as possible, some
magnetic fields will eventually leak through our
cables and connectors. Considering the magnetic
field strength of the Earth’s magnetic field of 48 µT
with an inclination of 70° in middle Europe, a few
centimeters of cables and a current of 2 A (similar to
what is needed to power the amplifier), we obtain
Lorentz forces of a few µN, which is similar to our
observed “thrust” values. We therefore suspect, that
the interaction of the power feeding for the amplifier
with the Earth’s magnetic field masked any real
thrusts that could be below our observed value.

(PDF) The SpaceDrive Project - First Results on.... Available from: https://www.researchgate.net/public..._Results_on_EMDrive_and_Mach-Effect_Thrusters [accessed Jul 31 2018].

Pretty much what I have said all along.
 
OceanBreeze said:
Did you read Tajmar's paper?

Quote:

This clearly indicates that the “thrust” is not
coming from the EMDrive but from some
electromagnetic interaction. Although we used
twisted or coaxial cables as much as possible, some
magnetic fields will eventually leak through our
cables and connectors. Considering the magnetic
field strength of the Earth’s magnetic field of 48 µT
with an inclination of 70° in middle Europe, a few
centimeters of cables and a current of 2 A (similar to
what is needed to power the amplifier), we obtain
Lorentz forces of a few µN, which is similar to our
observed “thrust” values. We therefore suspect, that
the interaction of the power feeding for the amplifier
with the Earth’s magnetic field masked any real
thrusts that could be below our observed value.

(PDF) The SpaceDrive Project - First Results on.... Available from: https://www.researchgate.net/public..._Results_on_EMDrive_and_Mach-Effect_Thrusters [accessed Jul 31 2018].

Pretty much what I have said all along.
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After looking through the pdf file you linked to in #31, found the crucial clue p3 there. I now agree there will be no 'reactionless EM cavity thrust' with Tajmar's implementation. Depending on how they mod the cavity next time, that may change. Sorry but won't divulge what the key factor re my updated assessment is.
 
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