What is the term for the actual power delivered to the propeller of an aircraft engine?

The term for the actual power delivered to the propeller of an aircraft engine is referred to as brake horsepower. This is an important concept in the context of aircraft engines because it represents the net power available after losses due to friction and other inefficiencies within the engine. Brake horsepower is measured at the engine's output shaft and accounts for the actual performance capability of the engine.

By contrast, torque is a measure of rotational force and does not directly relate to the power output delivered to the propeller. Horsepower is a broader term that can refer to different calculations, but it does not specify the actual power at the output as brake horsepower does. Rated horsepower generally refers to the maximum power that an engine is designed to produce under specified conditions, which may not represent the actual power delivered during operation.

Understanding brake horsepower helps in evaluating engine performance and efficiency, particularly in aviation, where it is critical to know how much power the engine can effectively deliver to lift and propel the aircraft.