The idea that a rocket sitting on top of a column of thrust is significantly different than a rocket suspended underneath a column of thrust is actually a commo

The idea that a rocket sitting on top of a column of thrust is significantly different than a rocket suspended underneath a column of thrust is actually a common fallacy, known as the pendulum rocket fallacy: https://en.wikipedia.org/wiki/Pendulum_rocket_fallacy https://en.wikipedia.org/wiki/Pendulum_rocket_fallacy You are correct that longitudinal stability is applicable and important for most aircraft, but that is due to angle of attack and lift forces. Neither of which apply in a vacuum.