Joe Strout wrote:

[snip]

All that needs to be done is to make the upwards push a greater
impulse than the downwards push - the rocket would essential jerk its
way upwards - after all there is no "conservation of displacement"
with such an inertial system.

There is conservation of momentum, and you just proposed to violate it.
This is a stiction (static friction) drive, and works only when in
contact with some other body. The movement comes from the difference
between static and sliding friction. And, BTW, if you want a drive that
only works when in contact wiith a larger body, there are much better
ones (the wheel comes to mind).

Such a drive is utterly useless in space, however. Jerk your rocket
around all you want, it'll never make any net progress at all.

Cheers,
- Joe


One more reason for cheap access at least to LEO: Everyone who thinks
they've got a reactionless drive can take a prototype up there, put it
outside the ship, and then they can put up, or shut up.

(I know, there are cheaper ways of doing this [suspend it, and see if
you get a unidirectional deflection, instead of gyrating or oscillating
around the perpindicular], but my approach is instinctively unambiguous.
This, after all, is where the thing is supposed to work.)

It would be even more interesting, if the losers have to find their
own way back to the ground.....