The Lockheed F-117 Nighthawk is a stealth ground-attack aircraft that used twin jet engines. It’s important to note that the F-117 Nighthawk may have used different engine variants throughout its production, and specific details, such as the heating value of the fuel and the mass flow rate, would need to be obtained from engine performance data or technical specifications. The efficiency of a specific engine 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,
- 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).