Abstract
In this study, firstly we endeavor to prescribe logic definitions and reasoning process for obtaining correct rocket power and relevant efficiency equations. With the Lagrangian Reynolds transport approach, we also rigorously derive these highly generalized equations for rocket total kinetic power, thrust power and related propulsive, thermal, and overall efficiencies. They involve a few more physical effects including rocket acceleration, relative flow velocity / steadiness, outlet pressure, and gravity, thus open an original route for improving rocket propulsion analysis / design. Incidentally, it is interesting to note that under some conditions, a rocket in flight may retain less kinetic energy due to ejecting more kinetic energy of burning propellant per second than the thrust power acquired. Also, the derived correct rocket total kinetic power equations are quite reasonable in that all the velocities involved are of relative nature, thus invariant with respect to different observers and shielding the possibility of violating energy conservation law.
