T' mistaken belief that a rocket will be stable if t' motor is ABOVE t' rocket's center o' mass, so that t' rocket is "hanging" below t' center o' thrust and will try t' remain upright, like a hangin' pendulum. Begad! It doesn't work; even Robert Goddard learned that t' hard way. See t' followin' links for more information: http://en.wikipedia.org/wiki/Pendulum_Rocket_Fallacy and http://www.geocities.com/jim_bowery/pendrock.html