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Nasa's EM Drive: Peer Reviewed Paper

 
 
Reply Sat 19 Nov, 2016 04:01 pm
http://www.sciencealert.com/it-s-official-nasa-s-peer-reviewed-em-drive-paper-has-finally-been-published

After months of speculation and leaked documents, NASA's long-awaited EM Drive paper has finally been peer-reviewed and published. 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.

But, there's a not-small problem with the system. It defies Newton's third law, which states that everything must have an equal and opposite reaction.

According to the law, for a system to produce thrust, it has to push something out the other way. The EM Drive doesn't do this.

Yet in test after test it continues to work. Last year, NASA's Eagleworks Laboratory team got their hands on an EM Drive to try to figure out once and for all what was going on.

And now we finally have those results.
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contrex
 
  1  
Reply Sat 19 Nov, 2016 04:29 pm
@edgarblythe,
edgarblythe wrote:
According to the law, for a system to produce thrust, it has to push something out the other way. The EM Drive doesn't do this.

I thought that it is simply that if it does work, it is pushing something out, we just don't know exactly what it is. Probably photons, the same principle as the solar sail, as (in fact) scientists at Helsinki University have theorized, and as (in fact) an earlier (June 2016) Sciencealert article with nearly the same wording said.

http://www.sciencealert.com/new-paper-claims-that-the-em-drive-doesn-t-defy-newton-s-3rd-law-after-all


edgarblythe
 
  1  
Reply Sat 19 Nov, 2016 04:58 pm
@contrex,
I just hope they are right that it is going to work in space.
0 Replies
 
TomTomBinks
 
  1  
Reply Sat 19 Nov, 2016 05:47 pm
@edgarblythe,
There was a discussion (and a thorough debunking ) of this technology on this forum earlier this year.
0 Replies
 
edgarblythe
 
  1  
Reply Sat 19 Nov, 2016 06:34 pm
Well it's too late to delete the thread.
dlowan
 
  1  
Reply Sat 19 Nov, 2016 07:33 pm
@edgarblythe,
I just read it had been retested and it works? Sounds dipshit crazy to me
edgarblythe
 
  1  
Reply Sat 19 Nov, 2016 08:15 pm
@dlowan,
Well, I grew up reading Phillip Jose Farmer and watching Disney cartoons. Everything seems possible to me.
TomTomBinks
 
  1  
Reply Sat 19 Nov, 2016 10:01 pm
@edgarblythe,
It would be awesome if it would work. I'm no physicist, so if the report is full of sciency sounding words I'm all for it. It's just that I brought this up a while back full of hope for the near future of space travel and those actually knowledgeable in physics gave a list of reasons that this was BS.
farmerman
 
  1  
Reply Sun 20 Nov, 2016 05:27 am
@TomTomBinks,
I think it needs some real scale testing. I always thought that the reason for the conflict with "action reaction" was that the propogating wave guides do not EVER maintain parallel positions in order to generate the photon pairs. This chops the efficiency by huge amounts.

Course that was last years papers
rosborne979
 
  1  
Reply Sun 20 Nov, 2016 07:03 am
@edgarblythe,
What is NASA Eagleworks Lab? Is that a department in NASA or is it a consulting agency?
0 Replies
 
edgarblythe
 
  1  
Reply Sun 20 Nov, 2016 07:23 am
http://www.forbes.com/sites/briankoberlein/2016/11/19/nasas-physics-defying-em-drive-passes-peer-review/#61b451f876e2
Forbs website:
It’s important to note that passing peer review means that experts have found the methodology of the experiments reasonable. It doesn’t guarantee that the results are valid, as we’ve seen with other peer-reviewed research such as BICEP2. But this milestone shouldn’t be downplayed either. With this new paper we now have a clear overview of the experimental setup and its results. This is a big step toward determining whether the effect is real or an odd set of secondary effects. That said, what does the research actually say?

The basic idea of the EMDrive is an asymmetrical cavity where microwaves are bounced around inside. Since the microwaves are trapped inside the cavity, there is no propellent or emitted electromagnetic radiation to push the device in a particular direction, standard physics says there should be no thrust on the device. And yet, for reasons even the researchers can’t explain, the EM Drive does appear to experience thrust when activated. The main criticism has focused on the fact that this device heats up when operated, and this could warm the surrounding air, producing a small thrust. In this new work the device was tested in a near vacuum, eliminating a major criticism.

The relation of thrust to power for the EM Drive. Credit: Smith, et al.
The relation of thrust to power for the EM Drive. Credit: Smith, et al.

What the researchers found was that the device appears to produce a thrust of 1.2 ± 0.1 millinewtons per kilowatt of power in a vacuum, which is similar to the thrust seen in air. By comparison, ion drives can provide a much larger 60 millinewtons per kilowatt. But ion drives require fuel, which adds mass and limits range. A functioning EM drive would only require electric power, which could be generated by solar panels. An optimized engine would also likely be even more efficient, which could bring it into the thrust range of an ion drive.
contrex
 
  1  
Reply Sun 20 Nov, 2016 08:04 am
Grahn, Annila and Kolehmainen at the University of Helsinki have published a paper "On the exhaust of electromagnetic drive" where they suggest that the measured effect could be produced by paired opposite-phase photons being ejected from the cavity. (i.e. it's a photon rocket). These would cancel out each other's electromagnetic fields and thus be invisible from an electromagnetic point of view, but, they say, the photons do not vanish.They emphasise that their "proposal for the paired-photon exhaust is by no means an exclusive explanation".

http://scitation.aip.org/content/aip/journal/adva/6/6/10.1063/1.4953807

Long thread at nasaspaceflight.com

https://forum.nasaspaceflight.com/index.php?topic=39772.3220

and another:

https://forum.nasaspaceflight.com/index.php?PHPSESSID=llr7dvib5u129uq52ga4bfdf82&topic=39772.4200

contrex
 
  1  
Reply Sun 20 Nov, 2016 08:05 am
@edgarblythe,
edgarblythe wrote:
It’s important to note that passing peer review means that experts have found the methodology of the experiments reasonable. It doesn’t guarantee that the results are valid

This.
0 Replies
 
edgarblythe
 
  1  
Reply Sun 20 Nov, 2016 08:09 am
The Advanced Propulsion Physics Laboratory at NASA's Johnson Space Center, also known as "Eagleworks", is a small research group investigating a variety of fringe theories regarding novel forms of spacecraft propulsion.

Their research includes the investigation of the EmDrive[1] and the Quantum Vacuum Plasma Thruster,[2] both claimed by their inventors to be reactionless drives.

Their principal investigator is Dr. Harold "Sonny" White.
https://en.wikipedia.org/wiki/Advanced_Propulsion_Physics_Laboratory
0 Replies
 
TomTomBinks
 
  1  
Reply Sun 20 Nov, 2016 08:17 am
@farmerman,
Are the photons propagated from the outer surface of the housing?
contrex
 
  1  
Reply Sun 20 Nov, 2016 08:19 am
@TomTomBinks,
TomTomBinks wrote:

Are the photons propagated from the outer surface of the housing?

No.
0 Replies
 
farmerman
 
  1  
Reply Sun 20 Nov, 2016 08:50 am
@contrex,
Quote:
They emphasise that their "proposal for the paired-photon exhaust is by no means an exclusive explanation".
ah yes, I see. I forgot that equations do not necessarily define exclusivity of solution.

0 Replies
 
rosborne979
 
  1  
Reply Tue 22 Nov, 2016 07:56 pm
A nice analysis by ARS Technica: http://arstechnica.com/science/2016/11/nasas-em-drive-still-a-wtf-thruster
0 Replies
 
 

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