My 12 year old asked me this question. I have a MS in Mechanical Engineering, so I can usually answer his physics questions, but this one stumped me. When lifting off, why do most rockets turn close to horizontal almost immediately? Of course we know they need mostly horizontal speed to achieve orbit, but they also need altitude. If the rocket gained all it's altitude first, vertically, and then made a 90deg turn to the horizontal and then sped up horizontally, the majority of it's high speed flight would be outside of the Earth's atmosphere, greatly decreasing air resistance and wasted energy. Wouldn't this be much more energy efficient?