The Saturn V rocket, used during the Apollo program, was a multi-stage liquid-fueled launch vehicle. It used a variety of rocket engines for propulsion, including the F-1 engines on the first stage. These engines burned a combination of liquid oxygen (LOX) and kerosene (RP-1) to generate thrust.
The propulsive efficiency () of a rocket engine, including the engines used in the Saturn V rocket, is typically expressed in terms of the specific impulse (). Specific impulse is a measure of the efficiency of a rocket engine and is defined as the thrust per unit mass flow rate of propellant.
The propulsive efficiency is a crucial parameter in evaluating the performance of a rocket engine, indicating how well it converts propellant energy into useful thrust. Practical rocket engines often have propulsive efficiencies less than 100% due to factors like incomplete combustion, heat losses, and other inefficiencies in the propulsion system.
The propulsive efficiency () is defined by the following formula:
where,
- is the propulsive efficiency,
- is the thrust produced by the rocket engine,
- is the effective exhaust velocity of the rocket,
- ṁ is the mass flow rate of the propellants,
- is the specific impulse of the rocket engine,
- g0 is the acceleration due to gravity (approximately 9.81 m/s²).