I believe a gravity turn is more efficient (complete your turn between 10km and 70km -- burn until you reach your desired apoapsis, then circularize). Wikipedia explains it pretty well: A gravity turn or zero-lift turn is a maneuver used in launching a spacecraft into, or descending from, an orbit around a celestial body such as a planet or a moon. It is a trajectory optimization that uses gravity to steer the vehicle onto its desired trajectory. It offers two main advantages over a trajectory controlled solely through vehicle's own thrust. Firstly, the thrust doesn't need to be used to change the ship's direction so more of it can be used to accelerate the vehicle into orbit. Secondly, and more importantly, during the initial ascent phase the vehicle can maintain low or even zero angle of attack. This minimizes transverse aerodynamic stress on the launch vehicle, allowing for a lighter launch vehicle.