FAA Powerplant Written Practice Test

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Prepare for the FAA Powerplant Written Test. Study with flashcards and multiple choice questions, each featuring hints and explanations. Ace your exam with confidence!

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What does the equation PLANK/33,000 define?

Indicated HP
Thermal efficiency of an engine
Propulsive efficiency
Mechanical efficiency

The correct answer is: Indicated HP

The equation PLANK/33,000 defines indicated horsepower (HP). Indicated horsepower refers to the theoretical power output of the engine based on the pressure applied to the pistons within the engine cylinders. The term "PLANK" in the equation encompasses various factors such as the mean effective pressure, the area of the piston, the stroke length, and the engine speed. The constant 33,000 is used to convert foot-pounds per minute into horsepower, acknowledging that one horsepower is defined as the ability to do 33,000 foot-pounds of work per minute. Indicated horsepower is an important measure because it indicates the power generated by the combustion process in the engine, without accounting for the losses due to factors like friction and heat transfer that occur in the actual operation of the engine. Understanding indicated horsepower is vital for engineers and mechanics as it allows for the evaluation of engine performance and its efficiency under ideal conditions.