FAA Powerplant Written Practice Test

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

1. Indicated HP

2. Net HP

3. Brake HP

4. Friction HP

The correct answer is: Brake HP

The term that describes the actual power delivered to the propeller of an aircraft engine is known as "brake horsepower." Brake horsepower is a measure of the engine’s power output, which is determined after the engine has been tested at the flywheel and takes into account the losses due to mechanical resistance and friction within the engine. It represents the usable power that can actually perform work, in this case, turning the propeller. Indicated horsepower refers to the power calculated based on pressure measurements in the cylinders without accounting for losses, while net horsepower typically considers the power available for work after certain losses have been subtracted, but it is not the standard term used for propeller-driven power. Friction horsepower specifically refers to the power lost due to internal friction within the engine components and does not contribute to the useful output at the propeller. Therefore, brake horsepower is the most accurate measure of the actual power delivered to the propeller, as it directly correlates to the performance and efficiency of the aircraft engine.