re: Whatever happened to the Dean Drive?.
Didn't really go anywhere. There are simple tests a "reactionless drive" needs to pass, not least the pendulum test, and nobody has.
What's really annoying are all the people who claim that they are just a few thousand dollars away from a "working model." If I had a principle that worked, either for space drives or "free" energy, you'd better believe I could figure out a way to raise twenty thousand or whatever.
When somebody comes into my office, and floats a briefcase through the air across the table, we'll talk.