CG and CP?

You state that CG should be above CP, but this terminology is slightly ambiguous. Usually people say that the CG should be forward of the CP or the CP should be aft of the CG. I realize these are not terms everyone knows, but once you understand them it makes things more clear.

mikeasaurus12 days ago

True, but I am keeping this class very simple in concept and vocabulary. Rocketry is such a deep field with so many more forms than what I show here.

NikhilK12319 days ago

CG:Center of Gravity

CP:Center of pressure

The reason he uses the term 'above' is because the rocket is moving vertically up.If the CG is above the CP,the rocket can maintain a state called 'stable equilibrium',such that if it tilts, it turns back to its vertical up state.This is similar to case when the north pole of a magnet pointing north is given a slight push(it turns back to north). If CG were below CP,we would have 'unstable equilibrium'. This is dangerous for a rocket!In this case any small disturbance(tilt) can flip the rocket from up to down just like a magnet flips orientation when you make the north pole point south.