Sticking another idea into the public domain.

[SANEAlex]

[pauldear]

It's a cool technology. What worries me, though, is that its effectiveness seems to scale with the size of the object, so you'd need something pretty massive before thrust/payload broke even.

There are also a few cool YouTube videos listed under "electrohydrodynamic thrust", mostly showing small aluminium foil structures whizzing around on the end of tethers that carry the high voltage.

Cheers,
Paul

[SANEAlex]

[pauldear]

Hmm - I like the idea of a self-circularizing orbit, that's neat!

Cheers,
Paul

[SANEAlex]

[pauldear]

I don't know enough to comment on the technical problems, but I wonder what the efficiency of the EHD is? I guess it should be pretty high, inasmuch as if you get all your ions going in the right direction, there's nowhere for the electrical energy to go except into propulsion.

To me, the main problem is that this sort of system (both EHD and atmosphere-bouncing) is very difficult to test and optimise, since it all depends very heavily on interactions with a very thin atmosphere at high speeds. In contrast, high-impulse methods (ie, traditional rockets and the like) can have their behaviour predicted fairly closely, and ground-based tests give you a lot of useful data.

Overall, I very much like the idea of "flying" a spaceship as close as possible to the edge of space, especially if solar power can be used (a kilowatt per square metre - npt a lot but significant). I'm by no means qualified to evaluate possible schemes, but flying is a fairly gentle, manageable technology which, if you scale the velocities as the atmosphere thins (reducing lift per unit speed, but at the same time reducing drag) ought to get you a long way.