The rocket analogue of a flywheel is a very heavy rocket, whose large inertia would smooth the changes in its velocity due to propulsion pulses. Nevertheless,

The rocket analogue of a flywheel is a very heavy rocket, whose large inertia would smooth the changes in its velocity due to propulsion pulses. Nevertheless, this solution is undesirable, because it would limit the acceleration of the rocket to small values. The right solution is that mentioned by the other poster, i.e. to have a large number of pulsed rocket engines, whose pulses should have distinct phases. In this case there should be pairs of engines with synchronized pulses and symmetric positions, to avoid the rotation of the rocket, because the engines can no longer be aligned with its center of inertia.