[RightWhale]

I believe it requires a single vehicle.

I believe so, too. They shouldn't do that, limit the approaches to space travel that way. If the contestants could airlaunch, the contest would already be over, probably a year ago. The objective is to get into space, not to build another rocket.

[DoughtyOne]

I'm not convinced you are wrong. My personal opinion is that the piggy-back system is a half-measure. I may be wrong with regard to that.