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posted by cmn32480 on Tuesday November 22 2016, @03:21PM   Printer-friendly
from the that-still-doesn't-mean-it-will-work dept.

After months of speculation and leaked documents, NASA's long-awaited EM Drive paper has finally been peer-reviewed and published [open, DOI: 10.2514/1.B36120] [DX]. And it shows that the 'impossible' propulsion system really does appear to work. The NASA Eagleworks Laboratory team even put forward a hypothesis for how the EM Drive could produce thrust – something that seems impossible according to our current understanding of the laws of physics.

In case you've missed the hype, the EM Drive, or Electromagnetic Drive, is a propulsion system first proposed by British inventor Roger Shawyer back in 1999. Instead of using heavy, inefficient rocket fuel, it bounces microwaves back and forth inside a cone-shaped metal cavity to generate thrust. According to Shawyer's calculations, the EM Drive could be so efficient that it could power us to Mars in just 70 days.

takyon: Some have previously dismissed EmDrive as a photon rocket. This is addressed in the paper along with other possible sources of error:

The eighth [error:] photon rocket force, RF leakage from test article generating a net force due to photon emission. The performance of a photon rocket is several orders of magnitude lower than the observed thrust. Further, as noted in the above discussion on RF interaction, all leaking fields are managed closely to result in a high quality RF resonance system. This is not a viable source of the observed thrust.

[...] The 1.2  mN/kW performance parameter is over two orders of magnitude higher than other forms of "zero-propellant" propulsion, such as light sails, laser propulsion, and photon rockets having thrust-to-power levels in the 3.33–6.67  μN/kW (or 0.0033–0.0067  mN/kW) range.

Previously: NASA Validates "Impossible" Space Drive's Thrust
"Reactionless" Thruster Tested Again, This Time in a Vacuum
Explanation may be on the way for the "Impossible" EmDrive
Finnish Physicist Says EmDrive Device Does Have an Exhaust
EmDrive Peer-Reviewed Paper Coming in December; Theseus Planning a Cannae Thruster Cubesat


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  • (Score: 0) by Anonymous Coward on Tuesday November 22 2016, @04:05PM

    by Anonymous Coward on Tuesday November 22 2016, @04:05PM (#431280)

    Would this type of engine only work in space, or could you also use it on earth (e.g. on an aircraft or (hover)boat)?

  • (Score: 2) by MrGuy on Tuesday November 22 2016, @04:18PM

    by MrGuy (1007) on Tuesday November 22 2016, @04:18PM (#431293)

    Short answer? Yes, but no. You could use it, but it's incredibly inefficient.

    The amount of thrust is INCREDIBLY small. The devices being tested have thrust measured around 0.001 Newton per kilowatt of power. That's about enough thrust to life a grain of rice off a table, for a kilowatt of input power. That's many, many, many orders of magnitude less force than you'd get with an electric motor.

    The big deal here is that this is force we can get in a vacuum, without propellant. The need to carry (and eventually exhaust the supply of) propellant is one of the hardest problems in rocketry. So the ability to generate thrust without carrying around propellant is a huge advance.

    • (Score: 2) by VLM on Tuesday November 22 2016, @05:12PM

      by VLM (445) Subscriber Badge on Tuesday November 22 2016, @05:12PM (#431338)

      That's about enough thrust to life a grain of rice off a table

      If you could project that force or field, its interesting to consider that a commercial success on the ground might be a force thats un-noticable to anything bigger than a butterfly but covers an area the size of a back yard patio with a force stronger than a mosquito can fly against. Or a force that pisses off mosquitos so they fly away.

      You can just use an electric fan like we did when we were kids and those keep the bugs away and on a hot summer night they keep you cool out on the deck/patio probably for less electrical power but a no moving parts gadget might sell to Dyson type customers.

      Also you could make a tiny little hole in the thruster's waveguide and provide a couple KW so the kids could roast marshmelons (what maybe 1% of SN is going to get that reference? Thats an old movie now...)

      • (Score: 2) by MrGuy on Tuesday November 22 2016, @06:02PM

        by MrGuy (1007) on Tuesday November 22 2016, @06:02PM (#431371)

        Yeah, but now you're talking about a completely different theoretical device.

