The Fact and Fiction of the NASA EmDrive Paper Leak

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A NASA paper outlining work that appears to substantiate the EmDrive concept that involves the production of a thrust in a way that violates the laws of physics was leaked last week, and this story tries to figure out what has been learned.

To me, the key is this paragraph:

In essence, the NASA EmDrive in the paper consists of a closed copper cone, the inside of which is being bombarded with microwaves. To test the EmDrive, the researchers powered it with 40, 60, and 80 watts and found that it generated up to 58, 128, and 119 micronewtons of thrust, respectively. Given that this “anomaly” was still observed by White and his colleagues after accounting for error, this suggests that the results of the experiment show an EmDrive is indeed possible.

Based on these results, the researchers estimated that their contraption would be capable of generating approximately 1.2 millinewtons of thrust per kilowatt were they to scale up the power input. To put this in perspective, the Hall thruster—one of the most powerful in development and powered by ejecting plasma—generates about 60 millinewtons of thrust per kilowatt. [emphasis mine]

Interestingly , the article did not comment on how little thrust this EmDrive test produced. This tiny amount, however, to me suggests strongly that what they are measuring is some outside force acting on the drive that they have missed that would invalidate all the theories listed in the article. And even if the thrust drive does prove a new component of fundamental physics, as suggested in the article, the system simply doesn’t appear to produce enough thrust to make it practical.



  • Simon Mytton

    If this is a real phenomenon could these be used in place of reaction control wheels (which seem to be forever breaking down)? Would they produce enough thrust for this purpose?

  • Brendan

    Even if the EM drive is only producing 2% of the thrust of a hall drive, it doesn’t need mass. That is a big deal. Station keeping, exploration, all open up.

    You should check out the physics from the edge web site. Its interesting that he has developed a theory that flushes dark matter and seems to predict what the em drive is doing…

  • Alex

    Bendan: Also a flash-light (or a laser) produce (very small) thrust and does not propellant. Under ideal condition you can produce 1 Newton thrust by application of 300 MW (or 1 Milli-Newton by 300 KW, or 1 Micro-Newton by 300 W). So EM drive looks not very strange.

  • Frank

    An 11 x 11 meter solar panel that could generate 1.5kW of power for a scaled up engine in the example would produce about 1mN of force from the solar wind alone creating a vector against, or entirely canceling out the engine thrust.

  • Brendan

    Alex –
    True. But the photon thrust is 360 times less that the measured output here. And this is with an experimental device. That is a big deal.

    I’ve been following McCulloch’s work and its completely in keeping with what my college relativistic physics prof taught – that inertia is approaches infinity at light speed, and that mass becoming infinite as it approaches the speed of light is a myth. That McCulloch has placed this concept in a theory that seems to explain concepts from the EM drive to being able to describe galactic movements without the need for dark matter is actually an even bigger deal. That the EM drive can be predicted with his theory seems to give it credence.

    That said, people keep trying to kill off the EM drive, and it hasn’t happened yet. Cold fusion was killed off much faster. I say we give it time and see what happens.

  • Alex

    Brendan: Okay, 360-times is quite a lot, it requires an explanation.

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