Orbiter One Program
Taking off from the trolley is tricky yet, I will leave this subject to a new post - there're still improvements to be made on the proceedings.
But one you get airborne, this fat lady flies pretty well.
The best ascent regime is still RiP*, but basically starts to climb slowly once you reach TWR > 1.5, and do it aggressively as you are near Mach 4 to avoid begin fried.
RiP : Research in Progress