Low cost access to space? Phase three.

Snip

As is pointed out in the Wikipedia article hitsquad referenced, a
reactionless drive is equal to violating conservation of energy. As
a thought experiment, consider one in a frictionless mag lev vacuum tunnel.

No matter what the power consumption is, if you let the velocity get
high enough and lower a wheel connected to a generator, it will
generate more power than it is using for the reactionless drive.

Not saying that reactionless drives can't be made, just pointing out
one of the consequences. I.e., if you have figured out how to do it,
you have also an unlimited energy source out of nowhere.

Keith Henson