Why does a rocket need to be aerodynamically stable?
If the rocket is not stable, there is no reason for it to point in any particular direction and its flight will be erratic and inefficient. If you launch a rocket that is slightly unstable, it will wander in an unpredictable way and is almost funny to watch (assuming that you do this in a sufficiently safe way). For a rocket to be stable, there is a rule of thumb that states that the Centre of Drag (CoD) should be between one and two rocket diameters behind the Centre of Gravity (CoG).
