# Shawyer's EMdrive

#### Kosta

http://www.shelleys.demon.co.uk/fdec02em.htm" [Broken]
And check out new scientist's issue last week if you have subscription, http://www.newscientist.com/data/images/archive/2568/25681401.jpg" [Broken]

What do you guys think of the science behind this? He says with a superconducting cavity he could get 30,000 newtons per kilowatt - enough to lift(hover) a large car.

He says it wouldn't be useful for propulsion but if it can lift a car againts gravity for a long period of time.. remove that gravity (such as in space) would it not go flying? And would it not be able to achieve at least 1g acceleration? (ie eath-to mars(median 280mil km) in just under 4 days including turnaround)

Thanks, (whats my nick again?)

P.S btw sry if this has been posted before, I searched.. nothing .. im new..

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#### JoAuSc

It seems to violate conservation of momentum, but I'm a bit rusty as to taking into account the momentum contained in the EM field. Also, I don't think the radiation pressure on one side of the cavity would be smaller than the other since the effective areas are the same once you take into account the sloped inner surface.

#### russ_watters

Mentor
From the diagram, it is pretty simple to understand why it doesn't work: radiation pressure is what he's talking about and pressure is force over area. The pressure on one side would be higher than the other, but the net force is the same in both directions.

In the photo of his demonstration device, I notice there is something sitting under the side of the balance that his device is sitting on...

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#### carmicheal99@ya

What does Lorentz Force have to do with this machine? In his paper, he uses a shortened version for the force which neglects the cross-product between velocity and the magnetic field. In Shawyer's formulation the force is just placed there without regard for the direction.

#### Ivan Seeking

Staff Emeritus
Gold Member
By all appearances, this is a crank claim and not worth discussing. The paper has never been published in a peer-reviewed journal.

This thread should have been locked long ago.

"Shawyer's EMdrive"

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