Suborbital rockets are designed to reach altitudes above the Earth’s atmosphere but not to achieve orbital velocity. They are typically used for scientific research, testing, or commercial purposes such as space tourism. The efficiency of a specific suborbital rocket can be influenced by design parameters, operating conditions, and other factors.
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,
- ṁp 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).