So, I mounted 4 radial turbojets on my rocket with the intent of getting up to 15000m, ditching the engines, and going up the rest of the way on rockets. It works...kind of. Only problem is that the turbojets tend to spin the rocket when I turn off SAS - even with fins, so I'm doing my gravity turn after I ditch the engines. Is this design efficient? Correct me if I'm wrong, but I'm thinking that I'm pretty much getting 15000m worth of altitude 'for free'.