I think those two wing mounted engines may be your issue, they can easily tip your ship over and unbalance it quickly due to their torque on the whole system. Try removing those wing engines. Also, here\'s an example of a working space shuttle, perhaps it could help you out: http://kerbalspaceprogram.com/forum/index.php?topic=12540.0 I would say, remove the air breathing engines, and place your rockets to be side mounted rather than at the bottom of the shuttle.