|“|| SSTO is overrated, payload capability and comfortable seats are all the rage these days.
In 0.25 and 0.90, the Learstar had 6.4 km/s of delta-V when empty, or enough capacity to lift about 40 tons into low Kerbin orbit. In 1.0, it had 5.9 km/s of delta-V when empty, or enough capacity to lift about 75 tons into LKO. (The reduction in delta-V was outweighed by the reduction in delta-V required to make LKO by the aerodynamic update.)
It is recommended to tweak the thrust of the orbiter's main engines to 60% and tweak down the thrust of the Kerbodyne KR-2L engine at the bottom of the large fuel tank during the flight as fuel is being drawn from the tank.