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The proposed radio frequency (RF) resonant cavity thruster is unlike conventional thrusters and uses no reaction mass and emits no directional radiation. Designed using principles that are not supported by prevailing scientific theories, it apparently violates the law of conservation of momentum. The EmDrive, has roiled the aerospace world for the several years now, ever since it was proposed by British aerospace engineer Robert Shawyer. The essence of the claim is that by bouncing microwaves in a truncated cone, thrust will be produced out the open end. Most scientists have snorted at the idea, noting correctly that such a thing would violate physical laws. However, prestigious organizations like NASA have replicated the results showing thrusts.
MIT Technology Review has some reasoning on the subject, (possibly pay-walled) with a picture of the device. It's supposedly the so called unruh effect at play. When NASA tested the device, they measured with input of 17 W an average thrust of 91 µN (5.4 µN/W). A Chinese team used 2500 W and measured a thrust of 720 mN (288 µN/W). The expected radiation pressure is closer to 0.003 µN/W.
(Score: 2) by bitstream on Friday April 22 2016, @07:57AM
3 MWe far out in space means either dangerous fuel or fusion reactor (He3?) that don't work yet. So neat concept but not feasible. But orbiting between the asteroid belt and the sun, probably works. And unlike that ion drive, no refueling should be needed.
But if we get any Polywell reactor or similar to work.. then... Here we come! ;)
I wonder how fast Mars can be reached with these things pushing constantly?
(Score: 3, Insightful) by jcross on Friday April 22 2016, @03:30PM
I'ts also possible that the design under test is way less efficient than it could be. Perhaps if we understood why it worked, we could get more thrust for the power. The car analogy would be seeing a Newcomen engine (https://en.wikipedia.org/wiki/Newcomen_atmospheric_engine) and saying there's no way that's efficient enough to power the horseless carriages of the future, you'd need a massive and dangerous boiler, etc.