Thanks for all the help! Over the last few hours I've worked out a lot of what you guys have been saying from experimentation - I spun from a mixture of too much Delta-V and not enough fins, plus that thing wasn't powerful enough anyway. I've noticed that SaS has little effect, I think because that setup has rigid fins (they don't move when I change pitch/yaw/roll) and the engine has no vectoring. Am I right in saying this or am I missing something? One more question, can someone explain why this is the case: I'm guessing my CoT should be nearer the bottom of the rocket, and the CoM near the middle? Again, why?