In aircraft design, the efficiency of an engine is often referred to as the thermal efficiency or overall efficiency of the propulsion system. It represents the ratio of useful work or power output of the engine to the total energy input from fuel. The efficiency is expressed as a percentage.
The formula for the efficiency (η) of an engine is defined as:
- η (eta) is the efficiency of the engine, expressed as a percentage.
- Useful Work or Power Output represents the mechanical work or power produced by the engine, typically measured in watts (W) or horsepower (HP).
- Total Energy Input is the total energy obtained from the fuel, often measured in joules (J) or British thermal units (BTU).