EmDrive Space Engine Passes Peer Review

[Stardust]

http://www.space.com/34797-impossible-sp...ished.html

http://arc.aiaa.org/doi/full/10.2514/1.B36120

Surprised no one's been talking about this on here already. What are your thoughts?

[Drashner1]

It's interesting - although my first inclination is to still take a 'wait and see' attitude to it. As the space.com article says, it's not 100% clear that there wasn't some other effect being seen here. It's also not clear to me that, even if this is a real thing, that it would be something that could actually be used to either:

a) propel a spacecraft

b) propel a spacecraft to a significant velocity

c) outperform other, more conventional, propulsion methods once all is said and done.

So, worth keeping an eye on (wait and see), but not worth starting to breath too heavily over just yet.

My 2c worth,

Todd

[stevebowers]

This drive produces a tiny, almost undetectable thrust, assuming it works at all. You'd need a lot of power to give a spaceship a detectable acceleration, but that is also true of a hypothetical photon drive.

[iancampbell]

This drive produces a tiny, almost undetectable thrust, assuming it works at all. You'd need a lot of power to give a spaceship a detectable acceleration, but that is also true of a hypothetical photon drive.

Quite right. Two points:

Thrust seems to depend entirely on the amount of power poured into the gadget. Therefore, maximising acceleration needs a power supply that's light for the power delivered. One solution with near-future technology might be a long boom with the required fission reactor on the end of it, and shielding only directly between payload and power supply. Or, slightly more speculatively, a Polywell or DPF fusion reactor.

And the rather tiny thrust might be improved upon. If this thing works at all, it works on a physical principle not currently known. But tinkering might improve the thrust to power ratio, even if the principles are not known. An imperfect analogy is the steam engine, which was improved in efficiency by at least an order of magnitude well before the physics of heat engines was developed in any formal way.

[Rynn]

Speaking to some physics friends this paper seems highly dubious. It mentions possible variables like out-gassing, wind and seismic activity but doesn't do much to measure and characterise them. The measurements are more sensitive than the machine is capable of, the statistics are apparently problematic, they only have three hours of data despite months of testing and the journal has an impact factor of 1.2! The last point makes me wonder how many journals rejected the paper until this one accepted it.

[selden]

Unfortunately, it seems to me that measuring this effect has all the disadvantages that the attempts to measure cold fusion had. If it exists, it's so tiny that it's going to be extremely difficult to separate it from all the background effects.