        One of the things that has people so flummoxed about this device is that it appears to produce thrust with no exhaust. It appears to violate conservation of momentum. So, there's no "force" from the exhaust to use like this.

        Even if you did have a useable exhaust force, this method is an incredibly inefficient way to generate it. You're much better off using a physical device like a fan to produce the effects you're describing.

        • (Score: 2) by VLM on Tuesday November 22 2016, @09:26PM

          by VLM (445) Subscriber Badge on Tuesday November 22 2016, @09:26PM (#431495)

          Yes but it would be really, really cool...

  • (Score: 0) by Anonymous Coward on Tuesday November 22 2016, @04:24PM

    by Anonymous Coward on Tuesday November 22 2016, @04:24PM (#431301)

    Anywhere you can turn it on. But low thrust means space is likely where it would be useful.

    • (Score: 3, Funny) by DannyB on Tuesday November 22 2016, @04:31PM

      by DannyB (5839) Subscriber Badge on Tuesday November 22 2016, @04:31PM (#431309) Journal

      What about practical low thrust applications on Earth, such as keeping ghosts out of your house?

      (ducks, hides under desk)

      --
      People today are educated enough to repeat what they are taught but not to question what they are taught.
      • (Score: 0) by Anonymous Coward on Tuesday November 22 2016, @06:51PM

        by Anonymous Coward on Tuesday November 22 2016, @06:51PM (#431407)

        I'm pretty sure the desk doesn't protect you from ghosts.

  • (Score: 2) by takyon on Tuesday November 22 2016, @04:30PM

    by takyon (881) <reversethis-{gro ... s} {ta} {noykat}> on Tuesday November 22 2016, @04:30PM (#431308) Journal

    The version NASA is testing is comparable to an ion engine capable of making a sheet of paper flutter at best. Roger Shawyer claims that the second generation of emdrive would make a hovering electric vehicle possible:

    http://www.ibtimes.co.uk/emdrive-roger-shawyer-paper-describing-space-propulsion-uavs-finally-passes-peer-review-1513223 [ibtimes.co.uk]

    Shawyer claims a race is on and the second-generation EmDrive is being developed by several players privately including himself, and the new version of the device would be able to achieve tonnes of thrust (1T = 1,000kg) rather than just a few grams. His paper lays out two specific use cases for the EmDrive, which includes providing a way for the 10 tonne Boeing X37-B space plane to fly into orbit on its own, deliver a payload of two tonnes and come back to Earth on its own. At the moment, the X37-B has to be launched from a rocket, but DARPA is working on a new robotic space plane called the XS-1 that it hopes to flight test in 2017, and Shawyer believes EmDrive could help.

    However, he has now decided that it would be better to focus on putting EmDrive on to unmanned aerial vehicles, with the view to eventually use the technology in the automobile industry to create feasible flying cars. "Our aim at the moment is not to necessarily go for these space applications, because they will take so long to come to fruition. So what we've decided as a company is to forget space, and to go for terrestrial transport business, which is huge," Shawyer told IBTimes UK. "The logic is, if you can lift a vehicle reasonably gently with no large accelerations, then you can manufacture the air frame using much lower technology than would be used on an aircraft."

    http://www.ibtimes.co.uk/emdrive-exclusive-roger-shawyer-confirms-mod-dod-interested-controversial-space-propulsion-tech-1586392 [ibtimes.co.uk]

    Shawyer has continued to develop the EmDrive, and over the last year began hinting that he is working with an unnamed UK aerospace company on a second generation superconducting thruster that will produce thrust many orders of magnitude greater than that observed by Eagleworks or any other laboratory (view his latest patent application here).

    However, he has confirmed that the company he is working with is none other than Gilo Industries Group, the inventors of the personal aviation paramotor vehicle Parajet Skycar, which famously flew TV survivalist Bear Grylls close to Mount Everest in 2007 and is now being developed as an all-terrain flying car. "Gilo Cardozo approached me. I confirm that we are in a joint venture. Universal Propulsion is the name of the joint venture and it's located in Dorset," said Shawyer. "It's a very innovative, modern young company. He has an excellent track record. He employs professional scientists and engineers who reviewed the science of the EmDrive. Like many people who don't say much, these guys go through it very carefully. Gilo has the engineering expertise and resources to do this, so it's a good match between us."

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