How is engine output commonly measured in aviation?

In aviation, engine output is often measured in brake horsepower (BHP). This measurement refers to the engine's output power before losses like friction and heat within the engine are accounted for. It specifically indicates the amount of power that the engine produces and is typically used for piston engines.

Brake horsepower is significant because it's a standardized way to quantify the power output of engines, allowing comparisons between different engine designs and facilitate performance calculations for aircraft. The measurement focuses on the usable energy produced by the engine to generate thrust, providing a clear understanding of the engine's performance capabilities in operational conditions.

While torque, shaft horsepower (SHP), and thrust are also important metrics in assessing engine performance, they serve different purposes or apply under different contexts. Torque measures the rotational force produced by the engine, which can be significant in certain operational conditions but does not directly translate to engine output in the same way BHP does. SHP is another measure that refers to the power available at the engine's output shaft, which, while relevant, is frequently represented in a context that also includes comprehensive performance data. Thrust is specific to jet engines, indicating the force produced to propel the aircraft forward, but it does not broadly encompass all types of aircraft engines, such as reciprocating engines