Ramps

I would disagree with most of these arguments. First work out the Force which is rate of change of momentum (remember that the momentum is comprised the instantaneous velocity multiplied by the rate of change of mass plus the mass multiplied by the rate of change of velocity). Integrate over a suitably small time frame and multiply by the distance travelled. This will be the work done or energy to move the rocket a distance x. The actual energy supplied by burning the fuel is the mass of fuel used multiplied by the specific exothermic energy per unit mass in breaking and creating bonds in the chemical reaction. The efficiency is then 100x difference in Energy supplied by fuel - work done divided by energy supplied by burning said fuel