In reply to Wesley Bruce's message of Fri, 15 Sep 2006 16:41:50 +1000: Hi, [snip] >A stationary emdrive can still push a ship in a given direction. It >becomes an inertial anchor. An inertial anchor resists being moved but >does not move itself. You can push down or back on it and it wont move >but pulling upon it and it moves freely. A craft with an inertial anchor >on it can jack forward against the mass and drive force of the anchor. >It can then pull the anchor forward pulling against only the mass of the >drive. The result is a dynamic mechanical asymmetry. The emdrive would >probably be jacked back and forth by a linear motor or a crank driving a >rod. For smooth operation you need several Inertial Anchors cycling out >of phase to produce uniform forward momentum. Interestingly you could >put emdrive inertial anchors on the ends of a set of oars and simply >"row" through outer space. A vac-suit would be advisable. [snip] As I understand it however, the actual drive in question is not an inertial anchor. It's just that the force drops off as it starts to accelerate. This is because the force depends upon a huge microwave density in the cavity, and as energy is consumed in accelerating the device, it is drawn from this microwave energy. However there is no reason why it shouldn't provide a continuous acceleration force if the energy in the cavity is replaced as fast as it is used.
It's like pouring water into a leaky bucket. If your pour water in as fast as it leaks out, then the bucket stays full. Regards, Robin van Spaandonk http://users.bigpond.net.au/rvanspaa/ Competition provides the motivation, Cooperation provides the means.
