The propulsive efficiency of a hypergolic bipropellant rocket engine can be calculated similarly to the general case mentioned earlier. Hypergolic propellants are those that ignite spontaneously upon contact with each other, eliminating the need for an external ignition source. A bipropellant system uses two separate components, typically a fuel and an oxidizer, which are mixed and ignited in the combustion chamber.
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).