Thrusters On! Reactionless Spacecraft Engines?

Discussion in 'General Science & Technology' started by Yazata, Nov 20, 2016.

  1. Q-reeus Valued Senior Member

    Under 'Litany of Problems' here:
    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.
    danshawen likes this.
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  3. OceanBreeze Registered Member

    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.
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  5. Walter L. Wagner Cosmic Truth Seeker Valued Senior Member

    Last edited: Nov 26, 2016
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  7. exchemist Valued Senior Member

    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.
  8. Q-reeus Valued Senior Member

    A compass needle probably too high tech for those bods

    Please Register or Log in to view the hidden image!

    . 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.
    OK then fair enough - we all have our own style.
    danshawen likes this.
  9. Yazata Valued Senior Member

    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.

    I'm still not completely convinced.
    Last edited: Dec 20, 2016
  10. Q-reeus Valued Senior Member

    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.
  11. paddoboy Valued Senior Member


    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.
  12. OceanBreeze Registered Member

    Looks like I was right.

    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.
  13. Q-reeus Valued Senior Member

    Old news:
    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.
  14. OceanBreeze Registered Member

    Did you read Tajmar's paper?


    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: [accessed Jul 31 2018].

    Pretty much what I have said all along.
  15. Q-reeus Valued Senior Member

    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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